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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 7.3 09-Aug-07
5    ---------------------
6    
7     1. In the rejigging of the build system that eventually resulted in 7.1, the
8        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
9        brackets there is not right, since it causes compilers to look for an
10        installed pcre.h, not the version that is in the source that is being
11        compiled (which of course may be different). I have changed it back to:
12    
13          #include "pcre.h"
14    
15        I have a vague recollection that the change was concerned with compiling in
16        different directories, but in the new build system, that is taken care of
17        by the VPATH setting the Makefile.
18    
19     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
20        when the subject happened to end in the byte 0x85 (e.g. if the last
21        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
22        characters but of course it shouldn't be taken as a newline when it is part
23        of another character. The bug was that, for an unlimited repeat of . in
24        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
25        characters when looking for a newline.
26    
27     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
28    
29     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
30        in debug output.
31    
32     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
33        long printing in the pcrecpp unittest when running under MinGW.
34    
35     6. ESC_K was left out of the EBCDIC table.
36    
37     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
38        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
39        limit also applies to "virtual nesting" when a pattern is recursive, and in
40        this case 1000 isn't so big. I have been able to remove this limit at the
41        expense of backing off one optimization in certain circumstances. Normally,
42        when pcre_exec() would call its internal match() function recursively and
43        immediately return the result unconditionally, it uses a "tail recursion"
44        feature to save stack. However, when a subpattern that can match an empty
45        string has an unlimited repetition quantifier, it no longer makes this
46        optimization. That gives it a stack frame in which to save the data for
47        checking that an empty string has been matched. Previously this was taken
48        from the 1000-entry workspace that had been reserved. So now there is no
49        explicit limit, but more stack is used.
50    
51     8. Applied Daniel's patches to solve problems with the import/export magic
52        syntax that is required for Windows, and which was going wrong for the
53        pcreposix and pcrecpp parts of the library. These were overlooked when this
54        problem was solved for the main library.
55    
56     9. There were some crude static tests to avoid integer overflow when computing
57        the size of patterns that contain repeated groups with explicit upper
58        limits. As the maximum quantifier is 65535, the maximum group length was
59        set at 30,000 so that the product of these two numbers did not overflow a
60        32-bit integer. However, it turns out that people want to use groups that
61        are longer than 30,000 bytes (though not repeat them that many times).
62        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
63        made it possible to implement the integer overflow checks in a much more
64        dynamic way, which I have now done. The artificial limitation on group
65        length has been removed - we now have only the limit on the total length of
66        the compiled pattern, which depends on the LINK_SIZE setting.
67    
68    10. Fixed a bug in the documentation for get/copy named substring when
69        duplicate names are permitted. If none of the named substrings are set, the
70        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
71        empty string.
72    
73    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
74        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
75        because the ] is interpreted as the first data character and the
76        terminating ] is not found. PCRE has been made compatible with Perl in this
77        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
78        cause memory overwriting.
79    
80    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
81        string has been matched (to stop an infinite loop). It was not recognizing
82        a conditional subpattern that could match an empty string if that
83        subpattern was within another subpattern. For example, it looped when
84        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
85        condition was not nested. This bug has been fixed.
86    
87    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
88        past the start of the subject in the presence of bytes with the top bit
89        set, for example "\x8aBCD".
90    
91    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
92        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
93    
94    14. Optimized (?!) to (*FAIL).
95    
96    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
97        This restricts code points to be within the range 0 to 0x10FFFF, excluding
98        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
99        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
100        does: it's just the validity check that is more restrictive.
101    
102    16. Inserted checks for integer overflows during escape sequence (backslash)
103        processing, and also fixed erroneous offset values for syntax errors during
104        backslash processing.
105    
106    
107    Version 7.2 19-Jun-07
108    ---------------------
109    
110     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
111        which is apparently normally available under Windows.
112    
113     2. Re-jig the pcregrep tests with different newline settings in an attempt
114        to make them independent of the local environment's newline setting.
115    
116     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
117    
118     4. Some of the "internals" tests were previously cut out when the link size
119        was not 2, because the output contained actual offsets. The recent new
120        "Z" feature of pcretest means that these can be cut out, making the tests
121        usable with all link sizes.
122    
123     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
124        stack recursion. This gives a massive performance boost under BSD, but just
125        a small improvement under Linux. However, it saves one field in the frame
126        in all cases.
127    
128     6. Added more features from the forthcoming Perl 5.10:
129    
130        (a) (?-n) (where n is a string of digits) is a relative subroutine or
131            recursion call. It refers to the nth most recently opened parentheses.
132    
133        (b) (?+n) is also a relative subroutine call; it refers to the nth next
134            to be opened parentheses.
135    
136        (c) Conditions that refer to capturing parentheses can be specified
137            relatively, for example, (?(-2)... or (?(+3)...
138    
139        (d) \K resets the start of the current match so that everything before
140            is not part of it.
141    
142        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
143    
144        (f) \g{name} is another synonym - part of Perl 5.10's unification of
145            reference syntax.
146    
147        (g) (?| introduces a group in which the numbering of parentheses in each
148            alternative starts with the same number.
149    
150        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
151    
152     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
153        PCRE_INFO_JCHANGED.
154    
155     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
156        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
157        for detecting groups that can match an empty string.
158    
159     9. A pattern with a very large number of alternatives (more than several
160        hundred) was running out of internal workspace during the pre-compile
161        phase, where pcre_compile() figures out how much memory will be needed. A
162        bit of new cunning has reduced the workspace needed for groups with
163        alternatives. The 1000-alternative test pattern now uses 12 bytes of
164        workspace instead of running out of the 4096 that are available.
165    
166    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
167    
168    11. Applied patch from Google to remove an optimization that didn't quite work.
169        The report of the bug said:
170    
171          pcrecpp::RE("a*").FullMatch("aaa") matches, while
172          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
173          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
174    
175    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
176        it matched the wrong number of bytes.
177    
178    
179    Version 7.1 24-Apr-07
180    ---------------------
181    
182     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
183        that is more "standard", making use of automake and other Autotools. There
184        is some re-arrangement of the files and adjustment of comments consequent
185        on this.
186    
187     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
188        for recursive directory scanning broke on some systems because the files
189        are not scanned in any specific order and on different systems the order
190        was different. A call to "sort" has been inserted into RunGrepTest for the
191        approprate test as a short-term fix. In the longer term there may be an
192        alternative.
193    
194     3. I had an email from Eric Raymond about problems translating some of PCRE's
195        man pages to HTML (despite the fact that I distribute HTML pages, some
196        people do their own conversions for various reasons). The problems
197        concerned the use of low-level troff macros .br and .in. I have therefore
198        removed all such uses from the man pages (some were redundant, some could
199        be replaced by .nf/.fi pairs). The 132html script that I use to generate
200        HTML has been updated to handle .nf/.fi and to complain if it encounters
201        .br or .in.
202    
203     4. Updated comments in configure.ac that get placed in config.h.in and also
204        arranged for config.h to be included in the distribution, with the name
205        config.h.generic, for the benefit of those who have to compile without
206        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
207    
208     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
209        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
210        makevp.bat for the current PCRE, using the additional files
211        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
212    
213     6. A Windows user reported a minor discrepancy with test 2, which turned out
214        to be caused by a trailing space on an input line that had got lost in his
215        copy. The trailing space was an accident, so I've just removed it.
216    
217     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
218        that is needed.
219    
220     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
221        as "const" (a) because they are and (b) because it helps the PHP
222        maintainers who have recently made a script to detect big data structures
223        in the php code that should be moved to the .rodata section. I remembered
224        to update Builducptable as well, so it won't revert if ucptable.h is ever
225        re-created.
226    
227     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
228        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
229        order to be able to cut out the UTF-8 tables in the latter when UTF-8
230        support is not required. This saves 1.5-2K of code, which is important in
231        some applications.
232    
233        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
234        so as not to refer to the tables, even though these functions will never be
235        called when UTF-8 support is disabled. Otherwise there are problems with a
236        shared library.
237    
238    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
239    
240        (a) It was defining its arguments as char * instead of void *.
241    
242        (b) It was assuming that all moves were upwards in memory; this was true
243            a long time ago when I wrote it, but is no longer the case.
244    
245        The emulated memove() is provided for those environments that have neither
246        memmove() nor bcopy(). I didn't think anyone used it these days, but that
247        is clearly not the case, as these two bugs were recently reported.
248    
249    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
250        and Detrail to create the HTML documentation, the .txt form of the man
251        pages, and it removes trailing spaces from listed files. It also creates
252        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
253        case, it wraps all the #defines with #ifndefs. This script should be run
254        before "make dist".
255    
256    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
257        with Unicode property support.
258    
259        (a) For a maximizing quantifier, if the two different cases of the
260            character were of different lengths in their UTF-8 codings (there are
261            some cases like this - I found 11), and the matching function had to
262            back up over a mixture of the two cases, it incorrectly assumed they
263            were both the same length.
264    
265        (b) When PCRE was configured to use the heap rather than the stack for
266            recursion during matching, it was not correctly preserving the data for
267            the other case of a UTF-8 character when checking ahead for a match
268            while processing a minimizing repeat. If the check also involved
269            matching a wide character, but failed, corruption could cause an
270            erroneous result when trying to check for a repeat of the original
271            character.
272    
273    13. Some tidying changes to the testing mechanism:
274    
275        (a) The RunTest script now detects the internal link size and whether there
276            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
277            values substituted by "configure". (The RunGrepTest script already did
278            this for UTF-8.) The configure.ac script no longer substitutes the
279            relevant variables.
280    
281        (b) The debugging options /B and /D in pcretest show the compiled bytecode
282            with length and offset values. This means that the output is different
283            for different internal link sizes. Test 2 is skipped for link sizes
284            other than 2 because of this, bypassing the problem. Unfortunately,
285            there was also a test in test 3 (the locale tests) that used /B and
286            failed for link sizes other than 2. Rather than cut the whole test out,
287            I have added a new /Z option to pcretest that replaces the length and
288            offset values with spaces. This is now used to make test 3 independent
289            of link size. (Test 2 will be tidied up later.)
290    
291    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
292        segmentation fault instead of returning the appropriate error message.
293    
294    15. In multiline mode when the newline sequence was set to "any", the pattern
295        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
296        This doesn't seem right; it now treats the CRLF combination as the line
297        ending, and so does not match in that case. It's only a pattern such as ^$
298        that would hit this one: something like ^ABC$ would have failed after \r
299        and then tried again after \r\n.
300    
301    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
302        in an attempt to make files that differ only in their line terminators
303        compare equal. This works on Linux.
304    
305    17. Under certain error circumstances pcregrep might try to free random memory
306        as it exited. This is now fixed, thanks to valgrind.
307    
308    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
309        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
310        was because its rules for how to advance for /g after matching an empty
311        string at the end of a line did not allow for this case. They now check for
312        it specially.
313    
314    20. pcretest is supposed to handle patterns and data of any length, by
315        extending its buffers when necessary. It was getting this wrong when the
316        buffer for a data line had to be extended.
317    
318    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
319        CRLF as a newline sequence.
320    
321    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
322        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
323        I have nevertheless tidied it up.
324    
325    23. Added some casts to kill warnings from HP-UX ia64 compiler.
326    
327    24. Added a man page for pcre-config.
328    
329    
330    Version 7.0 19-Dec-06
331    ---------------------
332    
333     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
334        moving to gcc 4.1.1.
335    
336     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
337        sys/time.h, which is documented as needed for this function. It doesn't
338        seem to matter on Linux, but it showed up on some releases of OS X.
339    
340     3. It seems that there are systems where bytes whose values are greater than
341        127 match isprint() in the "C" locale. The "C" locale should be the
342        default when a C program starts up. In most systems, only ASCII printing
343        characters match isprint(). This difference caused the output from pcretest
344        to vary, making some of the tests fail. I have changed pcretest so that:
345    
346        (a) When it is outputting text in the compiled version of a pattern, bytes
347            other than 32-126 are always shown as hex escapes.
348    
349        (b) When it is outputting text that is a matched part of a subject string,
350            it does the same, unless a different locale has been set for the match
351            (using the /L modifier). In this case, it uses isprint() to decide.
352    
353     4. Fixed a major bug that caused incorrect computation of the amount of memory
354        required for a compiled pattern when options that changed within the
355        pattern affected the logic of the preliminary scan that determines the
356        length. The relevant options are -x, and -i in UTF-8 mode. The result was
357        that the computed length was too small. The symptoms of this bug were
358        either the PCRE error "internal error: code overflow" from pcre_compile(),
359        or a glibc crash with a message such as "pcretest: free(): invalid next
360        size (fast)". Examples of patterns that provoked this bug (shown in
361        pcretest format) are:
362    
363          /(?-x: )/x
364          /(?x)(?-x: \s*#\s*)/
365          /((?i)[\x{c0}])/8
366          /(?i:[\x{c0}])/8
367    
368        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
369        is now done differently.
370    
371     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
372        wrapper classes; (b) implement a new function in the C++ scanner that is
373        more efficient than the old way of doing things because it avoids levels of
374        recursion in the regex matching; (c) add a paragraph to the documentation
375        for the FullMatch() function.
376    
377     6. The escape sequence \n was being treated as whatever was defined as
378        "newline". Not only was this contrary to the documentation, which states
379        that \n is character 10 (hex 0A), but it also went horribly wrong when
380        "newline" was defined as CRLF. This has been fixed.
381    
382     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
383        was being set to -1 for the "end of line" case (supposedly a value that no
384        character can have). Though this value is never used (the check for end of
385        line is "zero bytes in current character"), it caused compiler complaints.
386        I've changed it to 0xffffffff.
387    
388     8. In pcre_version.c, the version string was being built by a sequence of
389        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
390        string (as it is for production releases) called a macro with an empty
391        argument. The C standard says the result of this is undefined. The gcc
392        compiler treats it as an empty string (which was what was wanted) but it is
393        reported that Visual C gives an error. The source has been hacked around to
394        avoid this problem.
395    
396     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
397        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
398        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
399        of them did).
400    
401    10. Originally, pcretest opened its input and output without "b"; then I was
402        told that "b" was needed in some environments, so it was added for release
403        5.0 to both the input and output. (It makes no difference on Unix-like
404        systems.) Later I was told that it is wrong for the input on Windows. I've
405        now abstracted the modes into two macros, to make it easier to fiddle with
406        them, and removed "b" from the input mode under Windows.
407    
408    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
409    
410    12. Added -help and --help to pcretest as an official way of being reminded
411        of the options.
412    
413    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
414        and pcrecpp.cc because they annoy compilers at high warning levels.
415    
416    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
417    
418    15. Fixed an occurrence of == in configure.ac that should have been = (shell
419        scripts are not C programs :-) and which was not noticed because it works
420        on Linux.
421    
422    16. pcretest is supposed to handle any length of pattern and data line (as one
423        line or as a continued sequence of lines) by extending its input buffer if
424        necessary. This feature was broken for very long pattern lines, leading to
425        a string of junk being passed to pcre_compile() if the pattern was longer
426        than about 50K.
427    
428    17. I have done a major re-factoring of the way pcre_compile() computes the
429        amount of memory needed for a compiled pattern. Previously, there was code
430        that made a preliminary scan of the pattern in order to do this. That was
431        OK when PCRE was new, but as the facilities have expanded, it has become
432        harder and harder to keep it in step with the real compile phase, and there
433        have been a number of bugs (see for example, 4 above). I have now found a
434        cunning way of running the real compile function in a "fake" mode that
435        enables it to compute how much memory it would need, while actually only
436        ever using a few hundred bytes of working memory and without too many
437        tests of the mode. This should make future maintenance and development
438        easier. A side effect of this work is that the limit of 200 on the nesting
439        depth of parentheses has been removed (though this was never a serious
440        limitation, I suspect). However, there is a downside: pcre_compile() now
441        runs more slowly than before (30% or more, depending on the pattern). I
442        hope this isn't a big issue. There is no effect on runtime performance.
443    
444    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
445        newline (only possible for the last line of a file) and it was a
446        pattern that set a locale (followed by /Lsomething), pcretest crashed.
447    
448    19. Added additional timing features to pcretest. (1) The -tm option now times
449        matching only, not compiling. (2) Both -t and -tm can be followed, as a
450        separate command line item, by a number that specifies the number of
451        repeats to use when timing. The default is 50000; this gives better
452        precision, but takes uncomfortably long for very large patterns.
453    
454    20. Extended pcre_study() to be more clever in cases where a branch of a
455        subpattern has no definite first character. For example, (a*|b*)[cd] would
456        previously give no result from pcre_study(). Now it recognizes that the
457        first character must be a, b, c, or d.
458    
459    21. There was an incorrect error "recursive call could loop indefinitely" if
460        a subpattern (or the entire pattern) that was being tested for matching an
461        empty string contained only one non-empty item after a nested subpattern.
462        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
463        incorrectly, because the \d was being skipped in the check.
464    
465    22. The pcretest program now has a new pattern option /B and a command line
466        option -b, which is equivalent to adding /B to every pattern. This causes
467        it to show the compiled bytecode, without the additional information that
468        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
469        is the same as /B/I).
470    
471    23. A new optimization is now able automatically to treat some sequences such
472        as a*b as a*+b. More specifically, if something simple (such as a character
473        or a simple class like \d) has an unlimited quantifier, and is followed by
474        something that cannot possibly match the quantified thing, the quantifier
475        is automatically "possessified".
476    
477    24. A recursive reference to a subpattern whose number was greater than 39
478        went wrong under certain circumstances in UTF-8 mode. This bug could also
479        have affected the operation of pcre_study().
480    
481    25. Realized that a little bit of performance could be had by replacing
482        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
483    
484    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
485    
486    27. Possessive quantifiers such as a++ were previously implemented by turning
487        them into atomic groups such as ($>a+). Now they have their own opcodes,
488        which improves performance. This includes the automatically created ones
489        from 23 above.
490    
491    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
492        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
493        the first matched character to be a colon. This applied both to named and
494        numbered groups.
495    
496    29. The ucpinternal.h header file was missing its idempotency #ifdef.
497    
498    30. I was sent a "project" file called libpcre.a.dev which I understand makes
499        building PCRE on Windows easier, so I have included it in the distribution.
500    
501    31. There is now a check in pcretest against a ridiculously large number being
502        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
503        loop, the loop is abandoned.
504    
505    32. Forward references to subpatterns in conditions such as (?(2)...) where
506        subpattern 2 is defined later cause pcre_compile() to search forwards in
507        the pattern for the relevant set of parentheses. This search went wrong
508        when there were unescaped parentheses in a character class, parentheses
509        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
510    
511    33. "Subroutine" calls and backreferences were previously restricted to
512        referencing subpatterns earlier in the regex. This restriction has now
513        been removed.
514    
515    34. Added a number of extra features that are going to be in Perl 5.10. On the
516        whole, these are just syntactic alternatives for features that PCRE had
517        previously implemented using the Python syntax or my own invention. The
518        other formats are all retained for compatibility.
519    
520        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
521            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
522            also .NET compatible.
523    
524        (b) A recursion or subroutine call to a named group can now be defined as
525            (?&name) as well as (?P>name).
526    
527        (c) A backreference to a named group can now be defined as \k<name> or
528            \k'name' as well as (?P=name). The new forms, as well as being in Perl
529            5.10, are also .NET compatible.
530    
531        (d) A conditional reference to a named group can now use the syntax
532            (?(<name>) or (?('name') as well as (?(name).
533    
534        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
535            groups (named and numbered) that are never evaluated inline, but can be
536            called as "subroutines" from elsewhere. In effect, the DEFINE condition
537            is always false. There may be only one alternative in such a group.
538    
539        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
540            as the simple (?(R). The condition is true only if the most recent
541            recursion is that of the given number or name. It does not search out
542            through the entire recursion stack.
543    
544        (g) The escape \gN or \g{N} has been added, where N is a positive or
545            negative number, specifying an absolute or relative reference.
546    
547    35. Tidied to get rid of some further signed/unsigned compiler warnings and
548        some "unreachable code" warnings.
549    
550    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
551        things, this adds five new scripts.
552    
553    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
554        There were also incompatibilities regarding the handling of \Q..\E inside
555        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
556        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
557    
558    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
559        matches an empty string, and forcibly breaks the loop. There were bugs in
560        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
561        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
562        separate and independent bugs (that affected different cases) have been
563        fixed.
564    
565    39. Refactored the code to abolish the use of different opcodes for small
566        capturing bracket numbers. This is a tidy that I avoided doing when I
567        removed the limit on the number of capturing brackets for 3.5 back in 2001.
568        The new approach is not only tidier, it makes it possible to reduce the
569        memory needed to fix the previous bug (38).
570    
571    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
572        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
573        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
574        mode.
575    
576    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
577        report.
578    
579    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
580        copy construction and assignment in the C++ wrapper.
581    
582    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
583        couple of bugs that could have given wrong results in the "--newline=crlf"
584        case.
585    
586    44. Added a number of casts and did some reorganization of signed/unsigned int
587        variables following suggestions from Dair Grant. Also renamed the variable
588        "this" as "item" because it is a C++ keyword.
589    
590    45. Arranged for dftables to add
591    
592          #include "pcre_internal.h"
593    
594        to pcre_chartables.c because without it, gcc 4.x may remove the array
595        definition from the final binary if PCRE is built into a static library and
596        dead code stripping is activated.
597    
598    46. For an unanchored pattern, if a match attempt fails at the start of a
599        newline sequence, and the newline setting is CRLF or ANY, and the next two
600        characters are CRLF, advance by two characters instead of one.
601    
602    
603    Version 6.7 04-Jul-06
604    ---------------------
605    
606     1. In order to handle tests when input lines are enormously long, pcretest has
607        been re-factored so that it automatically extends its buffers when
608        necessary. The code is crude, but this _is_ just a test program. The
609        default size has been increased from 32K to 50K.
610    
611     2. The code in pcre_study() was using the value of the re argument before
612        testing it for NULL. (Of course, in any sensible call of the function, it
613        won't be NULL.)
614    
615     3. The memmove() emulation function in pcre_internal.h, which is used on
616        systems that lack both memmove() and bcopy() - that is, hardly ever -
617        was missing a "static" storage class specifier.
618    
619     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
620        containing an extended class (one that cannot be represented by a bitmap
621        because it contains high-valued characters or Unicode property items, e.g.
622        [\pZ]). Almost always one would set UTF-8 mode when processing such a
623        pattern, but PCRE should not loop if you do not (it no longer does).
624        [Detail: two cases were found: (a) a repeated subpattern containing an
625        extended class; (b) a recursive reference to a subpattern that followed a
626        previous extended class. It wasn't skipping over the extended class
627        correctly when UTF-8 mode was not set.]
628    
629     5. A negated single-character class was not being recognized as fixed-length
630        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
631        compile error "lookbehind assertion is not fixed length".
632    
633     6. The RunPerlTest auxiliary script was showing an unexpected difference
634        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
635        write a Perl script that can interpret lines of an input file either as
636        byte characters or as UTF-8, which is what "perltest" was being required to
637        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
638        can't do is switch easily at run time between having the "use utf8;" pragma
639        or not. In the end, I fudged it by using the RunPerlTest script to insert
640        "use utf8;" explicitly for the UTF-8 tests.
641    
642     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
643        the end of the subject string, contrary to the documentation and to what
644        Perl does. This was true of both matching functions. Now it matches only at
645        the start of the subject and immediately after *internal* newlines.
646    
647     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
648        a pointer to an int instead of a pointer to an unsigned long int. This
649        caused problems on 64-bit systems.
650    
651     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
652        instance of the 'standard' template library not being so standard".
653    
654    10. There was no check on the number of named subpatterns nor the maximum
655        length of a subpattern name. The product of these values is used to compute
656        the size of the memory block for a compiled pattern. By supplying a very
657        long subpattern name and a large number of named subpatterns, the size
658        computation could be caused to overflow. This is now prevented by limiting
659        the length of names to 32 characters, and the number of named subpatterns
660        to 10,000.
661    
662    11. Subpatterns that are repeated with specific counts have to be replicated in
663        the compiled pattern. The size of memory for this was computed from the
664        length of the subpattern and the repeat count. The latter is limited to
665        65535, but there was no limit on the former, meaning that integer overflow
666        could in principle occur. The compiled length of a repeated subpattern is
667        now limited to 30,000 bytes in order to prevent this.
668    
669    12. Added the optional facility to have named substrings with the same name.
670    
671    13. Added the ability to use a named substring as a condition, using the
672        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
673        are numbers (not recommended). Forward references are permitted.
674    
675    14. Added forward references in named backreferences (if you see what I mean).
676    
677    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
678        pattern could run off the end of the subject. For example, the pattern
679        "(?s)(.{1,5})"8 did this with the subject "ab".
680    
681    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
682        PCRE_CASELESS was set when matching characters that were quantified with ?
683        or *.
684    
685    17. A character class other than a single negated character that had a minimum
686        but no maximum quantifier - for example [ab]{6,} - was not handled
687        correctly by pce_dfa_exec(). It would match only one character.
688    
689    18. A valid (though odd) pattern that looked like a POSIX character
690        class but used an invalid character after [ (for example [[,abc,]]) caused
691        pcre_compile() to give the error "Failed: internal error: code overflow" or
692        in some cases to crash with a glibc free() error. This could even happen if
693        the pattern terminated after [[ but there just happened to be a sequence of
694        letters, a binary zero, and a closing ] in the memory that followed.
695    
696    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
697        over the years. Originally (before any Unicode support), just the bottom 8
698        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
699        output from "man perlunicode" includes this:
700    
701          The regular expression compiler produces polymorphic opcodes.  That
702          is, the pattern adapts to the data and automatically switches to
703          the Unicode character scheme when presented with Unicode data--or
704          instead uses a traditional byte scheme when presented with byte
705          data.
706    
707        Sadly, a wide octal escape does not cause a switch, and in a string with
708        no other multibyte characters, these octal escapes are treated as before.
709        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
710        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
711        Unicode string.
712    
713        I have not perpetrated such confusion in PCRE. Up till now, it took just
714        the bottom 8 bits, as in old Perl. I have now made octal escapes with
715        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
716        translate to the appropriate multibyte character.
717    
718    29. Applied some refactoring to reduce the number of warnings from Microsoft
719        and Borland compilers. This has included removing the fudge introduced
720        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
721        a warning about an unused variable.
722    
723    21. PCRE has not included VT (character 0x0b) in the set of whitespace
724        characters since release 4.0, because Perl (from release 5.004) does not.
725        [Or at least, is documented not to: some releases seem to be in conflict
726        with the documentation.] However, when a pattern was studied with
727        pcre_study() and all its branches started with \s, PCRE still included VT
728        as a possible starting character. Of course, this did no harm; it just
729        caused an unnecessary match attempt.
730    
731    22. Removed a now-redundant internal flag bit that recorded the fact that case
732        dependency changed within the pattern. This was once needed for "required
733        byte" processing, but is no longer used. This recovers a now-scarce options
734        bit. Also moved the least significant internal flag bit to the most-
735        significant bit of the word, which was not previously used (hangover from
736        the days when it was an int rather than a uint) to free up another bit for
737        the future.
738    
739    23. Added support for CRLF line endings as well as CR and LF. As well as the
740        default being selectable at build time, it can now be changed at runtime
741        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
742        specify that it is scanning data with non-default line endings.
743    
744    24. Changed the definition of CXXLINK to make it agree with the definition of
745        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
746    
747    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
748        recursions. This makes a big different to stack usage for some patterns.
749    
750    26. If a subpattern containing a named recursion or subroutine reference such
751        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
752        the space required for the compiled pattern went wrong and gave too small a
753        value. Depending on the environment, this could lead to "Failed: internal
754        error: code overflow at offset 49" or "glibc detected double free or
755        corruption" errors.
756    
757    27. Applied patches from Google (a) to support the new newline modes and (b) to
758        advance over multibyte UTF-8 characters in GlobalReplace.
759    
760    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
761        difference for some implementation of PCRE in some Windows version.
762    
763    29. Added some extra testing facilities to pcretest:
764    
765        \q<number>   in a data line sets the "match limit" value
766        \Q<number>   in a data line sets the "match recursion limt" value
767        -S <number>  sets the stack size, where <number> is in megabytes
768    
769        The -S option isn't available for Windows.
770    
771    
772    Version 6.6 06-Feb-06
773    ---------------------
774    
775     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
776        in pcreposix.h. I have copied the definition from pcre.h.
777    
778     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
779        because pcre.h is no longer a built file.
780    
781     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
782        not normally included in the compiled code.
783    
784    
785    Version 6.5 01-Feb-06
786    ---------------------
787    
788     1. When using the partial match feature with pcre_dfa_exec(), it was not
789        anchoring the second and subsequent partial matches at the new starting
790        point. This could lead to incorrect results. For example, with the pattern
791        /1234/, partially matching against "123" and then "a4" gave a match.
792    
793     2. Changes to pcregrep:
794    
795        (a) All non-match returns from pcre_exec() were being treated as failures
796            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
797            error message is output. Some extra information is given for the
798            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
799            probably the only errors that are likely to be caused by users (by
800            specifying a regex that has nested indefinite repeats, for instance).
801            If there are more than 20 of these errors, pcregrep is abandoned.
802    
803        (b) A binary zero was treated as data while matching, but terminated the
804            output line if it was written out. This has been fixed: binary zeroes
805            are now no different to any other data bytes.
806    
807        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
808            used to set a locale for matching. The --locale=xxxx long option has
809            been added (no short equivalent) to specify a locale explicitly on the
810            pcregrep command, overriding the environment variables.
811    
812        (d) When -B was used with -n, some line numbers in the output were one less
813            than they should have been.
814    
815        (e) Added the -o (--only-matching) option.
816    
817        (f) If -A or -C was used with -c (count only), some lines of context were
818            accidentally printed for the final match.
819    
820        (g) Added the -H (--with-filename) option.
821    
822        (h) The combination of options -rh failed to suppress file names for files
823            that were found from directory arguments.
824    
825        (i) Added the -D (--devices) and -d (--directories) options.
826    
827        (j) Added the -F (--fixed-strings) option.
828    
829        (k) Allow "-" to be used as a file name for -f as well as for a data file.
830    
831        (l) Added the --colo(u)r option.
832    
833        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
834            is not present by default.
835    
836     3. A nasty bug was discovered in the handling of recursive patterns, that is,
837        items such as (?R) or (?1), when the recursion could match a number of
838        alternatives. If it matched one of the alternatives, but subsequently,
839        outside the recursion, there was a failure, the code tried to back up into
840        the recursion. However, because of the way PCRE is implemented, this is not
841        possible, and the result was an incorrect result from the match.
842    
843        In order to prevent this happening, the specification of recursion has
844        been changed so that all such subpatterns are automatically treated as
845        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
846    
847     4. I had overlooked the fact that, in some locales, there are characters for
848        which isalpha() is true but neither isupper() nor islower() are true. In
849        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
850        and ordfeminine) are like this. This affected the treatment of \w and \W
851        when they appeared in character classes, but not when they appeared outside
852        a character class. The bit map for "word" characters is now created
853        separately from the results of isalnum() instead of just taking it from the
854        upper, lower, and digit maps. (Plus the underscore character, of course.)
855    
856     5. The above bug also affected the handling of POSIX character classes such as
857        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
858        permanent tables. Instead, the bit maps for such a class were previously
859        created as the appropriate unions of the upper, lower, and digit bitmaps.
860        Now they are created by subtraction from the [[:word:]] class, which has
861        its own bitmap.
862    
863     6. The [[:blank:]] character class matches horizontal, but not vertical space.
864        It is created by subtracting the vertical space characters (\x09, \x0a,
865        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
866        subtraction was done in the overall bitmap for a character class, meaning
867        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
868        be recognized. This bug has been fixed.
869    
870     7. Patches from the folks at Google:
871    
872          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
873          real life, but is still worth protecting against".
874    
875          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
876          regular expressions".
877    
878          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
879          have it.
880    
881          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
882          "configure" and the latter not, in order to fix a problem somebody had
883          with compiling the Arg class on HP-UX.
884    
885          (e) Improve the error-handling of the C++ wrapper a little bit.
886    
887          (f) New tests for checking recursion limiting.
888    
889     8. The pcre_memmove() function, which is used only if the environment does not
890        have a standard memmove() function (and is therefore rarely compiled),
891        contained two bugs: (a) use of int instead of size_t, and (b) it was not
892        returning a result (though PCRE never actually uses the result).
893    
894     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
895        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
896        returned instead of calling malloc() with an overflowing number that would
897        most likely cause subsequent chaos.
898    
899    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
900    
901    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
902        with this option is matched, the nmatch and pmatch options of regexec() are
903        ignored.
904    
905    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
906        provided in case anyone wants to the the POSIX interface with UTF-8
907        strings.
908    
909    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
910        C++ linking (needed for some HP-UX environments).
911    
912    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
913        (unused parameter) and in the pcre_printint() function (omitted "default"
914        switch label when the default is to do nothing).
915    
916    15. Added some code to make it possible, when PCRE is compiled as a C++
917        library, to replace subject pointers for pcre_exec() with a smart pointer
918        class, thus making it possible to process discontinuous strings.
919    
920    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
921        much the same function. They were added by different people who were trying
922        to make PCRE easy to compile on non-Unix systems. It has been suggested
923        that PCRE_EXPORT be abolished now that there is more automatic apparatus
924        for compiling on Windows systems. I have therefore replaced it with
925        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
926        defaults to "extern" for C or "extern C" for C++, which works fine on
927        Unix-like systems. It is now possible to override the value of PCRE_DATA_
928        SCOPE with something explicit in config.h. In addition:
929    
930        (a) pcreposix.h still had just "extern" instead of either of these macros;
931            I have replaced it with PCRE_DATA_SCOPE.
932    
933        (b) Functions such as _pcre_xclass(), which are internal to the library,
934            but external in the C sense, all had PCRE_EXPORT in their definitions.
935            This is apparently wrong for the Windows case, so I have removed it.
936            (It makes no difference on Unix-like systems.)
937    
938    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
939        of recursive calls to match(). This is different to MATCH_LIMIT because
940        that limits the total number of calls to match(), not all of which increase
941        the depth of recursion. Limiting the recursion depth limits the amount of
942        stack (or heap if NO_RECURSE is set) that is used. The default can be set
943        when PCRE is compiled, and changed at run time. A patch from Google adds
944        this functionality to the C++ interface.
945    
946    18. Changes to the handling of Unicode character properties:
947    
948        (a) Updated the table to Unicode 4.1.0.
949    
950        (b) Recognize characters that are not in the table as "Cn" (undefined).
951    
952        (c) I revised the way the table is implemented to a much improved format
953            which includes recognition of ranges. It now supports the ranges that
954            are defined in UnicodeData.txt, and it also amalgamates other
955            characters into ranges. This has reduced the number of entries in the
956            table from around 16,000 to around 3,000, thus reducing its size
957            considerably. I realized I did not need to use a tree structure after
958            all - a binary chop search is just as efficient. Having reduced the
959            number of entries, I extended their size from 6 bytes to 8 bytes to
960            allow for more data.
961    
962        (d) Added support for Unicode script names via properties such as \p{Han}.
963    
964    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
965        matching that character.
966    
967    20. When matching a repeated Unicode property with a minimum greater than zero,
968        (for example \pL{2,}), PCRE could look past the end of the subject if it
969        reached it while seeking the minimum number of characters. This could
970        happen only if some of the characters were more than one byte long, because
971        there is a check for at least the minimum number of bytes.
972    
973    21. Refactored the implementation of \p and \P so as to be more general, to
974        allow for more different types of property in future. This has changed the
975        compiled form incompatibly. Anybody with saved compiled patterns that use
976        \p or \P will have to recompile them.
977    
978    22. Added "Any" and "L&" to the supported property types.
979    
980    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
981        but give a compile time error if the value is greater than 0xff.
982    
983    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
984        accidentally not being installed or uninstalled.
985    
986    25. The pcre.h file was built from pcre.h.in, but the only changes that were
987        made were to insert the current release number. This seemed silly, because
988        it made things harder for people building PCRE on systems that don't run
989        "configure". I have turned pcre.h into a distributed file, no longer built
990        by "configure", with the version identification directly included. There is
991        no longer a pcre.h.in file.
992    
993        However, this change necessitated a change to the pcre-config script as
994        well. It is built from pcre-config.in, and one of the substitutions was the
995        release number. I have updated configure.ac so that ./configure now finds
996        the release number by grepping pcre.h.
997    
998    26. Added the ability to run the tests under valgrind.
999    
1000    
1001    Version 6.4 05-Sep-05
1002    ---------------------
1003    
1004     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1005        "--" to be printed when multiple files were scanned, even when none of the
1006        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1007        consider it to be a bug, and have restored the previous behaviour.
1008    
1009     2. A couple of code tidies to get rid of compiler warnings.
1010    
1011     3. The pcretest program used to cheat by referring to symbols in the library
1012        whose names begin with _pcre_. These are internal symbols that are not
1013        really supposed to be visible externally, and in some environments it is
1014        possible to suppress them. The cheating is now confined to including
1015        certain files from the library's source, which is a bit cleaner.
1016    
1017     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1018        file's purpose clearer.
1019    
1020     5. Reorganized pcre_ucp_findchar().
1021    
1022    
1023    Version 6.3 15-Aug-05
1024    ---------------------
1025    
1026     1. The file libpcre.pc.in did not have general read permission in the tarball.
1027    
1028     2. There were some problems when building without C++ support:
1029    
1030        (a) If C++ support was not built, "make install" and "make test" still
1031            tried to test it.
1032    
1033        (b) There were problems when the value of CXX was explicitly set. Some
1034            changes have been made to try to fix these, and ...
1035    
1036        (c) --disable-cpp can now be used to explicitly disable C++ support.
1037    
1038        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1039            backslash in a target when C++ was disabled. This confuses some
1040            versions of "make", apparently. Using an intermediate variable solves
1041            this. (Same for CPP_LOBJ.)
1042    
1043     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1044        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1045        necessary on certain architectures.
1046    
1047     4. Added a setting of -export-symbols-regex to the link command to remove
1048        those symbols that are exported in the C sense, but actually are local
1049        within the library, and not documented. Their names all begin with
1050        "_pcre_". This is not a perfect job, because (a) we have to except some
1051        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1052        available (and never for static libraries). I have made a note to try to
1053        find a way round (a) in the future.
1054    
1055    
1056    Version 6.2 01-Aug-05
1057    ---------------------
1058    
1059     1. There was no test for integer overflow of quantifier values. A construction
1060        such as {1111111111111111} would give undefined results. What is worse, if
1061        a minimum quantifier for a parenthesized subpattern overflowed and became
1062        negative, the calculation of the memory size went wrong. This could have
1063        led to memory overwriting.
1064    
1065     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1066    
1067     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1068        operating environments where this matters.
1069    
1070     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1071        PCRE options from within the C++ wrapper.
1072    
1073     5. Named capturing subpatterns were not being correctly counted when a pattern
1074        was compiled. This caused two problems: (a) If there were more than 100
1075        such subpatterns, the calculation of the memory needed for the whole
1076        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1077        back references of the form \12, where the number was greater than 9, were
1078        not recognized as back references, even though there were sufficient
1079        previous subpatterns.
1080    
1081     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1082        versions of gcc, e.g. 2.95.4.
1083    
1084    
1085    Version 6.1 21-Jun-05
1086    ---------------------
1087    
1088     1. There was one reference to the variable "posix" in pcretest.c that was not
1089        surrounded by "#if !defined NOPOSIX".
1090    
1091     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1092        the cross-check on the old pcre_info() function, for the benefit of the
1093        cut-down version of PCRE that is currently imported into Exim.
1094    
1095     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1096        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1097        patterns that start (?i) but I don't think that matters. The use of (?i) is
1098        just an example; this all applies to the other options as well.
1099    
1100     4. Since libtool seems to echo the compile commands it is issuing, the output
1101        from "make" can be reduced a bit by putting "@" in front of each libtool
1102        compile command.
1103    
1104     5. Patch from the folks at Google for configure.in to be a bit more thorough
1105        in checking for a suitable C++ installation before trying to compile the
1106        C++ stuff. This should fix a reported problem when a compiler was present,
1107        but no suitable headers.
1108    
1109     6. The man pages all had just "PCRE" as their title. I have changed them to
1110        be the relevant file name. I have also arranged that these names are
1111        retained in the file doc/pcre.txt, which is a concatenation in text format
1112        of all the man pages except the little individual ones for each function.
1113    
1114     7. The NON-UNIX-USE file had not been updated for the different set of source
1115        files that come with release 6. I also added a few comments about the C++
1116        wrapper.
1117    
1118    
1119    Version 6.0 07-Jun-05
1120    ---------------------
1121    
1122     1. Some minor internal re-organization to help with my DFA experiments.
1123    
1124     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1125        didn't matter for the library itself when fully configured, but did matter
1126        when compiling without UCP support, or within Exim, where the ucp files are
1127        not imported.
1128    
1129     3. Refactoring of the library code to split up the various functions into
1130        different source modules. The addition of the new DFA matching code (see
1131        below) to a single monolithic source would have made it really too
1132        unwieldy, quite apart from causing all the code to be include in a
1133        statically linked application, when only some functions are used. This is
1134        relevant even without the DFA addition now that patterns can be compiled in
1135        one application and matched in another.
1136    
1137        The downside of splitting up is that there have to be some external
1138        functions and data tables that are used internally in different modules of
1139        the library but which are not part of the API. These have all had their
1140        names changed to start with "_pcre_" so that they are unlikely to clash
1141        with other external names.
1142    
1143     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1144        a different (DFA) algorithm. Although it is slower than the original
1145        function, it does have some advantages for certain types of matching
1146        problem.
1147    
1148     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1149        including restarting after a partial match.
1150    
1151     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1152        defined when compiling for Windows was sent to me. I have put it into the
1153        code, though I have no means of testing or verifying it.
1154    
1155     7. Added the pcre_refcount() auxiliary function.
1156    
1157     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1158        match before or at the first newline in the subject string. In pcretest,
1159        the /f option on a pattern can be used to set this.
1160    
1161     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1162        would behave wrongly. This has been present in PCRE since release 4.0.
1163    
1164    10. A number of changes to the pcregrep command:
1165    
1166        (a) Refactored how -x works; insert ^(...)$ instead of setting
1167            PCRE_ANCHORED and checking the length, in preparation for adding
1168            something similar for -w.
1169    
1170        (b) Added the -w (match as a word) option.
1171    
1172        (c) Refactored the way lines are read and buffered so as to have more
1173            than one at a time available.
1174    
1175        (d) Implemented a pcregrep test script.
1176    
1177        (e) Added the -M (multiline match) option. This allows patterns to match
1178            over several lines of the subject. The buffering ensures that at least
1179            8K, or the rest of the document (whichever is the shorter) is available
1180            for matching (and similarly the previous 8K for lookbehind assertions).
1181    
1182        (f) Changed the --help output so that it now says
1183    
1184              -w, --word-regex(p)
1185    
1186            instead of two lines, one with "regex" and the other with "regexp"
1187            because that confused at least one person since the short forms are the
1188            same. (This required a bit of code, as the output is generated
1189            automatically from a table. It wasn't just a text change.)
1190    
1191        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1192            option but starts with a hyphen. Could be a pattern or a path name
1193            starting with a hyphen, for instance.
1194    
1195        (h) "-" can be given as a file name to represent stdin.
1196    
1197        (i) When file names are being printed, "(standard input)" is used for
1198            the standard input, for compatibility with GNU grep. Previously
1199            "<stdin>" was used.
1200    
1201        (j) The option --label=xxx can be used to supply a name to be used for
1202            stdin when file names are being printed. There is no short form.
1203    
1204        (k) Re-factored the options decoding logic because we are going to add
1205            two more options that take data. Such options can now be given in four
1206            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1207    
1208        (l) Added the -A, -B, and -C options for requesting that lines of context
1209            around matches be printed.
1210    
1211        (m) Added the -L option to print the names of files that do not contain
1212            any matching lines, that is, the complement of -l.
1213    
1214        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1215            continue to scan other files.
1216    
1217        (o) The -s option was incorrectly implemented. For compatibility with other
1218            greps, it now suppresses the error message for a non-existent or non-
1219            accessible file (but not the return code). There is a new option called
1220            -q that suppresses the output of matching lines, which was what -s was
1221            previously doing.
1222    
1223        (p) Added --include and --exclude options to specify files for inclusion
1224            and exclusion when recursing.
1225    
1226    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1227        Hopefully, it now does.
1228    
1229    12. Missing cast in pcre_study().
1230    
1231    13. Added an "uninstall" target to the makefile.
1232    
1233    14. Replaced "extern" in the function prototypes in Makefile.in with
1234        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1235        world, but is set differently for Windows.
1236    
1237    15. Added a second compiling function called pcre_compile2(). The only
1238        difference is that it has an extra argument, which is a pointer to an
1239        integer error code. When there is a compile-time failure, this is set
1240        non-zero, in addition to the error test pointer being set to point to an
1241        error message. The new argument may be NULL if no error number is required
1242        (but then you may as well call pcre_compile(), which is now just a
1243        wrapper). This facility is provided because some applications need a
1244        numeric error indication, but it has also enabled me to tidy up the way
1245        compile-time errors are handled in the POSIX wrapper.
1246    
1247    16. Added VPATH=.libs to the makefile; this should help when building with one
1248        prefix path and installing with another. (Or so I'm told by someone who
1249        knows more about this stuff than I do.)
1250    
1251    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1252        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1253        match everything, including newlines. This is not POSIX-compatible, but
1254        somebody wanted the feature. From pcretest it can be activated by using
1255        both the P and the s flags.
1256    
1257    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1258    
1259    19. libpcre.pc was being incorrectly installed as executable.
1260    
1261    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1262        it now also looks for '\r' so that it will work unmodified on Windows.
1263    
1264    21. Added Google's contributed C++ wrapper to the distribution.
1265    
1266    22. Added some untidy missing memory free() calls in pcretest, to keep
1267        Electric Fence happy when testing.
1268    
1269    
1270    
1271    Version 5.0 13-Sep-04
1272    ---------------------
1273    
1274     1. Internal change: literal characters are no longer packed up into items
1275        containing multiple characters in a single byte-string. Each character
1276        is now matched using a separate opcode. However, there may be more than one
1277        byte in the character in UTF-8 mode.
1278    
1279     2. The pcre_callout_block structure has two new fields: pattern_position and
1280        next_item_length. These contain the offset in the pattern to the next match
1281        item, and its length, respectively.
1282    
1283     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1284        insertion of callouts before each pattern item. Added the /C option to
1285        pcretest to make use of this.
1286    
1287     4. On the advice of a Windows user, the lines
1288    
1289          #if defined(_WIN32) || defined(WIN32)
1290          _setmode( _fileno( stdout ), 0x8000 );
1291          #endif  /* defined(_WIN32) || defined(WIN32) */
1292    
1293        have been added to the source of pcretest. This apparently does useful
1294        magic in relation to line terminators.
1295    
1296     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1297        for the benefit of those environments where the "b" makes a difference.
1298    
1299     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1300        to know about it. I have put a hack into configure.in that adds in code
1301        to set GCC=yes if CC=icc. This seems to end up at a point in the
1302        generated configure script that is early enough to affect the setting of
1303        compiler options, which is what is needed, but I have no means of testing
1304        whether it really works. (The user who reported this had patched the
1305        generated configure script, which of course I cannot do.)
1306    
1307        LATER: After change 22 below (new libtool files), the configure script
1308        seems to know about icc (and also ecc). Therefore, I have commented out
1309        this hack in configure.in.
1310    
1311     7. Added support for pkg-config (2 patches were sent in).
1312    
1313     8. Negated POSIX character classes that used a combination of internal tables
1314        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1315        [[:^ascii]]. Typically, they would match almost any characters. The other
1316        POSIX classes were not broken in this way.
1317    
1318     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1319        to find the match, as PCRE was deluded into thinking that the match had to
1320        start at the start point or following a newline. The same bug applied to
1321        patterns with negative forward assertions or any backward assertions
1322        preceding ".*" at the start, unless the pattern required a fixed first
1323        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1324    
1325    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1326        starting at the last subject character, bytes beyond the end of the subject
1327        string were read.
1328    
1329    11. Renamed the variable "class" as "classbits" to make life easier for C++
1330        users. (Previously there was a macro definition, but it apparently wasn't
1331        enough.)
1332    
1333    12. Added the new field "tables" to the extra data so that tables can be passed
1334        in at exec time, or the internal tables can be re-selected. This allows
1335        a compiled regex to be saved and re-used at a later time by a different
1336        program that might have everything at different addresses.
1337    
1338    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1339        -R library as well as a -L library.
1340    
1341    14. The debugging options of pcretest (-d on the command line or D on a
1342        pattern) showed incorrect output for anything following an extended class
1343        that contained multibyte characters and which was followed by a quantifier.
1344    
1345    15. Added optional support for general category Unicode character properties
1346        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1347        support. It adds about 90K to the size of the library. The meanings of the
1348        inbuilt class escapes such as \d and \s have NOT been changed.
1349    
1350    16. Updated pcredemo.c to include calls to free() to release the memory for the
1351        compiled pattern.
1352    
1353    17. The generated file chartables.c was being created in the source directory
1354        instead of in the building directory. This caused the build to fail if the
1355        source directory was different from the building directory, and was
1356        read-only.
1357    
1358    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1359        file. No doubt somebody will tell me if they don't make sense... Also added
1360        Dan Mooney's comments about building on OpenVMS.
1361    
1362    19. Added support for partial matching via the PCRE_PARTIAL option for
1363        pcre_exec() and the \P data escape in pcretest.
1364    
1365    20. Extended pcretest with 3 new pattern features:
1366    
1367        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1368              write the compiled pattern to the file whose name is "rest-of-line".
1369              This is a straight binary dump of the data, with the saved pointer to
1370              the character tables forced to be NULL. The study data, if any, is
1371              written too. After writing, pcretest reads a new pattern.
1372    
1373        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1374              compiled pattern from the given file. There must not be any
1375              occurrences of "<" in the file name (pretty unlikely); if there are,
1376              pcretest will instead treat the initial "<" as a pattern delimiter.
1377              After reading in the pattern, pcretest goes on to read data lines as
1378              usual.
1379    
1380        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1381              and 16-bit fields in a compiled pattern, to simulate a pattern that
1382              was compiled on a host of opposite endianness.
1383    
1384    21. The pcre-exec() function can now cope with patterns that were compiled on
1385        hosts of opposite endianness, with this restriction:
1386    
1387          As for any compiled expression that is saved and used later, the tables
1388          pointer field cannot be preserved; the extra_data field in the arguments
1389          to pcre_exec() should be used to pass in a tables address if a value
1390          other than the default internal tables were used at compile time.
1391    
1392    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1393        now diagnosed as an error. Previously, most of the time, a negative number
1394        would have been treated as zero, but if in addition "ovector" was passed as
1395        NULL, a crash could occur.
1396    
1397    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1398        new versions from the libtool 1.5 distribution (the last one is a copy of
1399        a file called libtool.m4). This seems to have fixed the need to patch
1400        "configure" to support Darwin 1.3 (which I used to do). However, I still
1401        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1402        workstation).
1403    
1404    24. Changed the PCRE licence to be the more standard "BSD" licence.
1405    
1406    
1407    Version 4.5 01-Dec-03
1408    ---------------------
1409    
1410     1. There has been some re-arrangement of the code for the match() function so
1411        that it can be compiled in a version that does not call itself recursively.
1412        Instead, it keeps those local variables that need separate instances for
1413        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1414        needs to "recurse". Keeping track of where control must go is done by means
1415        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1416        hide most of the details from the main code, and operates only if
1417        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1418        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1419        operating.
1420    
1421        To make it easier for callers to provide specially tailored get/free
1422        functions for this usage, two new functions, pcre_stack_malloc, and
1423        pcre_stack_free, are used. They are always called in strict stacking order,
1424        and the size of block requested is always the same.
1425    
1426        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1427        PCRE has been compiled to use the stack or the heap for recursion. The
1428        -C option of pcretest uses this to show which version is compiled.
1429    
1430        A new data escape \S, is added to pcretest; it causes the amounts of store
1431        obtained and freed by both kinds of malloc/free at match time to be added
1432        to the output.
1433    
1434     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1435        what's available on my current Linux desktop machine.
1436    
1437     3. When matching a UTF-8 string, the test for a valid string at the start has
1438        been extended. If start_offset is not zero, PCRE now checks that it points
1439        to a byte that is the start of a UTF-8 character. If not, it returns
1440        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1441        this is necessary because there may be backward assertions in the pattern.
1442        When matching the same subject several times, it may save resources to use
1443        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1444    
1445     4. The code for checking the validity of UTF-8 strings has been tightened so
1446        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1447        containing "overlong sequences".
1448    
1449     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1450        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1451        should have been "&", but it just so happened that all the cases this let
1452        through by mistake were picked up later in the function.
1453    
1454     6. I had used a variable called "isblank" - this is a C99 function, causing
1455        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1456    
1457     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1458        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1459        so the version is shown; (c) stop "make test" echoing "./RunTest".
1460    
1461     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1462    
1463     9. The prototype for memmove() for systems that don't have it was using
1464        size_t, but the inclusion of the header that defines size_t was later. I've
1465        moved the #includes for the C headers earlier to avoid this.
1466    
1467    10. Added some adjustments to the code to make it easier to compiler on certain
1468        special systems:
1469    
1470          (a) Some "const" qualifiers were missing.
1471          (b) Added the macro EXPORT before all exported functions; by default this
1472              is defined to be empty.
1473          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1474              that it reads its output file name as an argument instead of writing
1475              to the standard output and assuming this can be redirected.
1476    
1477    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1478        class containing characters with values greater than 255, PCRE compilation
1479        went into a loop.
1480    
1481    12. A recursive reference to a subpattern that was within another subpattern
1482        that had a minimum quantifier of zero caused PCRE to crash. For example,
1483        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1484        recursion. If the recursively-called subpattern itself had a zero repeat,
1485        that was OK.
1486    
1487    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1488        buffer into which it was copied (for escape processing) was still set at
1489        1024, so long lines caused crashes.
1490    
1491    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1492        "internal error: code overflow...". This applied to any character class
1493        that was followed by a possessive quantifier.
1494    
1495    15. Modified the Makefile to add libpcre.la as a prerequisite for
1496        libpcreposix.la because I was told this is needed for a parallel build to
1497        work.
1498    
1499    16. If a pattern that contained .* following optional items at the start was
1500        studied, the wrong optimizing data was generated, leading to matching
1501        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1502        matching string must start with a or b or c. The correct conclusion for
1503        this pattern is that a match can start with any character.
1504    
1505    
1506    Version 4.4 13-Aug-03
1507    ---------------------
1508    
1509     1. In UTF-8 mode, a character class containing characters with values between
1510        127 and 255 was not handled correctly if the compiled pattern was studied.
1511        In fixing this, I have also improved the studying algorithm for such
1512        classes (slightly).
1513    
1514     2. Three internal functions had redundant arguments passed to them. Removal
1515        might give a very teeny performance improvement.
1516    
1517     3. Documentation bug: the value of the capture_top field in a callout is *one
1518        more than* the number of the hightest numbered captured substring.
1519    
1520     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1521        in incorrectly linking with a previously installed version. They now link
1522        explicitly with libpcre.la.
1523    
1524     5. configure.in no longer needs to recognize Cygwin specially.
1525    
1526     6. A problem in pcre.in for Windows platforms is fixed.
1527    
1528     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1529        pcretest, it used to include the size of the study block as part of its
1530        output. Unfortunately, the structure contains a field that has a different
1531        size on different hardware architectures. This meant that the tests that
1532        showed this size failed. As the block is currently always of a fixed size,
1533        this information isn't actually particularly useful in pcretest output, so
1534        I have just removed it.
1535    
1536     8. Three pre-processor statements accidentally did not start in column 1.
1537        Sadly, there are *still* compilers around that complain, even though
1538        standard C has not required this for well over a decade. Sigh.
1539    
1540     9. In pcretest, the code for checking callouts passed small integers in the
1541        callout_data field, which is a void * field. However, some picky compilers
1542        complained about the casts involved for this on 64-bit systems. Now
1543        pcretest passes the address of the small integer instead, which should get
1544        rid of the warnings.
1545    
1546    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1547        both compile and run time, and gives an error if an invalid UTF-8 sequence
1548        is found. There is a option for disabling this check in cases where the
1549        string is known to be correct and/or the maximum performance is wanted.
1550    
1551    11. In response to a bug report, I changed one line in Makefile.in from
1552    
1553            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1554        to
1555            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1556    
1557        to look similar to other lines, but I have no way of telling whether this
1558        is the right thing to do, as I do not use Windows. No doubt I'll get told
1559        if it's wrong...
1560    
1561    
1562    Version 4.3 21-May-03
1563    ---------------------
1564    
1565    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1566       Makefile.
1567    
1568    2. Some refactoring to improve the quality of the code:
1569    
1570       (i)   The utf8_table... variables are now declared "const".
1571    
1572       (ii)  The code for \cx, which used the "case flipping" table to upper case
1573             lower case letters, now just substracts 32. This is ASCII-specific,
1574             but the whole concept of \cx is ASCII-specific, so it seems
1575             reasonable.
1576    
1577       (iii) PCRE was using its character types table to recognize decimal and
1578             hexadecimal digits in the pattern. This is silly, because it handles
1579             only 0-9, a-f, and A-F, but the character types table is locale-
1580             specific, which means strange things might happen. A private
1581             table is now used for this - though it costs 256 bytes, a table is
1582             much faster than multiple explicit tests. Of course, the standard
1583             character types table is still used for matching digits in subject
1584             strings against \d.
1585    
1586       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1587             ending in _t are). So I've renamed it as ESC_tee.
1588    
1589    3. The first argument for regexec() in the POSIX wrapper should have been
1590       defined as "const".
1591    
1592    4. Changed pcretest to use malloc() for its buffers so that they can be
1593       Electric Fenced for debugging.
1594    
1595    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1596       to read one or more bytes before the start of the subject string. Often this
1597       had no effect on PCRE's behaviour, but in some circumstances it could
1598       provoke a segmentation fault.
1599    
1600    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1601       to try to read one or more bytes before the start of the subject string.
1602    
1603    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1604       UTF-8 support could misbehave in various ways if the subject string
1605       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1606       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1607       back over UTF-8 characters.)
1608    
1609    
1610    Version 4.2 14-Apr-03
1611    ---------------------
1612    
1613    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1614    
1615    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1616         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1617         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1618         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1619         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1620           and BUILD_EXEEXT
1621         Note: automatic setting of the BUILD variables is not yet working
1622         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1623           compile-time but not at link-time
1624         [LINK]: use for linking executables only
1625         make different versions for Windows and non-Windows
1626         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1627           libraries
1628         [LINK_FOR_BUILD]: new variable
1629         [OBJEXT]: use throughout
1630         [EXEEXT]: use throughout
1631         <winshared>: new target
1632         <wininstall>: new target
1633         <dftables.o>: use native compiler
1634         <dftables>: use native linker
1635         <install>: handle Windows platform correctly
1636         <clean>: ditto
1637         <check>: ditto
1638         copy DLL to top builddir before testing
1639    
1640       As part of these changes, -no-undefined was removed again. This was reported
1641       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1642       in any case.
1643    
1644    3. Some tidies to get rid of compiler warnings:
1645    
1646       . In the match_data structure, match_limit was an unsigned long int, whereas
1647         match_call_count was an int. I've made them both unsigned long ints.
1648    
1649       . In pcretest the fact that a const uschar * doesn't automatically cast to
1650         a void * provoked a warning.
1651    
1652       . Turning on some more compiler warnings threw up some "shadow" variables
1653         and a few more missing casts.
1654    
1655    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1656       option, a class that contained a single character with a value between 128
1657       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1658    
1659    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1660       option, a class that contained several characters, but with at least one
1661       whose value was between 128 and 255 caused PCRE to crash.
1662    
1663    
1664    Version 4.1 12-Mar-03
1665    ---------------------
1666    
1667    1. Compiling with gcc -pedantic found a couple of places where casts were
1668    needed, and a string in dftables.c that was longer than standard compilers are
1669    required to support.
1670    
1671    2. Compiling with Sun's compiler found a few more places where the code could
1672    be tidied up in order to avoid warnings.
1673    
1674    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1675    first of these names is deprecated in the latest Autoconf in favour of the name
1676    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1677    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1678    analogy I have changed it to CFLAGS_FOR_BUILD.
1679    
1680    4. Added -no-undefined to the linking command in the Makefile, because this is
1681    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1682    linking step for the pcreposix library.
1683    
1684    5. PCRE was failing to diagnose the case of two named groups with the same
1685    name.
1686    
1687    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1688    literal character that is needed in the subject for a match, and scans along to
1689    ensure that it is present before embarking on the full matching process. This
1690    saves time in cases of nested unlimited repeats that are never going to match.
1691    Problem: the scan can take a lot of time if the subject is very long (e.g.
1692    megabytes), thus penalizing straightforward matches. It is now done only if the
1693    amount of subject to be scanned is less than 1000 bytes.
1694    
1695    7. A lesser problem with the same optimization is that it was recording the
1696    first character of an anchored pattern as "needed", thus provoking a search
1697    right along the subject, even when the first match of the pattern was going to
1698    fail. The "needed" character is now not set for anchored patterns, unless it
1699    follows something in the pattern that is of non-fixed length. Thus, it still
1700    fulfils its original purpose of finding quick non-matches in cases of nested
1701    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1702    
1703    
1704    Version 4.0 17-Feb-03
1705    ---------------------
1706    
1707    1. If a comment in an extended regex that started immediately after a meta-item
1708    extended to the end of string, PCRE compiled incorrect data. This could lead to
1709    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1710    
1711    2. Moved to autoconf 2.53 and libtool 1.4.2.
1712    
1713    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1714    the special perltest8 script is no longer needed - all the tests can be run
1715    from a single perltest script.
1716    
1717    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1718    by \s. It has now been removed in PCRE. This means it isn't recognized as
1719    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1720    class [:space:] *does* include VT, thereby creating a mess.
1721    
1722    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1723    space and tab.
1724    
1725    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1726    its new features into the main test script, reducing the number of scripts.
1727    
1728    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1729    were backward compatible, and made the (?i) apply to the whole pattern, as if
1730    /i were given. Now it behaves more logically, and applies the option setting
1731    only to what follows. PCRE has been changed to follow suit. However, if it
1732    finds options settings right at the start of the pattern, it extracts them into
1733    the global options, as before. Thus, they show up in the info data.
1734    
1735    8. Added support for the \Q...\E escape sequence. Characters in between are
1736    treated as literals. This is slightly different from Perl in that $ and @ are
1737    also handled as literals inside the quotes. In Perl, they will cause variable
1738    interpolation. Note the following examples:
1739    
1740        Pattern            PCRE matches      Perl matches
1741    
1742        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
1743        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
1744        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
1745    
1746    For compatibility with Perl, \Q...\E sequences are recognized inside character
1747    classes as well as outside them.
1748    
1749    9. Re-organized 3 code statements in pcretest to avoid "overflow in
1750    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1751    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1752    signed/unsigned warnings.
1753    
1754    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1755    option for pcretest, so I've replaced it by a simple function that does just
1756    that job.
1757    
1758    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1759    "pcregrep -".
1760    
1761    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1762    Java package. This provides some syntactic sugar for simple cases of what my
1763    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1764    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1765    item, you can use this simplified notation. Note that only makes sense with
1766    greedy quantifiers. Consequently, the use of the possessive quantifier forces
1767    greediness, whatever the setting of the PCRE_UNGREEDY option.
1768    
1769    13. A change of greediness default within a pattern was not taking effect at
1770    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1771    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1772    was abstracted outside.
1773    
1774    14. PCRE now supports the \G assertion. It is true when the current matching
1775    position is at the start point of the match. This differs from \A when the
1776    starting offset is non-zero. Used with the /g option of pcretest (or similar
1777    code), it works in the same way as it does for Perl's /g option. If all
1778    alternatives of a regex begin with \G, the expression is anchored to the start
1779    match position, and the "anchored" flag is set in the compiled expression.
1780    
1781    15. Some bugs concerning the handling of certain option changes within patterns
1782    have been fixed. These applied to options other than (?ims). For example,
1783    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1784    been the other way round. Some of this was related to change 7 above.
1785    
1786    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1787    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1788    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1789    POSIX classes only within a class (e.g. /[[:alpha:]]/).
1790    
1791    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1792    mode. Unlike ".", it always matches newline, whatever the setting of
1793    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1794    assertions. Perl allows it, but it doesn't (in general) work because it can't
1795    calculate the length of the lookbehind. At least, that's the case for Perl
1796    5.8.0 - I've been told they are going to document that it doesn't work in
1797    future.
1798    
1799    18. Added an error diagnosis for escapes that PCRE does not support: these are
1800    \L, \l, \N, \P, \p, \U, \u, and \X.
1801    
1802    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1803    reading past the end of the pattern in cases such as /[abcd/.
1804    
1805    20. PCRE was getting more memory than necessary for patterns with classes that
1806    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1807    
1808    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1809    compiling PCRE for use with Virtual Pascal.
1810    
1811    22. Small fix to the Makefile to make it work properly if the build is done
1812    outside the source tree.
1813    
1814    23. Added a new extension: a condition to go with recursion. If a conditional
1815    subpattern starts with (?(R) the "true" branch is used if recursion has
1816    happened, whereas the "false" branch is used only at the top level.
1817    
1818    24. When there was a very long string of literal characters (over 255 bytes
1819    without UTF support, over 250 bytes with UTF support), the computation of how
1820    much memory was required could be incorrect, leading to segfaults or other
1821    strange effects.
1822    
1823    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1824    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1825    there was a subsequent back reference to those brackets. This meant that, for
1826    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1827    possible to check for precisely this case. All we can do is abandon the
1828    optimization if .* occurs inside capturing brackets when there are any back
1829    references whatsoever. (See below for a better fix that came later.)
1830    
1831    26. The handling of the optimization for finding the first character of a
1832    non-anchored pattern, and for finding a character that is required later in the
1833    match were failing in some cases. This didn't break the matching; it just
1834    failed to optimize when it could. The way this is done has been re-implemented.
1835    
1836    27. Fixed typo in error message for invalid (?R item (it said "(?p").
1837    
1838    28. Added a new feature that provides some of the functionality that Perl
1839    provides with (?{...}). The facility is termed a "callout". The way it is done
1840    in PCRE is for the caller to provide an optional function, by setting
1841    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1842    global variable. By default it is unset, which disables all calling out. To get
1843    the function called, the regex must include (?C) at appropriate points. This
1844    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1845    This provides a means of identifying different callout points. When PCRE
1846    reaches such a point in the regex, if pcre_callout has been set, the external
1847    function is called. It is provided with data in a structure called
1848    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1849    matching continues; if it returns a non-zero value, the match at the current
1850    point fails. However, backtracking will occur if possible. [This was changed
1851    later and other features added - see item 49 below.]
1852    
1853    29. pcretest is upgraded to test the callout functionality. It provides a
1854    callout function that displays information. By default, it shows the start of
1855    the match and the current position in the text. There are some new data escapes
1856    to vary what happens:
1857    
1858        \C+         in addition, show current contents of captured substrings
1859        \C-         do not supply a callout function
1860        \C!n        return 1 when callout number n is reached
1861        \C!n!m      return 1 when callout number n is reached for the mth time
1862    
1863    30. If pcregrep was called with the -l option and just a single file name, it
1864    output "<stdin>" if a match was found, instead of the file name.
1865    
1866    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1867    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1868    pcre_exec(). This saves a malloc/free per call. The default value of
1869    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1870    when configuring.
1871    
1872    32. The default maximum size of a compiled pattern is 64K. There have been a
1873    few cases of people hitting this limit. The code now uses macros to handle the
1874    storing of links as offsets within the compiled pattern. It defaults to 2-byte
1875    links, but this can be changed to 3 or 4 bytes by --with-link-size when
1876    configuring. Tests 2 and 5 work only with 2-byte links because they output
1877    debugging information about compiled patterns.
1878    
1879    33. Internal code re-arrangements:
1880    
1881    (a) Moved the debugging function for printing out a compiled regex into
1882        its own source file (printint.c) and used #include to pull it into
1883        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1884        separate copies.
1885    
1886    (b) Defined the list of op-code names for debugging as a macro in
1887        internal.h so that it is next to the definition of the opcodes.
1888    
1889    (c) Defined a table of op-code lengths for simpler skipping along compiled
1890        code. This is again a macro in internal.h so that it is next to the
1891        definition of the opcodes.
1892    
1893    34. Added support for recursive calls to individual subpatterns, along the
1894    lines of Robin Houston's patch (but implemented somewhat differently).
1895    
1896    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1897    allow it to read and process whole directories in Win32. This code was
1898    contributed by Lionel Fourquaux; it has not been tested by me.
1899    
1900    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1901    used to name a group. Names consist of alphanumerics and underscores, and must
1902    be unique. Back references use the syntax (?P=name) and recursive calls use
1903    (?P>name) which is a PCRE extension to the Python extension. Groups still have
1904    numbers. The function pcre_fullinfo() can be used after compilation to extract
1905    a name/number map. There are three relevant calls:
1906    
1907      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
1908      PCRE_INFO_NAMECOUNT            yields the number of entries
1909      PCRE_INFO_NAMETABLE            yields a pointer to the map.
1910    
1911    The map is a vector of fixed-size entries. The size of each entry depends on
1912    the length of the longest name used. The first two bytes of each entry are the
1913    group number, most significant byte first. There follows the corresponding
1914    name, zero terminated. The names are in alphabetical order.
1915    
1916    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1917    case instead of 255. Making it the same both with and without UTF-8 support
1918    means that the same test output works with both.
1919    
1920    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1921    calling malloc() with a zero argument.
1922    
1923    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1924    optimization. I've improved things by keeping a bitmap of backreferences with
1925    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1926    fact referenced, the optimization can be applied. It is unlikely that a
1927    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1928    the match to follow \n) will appear inside brackets with a number greater than
1929    31, but if it does, any back reference > 31 suppresses the optimization.
1930    
1931    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1932    of disabling numbered capturing parentheses. Any opening parenthesis that is
1933    not followed by ? behaves as if it were followed by ?: but named parentheses
1934    can still be used for capturing (and they will acquire numbers in the usual
1935    way).
1936    
1937    41. Redesigned the return codes from the match() function into yes/no/error so
1938    that errors can be passed back from deep inside the nested calls. A malloc
1939    failure while inside a recursive subpattern call now causes the
1940    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1941    
1942    42. It is now possible to set a limit on the number of times the match()
1943    function is called in a call to pcre_exec(). This facility makes it possible to
1944    limit the amount of recursion and backtracking, though not in a directly
1945    obvious way, because the match() function is used in a number of different
1946    circumstances. The count starts from zero for each position in the subject
1947    string (for non-anchored patterns). The default limit is, for compatibility, a
1948    large number, namely 10 000 000. You can change this in two ways:
1949    
1950    (a) When configuring PCRE before making, you can use --with-match-limit=n
1951        to set a default value for the compiled library.
1952    
1953    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1954        a different value is set. See 45 below.
1955    
1956    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1957    
1958    43. Added a new function pcre_config(int, void *) to enable run-time extraction
1959    of things that can be changed at compile time. The first argument specifies
1960    what is wanted and the second points to where the information is to be placed.
1961    The current list of available information is:
1962    
1963      PCRE_CONFIG_UTF8
1964    
1965    The output is an integer that is set to one if UTF-8 support is available;
1966    otherwise it is set to zero.
1967    
1968      PCRE_CONFIG_NEWLINE
1969    
1970    The output is an integer that it set to the value of the code that is used for
1971    newline. It is either LF (10) or CR (13).
1972    
1973      PCRE_CONFIG_LINK_SIZE
1974    
1975    The output is an integer that contains the number of bytes used for internal
1976    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
1977    
1978      PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
1979    
1980    The output is an integer that contains the threshold above which the POSIX
1981    interface uses malloc() for output vectors. See item 31 above.
1982    
1983      PCRE_CONFIG_MATCH_LIMIT
1984    
1985    The output is an unsigned integer that contains the default limit of the number
1986    of match() calls in a pcre_exec() execution. See 42 above.
1987    
1988    44. pcretest has been upgraded by the addition of the -C option. This causes it
1989    to extract all the available output from the new pcre_config() function, and to
1990    output it. The program then exits immediately.
1991    
1992    45. A need has arisen to pass over additional data with calls to pcre_exec() in
1993    order to support additional features. One way would have been to define
1994    pcre_exec2() (for example) with extra arguments, but this would not have been
1995    extensible, and would also have required all calls to the original function to
1996    be mapped to the new one. Instead, I have chosen to extend the mechanism that
1997    is used for passing in "extra" data from pcre_study().
1998    
1999    The pcre_extra structure is now exposed and defined in pcre.h. It currently
2000    contains the following fields:
2001    
2002      flags         a bitmap indicating which of the following fields are set
2003      study_data    opaque data from pcre_study()
2004      match_limit   a way of specifying a limit on match() calls for a specific
2005                      call to pcre_exec()
2006      callout_data  data for callouts (see 49 below)
2007    
2008    The flag bits are also defined in pcre.h, and are
2009    
2010      PCRE_EXTRA_STUDY_DATA
2011      PCRE_EXTRA_MATCH_LIMIT
2012      PCRE_EXTRA_CALLOUT_DATA
2013    
2014    The pcre_study() function now returns one of these new pcre_extra blocks, with
2015    the actual study data pointed to by the study_data field, and the
2016    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
2017    before. That is, this change is entirely upwards-compatible and requires no
2018    change to existing code.
2019    
2020    If you want to pass in additional data to pcre_exec(), you can either place it
2021    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2022    block.
2023    
2024    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2025    data string contains the escape sequence \M, pcretest calls pcre_exec() several
2026    times with different match limits, until it finds the minimum value needed for
2027    pcre_exec() to complete. The value is then output. This can be instructive; for
2028    most simple matches the number is quite small, but for pathological cases it
2029    gets very large very quickly.
2030    
2031    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2032    returns the size of the data block pointed to by the study_data field in a
2033    pcre_extra block, that is, the value that was passed as the argument to
2034    pcre_malloc() when PCRE was getting memory in which to place the information
2035    created by pcre_study(). The fourth argument should point to a size_t variable.
2036    pcretest has been extended so that this information is shown after a successful
2037    pcre_study() call when information about the compiled regex is being displayed.
2038    
2039    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2040    because what follows is always an absolute path. (Later: it turns out that this
2041    is more than cosmetic for MinGW, because it doesn't like empty path
2042    components.)
2043    
2044    49. Some changes have been made to the callout feature (see 28 above):
2045    
2046    (i)  A callout function now has three choices for what it returns:
2047    
2048           0  =>  success, carry on matching
2049         > 0  =>  failure at this point, but backtrack if possible
2050         < 0  =>  serious error, return this value from pcre_exec()
2051    
2052         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2053         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2054         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2055         use by callout functions. It will never be used by PCRE itself.
2056    
2057    (ii) The pcre_extra structure (see 45 above) has a void * field called
2058         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2059         pcre_callout_block structure has a field of the same name. The contents of
2060         the field passed in the pcre_extra structure are passed to the callout
2061         function in the corresponding field in the callout block. This makes it
2062         easier to use the same callout-containing regex from multiple threads. For
2063         testing, the pcretest program has a new data escape
2064    
2065           \C*n        pass the number n (may be negative) as callout_data
2066    
2067         If the callout function in pcretest receives a non-zero value as
2068         callout_data, it returns that value.
2069    
2070    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2071    there were some redundant $(CFLAGS) in commands that are now specified as
2072    $(LINK), which already includes $(CFLAGS).
2073    
2074    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2075    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2076    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2077    one-byte characters throughout. Note that case-insensitive matching applies
2078    only to characters whose values are less than 256. PCRE doesn't support the
2079    notion of cases for higher-valued characters.
2080    
2081    (i)   A character class whose characters are all within 0-255 is handled as
2082          a bit map, and the map is inverted for negative classes. Previously, a
2083          character > 255 always failed to match such a class; however it should
2084          match if the class was a negative one (e.g. [^ab]). This has been fixed.
2085    
2086    (ii)  A negated character class with a single character < 255 is coded as
2087          "not this character" (OP_NOT). This wasn't working properly when the test
2088          character was multibyte, either singly or repeated.
2089    
2090    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2091          mode, for example: \x{100}{2,3}.
2092    
2093    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2094          singly or repeated) now correctly test multibyte characters. However,
2095          PCRE doesn't recognize any characters with values greater than 255 as
2096          digits, spaces, or word characters. Such characters always match \D, \S,
2097          and \W, and never match \d, \s, or \w.
2098    
2099    (v)   Classes may now contain characters and character ranges with values
2100          greater than 255. For example: [ab\x{100}-\x{400}].
2101    
2102    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
2103          PCRE in UTF-8 mode.
2104    
2105    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2106    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2107    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2108    value.)
2109    
2110    53. The single man page has become too large. I have therefore split it up into
2111    a number of separate man pages. These also give rise to individual HTML pages;
2112    these are now put in a separate directory, and there is an index.html page that
2113    lists them all. Some hyperlinking between the pages has been installed.
2114    
2115    54. Added convenience functions for handling named capturing parentheses.
2116    
2117    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2118    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2119    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2120    are faulted.
2121    
2122    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2123    calling configure. These values are used when compiling the dftables.c program
2124    which is run to generate the source of the default character tables. They
2125    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2126    you will need to set these values.
2127    
2128    57. Updated the building process for Windows DLL, as provided by Fred Cox.
2129    
2130    
2131    Version 3.9 02-Jan-02
2132    ---------------------
2133    
2134    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
2135    
2136    2. If --disable-static was given, the building process failed when trying to
2137    build pcretest and pcregrep. (For some reason it was using libtool to compile
2138    them, which is not right, as they aren't part of the library.)
2139    
2140    
2141    Version 3.8 18-Dec-01
2142    ---------------------
2143    
2144    1. The experimental UTF-8 code was completely screwed up. It was packing the
2145    bytes in the wrong order. How dumb can you get?
2146    
2147    
2148    Version 3.7 29-Oct-01
2149    ---------------------
2150    
2151    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
2152    This caused pcretest, when used on the test data, to segfault. Unfortunately,
2153    this didn't happen under Solaris 8, where I normally test things.
2154    
2155    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
2156    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
2157    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
2158    this fix an hour or so after the initial 3.7 release.)
2159    
2160    
2161    Version 3.6 23-Oct-01
2162    ---------------------
2163    
2164    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
2165    offsets passed as NULL with zero offset count.
2166    
2167    2. The config.guess and config.sub files had not been updated when I moved to
2168    the latest autoconf.
2169    
2170    
2171    Version 3.5 15-Aug-01
2172    ---------------------
2173    
2174    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2175    had been forgotten.
2176    
2177    2. By using declared but undefined structures, we can avoid using "void"
2178    definitions in pcre.h while keeping the internal definitions of the structures
2179    private.
2180    
2181    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2182    user point of view, this means that both static and shared libraries are built
2183    by default, but this can be individually controlled. More of the work of
2184    handling this static/shared cases is now inside libtool instead of PCRE's make
2185    file.
2186    
2187    4. The pcretest utility is now installed along with pcregrep because it is
2188    useful for users (to test regexs) and by doing this, it automatically gets
2189    relinked by libtool. The documentation has been turned into a man page, so
2190    there are now .1, .txt, and .html versions in /doc.
2191    
2192    5. Upgrades to pcregrep:
2193       (i)   Added long-form option names like gnu grep.
2194       (ii)  Added --help to list all options with an explanatory phrase.
2195       (iii) Added -r, --recursive to recurse into sub-directories.
2196       (iv)  Added -f, --file to read patterns from a file.
2197    
2198    6. pcre_exec() was referring to its "code" argument before testing that
2199    argument for NULL (and giving an error if it was NULL).
2200    
2201    7. Upgraded Makefile.in to allow for compiling in a different directory from
2202    the source directory.
2203    
2204    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2205    options bits, the pointer it was passed was to an int instead of to an unsigned
2206    long int. This mattered only on 64-bit systems.
2207    
2208    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2209    generated) instead of pcre.in, which it its source. Also made the same change
2210    in several of the .c files.
2211    
2212    10. A new release of gcc defines printf() as a macro, which broke pcretest
2213    because it had an ifdef in the middle of a string argument for printf(). Fixed
2214    by using separate calls to printf().
2215    
2216    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2217    script, to force use of CR or LF instead of \n in the source. On non-Unix
2218    systems, the value can be set in config.h.
2219    
2220    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2221    absolute limit. Changed the text of the error message to make this clear, and
2222    likewise updated the man page.
2223    
2224    13. The limit of 99 on the number of capturing subpatterns has been removed.
2225    The new limit is 65535, which I hope will not be a "real" limit.
2226    
2227    
2228    Version 3.4 22-Aug-00
2229    ---------------------
2230    
2231    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2232    
2233    2. Diagnose condition (?(0) as an error instead of crashing on matching.
2234    
2235    
2236    Version 3.3 01-Aug-00
2237    ---------------------
2238    
2239    1. If an octal character was given, but the value was greater than \377, it
2240    was not getting masked to the least significant bits, as documented. This could
2241    lead to crashes in some systems.
2242    
2243    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2244    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2245    
2246    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2247    These just pass their arguments on to (pcre_free)(), but they are provided
2248    because some uses of PCRE bind it to non-C systems that can call its functions,
2249    but cannot call free() or pcre_free() directly.
2250    
2251    4. Add "make test" as a synonym for "make check". Corrected some comments in
2252    the Makefile.
2253    
2254    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2255    Makefile.
2256    
2257    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2258    command called pgrep for grepping around the active processes.
2259    
2260    7. Added the beginnings of support for UTF-8 character strings.
2261    
2262    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2263    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2264    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2265    out for the ar command.)
2266    
2267    
2268    Version 3.2 12-May-00
2269    ---------------------
2270    
2271    This is purely a bug fixing release.
2272    
2273    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
2274    of ZA. This was just one example of several cases that could provoke this bug,
2275    which was introduced by change 9 of version 2.00. The code for breaking
2276    infinite loops after an iteration that matches an empty string was't working
2277    correctly.
2278    
2279    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
2280    when matched against abbab (for example). After matching an empty string, it
2281    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
2282    caused it to match further down the string than it should.
2283    
2284    3. The code contained an inclusion of sys/types.h. It isn't clear why this
2285    was there because it doesn't seem to be needed, and it causes trouble on some
2286    systems, as it is not a Standard C header. It has been removed.
2287    
2288    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
2289    were reported on the Macintosh. The changes were from
2290    
2291      while ((c = *(++ptr)) != 0 && c != '\n');
2292    to
2293      while ((c = *(++ptr)) != 0 && c != '\n') ;
2294    
2295    Totally extraordinary, but if that's what it takes...
2296    
2297    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2298    available. Added HAVE_BCOPY and an autoconf test for it; if neither
2299    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2300    assumes the way PCRE uses memmove() (always moving upwards).
2301    
2302    6. PCRE is being used in one environment where strchr() is not available. There
2303    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2304    faster code anyway.
2305    
2306    
2307    Version 3.1 09-Feb-00
2308    ---------------------
2309    
2310    The only change in this release is the fixing of some bugs in Makefile.in for
2311    the "install" target:
2312    
2313    (1) It was failing to install pcreposix.h.
2314    
2315    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2316    
2317    
2318    Version 3.0 01-Feb-00
2319    ---------------------
2320    
2321    1. Add support for the /+ modifier to perltest (to output $` like it does in
2322    pcretest).
2323    
2324    2. Add support for the /g modifier to perltest.
2325    
2326    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2327    matches null strings.
2328    
2329    4. Fix perltest so that it doesn't do unwanted things when fed an empty
2330    pattern. Perl treats empty patterns specially - it reuses the most recent
2331    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2332    effect.
2333    
2334    5. The POSIX interface was broken in that it was just handing over the POSIX
2335    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2336    required a bigger vector, with some working space on the end. This means that
2337    the POSIX wrapper now has to get and free some memory, and copy the results.
2338    
2339    6. Added some simple autoconf support, placing the test data and the
2340    documentation in separate directories, re-organizing some of the
2341    information files, and making it build pcre-config (a GNU standard). Also added
2342    libtool support for building PCRE as a shared library, which is now the
2343    default.
2344    
2345    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2346    09 are not valid octal constants. Single digits will be used for minor values
2347    less than 10.
2348    
2349    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2350    existing programs that set these in the POSIX interface can use PCRE without
2351    modification.
2352    
2353    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2354    return all that pcre_info() returns, plus additional data. The pcre_info()
2355    function is retained for compatibility, but is considered to be obsolete.
2356    
2357    10. Added experimental recursion feature (?R) to handle one common case that
2358    Perl 5.6 will be able to do with (?p{...}).
2359    
2360    11. Added support for POSIX character classes like [:alpha:], which Perl is
2361    adopting.
2362    
2363    
2364    Version 2.08 31-Aug-99
2365    ----------------------
2366    
2367    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2368    trying to match at the startoffset position, but instead was moving forward to
2369    the next newline as if a previous match had failed.
2370    
2371    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2372    and could get into a loop if a null string was matched other than at the start
2373    of the subject.
2374    
2375    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2376    be distinguished at compile time, and for completeness also added PCRE_DATE.
2377    
2378    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2379    in GnuWin32 environments.
2380    
2381    
2382    Version 2.07 29-Jul-99
2383    ----------------------
2384    
2385    1. The documentation is now supplied in plain text form and HTML as well as in
2386    the form of man page sources.
2387    
2388    2. C++ compilers don't like assigning (void *) values to other pointer types.
2389    In particular this affects malloc(). Although there is no problem in Standard
2390    C, I've put in casts to keep C++ compilers happy.
2391    
2392    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2393    should be (const char *).
2394    
2395    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2396    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2397    However, I haven't made this a standard facility. The documentation doesn't
2398    mention it, and the Makefile doesn't support it.
2399    
2400    5. The Makefile now contains an "install" target, with editable destinations at
2401    the top of the file. The pcretest program is not installed.
2402    
2403    6. pgrep -V now gives the PCRE version number and date.
2404    
2405    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2406    causing the entire string to be ignored, instead of just the last character.
2407    
2408    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2409    non-matching string, it can take a very, very long time, even for strings of
2410    quite modest length, because of the nested recursion. PCRE now does better in
2411    some of these cases. It does this by remembering the last required literal
2412    character in the pattern, and pre-searching the subject to ensure it is present
2413    before running the real match. In other words, it applies a heuristic to detect
2414    some types of certain failure quickly, and in the above example, if presented
2415    with a string that has no trailing " it gives "no match" very quickly.
2416    
2417    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2418    other alternatives are tried instead.
2419    
2420    
2421    Version 2.06 09-Jun-99
2422    ----------------------
2423    
2424    1. Change pcretest's output for amount of store used to show just the code
2425    space, because the remainder (the data block) varies in size between 32-bit and
2426    64-bit systems.
2427    
2428    2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2429    start matching at. This allows lookbehinds to work when searching for multiple
2430    occurrences in a string.
2431    
2432    3. Added additional options to pcretest for testing multiple occurrences:
2433    
2434       /+   outputs the rest of the string that follows a match
2435       /g   loops for multiple occurrences, using the new startoffset argument
2436       /G   loops for multiple occurrences by passing an incremented pointer
2437    
2438    4. PCRE wasn't doing the "first character" optimization for patterns starting
2439    with \b or \B, though it was doing it for other lookbehind assertions. That is,
2440    it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2441    the letter 'x'. On long subject strings, this gives a significant speed-up.
2442    
2443    
2444    Version 2.05 21-Apr-99
2445    ----------------------
2446    
2447    1. Changed the type of magic_number from int to long int so that it works
2448    properly on 16-bit systems.
2449    
2450    2. Fixed a bug which caused patterns starting with .* not to work correctly
2451    when the subject string contained newline characters. PCRE was assuming
2452    anchoring for such patterns in all cases, which is not correct because .* will
2453    not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
2454    DOTALL is set at top level; otherwise it knows that patterns starting with .*
2455    must be retried after every newline in the subject.
2456    
2457    
2458    Version 2.04 18-Feb-99
2459    ----------------------
2460    
2461    1. For parenthesized subpatterns with repeats whose minimum was zero, the
2462    computation of the store needed to hold the pattern was incorrect (too large).
2463    If such patterns were nested a few deep, this could multiply and become a real
2464    problem.
2465    
2466    2. Added /M option to pcretest to show the memory requirement of a specific
2467    pattern. Made -m a synonym of -s (which does this globally) for compatibility.
2468    
2469    3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
2470    compiled in such a way that the backtracking after subsequent failure was
2471    pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
2472    ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
2473    
2474    
2475    Version 2.03 02-Feb-99
2476    ----------------------
2477    
2478    1. Fixed typo and small mistake in man page.
2479    
2480    2. Added 4th condition (GPL supersedes if conflict) and created separate
2481    LICENCE file containing the conditions.
2482    
2483    3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
2484    Perl, that is the internal \ allows the delimiter to be included in the
2485    pattern. Locked out the use of \ as a delimiter. If \ immediately follows
2486    the final delimiter, add \ to the end of the pattern (to test the error).
2487    
2488    4. Added the convenience functions for extracting substrings after a successful
2489    match. Updated pcretest to make it able to test these functions.
2490    
2491    
2492    Version 2.02 14-Jan-99
2493    ----------------------
2494    
2495    1. Initialized the working variables associated with each extraction so that
2496    their saving and restoring doesn't refer to uninitialized store.
2497    
2498    2. Put dummy code into study.c in order to trick the optimizer of the IBM C
2499    compiler for OS/2 into generating correct code. Apparently IBM isn't going to
2500    fix the problem.
2501    
2502    3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
2503    calls, and wasn't printing the correct value for compiling calls. Increased the
2504    default value of LOOPREPEAT, and the number of significant figures in the
2505    times.
2506    
2507    4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
2508    
2509    5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
2510    a building problem on Windows NT with a FAT file system.
2511    
2512    
2513    Version 2.01 21-Oct-98
2514    ----------------------
2515    
2516    1. Changed the API for pcre_compile() to allow for the provision of a pointer
2517    to character tables built by pcre_maketables() in the current locale. If NULL
2518    is passed, the default tables are used.
2519    
2520    
2521  Version 2.00 24-Sep-98  Version 2.00 24-Sep-98
2522  ----------------------  ----------------------

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