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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 8.11 10-Oct-2010
5    ------------------------
6    
7    1.  (*THEN) was not working properly if there were untried alternatives prior
8        to it in the current branch. For example, in ((a|b)(*THEN)(*F)|c..) it
9        backtracked to try for "b" instead of moving to the next alternative branch
10        at the same level (in this case, to look for "c"). The Perl documentation
11        is clear that when (*THEN) is backtracked onto, it goes to the "next
12        alternative in the innermost enclosing group".
13    
14    2.  (*COMMIT) was not overriding (*THEN), as it does in Perl. In a pattern
15        such as   (A(*COMMIT)B(*THEN)C|D)  any failure after matching A should
16        result in overall failure. Similarly, (*COMMIT) now overrides (*PRUNE) and
17        (*SKIP), (*SKIP) overrides (*PRUNE) and (*THEN), and (*PRUNE) overrides
18        (*THEN).
19    
20    3.  If \s appeared in a character class, it removed the VT character from
21        the class, even if it had been included by some previous item, for example
22        in [\x00-\xff\s]. (This was a bug related to the fact that VT is not part
23        of \s, but is part of the POSIX "space" class.)
24    
25    4.  A partial match never returns an empty string (because you can always
26        match an empty string at the end of the subject); however the checking for
27        an empty string was starting at the "start of match" point. This has been
28        changed to the "earliest inspected character" point, because the returned
29        data for a partial match starts at this character. This means that, for
30        example, /(?<=abc)def/ gives a partial match for the subject "abc"
31        (previously it gave "no match").
32    
33    5.  Changes have been made to the way PCRE_PARTIAL_HARD affects the matching
34        of $, \z, \Z, \b, and \B. If the match point is at the end of the string,
35        previously a full match would be given. However, setting PCRE_PARTIAL_HARD
36        has an implication that the given string is incomplete (because a partial
37        match is preferred over a full match). For this reason, these items now
38        give a partial match in this situation. [Aside: previously, the one case
39        /t\b/ matched against "cat" with PCRE_PARTIAL_HARD set did return a partial
40        match rather than a full match, which was wrong by the old rules, but is
41        now correct.]
42    
43    6.  There was a bug in the handling of #-introduced comments, recognized when
44        PCRE_EXTENDED is set, when PCRE_NEWLINE_ANY and PCRE_UTF8 were also set.
45        If a UTF-8 multi-byte character included the byte 0x85 (e.g. +U0445, whose
46        UTF-8 encoding is 0xd1,0x85), this was misinterpreted as a newline when
47        scanning for the end of the comment. (*Character* 0x85 is an "any" newline,
48        but *byte* 0x85 is not, in UTF-8 mode). This bug was present in several
49        places in pcre_compile().
50    
51    7.  Related to (6) above, when pcre_compile() was skipping #-introduced
52        comments when looking ahead for named forward references to subpatterns,
53        the only newline sequence it recognized was NL. It now handles newlines
54        according to the set newline convention.
55    
56    8.  SunOS4 doesn't have strerror() or strtoul(); pcregrep dealt with the
57        former, but used strtoul(), whereas pcretest avoided strtoul() but did not
58        cater for a lack of strerror(). These oversights have been fixed.
59    
60    9.  Added --match-limit and --recursion-limit to pcregrep.
61    
62    10. Added two casts needed to build with Visual Studio when NO_RECURSE is set.
63    
64    11. When the -o option was used, pcregrep was setting a return code of 1, even
65        when matches were found, and --line-buffered was not being honoured.
66    
67    12. Added an optional parentheses number to the -o and --only-matching options
68        of pcregrep.
69    
70    13. Imitating Perl's /g action for multiple matches is tricky when the pattern
71        can match an empty string. The code to do it in pcretest and pcredemo
72        needed fixing:
73    
74        (a) When the newline convention was "crlf", pcretest got it wrong, skipping
75            only one byte after an empty string match just before CRLF (this case
76            just got forgotten; "any" and "anycrlf" were OK).
77    
78        (b) The pcretest code also had a bug, causing it to loop forever in UTF-8
79            mode when an empty string match preceded an ASCII character followed by
80            a non-ASCII character. (The code for advancing by one character rather
81            than one byte was nonsense.)
82    
83        (c) The pcredemo.c sample program did not have any code at all to handle
84            the cases when CRLF is a valid newline sequence.
85    
86    14. Neither pcre_exec() nor pcre_dfa_exec() was checking that the value given
87        as a starting offset was within the subject string. There is now a new
88        error, PCRE_ERROR_BADOFFSET, which is returned if the starting offset is
89        negative or greater than the length of the string. In order to test this,
90        pcretest is extended to allow the setting of negative starting offsets.
91    
92    15. In both pcre_exec() and pcre_dfa_exec() the code for checking that the
93        starting offset points to the beginning of a UTF-8 character was
94        unnecessarily clumsy. I tidied it up.
95    
96    16. Added PCRE_ERROR_SHORTUTF8 to make it possible to distinguish between a
97        bad UTF-8 sequence and one that is incomplete.
98    
99    17. Nobody had reported that the --include_dir option, which was added in
100        release 7.7 should have been called --include-dir (hyphen, not underscore)
101        for compatibility with GNU grep. I have changed it to --include-dir, but
102        left --include_dir as an undocumented synonym, and the same for
103        --exclude-dir, though that is not available in GNU grep, at least as of
104        release 2.5.4.
105    
106    
107    Version 8.10 25-Jun-2010
108    ------------------------
109    
110    1.  Added support for (*MARK:ARG) and for ARG additions to PRUNE, SKIP, and
111        THEN.
112    
113    2.  (*ACCEPT) was not working when inside an atomic group.
114    
115    3.  Inside a character class, \B is treated as a literal by default, but
116        faulted if PCRE_EXTRA is set. This mimics Perl's behaviour (the -w option
117        causes the error). The code is unchanged, but I tidied the documentation.
118    
119    4.  Inside a character class, PCRE always treated \R and \X as literals,
120        whereas Perl faults them if its -w option is set. I have changed PCRE so
121        that it faults them when PCRE_EXTRA is set.
122    
123    5.  Added support for \N, which always matches any character other than
124        newline. (It is the same as "." when PCRE_DOTALL is not set.)
125    
126    6.  When compiling pcregrep with newer versions of gcc which may have
127        FORTIFY_SOURCE set, several warnings "ignoring return value of 'fwrite',
128        declared with attribute warn_unused_result" were given. Just casting the
129        result to (void) does not stop the warnings; a more elaborate fudge is
130        needed. I've used a macro to implement this.
131    
132    7.  Minor change to pcretest.c to avoid a compiler warning.
133    
134    8.  Added four artifical Unicode properties to help with an option to make
135        \s etc use properties (see next item). The new properties are: Xan
136        (alphanumeric), Xsp (Perl space), Xps (POSIX space), and Xwd (word).
137    
138    9.  Added PCRE_UCP to make \b, \d, \s, \w, and certain POSIX character classes
139        use Unicode properties. (*UCP) at the start of a pattern can be used to set
140        this option. Modified pcretest to add /W to test this facility. Added
141        REG_UCP to make it available via the POSIX interface.
142    
143    10. Added --line-buffered to pcregrep.
144    
145    11. In UTF-8 mode, if a pattern that was compiled with PCRE_CASELESS was
146        studied, and the match started with a letter with a code point greater than
147        127 whose first byte was different to the first byte of the other case of
148        the letter, the other case of this starting letter was not recognized
149        (#976).
150    
151    12. If a pattern that was studied started with a repeated Unicode property
152        test, for example, \p{Nd}+, there was the theoretical possibility of
153        setting up an incorrect bitmap of starting bytes, but fortunately it could
154        not have actually happened in practice until change 8 above was made (it
155        added property types that matched character-matching opcodes).
156    
157    13. pcre_study() now recognizes \h, \v, and \R when constructing a bit map of
158        possible starting bytes for non-anchored patterns.
159    
160    14. Extended the "auto-possessify" feature of pcre_compile(). It now recognizes
161        \R, and also a number of cases that involve Unicode properties, both
162        explicit and implicit when PCRE_UCP is set.
163    
164    15. If a repeated Unicode property match (e.g. \p{Lu}*) was used with non-UTF-8
165        input, it could crash or give wrong results if characters with values
166        greater than 0xc0 were present in the subject string. (Detail: it assumed
167        UTF-8 input when processing these items.)
168    
169    16. Added a lot of (int) casts to avoid compiler warnings in systems where
170        size_t is 64-bit (#991).
171    
172    17. Added a check for running out of memory when PCRE is compiled with
173        --disable-stack-for-recursion (#990).
174    
175    18. If the last data line in a file for pcretest does not have a newline on
176        the end, a newline was missing in the output.
177    
178    19. The default pcre_chartables.c file recognizes only ASCII characters (values
179        less than 128) in its various bitmaps. However, there is a facility for
180        generating tables according to the current locale when PCRE is compiled. It
181        turns out that in some environments, 0x85 and 0xa0, which are Unicode space
182        characters, are recognized by isspace() and therefore were getting set in
183        these tables, and indeed these tables seem to approximate to ISO 8859. This
184        caused a problem in UTF-8 mode when pcre_study() was used to create a list
185        of bytes that can start a match. For \s, it was including 0x85 and 0xa0,
186        which of course cannot start UTF-8 characters. I have changed the code so
187        that only real ASCII characters (less than 128) and the correct starting
188        bytes for UTF-8 encodings are set for characters greater than 127 when in
189        UTF-8 mode. (When PCRE_UCP is set - see 9 above - the code is different
190        altogether.)
191    
192    20. Added the /T option to pcretest so as to be able to run tests with non-
193        standard character tables, thus making it possible to include the tests
194        used for 19 above in the standard set of tests.
195    
196    21. A pattern such as (?&t)(?#()(?(DEFINE)(?<t>a)) which has a forward
197        reference to a subpattern the other side of a comment that contains an
198        opening parenthesis caused either an internal compiling error, or a
199        reference to the wrong subpattern.
200    
201    
202    Version 8.02 19-Mar-2010
203    ------------------------
204    
205    1.  The Unicode data tables have been updated to Unicode 5.2.0.
206    
207    2.  Added the option --libs-cpp to pcre-config, but only when C++ support is
208        configured.
209    
210    3.  Updated the licensing terms in the pcregexp.pas file, as agreed with the
211        original author of that file, following a query about its status.
212    
213    4.  On systems that do not have stdint.h (e.g. Solaris), check for and include
214        inttypes.h instead. This fixes a bug that was introduced by change 8.01/8.
215    
216    5.  A pattern such as (?&t)*+(?(DEFINE)(?<t>.)) which has a possessive
217        quantifier applied to a forward-referencing subroutine call, could compile
218        incorrect code or give the error "internal error: previously-checked
219        referenced subpattern not found".
220    
221    6.  Both MS Visual Studio and Symbian OS have problems with initializing
222        variables to point to external functions. For these systems, therefore,
223        pcre_malloc etc. are now initialized to local functions that call the
224        relevant global functions.
225    
226    7.  There were two entries missing in the vectors called coptable and poptable
227        in pcre_dfa_exec.c. This could lead to memory accesses outsize the vectors.
228        I've fixed the data, and added a kludgy way of testing at compile time that
229        the lengths are correct (equal to the number of opcodes).
230    
231    8.  Following on from 7, I added a similar kludge to check the length of the
232        eint vector in pcreposix.c.
233    
234    9.  Error texts for pcre_compile() are held as one long string to avoid too
235        much relocation at load time. To find a text, the string is searched,
236        counting zeros. There was no check for running off the end of the string,
237        which could happen if a new error number was added without updating the
238        string.
239    
240    10. \K gave a compile-time error if it appeared in a lookbehind assersion.
241    
242    11. \K was not working if it appeared in an atomic group or in a group that
243        was called as a "subroutine", or in an assertion. Perl 5.11 documents that
244        \K is "not well defined" if used in an assertion. PCRE now accepts it if
245        the assertion is positive, but not if it is negative.
246    
247    12. Change 11 fortuitously reduced the size of the stack frame used in the
248        "match()" function of pcre_exec.c by one pointer. Forthcoming
249        implementation of support for (*MARK) will need an extra pointer on the
250        stack; I have reserved it now, so that the stack frame size does not
251        decrease.
252    
253    13. A pattern such as (?P<L1>(?P<L2>0)|(?P>L2)(?P>L1)) in which the only other
254        item in branch that calls a recursion is a subroutine call - as in the
255        second branch in the above example - was incorrectly given the compile-
256        time error "recursive call could loop indefinitely" because pcre_compile()
257        was not correctly checking the subroutine for matching a non-empty string.
258    
259    14. The checks for overrunning compiling workspace could trigger after an
260        overrun had occurred. This is a "should never occur" error, but it can be
261        triggered by pathological patterns such as hundreds of nested parentheses.
262        The checks now trigger 100 bytes before the end of the workspace.
263    
264    15. Fix typo in configure.ac: "srtoq" should be "strtoq".
265    
266    
267    Version 8.01 19-Jan-2010
268    ------------------------
269    
270    1.  If a pattern contained a conditional subpattern with only one branch (in
271        particular, this includes all (*DEFINE) patterns), a call to pcre_study()
272        computed the wrong minimum data length (which is of course zero for such
273        subpatterns). This could cause incorrect "no match" results.
274    
275    2.  For patterns such as (?i)a(?-i)b|c where an option setting at the start of
276        the pattern is reset in the first branch, pcre_compile() failed with
277        "internal error: code overflow at offset...". This happened only when
278        the reset was to the original external option setting. (An optimization
279        abstracts leading options settings into an external setting, which was the
280        cause of this.)
281    
282    3.  A pattern such as ^(?!a(*SKIP)b) where a negative assertion contained one
283        of the verbs SKIP, PRUNE, or COMMIT, did not work correctly. When the
284        assertion pattern did not match (meaning that the assertion was true), it
285        was incorrectly treated as false if the SKIP had been reached during the
286        matching. This also applied to assertions used as conditions.
287    
288    4.  If an item that is not supported by pcre_dfa_exec() was encountered in an
289        assertion subpattern, including such a pattern used as a condition,
290        unpredictable results occurred, instead of the error return
291        PCRE_ERROR_DFA_UITEM.
292    
293    5.  The C++ GlobalReplace function was not working like Perl for the special
294        situation when an empty string is matched. It now does the fancy magic
295        stuff that is necessary.
296    
297    6.  In pcre_internal.h, obsolete includes to setjmp.h and stdarg.h have been
298        removed. (These were left over from very, very early versions of PCRE.)
299    
300    7.  Some cosmetic changes to the code to make life easier when compiling it
301        as part of something else:
302    
303        (a) Change DEBUG to PCRE_DEBUG.
304    
305        (b) In pcre_compile(), rename the member of the "branch_chain" structure
306            called "current" as "current_branch", to prevent a collision with the
307            Linux macro when compiled as a kernel module.
308    
309        (c) In pcre_study(), rename the function set_bit() as set_table_bit(), to
310            prevent a collision with the Linux macro when compiled as a kernel
311            module.
312    
313    8.  In pcre_compile() there are some checks for integer overflows that used to
314        cast potentially large values to (double). This has been changed to that
315        when building, a check for int64_t is made, and if it is found, it is used
316        instead, thus avoiding the use of floating point arithmetic. (There is no
317        other use of FP in PCRE.) If int64_t is not found, the fallback is to
318        double.
319    
320    9.  Added two casts to avoid signed/unsigned warnings from VS Studio Express
321        2005 (difference between two addresses compared to an unsigned value).
322    
323    10. Change the standard AC_CHECK_LIB test for libbz2 in configure.ac to a
324        custom one, because of the following reported problem in Windows:
325    
326          - libbz2 uses the Pascal calling convention (WINAPI) for the functions
327              under Win32.
328          - The standard autoconf AC_CHECK_LIB fails to include "bzlib.h",
329              therefore missing the function definition.
330          - The compiler thus generates a "C" signature for the test function.
331          - The linker fails to find the "C" function.
332          - PCRE fails to configure if asked to do so against libbz2.
333    
334    11. When running libtoolize from libtool-2.2.6b as part of autogen.sh, these
335        messages were output:
336    
337          Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
338          rerunning libtoolize, to keep the correct libtool macros in-tree.
339          Consider adding `-I m4' to ACLOCAL_AMFLAGS in Makefile.am.
340    
341        I have done both of these things.
342    
343    12. Although pcre_dfa_exec() does not use nearly as much stack as pcre_exec()
344        most of the time, it *can* run out if it is given a pattern that contains a
345        runaway infinite recursion. I updated the discussion in the pcrestack man
346        page.
347    
348    13. Now that we have gone to the x.xx style of version numbers, the minor
349        version may start with zero. Using 08 or 09 is a bad idea because users
350        might check the value of PCRE_MINOR in their code, and 08 or 09 may be
351        interpreted as invalid octal numbers. I've updated the previous comment in
352        configure.ac, and also added a check that gives an error if 08 or 09 are
353        used.
354    
355    14. Change 8.00/11 was not quite complete: code had been accidentally omitted,
356        causing partial matching to fail when the end of the subject matched \W
357        in a UTF-8 pattern where \W was quantified with a minimum of 3.
358    
359    15. There were some discrepancies between the declarations in pcre_internal.h
360        of _pcre_is_newline(), _pcre_was_newline(), and _pcre_valid_utf8() and
361        their definitions. The declarations used "const uschar *" and the
362        definitions used USPTR. Even though USPTR is normally defined as "const
363        unsigned char *" (and uschar is typedeffed as "unsigned char"), it was
364        reported that: "This difference in casting confuses some C++ compilers, for
365        example, SunCC recognizes above declarations as different functions and
366        generates broken code for hbpcre." I have changed the declarations to use
367        USPTR.
368    
369    16. GNU libtool is named differently on some systems. The autogen.sh script now
370        tries several variants such as glibtoolize (MacOSX) and libtoolize1x
371        (FreeBSD).
372    
373    17. Applied Craig's patch that fixes an HP aCC compile error in pcre 8.00
374        (strtoXX undefined when compiling pcrecpp.cc). The patch contains this
375        comment: "Figure out how to create a longlong from a string: strtoll and
376        equivalent. It's not enough to call AC_CHECK_FUNCS: hpux has a strtoll, for
377        instance, but it only takes 2 args instead of 3!"
378    
379    18. A subtle bug concerned with back references has been fixed by a change of
380        specification, with a corresponding code fix. A pattern such as
381        ^(xa|=?\1a)+$ which contains a back reference inside the group to which it
382        refers, was giving matches when it shouldn't. For example, xa=xaaa would
383        match that pattern. Interestingly, Perl (at least up to 5.11.3) has the
384        same bug. Such groups have to be quantified to be useful, or contained
385        inside another quantified group. (If there's no repetition, the reference
386        can never match.) The problem arises because, having left the group and
387        moved on to the rest of the pattern, a later failure that backtracks into
388        the group uses the captured value from the final iteration of the group
389        rather than the correct earlier one. I have fixed this in PCRE by forcing
390        any group that contains a reference to itself to be an atomic group; that
391        is, there cannot be any backtracking into it once it has completed. This is
392        similar to recursive and subroutine calls.
393    
394    
395    Version 8.00 19-Oct-09
396    ----------------------
397    
398    1.  The table for translating pcre_compile() error codes into POSIX error codes
399        was out-of-date, and there was no check on the pcre_compile() error code
400        being within the table. This could lead to an OK return being given in
401        error.
402    
403    2.  Changed the call to open a subject file in pcregrep from fopen(pathname,
404        "r") to fopen(pathname, "rb"), which fixed a problem with some of the tests
405        in a Windows environment.
406    
407    3.  The pcregrep --count option prints the count for each file even when it is
408        zero, as does GNU grep. However, pcregrep was also printing all files when
409        --files-with-matches was added. Now, when both options are given, it prints
410        counts only for those files that have at least one match. (GNU grep just
411        prints the file name in this circumstance, but including the count seems
412        more useful - otherwise, why use --count?) Also ensured that the
413        combination -clh just lists non-zero counts, with no names.
414    
415    4.  The long form of the pcregrep -F option was incorrectly implemented as
416        --fixed_strings instead of --fixed-strings. This is an incompatible change,
417        but it seems right to fix it, and I didn't think it was worth preserving
418        the old behaviour.
419    
420    5.  The command line items --regex=pattern and --regexp=pattern were not
421        recognized by pcregrep, which required --regex pattern or --regexp pattern
422        (with a space rather than an '='). The man page documented the '=' forms,
423        which are compatible with GNU grep; these now work.
424    
425    6.  No libpcreposix.pc file was created for pkg-config; there was just
426        libpcre.pc and libpcrecpp.pc. The omission has been rectified.
427    
428    7.  Added #ifndef SUPPORT_UCP into the pcre_ucd.c module, to reduce its size
429        when UCP support is not needed, by modifying the Python script that
430        generates it from Unicode data files. This should not matter if the module
431        is correctly used as a library, but I received one complaint about 50K of
432        unwanted data. My guess is that the person linked everything into his
433        program rather than using a library. Anyway, it does no harm.
434    
435    8.  A pattern such as /\x{123}{2,2}+/8 was incorrectly compiled; the trigger
436        was a minimum greater than 1 for a wide character in a possessive
437        repetition. The same bug could also affect patterns like /(\x{ff}{0,2})*/8
438        which had an unlimited repeat of a nested, fixed maximum repeat of a wide
439        character. Chaos in the form of incorrect output or a compiling loop could
440        result.
441    
442    9.  The restrictions on what a pattern can contain when partial matching is
443        requested for pcre_exec() have been removed. All patterns can now be
444        partially matched by this function. In addition, if there are at least two
445        slots in the offset vector, the offset of the earliest inspected character
446        for the match and the offset of the end of the subject are set in them when
447        PCRE_ERROR_PARTIAL is returned.
448    
449    10. Partial matching has been split into two forms: PCRE_PARTIAL_SOFT, which is
450        synonymous with PCRE_PARTIAL, for backwards compatibility, and
451        PCRE_PARTIAL_HARD, which causes a partial match to supersede a full match,
452        and may be more useful for multi-segment matching.
453    
454    11. Partial matching with pcre_exec() is now more intuitive. A partial match
455        used to be given if ever the end of the subject was reached; now it is
456        given only if matching could not proceed because another character was
457        needed. This makes a difference in some odd cases such as Z(*FAIL) with the
458        string "Z", which now yields "no match" instead of "partial match". In the
459        case of pcre_dfa_exec(), "no match" is given if every matching path for the
460        final character ended with (*FAIL).
461    
462    12. Restarting a match using pcre_dfa_exec() after a partial match did not work
463        if the pattern had a "must contain" character that was already found in the
464        earlier partial match, unless partial matching was again requested. For
465        example, with the pattern /dog.(body)?/, the "must contain" character is
466        "g". If the first part-match was for the string "dog", restarting with
467        "sbody" failed. This bug has been fixed.
468    
469    13. The string returned by pcre_dfa_exec() after a partial match has been
470        changed so that it starts at the first inspected character rather than the
471        first character of the match. This makes a difference only if the pattern
472        starts with a lookbehind assertion or \b or \B (\K is not supported by
473        pcre_dfa_exec()). It's an incompatible change, but it makes the two
474        matching functions compatible, and I think it's the right thing to do.
475    
476    14. Added a pcredemo man page, created automatically from the pcredemo.c file,
477        so that the demonstration program is easily available in environments where
478        PCRE has not been installed from source.
479    
480    15. Arranged to add -DPCRE_STATIC to cflags in libpcre.pc, libpcreposix.cp,
481        libpcrecpp.pc and pcre-config when PCRE is not compiled as a shared
482        library.
483    
484    16. Added REG_UNGREEDY to the pcreposix interface, at the request of a user.
485        It maps to PCRE_UNGREEDY. It is not, of course, POSIX-compatible, but it
486        is not the first non-POSIX option to be added. Clearly some people find
487        these options useful.
488    
489    17. If a caller to the POSIX matching function regexec() passes a non-zero
490        value for nmatch with a NULL value for pmatch, the value of
491        nmatch is forced to zero.
492    
493    18. RunGrepTest did not have a test for the availability of the -u option of
494        the diff command, as RunTest does. It now checks in the same way as
495        RunTest, and also checks for the -b option.
496    
497    19. If an odd number of negated classes containing just a single character
498        interposed, within parentheses, between a forward reference to a named
499        subpattern and the definition of the subpattern, compilation crashed with
500        an internal error, complaining that it could not find the referenced
501        subpattern. An example of a crashing pattern is /(?&A)(([^m])(?<A>))/.
502        [The bug was that it was starting one character too far in when skipping
503        over the character class, thus treating the ] as data rather than
504        terminating the class. This meant it could skip too much.]
505    
506    20. Added PCRE_NOTEMPTY_ATSTART in order to be able to correctly implement the
507        /g option in pcretest when the pattern contains \K, which makes it possible
508        to have an empty string match not at the start, even when the pattern is
509        anchored. Updated pcretest and pcredemo to use this option.
510    
511    21. If the maximum number of capturing subpatterns in a recursion was greater
512        than the maximum at the outer level, the higher number was returned, but
513        with unset values at the outer level. The correct (outer level) value is
514        now given.
515    
516    22. If (*ACCEPT) appeared inside capturing parentheses, previous releases of
517        PCRE did not set those parentheses (unlike Perl). I have now found a way to
518        make it do so. The string so far is captured, making this feature
519        compatible with Perl.
520    
521    23. The tests have been re-organized, adding tests 11 and 12, to make it
522        possible to check the Perl 5.10 features against Perl 5.10.
523    
524    24. Perl 5.10 allows subroutine calls in lookbehinds, as long as the subroutine
525        pattern matches a fixed length string. PCRE did not allow this; now it
526        does. Neither allows recursion.
527    
528    25. I finally figured out how to implement a request to provide the minimum
529        length of subject string that was needed in order to match a given pattern.
530        (It was back references and recursion that I had previously got hung up
531        on.) This code has now been added to pcre_study(); it finds a lower bound
532        to the length of subject needed. It is not necessarily the greatest lower
533        bound, but using it to avoid searching strings that are too short does give
534        some useful speed-ups. The value is available to calling programs via
535        pcre_fullinfo().
536    
537    26. While implementing 25, I discovered to my embarrassment that pcretest had
538        not been passing the result of pcre_study() to pcre_dfa_exec(), so the
539        study optimizations had never been tested with that matching function.
540        Oops. What is worse, even when it was passed study data, there was a bug in
541        pcre_dfa_exec() that meant it never actually used it. Double oops. There
542        were also very few tests of studied patterns with pcre_dfa_exec().
543    
544    27. If (?| is used to create subpatterns with duplicate numbers, they are now
545        allowed to have the same name, even if PCRE_DUPNAMES is not set. However,
546        on the other side of the coin, they are no longer allowed to have different
547        names, because these cannot be distinguished in PCRE, and this has caused
548        confusion. (This is a difference from Perl.)
549    
550    28. When duplicate subpattern names are present (necessarily with different
551        numbers, as required by 27 above), and a test is made by name in a
552        conditional pattern, either for a subpattern having been matched, or for
553        recursion in such a pattern, all the associated numbered subpatterns are
554        tested, and the overall condition is true if the condition is true for any
555        one of them. This is the way Perl works, and is also more like the way
556        testing by number works.
557    
558    
559    Version 7.9 11-Apr-09
560    ---------------------
561    
562    1.  When building with support for bzlib/zlib (pcregrep) and/or readline
563        (pcretest), all targets were linked against these libraries. This included
564        libpcre, libpcreposix, and libpcrecpp, even though they do not use these
565        libraries. This caused unwanted dependencies to be created. This problem
566        has been fixed, and now only pcregrep is linked with bzlib/zlib and only
567        pcretest is linked with readline.
568    
569    2.  The "typedef int BOOL" in pcre_internal.h that was included inside the
570        "#ifndef FALSE" condition by an earlier change (probably 7.8/18) has been
571        moved outside it again, because FALSE and TRUE are already defined in AIX,
572        but BOOL is not.
573    
574    3.  The pcre_config() function was treating the PCRE_MATCH_LIMIT and
575        PCRE_MATCH_LIMIT_RECURSION values as ints, when they should be long ints.
576    
577    4.  The pcregrep documentation said spaces were inserted as well as colons (or
578        hyphens) following file names and line numbers when outputting matching
579        lines. This is not true; no spaces are inserted. I have also clarified the
580        wording for the --colour (or --color) option.
581    
582    5.  In pcregrep, when --colour was used with -o, the list of matching strings
583        was not coloured; this is different to GNU grep, so I have changed it to be
584        the same.
585    
586    6.  When --colo(u)r was used in pcregrep, only the first matching substring in
587        each matching line was coloured. Now it goes on to look for further matches
588        of any of the test patterns, which is the same behaviour as GNU grep.
589    
590    7.  A pattern that could match an empty string could cause pcregrep to loop; it
591        doesn't make sense to accept an empty string match in pcregrep, so I have
592        locked it out (using PCRE's PCRE_NOTEMPTY option). By experiment, this
593        seems to be how GNU grep behaves.
594    
595    8.  The pattern (?(?=.*b)b|^) was incorrectly compiled as "match must be at
596        start or after a newline", because the conditional assertion was not being
597        correctly handled. The rule now is that both the assertion and what follows
598        in the first alternative must satisfy the test.
599    
600    9.  If auto-callout was enabled in a pattern with a conditional group whose
601        condition was an assertion, PCRE could crash during matching, both with
602        pcre_exec() and pcre_dfa_exec().
603    
604    10. The PCRE_DOLLAR_ENDONLY option was not working when pcre_dfa_exec() was
605        used for matching.
606    
607    11. Unicode property support in character classes was not working for
608        characters (bytes) greater than 127 when not in UTF-8 mode.
609    
610    12. Added the -M command line option to pcretest.
611    
612    14. Added the non-standard REG_NOTEMPTY option to the POSIX interface.
613    
614    15. Added the PCRE_NO_START_OPTIMIZE match-time option.
615    
616    16. Added comments and documentation about mis-use of no_arg in the C++
617        wrapper.
618    
619    17. Implemented support for UTF-8 encoding in EBCDIC environments, a patch
620        from Martin Jerabek that uses macro names for all relevant character and
621        string constants.
622    
623    18. Added to pcre_internal.h two configuration checks: (a) If both EBCDIC and
624        SUPPORT_UTF8 are set, give an error; (b) If SUPPORT_UCP is set without
625        SUPPORT_UTF8, define SUPPORT_UTF8. The "configure" script handles both of
626        these, but not everybody uses configure.
627    
628    19. A conditional group that had only one branch was not being correctly
629        recognized as an item that could match an empty string. This meant that an
630        enclosing group might also not be so recognized, causing infinite looping
631        (and probably a segfault) for patterns such as ^"((?(?=[a])[^"])|b)*"$
632        with the subject "ab", where knowledge that the repeated group can match
633        nothing is needed in order to break the loop.
634    
635    20. If a pattern that was compiled with callouts was matched using pcre_dfa_
636        exec(), but without supplying a callout function, matching went wrong.
637    
638    21. If PCRE_ERROR_MATCHLIMIT occurred during a recursion, there was a memory
639        leak if the size of the offset vector was greater than 30. When the vector
640        is smaller, the saved offsets during recursion go onto a local stack
641        vector, but for larger vectors malloc() is used. It was failing to free
642        when the recursion yielded PCRE_ERROR_MATCH_LIMIT (or any other "abnormal"
643        error, in fact).
644    
645    22. There was a missing #ifdef SUPPORT_UTF8 round one of the variables in the
646        heapframe that is used only when UTF-8 support is enabled. This caused no
647        problem, but was untidy.
648    
649    23. Steven Van Ingelgem's patch to CMakeLists.txt to change the name
650        CMAKE_BINARY_DIR to PROJECT_BINARY_DIR so that it works when PCRE is
651        included within another project.
652    
653    24. Steven Van Ingelgem's patches to add more options to the CMake support,
654        slightly modified by me:
655    
656          (a) PCRE_BUILD_TESTS can be set OFF not to build the tests, including
657              not building pcregrep.
658    
659          (b) PCRE_BUILD_PCREGREP can be see OFF not to build pcregrep, but only
660              if PCRE_BUILD_TESTS is also set OFF, because the tests use pcregrep.
661    
662    25. Forward references, both numeric and by name, in patterns that made use of
663        duplicate group numbers, could behave incorrectly or give incorrect errors,
664        because when scanning forward to find the reference group, PCRE was not
665        taking into account the duplicate group numbers. A pattern such as
666        ^X(?3)(a)(?|(b)|(q))(Y) is an example.
667    
668    26. Changed a few more instances of "const unsigned char *" to USPTR, making
669        the feature of a custom pointer more persuasive (as requested by a user).
670    
671    27. Wrapped the definitions of fileno and isatty for Windows, which appear in
672        pcretest.c, inside #ifndefs, because it seems they are sometimes already
673        pre-defined.
674    
675    28. Added support for (*UTF8) at the start of a pattern.
676    
677    29. Arrange for flags added by the "release type" setting in CMake to be shown
678        in the configuration summary.
679    
680    
681    Version 7.8 05-Sep-08
682    ---------------------
683    
684    1.  Replaced UCP searching code with optimized version as implemented for Ad
685        Muncher (http://www.admuncher.com/) by Peter Kankowski. This uses a two-
686        stage table and inline lookup instead of a function, giving speed ups of 2
687        to 5 times on some simple patterns that I tested. Permission was given to
688        distribute the MultiStage2.py script that generates the tables (it's not in
689        the tarball, but is in the Subversion repository).
690    
691    2.  Updated the Unicode datatables to Unicode 5.1.0. This adds yet more
692        scripts.
693    
694    3.  Change 12 for 7.7 introduced a bug in pcre_study() when a pattern contained
695        a group with a zero qualifier. The result of the study could be incorrect,
696        or the function might crash, depending on the pattern.
697    
698    4.  Caseless matching was not working for non-ASCII characters in back
699        references. For example, /(\x{de})\1/8i was not matching \x{de}\x{fe}.
700        It now works when Unicode Property Support is available.
701    
702    5.  In pcretest, an escape such as \x{de} in the data was always generating
703        a UTF-8 string, even in non-UTF-8 mode. Now it generates a single byte in
704        non-UTF-8 mode. If the value is greater than 255, it gives a warning about
705        truncation.
706    
707    6.  Minor bugfix in pcrecpp.cc (change "" == ... to NULL == ...).
708    
709    7.  Added two (int) casts to pcregrep when printing the difference of two
710        pointers, in case they are 64-bit values.
711    
712    8.  Added comments about Mac OS X stack usage to the pcrestack man page and to
713        test 2 if it fails.
714    
715    9.  Added PCRE_CALL_CONVENTION just before the names of all exported functions,
716        and a #define of that name to empty if it is not externally set. This is to
717        allow users of MSVC to set it if necessary.
718    
719    10. The PCRE_EXP_DEFN macro which precedes exported functions was missing from
720        the convenience functions in the pcre_get.c source file.
721    
722    11. An option change at the start of a pattern that had top-level alternatives
723        could cause overwriting and/or a crash. This command provoked a crash in
724        some environments:
725    
726          printf "/(?i)[\xc3\xa9\xc3\xbd]|[\xc3\xa9\xc3\xbdA]/8\n" | pcretest
727    
728        This potential security problem was recorded as CVE-2008-2371.
729    
730    12. For a pattern where the match had to start at the beginning or immediately
731        after a newline (e.g /.*anything/ without the DOTALL flag), pcre_exec() and
732        pcre_dfa_exec() could read past the end of the passed subject if there was
733        no match. To help with detecting such bugs (e.g. with valgrind), I modified
734        pcretest so that it places the subject at the end of its malloc-ed buffer.
735    
736    13. The change to pcretest in 12 above threw up a couple more cases when pcre_
737        exec() might read past the end of the data buffer in UTF-8 mode.
738    
739    14. A similar bug to 7.3/2 existed when the PCRE_FIRSTLINE option was set and
740        the data contained the byte 0x85 as part of a UTF-8 character within its
741        first line. This applied both to normal and DFA matching.
742    
743    15. Lazy qualifiers were not working in some cases in UTF-8 mode. For example,
744        /^[^d]*?$/8 failed to match "abc".
745    
746    16. Added a missing copyright notice to pcrecpp_internal.h.
747    
748    17. Make it more clear in the documentation that values returned from
749        pcre_exec() in ovector are byte offsets, not character counts.
750    
751    18. Tidied a few places to stop certain compilers from issuing warnings.
752    
753    19. Updated the Virtual Pascal + BCC files to compile the latest v7.7, as
754        supplied by Stefan Weber. I made a further small update for 7.8 because
755        there is a change of source arrangements: the pcre_searchfuncs.c module is
756        replaced by pcre_ucd.c.
757    
758    
759    Version 7.7 07-May-08
760    ---------------------
761    
762    1.  Applied Craig's patch to sort out a long long problem: "If we can't convert
763        a string to a long long, pretend we don't even have a long long." This is
764        done by checking for the strtoq, strtoll, and _strtoi64 functions.
765    
766    2.  Applied Craig's patch to pcrecpp.cc to restore ABI compatibility with
767        pre-7.6 versions, which defined a global no_arg variable instead of putting
768        it in the RE class. (See also #8 below.)
769    
770    3.  Remove a line of dead code, identified by coverity and reported by Nuno
771        Lopes.
772    
773    4.  Fixed two related pcregrep bugs involving -r with --include or --exclude:
774    
775        (1) The include/exclude patterns were being applied to the whole pathnames
776            of files, instead of just to the final components.
777    
778        (2) If there was more than one level of directory, the subdirectories were
779            skipped unless they satisfied the include/exclude conditions. This is
780            inconsistent with GNU grep (and could even be seen as contrary to the
781            pcregrep specification - which I improved to make it absolutely clear).
782            The action now is always to scan all levels of directory, and just
783            apply the include/exclude patterns to regular files.
784    
785    5.  Added the --include_dir and --exclude_dir patterns to pcregrep, and used
786        --exclude_dir in the tests to avoid scanning .svn directories.
787    
788    6.  Applied Craig's patch to the QuoteMeta function so that it escapes the
789        NUL character as backslash + 0 rather than backslash + NUL, because PCRE
790        doesn't support NULs in patterns.
791    
792    7.  Added some missing "const"s to declarations of static tables in
793        pcre_compile.c and pcre_dfa_exec.c.
794    
795    8.  Applied Craig's patch to pcrecpp.cc to fix a problem in OS X that was
796        caused by fix #2  above. (Subsequently also a second patch to fix the
797        first patch. And a third patch - this was a messy problem.)
798    
799    9.  Applied Craig's patch to remove the use of push_back().
800    
801    10. Applied Alan Lehotsky's patch to add REG_STARTEND support to the POSIX
802        matching function regexec().
803    
804    11. Added support for the Oniguruma syntax \g<name>, \g<n>, \g'name', \g'n',
805        which, however, unlike Perl's \g{...}, are subroutine calls, not back
806        references. PCRE supports relative numbers with this syntax (I don't think
807        Oniguruma does).
808    
809    12. Previously, a group with a zero repeat such as (...){0} was completely
810        omitted from the compiled regex. However, this means that if the group
811        was called as a subroutine from elsewhere in the pattern, things went wrong
812        (an internal error was given). Such groups are now left in the compiled
813        pattern, with a new opcode that causes them to be skipped at execution
814        time.
815    
816    13. Added the PCRE_JAVASCRIPT_COMPAT option. This makes the following changes
817        to the way PCRE behaves:
818    
819        (a) A lone ] character is dis-allowed (Perl treats it as data).
820    
821        (b) A back reference to an unmatched subpattern matches an empty string
822            (Perl fails the current match path).
823    
824        (c) A data ] in a character class must be notated as \] because if the
825            first data character in a class is ], it defines an empty class. (In
826            Perl it is not possible to have an empty class.) The empty class []
827            never matches; it forces failure and is equivalent to (*FAIL) or (?!).
828            The negative empty class [^] matches any one character, independently
829            of the DOTALL setting.
830    
831    14. A pattern such as /(?2)[]a()b](abc)/ which had a forward reference to a
832        non-existent subpattern following a character class starting with ']' and
833        containing () gave an internal compiling error instead of "reference to
834        non-existent subpattern". Fortunately, when the pattern did exist, the
835        compiled code was correct. (When scanning forwards to check for the
836        existencd of the subpattern, it was treating the data ']' as terminating
837        the class, so got the count wrong. When actually compiling, the reference
838        was subsequently set up correctly.)
839    
840    15. The "always fail" assertion (?!) is optimzed to (*FAIL) by pcre_compile;
841        it was being rejected as not supported by pcre_dfa_exec(), even though
842        other assertions are supported. I have made pcre_dfa_exec() support
843        (*FAIL).
844    
845    16. The implementation of 13c above involved the invention of a new opcode,
846        OP_ALLANY, which is like OP_ANY but doesn't check the /s flag. Since /s
847        cannot be changed at match time, I realized I could make a small
848        improvement to matching performance by compiling OP_ALLANY instead of
849        OP_ANY for "." when DOTALL was set, and then removing the runtime tests
850        on the OP_ANY path.
851    
852    17. Compiling pcretest on Windows with readline support failed without the
853        following two fixes: (1) Make the unistd.h include conditional on
854        HAVE_UNISTD_H; (2) #define isatty and fileno as _isatty and _fileno.
855    
856    18. Changed CMakeLists.txt and cmake/FindReadline.cmake to arrange for the
857        ncurses library to be included for pcretest when ReadLine support is
858        requested, but also to allow for it to be overridden. This patch came from
859        Daniel Bergström.
860    
861    19. There was a typo in the file ucpinternal.h where f0_rangeflag was defined
862        as 0x00f00000 instead of 0x00800000. Luckily, this would not have caused
863        any errors with the current Unicode tables. Thanks to Peter Kankowski for
864        spotting this.
865    
866    
867    Version 7.6 28-Jan-08
868    ---------------------
869    
870    1.  A character class containing a very large number of characters with
871        codepoints greater than 255 (in UTF-8 mode, of course) caused a buffer
872        overflow.
873    
874    2.  Patch to cut out the "long long" test in pcrecpp_unittest when
875        HAVE_LONG_LONG is not defined.
876    
877    3.  Applied Christian Ehrlicher's patch to update the CMake build files to
878        bring them up to date and include new features. This patch includes:
879    
880        - Fixed PH's badly added libz and libbz2 support.
881        - Fixed a problem with static linking.
882        - Added pcredemo. [But later removed - see 7 below.]
883        - Fixed dftables problem and added an option.
884        - Added a number of HAVE_XXX tests, including HAVE_WINDOWS_H and
885            HAVE_LONG_LONG.
886        - Added readline support for pcretest.
887        - Added an listing of the option settings after cmake has run.
888    
889    4.  A user submitted a patch to Makefile that makes it easy to create
890        "pcre.dll" under mingw when using Configure/Make. I added stuff to
891        Makefile.am that cause it to include this special target, without
892        affecting anything else. Note that the same mingw target plus all
893        the other distribution libraries and programs are now supported
894        when configuring with CMake (see 6 below) instead of with
895        Configure/Make.
896    
897    5.  Applied Craig's patch that moves no_arg into the RE class in the C++ code.
898        This is an attempt to solve the reported problem "pcrecpp::no_arg is not
899        exported in the Windows port". It has not yet been confirmed that the patch
900        solves the problem, but it does no harm.
901    
902    6.  Applied Sheri's patch to CMakeLists.txt to add NON_STANDARD_LIB_PREFIX and
903        NON_STANDARD_LIB_SUFFIX for dll names built with mingw when configured
904        with CMake, and also correct the comment about stack recursion.
905    
906    7.  Remove the automatic building of pcredemo from the ./configure system and
907        from CMakeLists.txt. The whole idea of pcredemo.c is that it is an example
908        of a program that users should build themselves after PCRE is installed, so
909        building it automatically is not really right. What is more, it gave
910        trouble in some build environments.
911    
912    8.  Further tidies to CMakeLists.txt from Sheri and Christian.
913    
914    
915    Version 7.5 10-Jan-08
916    ---------------------
917    
918    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
919        values in parens when parsing an RE using the C++ wrapper."
920    
921    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
922        Characters greater than 255 were excluded from the class instead of being
923        included.
924    
925    3.  The same bug as (2) above applied to negated POSIX classes such as
926        [:^space:].
927    
928    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
929        defined or documented. It seems to have been a typo for PCRE_STATIC, so
930        I have changed it.
931    
932    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
933        first named subpattern) and a construct such as (?&a) would reference the
934        first named subpattern whose name started with "a" (in other words, the
935        length check was missing). Both these problems are fixed. "Subpattern name
936        expected" is now given for (?&) (a zero-length name), and this patch also
937        makes it give the same error for \k'' (previously it complained that that
938        was a reference to a non-existent subpattern).
939    
940    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
941        this is right because (?- can be followed by option settings as well as by
942        digits. I have, however, made the messages clearer.
943    
944    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
945        than the number used in the conditional) now cause a compile-time error.
946        This is actually not compatible with Perl, which accepts such patterns, but
947        treats the conditional as always being FALSE (as PCRE used to), but it
948        seems to me that giving a diagnostic is better.
949    
950    8.  Change "alphameric" to the more common word "alphanumeric" in comments
951        and messages.
952    
953    9.  Fix two occurrences of "backslash" in comments that should have been
954        "backspace".
955    
956    10. Remove two redundant lines of code that can never be obeyed (their function
957        was moved elsewhere).
958    
959    11. The program that makes PCRE's Unicode character property table had a bug
960        which caused it to generate incorrect table entries for sequences of
961        characters that have the same character type, but are in different scripts.
962        It amalgamated them into a single range, with the script of the first of
963        them. In other words, some characters were in the wrong script. There were
964        thirteen such cases, affecting characters in the following ranges:
965    
966          U+002b0 - U+002c1
967          U+0060c - U+0060d
968          U+0061e - U+00612
969          U+0064b - U+0065e
970          U+0074d - U+0076d
971          U+01800 - U+01805
972          U+01d00 - U+01d77
973          U+01d9b - U+01dbf
974          U+0200b - U+0200f
975          U+030fc - U+030fe
976          U+03260 - U+0327f
977          U+0fb46 - U+0fbb1
978          U+10450 - U+1049d
979    
980    12. The -o option (show only the matching part of a line) for pcregrep was not
981        compatible with GNU grep in that, if there was more than one match in a
982        line, it showed only the first of them. It now behaves in the same way as
983        GNU grep.
984    
985    13. If the -o and -v options were combined for pcregrep, it printed a blank
986        line for every non-matching line. GNU grep prints nothing, and pcregrep now
987        does the same. The return code can be used to tell if there were any
988        non-matching lines.
989    
990    14. Added --file-offsets and --line-offsets to pcregrep.
991    
992    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
993        infinitely looping recursion. The bug was that positive lookaheads were not
994        being skipped when checking for a possible empty match (negative lookaheads
995        and both kinds of lookbehind were skipped).
996    
997    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
998        inclusion of <windows.h> to before rather than after the definition of
999        INVALID_FILE_ATTRIBUTES (patch from David Byron).
1000    
1001    17. Specifying a possessive quantifier with a specific limit for a Unicode
1002        character property caused pcre_compile() to compile bad code, which led at
1003        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
1004        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
1005        caused the error; without that there was no problem.
1006    
1007    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
1008    
1009    19. Added --enable-pcretest-libreadline.
1010    
1011    20. In pcrecpp.cc, the variable 'count' was incremented twice in
1012        RE::GlobalReplace(). As a result, the number of replacements returned was
1013        double what it should be. I removed one of the increments, but Craig sent a
1014        later patch that removed the other one (the right fix) and added unit tests
1015        that check the return values (which was not done before).
1016    
1017    21. Several CMake things:
1018    
1019        (1) Arranged that, when cmake is used on Unix, the libraries end up with
1020            the names libpcre and libpcreposix, not just pcre and pcreposix.
1021    
1022        (2) The above change means that pcretest and pcregrep are now correctly
1023            linked with the newly-built libraries, not previously installed ones.
1024    
1025        (3) Added PCRE_SUPPORT_LIBREADLINE, PCRE_SUPPORT_LIBZ, PCRE_SUPPORT_LIBBZ2.
1026    
1027    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
1028        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
1029        UTF-8 newline character). The key issue is that the pattern starts .*;
1030        this means that the match must be either at the beginning, or after a
1031        newline. The bug was in the code for advancing after a failed match and
1032        checking that the new position followed a newline. It was not taking
1033        account of UTF-8 characters correctly.
1034    
1035    23. PCRE was behaving differently from Perl in the way it recognized POSIX
1036        character classes. PCRE was not treating the sequence [:...:] as a
1037        character class unless the ... were all letters. Perl, however, seems to
1038        allow any characters between [: and :], though of course it rejects as
1039        unknown any "names" that contain non-letters, because all the known class
1040        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
1041        for example, whereas PCRE did not - it did not recognize a POSIX character
1042        class. This seemed a bit dangerous, so the code has been changed to be
1043        closer to Perl. The behaviour is not identical to Perl, because PCRE will
1044        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
1045        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
1046        Perl does, and where it didn't before.
1047    
1048    24. Rewrite so as to remove the single use of %n from pcregrep because in some
1049        Windows environments %n is disabled by default.
1050    
1051    
1052    Version 7.4 21-Sep-07
1053    ---------------------
1054    
1055    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
1056        means that a class such as [\s] counted as "explicit reference to CR or
1057        LF". That isn't really right - the whole point of the change was to try to
1058        help when there was an actual mention of one of the two characters. So now
1059        the change happens only if \r or \n (or a literal CR or LF) character is
1060        encountered.
1061    
1062    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
1063        of both had grown to the point where there were only 3 bits left.
1064        Fortunately, there was spare space in the data structure, and so I have
1065        moved the internal flags into a new 16-bit field to free up more option
1066        bits.
1067    
1068    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
1069        but did not set the internal JCHANGED flag - either of these is enough to
1070        control the way the "get" function works - but the PCRE_INFO_JCHANGED
1071        facility is supposed to tell if (?J) was ever used, so now (?J) at the
1072        start sets both bits.
1073    
1074    4.  Added options (at build time, compile time, exec time) to change \R from
1075        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
1076    
1077    5.  doc/pcresyntax.html was missing from the distribution.
1078    
1079    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
1080        compatibility, even though it is no longer used.
1081    
1082    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
1083        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
1084        windows.h file is present (where different names are used). [This was
1085        reversed later after testing - see 16 below.]
1086    
1087    8.  Changed all #include <config.h> to #include "config.h". There were also
1088        some further <pcre.h> cases that I changed to "pcre.h".
1089    
1090    9.  When pcregrep was used with the --colour option, it missed the line ending
1091        sequence off the lines that it output.
1092    
1093    10. It was pointed out to me that arrays of string pointers cause lots of
1094        relocations when a shared library is dynamically loaded. A technique of
1095        using a single long string with a table of offsets can drastically reduce
1096        these. I have refactored PCRE in four places to do this. The result is
1097        dramatic:
1098    
1099          Originally:                          290
1100          After changing UCP table:            187
1101          After changing error message table:   43
1102          After changing table of "verbs"       36
1103          After changing table of Posix names   22
1104    
1105        Thanks to the folks working on Gregex for glib for this insight.
1106    
1107    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
1108        unicode-properties was also set.
1109    
1110    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
1111    
1112    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
1113        checked only for CRLF.
1114    
1115    14. Added casts to pcretest.c to avoid compiler warnings.
1116    
1117    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
1118    
1119    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
1120        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
1121        entirely. This removes changes made in 7 above.
1122    
1123    17. The CMake files have been updated, and there is now more information about
1124        building with CMake in the NON-UNIX-USE document.
1125    
1126    
1127    Version 7.3 28-Aug-07
1128    ---------------------
1129    
1130     1. In the rejigging of the build system that eventually resulted in 7.1, the
1131        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
1132        brackets there is not right, since it causes compilers to look for an
1133        installed pcre.h, not the version that is in the source that is being
1134        compiled (which of course may be different). I have changed it back to:
1135    
1136          #include "pcre.h"
1137    
1138        I have a vague recollection that the change was concerned with compiling in
1139        different directories, but in the new build system, that is taken care of
1140        by the VPATH setting the Makefile.
1141    
1142     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
1143        when the subject happened to end in the byte 0x85 (e.g. if the last
1144        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
1145        characters but of course it shouldn't be taken as a newline when it is part
1146        of another character. The bug was that, for an unlimited repeat of . in
1147        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
1148        characters when looking for a newline.
1149    
1150     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
1151    
1152     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
1153        in debug output.
1154    
1155     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
1156        long printing in the pcrecpp unittest when running under MinGW.
1157    
1158     6. ESC_K was left out of the EBCDIC table.
1159    
1160     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
1161        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
1162        limit also applies to "virtual nesting" when a pattern is recursive, and in
1163        this case 1000 isn't so big. I have been able to remove this limit at the
1164        expense of backing off one optimization in certain circumstances. Normally,
1165        when pcre_exec() would call its internal match() function recursively and
1166        immediately return the result unconditionally, it uses a "tail recursion"
1167        feature to save stack. However, when a subpattern that can match an empty
1168        string has an unlimited repetition quantifier, it no longer makes this
1169        optimization. That gives it a stack frame in which to save the data for
1170        checking that an empty string has been matched. Previously this was taken
1171        from the 1000-entry workspace that had been reserved. So now there is no
1172        explicit limit, but more stack is used.
1173    
1174     8. Applied Daniel's patches to solve problems with the import/export magic
1175        syntax that is required for Windows, and which was going wrong for the
1176        pcreposix and pcrecpp parts of the library. These were overlooked when this
1177        problem was solved for the main library.
1178    
1179     9. There were some crude static tests to avoid integer overflow when computing
1180        the size of patterns that contain repeated groups with explicit upper
1181        limits. As the maximum quantifier is 65535, the maximum group length was
1182        set at 30,000 so that the product of these two numbers did not overflow a
1183        32-bit integer. However, it turns out that people want to use groups that
1184        are longer than 30,000 bytes (though not repeat them that many times).
1185        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
1186        made it possible to implement the integer overflow checks in a much more
1187        dynamic way, which I have now done. The artificial limitation on group
1188        length has been removed - we now have only the limit on the total length of
1189        the compiled pattern, which depends on the LINK_SIZE setting.
1190    
1191    10. Fixed a bug in the documentation for get/copy named substring when
1192        duplicate names are permitted. If none of the named substrings are set, the
1193        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
1194        empty string.
1195    
1196    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
1197        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
1198        because the ] is interpreted as the first data character and the
1199        terminating ] is not found. PCRE has been made compatible with Perl in this
1200        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
1201        cause memory overwriting.
1202    
1203    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
1204        string has been matched (to stop an infinite loop). It was not recognizing
1205        a conditional subpattern that could match an empty string if that
1206        subpattern was within another subpattern. For example, it looped when
1207        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
1208        condition was not nested. This bug has been fixed.
1209    
1210    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
1211        past the start of the subject in the presence of bytes with the top bit
1212        set, for example "\x8aBCD".
1213    
1214    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
1215        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
1216    
1217    14. Optimized (?!) to (*FAIL).
1218    
1219    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
1220        This restricts code points to be within the range 0 to 0x10FFFF, excluding
1221        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
1222        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
1223        does: it's just the validity check that is more restrictive.
1224    
1225    16. Inserted checks for integer overflows during escape sequence (backslash)
1226        processing, and also fixed erroneous offset values for syntax errors during
1227        backslash processing.
1228    
1229    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
1230        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
1231    
1232    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
1233        caused an overrun.
1234    
1235    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
1236        something other than just ASCII characters) inside a group that had an
1237        unlimited repeat caused a loop at compile time (while checking to see
1238        whether the group could match an empty string).
1239    
1240    20. Debugging a pattern containing \p or \P could cause a crash. For example,
1241        [\P{Any}] did so. (Error in the code for printing property names.)
1242    
1243    21. An orphan \E inside a character class could cause a crash.
1244    
1245    22. A repeated capturing bracket such as (A)? could cause a wild memory
1246        reference during compilation.
1247    
1248    23. There are several functions in pcre_compile() that scan along a compiled
1249        expression for various reasons (e.g. to see if it's fixed length for look
1250        behind). There were bugs in these functions when a repeated \p or \P was
1251        present in the pattern. These operators have additional parameters compared
1252        with \d, etc, and these were not being taken into account when moving along
1253        the compiled data. Specifically:
1254    
1255        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
1256            length.
1257    
1258        (b) An item such as \pL+ within a repeated group could cause crashes or
1259            loops.
1260    
1261        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
1262            "reference to non-existent subpattern" error.
1263    
1264        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
1265    
1266    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
1267        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
1268    
1269    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
1270    
1271    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
1272        character were causing crashes (broken optimization).
1273    
1274    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
1275        \p or \P) caused a compile-time loop.
1276    
1277    28. More problems have arisen in unanchored patterns when CRLF is a valid line
1278        break. For example, the unstudied pattern [\r\n]A does not match the string
1279        "\r\nA" because change 7.0/46 below moves the current point on by two
1280        characters after failing to match at the start. However, the pattern \nA
1281        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
1282        the same is true. There doesn't seem any very clean way out of this, but
1283        what I have chosen to do makes the common cases work: PCRE now takes note
1284        of whether there can be an explicit match for \r or \n anywhere in the
1285        pattern, and if so, 7.0/46 no longer applies. As part of this change,
1286        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
1287        pattern has explicit CR or LF references.
1288    
1289    29. Added (*CR) etc for changing newline setting at start of pattern.
1290    
1291    
1292    Version 7.2 19-Jun-07
1293    ---------------------
1294    
1295     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
1296        which is apparently normally available under Windows.
1297    
1298     2. Re-jig the pcregrep tests with different newline settings in an attempt
1299        to make them independent of the local environment's newline setting.
1300    
1301     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
1302    
1303     4. Some of the "internals" tests were previously cut out when the link size
1304        was not 2, because the output contained actual offsets. The recent new
1305        "Z" feature of pcretest means that these can be cut out, making the tests
1306        usable with all link sizes.
1307    
1308     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
1309        stack recursion. This gives a massive performance boost under BSD, but just
1310        a small improvement under Linux. However, it saves one field in the frame
1311        in all cases.
1312    
1313     6. Added more features from the forthcoming Perl 5.10:
1314    
1315        (a) (?-n) (where n is a string of digits) is a relative subroutine or
1316            recursion call. It refers to the nth most recently opened parentheses.
1317    
1318        (b) (?+n) is also a relative subroutine call; it refers to the nth next
1319            to be opened parentheses.
1320    
1321        (c) Conditions that refer to capturing parentheses can be specified
1322            relatively, for example, (?(-2)... or (?(+3)...
1323    
1324        (d) \K resets the start of the current match so that everything before
1325            is not part of it.
1326    
1327        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
1328    
1329        (f) \g{name} is another synonym - part of Perl 5.10's unification of
1330            reference syntax.
1331    
1332        (g) (?| introduces a group in which the numbering of parentheses in each
1333            alternative starts with the same number.
1334    
1335        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
1336    
1337     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
1338        PCRE_INFO_JCHANGED.
1339    
1340     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
1341        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
1342        for detecting groups that can match an empty string.
1343    
1344     9. A pattern with a very large number of alternatives (more than several
1345        hundred) was running out of internal workspace during the pre-compile
1346        phase, where pcre_compile() figures out how much memory will be needed. A
1347        bit of new cunning has reduced the workspace needed for groups with
1348        alternatives. The 1000-alternative test pattern now uses 12 bytes of
1349        workspace instead of running out of the 4096 that are available.
1350    
1351    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
1352    
1353    11. Applied patch from Google to remove an optimization that didn't quite work.
1354        The report of the bug said:
1355    
1356          pcrecpp::RE("a*").FullMatch("aaa") matches, while
1357          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
1358          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
1359    
1360    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
1361        it matched the wrong number of bytes.
1362    
1363    
1364    Version 7.1 24-Apr-07
1365    ---------------------
1366    
1367     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
1368        that is more "standard", making use of automake and other Autotools. There
1369        is some re-arrangement of the files and adjustment of comments consequent
1370        on this.
1371    
1372     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
1373        for recursive directory scanning broke on some systems because the files
1374        are not scanned in any specific order and on different systems the order
1375        was different. A call to "sort" has been inserted into RunGrepTest for the
1376        approprate test as a short-term fix. In the longer term there may be an
1377        alternative.
1378    
1379     3. I had an email from Eric Raymond about problems translating some of PCRE's
1380        man pages to HTML (despite the fact that I distribute HTML pages, some
1381        people do their own conversions for various reasons). The problems
1382        concerned the use of low-level troff macros .br and .in. I have therefore
1383        removed all such uses from the man pages (some were redundant, some could
1384        be replaced by .nf/.fi pairs). The 132html script that I use to generate
1385        HTML has been updated to handle .nf/.fi and to complain if it encounters
1386        .br or .in.
1387    
1388     4. Updated comments in configure.ac that get placed in config.h.in and also
1389        arranged for config.h to be included in the distribution, with the name
1390        config.h.generic, for the benefit of those who have to compile without
1391        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
1392    
1393     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
1394        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
1395        makevp.bat for the current PCRE, using the additional files
1396        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
1397    
1398     6. A Windows user reported a minor discrepancy with test 2, which turned out
1399        to be caused by a trailing space on an input line that had got lost in his
1400        copy. The trailing space was an accident, so I've just removed it.
1401    
1402     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
1403        that is needed.
1404    
1405     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
1406        as "const" (a) because they are and (b) because it helps the PHP
1407        maintainers who have recently made a script to detect big data structures
1408        in the php code that should be moved to the .rodata section. I remembered
1409        to update Builducptable as well, so it won't revert if ucptable.h is ever
1410        re-created.
1411    
1412     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
1413        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
1414        order to be able to cut out the UTF-8 tables in the latter when UTF-8
1415        support is not required. This saves 1.5-2K of code, which is important in
1416        some applications.
1417    
1418        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
1419        so as not to refer to the tables, even though these functions will never be
1420        called when UTF-8 support is disabled. Otherwise there are problems with a
1421        shared library.
1422    
1423    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
1424    
1425        (a) It was defining its arguments as char * instead of void *.
1426    
1427        (b) It was assuming that all moves were upwards in memory; this was true
1428            a long time ago when I wrote it, but is no longer the case.
1429    
1430        The emulated memove() is provided for those environments that have neither
1431        memmove() nor bcopy(). I didn't think anyone used it these days, but that
1432        is clearly not the case, as these two bugs were recently reported.
1433    
1434    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
1435        and Detrail to create the HTML documentation, the .txt form of the man
1436        pages, and it removes trailing spaces from listed files. It also creates
1437        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
1438        case, it wraps all the #defines with #ifndefs. This script should be run
1439        before "make dist".
1440    
1441    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
1442        with Unicode property support.
1443    
1444        (a) For a maximizing quantifier, if the two different cases of the
1445            character were of different lengths in their UTF-8 codings (there are
1446            some cases like this - I found 11), and the matching function had to
1447            back up over a mixture of the two cases, it incorrectly assumed they
1448            were both the same length.
1449    
1450        (b) When PCRE was configured to use the heap rather than the stack for
1451            recursion during matching, it was not correctly preserving the data for
1452            the other case of a UTF-8 character when checking ahead for a match
1453            while processing a minimizing repeat. If the check also involved
1454            matching a wide character, but failed, corruption could cause an
1455            erroneous result when trying to check for a repeat of the original
1456            character.
1457    
1458    13. Some tidying changes to the testing mechanism:
1459    
1460        (a) The RunTest script now detects the internal link size and whether there
1461            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
1462            values substituted by "configure". (The RunGrepTest script already did
1463            this for UTF-8.) The configure.ac script no longer substitutes the
1464            relevant variables.
1465    
1466        (b) The debugging options /B and /D in pcretest show the compiled bytecode
1467            with length and offset values. This means that the output is different
1468            for different internal link sizes. Test 2 is skipped for link sizes
1469            other than 2 because of this, bypassing the problem. Unfortunately,
1470            there was also a test in test 3 (the locale tests) that used /B and
1471            failed for link sizes other than 2. Rather than cut the whole test out,
1472            I have added a new /Z option to pcretest that replaces the length and
1473            offset values with spaces. This is now used to make test 3 independent
1474            of link size. (Test 2 will be tidied up later.)
1475    
1476    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
1477        segmentation fault instead of returning the appropriate error message.
1478    
1479    15. In multiline mode when the newline sequence was set to "any", the pattern
1480        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
1481        This doesn't seem right; it now treats the CRLF combination as the line
1482        ending, and so does not match in that case. It's only a pattern such as ^$
1483        that would hit this one: something like ^ABC$ would have failed after \r
1484        and then tried again after \r\n.
1485    
1486    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
1487        in an attempt to make files that differ only in their line terminators
1488        compare equal. This works on Linux.
1489    
1490    17. Under certain error circumstances pcregrep might try to free random memory
1491        as it exited. This is now fixed, thanks to valgrind.
1492    
1493    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
1494        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
1495        was because its rules for how to advance for /g after matching an empty
1496        string at the end of a line did not allow for this case. They now check for
1497        it specially.
1498    
1499    20. pcretest is supposed to handle patterns and data of any length, by
1500        extending its buffers when necessary. It was getting this wrong when the
1501        buffer for a data line had to be extended.
1502    
1503    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
1504        CRLF as a newline sequence.
1505    
1506    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
1507        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
1508        I have nevertheless tidied it up.
1509    
1510    23. Added some casts to kill warnings from HP-UX ia64 compiler.
1511    
1512    24. Added a man page for pcre-config.
1513    
1514    
1515    Version 7.0 19-Dec-06
1516    ---------------------
1517    
1518     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
1519        moving to gcc 4.1.1.
1520    
1521     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
1522        sys/time.h, which is documented as needed for this function. It doesn't
1523        seem to matter on Linux, but it showed up on some releases of OS X.
1524    
1525     3. It seems that there are systems where bytes whose values are greater than
1526        127 match isprint() in the "C" locale. The "C" locale should be the
1527        default when a C program starts up. In most systems, only ASCII printing
1528        characters match isprint(). This difference caused the output from pcretest
1529        to vary, making some of the tests fail. I have changed pcretest so that:
1530    
1531        (a) When it is outputting text in the compiled version of a pattern, bytes
1532            other than 32-126 are always shown as hex escapes.
1533    
1534        (b) When it is outputting text that is a matched part of a subject string,
1535            it does the same, unless a different locale has been set for the match
1536            (using the /L modifier). In this case, it uses isprint() to decide.
1537    
1538     4. Fixed a major bug that caused incorrect computation of the amount of memory
1539        required for a compiled pattern when options that changed within the
1540        pattern affected the logic of the preliminary scan that determines the
1541        length. The relevant options are -x, and -i in UTF-8 mode. The result was
1542        that the computed length was too small. The symptoms of this bug were
1543        either the PCRE error "internal error: code overflow" from pcre_compile(),
1544        or a glibc crash with a message such as "pcretest: free(): invalid next
1545        size (fast)". Examples of patterns that provoked this bug (shown in
1546        pcretest format) are:
1547    
1548          /(?-x: )/x
1549          /(?x)(?-x: \s*#\s*)/
1550          /((?i)[\x{c0}])/8
1551          /(?i:[\x{c0}])/8
1552    
1553        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
1554        is now done differently.
1555    
1556     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
1557        wrapper classes; (b) implement a new function in the C++ scanner that is
1558        more efficient than the old way of doing things because it avoids levels of
1559        recursion in the regex matching; (c) add a paragraph to the documentation
1560        for the FullMatch() function.
1561    
1562     6. The escape sequence \n was being treated as whatever was defined as
1563        "newline". Not only was this contrary to the documentation, which states
1564        that \n is character 10 (hex 0A), but it also went horribly wrong when
1565        "newline" was defined as CRLF. This has been fixed.
1566    
1567     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
1568        was being set to -1 for the "end of line" case (supposedly a value that no
1569        character can have). Though this value is never used (the check for end of
1570        line is "zero bytes in current character"), it caused compiler complaints.
1571        I've changed it to 0xffffffff.
1572    
1573     8. In pcre_version.c, the version string was being built by a sequence of
1574        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
1575        string (as it is for production releases) called a macro with an empty
1576        argument. The C standard says the result of this is undefined. The gcc
1577        compiler treats it as an empty string (which was what was wanted) but it is
1578        reported that Visual C gives an error. The source has been hacked around to
1579        avoid this problem.
1580    
1581     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
1582        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
1583        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
1584        of them did).
1585    
1586    10. Originally, pcretest opened its input and output without "b"; then I was
1587        told that "b" was needed in some environments, so it was added for release
1588        5.0 to both the input and output. (It makes no difference on Unix-like
1589        systems.) Later I was told that it is wrong for the input on Windows. I've
1590        now abstracted the modes into two macros, to make it easier to fiddle with
1591        them, and removed "b" from the input mode under Windows.
1592    
1593    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
1594    
1595    12. Added -help and --help to pcretest as an official way of being reminded
1596        of the options.
1597    
1598    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
1599        and pcrecpp.cc because they annoy compilers at high warning levels.
1600    
1601    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
1602    
1603    15. Fixed an occurrence of == in configure.ac that should have been = (shell
1604        scripts are not C programs :-) and which was not noticed because it works
1605        on Linux.
1606    
1607    16. pcretest is supposed to handle any length of pattern and data line (as one
1608        line or as a continued sequence of lines) by extending its input buffer if
1609        necessary. This feature was broken for very long pattern lines, leading to
1610        a string of junk being passed to pcre_compile() if the pattern was longer
1611        than about 50K.
1612    
1613    17. I have done a major re-factoring of the way pcre_compile() computes the
1614        amount of memory needed for a compiled pattern. Previously, there was code
1615        that made a preliminary scan of the pattern in order to do this. That was
1616        OK when PCRE was new, but as the facilities have expanded, it has become
1617        harder and harder to keep it in step with the real compile phase, and there
1618        have been a number of bugs (see for example, 4 above). I have now found a
1619        cunning way of running the real compile function in a "fake" mode that
1620        enables it to compute how much memory it would need, while actually only
1621        ever using a few hundred bytes of working memory and without too many
1622        tests of the mode. This should make future maintenance and development
1623        easier. A side effect of this work is that the limit of 200 on the nesting
1624        depth of parentheses has been removed (though this was never a serious
1625        limitation, I suspect). However, there is a downside: pcre_compile() now
1626        runs more slowly than before (30% or more, depending on the pattern). I
1627        hope this isn't a big issue. There is no effect on runtime performance.
1628    
1629    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
1630        newline (only possible for the last line of a file) and it was a
1631        pattern that set a locale (followed by /Lsomething), pcretest crashed.
1632    
1633    19. Added additional timing features to pcretest. (1) The -tm option now times
1634        matching only, not compiling. (2) Both -t and -tm can be followed, as a
1635        separate command line item, by a number that specifies the number of
1636        repeats to use when timing. The default is 50000; this gives better
1637        precision, but takes uncomfortably long for very large patterns.
1638    
1639    20. Extended pcre_study() to be more clever in cases where a branch of a
1640        subpattern has no definite first character. For example, (a*|b*)[cd] would
1641        previously give no result from pcre_study(). Now it recognizes that the
1642        first character must be a, b, c, or d.
1643    
1644    21. There was an incorrect error "recursive call could loop indefinitely" if
1645        a subpattern (or the entire pattern) that was being tested for matching an
1646        empty string contained only one non-empty item after a nested subpattern.
1647        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
1648        incorrectly, because the \d was being skipped in the check.
1649    
1650    22. The pcretest program now has a new pattern option /B and a command line
1651        option -b, which is equivalent to adding /B to every pattern. This causes
1652        it to show the compiled bytecode, without the additional information that
1653        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
1654        is the same as /B/I).
1655    
1656    23. A new optimization is now able automatically to treat some sequences such
1657        as a*b as a*+b. More specifically, if something simple (such as a character
1658        or a simple class like \d) has an unlimited quantifier, and is followed by
1659        something that cannot possibly match the quantified thing, the quantifier
1660        is automatically "possessified".
1661    
1662    24. A recursive reference to a subpattern whose number was greater than 39
1663        went wrong under certain circumstances in UTF-8 mode. This bug could also
1664        have affected the operation of pcre_study().
1665    
1666    25. Realized that a little bit of performance could be had by replacing
1667        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
1668    
1669    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
1670    
1671    27. Possessive quantifiers such as a++ were previously implemented by turning
1672        them into atomic groups such as ($>a+). Now they have their own opcodes,
1673        which improves performance. This includes the automatically created ones
1674        from 23 above.
1675    
1676    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
1677        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
1678        the first matched character to be a colon. This applied both to named and
1679        numbered groups.
1680    
1681    29. The ucpinternal.h header file was missing its idempotency #ifdef.
1682    
1683    30. I was sent a "project" file called libpcre.a.dev which I understand makes
1684        building PCRE on Windows easier, so I have included it in the distribution.
1685    
1686    31. There is now a check in pcretest against a ridiculously large number being
1687        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
1688        loop, the loop is abandoned.
1689    
1690    32. Forward references to subpatterns in conditions such as (?(2)...) where
1691        subpattern 2 is defined later cause pcre_compile() to search forwards in
1692        the pattern for the relevant set of parentheses. This search went wrong
1693        when there were unescaped parentheses in a character class, parentheses
1694        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
1695    
1696    33. "Subroutine" calls and backreferences were previously restricted to
1697        referencing subpatterns earlier in the regex. This restriction has now
1698        been removed.
1699    
1700    34. Added a number of extra features that are going to be in Perl 5.10. On the
1701        whole, these are just syntactic alternatives for features that PCRE had
1702        previously implemented using the Python syntax or my own invention. The
1703        other formats are all retained for compatibility.
1704    
1705        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
1706            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
1707            also .NET compatible.
1708    
1709        (b) A recursion or subroutine call to a named group can now be defined as
1710            (?&name) as well as (?P>name).
1711    
1712        (c) A backreference to a named group can now be defined as \k<name> or
1713            \k'name' as well as (?P=name). The new forms, as well as being in Perl
1714            5.10, are also .NET compatible.
1715    
1716        (d) A conditional reference to a named group can now use the syntax
1717            (?(<name>) or (?('name') as well as (?(name).
1718    
1719        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
1720            groups (named and numbered) that are never evaluated inline, but can be
1721            called as "subroutines" from elsewhere. In effect, the DEFINE condition
1722            is always false. There may be only one alternative in such a group.
1723    
1724        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
1725            as the simple (?(R). The condition is true only if the most recent
1726            recursion is that of the given number or name. It does not search out
1727            through the entire recursion stack.
1728    
1729        (g) The escape \gN or \g{N} has been added, where N is a positive or
1730            negative number, specifying an absolute or relative reference.
1731    
1732    35. Tidied to get rid of some further signed/unsigned compiler warnings and
1733        some "unreachable code" warnings.
1734    
1735    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
1736        things, this adds five new scripts.
1737    
1738    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
1739        There were also incompatibilities regarding the handling of \Q..\E inside
1740        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
1741        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
1742    
1743    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
1744        matches an empty string, and forcibly breaks the loop. There were bugs in
1745        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
1746        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
1747        separate and independent bugs (that affected different cases) have been
1748        fixed.
1749    
1750    39. Refactored the code to abolish the use of different opcodes for small
1751        capturing bracket numbers. This is a tidy that I avoided doing when I
1752        removed the limit on the number of capturing brackets for 3.5 back in 2001.
1753        The new approach is not only tidier, it makes it possible to reduce the
1754        memory needed to fix the previous bug (38).
1755    
1756    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
1757        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
1758        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
1759        mode.
1760    
1761    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
1762        report.
1763    
1764    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
1765        copy construction and assignment in the C++ wrapper.
1766    
1767    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
1768        couple of bugs that could have given wrong results in the "--newline=crlf"
1769        case.
1770    
1771    44. Added a number of casts and did some reorganization of signed/unsigned int
1772        variables following suggestions from Dair Grant. Also renamed the variable
1773        "this" as "item" because it is a C++ keyword.
1774    
1775    45. Arranged for dftables to add
1776    
1777          #include "pcre_internal.h"
1778    
1779        to pcre_chartables.c because without it, gcc 4.x may remove the array
1780        definition from the final binary if PCRE is built into a static library and
1781        dead code stripping is activated.
1782    
1783    46. For an unanchored pattern, if a match attempt fails at the start of a
1784        newline sequence, and the newline setting is CRLF or ANY, and the next two
1785        characters are CRLF, advance by two characters instead of one.
1786    
1787    
1788    Version 6.7 04-Jul-06
1789    ---------------------
1790    
1791     1. In order to handle tests when input lines are enormously long, pcretest has
1792        been re-factored so that it automatically extends its buffers when
1793        necessary. The code is crude, but this _is_ just a test program. The
1794        default size has been increased from 32K to 50K.
1795    
1796     2. The code in pcre_study() was using the value of the re argument before
1797        testing it for NULL. (Of course, in any sensible call of the function, it
1798        won't be NULL.)
1799    
1800     3. The memmove() emulation function in pcre_internal.h, which is used on
1801        systems that lack both memmove() and bcopy() - that is, hardly ever -
1802        was missing a "static" storage class specifier.
1803    
1804     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
1805        containing an extended class (one that cannot be represented by a bitmap
1806        because it contains high-valued characters or Unicode property items, e.g.
1807        [\pZ]). Almost always one would set UTF-8 mode when processing such a
1808        pattern, but PCRE should not loop if you do not (it no longer does).
1809        [Detail: two cases were found: (a) a repeated subpattern containing an
1810        extended class; (b) a recursive reference to a subpattern that followed a
1811        previous extended class. It wasn't skipping over the extended class
1812        correctly when UTF-8 mode was not set.]
1813    
1814     5. A negated single-character class was not being recognized as fixed-length
1815        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
1816        compile error "lookbehind assertion is not fixed length".
1817    
1818     6. The RunPerlTest auxiliary script was showing an unexpected difference
1819        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
1820        write a Perl script that can interpret lines of an input file either as
1821        byte characters or as UTF-8, which is what "perltest" was being required to
1822        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
1823        can't do is switch easily at run time between having the "use utf8;" pragma
1824        or not. In the end, I fudged it by using the RunPerlTest script to insert
1825        "use utf8;" explicitly for the UTF-8 tests.
1826    
1827     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
1828        the end of the subject string, contrary to the documentation and to what
1829        Perl does. This was true of both matching functions. Now it matches only at
1830        the start of the subject and immediately after *internal* newlines.
1831    
1832     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
1833        a pointer to an int instead of a pointer to an unsigned long int. This
1834        caused problems on 64-bit systems.
1835    
1836     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
1837        instance of the 'standard' template library not being so standard".
1838    
1839    10. There was no check on the number of named subpatterns nor the maximum
1840        length of a subpattern name. The product of these values is used to compute
1841        the size of the memory block for a compiled pattern. By supplying a very
1842        long subpattern name and a large number of named subpatterns, the size
1843        computation could be caused to overflow. This is now prevented by limiting
1844        the length of names to 32 characters, and the number of named subpatterns
1845        to 10,000.
1846    
1847    11. Subpatterns that are repeated with specific counts have to be replicated in
1848        the compiled pattern. The size of memory for this was computed from the
1849        length of the subpattern and the repeat count. The latter is limited to
1850        65535, but there was no limit on the former, meaning that integer overflow
1851        could in principle occur. The compiled length of a repeated subpattern is
1852        now limited to 30,000 bytes in order to prevent this.
1853    
1854    12. Added the optional facility to have named substrings with the same name.
1855    
1856    13. Added the ability to use a named substring as a condition, using the
1857        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
1858        are numbers (not recommended). Forward references are permitted.
1859    
1860    14. Added forward references in named backreferences (if you see what I mean).
1861    
1862    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
1863        pattern could run off the end of the subject. For example, the pattern
1864        "(?s)(.{1,5})"8 did this with the subject "ab".
1865    
1866    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
1867        PCRE_CASELESS was set when matching characters that were quantified with ?
1868        or *.
1869    
1870    17. A character class other than a single negated character that had a minimum
1871        but no maximum quantifier - for example [ab]{6,} - was not handled
1872        correctly by pce_dfa_exec(). It would match only one character.
1873    
1874    18. A valid (though odd) pattern that looked like a POSIX character
1875        class but used an invalid character after [ (for example [[,abc,]]) caused
1876        pcre_compile() to give the error "Failed: internal error: code overflow" or
1877        in some cases to crash with a glibc free() error. This could even happen if
1878        the pattern terminated after [[ but there just happened to be a sequence of
1879        letters, a binary zero, and a closing ] in the memory that followed.
1880    
1881    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
1882        over the years. Originally (before any Unicode support), just the bottom 8
1883        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
1884        output from "man perlunicode" includes this:
1885    
1886          The regular expression compiler produces polymorphic opcodes.  That
1887          is, the pattern adapts to the data and automatically switches to
1888          the Unicode character scheme when presented with Unicode data--or
1889          instead uses a traditional byte scheme when presented with byte
1890          data.
1891    
1892        Sadly, a wide octal escape does not cause a switch, and in a string with
1893        no other multibyte characters, these octal escapes are treated as before.
1894        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
1895        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
1896        Unicode string.
1897    
1898        I have not perpetrated such confusion in PCRE. Up till now, it took just
1899        the bottom 8 bits, as in old Perl. I have now made octal escapes with
1900        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
1901        translate to the appropriate multibyte character.
1902    
1903    29. Applied some refactoring to reduce the number of warnings from Microsoft
1904        and Borland compilers. This has included removing the fudge introduced
1905        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
1906        a warning about an unused variable.
1907    
1908    21. PCRE has not included VT (character 0x0b) in the set of whitespace
1909        characters since release 4.0, because Perl (from release 5.004) does not.
1910        [Or at least, is documented not to: some releases seem to be in conflict
1911        with the documentation.] However, when a pattern was studied with
1912        pcre_study() and all its branches started with \s, PCRE still included VT
1913        as a possible starting character. Of course, this did no harm; it just
1914        caused an unnecessary match attempt.
1915    
1916    22. Removed a now-redundant internal flag bit that recorded the fact that case
1917        dependency changed within the pattern. This was once needed for "required
1918        byte" processing, but is no longer used. This recovers a now-scarce options
1919        bit. Also moved the least significant internal flag bit to the most-
1920        significant bit of the word, which was not previously used (hangover from
1921        the days when it was an int rather than a uint) to free up another bit for
1922        the future.
1923    
1924    23. Added support for CRLF line endings as well as CR and LF. As well as the
1925        default being selectable at build time, it can now be changed at runtime
1926        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
1927        specify that it is scanning data with non-default line endings.
1928    
1929    24. Changed the definition of CXXLINK to make it agree with the definition of
1930        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
1931    
1932    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
1933        recursions. This makes a big different to stack usage for some patterns.
1934    
1935    26. If a subpattern containing a named recursion or subroutine reference such
1936        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
1937        the space required for the compiled pattern went wrong and gave too small a
1938        value. Depending on the environment, this could lead to "Failed: internal
1939        error: code overflow at offset 49" or "glibc detected double free or
1940        corruption" errors.
1941    
1942    27. Applied patches from Google (a) to support the new newline modes and (b) to
1943        advance over multibyte UTF-8 characters in GlobalReplace.
1944    
1945    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
1946        difference for some implementation of PCRE in some Windows version.
1947    
1948    29. Added some extra testing facilities to pcretest:
1949    
1950        \q<number>   in a data line sets the "match limit" value
1951        \Q<number>   in a data line sets the "match recursion limt" value
1952        -S <number>  sets the stack size, where <number> is in megabytes
1953    
1954        The -S option isn't available for Windows.
1955    
1956    
1957    Version 6.6 06-Feb-06
1958    ---------------------
1959    
1960     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
1961        in pcreposix.h. I have copied the definition from pcre.h.
1962    
1963     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
1964        because pcre.h is no longer a built file.
1965    
1966     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
1967        not normally included in the compiled code.
1968    
1969    
1970    Version 6.5 01-Feb-06
1971    ---------------------
1972    
1973     1. When using the partial match feature with pcre_dfa_exec(), it was not
1974        anchoring the second and subsequent partial matches at the new starting
1975        point. This could lead to incorrect results. For example, with the pattern
1976        /1234/, partially matching against "123" and then "a4" gave a match.
1977    
1978     2. Changes to pcregrep:
1979    
1980        (a) All non-match returns from pcre_exec() were being treated as failures
1981            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
1982            error message is output. Some extra information is given for the
1983            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
1984            probably the only errors that are likely to be caused by users (by
1985            specifying a regex that has nested indefinite repeats, for instance).
1986            If there are more than 20 of these errors, pcregrep is abandoned.
1987    
1988        (b) A binary zero was treated as data while matching, but terminated the
1989            output line if it was written out. This has been fixed: binary zeroes
1990            are now no different to any other data bytes.
1991    
1992        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
1993            used to set a locale for matching. The --locale=xxxx long option has
1994            been added (no short equivalent) to specify a locale explicitly on the
1995            pcregrep command, overriding the environment variables.
1996    
1997        (d) When -B was used with -n, some line numbers in the output were one less
1998            than they should have been.
1999    
2000        (e) Added the -o (--only-matching) option.
2001    
2002        (f) If -A or -C was used with -c (count only), some lines of context were
2003            accidentally printed for the final match.
2004    
2005        (g) Added the -H (--with-filename) option.
2006    
2007        (h) The combination of options -rh failed to suppress file names for files
2008            that were found from directory arguments.
2009    
2010        (i) Added the -D (--devices) and -d (--directories) options.
2011    
2012        (j) Added the -F (--fixed-strings) option.
2013    
2014        (k) Allow "-" to be used as a file name for -f as well as for a data file.
2015    
2016        (l) Added the --colo(u)r option.
2017    
2018        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
2019            is not present by default.
2020    
2021     3. A nasty bug was discovered in the handling of recursive patterns, that is,
2022        items such as (?R) or (?1), when the recursion could match a number of
2023        alternatives. If it matched one of the alternatives, but subsequently,
2024        outside the recursion, there was a failure, the code tried to back up into
2025        the recursion. However, because of the way PCRE is implemented, this is not
2026        possible, and the result was an incorrect result from the match.
2027    
2028        In order to prevent this happening, the specification of recursion has
2029        been changed so that all such subpatterns are automatically treated as
2030        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
2031    
2032     4. I had overlooked the fact that, in some locales, there are characters for
2033        which isalpha() is true but neither isupper() nor islower() are true. In
2034        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
2035        and ordfeminine) are like this. This affected the treatment of \w and \W
2036        when they appeared in character classes, but not when they appeared outside
2037        a character class. The bit map for "word" characters is now created
2038        separately from the results of isalnum() instead of just taking it from the
2039        upper, lower, and digit maps. (Plus the underscore character, of course.)
2040    
2041     5. The above bug also affected the handling of POSIX character classes such as
2042        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
2043        permanent tables. Instead, the bit maps for such a class were previously
2044        created as the appropriate unions of the upper, lower, and digit bitmaps.
2045        Now they are created by subtraction from the [[:word:]] class, which has
2046        its own bitmap.
2047    
2048     6. The [[:blank:]] character class matches horizontal, but not vertical space.
2049        It is created by subtracting the vertical space characters (\x09, \x0a,
2050        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
2051        subtraction was done in the overall bitmap for a character class, meaning
2052        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
2053        be recognized. This bug has been fixed.
2054    
2055     7. Patches from the folks at Google:
2056    
2057          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
2058          real life, but is still worth protecting against".
2059    
2060          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
2061          regular expressions".
2062    
2063          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
2064          have it.
2065    
2066          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
2067          "configure" and the latter not, in order to fix a problem somebody had
2068          with compiling the Arg class on HP-UX.
2069    
2070          (e) Improve the error-handling of the C++ wrapper a little bit.
2071    
2072          (f) New tests for checking recursion limiting.
2073    
2074     8. The pcre_memmove() function, which is used only if the environment does not
2075        have a standard memmove() function (and is therefore rarely compiled),
2076        contained two bugs: (a) use of int instead of size_t, and (b) it was not
2077        returning a result (though PCRE never actually uses the result).
2078    
2079     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
2080        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
2081        returned instead of calling malloc() with an overflowing number that would
2082        most likely cause subsequent chaos.
2083    
2084    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
2085    
2086    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
2087        with this option is matched, the nmatch and pmatch options of regexec() are
2088        ignored.
2089    
2090    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
2091        provided in case anyone wants to the the POSIX interface with UTF-8
2092        strings.
2093    
2094    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
2095        C++ linking (needed for some HP-UX environments).
2096    
2097    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
2098        (unused parameter) and in the pcre_printint() function (omitted "default"
2099        switch label when the default is to do nothing).
2100    
2101    15. Added some code to make it possible, when PCRE is compiled as a C++
2102        library, to replace subject pointers for pcre_exec() with a smart pointer
2103        class, thus making it possible to process discontinuous strings.
2104    
2105    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
2106        much the same function. They were added by different people who were trying
2107        to make PCRE easy to compile on non-Unix systems. It has been suggested
2108        that PCRE_EXPORT be abolished now that there is more automatic apparatus
2109        for compiling on Windows systems. I have therefore replaced it with
2110        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
2111        defaults to "extern" for C or "extern C" for C++, which works fine on
2112        Unix-like systems. It is now possible to override the value of PCRE_DATA_
2113        SCOPE with something explicit in config.h. In addition:
2114    
2115        (a) pcreposix.h still had just "extern" instead of either of these macros;
2116            I have replaced it with PCRE_DATA_SCOPE.
2117    
2118        (b) Functions such as _pcre_xclass(), which are internal to the library,
2119            but external in the C sense, all had PCRE_EXPORT in their definitions.
2120            This is apparently wrong for the Windows case, so I have removed it.
2121            (It makes no difference on Unix-like systems.)
2122    
2123    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
2124        of recursive calls to match(). This is different to MATCH_LIMIT because
2125        that limits the total number of calls to match(), not all of which increase
2126        the depth of recursion. Limiting the recursion depth limits the amount of
2127        stack (or heap if NO_RECURSE is set) that is used. The default can be set
2128        when PCRE is compiled, and changed at run time. A patch from Google adds
2129        this functionality to the C++ interface.
2130    
2131    18. Changes to the handling of Unicode character properties:
2132    
2133        (a) Updated the table to Unicode 4.1.0.
2134    
2135        (b) Recognize characters that are not in the table as "Cn" (undefined).
2136    
2137        (c) I revised the way the table is implemented to a much improved format
2138            which includes recognition of ranges. It now supports the ranges that
2139            are defined in UnicodeData.txt, and it also amalgamates other
2140            characters into ranges. This has reduced the number of entries in the
2141            table from around 16,000 to around 3,000, thus reducing its size
2142            considerably. I realized I did not need to use a tree structure after
2143            all - a binary chop search is just as efficient. Having reduced the
2144            number of entries, I extended their size from 6 bytes to 8 bytes to
2145            allow for more data.
2146    
2147        (d) Added support for Unicode script names via properties such as \p{Han}.
2148    
2149    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
2150        matching that character.
2151    
2152    20. When matching a repeated Unicode property with a minimum greater than zero,
2153        (for example \pL{2,}), PCRE could look past the end of the subject if it
2154        reached it while seeking the minimum number of characters. This could
2155        happen only if some of the characters were more than one byte long, because
2156        there is a check for at least the minimum number of bytes.
2157    
2158    21. Refactored the implementation of \p and \P so as to be more general, to
2159        allow for more different types of property in future. This has changed the
2160        compiled form incompatibly. Anybody with saved compiled patterns that use
2161        \p or \P will have to recompile them.
2162    
2163    22. Added "Any" and "L&" to the supported property types.
2164    
2165    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
2166        but give a compile time error if the value is greater than 0xff.
2167    
2168    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
2169        accidentally not being installed or uninstalled.
2170    
2171    25. The pcre.h file was built from pcre.h.in, but the only changes that were
2172        made were to insert the current release number. This seemed silly, because
2173        it made things harder for people building PCRE on systems that don't run
2174        "configure". I have turned pcre.h into a distributed file, no longer built
2175        by "configure", with the version identification directly included. There is
2176        no longer a pcre.h.in file.
2177    
2178        However, this change necessitated a change to the pcre-config script as
2179        well. It is built from pcre-config.in, and one of the substitutions was the
2180        release number. I have updated configure.ac so that ./configure now finds
2181        the release number by grepping pcre.h.
2182    
2183    26. Added the ability to run the tests under valgrind.
2184    
2185    
2186    Version 6.4 05-Sep-05
2187    ---------------------
2188    
2189     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
2190        "--" to be printed when multiple files were scanned, even when none of the
2191        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
2192        consider it to be a bug, and have restored the previous behaviour.
2193    
2194     2. A couple of code tidies to get rid of compiler warnings.
2195    
2196     3. The pcretest program used to cheat by referring to symbols in the library
2197        whose names begin with _pcre_. These are internal symbols that are not
2198        really supposed to be visible externally, and in some environments it is
2199        possible to suppress them. The cheating is now confined to including
2200        certain files from the library's source, which is a bit cleaner.
2201    
2202     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
2203        file's purpose clearer.
2204    
2205     5. Reorganized pcre_ucp_findchar().
2206    
2207    
2208    Version 6.3 15-Aug-05
2209    ---------------------
2210    
2211     1. The file libpcre.pc.in did not have general read permission in the tarball.
2212    
2213     2. There were some problems when building without C++ support:
2214    
2215        (a) If C++ support was not built, "make install" and "make test" still
2216            tried to test it.
2217    
2218        (b) There were problems when the value of CXX was explicitly set. Some
2219            changes have been made to try to fix these, and ...
2220    
2221        (c) --disable-cpp can now be used to explicitly disable C++ support.
2222    
2223        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
2224            backslash in a target when C++ was disabled. This confuses some
2225            versions of "make", apparently. Using an intermediate variable solves
2226            this. (Same for CPP_LOBJ.)
2227    
2228     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
2229        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
2230        necessary on certain architectures.
2231    
2232     4. Added a setting of -export-symbols-regex to the link command to remove
2233        those symbols that are exported in the C sense, but actually are local
2234        within the library, and not documented. Their names all begin with
2235        "_pcre_". This is not a perfect job, because (a) we have to except some
2236        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
2237        available (and never for static libraries). I have made a note to try to
2238        find a way round (a) in the future.
2239    
2240    
2241    Version 6.2 01-Aug-05
2242    ---------------------
2243    
2244     1. There was no test for integer overflow of quantifier values. A construction
2245        such as {1111111111111111} would give undefined results. What is worse, if
2246        a minimum quantifier for a parenthesized subpattern overflowed and became
2247        negative, the calculation of the memory size went wrong. This could have
2248        led to memory overwriting.
2249    
2250     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
2251    
2252     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
2253        operating environments where this matters.
2254    
2255     4. Applied Giuseppe Maxia's patch to add additional features for controlling
2256        PCRE options from within the C++ wrapper.
2257    
2258     5. Named capturing subpatterns were not being correctly counted when a pattern
2259        was compiled. This caused two problems: (a) If there were more than 100
2260        such subpatterns, the calculation of the memory needed for the whole
2261        compiled pattern went wrong, leading to an overflow error. (b) Numerical
2262        back references of the form \12, where the number was greater than 9, were
2263        not recognized as back references, even though there were sufficient
2264        previous subpatterns.
2265    
2266     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
2267        versions of gcc, e.g. 2.95.4.
2268    
2269    
2270    Version 6.1 21-Jun-05
2271    ---------------------
2272    
2273     1. There was one reference to the variable "posix" in pcretest.c that was not
2274        surrounded by "#if !defined NOPOSIX".
2275    
2276     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
2277        the cross-check on the old pcre_info() function, for the benefit of the
2278        cut-down version of PCRE that is currently imported into Exim.
2279    
2280     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
2281        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
2282        patterns that start (?i) but I don't think that matters. The use of (?i) is
2283        just an example; this all applies to the other options as well.
2284    
2285     4. Since libtool seems to echo the compile commands it is issuing, the output
2286        from "make" can be reduced a bit by putting "@" in front of each libtool
2287        compile command.
2288    
2289     5. Patch from the folks at Google for configure.in to be a bit more thorough
2290        in checking for a suitable C++ installation before trying to compile the
2291        C++ stuff. This should fix a reported problem when a compiler was present,
2292        but no suitable headers.
2293    
2294     6. The man pages all had just "PCRE" as their title. I have changed them to
2295        be the relevant file name. I have also arranged that these names are
2296        retained in the file doc/pcre.txt, which is a concatenation in text format
2297        of all the man pages except the little individual ones for each function.
2298    
2299     7. The NON-UNIX-USE file had not been updated for the different set of source
2300        files that come with release 6. I also added a few comments about the C++
2301        wrapper.
2302    
2303    
2304    Version 6.0 07-Jun-05
2305    ---------------------
2306    
2307     1. Some minor internal re-organization to help with my DFA experiments.
2308    
2309     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
2310        didn't matter for the library itself when fully configured, but did matter
2311        when compiling without UCP support, or within Exim, where the ucp files are
2312        not imported.
2313    
2314     3. Refactoring of the library code to split up the various functions into
2315        different source modules. The addition of the new DFA matching code (see
2316        below) to a single monolithic source would have made it really too
2317        unwieldy, quite apart from causing all the code to be include in a
2318        statically linked application, when only some functions are used. This is
2319        relevant even without the DFA addition now that patterns can be compiled in
2320        one application and matched in another.
2321    
2322        The downside of splitting up is that there have to be some external
2323        functions and data tables that are used internally in different modules of
2324        the library but which are not part of the API. These have all had their
2325        names changed to start with "_pcre_" so that they are unlikely to clash
2326        with other external names.
2327    
2328     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
2329        a different (DFA) algorithm. Although it is slower than the original
2330        function, it does have some advantages for certain types of matching
2331        problem.
2332    
2333     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
2334        including restarting after a partial match.
2335    
2336     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
2337        defined when compiling for Windows was sent to me. I have put it into the
2338        code, though I have no means of testing or verifying it.
2339    
2340     7. Added the pcre_refcount() auxiliary function.
2341    
2342     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
2343        match before or at the first newline in the subject string. In pcretest,
2344        the /f option on a pattern can be used to set this.
2345    
2346     9. A repeated \w when used in UTF-8 mode with characters greater than 256
2347        would behave wrongly. This has been present in PCRE since release 4.0.
2348    
2349    10. A number of changes to the pcregrep command:
2350    
2351        (a) Refactored how -x works; insert ^(...)$ instead of setting
2352            PCRE_ANCHORED and checking the length, in preparation for adding
2353            something similar for -w.
2354    
2355        (b) Added the -w (match as a word) option.
2356    
2357        (c) Refactored the way lines are read and buffered so as to have more
2358            than one at a time available.
2359    
2360        (d) Implemented a pcregrep test script.
2361    
2362        (e) Added the -M (multiline match) option. This allows patterns to match
2363            over several lines of the subject. The buffering ensures that at least
2364            8K, or the rest of the document (whichever is the shorter) is available
2365            for matching (and similarly the previous 8K for lookbehind assertions).
2366    
2367        (f) Changed the --help output so that it now says
2368    
2369              -w, --word-regex(p)
2370    
2371            instead of two lines, one with "regex" and the other with "regexp"
2372            because that confused at least one person since the short forms are the
2373            same. (This required a bit of code, as the output is generated
2374            automatically from a table. It wasn't just a text change.)
2375    
2376        (g) -- can be used to terminate pcregrep options if the next thing isn't an
2377            option but starts with a hyphen. Could be a pattern or a path name
2378            starting with a hyphen, for instance.
2379    
2380        (h) "-" can be given as a file name to represent stdin.
2381    
2382        (i) When file names are being printed, "(standard input)" is used for
2383            the standard input, for compatibility with GNU grep. Previously
2384            "<stdin>" was used.
2385    
2386        (j) The option --label=xxx can be used to supply a name to be used for
2387            stdin when file names are being printed. There is no short form.
2388    
2389        (k) Re-factored the options decoding logic because we are going to add
2390            two more options that take data. Such options can now be given in four
2391            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
2392    
2393        (l) Added the -A, -B, and -C options for requesting that lines of context
2394            around matches be printed.
2395    
2396        (m) Added the -L option to print the names of files that do not contain
2397            any matching lines, that is, the complement of -l.
2398    
2399        (n) The return code is 2 if any file cannot be opened, but pcregrep does
2400            continue to scan other files.
2401    
2402        (o) The -s option was incorrectly implemented. For compatibility with other
2403            greps, it now suppresses the error message for a non-existent or non-
2404            accessible file (but not the return code). There is a new option called
2405            -q that suppresses the output of matching lines, which was what -s was
2406            previously doing.
2407    
2408        (p) Added --include and --exclude options to specify files for inclusion
2409            and exclusion when recursing.
2410    
2411    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
2412        Hopefully, it now does.
2413    
2414    12. Missing cast in pcre_study().
2415    
2416    13. Added an "uninstall" target to the makefile.
2417    
2418    14. Replaced "extern" in the function prototypes in Makefile.in with
2419        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
2420        world, but is set differently for Windows.
2421    
2422    15. Added a second compiling function called pcre_compile2(). The only
2423        difference is that it has an extra argument, which is a pointer to an
2424        integer error code. When there is a compile-time failure, this is set
2425        non-zero, in addition to the error test pointer being set to point to an
2426        error message. The new argument may be NULL if no error number is required
2427        (but then you may as well call pcre_compile(), which is now just a
2428        wrapper). This facility is provided because some applications need a
2429        numeric error indication, but it has also enabled me to tidy up the way
2430        compile-time errors are handled in the POSIX wrapper.
2431    
2432    16. Added VPATH=.libs to the makefile; this should help when building with one
2433        prefix path and installing with another. (Or so I'm told by someone who
2434        knows more about this stuff than I do.)
2435    
2436    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
2437        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
2438        match everything, including newlines. This is not POSIX-compatible, but
2439        somebody wanted the feature. From pcretest it can be activated by using
2440        both the P and the s flags.
2441    
2442    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
2443    
2444    19. libpcre.pc was being incorrectly installed as executable.
2445    
2446    20. A couple of places in pcretest check for end-of-line by looking for '\n';
2447        it now also looks for '\r' so that it will work unmodified on Windows.
2448    
2449    21. Added Google's contributed C++ wrapper to the distribution.
2450    
2451    22. Added some untidy missing memory free() calls in pcretest, to keep
2452        Electric Fence happy when testing.
2453    
2454    
2455    
2456    Version 5.0 13-Sep-04
2457    ---------------------
2458    
2459     1. Internal change: literal characters are no longer packed up into items
2460        containing multiple characters in a single byte-string. Each character
2461        is now matched using a separate opcode. However, there may be more than one
2462        byte in the character in UTF-8 mode.
2463    
2464     2. The pcre_callout_block structure has two new fields: pattern_position and
2465        next_item_length. These contain the offset in the pattern to the next match
2466        item, and its length, respectively.
2467    
2468     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
2469        insertion of callouts before each pattern item. Added the /C option to
2470        pcretest to make use of this.
2471    
2472     4. On the advice of a Windows user, the lines
2473    
2474          #if defined(_WIN32) || defined(WIN32)
2475          _setmode( _fileno( stdout ), 0x8000 );
2476          #endif  /* defined(_WIN32) || defined(WIN32) */
2477    
2478        have been added to the source of pcretest. This apparently does useful
2479        magic in relation to line terminators.
2480    
2481     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
2482        for the benefit of those environments where the "b" makes a difference.
2483    
2484     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
2485        to know about it. I have put a hack into configure.in that adds in code
2486        to set GCC=yes if CC=icc. This seems to end up at a point in the
2487        generated configure script that is early enough to affect the setting of
2488        compiler options, which is what is needed, but I have no means of testing
2489        whether it really works. (The user who reported this had patched the
2490        generated configure script, which of course I cannot do.)
2491    
2492        LATER: After change 22 below (new libtool files), the configure script
2493        seems to know about icc (and also ecc). Therefore, I have commented out
2494        this hack in configure.in.
2495    
2496     7. Added support for pkg-config (2 patches were sent in).
2497    
2498     8. Negated POSIX character classes that used a combination of internal tables
2499        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
2500        [[:^ascii]]. Typically, they would match almost any characters. The other
2501        POSIX classes were not broken in this way.
2502    
2503     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
2504        to find the match, as PCRE was deluded into thinking that the match had to
2505        start at the start point or following a newline. The same bug applied to
2506        patterns with negative forward assertions or any backward assertions
2507        preceding ".*" at the start, unless the pattern required a fixed first
2508        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
2509    
2510    10. In UTF-8 mode, when moving forwards in the subject after a failed match
2511        starting at the last subject character, bytes beyond the end of the subject
2512        string were read.
2513    
2514    11. Renamed the variable "class" as "classbits" to make life easier for C++
2515        users. (Previously there was a macro definition, but it apparently wasn't
2516        enough.)
2517    
2518    12. Added the new field "tables" to the extra data so that tables can be passed
2519        in at exec time, or the internal tables can be re-selected. This allows
2520        a compiled regex to be saved and re-used at a later time by a different
2521        program that might have everything at different addresses.
2522    
2523    13. Modified the pcre-config script so that, when run on Solaris, it shows a
2524        -R library as well as a -L library.
2525    
2526    14. The debugging options of pcretest (-d on the command line or D on a
2527        pattern) showed incorrect output for anything following an extended class
2528        that contained multibyte characters and which was followed by a quantifier.
2529    
2530    15. Added optional support for general category Unicode character properties
2531        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
2532        support. It adds about 90K to the size of the library. The meanings of the
2533        inbuilt class escapes such as \d and \s have NOT been changed.
2534    
2535    16. Updated pcredemo.c to include calls to free() to release the memory for the
2536        compiled pattern.
2537    
2538    17. The generated file chartables.c was being created in the source directory
2539        instead of in the building directory. This caused the build to fail if the
2540        source directory was different from the building directory, and was
2541        read-only.
2542    
2543    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
2544        file. No doubt somebody will tell me if they don't make sense... Also added
2545        Dan Mooney's comments about building on OpenVMS.
2546    
2547    19. Added support for partial matching via the PCRE_PARTIAL option for
2548        pcre_exec() and the \P data escape in pcretest.
2549    
2550    20. Extended pcretest with 3 new pattern features:
2551    
2552        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
2553              write the compiled pattern to the file whose name is "rest-of-line".
2554              This is a straight binary dump of the data, with the saved pointer to
2555              the character tables forced to be NULL. The study data, if any, is
2556              written too. After writing, pcretest reads a new pattern.
2557    
2558        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
2559              compiled pattern from the given file. There must not be any
2560              occurrences of "<" in the file name (pretty unlikely); if there are,
2561              pcretest will instead treat the initial "<" as a pattern delimiter.
2562              After reading in the pattern, pcretest goes on to read data lines as
2563              usual.
2564    
2565        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
2566              and 16-bit fields in a compiled pattern, to simulate a pattern that
2567              was compiled on a host of opposite endianness.
2568    
2569    21. The pcre-exec() function can now cope with patterns that were compiled on
2570        hosts of opposite endianness, with this restriction:
2571    
2572          As for any compiled expression that is saved and used later, the tables
2573          pointer field cannot be preserved; the extra_data field in the arguments
2574          to pcre_exec() should be used to pass in a tables address if a value
2575          other than the default internal tables were used at compile time.
2576    
2577    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
2578        now diagnosed as an error. Previously, most of the time, a negative number
2579        would have been treated as zero, but if in addition "ovector" was passed as
2580        NULL, a crash could occur.
2581    
2582    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
2583        new versions from the libtool 1.5 distribution (the last one is a copy of
2584        a file called libtool.m4). This seems to have fixed the need to patch
2585        "configure" to support Darwin 1.3 (which I used to do). However, I still
2586        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
2587        workstation).
2588    
2589    24. Changed the PCRE licence to be the more standard "BSD" licence.
2590    
2591    
2592    Version 4.5 01-Dec-03
2593    ---------------------
2594    
2595     1. There has been some re-arrangement of the code for the match() function so
2596        that it can be compiled in a version that does not call itself recursively.
2597        Instead, it keeps those local variables that need separate instances for
2598        each "recursion" in a frame on the heap, and gets/frees frames whenever it
2599        needs to "recurse". Keeping track of where control must go is done by means
2600        of setjmp/longjmp. The whole thing is implemented by a set of macros that
2601        hide most of the details from the main code, and operates only if
2602        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
2603        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
2604        operating.
2605    
2606        To make it easier for callers to provide specially tailored get/free
2607        functions for this usage, two new functions, pcre_stack_malloc, and
2608        pcre_stack_free, are used. They are always called in strict stacking order,
2609        and the size of block requested is always the same.
2610    
2611        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
2612        PCRE has been compiled to use the stack or the heap for recursion. The
2613        -C option of pcretest uses this to show which version is compiled.
2614    
2615        A new data escape \S, is added to pcretest; it causes the amounts of store
2616        obtained and freed by both kinds of malloc/free at match time to be added
2617        to the output.
2618    
2619     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
2620        what's available on my current Linux desktop machine.
2621    
2622     3. When matching a UTF-8 string, the test for a valid string at the start has
2623        been extended. If start_offset is not zero, PCRE now checks that it points
2624        to a byte that is the start of a UTF-8 character. If not, it returns
2625        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
2626        this is necessary because there may be backward assertions in the pattern.
2627        When matching the same subject several times, it may save resources to use
2628        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
2629    
2630     4. The code for checking the validity of UTF-8 strings has been tightened so
2631        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
2632        containing "overlong sequences".
2633    
2634     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
2635        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
2636        should have been "&", but it just so happened that all the cases this let
2637        through by mistake were picked up later in the function.
2638    
2639     6. I had used a variable called "isblank" - this is a C99 function, causing
2640        some compilers to warn. To avoid this, I renamed it (as "blankclass").
2641    
2642     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
2643        prompting; (b) run "./pcretest /dev/null" at the start of the test script
2644        so the version is shown; (c) stop "make test" echoing "./RunTest".
2645    
2646     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
2647    
2648     9. The prototype for memmove() for systems that don't have it was using
2649        size_t, but the inclusion of the header that defines size_t was later. I've
2650        moved the #includes for the C headers earlier to avoid this.
2651    
2652    10. Added some adjustments to the code to make it easier to compiler on certain
2653        special systems:
2654    
2655          (a) Some "const" qualifiers were missing.
2656          (b) Added the macro EXPORT before all exported functions; by default this
2657              is defined to be empty.
2658          (c) Changed the dftables auxiliary program (that builds chartables.c) so
2659              that it reads its output file name as an argument instead of writing
2660              to the standard output and assuming this can be redirected.
2661    
2662    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
2663        class containing characters with values greater than 255, PCRE compilation
2664        went into a loop.
2665    
2666    12. A recursive reference to a subpattern that was within another subpattern
2667        that had a minimum quantifier of zero caused PCRE to crash. For example,
2668        (x(y(?2))z)? provoked this bug with a subject that got as far as the
2669        recursion. If the recursively-called subpattern itself had a zero repeat,
2670        that was OK.
2671    
2672    13. In pcretest, the buffer for reading a data line was set at 30K, but the
2673        buffer into which it was copied (for escape processing) was still set at
2674        1024, so long lines caused crashes.
2675    
2676    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
2677        "internal error: code overflow...". This applied to any character class
2678        that was followed by a possessive quantifier.
2679    
2680    15. Modified the Makefile to add libpcre.la as a prerequisite for
2681        libpcreposix.la because I was told this is needed for a parallel build to
2682        work.
2683    
2684    16. If a pattern that contained .* following optional items at the start was
2685        studied, the wrong optimizing data was generated, leading to matching
2686        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
2687        matching string must start with a or b or c. The correct conclusion for
2688        this pattern is that a match can start with any character.
2689    
2690    
2691    Version 4.4 13-Aug-03
2692    ---------------------
2693    
2694     1. In UTF-8 mode, a character class containing characters with values between
2695        127 and 255 was not handled correctly if the compiled pattern was studied.
2696        In fixing this, I have also improved the studying algorithm for such
2697        classes (slightly).
2698    
2699     2. Three internal functions had redundant arguments passed to them. Removal
2700        might give a very teeny performance improvement.
2701    
2702     3. Documentation bug: the value of the capture_top field in a callout is *one
2703        more than* the number of the hightest numbered captured substring.
2704    
2705     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
2706        in incorrectly linking with a previously installed version. They now link
2707        explicitly with libpcre.la.
2708    
2709     5. configure.in no longer needs to recognize Cygwin specially.
2710    
2711     6. A problem in pcre.in for Windows platforms is fixed.
2712    
2713     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
2714        pcretest, it used to include the size of the study block as part of its
2715        output. Unfortunately, the structure contains a field that has a different
2716        size on different hardware architectures. This meant that the tests that
2717        showed this size failed. As the block is currently always of a fixed size,
2718        this information isn't actually particularly useful in pcretest output, so
2719        I have just removed it.
2720    
2721     8. Three pre-processor statements accidentally did not start in column 1.
2722        Sadly, there are *still* compilers around that complain, even though
2723        standard C has not required this for well over a decade. Sigh.
2724    
2725     9. In pcretest, the code for checking callouts passed small integers in the
2726        callout_data field, which is a void * field. However, some picky compilers
2727        complained about the casts involved for this on 64-bit systems. Now
2728        pcretest passes the address of the small integer instead, which should get
2729        rid of the warnings.
2730    
2731    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
2732        both compile and run time, and gives an error if an invalid UTF-8 sequence
2733        is found. There is a option for disabling this check in cases where the
2734        string is known to be correct and/or the maximum performance is wanted.
2735    
2736    11. In response to a bug report, I changed one line in Makefile.in from
2737    
2738            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
2739        to
2740            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
2741    
2742        to look similar to other lines, but I have no way of telling whether this
2743        is the right thing to do, as I do not use Windows. No doubt I'll get told
2744        if it's wrong...
2745    
2746    
2747    Version 4.3 21-May-03
2748    ---------------------
2749    
2750    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
2751       Makefile.
2752    
2753    2. Some refactoring to improve the quality of the code:
2754    
2755       (i)   The utf8_table... variables are now declared "const".
2756    
2757       (ii)  The code for \cx, which used the "case flipping" table to upper case
2758             lower case letters, now just substracts 32. This is ASCII-specific,
2759             but the whole concept of \cx is ASCII-specific, so it seems
2760             reasonable.
2761    
2762       (iii) PCRE was using its character types table to recognize decimal and
2763             hexadecimal digits in the pattern. This is silly, because it handles
2764             only 0-9, a-f, and A-F, but the character types table is locale-
2765             specific, which means strange things might happen. A private
2766             table is now used for this - though it costs 256 bytes, a table is
2767             much faster than multiple explicit tests. Of course, the standard
2768             character types table is still used for matching digits in subject
2769             strings against \d.
2770    
2771       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
2772             ending in _t are). So I've renamed it as ESC_tee.
2773    
2774    3. The first argument for regexec() in the POSIX wrapper should have been
2775       defined as "const".
2776    
2777    4. Changed pcretest to use malloc() for its buffers so that they can be
2778       Electric Fenced for debugging.
2779    
2780    5. There were several places in the code where, in UTF-8 mode, PCRE would try
2781       to read one or more bytes before the start of the subject string. Often this
2782       had no effect on PCRE's behaviour, but in some circumstances it could
2783       provoke a segmentation fault.
2784    
2785    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
2786       to try to read one or more bytes before the start of the subject string.
2787    
2788    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
2789       UTF-8 support could misbehave in various ways if the subject string
2790       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
2791       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
2792       back over UTF-8 characters.)
2793    
2794    
2795    Version 4.2 14-Apr-03
2796    ---------------------
2797    
2798    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
2799    
2800    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
2801         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
2802         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
2803         [WIN_PREFIX]: new variable, "cyg" for Cygwin
2804         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
2805           and BUILD_EXEEXT
2806         Note: automatic setting of the BUILD variables is not yet working
2807         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
2808           compile-time but not at link-time
2809         [LINK]: use for linking executables only
2810         make different versions for Windows and non-Windows
2811         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
2812           libraries
2813         [LINK_FOR_BUILD]: new variable
2814         [OBJEXT]: use throughout
2815         [EXEEXT]: use throughout
2816         <winshared>: new target
2817         <wininstall>: new target
2818         <dftables.o>: use native compiler
2819         <dftables>: use native linker
2820         <install>: handle Windows platform correctly
2821         <clean>: ditto
2822         <check>: ditto
2823         copy DLL to top builddir before testing
2824    
2825       As part of these changes, -no-undefined was removed again. This was reported
2826       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
2827       in any case.
2828    
2829    3. Some tidies to get rid of compiler warnings:
2830    
2831       . In the match_data structure, match_limit was an unsigned long int, whereas
2832         match_call_count was an int. I've made them both unsigned long ints.
2833    
2834       . In pcretest the fact that a const uschar * doesn't automatically cast to
2835         a void * provoked a warning.
2836    
2837       . Turning on some more compiler warnings threw up some "shadow" variables
2838         and a few more missing casts.
2839    
2840    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
2841       option, a class that contained a single character with a value between 128
2842       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
2843    
2844    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
2845       option, a class that contained several characters, but with at least one
2846       whose value was between 128 and 255 caused PCRE to crash.
2847    
2848    
2849    Version 4.1 12-Mar-03
2850    ---------------------
2851    
2852    1. Compiling with gcc -pedantic found a couple of places where casts were
2853    needed, and a string in dftables.c that was longer than standard compilers are
2854    required to support.
2855    
2856    2. Compiling with Sun's compiler found a few more places where the code could
2857    be tidied up in order to avoid warnings.
2858    
2859    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
2860    first of these names is deprecated in the latest Autoconf in favour of the name
2861    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
2862    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
2863    analogy I have changed it to CFLAGS_FOR_BUILD.
2864    
2865    4. Added -no-undefined to the linking command in the Makefile, because this is
2866    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
2867    linking step for the pcreposix library.
2868    
2869    5. PCRE was failing to diagnose the case of two named groups with the same
2870    name.
2871    
2872    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
2873    literal character that is needed in the subject for a match, and scans along to
2874    ensure that it is present before embarking on the full matching process. This
2875    saves time in cases of nested unlimited repeats that are never going to match.
2876    Problem: the scan can take a lot of time if the subject is very long (e.g.
2877    megabytes), thus penalizing straightforward matches. It is now done only if the
2878    amount of subject to be scanned is less than 1000 bytes.
2879    
2880    7. A lesser problem with the same optimization is that it was recording the
2881    first character of an anchored pattern as "needed", thus provoking a search
2882    right along the subject, even when the first match of the pattern was going to
2883    fail. The "needed" character is now not set for anchored patterns, unless it
2884    follows something in the pattern that is of non-fixed length. Thus, it still
2885    fulfils its original purpose of finding quick non-matches in cases of nested
2886    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
2887    
2888    
2889    Version 4.0 17-Feb-03
2890    ---------------------
2891    
2892    1. If a comment in an extended regex that started immediately after a meta-item
2893    extended to the end of string, PCRE compiled incorrect data. This could lead to
2894    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
2895    
2896    2. Moved to autoconf 2.53 and libtool 1.4.2.
2897    
2898    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
2899    the special perltest8 script is no longer needed - all the tests can be run
2900    from a single perltest script.
2901    
2902    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
2903    by \s. It has now been removed in PCRE. This means it isn't recognized as
2904    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
2905    class [:space:] *does* include VT, thereby creating a mess.
2906    
2907    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
2908    space and tab.
2909    
2910    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
2911    its new features into the main test script, reducing the number of scripts.
2912    
2913    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
2914    were backward compatible, and made the (?i) apply to the whole pattern, as if
2915    /i were given. Now it behaves more logically, and applies the option setting
2916    only to what follows. PCRE has been changed to follow suit. However, if it
2917    finds options settings right at the start of the pattern, it extracts them into
2918    the global options, as before. Thus, they show up in the info data.
2919    
2920    8. Added support for the \Q...\E escape sequence. Characters in between are
2921    treated as literals. This is slightly different from Perl in that $ and @ are
2922    also handled as literals inside the quotes. In Perl, they will cause variable
2923    interpolation. Note the following examples:
2924    
2925        Pattern            PCRE matches      Perl matches
2926    
2927        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
2928        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
2929        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
2930    
2931    For compatibility with Perl, \Q...\E sequences are recognized inside character
2932    classes as well as outside them.
2933    
2934    9. Re-organized 3 code statements in pcretest to avoid "overflow in
2935    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
2936    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
2937    signed/unsigned warnings.
2938    
2939    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
2940    option for pcretest, so I've replaced it by a simple function that does just
2941    that job.
2942    
2943    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
2944    "pcregrep -".
2945    
2946    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
2947    Java package. This provides some syntactic sugar for simple cases of what my
2948    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
2949    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
2950    item, you can use this simplified notation. Note that only makes sense with
2951    greedy quantifiers. Consequently, the use of the possessive quantifier forces
2952    greediness, whatever the setting of the PCRE_UNGREEDY option.
2953    
2954    13. A change of greediness default within a pattern was not taking effect at
2955    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
2956    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
2957    was abstracted outside.
2958    
2959    14. PCRE now supports the \G assertion. It is true when the current matching
2960    position is at the start point of the match. This differs from \A when the
2961    starting offset is non-zero. Used with the /g option of pcretest (or similar
2962    code), it works in the same way as it does for Perl's /g option. If all
2963    alternatives of a regex begin with \G, the expression is anchored to the start
2964    match position, and the "anchored" flag is set in the compiled expression.
2965    
2966    15. Some bugs concerning the handling of certain option changes within patterns
2967    have been fixed. These applied to options other than (?ims). For example,
2968    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
2969    been the other way round. Some of this was related to change 7 above.
2970    
2971    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
2972    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
2973    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
2974    POSIX classes only within a class (e.g. /[[:alpha:]]/).
2975    
2976    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
2977    mode. Unlike ".", it always matches newline, whatever the setting of
2978    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
2979    assertions. Perl allows it, but it doesn't (in general) work because it can't
2980    calculate the length of the lookbehind. At least, that's the case for Perl
2981    5.8.0 - I've been told they are going to document that it doesn't work in
2982    future.
2983    
2984    18. Added an error diagnosis for escapes that PCRE does not support: these are
2985    \L, \l, \N, \P, \p, \U, \u, and \X.
2986    
2987    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
2988    reading past the end of the pattern in cases such as /[abcd/.
2989    
2990    20. PCRE was getting more memory than necessary for patterns with classes that
2991    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
2992    
2993    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
2994    compiling PCRE for use with Virtual Pascal.
2995    
2996    22. Small fix to the Makefile to make it work properly if the build is done
2997    outside the source tree.
2998    
2999    23. Added a new extension: a condition to go with recursion. If a conditional
3000    subpattern starts with (?(R) the "true" branch is used if recursion has
3001    happened, whereas the "false" branch is used only at the top level.
3002    
3003    24. When there was a very long string of literal characters (over 255 bytes
3004    without UTF support, over 250 bytes with UTF support), the computation of how
3005    much memory was required could be incorrect, leading to segfaults or other
3006    strange effects.
3007    
3008    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
3009    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
3010    there was a subsequent back reference to those brackets. This meant that, for
3011    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
3012    possible to check for precisely this case. All we can do is abandon the
3013    optimization if .* occurs inside capturing brackets when there are any back
3014    references whatsoever. (See below for a better fix that came later.)
3015    
3016    26. The handling of the optimization for finding the first character of a
3017    non-anchored pattern, and for finding a character that is required later in the
3018    match were failing in some cases. This didn't break the matching; it just
3019    failed to optimize when it could. The way this is done has been re-implemented.
3020    
3021    27. Fixed typo in error message for invalid (?R item (it said "(?p").
3022    
3023    28. Added a new feature that provides some of the functionality that Perl
3024    provides with (?{...}). The facility is termed a "callout". The way it is done
3025    in PCRE is for the caller to provide an optional function, by setting
3026    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
3027    global variable. By default it is unset, which disables all calling out. To get
3028    the function called, the regex must include (?C) at appropriate points. This
3029    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
3030    This provides a means of identifying different callout points. When PCRE
3031    reaches such a point in the regex, if pcre_callout has been set, the external
3032    function is called. It is provided with data in a structure called
3033    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
3034    matching continues; if it returns a non-zero value, the match at the current
3035    point fails. However, backtracking will occur if possible. [This was changed
3036    later and other features added - see item 49 below.]
3037    
3038    29. pcretest is upgraded to test the callout functionality. It provides a
3039    callout function that displays information. By default, it shows the start of
3040    the match and the current position in the text. There are some new data escapes
3041    to vary what happens:
3042    
3043        \C+         in addition, show current contents of captured substrings
3044        \C-         do not supply a callout function
3045        \C!n        return 1 when callout number n is reached
3046        \C!n!m      return 1 when callout number n is reached for the mth time
3047    
3048    30. If pcregrep was called with the -l option and just a single file name, it
3049    output "<stdin>" if a match was found, instead of the file name.
3050    
3051    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
3052    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
3053    pcre_exec(). This saves a malloc/free per call. The default value of
3054    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
3055    when configuring.
3056    
3057    32. The default maximum size of a compiled pattern is 64K. There have been a
3058    few cases of people hitting this limit. The code now uses macros to handle the
3059    storing of links as offsets within the compiled pattern. It defaults to 2-byte
3060    links, but this can be changed to 3 or 4 bytes by --with-link-size when
3061    configuring. Tests 2 and 5 work only with 2-byte links because they output
3062    debugging information about compiled patterns.
3063    
3064    33. Internal code re-arrangements:
3065    
3066    (a) Moved the debugging function for printing out a compiled regex into
3067        its own source file (printint.c) and used #include to pull it into
3068        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
3069        separate copies.
3070    
3071    (b) Defined the list of op-code names for debugging as a macro in
3072        internal.h so that it is next to the definition of the opcodes.
3073    
3074    (c) Defined a table of op-code lengths for simpler skipping along compiled
3075        code. This is again a macro in internal.h so that it is next to the
3076        definition of the opcodes.
3077    
3078    34. Added support for recursive calls to individual subpatterns, along the
3079    lines of Robin Houston's patch (but implemented somewhat differently).
3080    
3081    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
3082    allow it to read and process whole directories in Win32. This code was
3083    contributed by Lionel Fourquaux; it has not been tested by me.
3084    
3085    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
3086    used to name a group. Names consist of alphanumerics and underscores, and must
3087    be unique. Back references use the syntax (?P=name) and recursive calls use
3088    (?P>name) which is a PCRE extension to the Python extension. Groups still have
3089    numbers. The function pcre_fullinfo() can be used after compilation to extract
3090    a name/number map. There are three relevant calls:
3091    
3092      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
3093      PCRE_INFO_NAMECOUNT            yields the number of entries
3094      PCRE_INFO_NAMETABLE            yields a pointer to the map.
3095    
3096    The map is a vector of fixed-size entries. The size of each entry depends on
3097    the length of the longest name used. The first two bytes of each entry are the
3098    group number, most significant byte first. There follows the corresponding
3099    name, zero terminated. The names are in alphabetical order.
3100    
3101    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
3102    case instead of 255. Making it the same both with and without UTF-8 support
3103    means that the same test output works with both.
3104    
3105    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
3106    calling malloc() with a zero argument.
3107    
3108    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
3109    optimization. I've improved things by keeping a bitmap of backreferences with
3110    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
3111    fact referenced, the optimization can be applied. It is unlikely that a
3112    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
3113    the match to follow \n) will appear inside brackets with a number greater than
3114    31, but if it does, any back reference > 31 suppresses the optimization.
3115    
3116    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
3117    of disabling numbered capturing parentheses. Any opening parenthesis that is
3118    not followed by ? behaves as if it were followed by ?: but named parentheses
3119    can still be used for capturing (and they will acquire numbers in the usual
3120    way).
3121    
3122    41. Redesigned the return codes from the match() function into yes/no/error so
3123    that errors can be passed back from deep inside the nested calls. A malloc
3124    failure while inside a recursive subpattern call now causes the
3125    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
3126    
3127    42. It is now possible to set a limit on the number of times the match()
3128    function is called in a call to pcre_exec(). This facility makes it possible to
3129    limit the amount of recursion and backtracking, though not in a directly
3130    obvious way, because the match() function is used in a number of different
3131    circumstances. The count starts from zero for each position in the subject
3132    string (for non-anchored patterns). The default limit is, for compatibility, a
3133    large number, namely 10 000 000. You can change this in two ways:
3134    
3135    (a) When configuring PCRE before making, you can use --with-match-limit=n
3136        to set a default value for the compiled library.
3137    
3138    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
3139        a different value is set. See 45 below.
3140    
3141    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
3142    
3143    43. Added a new function pcre_config(int, void *) to enable run-time extraction
3144    of things that can be changed at compile time. The first argument specifies
3145    what is wanted and the second points to where the information is to be placed.
3146    The current list of available information is:
3147    
3148      PCRE_CONFIG_UTF8
3149    
3150    The output is an integer that is set to one if UTF-8 support is available;
3151    otherwise it is set to zero.
3152    
3153      PCRE_CONFIG_NEWLINE
3154    
3155    The output is an integer that it set to the value of the code that is used for
3156    newline. It is either LF (10) or CR (13).
3157    
3158      PCRE_CONFIG_LINK_SIZE
3159    
3160    The output is an integer that contains the number of bytes used for internal
3161    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
3162    
3163      PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
3164    
3165    The output is an integer that contains the threshold above which the POSIX
3166    interface uses malloc() for output vectors. See item 31 above.
3167    
3168      PCRE_CONFIG_MATCH_LIMIT
3169    
3170    The output is an unsigned integer that contains the default limit of the number
3171    of match() calls in a pcre_exec() execution. See 42 above.
3172    
3173    44. pcretest has been upgraded by the addition of the -C option. This causes it
3174    to extract all the available output from the new pcre_config() function, and to
3175    output it. The program then exits immediately.
3176    
3177    45. A need has arisen to pass over additional data with calls to pcre_exec() in
3178    order to support additional features. One way would have been to define
3179    pcre_exec2() (for example) with extra arguments, but this would not have been
3180    extensible, and would also have required all calls to the original function to
3181    be mapped to the new one. Instead, I have chosen to extend the mechanism that
3182    is used for passing in "extra" data from pcre_study().
3183    
3184    The pcre_extra structure is now exposed and defined in pcre.h. It currently
3185    contains the following fields:
3186    
3187      flags         a bitmap indicating which of the following fields are set
3188      study_data    opaque data from pcre_study()
3189      match_limit   a way of specifying a limit on match() calls for a specific
3190                      call to pcre_exec()
3191      callout_data  data for callouts (see 49 below)
3192    
3193    The flag bits are also defined in pcre.h, and are
3194    
3195      PCRE_EXTRA_STUDY_DATA
3196      PCRE_EXTRA_MATCH_LIMIT
3197      PCRE_EXTRA_CALLOUT_DATA
3198    
3199    The pcre_study() function now returns one of these new pcre_extra blocks, with
3200    the actual study data pointed to by the study_data field, and the
3201    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
3202    before. That is, this change is entirely upwards-compatible and requires no
3203    change to existing code.
3204    
3205    If you want to pass in additional data to pcre_exec(), you can either place it
3206    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
3207    block.
3208    
3209    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
3210    data string contains the escape sequence \M, pcretest calls pcre_exec() several
3211    times with different match limits, until it finds the minimum value needed for
3212    pcre_exec() to complete. The value is then output. This can be instructive; for
3213    most simple matches the number is quite small, but for pathological cases it
3214    gets very large very quickly.
3215    
3216    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
3217    returns the size of the data block pointed to by the study_data field in a
3218    pcre_extra block, that is, the value that was passed as the argument to
3219    pcre_malloc() when PCRE was getting memory in which to place the information
3220    created by pcre_study(). The fourth argument should point to a size_t variable.
3221    pcretest has been extended so that this information is shown after a successful
3222    pcre_study() call when information about the compiled regex is being displayed.
3223    
3224    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
3225    because what follows is always an absolute path. (Later: it turns out that this
3226    is more than cosmetic for MinGW, because it doesn't like empty path
3227    components.)
3228    
3229    49. Some changes have been made to the callout feature (see 28 above):
3230    
3231    (i)  A callout function now has three choices for what it returns:
3232    
3233           0  =>  success, carry on matching
3234         > 0  =>  failure at this point, but backtrack if possible
3235         < 0  =>  serious error, return this value from pcre_exec()
3236    
3237         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
3238         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
3239         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
3240         use by callout functions. It will never be used by PCRE itself.
3241    
3242    (ii) The pcre_extra structure (see 45 above) has a void * field called
3243         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
3244         pcre_callout_block structure has a field of the same name. The contents of
3245         the field passed in the pcre_extra structure are passed to the callout
3246         function in the corresponding field in the callout block. This makes it
3247         easier to use the same callout-containing regex from multiple threads. For
3248         testing, the pcretest program has a new data escape
3249    
3250           \C*n        pass the number n (may be negative) as callout_data
3251    
3252         If the callout function in pcretest receives a non-zero value as
3253         callout_data, it returns that value.
3254    
3255    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
3256    there were some redundant $(CFLAGS) in commands that are now specified as
3257    $(LINK), which already includes $(CFLAGS).
3258    
3259    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
3260    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
3261    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
3262    one-byte characters throughout. Note that case-insensitive matching applies
3263    only to characters whose values are less than 256. PCRE doesn't support the
3264    notion of cases for higher-valued characters.
3265    
3266    (i)   A character class whose characters are all within 0-255 is handled as
3267          a bit map, and the map is inverted for negative classes. Previously, a
3268          character > 255 always failed to match such a class; however it should
3269          match if the class was a negative one (e.g. [^ab]). This has been fixed.
3270    
3271    (ii)  A negated character class with a single character < 255 is coded as
3272          "not this character" (OP_NOT). This wasn't working properly when the test
3273          character was multibyte, either singly or repeated.
3274    
3275    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
3276          mode, for example: \x{100}{2,3}.
3277    
3278    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
3279          singly or repeated) now correctly test multibyte characters. However,
3280          PCRE doesn't recognize any characters with values greater than 255 as
3281          digits, spaces, or word characters. Such characters always match \D, \S,
3282          and \W, and never match \d, \s, or \w.
3283    
3284    (v)   Classes may now contain characters and character ranges with values
3285          greater than 255. For example: [ab\x{100}-\x{400}].
3286    
3287    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
3288          PCRE in UTF-8 mode.
3289    
3290    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
3291    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
3292    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
3293    value.)
3294    
3295    53. The single man page has become too large. I have therefore split it up into
3296    a number of separate man pages. These also give rise to individual HTML pages;
3297    these are now put in a separate directory, and there is an index.html page that
3298    lists them all. Some hyperlinking between the pages has been installed.
3299    
3300    54. Added convenience functions for handling named capturing parentheses.
3301    
3302    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
3303    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
3304    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
3305    are faulted.
3306    
3307    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
3308    calling configure. These values are used when compiling the dftables.c program
3309    which is run to generate the source of the default character tables. They
3310    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
3311    you will need to set these values.
3312    
3313    57. Updated the building process for Windows DLL, as provided by Fred Cox.
3314    
3315    
3316    Version 3.9 02-Jan-02
3317    ---------------------
3318    
3319    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
3320    
3321    2. If --disable-static was given, the building process failed when trying to
3322    build pcretest and pcregrep. (For some reason it was using libtool to compile
3323    them, which is not right, as they aren't part of the library.)
3324    
3325    
3326    Version 3.8 18-Dec-01
3327    ---------------------
3328    
3329    1. The experimental UTF-8 code was completely screwed up. It was packing the
3330    bytes in the wrong order. How dumb can you get?
3331    
3332    
3333    Version 3.7 29-Oct-01
3334    ---------------------
3335    
3336    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
3337    This caused pcretest, when used on the test data, to segfault. Unfortunately,
3338    this didn't happen under Solaris 8, where I normally test things.
3339    
3340    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
3341    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
3342    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
3343    this fix an hour or so after the initial 3.7 release.)
3344    
3345    
3346    Version 3.6 23-Oct-01
3347    ---------------------
3348    
3349    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
3350    offsets passed as NULL with zero offset count.
3351    
3352    2. The config.guess and config.sub files had not been updated when I moved to
3353    the latest autoconf.
3354    
3355    
3356    Version 3.5 15-Aug-01
3357    ---------------------
3358    
3359    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
3360    had been forgotten.
3361    
3362    2. By using declared but undefined structures, we can avoid using "void"
3363    definitions in pcre.h while keeping the internal definitions of the structures
3364    private.
3365    
3366    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
3367    user point of view, this means that both static and shared libraries are built
3368    by default, but this can be individually controlled. More of the work of
3369    handling this static/shared cases is now inside libtool instead of PCRE's make
3370    file.
3371    
3372    4. The pcretest utility is now installed along with pcregrep because it is
3373    useful for users (to test regexs) and by doing this, it automatically gets
3374    relinked by libtool. The documentation has been turned into a man page, so
3375    there are now .1, .txt, and .html versions in /doc.
3376    
3377    5. Upgrades to pcregrep:
3378       (i)   Added long-form option names like gnu grep.
3379       (ii)  Added --help to list all options with an explanatory phrase.
3380       (iii) Added -r, --recursive to recurse into sub-directories.
3381       (iv)  Added -f, --file to read patterns from a file.
3382    
3383    6. pcre_exec() was referring to its "code" argument before testing that
3384    argument for NULL (and giving an error if it was NULL).
3385    
3386    7. Upgraded Makefile.in to allow for compiling in a different directory from
3387    the source directory.
3388    
3389    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
3390    options bits, the pointer it was passed was to an int instead of to an unsigned
3391    long int. This mattered only on 64-bit systems.
3392    
3393    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
3394    generated) instead of pcre.in, which it its source. Also made the same change
3395    in several of the .c files.
3396    
3397    10. A new release of gcc defines printf() as a macro, which broke pcretest
3398    because it had an ifdef in the middle of a string argument for printf(). Fixed
3399    by using separate calls to printf().
3400    
3401    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
3402    script, to force use of CR or LF instead of \n in the source. On non-Unix
3403    systems, the value can be set in config.h.
3404    
3405    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
3406    absolute limit. Changed the text of the error message to make this clear, and
3407    likewise updated the man page.
3408    
3409    13. The limit of 99 on the number of capturing subpatterns has been removed.
3410    The new limit is 65535, which I hope will not be a "real" limit.
3411    
3412    
3413    Version 3.4 22-Aug-00
3414    ---------------------
3415    
3416    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
3417    
3418    2. Diagnose condition (?(0) as an error instead of crashing on matching.
3419    
3420    
3421    Version 3.3 01-Aug-00
3422    ---------------------
3423    
3424    1. If an octal character was given, but the value was greater than \377, it
3425    was not getting masked to the least significant bits, as documented. This could
3426    lead to crashes in some systems.
3427    
3428    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
3429    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
3430    
3431    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
3432    These just pass their arguments on to (pcre_free)(), but they are provided
3433    because some uses of PCRE bind it to non-C systems that can call its functions,
3434    but cannot call free() or pcre_free() directly.
3435    
3436    4. Add "make test" as a synonym for "make check". Corrected some comments in
3437    the Makefile.
3438    
3439    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
3440    Makefile.
3441    
3442    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
3443    command called pgrep for grepping around the active processes.
3444    
3445    7. Added the beginnings of support for UTF-8 character strings.
3446    
3447    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
3448    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
3449    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
3450    out for the ar command.)
3451    
3452    
3453    Version 3.2 12-May-00
3454    ---------------------
3455    
3456    This is purely a bug fixing release.
3457    
3458    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
3459    of ZA. This was just one example of several cases that could provoke this bug,
3460    which was introduced by change 9 of version 2.00. The code for breaking
3461    infinite loops after an iteration that matches an empty string was't working
3462    correctly.
3463    
3464    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
3465    when matched against abbab (for example). After matching an empty string, it
3466    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
3467    caused it to match further down the string than it should.
3468    
3469    3. The code contained an inclusion of sys/types.h. It isn't clear why this
3470    was there because it doesn't seem to be needed, and it causes trouble on some
3471    systems, as it is not a Standard C header. It has been removed.
3472    
3473    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
3474    were reported on the Macintosh. The changes were from
3475    
3476      while ((c = *(++ptr)) != 0 && c != '\n');
3477    to
3478      while ((c = *(++ptr)) != 0 && c != '\n') ;
3479    
3480    Totally extraordinary, but if that's what it takes...
3481    
3482    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
3483    available. Added HAVE_BCOPY and an autoconf test for it; if neither
3484    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
3485    assumes the way PCRE uses memmove() (always moving upwards).
3486    
3487    6. PCRE is being used in one environment where strchr() is not available. There
3488    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
3489    faster code anyway.
3490    
3491    
3492  Version 3.1 09-Feb-00  Version 3.1 09-Feb-00
3493  ---------------------  ---------------------

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