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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.3 05-Jul-07
5    ---------------------
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:
13          #include "pcre.h"
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.
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.
27     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
29     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
30        in debug output.
34    Version 7.2 19-Jun-07
35    ---------------------
37     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
38        which is apparently normally available under Windows.
40     2. Re-jig the pcregrep tests with different newline settings in an attempt
41        to make them independent of the local environment's newline setting.
43     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
45     4. Some of the "internals" tests were previously cut out when the link size
46        was not 2, because the output contained actual offsets. The recent new
47        "Z" feature of pcretest means that these can be cut out, making the tests
48        usable with all link sizes.
50     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
51        stack recursion. This gives a massive performance boost under BSD, but just
52        a small improvement under Linux. However, it saves one field in the frame
53        in all cases.
55     6. Added more features from the forthcoming Perl 5.10:
57        (a) (?-n) (where n is a string of digits) is a relative subroutine or
58            recursion call. It refers to the nth most recently opened parentheses.
60        (b) (?+n) is also a relative subroutine call; it refers to the nth next
61            to be opened parentheses.
63        (c) Conditions that refer to capturing parentheses can be specified
64            relatively, for example, (?(-2)... or (?(+3)...
66        (d) \K resets the start of the current match so that everything before
67            is not part of it.
69        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
71        (f) \g{name} is another synonym - part of Perl 5.10's unification of
72            reference syntax.
74        (g) (?| introduces a group in which the numbering of parentheses in each
75            alternative starts with the same number.
77        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
79     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
82     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
83        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
84        for detecting groups that can match an empty string.
86     9. A pattern with a very large number of alternatives (more than several
87        hundred) was running out of internal workspace during the pre-compile
88        phase, where pcre_compile() figures out how much memory will be needed. A
89        bit of new cunning has reduced the workspace needed for groups with
90        alternatives. The 1000-alternative test pattern now uses 12 bytes of
91        workspace instead of running out of the 4096 that are available.
93    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
95    11. Applied patch from Google to remove an optimization that didn't quite work.
96        The report of the bug said:
98          pcrecpp::RE("a*").FullMatch("aaa") matches, while
99          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
100          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
102    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
103        it matched the wrong number of bytes.
106    Version 7.1 24-Apr-07
107    ---------------------
109     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
110        that is more "standard", making use of automake and other Autotools. There
111        is some re-arrangement of the files and adjustment of comments consequent
112        on this.
114     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
115        for recursive directory scanning broke on some systems because the files
116        are not scanned in any specific order and on different systems the order
117        was different. A call to "sort" has been inserted into RunGrepTest for the
118        approprate test as a short-term fix. In the longer term there may be an
119        alternative.
121     3. I had an email from Eric Raymond about problems translating some of PCRE's
122        man pages to HTML (despite the fact that I distribute HTML pages, some
123        people do their own conversions for various reasons). The problems
124        concerned the use of low-level troff macros .br and .in. I have therefore
125        removed all such uses from the man pages (some were redundant, some could
126        be replaced by .nf/.fi pairs). The 132html script that I use to generate
127        HTML has been updated to handle .nf/.fi and to complain if it encounters
128        .br or .in.
130     4. Updated comments in configure.ac that get placed in config.h.in and also
131        arranged for config.h to be included in the distribution, with the name
132        config.h.generic, for the benefit of those who have to compile without
133        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
135     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
136        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
137        makevp.bat for the current PCRE, using the additional files
138        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
140     6. A Windows user reported a minor discrepancy with test 2, which turned out
141        to be caused by a trailing space on an input line that had got lost in his
142        copy. The trailing space was an accident, so I've just removed it.
144     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
145        that is needed.
147     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
148        as "const" (a) because they are and (b) because it helps the PHP
149        maintainers who have recently made a script to detect big data structures
150        in the php code that should be moved to the .rodata section. I remembered
151        to update Builducptable as well, so it won't revert if ucptable.h is ever
152        re-created.
154     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
155        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
156        order to be able to cut out the UTF-8 tables in the latter when UTF-8
157        support is not required. This saves 1.5-2K of code, which is important in
158        some applications.
160        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
161        so as not to refer to the tables, even though these functions will never be
162        called when UTF-8 support is disabled. Otherwise there are problems with a
163        shared library.
165    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
167        (a) It was defining its arguments as char * instead of void *.
169        (b) It was assuming that all moves were upwards in memory; this was true
170            a long time ago when I wrote it, but is no longer the case.
172        The emulated memove() is provided for those environments that have neither
173        memmove() nor bcopy(). I didn't think anyone used it these days, but that
174        is clearly not the case, as these two bugs were recently reported.
176    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
177        and Detrail to create the HTML documentation, the .txt form of the man
178        pages, and it removes trailing spaces from listed files. It also creates
179        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
180        case, it wraps all the #defines with #ifndefs. This script should be run
181        before "make dist".
183    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
184        with Unicode property support.
186        (a) For a maximizing quantifier, if the two different cases of the
187            character were of different lengths in their UTF-8 codings (there are
188            some cases like this - I found 11), and the matching function had to
189            back up over a mixture of the two cases, it incorrectly assumed they
190            were both the same length.
192        (b) When PCRE was configured to use the heap rather than the stack for
193            recursion during matching, it was not correctly preserving the data for
194            the other case of a UTF-8 character when checking ahead for a match
195            while processing a minimizing repeat. If the check also involved
196            matching a wide character, but failed, corruption could cause an
197            erroneous result when trying to check for a repeat of the original
198            character.
200    13. Some tidying changes to the testing mechanism:
202        (a) The RunTest script now detects the internal link size and whether there
203            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
204            values substituted by "configure". (The RunGrepTest script already did
205            this for UTF-8.) The configure.ac script no longer substitutes the
206            relevant variables.
208        (b) The debugging options /B and /D in pcretest show the compiled bytecode
209            with length and offset values. This means that the output is different
210            for different internal link sizes. Test 2 is skipped for link sizes
211            other than 2 because of this, bypassing the problem. Unfortunately,
212            there was also a test in test 3 (the locale tests) that used /B and
213            failed for link sizes other than 2. Rather than cut the whole test out,
214            I have added a new /Z option to pcretest that replaces the length and
215            offset values with spaces. This is now used to make test 3 independent
216            of link size. (Test 2 will be tidied up later.)
218    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
219        segmentation fault instead of returning the appropriate error message.
221    15. In multiline mode when the newline sequence was set to "any", the pattern
222        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
223        This doesn't seem right; it now treats the CRLF combination as the line
224        ending, and so does not match in that case. It's only a pattern such as ^$
225        that would hit this one: something like ^ABC$ would have failed after \r
226        and then tried again after \r\n.
228    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
229        in an attempt to make files that differ only in their line terminators
230        compare equal. This works on Linux.
232    17. Under certain error circumstances pcregrep might try to free random memory
233        as it exited. This is now fixed, thanks to valgrind.
235    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
236        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
237        was because its rules for how to advance for /g after matching an empty
238        string at the end of a line did not allow for this case. They now check for
239        it specially.
241    20. pcretest is supposed to handle patterns and data of any length, by
242        extending its buffers when necessary. It was getting this wrong when the
243        buffer for a data line had to be extended.
245    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
246        CRLF as a newline sequence.
248    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
249        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
250        I have nevertheless tidied it up.
252    23. Added some casts to kill warnings from HP-UX ia64 compiler.
254    24. Added a man page for pcre-config.
257    Version 7.0 19-Dec-06
258    ---------------------
260     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
261        moving to gcc 4.1.1.
263     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
264        sys/time.h, which is documented as needed for this function. It doesn't
265        seem to matter on Linux, but it showed up on some releases of OS X.
267     3. It seems that there are systems where bytes whose values are greater than
268        127 match isprint() in the "C" locale. The "C" locale should be the
269        default when a C program starts up. In most systems, only ASCII printing
270        characters match isprint(). This difference caused the output from pcretest
271        to vary, making some of the tests fail. I have changed pcretest so that:
273        (a) When it is outputting text in the compiled version of a pattern, bytes
274            other than 32-126 are always shown as hex escapes.
276        (b) When it is outputting text that is a matched part of a subject string,
277            it does the same, unless a different locale has been set for the match
278            (using the /L modifier). In this case, it uses isprint() to decide.
280     4. Fixed a major bug that caused incorrect computation of the amount of memory
281        required for a compiled pattern when options that changed within the
282        pattern affected the logic of the preliminary scan that determines the
283        length. The relevant options are -x, and -i in UTF-8 mode. The result was
284        that the computed length was too small. The symptoms of this bug were
285        either the PCRE error "internal error: code overflow" from pcre_compile(),
286        or a glibc crash with a message such as "pcretest: free(): invalid next
287        size (fast)". Examples of patterns that provoked this bug (shown in
288        pcretest format) are:
290          /(?-x: )/x
291          /(?x)(?-x: \s*#\s*)/
292          /((?i)[\x{c0}])/8
293          /(?i:[\x{c0}])/8
295        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
296        is now done differently.
298     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
299        wrapper classes; (b) implement a new function in the C++ scanner that is
300        more efficient than the old way of doing things because it avoids levels of
301        recursion in the regex matching; (c) add a paragraph to the documentation
302        for the FullMatch() function.
304     6. The escape sequence \n was being treated as whatever was defined as
305        "newline". Not only was this contrary to the documentation, which states
306        that \n is character 10 (hex 0A), but it also went horribly wrong when
307        "newline" was defined as CRLF. This has been fixed.
309     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
310        was being set to -1 for the "end of line" case (supposedly a value that no
311        character can have). Though this value is never used (the check for end of
312        line is "zero bytes in current character"), it caused compiler complaints.
313        I've changed it to 0xffffffff.
315     8. In pcre_version.c, the version string was being built by a sequence of
316        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
317        string (as it is for production releases) called a macro with an empty
318        argument. The C standard says the result of this is undefined. The gcc
319        compiler treats it as an empty string (which was what was wanted) but it is
320        reported that Visual C gives an error. The source has been hacked around to
321        avoid this problem.
323     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
324        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
325        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
326        of them did).
328    10. Originally, pcretest opened its input and output without "b"; then I was
329        told that "b" was needed in some environments, so it was added for release
330        5.0 to both the input and output. (It makes no difference on Unix-like
331        systems.) Later I was told that it is wrong for the input on Windows. I've
332        now abstracted the modes into two macros, to make it easier to fiddle with
333        them, and removed "b" from the input mode under Windows.
335    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
337    12. Added -help and --help to pcretest as an official way of being reminded
338        of the options.
340    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
341        and pcrecpp.cc because they annoy compilers at high warning levels.
343    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
345    15. Fixed an occurrence of == in configure.ac that should have been = (shell
346        scripts are not C programs :-) and which was not noticed because it works
347        on Linux.
349    16. pcretest is supposed to handle any length of pattern and data line (as one
350        line or as a continued sequence of lines) by extending its input buffer if
351        necessary. This feature was broken for very long pattern lines, leading to
352        a string of junk being passed to pcre_compile() if the pattern was longer
353        than about 50K.
355    17. I have done a major re-factoring of the way pcre_compile() computes the
356        amount of memory needed for a compiled pattern. Previously, there was code
357        that made a preliminary scan of the pattern in order to do this. That was
358        OK when PCRE was new, but as the facilities have expanded, it has become
359        harder and harder to keep it in step with the real compile phase, and there
360        have been a number of bugs (see for example, 4 above). I have now found a
361        cunning way of running the real compile function in a "fake" mode that
362        enables it to compute how much memory it would need, while actually only
363        ever using a few hundred bytes of working memory and without too many
364        tests of the mode. This should make future maintenance and development
365        easier. A side effect of this work is that the limit of 200 on the nesting
366        depth of parentheses has been removed (though this was never a serious
367        limitation, I suspect). However, there is a downside: pcre_compile() now
368        runs more slowly than before (30% or more, depending on the pattern). I
369        hope this isn't a big issue. There is no effect on runtime performance.
371    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
372        newline (only possible for the last line of a file) and it was a
373        pattern that set a locale (followed by /Lsomething), pcretest crashed.
375    19. Added additional timing features to pcretest. (1) The -tm option now times
376        matching only, not compiling. (2) Both -t and -tm can be followed, as a
377        separate command line item, by a number that specifies the number of
378        repeats to use when timing. The default is 50000; this gives better
379        precision, but takes uncomfortably long for very large patterns.
381    20. Extended pcre_study() to be more clever in cases where a branch of a
382        subpattern has no definite first character. For example, (a*|b*)[cd] would
383        previously give no result from pcre_study(). Now it recognizes that the
384        first character must be a, b, c, or d.
386    21. There was an incorrect error "recursive call could loop indefinitely" if
387        a subpattern (or the entire pattern) that was being tested for matching an
388        empty string contained only one non-empty item after a nested subpattern.
389        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
390        incorrectly, because the \d was being skipped in the check.
392    22. The pcretest program now has a new pattern option /B and a command line
393        option -b, which is equivalent to adding /B to every pattern. This causes
394        it to show the compiled bytecode, without the additional information that
395        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
396        is the same as /B/I).
398    23. A new optimization is now able automatically to treat some sequences such
399        as a*b as a*+b. More specifically, if something simple (such as a character
400        or a simple class like \d) has an unlimited quantifier, and is followed by
401        something that cannot possibly match the quantified thing, the quantifier
402        is automatically "possessified".
404    24. A recursive reference to a subpattern whose number was greater than 39
405        went wrong under certain circumstances in UTF-8 mode. This bug could also
406        have affected the operation of pcre_study().
408    25. Realized that a little bit of performance could be had by replacing
409        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
411    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
413    27. Possessive quantifiers such as a++ were previously implemented by turning
414        them into atomic groups such as ($>a+). Now they have their own opcodes,
415        which improves performance. This includes the automatically created ones
416        from 23 above.
418    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
419        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
420        the first matched character to be a colon. This applied both to named and
421        numbered groups.
423    29. The ucpinternal.h header file was missing its idempotency #ifdef.
425    30. I was sent a "project" file called libpcre.a.dev which I understand makes
426        building PCRE on Windows easier, so I have included it in the distribution.
428    31. There is now a check in pcretest against a ridiculously large number being
429        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
430        loop, the loop is abandoned.
432    32. Forward references to subpatterns in conditions such as (?(2)...) where
433        subpattern 2 is defined later cause pcre_compile() to search forwards in
434        the pattern for the relevant set of parentheses. This search went wrong
435        when there were unescaped parentheses in a character class, parentheses
436        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
438    33. "Subroutine" calls and backreferences were previously restricted to
439        referencing subpatterns earlier in the regex. This restriction has now
440        been removed.
442    34. Added a number of extra features that are going to be in Perl 5.10. On the
443        whole, these are just syntactic alternatives for features that PCRE had
444        previously implemented using the Python syntax or my own invention. The
445        other formats are all retained for compatibility.
447        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
448            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
449            also .NET compatible.
451        (b) A recursion or subroutine call to a named group can now be defined as
452            (?&name) as well as (?P>name).
454        (c) A backreference to a named group can now be defined as \k<name> or
455            \k'name' as well as (?P=name). The new forms, as well as being in Perl
456            5.10, are also .NET compatible.
458        (d) A conditional reference to a named group can now use the syntax
459            (?(<name>) or (?('name') as well as (?(name).
461        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
462            groups (named and numbered) that are never evaluated inline, but can be
463            called as "subroutines" from elsewhere. In effect, the DEFINE condition
464            is always false. There may be only one alternative in such a group.
466        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
467            as the simple (?(R). The condition is true only if the most recent
468            recursion is that of the given number or name. It does not search out
469            through the entire recursion stack.
471        (g) The escape \gN or \g{N} has been added, where N is a positive or
472            negative number, specifying an absolute or relative reference.
474    35. Tidied to get rid of some further signed/unsigned compiler warnings and
475        some "unreachable code" warnings.
477    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
478        things, this adds five new scripts.
480    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
481        There were also incompatibilities regarding the handling of \Q..\E inside
482        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
483        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
485    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
486        matches an empty string, and forcibly breaks the loop. There were bugs in
487        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
488        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
489        separate and independent bugs (that affected different cases) have been
490        fixed.
492    39. Refactored the code to abolish the use of different opcodes for small
493        capturing bracket numbers. This is a tidy that I avoided doing when I
494        removed the limit on the number of capturing brackets for 3.5 back in 2001.
495        The new approach is not only tidier, it makes it possible to reduce the
496        memory needed to fix the previous bug (38).
498    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
499        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
500        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
501        mode.
503    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
504        report.
506    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
507        copy construction and assignment in the C++ wrapper.
509    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
510        couple of bugs that could have given wrong results in the "--newline=crlf"
511        case.
513    44. Added a number of casts and did some reorganization of signed/unsigned int
514        variables following suggestions from Dair Grant. Also renamed the variable
515        "this" as "item" because it is a C++ keyword.
517    45. Arranged for dftables to add
519          #include "pcre_internal.h"
521        to pcre_chartables.c because without it, gcc 4.x may remove the array
522        definition from the final binary if PCRE is built into a static library and
523        dead code stripping is activated.
525    46. For an unanchored pattern, if a match attempt fails at the start of a
526        newline sequence, and the newline setting is CRLF or ANY, and the next two
527        characters are CRLF, advance by two characters instead of one.
530    Version 6.7 04-Jul-06
531    ---------------------
533     1. In order to handle tests when input lines are enormously long, pcretest has
534        been re-factored so that it automatically extends its buffers when
535        necessary. The code is crude, but this _is_ just a test program. The
536        default size has been increased from 32K to 50K.
538     2. The code in pcre_study() was using the value of the re argument before
539        testing it for NULL. (Of course, in any sensible call of the function, it
540        won't be NULL.)
542     3. The memmove() emulation function in pcre_internal.h, which is used on
543        systems that lack both memmove() and bcopy() - that is, hardly ever -
544        was missing a "static" storage class specifier.
546     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
547        containing an extended class (one that cannot be represented by a bitmap
548        because it contains high-valued characters or Unicode property items, e.g.
549        [\pZ]). Almost always one would set UTF-8 mode when processing such a
550        pattern, but PCRE should not loop if you do not (it no longer does).
551        [Detail: two cases were found: (a) a repeated subpattern containing an
552        extended class; (b) a recursive reference to a subpattern that followed a
553        previous extended class. It wasn't skipping over the extended class
554        correctly when UTF-8 mode was not set.]
556     5. A negated single-character class was not being recognized as fixed-length
557        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
558        compile error "lookbehind assertion is not fixed length".
560     6. The RunPerlTest auxiliary script was showing an unexpected difference
561        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
562        write a Perl script that can interpret lines of an input file either as
563        byte characters or as UTF-8, which is what "perltest" was being required to
564        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
565        can't do is switch easily at run time between having the "use utf8;" pragma
566        or not. In the end, I fudged it by using the RunPerlTest script to insert
567        "use utf8;" explicitly for the UTF-8 tests.
569     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
570        the end of the subject string, contrary to the documentation and to what
571        Perl does. This was true of both matching functions. Now it matches only at
572        the start of the subject and immediately after *internal* newlines.
574     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
575        a pointer to an int instead of a pointer to an unsigned long int. This
576        caused problems on 64-bit systems.
578     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
579        instance of the 'standard' template library not being so standard".
581    10. There was no check on the number of named subpatterns nor the maximum
582        length of a subpattern name. The product of these values is used to compute
583        the size of the memory block for a compiled pattern. By supplying a very
584        long subpattern name and a large number of named subpatterns, the size
585        computation could be caused to overflow. This is now prevented by limiting
586        the length of names to 32 characters, and the number of named subpatterns
587        to 10,000.
589    11. Subpatterns that are repeated with specific counts have to be replicated in
590        the compiled pattern. The size of memory for this was computed from the
591        length of the subpattern and the repeat count. The latter is limited to
592        65535, but there was no limit on the former, meaning that integer overflow
593        could in principle occur. The compiled length of a repeated subpattern is
594        now limited to 30,000 bytes in order to prevent this.
596    12. Added the optional facility to have named substrings with the same name.
598    13. Added the ability to use a named substring as a condition, using the
599        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
600        are numbers (not recommended). Forward references are permitted.
602    14. Added forward references in named backreferences (if you see what I mean).
604    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
605        pattern could run off the end of the subject. For example, the pattern
606        "(?s)(.{1,5})"8 did this with the subject "ab".
608    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
609        PCRE_CASELESS was set when matching characters that were quantified with ?
610        or *.
612    17. A character class other than a single negated character that had a minimum
613        but no maximum quantifier - for example [ab]{6,} - was not handled
614        correctly by pce_dfa_exec(). It would match only one character.
616    18. A valid (though odd) pattern that looked like a POSIX character
617        class but used an invalid character after [ (for example [[,abc,]]) caused
618        pcre_compile() to give the error "Failed: internal error: code overflow" or
619        in some cases to crash with a glibc free() error. This could even happen if
620        the pattern terminated after [[ but there just happened to be a sequence of
621        letters, a binary zero, and a closing ] in the memory that followed.
623    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
624        over the years. Originally (before any Unicode support), just the bottom 8
625        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
626        output from "man perlunicode" includes this:
628          The regular expression compiler produces polymorphic opcodes.  That
629          is, the pattern adapts to the data and automatically switches to
630          the Unicode character scheme when presented with Unicode data--or
631          instead uses a traditional byte scheme when presented with byte
632          data.
634        Sadly, a wide octal escape does not cause a switch, and in a string with
635        no other multibyte characters, these octal escapes are treated as before.
636        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
637        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
638        Unicode string.
640        I have not perpetrated such confusion in PCRE. Up till now, it took just
641        the bottom 8 bits, as in old Perl. I have now made octal escapes with
642        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
643        translate to the appropriate multibyte character.
645    29. Applied some refactoring to reduce the number of warnings from Microsoft
646        and Borland compilers. This has included removing the fudge introduced
647        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
648        a warning about an unused variable.
650    21. PCRE has not included VT (character 0x0b) in the set of whitespace
651        characters since release 4.0, because Perl (from release 5.004) does not.
652        [Or at least, is documented not to: some releases seem to be in conflict
653        with the documentation.] However, when a pattern was studied with
654        pcre_study() and all its branches started with \s, PCRE still included VT
655        as a possible starting character. Of course, this did no harm; it just
656        caused an unnecessary match attempt.
658    22. Removed a now-redundant internal flag bit that recorded the fact that case
659        dependency changed within the pattern. This was once needed for "required
660        byte" processing, but is no longer used. This recovers a now-scarce options
661        bit. Also moved the least significant internal flag bit to the most-
662        significant bit of the word, which was not previously used (hangover from
663        the days when it was an int rather than a uint) to free up another bit for
664        the future.
666    23. Added support for CRLF line endings as well as CR and LF. As well as the
667        default being selectable at build time, it can now be changed at runtime
668        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
669        specify that it is scanning data with non-default line endings.
671    24. Changed the definition of CXXLINK to make it agree with the definition of
672        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
674    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
675        recursions. This makes a big different to stack usage for some patterns.
677    26. If a subpattern containing a named recursion or subroutine reference such
678        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
679        the space required for the compiled pattern went wrong and gave too small a
680        value. Depending on the environment, this could lead to "Failed: internal
681        error: code overflow at offset 49" or "glibc detected double free or
682        corruption" errors.
684    27. Applied patches from Google (a) to support the new newline modes and (b) to
685        advance over multibyte UTF-8 characters in GlobalReplace.
687    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
688        difference for some implementation of PCRE in some Windows version.
690    29. Added some extra testing facilities to pcretest:
692        \q<number>   in a data line sets the "match limit" value
693        \Q<number>   in a data line sets the "match recursion limt" value
694        -S <number>  sets the stack size, where <number> is in megabytes
696        The -S option isn't available for Windows.
699    Version 6.6 06-Feb-06
700    ---------------------
702     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
703        in pcreposix.h. I have copied the definition from pcre.h.
705     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
706        because pcre.h is no longer a built file.
708     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
709        not normally included in the compiled code.
712    Version 6.5 01-Feb-06
713    ---------------------
715     1. When using the partial match feature with pcre_dfa_exec(), it was not
716        anchoring the second and subsequent partial matches at the new starting
717        point. This could lead to incorrect results. For example, with the pattern
718        /1234/, partially matching against "123" and then "a4" gave a match.
720     2. Changes to pcregrep:
722        (a) All non-match returns from pcre_exec() were being treated as failures
723            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
724            error message is output. Some extra information is given for the
725            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
726            probably the only errors that are likely to be caused by users (by
727            specifying a regex that has nested indefinite repeats, for instance).
728            If there are more than 20 of these errors, pcregrep is abandoned.
730        (b) A binary zero was treated as data while matching, but terminated the
731            output line if it was written out. This has been fixed: binary zeroes
732            are now no different to any other data bytes.
734        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
735            used to set a locale for matching. The --locale=xxxx long option has
736            been added (no short equivalent) to specify a locale explicitly on the
737            pcregrep command, overriding the environment variables.
739        (d) When -B was used with -n, some line numbers in the output were one less
740            than they should have been.
742        (e) Added the -o (--only-matching) option.
744        (f) If -A or -C was used with -c (count only), some lines of context were
745            accidentally printed for the final match.
747        (g) Added the -H (--with-filename) option.
749        (h) The combination of options -rh failed to suppress file names for files
750            that were found from directory arguments.
752        (i) Added the -D (--devices) and -d (--directories) options.
754        (j) Added the -F (--fixed-strings) option.
756        (k) Allow "-" to be used as a file name for -f as well as for a data file.
758        (l) Added the --colo(u)r option.
760        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
761            is not present by default.
763     3. A nasty bug was discovered in the handling of recursive patterns, that is,
764        items such as (?R) or (?1), when the recursion could match a number of
765        alternatives. If it matched one of the alternatives, but subsequently,
766        outside the recursion, there was a failure, the code tried to back up into
767        the recursion. However, because of the way PCRE is implemented, this is not
768        possible, and the result was an incorrect result from the match.
770        In order to prevent this happening, the specification of recursion has
771        been changed so that all such subpatterns are automatically treated as
772        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
774     4. I had overlooked the fact that, in some locales, there are characters for
775        which isalpha() is true but neither isupper() nor islower() are true. In
776        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
777        and ordfeminine) are like this. This affected the treatment of \w and \W
778        when they appeared in character classes, but not when they appeared outside
779        a character class. The bit map for "word" characters is now created
780        separately from the results of isalnum() instead of just taking it from the
781        upper, lower, and digit maps. (Plus the underscore character, of course.)
783     5. The above bug also affected the handling of POSIX character classes such as
784        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
785        permanent tables. Instead, the bit maps for such a class were previously
786        created as the appropriate unions of the upper, lower, and digit bitmaps.
787        Now they are created by subtraction from the [[:word:]] class, which has
788        its own bitmap.
790     6. The [[:blank:]] character class matches horizontal, but not vertical space.
791        It is created by subtracting the vertical space characters (\x09, \x0a,
792        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
793        subtraction was done in the overall bitmap for a character class, meaning
794        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
795        be recognized. This bug has been fixed.
797     7. Patches from the folks at Google:
799          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
800          real life, but is still worth protecting against".
802          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
803          regular expressions".
805          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
806          have it.
808          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
809          "configure" and the latter not, in order to fix a problem somebody had
810          with compiling the Arg class on HP-UX.
812          (e) Improve the error-handling of the C++ wrapper a little bit.
814          (f) New tests for checking recursion limiting.
816     8. The pcre_memmove() function, which is used only if the environment does not
817        have a standard memmove() function (and is therefore rarely compiled),
818        contained two bugs: (a) use of int instead of size_t, and (b) it was not
819        returning a result (though PCRE never actually uses the result).
821     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
822        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
823        returned instead of calling malloc() with an overflowing number that would
824        most likely cause subsequent chaos.
826    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
828    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
829        with this option is matched, the nmatch and pmatch options of regexec() are
830        ignored.
832    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
833        provided in case anyone wants to the the POSIX interface with UTF-8
834        strings.
836    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
837        C++ linking (needed for some HP-UX environments).
839    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
840        (unused parameter) and in the pcre_printint() function (omitted "default"
841        switch label when the default is to do nothing).
843    15. Added some code to make it possible, when PCRE is compiled as a C++
844        library, to replace subject pointers for pcre_exec() with a smart pointer
845        class, thus making it possible to process discontinuous strings.
847    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
848        much the same function. They were added by different people who were trying
849        to make PCRE easy to compile on non-Unix systems. It has been suggested
850        that PCRE_EXPORT be abolished now that there is more automatic apparatus
851        for compiling on Windows systems. I have therefore replaced it with
852        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
853        defaults to "extern" for C or "extern C" for C++, which works fine on
854        Unix-like systems. It is now possible to override the value of PCRE_DATA_
855        SCOPE with something explicit in config.h. In addition:
857        (a) pcreposix.h still had just "extern" instead of either of these macros;
858            I have replaced it with PCRE_DATA_SCOPE.
860        (b) Functions such as _pcre_xclass(), which are internal to the library,
861            but external in the C sense, all had PCRE_EXPORT in their definitions.
862            This is apparently wrong for the Windows case, so I have removed it.
863            (It makes no difference on Unix-like systems.)
865    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
866        of recursive calls to match(). This is different to MATCH_LIMIT because
867        that limits the total number of calls to match(), not all of which increase
868        the depth of recursion. Limiting the recursion depth limits the amount of
869        stack (or heap if NO_RECURSE is set) that is used. The default can be set
870        when PCRE is compiled, and changed at run time. A patch from Google adds
871        this functionality to the C++ interface.
873    18. Changes to the handling of Unicode character properties:
875        (a) Updated the table to Unicode 4.1.0.
877        (b) Recognize characters that are not in the table as "Cn" (undefined).
879        (c) I revised the way the table is implemented to a much improved format
880            which includes recognition of ranges. It now supports the ranges that
881            are defined in UnicodeData.txt, and it also amalgamates other
882            characters into ranges. This has reduced the number of entries in the
883            table from around 16,000 to around 3,000, thus reducing its size
884            considerably. I realized I did not need to use a tree structure after
885            all - a binary chop search is just as efficient. Having reduced the
886            number of entries, I extended their size from 6 bytes to 8 bytes to
887            allow for more data.
889        (d) Added support for Unicode script names via properties such as \p{Han}.
891    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
892        matching that character.
894    20. When matching a repeated Unicode property with a minimum greater than zero,
895        (for example \pL{2,}), PCRE could look past the end of the subject if it
896        reached it while seeking the minimum number of characters. This could
897        happen only if some of the characters were more than one byte long, because
898        there is a check for at least the minimum number of bytes.
900    21. Refactored the implementation of \p and \P so as to be more general, to
901        allow for more different types of property in future. This has changed the
902        compiled form incompatibly. Anybody with saved compiled patterns that use
903        \p or \P will have to recompile them.
905    22. Added "Any" and "L&" to the supported property types.
907    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
908        but give a compile time error if the value is greater than 0xff.
910    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
911        accidentally not being installed or uninstalled.
913    25. The pcre.h file was built from pcre.h.in, but the only changes that were
914        made were to insert the current release number. This seemed silly, because
915        it made things harder for people building PCRE on systems that don't run
916        "configure". I have turned pcre.h into a distributed file, no longer built
917        by "configure", with the version identification directly included. There is
918        no longer a pcre.h.in file.
920        However, this change necessitated a change to the pcre-config script as
921        well. It is built from pcre-config.in, and one of the substitutions was the
922        release number. I have updated configure.ac so that ./configure now finds
923        the release number by grepping pcre.h.
925    26. Added the ability to run the tests under valgrind.
928    Version 6.4 05-Sep-05
929    ---------------------
931     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
932        "--" to be printed when multiple files were scanned, even when none of the
933        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
934        consider it to be a bug, and have restored the previous behaviour.
936     2. A couple of code tidies to get rid of compiler warnings.
938     3. The pcretest program used to cheat by referring to symbols in the library
939        whose names begin with _pcre_. These are internal symbols that are not
940        really supposed to be visible externally, and in some environments it is
941        possible to suppress them. The cheating is now confined to including
942        certain files from the library's source, which is a bit cleaner.
944     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
945        file's purpose clearer.
947     5. Reorganized pcre_ucp_findchar().
950  Version 6.3 15-Aug-05  Version 6.3 15-Aug-05
951  ---------------------  ---------------------

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