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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 7.4 10-Sep-07
5    ---------------------
6    
7    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
8        means that a class such as [\s] counted as "explicit reference to CR or
9        LF". That isn't really right - the whole point of the change was to try to
10        help when there was an actual mention of one of the two characters. So now
11        the change happens only if \r or \n (or a literal CR or LF) character is
12        encountered.
13    
14    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
15        of both had grown to the point where there were only 3 bits left.
16        Fortunately, there was spare space in the data structure, and so I have
17        moved the internal flags into a new 16-bit field to free up more option
18        bits.
19    
20    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
21        but did not set the internal JCHANGED flag - either of these is enough to
22        control the way the "get" function works - but the PCRE_INFO_JCHANGED
23        facility is supposed to tell if (?J) was ever used, so now (?J) at the
24        start sets both bits.
25    
26    4.  Added options (at build time, compile time, exec time) to change \R from
27        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
28    
29    5.  doc/pcresyntax.html was missing from the distribution.
30    
31    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
32        compatibility, even though it is no longer used.
33    
34    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
35        strtoull to pcrecpp.cc to select the available functions in WIN32 (where
36        different names are used).
37    
38    8.  Changed all #include <config.h> to #include "config.h". There were also
39        some further <pcre.h> cases that I changed to "pcre.h".
40    
41    9.  When pcregrep was used with the --colour option, it missed the line ending
42        sequence off the lines that it output.
43    
44    10. It was pointed out to me that arrays of string pointers cause lots of
45        relocations when a shared library is dynamically loaded. A technique of
46        using a single long string with a table of offsets can drastically reduce
47        these. I have refactored PCRE in four places to do this. The result is
48        dramatic:
49    
50          Originally:                          290
51          After changing UCP table:            187
52          After changing error message table:   43
53          After changing table of "verbs"       36
54          After changing table of Posix names   22
55    
56        Thanks to the folks working on Gregex for glib for this insight.
57    
58    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
59        unicode-properties was also set.
60    
61    12. Updated the RunTest script to miss out tests that don't work if \R is
62        defaulted to ANYCRLF.
63    
64    
65    Version 7.3 28-Aug-07
66    ---------------------
67    
68     1. In the rejigging of the build system that eventually resulted in 7.1, the
69        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
70        brackets there is not right, since it causes compilers to look for an
71        installed pcre.h, not the version that is in the source that is being
72        compiled (which of course may be different). I have changed it back to:
73    
74          #include "pcre.h"
75    
76        I have a vague recollection that the change was concerned with compiling in
77        different directories, but in the new build system, that is taken care of
78        by the VPATH setting the Makefile.
79    
80     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
81        when the subject happened to end in the byte 0x85 (e.g. if the last
82        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
83        characters but of course it shouldn't be taken as a newline when it is part
84        of another character. The bug was that, for an unlimited repeat of . in
85        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
86        characters when looking for a newline.
87    
88     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
89    
90     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
91        in debug output.
92    
93     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
94        long printing in the pcrecpp unittest when running under MinGW.
95    
96     6. ESC_K was left out of the EBCDIC table.
97    
98     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
99        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
100        limit also applies to "virtual nesting" when a pattern is recursive, and in
101        this case 1000 isn't so big. I have been able to remove this limit at the
102        expense of backing off one optimization in certain circumstances. Normally,
103        when pcre_exec() would call its internal match() function recursively and
104        immediately return the result unconditionally, it uses a "tail recursion"
105        feature to save stack. However, when a subpattern that can match an empty
106        string has an unlimited repetition quantifier, it no longer makes this
107        optimization. That gives it a stack frame in which to save the data for
108        checking that an empty string has been matched. Previously this was taken
109        from the 1000-entry workspace that had been reserved. So now there is no
110        explicit limit, but more stack is used.
111    
112     8. Applied Daniel's patches to solve problems with the import/export magic
113        syntax that is required for Windows, and which was going wrong for the
114        pcreposix and pcrecpp parts of the library. These were overlooked when this
115        problem was solved for the main library.
116    
117     9. There were some crude static tests to avoid integer overflow when computing
118        the size of patterns that contain repeated groups with explicit upper
119        limits. As the maximum quantifier is 65535, the maximum group length was
120        set at 30,000 so that the product of these two numbers did not overflow a
121        32-bit integer. However, it turns out that people want to use groups that
122        are longer than 30,000 bytes (though not repeat them that many times).
123        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
124        made it possible to implement the integer overflow checks in a much more
125        dynamic way, which I have now done. The artificial limitation on group
126        length has been removed - we now have only the limit on the total length of
127        the compiled pattern, which depends on the LINK_SIZE setting.
128    
129    10. Fixed a bug in the documentation for get/copy named substring when
130        duplicate names are permitted. If none of the named substrings are set, the
131        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
132        empty string.
133    
134    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
135        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
136        because the ] is interpreted as the first data character and the
137        terminating ] is not found. PCRE has been made compatible with Perl in this
138        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
139        cause memory overwriting.
140    
141    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
142        string has been matched (to stop an infinite loop). It was not recognizing
143        a conditional subpattern that could match an empty string if that
144        subpattern was within another subpattern. For example, it looped when
145        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
146        condition was not nested. This bug has been fixed.
147    
148    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
149        past the start of the subject in the presence of bytes with the top bit
150        set, for example "\x8aBCD".
151    
152    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
153        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
154    
155    14. Optimized (?!) to (*FAIL).
156    
157    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
158        This restricts code points to be within the range 0 to 0x10FFFF, excluding
159        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
160        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
161        does: it's just the validity check that is more restrictive.
162    
163    16. Inserted checks for integer overflows during escape sequence (backslash)
164        processing, and also fixed erroneous offset values for syntax errors during
165        backslash processing.
166    
167    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
168        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
169    
170    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
171        caused an overrun.
172    
173    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
174        something other than just ASCII characters) inside a group that had an
175        unlimited repeat caused a loop at compile time (while checking to see
176        whether the group could match an empty string).
177    
178    20. Debugging a pattern containing \p or \P could cause a crash. For example,
179        [\P{Any}] did so. (Error in the code for printing property names.)
180    
181    21. An orphan \E inside a character class could cause a crash.
182    
183    22. A repeated capturing bracket such as (A)? could cause a wild memory
184        reference during compilation.
185    
186    23. There are several functions in pcre_compile() that scan along a compiled
187        expression for various reasons (e.g. to see if it's fixed length for look
188        behind). There were bugs in these functions when a repeated \p or \P was
189        present in the pattern. These operators have additional parameters compared
190        with \d, etc, and these were not being taken into account when moving along
191        the compiled data. Specifically:
192    
193        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
194            length.
195    
196        (b) An item such as \pL+ within a repeated group could cause crashes or
197            loops.
198    
199        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
200            "reference to non-existent subpattern" error.
201    
202        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
203    
204    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
205        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
206    
207    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
208    
209    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
210        character were causing crashes (broken optimization).
211    
212    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
213        \p or \P) caused a compile-time loop.
214    
215    28. More problems have arisen in unanchored patterns when CRLF is a valid line
216        break. For example, the unstudied pattern [\r\n]A does not match the string
217        "\r\nA" because change 7.0/46 below moves the current point on by two
218        characters after failing to match at the start. However, the pattern \nA
219        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
220        the same is true. There doesn't seem any very clean way out of this, but
221        what I have chosen to do makes the common cases work: PCRE now takes note
222        of whether there can be an explicit match for \r or \n anywhere in the
223        pattern, and if so, 7.0/46 no longer applies. As part of this change,
224        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
225        pattern has explicit CR or LF references.
226    
227    29. Added (*CR) etc for changing newline setting at start of pattern.
228    
229    
230    Version 7.2 19-Jun-07
231    ---------------------
232    
233     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
234        which is apparently normally available under Windows.
235    
236     2. Re-jig the pcregrep tests with different newline settings in an attempt
237        to make them independent of the local environment's newline setting.
238    
239     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
240    
241     4. Some of the "internals" tests were previously cut out when the link size
242        was not 2, because the output contained actual offsets. The recent new
243        "Z" feature of pcretest means that these can be cut out, making the tests
244        usable with all link sizes.
245    
246     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
247        stack recursion. This gives a massive performance boost under BSD, but just
248        a small improvement under Linux. However, it saves one field in the frame
249        in all cases.
250    
251     6. Added more features from the forthcoming Perl 5.10:
252    
253        (a) (?-n) (where n is a string of digits) is a relative subroutine or
254            recursion call. It refers to the nth most recently opened parentheses.
255    
256        (b) (?+n) is also a relative subroutine call; it refers to the nth next
257            to be opened parentheses.
258    
259        (c) Conditions that refer to capturing parentheses can be specified
260            relatively, for example, (?(-2)... or (?(+3)...
261    
262        (d) \K resets the start of the current match so that everything before
263            is not part of it.
264    
265        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
266    
267        (f) \g{name} is another synonym - part of Perl 5.10's unification of
268            reference syntax.
269    
270        (g) (?| introduces a group in which the numbering of parentheses in each
271            alternative starts with the same number.
272    
273        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
274    
275     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
276        PCRE_INFO_JCHANGED.
277    
278     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
279        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
280        for detecting groups that can match an empty string.
281    
282     9. A pattern with a very large number of alternatives (more than several
283        hundred) was running out of internal workspace during the pre-compile
284        phase, where pcre_compile() figures out how much memory will be needed. A
285        bit of new cunning has reduced the workspace needed for groups with
286        alternatives. The 1000-alternative test pattern now uses 12 bytes of
287        workspace instead of running out of the 4096 that are available.
288    
289    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
290    
291    11. Applied patch from Google to remove an optimization that didn't quite work.
292        The report of the bug said:
293    
294          pcrecpp::RE("a*").FullMatch("aaa") matches, while
295          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
296          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
297    
298    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
299        it matched the wrong number of bytes.
300    
301    
302    Version 7.1 24-Apr-07
303    ---------------------
304    
305     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
306        that is more "standard", making use of automake and other Autotools. There
307        is some re-arrangement of the files and adjustment of comments consequent
308        on this.
309    
310     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
311        for recursive directory scanning broke on some systems because the files
312        are not scanned in any specific order and on different systems the order
313        was different. A call to "sort" has been inserted into RunGrepTest for the
314        approprate test as a short-term fix. In the longer term there may be an
315        alternative.
316    
317     3. I had an email from Eric Raymond about problems translating some of PCRE's
318        man pages to HTML (despite the fact that I distribute HTML pages, some
319        people do their own conversions for various reasons). The problems
320        concerned the use of low-level troff macros .br and .in. I have therefore
321        removed all such uses from the man pages (some were redundant, some could
322        be replaced by .nf/.fi pairs). The 132html script that I use to generate
323        HTML has been updated to handle .nf/.fi and to complain if it encounters
324        .br or .in.
325    
326     4. Updated comments in configure.ac that get placed in config.h.in and also
327        arranged for config.h to be included in the distribution, with the name
328        config.h.generic, for the benefit of those who have to compile without
329        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
330    
331     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
332        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
333        makevp.bat for the current PCRE, using the additional files
334        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
335    
336     6. A Windows user reported a minor discrepancy with test 2, which turned out
337        to be caused by a trailing space on an input line that had got lost in his
338        copy. The trailing space was an accident, so I've just removed it.
339    
340     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
341        that is needed.
342    
343     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
344        as "const" (a) because they are and (b) because it helps the PHP
345        maintainers who have recently made a script to detect big data structures
346        in the php code that should be moved to the .rodata section. I remembered
347        to update Builducptable as well, so it won't revert if ucptable.h is ever
348        re-created.
349    
350     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
351        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
352        order to be able to cut out the UTF-8 tables in the latter when UTF-8
353        support is not required. This saves 1.5-2K of code, which is important in
354        some applications.
355    
356        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
357        so as not to refer to the tables, even though these functions will never be
358        called when UTF-8 support is disabled. Otherwise there are problems with a
359        shared library.
360    
361    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
362    
363        (a) It was defining its arguments as char * instead of void *.
364    
365        (b) It was assuming that all moves were upwards in memory; this was true
366            a long time ago when I wrote it, but is no longer the case.
367    
368        The emulated memove() is provided for those environments that have neither
369        memmove() nor bcopy(). I didn't think anyone used it these days, but that
370        is clearly not the case, as these two bugs were recently reported.
371    
372    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
373        and Detrail to create the HTML documentation, the .txt form of the man
374        pages, and it removes trailing spaces from listed files. It also creates
375        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
376        case, it wraps all the #defines with #ifndefs. This script should be run
377        before "make dist".
378    
379    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
380        with Unicode property support.
381    
382        (a) For a maximizing quantifier, if the two different cases of the
383            character were of different lengths in their UTF-8 codings (there are
384            some cases like this - I found 11), and the matching function had to
385            back up over a mixture of the two cases, it incorrectly assumed they
386            were both the same length.
387    
388        (b) When PCRE was configured to use the heap rather than the stack for
389            recursion during matching, it was not correctly preserving the data for
390            the other case of a UTF-8 character when checking ahead for a match
391            while processing a minimizing repeat. If the check also involved
392            matching a wide character, but failed, corruption could cause an
393            erroneous result when trying to check for a repeat of the original
394            character.
395    
396    13. Some tidying changes to the testing mechanism:
397    
398        (a) The RunTest script now detects the internal link size and whether there
399            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
400            values substituted by "configure". (The RunGrepTest script already did
401            this for UTF-8.) The configure.ac script no longer substitutes the
402            relevant variables.
403    
404        (b) The debugging options /B and /D in pcretest show the compiled bytecode
405            with length and offset values. This means that the output is different
406            for different internal link sizes. Test 2 is skipped for link sizes
407            other than 2 because of this, bypassing the problem. Unfortunately,
408            there was also a test in test 3 (the locale tests) that used /B and
409            failed for link sizes other than 2. Rather than cut the whole test out,
410            I have added a new /Z option to pcretest that replaces the length and
411            offset values with spaces. This is now used to make test 3 independent
412            of link size. (Test 2 will be tidied up later.)
413    
414    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
415        segmentation fault instead of returning the appropriate error message.
416    
417    15. In multiline mode when the newline sequence was set to "any", the pattern
418        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
419        This doesn't seem right; it now treats the CRLF combination as the line
420        ending, and so does not match in that case. It's only a pattern such as ^$
421        that would hit this one: something like ^ABC$ would have failed after \r
422        and then tried again after \r\n.
423    
424    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
425        in an attempt to make files that differ only in their line terminators
426        compare equal. This works on Linux.
427    
428    17. Under certain error circumstances pcregrep might try to free random memory
429        as it exited. This is now fixed, thanks to valgrind.
430    
431    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
432        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
433        was because its rules for how to advance for /g after matching an empty
434        string at the end of a line did not allow for this case. They now check for
435        it specially.
436    
437    20. pcretest is supposed to handle patterns and data of any length, by
438        extending its buffers when necessary. It was getting this wrong when the
439        buffer for a data line had to be extended.
440    
441    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
442        CRLF as a newline sequence.
443    
444    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
445        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
446        I have nevertheless tidied it up.
447    
448    23. Added some casts to kill warnings from HP-UX ia64 compiler.
449    
450    24. Added a man page for pcre-config.
451    
452    
453    Version 7.0 19-Dec-06
454    ---------------------
455    
456     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
457        moving to gcc 4.1.1.
458    
459     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
460        sys/time.h, which is documented as needed for this function. It doesn't
461        seem to matter on Linux, but it showed up on some releases of OS X.
462    
463     3. It seems that there are systems where bytes whose values are greater than
464        127 match isprint() in the "C" locale. The "C" locale should be the
465        default when a C program starts up. In most systems, only ASCII printing
466        characters match isprint(). This difference caused the output from pcretest
467        to vary, making some of the tests fail. I have changed pcretest so that:
468    
469        (a) When it is outputting text in the compiled version of a pattern, bytes
470            other than 32-126 are always shown as hex escapes.
471    
472        (b) When it is outputting text that is a matched part of a subject string,
473            it does the same, unless a different locale has been set for the match
474            (using the /L modifier). In this case, it uses isprint() to decide.
475    
476     4. Fixed a major bug that caused incorrect computation of the amount of memory
477        required for a compiled pattern when options that changed within the
478        pattern affected the logic of the preliminary scan that determines the
479        length. The relevant options are -x, and -i in UTF-8 mode. The result was
480        that the computed length was too small. The symptoms of this bug were
481        either the PCRE error "internal error: code overflow" from pcre_compile(),
482        or a glibc crash with a message such as "pcretest: free(): invalid next
483        size (fast)". Examples of patterns that provoked this bug (shown in
484        pcretest format) are:
485    
486          /(?-x: )/x
487          /(?x)(?-x: \s*#\s*)/
488          /((?i)[\x{c0}])/8
489          /(?i:[\x{c0}])/8
490    
491        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
492        is now done differently.
493    
494     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
495        wrapper classes; (b) implement a new function in the C++ scanner that is
496        more efficient than the old way of doing things because it avoids levels of
497        recursion in the regex matching; (c) add a paragraph to the documentation
498        for the FullMatch() function.
499    
500     6. The escape sequence \n was being treated as whatever was defined as
501        "newline". Not only was this contrary to the documentation, which states
502        that \n is character 10 (hex 0A), but it also went horribly wrong when
503        "newline" was defined as CRLF. This has been fixed.
504    
505     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
506        was being set to -1 for the "end of line" case (supposedly a value that no
507        character can have). Though this value is never used (the check for end of
508        line is "zero bytes in current character"), it caused compiler complaints.
509        I've changed it to 0xffffffff.
510    
511     8. In pcre_version.c, the version string was being built by a sequence of
512        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
513        string (as it is for production releases) called a macro with an empty
514        argument. The C standard says the result of this is undefined. The gcc
515        compiler treats it as an empty string (which was what was wanted) but it is
516        reported that Visual C gives an error. The source has been hacked around to
517        avoid this problem.
518    
519     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
520        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
521        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
522        of them did).
523    
524    10. Originally, pcretest opened its input and output without "b"; then I was
525        told that "b" was needed in some environments, so it was added for release
526        5.0 to both the input and output. (It makes no difference on Unix-like
527        systems.) Later I was told that it is wrong for the input on Windows. I've
528        now abstracted the modes into two macros, to make it easier to fiddle with
529        them, and removed "b" from the input mode under Windows.
530    
531    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
532    
533    12. Added -help and --help to pcretest as an official way of being reminded
534        of the options.
535    
536    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
537        and pcrecpp.cc because they annoy compilers at high warning levels.
538    
539    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
540    
541    15. Fixed an occurrence of == in configure.ac that should have been = (shell
542        scripts are not C programs :-) and which was not noticed because it works
543        on Linux.
544    
545    16. pcretest is supposed to handle any length of pattern and data line (as one
546        line or as a continued sequence of lines) by extending its input buffer if
547        necessary. This feature was broken for very long pattern lines, leading to
548        a string of junk being passed to pcre_compile() if the pattern was longer
549        than about 50K.
550    
551    17. I have done a major re-factoring of the way pcre_compile() computes the
552        amount of memory needed for a compiled pattern. Previously, there was code
553        that made a preliminary scan of the pattern in order to do this. That was
554        OK when PCRE was new, but as the facilities have expanded, it has become
555        harder and harder to keep it in step with the real compile phase, and there
556        have been a number of bugs (see for example, 4 above). I have now found a
557        cunning way of running the real compile function in a "fake" mode that
558        enables it to compute how much memory it would need, while actually only
559        ever using a few hundred bytes of working memory and without too many
560        tests of the mode. This should make future maintenance and development
561        easier. A side effect of this work is that the limit of 200 on the nesting
562        depth of parentheses has been removed (though this was never a serious
563        limitation, I suspect). However, there is a downside: pcre_compile() now
564        runs more slowly than before (30% or more, depending on the pattern). I
565        hope this isn't a big issue. There is no effect on runtime performance.
566    
567    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
568        newline (only possible for the last line of a file) and it was a
569        pattern that set a locale (followed by /Lsomething), pcretest crashed.
570    
571    19. Added additional timing features to pcretest. (1) The -tm option now times
572        matching only, not compiling. (2) Both -t and -tm can be followed, as a
573        separate command line item, by a number that specifies the number of
574        repeats to use when timing. The default is 50000; this gives better
575        precision, but takes uncomfortably long for very large patterns.
576    
577    20. Extended pcre_study() to be more clever in cases where a branch of a
578        subpattern has no definite first character. For example, (a*|b*)[cd] would
579        previously give no result from pcre_study(). Now it recognizes that the
580        first character must be a, b, c, or d.
581    
582    21. There was an incorrect error "recursive call could loop indefinitely" if
583        a subpattern (or the entire pattern) that was being tested for matching an
584        empty string contained only one non-empty item after a nested subpattern.
585        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
586        incorrectly, because the \d was being skipped in the check.
587    
588    22. The pcretest program now has a new pattern option /B and a command line
589        option -b, which is equivalent to adding /B to every pattern. This causes
590        it to show the compiled bytecode, without the additional information that
591        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
592        is the same as /B/I).
593    
594    23. A new optimization is now able automatically to treat some sequences such
595        as a*b as a*+b. More specifically, if something simple (such as a character
596        or a simple class like \d) has an unlimited quantifier, and is followed by
597        something that cannot possibly match the quantified thing, the quantifier
598        is automatically "possessified".
599    
600    24. A recursive reference to a subpattern whose number was greater than 39
601        went wrong under certain circumstances in UTF-8 mode. This bug could also
602        have affected the operation of pcre_study().
603    
604    25. Realized that a little bit of performance could be had by replacing
605        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
606    
607    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
608    
609    27. Possessive quantifiers such as a++ were previously implemented by turning
610        them into atomic groups such as ($>a+). Now they have their own opcodes,
611        which improves performance. This includes the automatically created ones
612        from 23 above.
613    
614    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
615        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
616        the first matched character to be a colon. This applied both to named and
617        numbered groups.
618    
619    29. The ucpinternal.h header file was missing its idempotency #ifdef.
620    
621    30. I was sent a "project" file called libpcre.a.dev which I understand makes
622        building PCRE on Windows easier, so I have included it in the distribution.
623    
624    31. There is now a check in pcretest against a ridiculously large number being
625        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
626        loop, the loop is abandoned.
627    
628    32. Forward references to subpatterns in conditions such as (?(2)...) where
629        subpattern 2 is defined later cause pcre_compile() to search forwards in
630        the pattern for the relevant set of parentheses. This search went wrong
631        when there were unescaped parentheses in a character class, parentheses
632        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
633    
634    33. "Subroutine" calls and backreferences were previously restricted to
635        referencing subpatterns earlier in the regex. This restriction has now
636        been removed.
637    
638    34. Added a number of extra features that are going to be in Perl 5.10. On the
639        whole, these are just syntactic alternatives for features that PCRE had
640        previously implemented using the Python syntax or my own invention. The
641        other formats are all retained for compatibility.
642    
643        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
644            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
645            also .NET compatible.
646    
647        (b) A recursion or subroutine call to a named group can now be defined as
648            (?&name) as well as (?P>name).
649    
650        (c) A backreference to a named group can now be defined as \k<name> or
651            \k'name' as well as (?P=name). The new forms, as well as being in Perl
652            5.10, are also .NET compatible.
653    
654        (d) A conditional reference to a named group can now use the syntax
655            (?(<name>) or (?('name') as well as (?(name).
656    
657        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
658            groups (named and numbered) that are never evaluated inline, but can be
659            called as "subroutines" from elsewhere. In effect, the DEFINE condition
660            is always false. There may be only one alternative in such a group.
661    
662        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
663            as the simple (?(R). The condition is true only if the most recent
664            recursion is that of the given number or name. It does not search out
665            through the entire recursion stack.
666    
667        (g) The escape \gN or \g{N} has been added, where N is a positive or
668            negative number, specifying an absolute or relative reference.
669    
670    35. Tidied to get rid of some further signed/unsigned compiler warnings and
671        some "unreachable code" warnings.
672    
673    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
674        things, this adds five new scripts.
675    
676    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
677        There were also incompatibilities regarding the handling of \Q..\E inside
678        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
679        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
680    
681    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
682        matches an empty string, and forcibly breaks the loop. There were bugs in
683        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
684        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
685        separate and independent bugs (that affected different cases) have been
686        fixed.
687    
688    39. Refactored the code to abolish the use of different opcodes for small
689        capturing bracket numbers. This is a tidy that I avoided doing when I
690        removed the limit on the number of capturing brackets for 3.5 back in 2001.
691        The new approach is not only tidier, it makes it possible to reduce the
692        memory needed to fix the previous bug (38).
693    
694    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
695        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
696        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
697        mode.
698    
699    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
700        report.
701    
702    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
703        copy construction and assignment in the C++ wrapper.
704    
705    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
706        couple of bugs that could have given wrong results in the "--newline=crlf"
707        case.
708    
709    44. Added a number of casts and did some reorganization of signed/unsigned int
710        variables following suggestions from Dair Grant. Also renamed the variable
711        "this" as "item" because it is a C++ keyword.
712    
713    45. Arranged for dftables to add
714    
715          #include "pcre_internal.h"
716    
717        to pcre_chartables.c because without it, gcc 4.x may remove the array
718        definition from the final binary if PCRE is built into a static library and
719        dead code stripping is activated.
720    
721    46. For an unanchored pattern, if a match attempt fails at the start of a
722        newline sequence, and the newline setting is CRLF or ANY, and the next two
723        characters are CRLF, advance by two characters instead of one.
724    
725    
726    Version 6.7 04-Jul-06
727    ---------------------
728    
729     1. In order to handle tests when input lines are enormously long, pcretest has
730        been re-factored so that it automatically extends its buffers when
731        necessary. The code is crude, but this _is_ just a test program. The
732        default size has been increased from 32K to 50K.
733    
734     2. The code in pcre_study() was using the value of the re argument before
735        testing it for NULL. (Of course, in any sensible call of the function, it
736        won't be NULL.)
737    
738     3. The memmove() emulation function in pcre_internal.h, which is used on
739        systems that lack both memmove() and bcopy() - that is, hardly ever -
740        was missing a "static" storage class specifier.
741    
742     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
743        containing an extended class (one that cannot be represented by a bitmap
744        because it contains high-valued characters or Unicode property items, e.g.
745        [\pZ]). Almost always one would set UTF-8 mode when processing such a
746        pattern, but PCRE should not loop if you do not (it no longer does).
747        [Detail: two cases were found: (a) a repeated subpattern containing an
748        extended class; (b) a recursive reference to a subpattern that followed a
749        previous extended class. It wasn't skipping over the extended class
750        correctly when UTF-8 mode was not set.]
751    
752     5. A negated single-character class was not being recognized as fixed-length
753        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
754        compile error "lookbehind assertion is not fixed length".
755    
756     6. The RunPerlTest auxiliary script was showing an unexpected difference
757        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
758        write a Perl script that can interpret lines of an input file either as
759        byte characters or as UTF-8, which is what "perltest" was being required to
760        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
761        can't do is switch easily at run time between having the "use utf8;" pragma
762        or not. In the end, I fudged it by using the RunPerlTest script to insert
763        "use utf8;" explicitly for the UTF-8 tests.
764    
765     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
766        the end of the subject string, contrary to the documentation and to what
767        Perl does. This was true of both matching functions. Now it matches only at
768        the start of the subject and immediately after *internal* newlines.
769    
770     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
771        a pointer to an int instead of a pointer to an unsigned long int. This
772        caused problems on 64-bit systems.
773    
774     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
775        instance of the 'standard' template library not being so standard".
776    
777    10. There was no check on the number of named subpatterns nor the maximum
778        length of a subpattern name. The product of these values is used to compute
779        the size of the memory block for a compiled pattern. By supplying a very
780        long subpattern name and a large number of named subpatterns, the size
781        computation could be caused to overflow. This is now prevented by limiting
782        the length of names to 32 characters, and the number of named subpatterns
783        to 10,000.
784    
785    11. Subpatterns that are repeated with specific counts have to be replicated in
786        the compiled pattern. The size of memory for this was computed from the
787        length of the subpattern and the repeat count. The latter is limited to
788        65535, but there was no limit on the former, meaning that integer overflow
789        could in principle occur. The compiled length of a repeated subpattern is
790        now limited to 30,000 bytes in order to prevent this.
791    
792    12. Added the optional facility to have named substrings with the same name.
793    
794    13. Added the ability to use a named substring as a condition, using the
795        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
796        are numbers (not recommended). Forward references are permitted.
797    
798    14. Added forward references in named backreferences (if you see what I mean).
799    
800    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
801        pattern could run off the end of the subject. For example, the pattern
802        "(?s)(.{1,5})"8 did this with the subject "ab".
803    
804    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
805        PCRE_CASELESS was set when matching characters that were quantified with ?
806        or *.
807    
808    17. A character class other than a single negated character that had a minimum
809        but no maximum quantifier - for example [ab]{6,} - was not handled
810        correctly by pce_dfa_exec(). It would match only one character.
811    
812    18. A valid (though odd) pattern that looked like a POSIX character
813        class but used an invalid character after [ (for example [[,abc,]]) caused
814        pcre_compile() to give the error "Failed: internal error: code overflow" or
815        in some cases to crash with a glibc free() error. This could even happen if
816        the pattern terminated after [[ but there just happened to be a sequence of
817        letters, a binary zero, and a closing ] in the memory that followed.
818    
819    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
820        over the years. Originally (before any Unicode support), just the bottom 8
821        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
822        output from "man perlunicode" includes this:
823    
824          The regular expression compiler produces polymorphic opcodes.  That
825          is, the pattern adapts to the data and automatically switches to
826          the Unicode character scheme when presented with Unicode data--or
827          instead uses a traditional byte scheme when presented with byte
828          data.
829    
830        Sadly, a wide octal escape does not cause a switch, and in a string with
831        no other multibyte characters, these octal escapes are treated as before.
832        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
833        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
834        Unicode string.
835    
836        I have not perpetrated such confusion in PCRE. Up till now, it took just
837        the bottom 8 bits, as in old Perl. I have now made octal escapes with
838        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
839        translate to the appropriate multibyte character.
840    
841    29. Applied some refactoring to reduce the number of warnings from Microsoft
842        and Borland compilers. This has included removing the fudge introduced
843        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
844        a warning about an unused variable.
845    
846    21. PCRE has not included VT (character 0x0b) in the set of whitespace
847        characters since release 4.0, because Perl (from release 5.004) does not.
848        [Or at least, is documented not to: some releases seem to be in conflict
849        with the documentation.] However, when a pattern was studied with
850        pcre_study() and all its branches started with \s, PCRE still included VT
851        as a possible starting character. Of course, this did no harm; it just
852        caused an unnecessary match attempt.
853    
854    22. Removed a now-redundant internal flag bit that recorded the fact that case
855        dependency changed within the pattern. This was once needed for "required
856        byte" processing, but is no longer used. This recovers a now-scarce options
857        bit. Also moved the least significant internal flag bit to the most-
858        significant bit of the word, which was not previously used (hangover from
859        the days when it was an int rather than a uint) to free up another bit for
860        the future.
861    
862    23. Added support for CRLF line endings as well as CR and LF. As well as the
863        default being selectable at build time, it can now be changed at runtime
864        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
865        specify that it is scanning data with non-default line endings.
866    
867    24. Changed the definition of CXXLINK to make it agree with the definition of
868        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
869    
870    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
871        recursions. This makes a big different to stack usage for some patterns.
872    
873    26. If a subpattern containing a named recursion or subroutine reference such
874        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
875        the space required for the compiled pattern went wrong and gave too small a
876        value. Depending on the environment, this could lead to "Failed: internal
877        error: code overflow at offset 49" or "glibc detected double free or
878        corruption" errors.
879    
880    27. Applied patches from Google (a) to support the new newline modes and (b) to
881        advance over multibyte UTF-8 characters in GlobalReplace.
882    
883    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
884        difference for some implementation of PCRE in some Windows version.
885    
886    29. Added some extra testing facilities to pcretest:
887    
888        \q<number>   in a data line sets the "match limit" value
889        \Q<number>   in a data line sets the "match recursion limt" value
890        -S <number>  sets the stack size, where <number> is in megabytes
891    
892        The -S option isn't available for Windows.
893    
894    
895    Version 6.6 06-Feb-06
896    ---------------------
897    
898     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
899        in pcreposix.h. I have copied the definition from pcre.h.
900    
901     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
902        because pcre.h is no longer a built file.
903    
904     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
905        not normally included in the compiled code.
906    
907    
908    Version 6.5 01-Feb-06
909    ---------------------
910    
911     1. When using the partial match feature with pcre_dfa_exec(), it was not
912        anchoring the second and subsequent partial matches at the new starting
913        point. This could lead to incorrect results. For example, with the pattern
914        /1234/, partially matching against "123" and then "a4" gave a match.
915    
916     2. Changes to pcregrep:
917    
918        (a) All non-match returns from pcre_exec() were being treated as failures
919            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
920            error message is output. Some extra information is given for the
921            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
922            probably the only errors that are likely to be caused by users (by
923            specifying a regex that has nested indefinite repeats, for instance).
924            If there are more than 20 of these errors, pcregrep is abandoned.
925    
926        (b) A binary zero was treated as data while matching, but terminated the
927            output line if it was written out. This has been fixed: binary zeroes
928            are now no different to any other data bytes.
929    
930        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
931            used to set a locale for matching. The --locale=xxxx long option has
932            been added (no short equivalent) to specify a locale explicitly on the
933            pcregrep command, overriding the environment variables.
934    
935        (d) When -B was used with -n, some line numbers in the output were one less
936            than they should have been.
937    
938        (e) Added the -o (--only-matching) option.
939    
940        (f) If -A or -C was used with -c (count only), some lines of context were
941            accidentally printed for the final match.
942    
943        (g) Added the -H (--with-filename) option.
944    
945        (h) The combination of options -rh failed to suppress file names for files
946            that were found from directory arguments.
947    
948        (i) Added the -D (--devices) and -d (--directories) options.
949    
950        (j) Added the -F (--fixed-strings) option.
951    
952        (k) Allow "-" to be used as a file name for -f as well as for a data file.
953    
954        (l) Added the --colo(u)r option.
955    
956        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
957            is not present by default.
958    
959     3. A nasty bug was discovered in the handling of recursive patterns, that is,
960        items such as (?R) or (?1), when the recursion could match a number of
961        alternatives. If it matched one of the alternatives, but subsequently,
962        outside the recursion, there was a failure, the code tried to back up into
963        the recursion. However, because of the way PCRE is implemented, this is not
964        possible, and the result was an incorrect result from the match.
965    
966        In order to prevent this happening, the specification of recursion has
967        been changed so that all such subpatterns are automatically treated as
968        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
969    
970     4. I had overlooked the fact that, in some locales, there are characters for
971        which isalpha() is true but neither isupper() nor islower() are true. In
972        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
973        and ordfeminine) are like this. This affected the treatment of \w and \W
974        when they appeared in character classes, but not when they appeared outside
975        a character class. The bit map for "word" characters is now created
976        separately from the results of isalnum() instead of just taking it from the
977        upper, lower, and digit maps. (Plus the underscore character, of course.)
978    
979     5. The above bug also affected the handling of POSIX character classes such as
980        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
981        permanent tables. Instead, the bit maps for such a class were previously
982        created as the appropriate unions of the upper, lower, and digit bitmaps.
983        Now they are created by subtraction from the [[:word:]] class, which has
984        its own bitmap.
985    
986     6. The [[:blank:]] character class matches horizontal, but not vertical space.
987        It is created by subtracting the vertical space characters (\x09, \x0a,
988        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
989        subtraction was done in the overall bitmap for a character class, meaning
990        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
991        be recognized. This bug has been fixed.
992    
993     7. Patches from the folks at Google:
994    
995          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
996          real life, but is still worth protecting against".
997    
998          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
999          regular expressions".
1000    
1001          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1002          have it.
1003    
1004          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1005          "configure" and the latter not, in order to fix a problem somebody had
1006          with compiling the Arg class on HP-UX.
1007    
1008          (e) Improve the error-handling of the C++ wrapper a little bit.
1009    
1010          (f) New tests for checking recursion limiting.
1011    
1012     8. The pcre_memmove() function, which is used only if the environment does not
1013        have a standard memmove() function (and is therefore rarely compiled),
1014        contained two bugs: (a) use of int instead of size_t, and (b) it was not
1015        returning a result (though PCRE never actually uses the result).
1016    
1017     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1018        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1019        returned instead of calling malloc() with an overflowing number that would
1020        most likely cause subsequent chaos.
1021    
1022    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1023    
1024    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
1025        with this option is matched, the nmatch and pmatch options of regexec() are
1026        ignored.
1027    
1028    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
1029        provided in case anyone wants to the the POSIX interface with UTF-8
1030        strings.
1031    
1032    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
1033        C++ linking (needed for some HP-UX environments).
1034    
1035    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
1036        (unused parameter) and in the pcre_printint() function (omitted "default"
1037        switch label when the default is to do nothing).
1038    
1039    15. Added some code to make it possible, when PCRE is compiled as a C++
1040        library, to replace subject pointers for pcre_exec() with a smart pointer
1041        class, thus making it possible to process discontinuous strings.
1042    
1043    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
1044        much the same function. They were added by different people who were trying
1045        to make PCRE easy to compile on non-Unix systems. It has been suggested
1046        that PCRE_EXPORT be abolished now that there is more automatic apparatus
1047        for compiling on Windows systems. I have therefore replaced it with
1048        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
1049        defaults to "extern" for C or "extern C" for C++, which works fine on
1050        Unix-like systems. It is now possible to override the value of PCRE_DATA_
1051        SCOPE with something explicit in config.h. In addition:
1052    
1053        (a) pcreposix.h still had just "extern" instead of either of these macros;
1054            I have replaced it with PCRE_DATA_SCOPE.
1055    
1056        (b) Functions such as _pcre_xclass(), which are internal to the library,
1057            but external in the C sense, all had PCRE_EXPORT in their definitions.
1058            This is apparently wrong for the Windows case, so I have removed it.
1059            (It makes no difference on Unix-like systems.)
1060    
1061    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
1062        of recursive calls to match(). This is different to MATCH_LIMIT because
1063        that limits the total number of calls to match(), not all of which increase
1064        the depth of recursion. Limiting the recursion depth limits the amount of
1065        stack (or heap if NO_RECURSE is set) that is used. The default can be set
1066        when PCRE is compiled, and changed at run time. A patch from Google adds
1067        this functionality to the C++ interface.
1068    
1069    18. Changes to the handling of Unicode character properties:
1070    
1071        (a) Updated the table to Unicode 4.1.0.
1072    
1073        (b) Recognize characters that are not in the table as "Cn" (undefined).
1074    
1075        (c) I revised the way the table is implemented to a much improved format
1076            which includes recognition of ranges. It now supports the ranges that
1077            are defined in UnicodeData.txt, and it also amalgamates other
1078            characters into ranges. This has reduced the number of entries in the
1079            table from around 16,000 to around 3,000, thus reducing its size
1080            considerably. I realized I did not need to use a tree structure after
1081            all - a binary chop search is just as efficient. Having reduced the
1082            number of entries, I extended their size from 6 bytes to 8 bytes to
1083            allow for more data.
1084    
1085        (d) Added support for Unicode script names via properties such as \p{Han}.
1086    
1087    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1088        matching that character.
1089    
1090    20. When matching a repeated Unicode property with a minimum greater than zero,
1091        (for example \pL{2,}), PCRE could look past the end of the subject if it
1092        reached it while seeking the minimum number of characters. This could
1093        happen only if some of the characters were more than one byte long, because
1094        there is a check for at least the minimum number of bytes.
1095    
1096    21. Refactored the implementation of \p and \P so as to be more general, to
1097        allow for more different types of property in future. This has changed the
1098        compiled form incompatibly. Anybody with saved compiled patterns that use
1099        \p or \P will have to recompile them.
1100    
1101    22. Added "Any" and "L&" to the supported property types.
1102    
1103    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1104        but give a compile time error if the value is greater than 0xff.
1105    
1106    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1107        accidentally not being installed or uninstalled.
1108    
1109    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1110        made were to insert the current release number. This seemed silly, because
1111        it made things harder for people building PCRE on systems that don't run
1112        "configure". I have turned pcre.h into a distributed file, no longer built
1113        by "configure", with the version identification directly included. There is
1114        no longer a pcre.h.in file.
1115    
1116        However, this change necessitated a change to the pcre-config script as
1117        well. It is built from pcre-config.in, and one of the substitutions was the
1118        release number. I have updated configure.ac so that ./configure now finds
1119        the release number by grepping pcre.h.
1120    
1121    26. Added the ability to run the tests under valgrind.
1122    
1123    
1124    Version 6.4 05-Sep-05
1125    ---------------------
1126    
1127     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1128        "--" to be printed when multiple files were scanned, even when none of the
1129        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1130        consider it to be a bug, and have restored the previous behaviour.
1131    
1132     2. A couple of code tidies to get rid of compiler warnings.
1133    
1134     3. The pcretest program used to cheat by referring to symbols in the library
1135        whose names begin with _pcre_. These are internal symbols that are not
1136        really supposed to be visible externally, and in some environments it is
1137        possible to suppress them. The cheating is now confined to including
1138        certain files from the library's source, which is a bit cleaner.
1139    
1140     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1141        file's purpose clearer.
1142    
1143     5. Reorganized pcre_ucp_findchar().
1144    
1145    
1146    Version 6.3 15-Aug-05
1147    ---------------------
1148    
1149     1. The file libpcre.pc.in did not have general read permission in the tarball.
1150    
1151     2. There were some problems when building without C++ support:
1152    
1153        (a) If C++ support was not built, "make install" and "make test" still
1154            tried to test it.
1155    
1156        (b) There were problems when the value of CXX was explicitly set. Some
1157            changes have been made to try to fix these, and ...
1158    
1159        (c) --disable-cpp can now be used to explicitly disable C++ support.
1160    
1161        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1162            backslash in a target when C++ was disabled. This confuses some
1163            versions of "make", apparently. Using an intermediate variable solves
1164            this. (Same for CPP_LOBJ.)
1165    
1166     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1167        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1168        necessary on certain architectures.
1169    
1170     4. Added a setting of -export-symbols-regex to the link command to remove
1171        those symbols that are exported in the C sense, but actually are local
1172        within the library, and not documented. Their names all begin with
1173        "_pcre_". This is not a perfect job, because (a) we have to except some
1174        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1175        available (and never for static libraries). I have made a note to try to
1176        find a way round (a) in the future.
1177    
1178    
1179    Version 6.2 01-Aug-05
1180    ---------------------
1181    
1182     1. There was no test for integer overflow of quantifier values. A construction
1183        such as {1111111111111111} would give undefined results. What is worse, if
1184        a minimum quantifier for a parenthesized subpattern overflowed and became
1185        negative, the calculation of the memory size went wrong. This could have
1186        led to memory overwriting.
1187    
1188     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1189    
1190     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1191        operating environments where this matters.
1192    
1193     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1194        PCRE options from within the C++ wrapper.
1195    
1196     5. Named capturing subpatterns were not being correctly counted when a pattern
1197        was compiled. This caused two problems: (a) If there were more than 100
1198        such subpatterns, the calculation of the memory needed for the whole
1199        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1200        back references of the form \12, where the number was greater than 9, were
1201        not recognized as back references, even though there were sufficient
1202        previous subpatterns.
1203    
1204     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1205        versions of gcc, e.g. 2.95.4.
1206    
1207    
1208    Version 6.1 21-Jun-05
1209    ---------------------
1210    
1211     1. There was one reference to the variable "posix" in pcretest.c that was not
1212        surrounded by "#if !defined NOPOSIX".
1213    
1214     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1215        the cross-check on the old pcre_info() function, for the benefit of the
1216        cut-down version of PCRE that is currently imported into Exim.
1217    
1218     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1219        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1220        patterns that start (?i) but I don't think that matters. The use of (?i) is
1221        just an example; this all applies to the other options as well.
1222    
1223     4. Since libtool seems to echo the compile commands it is issuing, the output
1224        from "make" can be reduced a bit by putting "@" in front of each libtool
1225        compile command.
1226    
1227     5. Patch from the folks at Google for configure.in to be a bit more thorough
1228        in checking for a suitable C++ installation before trying to compile the
1229        C++ stuff. This should fix a reported problem when a compiler was present,
1230        but no suitable headers.
1231    
1232     6. The man pages all had just "PCRE" as their title. I have changed them to
1233        be the relevant file name. I have also arranged that these names are
1234        retained in the file doc/pcre.txt, which is a concatenation in text format
1235        of all the man pages except the little individual ones for each function.
1236    
1237     7. The NON-UNIX-USE file had not been updated for the different set of source
1238        files that come with release 6. I also added a few comments about the C++
1239        wrapper.
1240    
1241    
1242    Version 6.0 07-Jun-05
1243    ---------------------
1244    
1245     1. Some minor internal re-organization to help with my DFA experiments.
1246    
1247     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1248        didn't matter for the library itself when fully configured, but did matter
1249        when compiling without UCP support, or within Exim, where the ucp files are
1250        not imported.
1251    
1252     3. Refactoring of the library code to split up the various functions into
1253        different source modules. The addition of the new DFA matching code (see
1254        below) to a single monolithic source would have made it really too
1255        unwieldy, quite apart from causing all the code to be include in a
1256        statically linked application, when only some functions are used. This is
1257        relevant even without the DFA addition now that patterns can be compiled in
1258        one application and matched in another.
1259    
1260        The downside of splitting up is that there have to be some external
1261        functions and data tables that are used internally in different modules of
1262        the library but which are not part of the API. These have all had their
1263        names changed to start with "_pcre_" so that they are unlikely to clash
1264        with other external names.
1265    
1266     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1267        a different (DFA) algorithm. Although it is slower than the original
1268        function, it does have some advantages for certain types of matching
1269        problem.
1270    
1271     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1272        including restarting after a partial match.
1273    
1274     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1275        defined when compiling for Windows was sent to me. I have put it into the
1276        code, though I have no means of testing or verifying it.
1277    
1278     7. Added the pcre_refcount() auxiliary function.
1279    
1280     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1281        match before or at the first newline in the subject string. In pcretest,
1282        the /f option on a pattern can be used to set this.
1283    
1284     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1285        would behave wrongly. This has been present in PCRE since release 4.0.
1286    
1287    10. A number of changes to the pcregrep command:
1288    
1289        (a) Refactored how -x works; insert ^(...)$ instead of setting
1290            PCRE_ANCHORED and checking the length, in preparation for adding
1291            something similar for -w.
1292    
1293        (b) Added the -w (match as a word) option.
1294    
1295        (c) Refactored the way lines are read and buffered so as to have more
1296            than one at a time available.
1297    
1298        (d) Implemented a pcregrep test script.
1299    
1300        (e) Added the -M (multiline match) option. This allows patterns to match
1301            over several lines of the subject. The buffering ensures that at least
1302            8K, or the rest of the document (whichever is the shorter) is available
1303            for matching (and similarly the previous 8K for lookbehind assertions).
1304    
1305        (f) Changed the --help output so that it now says
1306    
1307              -w, --word-regex(p)
1308    
1309            instead of two lines, one with "regex" and the other with "regexp"
1310            because that confused at least one person since the short forms are the
1311            same. (This required a bit of code, as the output is generated
1312            automatically from a table. It wasn't just a text change.)
1313    
1314        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1315            option but starts with a hyphen. Could be a pattern or a path name
1316            starting with a hyphen, for instance.
1317    
1318        (h) "-" can be given as a file name to represent stdin.
1319    
1320        (i) When file names are being printed, "(standard input)" is used for
1321            the standard input, for compatibility with GNU grep. Previously
1322            "<stdin>" was used.
1323    
1324        (j) The option --label=xxx can be used to supply a name to be used for
1325            stdin when file names are being printed. There is no short form.
1326    
1327        (k) Re-factored the options decoding logic because we are going to add
1328            two more options that take data. Such options can now be given in four
1329            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1330    
1331        (l) Added the -A, -B, and -C options for requesting that lines of context
1332            around matches be printed.
1333    
1334        (m) Added the -L option to print the names of files that do not contain
1335            any matching lines, that is, the complement of -l.
1336    
1337        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1338            continue to scan other files.
1339    
1340        (o) The -s option was incorrectly implemented. For compatibility with other
1341            greps, it now suppresses the error message for a non-existent or non-
1342            accessible file (but not the return code). There is a new option called
1343            -q that suppresses the output of matching lines, which was what -s was
1344            previously doing.
1345    
1346        (p) Added --include and --exclude options to specify files for inclusion
1347            and exclusion when recursing.
1348    
1349    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1350        Hopefully, it now does.
1351    
1352    12. Missing cast in pcre_study().
1353    
1354    13. Added an "uninstall" target to the makefile.
1355    
1356    14. Replaced "extern" in the function prototypes in Makefile.in with
1357        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1358        world, but is set differently for Windows.
1359    
1360    15. Added a second compiling function called pcre_compile2(). The only
1361        difference is that it has an extra argument, which is a pointer to an
1362        integer error code. When there is a compile-time failure, this is set
1363        non-zero, in addition to the error test pointer being set to point to an
1364        error message. The new argument may be NULL if no error number is required
1365        (but then you may as well call pcre_compile(), which is now just a
1366        wrapper). This facility is provided because some applications need a
1367        numeric error indication, but it has also enabled me to tidy up the way
1368        compile-time errors are handled in the POSIX wrapper.
1369    
1370    16. Added VPATH=.libs to the makefile; this should help when building with one
1371        prefix path and installing with another. (Or so I'm told by someone who
1372        knows more about this stuff than I do.)
1373    
1374    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1375        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1376        match everything, including newlines. This is not POSIX-compatible, but
1377        somebody wanted the feature. From pcretest it can be activated by using
1378        both the P and the s flags.
1379    
1380    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1381    
1382    19. libpcre.pc was being incorrectly installed as executable.
1383    
1384    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1385        it now also looks for '\r' so that it will work unmodified on Windows.
1386    
1387    21. Added Google's contributed C++ wrapper to the distribution.
1388    
1389    22. Added some untidy missing memory free() calls in pcretest, to keep
1390        Electric Fence happy when testing.
1391    
1392    
1393    
1394    Version 5.0 13-Sep-04
1395    ---------------------
1396    
1397     1. Internal change: literal characters are no longer packed up into items
1398        containing multiple characters in a single byte-string. Each character
1399        is now matched using a separate opcode. However, there may be more than one
1400        byte in the character in UTF-8 mode.
1401    
1402     2. The pcre_callout_block structure has two new fields: pattern_position and
1403        next_item_length. These contain the offset in the pattern to the next match
1404        item, and its length, respectively.
1405    
1406     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1407        insertion of callouts before each pattern item. Added the /C option to
1408        pcretest to make use of this.
1409    
1410     4. On the advice of a Windows user, the lines
1411    
1412          #if defined(_WIN32) || defined(WIN32)
1413          _setmode( _fileno( stdout ), 0x8000 );
1414          #endif  /* defined(_WIN32) || defined(WIN32) */
1415    
1416        have been added to the source of pcretest. This apparently does useful
1417        magic in relation to line terminators.
1418    
1419     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1420        for the benefit of those environments where the "b" makes a difference.
1421    
1422     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1423        to know about it. I have put a hack into configure.in that adds in code
1424        to set GCC=yes if CC=icc. This seems to end up at a point in the
1425        generated configure script that is early enough to affect the setting of
1426        compiler options, which is what is needed, but I have no means of testing
1427        whether it really works. (The user who reported this had patched the
1428        generated configure script, which of course I cannot do.)
1429    
1430        LATER: After change 22 below (new libtool files), the configure script
1431        seems to know about icc (and also ecc). Therefore, I have commented out
1432        this hack in configure.in.
1433    
1434     7. Added support for pkg-config (2 patches were sent in).
1435    
1436     8. Negated POSIX character classes that used a combination of internal tables
1437        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1438        [[:^ascii]]. Typically, they would match almost any characters. The other
1439        POSIX classes were not broken in this way.
1440    
1441     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1442        to find the match, as PCRE was deluded into thinking that the match had to
1443        start at the start point or following a newline. The same bug applied to
1444        patterns with negative forward assertions or any backward assertions
1445        preceding ".*" at the start, unless the pattern required a fixed first
1446        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1447    
1448    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1449        starting at the last subject character, bytes beyond the end of the subject
1450        string were read.
1451    
1452    11. Renamed the variable "class" as "classbits" to make life easier for C++
1453        users. (Previously there was a macro definition, but it apparently wasn't
1454        enough.)
1455    
1456    12. Added the new field "tables" to the extra data so that tables can be passed
1457        in at exec time, or the internal tables can be re-selected. This allows
1458        a compiled regex to be saved and re-used at a later time by a different
1459        program that might have everything at different addresses.
1460    
1461    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1462        -R library as well as a -L library.
1463    
1464    14. The debugging options of pcretest (-d on the command line or D on a
1465        pattern) showed incorrect output for anything following an extended class
1466        that contained multibyte characters and which was followed by a quantifier.
1467    
1468    15. Added optional support for general category Unicode character properties
1469        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1470        support. It adds about 90K to the size of the library. The meanings of the
1471        inbuilt class escapes such as \d and \s have NOT been changed.
1472    
1473    16. Updated pcredemo.c to include calls to free() to release the memory for the
1474        compiled pattern.
1475    
1476    17. The generated file chartables.c was being created in the source directory
1477        instead of in the building directory. This caused the build to fail if the
1478        source directory was different from the building directory, and was
1479        read-only.
1480    
1481    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1482        file. No doubt somebody will tell me if they don't make sense... Also added
1483        Dan Mooney's comments about building on OpenVMS.
1484    
1485    19. Added support for partial matching via the PCRE_PARTIAL option for
1486        pcre_exec() and the \P data escape in pcretest.
1487    
1488    20. Extended pcretest with 3 new pattern features:
1489    
1490        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1491              write the compiled pattern to the file whose name is "rest-of-line".
1492              This is a straight binary dump of the data, with the saved pointer to
1493              the character tables forced to be NULL. The study data, if any, is
1494              written too. After writing, pcretest reads a new pattern.
1495    
1496        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1497              compiled pattern from the given file. There must not be any
1498              occurrences of "<" in the file name (pretty unlikely); if there are,
1499              pcretest will instead treat the initial "<" as a pattern delimiter.
1500              After reading in the pattern, pcretest goes on to read data lines as
1501              usual.
1502    
1503        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1504              and 16-bit fields in a compiled pattern, to simulate a pattern that
1505              was compiled on a host of opposite endianness.
1506    
1507    21. The pcre-exec() function can now cope with patterns that were compiled on
1508        hosts of opposite endianness, with this restriction:
1509    
1510          As for any compiled expression that is saved and used later, the tables
1511          pointer field cannot be preserved; the extra_data field in the arguments
1512          to pcre_exec() should be used to pass in a tables address if a value
1513          other than the default internal tables were used at compile time.
1514    
1515    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1516        now diagnosed as an error. Previously, most of the time, a negative number
1517        would have been treated as zero, but if in addition "ovector" was passed as
1518        NULL, a crash could occur.
1519    
1520    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1521        new versions from the libtool 1.5 distribution (the last one is a copy of
1522        a file called libtool.m4). This seems to have fixed the need to patch
1523        "configure" to support Darwin 1.3 (which I used to do). However, I still
1524        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1525        workstation).
1526    
1527    24. Changed the PCRE licence to be the more standard "BSD" licence.
1528    
1529    
1530    Version 4.5 01-Dec-03
1531    ---------------------
1532    
1533     1. There has been some re-arrangement of the code for the match() function so
1534        that it can be compiled in a version that does not call itself recursively.
1535        Instead, it keeps those local variables that need separate instances for
1536        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1537        needs to "recurse". Keeping track of where control must go is done by means
1538        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1539        hide most of the details from the main code, and operates only if
1540        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1541        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1542        operating.
1543    
1544        To make it easier for callers to provide specially tailored get/free
1545        functions for this usage, two new functions, pcre_stack_malloc, and
1546        pcre_stack_free, are used. They are always called in strict stacking order,
1547        and the size of block requested is always the same.
1548    
1549        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1550        PCRE has been compiled to use the stack or the heap for recursion. The
1551        -C option of pcretest uses this to show which version is compiled.
1552    
1553        A new data escape \S, is added to pcretest; it causes the amounts of store
1554        obtained and freed by both kinds of malloc/free at match time to be added
1555        to the output.
1556    
1557     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1558        what's available on my current Linux desktop machine.
1559    
1560     3. When matching a UTF-8 string, the test for a valid string at the start has
1561        been extended. If start_offset is not zero, PCRE now checks that it points
1562        to a byte that is the start of a UTF-8 character. If not, it returns
1563        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1564        this is necessary because there may be backward assertions in the pattern.
1565        When matching the same subject several times, it may save resources to use
1566        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1567    
1568     4. The code for checking the validity of UTF-8 strings has been tightened so
1569        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1570        containing "overlong sequences".
1571    
1572     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1573        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1574        should have been "&", but it just so happened that all the cases this let
1575        through by mistake were picked up later in the function.
1576    
1577     6. I had used a variable called "isblank" - this is a C99 function, causing
1578        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1579    
1580     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1581        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1582        so the version is shown; (c) stop "make test" echoing "./RunTest".
1583    
1584     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1585    
1586     9. The prototype for memmove() for systems that don't have it was using
1587        size_t, but the inclusion of the header that defines size_t was later. I've
1588        moved the #includes for the C headers earlier to avoid this.
1589    
1590    10. Added some adjustments to the code to make it easier to compiler on certain
1591        special systems:
1592    
1593          (a) Some "const" qualifiers were missing.
1594          (b) Added the macro EXPORT before all exported functions; by default this
1595              is defined to be empty.
1596          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1597              that it reads its output file name as an argument instead of writing
1598              to the standard output and assuming this can be redirected.
1599    
1600    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1601        class containing characters with values greater than 255, PCRE compilation
1602        went into a loop.
1603    
1604    12. A recursive reference to a subpattern that was within another subpattern
1605        that had a minimum quantifier of zero caused PCRE to crash. For example,
1606        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1607        recursion. If the recursively-called subpattern itself had a zero repeat,
1608        that was OK.
1609    
1610    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1611        buffer into which it was copied (for escape processing) was still set at
1612        1024, so long lines caused crashes.
1613    
1614    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1615        "internal error: code overflow...". This applied to any character class
1616        that was followed by a possessive quantifier.
1617    
1618    15. Modified the Makefile to add libpcre.la as a prerequisite for
1619        libpcreposix.la because I was told this is needed for a parallel build to
1620        work.
1621    
1622    16. If a pattern that contained .* following optional items at the start was
1623        studied, the wrong optimizing data was generated, leading to matching
1624        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1625        matching string must start with a or b or c. The correct conclusion for
1626        this pattern is that a match can start with any character.
1627    
1628    
1629    Version 4.4 13-Aug-03
1630    ---------------------
1631    
1632     1. In UTF-8 mode, a character class containing characters with values between
1633        127 and 255 was not handled correctly if the compiled pattern was studied.
1634        In fixing this, I have also improved the studying algorithm for such
1635        classes (slightly).
1636    
1637     2. Three internal functions had redundant arguments passed to them. Removal
1638        might give a very teeny performance improvement.
1639    
1640     3. Documentation bug: the value of the capture_top field in a callout is *one
1641        more than* the number of the hightest numbered captured substring.
1642    
1643     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1644        in incorrectly linking with a previously installed version. They now link
1645        explicitly with libpcre.la.
1646    
1647     5. configure.in no longer needs to recognize Cygwin specially.
1648    
1649     6. A problem in pcre.in for Windows platforms is fixed.
1650    
1651     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1652        pcretest, it used to include the size of the study block as part of its
1653        output. Unfortunately, the structure contains a field that has a different
1654        size on different hardware architectures. This meant that the tests that
1655        showed this size failed. As the block is currently always of a fixed size,
1656        this information isn't actually particularly useful in pcretest output, so
1657        I have just removed it.
1658    
1659     8. Three pre-processor statements accidentally did not start in column 1.
1660        Sadly, there are *still* compilers around that complain, even though
1661        standard C has not required this for well over a decade. Sigh.
1662    
1663     9. In pcretest, the code for checking callouts passed small integers in the
1664        callout_data field, which is a void * field. However, some picky compilers
1665        complained about the casts involved for this on 64-bit systems. Now
1666        pcretest passes the address of the small integer instead, which should get
1667        rid of the warnings.
1668    
1669    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1670        both compile and run time, and gives an error if an invalid UTF-8 sequence
1671        is found. There is a option for disabling this check in cases where the
1672        string is known to be correct and/or the maximum performance is wanted.
1673    
1674    11. In response to a bug report, I changed one line in Makefile.in from
1675    
1676            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1677        to
1678            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1679    
1680        to look similar to other lines, but I have no way of telling whether this
1681        is the right thing to do, as I do not use Windows. No doubt I'll get told
1682        if it's wrong...
1683    
1684    
1685    Version 4.3 21-May-03
1686    ---------------------
1687    
1688    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1689       Makefile.
1690    
1691    2. Some refactoring to improve the quality of the code:
1692    
1693       (i)   The utf8_table... variables are now declared "const".
1694    
1695       (ii)  The code for \cx, which used the "case flipping" table to upper case
1696             lower case letters, now just substracts 32. This is ASCII-specific,
1697             but the whole concept of \cx is ASCII-specific, so it seems
1698             reasonable.
1699    
1700       (iii) PCRE was using its character types table to recognize decimal and
1701             hexadecimal digits in the pattern. This is silly, because it handles
1702             only 0-9, a-f, and A-F, but the character types table is locale-
1703             specific, which means strange things might happen. A private
1704             table is now used for this - though it costs 256 bytes, a table is
1705             much faster than multiple explicit tests. Of course, the standard
1706             character types table is still used for matching digits in subject
1707             strings against \d.
1708    
1709       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1710             ending in _t are). So I've renamed it as ESC_tee.
1711    
1712    3. The first argument for regexec() in the POSIX wrapper should have been
1713       defined as "const".
1714    
1715    4. Changed pcretest to use malloc() for its buffers so that they can be
1716       Electric Fenced for debugging.
1717    
1718    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1719       to read one or more bytes before the start of the subject string. Often this
1720       had no effect on PCRE's behaviour, but in some circumstances it could
1721       provoke a segmentation fault.
1722    
1723    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1724       to try to read one or more bytes before the start of the subject string.
1725    
1726    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1727       UTF-8 support could misbehave in various ways if the subject string
1728       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1729       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1730       back over UTF-8 characters.)
1731    
1732    
1733    Version 4.2 14-Apr-03
1734    ---------------------
1735    
1736    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1737    
1738    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1739         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1740         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1741         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1742         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1743           and BUILD_EXEEXT
1744         Note: automatic setting of the BUILD variables is not yet working
1745         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1746           compile-time but not at link-time
1747         [LINK]: use for linking executables only
1748         make different versions for Windows and non-Windows
1749         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1750           libraries
1751         [LINK_FOR_BUILD]: new variable
1752         [OBJEXT]: use throughout
1753         [EXEEXT]: use throughout
1754         <winshared>: new target
1755         <wininstall>: new target
1756         <dftables.o>: use native compiler
1757         <dftables>: use native linker
1758         <install>: handle Windows platform correctly
1759         <clean>: ditto
1760         <check>: ditto
1761         copy DLL to top builddir before testing
1762    
1763       As part of these changes, -no-undefined was removed again. This was reported
1764       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1765       in any case.
1766    
1767    3. Some tidies to get rid of compiler warnings:
1768    
1769       . In the match_data structure, match_limit was an unsigned long int, whereas
1770         match_call_count was an int. I've made them both unsigned long ints.
1771    
1772       . In pcretest the fact that a const uschar * doesn't automatically cast to
1773         a void * provoked a warning.
1774    
1775       . Turning on some more compiler warnings threw up some "shadow" variables
1776         and a few more missing casts.
1777    
1778    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1779       option, a class that contained a single character with a value between 128
1780       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1781    
1782    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1783       option, a class that contained several characters, but with at least one
1784       whose value was between 128 and 255 caused PCRE to crash.
1785    
1786    
1787    Version 4.1 12-Mar-03
1788    ---------------------
1789    
1790    1. Compiling with gcc -pedantic found a couple of places where casts were
1791    needed, and a string in dftables.c that was longer than standard compilers are
1792    required to support.
1793    
1794    2. Compiling with Sun's compiler found a few more places where the code could
1795    be tidied up in order to avoid warnings.
1796    
1797    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1798    first of these names is deprecated in the latest Autoconf in favour of the name
1799    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1800    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1801    analogy I have changed it to CFLAGS_FOR_BUILD.
1802    
1803    4. Added -no-undefined to the linking command in the Makefile, because this is
1804    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1805    linking step for the pcreposix library.
1806    
1807    5. PCRE was failing to diagnose the case of two named groups with the same
1808    name.
1809    
1810    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1811    literal character that is needed in the subject for a match, and scans along to
1812    ensure that it is present before embarking on the full matching process. This
1813    saves time in cases of nested unlimited repeats that are never going to match.
1814    Problem: the scan can take a lot of time if the subject is very long (e.g.
1815    megabytes), thus penalizing straightforward matches. It is now done only if the
1816    amount of subject to be scanned is less than 1000 bytes.
1817    
1818    7. A lesser problem with the same optimization is that it was recording the
1819    first character of an anchored pattern as "needed", thus provoking a search
1820    right along the subject, even when the first match of the pattern was going to
1821    fail. The "needed" character is now not set for anchored patterns, unless it
1822    follows something in the pattern that is of non-fixed length. Thus, it still
1823    fulfils its original purpose of finding quick non-matches in cases of nested
1824    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1825    
1826    
1827    Version 4.0 17-Feb-03
1828    ---------------------
1829    
1830    1. If a comment in an extended regex that started immediately after a meta-item
1831    extended to the end of string, PCRE compiled incorrect data. This could lead to
1832    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1833    
1834    2. Moved to autoconf 2.53 and libtool 1.4.2.
1835    
1836    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1837    the special perltest8 script is no longer needed - all the tests can be run
1838    from a single perltest script.
1839    
1840    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1841    by \s. It has now been removed in PCRE. This means it isn't recognized as
1842    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1843    class [:space:] *does* include VT, thereby creating a mess.
1844    
1845    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1846    space and tab.
1847    
1848    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1849    its new features into the main test script, reducing the number of scripts.
1850    
1851    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1852    were backward compatible, and made the (?i) apply to the whole pattern, as if
1853    /i were given. Now it behaves more logically, and applies the option setting
1854    only to what follows. PCRE has been changed to follow suit. However, if it
1855    finds options settings right at the start of the pattern, it extracts them into
1856    the global options, as before. Thus, they show up in the info data.
1857    
1858    8. Added support for the \Q...\E escape sequence. Characters in between are
1859    treated as literals. This is slightly different from Perl in that $ and @ are
1860    also handled as literals inside the quotes. In Perl, they will cause variable
1861    interpolation. Note the following examples:
1862    
1863        Pattern            PCRE matches      Perl matches
1864    
1865        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
1866        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
1867        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
1868    
1869    For compatibility with Perl, \Q...\E sequences are recognized inside character
1870    classes as well as outside them.
1871    
1872    9. Re-organized 3 code statements in pcretest to avoid "overflow in
1873    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1874    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1875    signed/unsigned warnings.
1876    
1877    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1878    option for pcretest, so I've replaced it by a simple function that does just
1879    that job.
1880    
1881    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1882    "pcregrep -".
1883    
1884    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1885    Java package. This provides some syntactic sugar for simple cases of what my
1886    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1887    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1888    item, you can use this simplified notation. Note that only makes sense with
1889    greedy quantifiers. Consequently, the use of the possessive quantifier forces
1890    greediness, whatever the setting of the PCRE_UNGREEDY option.
1891    
1892    13. A change of greediness default within a pattern was not taking effect at
1893    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1894    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1895    was abstracted outside.
1896    
1897    14. PCRE now supports the \G assertion. It is true when the current matching
1898    position is at the start point of the match. This differs from \A when the
1899    starting offset is non-zero. Used with the /g option of pcretest (or similar
1900    code), it works in the same way as it does for Perl's /g option. If all
1901    alternatives of a regex begin with \G, the expression is anchored to the start
1902    match position, and the "anchored" flag is set in the compiled expression.
1903    
1904    15. Some bugs concerning the handling of certain option changes within patterns
1905    have been fixed. These applied to options other than (?ims). For example,
1906    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1907    been the other way round. Some of this was related to change 7 above.
1908    
1909    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1910    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1911    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1912    POSIX classes only within a class (e.g. /[[:alpha:]]/).
1913    
1914    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1915    mode. Unlike ".", it always matches newline, whatever the setting of
1916    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1917    assertions. Perl allows it, but it doesn't (in general) work because it can't
1918    calculate the length of the lookbehind. At least, that's the case for Perl
1919    5.8.0 - I've been told they are going to document that it doesn't work in
1920    future.
1921    
1922    18. Added an error diagnosis for escapes that PCRE does not support: these are
1923    \L, \l, \N, \P, \p, \U, \u, and \X.
1924    
1925    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1926    reading past the end of the pattern in cases such as /[abcd/.
1927    
1928    20. PCRE was getting more memory than necessary for patterns with classes that
1929    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1930    
1931    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1932    compiling PCRE for use with Virtual Pascal.
1933    
1934    22. Small fix to the Makefile to make it work properly if the build is done
1935    outside the source tree.
1936    
1937    23. Added a new extension: a condition to go with recursion. If a conditional
1938    subpattern starts with (?(R) the "true" branch is used if recursion has
1939    happened, whereas the "false" branch is used only at the top level.
1940    
1941    24. When there was a very long string of literal characters (over 255 bytes
1942    without UTF support, over 250 bytes with UTF support), the computation of how
1943    much memory was required could be incorrect, leading to segfaults or other
1944    strange effects.
1945    
1946    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1947    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1948    there was a subsequent back reference to those brackets. This meant that, for
1949    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1950    possible to check for precisely this case. All we can do is abandon the
1951    optimization if .* occurs inside capturing brackets when there are any back
1952    references whatsoever. (See below for a better fix that came later.)
1953    
1954    26. The handling of the optimization for finding the first character of a
1955    non-anchored pattern, and for finding a character that is required later in the
1956    match were failing in some cases. This didn't break the matching; it just
1957    failed to optimize when it could. The way this is done has been re-implemented.
1958    
1959    27. Fixed typo in error message for invalid (?R item (it said "(?p").
1960    
1961    28. Added a new feature that provides some of the functionality that Perl
1962    provides with (?{...}). The facility is termed a "callout". The way it is done
1963    in PCRE is for the caller to provide an optional function, by setting
1964    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1965    global variable. By default it is unset, which disables all calling out. To get
1966    the function called, the regex must include (?C) at appropriate points. This
1967    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1968    This provides a means of identifying different callout points. When PCRE
1969    reaches such a point in the regex, if pcre_callout has been set, the external
1970    function is called. It is provided with data in a structure called
1971    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1972    matching continues; if it returns a non-zero value, the match at the current
1973    point fails. However, backtracking will occur if possible. [This was changed
1974    later and other features added - see item 49 below.]
1975    
1976    29. pcretest is upgraded to test the callout functionality. It provides a
1977    callout function that displays information. By default, it shows the start of
1978    the match and the current position in the text. There are some new data escapes
1979    to vary what happens:
1980    
1981        \C+         in addition, show current contents of captured substrings
1982        \C-         do not supply a callout function
1983        \C!n        return 1 when callout number n is reached
1984        \C!n!m      return 1 when callout number n is reached for the mth time
1985    
1986    30. If pcregrep was called with the -l option and just a single file name, it
1987    output "<stdin>" if a match was found, instead of the file name.
1988    
1989    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1990    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1991    pcre_exec(). This saves a malloc/free per call. The default value of
1992    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1993    when configuring.
1994    
1995    32. The default maximum size of a compiled pattern is 64K. There have been a
1996    few cases of people hitting this limit. The code now uses macros to handle the
1997    storing of links as offsets within the compiled pattern. It defaults to 2-byte
1998    links, but this can be changed to 3 or 4 bytes by --with-link-size when
1999    configuring. Tests 2 and 5 work only with 2-byte links because they output
2000    debugging information about compiled patterns.
2001    
2002    33. Internal code re-arrangements:
2003    
2004    (a) Moved the debugging function for printing out a compiled regex into
2005        its own source file (printint.c) and used #include to pull it into
2006        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
2007        separate copies.
2008    
2009    (b) Defined the list of op-code names for debugging as a macro in
2010        internal.h so that it is next to the definition of the opcodes.
2011    
2012    (c) Defined a table of op-code lengths for simpler skipping along compiled
2013        code. This is again a macro in internal.h so that it is next to the
2014        definition of the opcodes.
2015    
2016    34. Added support for recursive calls to individual subpatterns, along the
2017    lines of Robin Houston's patch (but implemented somewhat differently).
2018    
2019    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
2020    allow it to read and process whole directories in Win32. This code was
2021    contributed by Lionel Fourquaux; it has not been tested by me.
2022    
2023    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
2024    used to name a group. Names consist of alphanumerics and underscores, and must
2025    be unique. Back references use the syntax (?P=name) and recursive calls use
2026    (?P>name) which is a PCRE extension to the Python extension. Groups still have
2027    numbers. The function pcre_fullinfo() can be used after compilation to extract
2028    a name/number map. There are three relevant calls:
2029    
2030      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
2031      PCRE_INFO_NAMECOUNT            yields the number of entries
2032      PCRE_INFO_NAMETABLE            yields a pointer to the map.
2033    
2034    The map is a vector of fixed-size entries. The size of each entry depends on
2035    the length of the longest name used. The first two bytes of each entry are the
2036    group number, most significant byte first. There follows the corresponding
2037    name, zero terminated. The names are in alphabetical order.
2038    
2039    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
2040    case instead of 255. Making it the same both with and without UTF-8 support
2041    means that the same test output works with both.
2042    
2043    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
2044    calling malloc() with a zero argument.
2045    
2046    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
2047    optimization. I've improved things by keeping a bitmap of backreferences with
2048    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
2049    fact referenced, the optimization can be applied. It is unlikely that a
2050    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
2051    the match to follow \n) will appear inside brackets with a number greater than
2052    31, but if it does, any back reference > 31 suppresses the optimization.
2053    
2054    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
2055    of disabling numbered capturing parentheses. Any opening parenthesis that is
2056    not followed by ? behaves as if it were followed by ?: but named parentheses
2057    can still be used for capturing (and they will acquire numbers in the usual
2058    way).
2059    
2060    41. Redesigned the return codes from the match() function into yes/no/error so
2061    that errors can be passed back from deep inside the nested calls. A malloc
2062    failure while inside a recursive subpattern call now causes the
2063    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
2064    
2065    42. It is now possible to set a limit on the number of times the match()
2066    function is called in a call to pcre_exec(). This facility makes it possible to
2067    limit the amount of recursion and backtracking, though not in a directly
2068    obvious way, because the match() function is used in a number of different
2069    circumstances. The count starts from zero for each position in the subject
2070    string (for non-anchored patterns). The default limit is, for compatibility, a
2071    large number, namely 10 000 000. You can change this in two ways:
2072    
2073    (a) When configuring PCRE before making, you can use --with-match-limit=n
2074        to set a default value for the compiled library.
2075    
2076    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
2077        a different value is set. See 45 below.
2078    
2079    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
2080    
2081    43. Added a new function pcre_config(int, void *) to enable run-time extraction
2082    of things that can be changed at compile time. The first argument specifies
2083    what is wanted and the second points to where the information is to be placed.
2084    The current list of available information is:
2085    
2086      PCRE_CONFIG_UTF8
2087    
2088    The output is an integer that is set to one if UTF-8 support is available;
2089    otherwise it is set to zero.
2090    
2091      PCRE_CONFIG_NEWLINE
2092    
2093    The output is an integer that it set to the value of the code that is used for
2094    newline. It is either LF (10) or CR (13).
2095    
2096      PCRE_CONFIG_LINK_SIZE
2097    
2098    The output is an integer that contains the number of bytes used for internal
2099    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
2100    
2101      PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
2102    
2103    The output is an integer that contains the threshold above which the POSIX
2104    interface uses malloc() for output vectors. See item 31 above.
2105    
2106      PCRE_CONFIG_MATCH_LIMIT
2107    
2108    The output is an unsigned integer that contains the default limit of the number
2109    of match() calls in a pcre_exec() execution. See 42 above.
2110    
2111    44. pcretest has been upgraded by the addition of the -C option. This causes it
2112    to extract all the available output from the new pcre_config() function, and to
2113    output it. The program then exits immediately.
2114    
2115    45. A need has arisen to pass over additional data with calls to pcre_exec() in
2116    order to support additional features. One way would have been to define
2117    pcre_exec2() (for example) with extra arguments, but this would not have been
2118    extensible, and would also have required all calls to the original function to
2119    be mapped to the new one. Instead, I have chosen to extend the mechanism that
2120    is used for passing in "extra" data from pcre_study().
2121    
2122    The pcre_extra structure is now exposed and defined in pcre.h. It currently
2123    contains the following fields:
2124    
2125      flags         a bitmap indicating which of the following fields are set
2126      study_data    opaque data from pcre_study()
2127      match_limit   a way of specifying a limit on match() calls for a specific
2128                      call to pcre_exec()
2129      callout_data  data for callouts (see 49 below)
2130    
2131    The flag bits are also defined in pcre.h, and are
2132    
2133      PCRE_EXTRA_STUDY_DATA
2134      PCRE_EXTRA_MATCH_LIMIT
2135      PCRE_EXTRA_CALLOUT_DATA
2136    
2137    The pcre_study() function now returns one of these new pcre_extra blocks, with
2138    the actual study data pointed to by the study_data field, and the
2139    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
2140    before. That is, this change is entirely upwards-compatible and requires no
2141    change to existing code.
2142    
2143    If you want to pass in additional data to pcre_exec(), you can either place it
2144    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2145    block.
2146    
2147    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2148    data string contains the escape sequence \M, pcretest calls pcre_exec() several
2149    times with different match limits, until it finds the minimum value needed for
2150    pcre_exec() to complete. The value is then output. This can be instructive; for
2151    most simple matches the number is quite small, but for pathological cases it
2152    gets very large very quickly.
2153    
2154    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2155    returns the size of the data block pointed to by the study_data field in a
2156    pcre_extra block, that is, the value that was passed as the argument to
2157    pcre_malloc() when PCRE was getting memory in which to place the information
2158    created by pcre_study(). The fourth argument should point to a size_t variable.
2159    pcretest has been extended so that this information is shown after a successful
2160    pcre_study() call when information about the compiled regex is being displayed.
2161    
2162    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2163    because what follows is always an absolute path. (Later: it turns out that this
2164    is more than cosmetic for MinGW, because it doesn't like empty path
2165    components.)
2166    
2167    49. Some changes have been made to the callout feature (see 28 above):
2168    
2169    (i)  A callout function now has three choices for what it returns:
2170    
2171           0  =>  success, carry on matching
2172         > 0  =>  failure at this point, but backtrack if possible
2173         < 0  =>  serious error, return this value from pcre_exec()
2174    
2175         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2176         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2177         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2178         use by callout functions. It will never be used by PCRE itself.
2179    
2180    (ii) The pcre_extra structure (see 45 above) has a void * field called
2181         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2182         pcre_callout_block structure has a field of the same name. The contents of
2183         the field passed in the pcre_extra structure are passed to the callout
2184         function in the corresponding field in the callout block. This makes it
2185         easier to use the same callout-containing regex from multiple threads. For
2186         testing, the pcretest program has a new data escape
2187    
2188           \C*n        pass the number n (may be negative) as callout_data
2189    
2190         If the callout function in pcretest receives a non-zero value as
2191         callout_data, it returns that value.
2192    
2193    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2194    there were some redundant $(CFLAGS) in commands that are now specified as
2195    $(LINK), which already includes $(CFLAGS).
2196    
2197    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2198    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2199    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2200    one-byte characters throughout. Note that case-insensitive matching applies
2201    only to characters whose values are less than 256. PCRE doesn't support the
2202    notion of cases for higher-valued characters.
2203    
2204    (i)   A character class whose characters are all within 0-255 is handled as
2205          a bit map, and the map is inverted for negative classes. Previously, a
2206          character > 255 always failed to match such a class; however it should
2207          match if the class was a negative one (e.g. [^ab]). This has been fixed.
2208    
2209    (ii)  A negated character class with a single character < 255 is coded as
2210          "not this character" (OP_NOT). This wasn't working properly when the test
2211          character was multibyte, either singly or repeated.
2212    
2213    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2214          mode, for example: \x{100}{2,3}.
2215    
2216    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2217          singly or repeated) now correctly test multibyte characters. However,
2218          PCRE doesn't recognize any characters with values greater than 255 as
2219          digits, spaces, or word characters. Such characters always match \D, \S,
2220          and \W, and never match \d, \s, or \w.
2221    
2222    (v)   Classes may now contain characters and character ranges with values
2223          greater than 255. For example: [ab\x{100}-\x{400}].
2224    
2225    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
2226          PCRE in UTF-8 mode.
2227    
2228    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2229    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2230    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2231    value.)
2232    
2233    53. The single man page has become too large. I have therefore split it up into
2234    a number of separate man pages. These also give rise to individual HTML pages;
2235    these are now put in a separate directory, and there is an index.html page that
2236    lists them all. Some hyperlinking between the pages has been installed.
2237    
2238    54. Added convenience functions for handling named capturing parentheses.
2239    
2240    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2241    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2242    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2243    are faulted.
2244    
2245    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2246    calling configure. These values are used when compiling the dftables.c program
2247    which is run to generate the source of the default character tables. They
2248    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2249    you will need to set these values.
2250    
2251    57. Updated the building process for Windows DLL, as provided by Fred Cox.
2252    
2253    
2254    Version 3.9 02-Jan-02
2255    ---------------------
2256    
2257    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
2258    
2259    2. If --disable-static was given, the building process failed when trying to
2260    build pcretest and pcregrep. (For some reason it was using libtool to compile
2261    them, which is not right, as they aren't part of the library.)
2262    
2263    
2264    Version 3.8 18-Dec-01
2265    ---------------------
2266    
2267    1. The experimental UTF-8 code was completely screwed up. It was packing the
2268    bytes in the wrong order. How dumb can you get?
2269    
2270    
2271    Version 3.7 29-Oct-01
2272    ---------------------
2273    
2274    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
2275    This caused pcretest, when used on the test data, to segfault. Unfortunately,
2276    this didn't happen under Solaris 8, where I normally test things.
2277    
2278    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
2279    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
2280    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
2281    this fix an hour or so after the initial 3.7 release.)
2282    
2283    
2284    Version 3.6 23-Oct-01
2285    ---------------------
2286    
2287    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
2288    offsets passed as NULL with zero offset count.
2289    
2290    2. The config.guess and config.sub files had not been updated when I moved to
2291    the latest autoconf.
2292    
2293    
2294    Version 3.5 15-Aug-01
2295    ---------------------
2296    
2297    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2298    had been forgotten.
2299    
2300    2. By using declared but undefined structures, we can avoid using "void"
2301    definitions in pcre.h while keeping the internal definitions of the structures
2302    private.
2303    
2304    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2305    user point of view, this means that both static and shared libraries are built
2306    by default, but this can be individually controlled. More of the work of
2307    handling this static/shared cases is now inside libtool instead of PCRE's make
2308    file.
2309    
2310    4. The pcretest utility is now installed along with pcregrep because it is
2311    useful for users (to test regexs) and by doing this, it automatically gets
2312    relinked by libtool. The documentation has been turned into a man page, so
2313    there are now .1, .txt, and .html versions in /doc.
2314    
2315    5. Upgrades to pcregrep:
2316       (i)   Added long-form option names like gnu grep.
2317       (ii)  Added --help to list all options with an explanatory phrase.
2318       (iii) Added -r, --recursive to recurse into sub-directories.
2319       (iv)  Added -f, --file to read patterns from a file.
2320    
2321    6. pcre_exec() was referring to its "code" argument before testing that
2322    argument for NULL (and giving an error if it was NULL).
2323    
2324    7. Upgraded Makefile.in to allow for compiling in a different directory from
2325    the source directory.
2326    
2327    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2328    options bits, the pointer it was passed was to an int instead of to an unsigned
2329    long int. This mattered only on 64-bit systems.
2330    
2331    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2332    generated) instead of pcre.in, which it its source. Also made the same change
2333    in several of the .c files.
2334    
2335    10. A new release of gcc defines printf() as a macro, which broke pcretest
2336    because it had an ifdef in the middle of a string argument for printf(). Fixed
2337    by using separate calls to printf().
2338    
2339    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2340    script, to force use of CR or LF instead of \n in the source. On non-Unix
2341    systems, the value can be set in config.h.
2342    
2343    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2344    absolute limit. Changed the text of the error message to make this clear, and
2345    likewise updated the man page.
2346    
2347    13. The limit of 99 on the number of capturing subpatterns has been removed.
2348    The new limit is 65535, which I hope will not be a "real" limit.
2349    
2350    
2351    Version 3.4 22-Aug-00
2352    ---------------------
2353    
2354    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2355    
2356    2. Diagnose condition (?(0) as an error instead of crashing on matching.
2357    
2358    
2359    Version 3.3 01-Aug-00
2360    ---------------------
2361    
2362    1. If an octal character was given, but the value was greater than \377, it
2363    was not getting masked to the least significant bits, as documented. This could
2364    lead to crashes in some systems.
2365    
2366    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2367    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2368    
2369    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2370    These just pass their arguments on to (pcre_free)(), but they are provided
2371    because some uses of PCRE bind it to non-C systems that can call its functions,
2372    but cannot call free() or pcre_free() directly.
2373    
2374    4. Add "make test" as a synonym for "make check". Corrected some comments in
2375    the Makefile.
2376    
2377    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2378    Makefile.
2379    
2380    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2381    command called pgrep for grepping around the active processes.
2382    
2383    7. Added the beginnings of support for UTF-8 character strings.
2384    
2385    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2386    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2387    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2388    out for the ar command.)
2389    
2390    
2391    Version 3.2 12-May-00
2392    ---------------------
2393    
2394    This is purely a bug fixing release.
2395    
2396    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
2397    of ZA. This was just one example of several cases that could provoke this bug,
2398    which was introduced by change 9 of version 2.00. The code for breaking
2399    infinite loops after an iteration that matches an empty string was't working
2400    correctly.
2401    
2402    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
2403    when matched against abbab (for example). After matching an empty string, it
2404    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
2405    caused it to match further down the string than it should.
2406    
2407    3. The code contained an inclusion of sys/types.h. It isn't clear why this
2408    was there because it doesn't seem to be needed, and it causes trouble on some
2409    systems, as it is not a Standard C header. It has been removed.
2410    
2411    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
2412    were reported on the Macintosh. The changes were from
2413    
2414      while ((c = *(++ptr)) != 0 && c != '\n');
2415    to
2416      while ((c = *(++ptr)) != 0 && c != '\n') ;
2417    
2418    Totally extraordinary, but if that's what it takes...
2419    
2420    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2421    available. Added HAVE_BCOPY and an autoconf test for it; if neither
2422    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2423    assumes the way PCRE uses memmove() (always moving upwards).
2424    
2425    6. PCRE is being used in one environment where strchr() is not available. There
2426    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2427    faster code anyway.
2428    
2429    
2430    Version 3.1 09-Feb-00
2431    ---------------------
2432    
2433    The only change in this release is the fixing of some bugs in Makefile.in for
2434    the "install" target:
2435    
2436    (1) It was failing to install pcreposix.h.
2437    
2438    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2439    
2440    
2441    Version 3.0 01-Feb-00
2442    ---------------------
2443    
2444    1. Add support for the /+ modifier to perltest (to output $` like it does in
2445    pcretest).
2446    
2447    2. Add support for the /g modifier to perltest.
2448    
2449    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2450    matches null strings.
2451    
2452    4. Fix perltest so that it doesn't do unwanted things when fed an empty
2453    pattern. Perl treats empty patterns specially - it reuses the most recent
2454    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2455    effect.
2456    
2457    5. The POSIX interface was broken in that it was just handing over the POSIX
2458    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2459    required a bigger vector, with some working space on the end. This means that
2460    the POSIX wrapper now has to get and free some memory, and copy the results.
2461    
2462    6. Added some simple autoconf support, placing the test data and the
2463    documentation in separate directories, re-organizing some of the
2464    information files, and making it build pcre-config (a GNU standard). Also added
2465    libtool support for building PCRE as a shared library, which is now the
2466    default.
2467    
2468    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2469    09 are not valid octal constants. Single digits will be used for minor values
2470    less than 10.
2471    
2472    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2473    existing programs that set these in the POSIX interface can use PCRE without
2474    modification.
2475    
2476    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2477    return all that pcre_info() returns, plus additional data. The pcre_info()
2478    function is retained for compatibility, but is considered to be obsolete.
2479    
2480    10. Added experimental recursion feature (?R) to handle one common case that
2481    Perl 5.6 will be able to do with (?p{...}).
2482    
2483    11. Added support for POSIX character classes like [:alpha:], which Perl is
2484    adopting.
2485    
2486    
2487    Version 2.08 31-Aug-99
2488    ----------------------
2489    
2490    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2491    trying to match at the startoffset position, but instead was moving forward to
2492    the next newline as if a previous match had failed.
2493    
2494    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2495    and could get into a loop if a null string was matched other than at the start
2496    of the subject.
2497    
2498    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2499    be distinguished at compile time, and for completeness also added PCRE_DATE.
2500    
2501    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2502    in GnuWin32 environments.
2503    
2504    
2505    Version 2.07 29-Jul-99
2506    ----------------------
2507    
2508    1. The documentation is now supplied in plain text form and HTML as well as in
2509    the form of man page sources.
2510    
2511    2. C++ compilers don't like assigning (void *) values to other pointer types.
2512    In particular this affects malloc(). Although there is no problem in Standard
2513    C, I've put in casts to keep C++ compilers happy.
2514    
2515    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2516    should be (const char *).
2517    
2518    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2519    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2520    However, I haven't made this a standard facility. The documentation doesn't
2521    mention it, and the Makefile doesn't support it.
2522    
2523    5. The Makefile now contains an "install" target, with editable destinations at
2524    the top of the file. The pcretest program is not installed.
2525    
2526    6. pgrep -V now gives the PCRE version number and date.
2527    
2528    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2529    causing the entire string to be ignored, instead of just the last character.
2530    
2531    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2532    non-matching string, it can take a very, very long time, even for strings of
2533    quite modest length, because of the nested recursion. PCRE now does better in
2534    some of these cases. It does this by remembering the last required literal
2535    character in the pattern, and pre-searching the subject to ensure it is present
2536    before running the real match. In other words, it applies a heuristic to detect
2537    some types of certain failure quickly, and in the above example, if presented
2538    with a string that has no trailing " it gives "no match" very quickly.
2539    
2540    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2541    other alternatives are tried instead.
2542    
2543    
2544    Version 2.06 09-Jun-99
2545    ----------------------
2546    
2547    1. Change pcretest's output for amount of store used to show just the code
2548    space, because the remainder (the data block) varies in size between 32-bit and
2549    64-bit systems.
2550    
2551    2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2552    start matching at. This allows lookbehinds to work when searching for multiple
2553    occurrences in a string.
2554    
2555    3. Added additional options to pcretest for testing multiple occurrences:
2556    
2557       /+   outputs the rest of the string that follows a match
2558       /g   loops for multiple occurrences, using the new startoffset argument
2559       /G   loops for multiple occurrences by passing an incremented pointer
2560    
2561    4. PCRE wasn't doing the "first character" optimization for patterns starting
2562    with \b or \B, though it was doing it for other lookbehind assertions. That is,
2563    it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2564    the letter 'x'. On long subject strings, this gives a significant speed-up.
2565    
2566    
2567  Version 2.05 21-Apr-99  Version 2.05 21-Apr-99
2568  ----------------------  ----------------------

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