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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.3 09-Aug-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.
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.
35     6. ESC_K was left out of the EBCDIC table.
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.
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.
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.
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.
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.
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.
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".
91    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
92        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
94    14. Optimized (?!) to (*FAIL).
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.
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.
106    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
107        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
109    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
110        caused an overrun.
112    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
113        something other than just ASCII characters) inside a group that had an
114        unlimited repeat caused a loop at compile time (while checking to see
115        whether the group could match an empty string).
117    20. Debugging a pattern containing \p or \P could cause a crash. For example,
118        [\P{Any}] did so. (Error in the code for printing property names.)
120    21. An orphan \E inside a character class could cause a crash.
122    22. A repeated capturing bracket such as (A)? could cause a wild memory
123        reference during compilation.
125    23. There are several functions in pcre_compile() that scan along a compiled
126        expression for various reasons (e.g. to see if it's fixed length for look
127        behind). There were bugs in these functions when a repeated \p or \P was
128        present in the pattern. These operators have additional parameters compared
129        with \d, etc, and these were not being taken into account when moving along
130        the compiled data. Specifically:
132        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
133            length.
135        (b) An item such as \pL+ within a repeated group could cause crashes or
136            loops.
138        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
139            "reference to non-existent subpattern" error.
142    Version 7.2 19-Jun-07
143    ---------------------
145     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
146        which is apparently normally available under Windows.
148     2. Re-jig the pcregrep tests with different newline settings in an attempt
149        to make them independent of the local environment's newline setting.
151     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
153     4. Some of the "internals" tests were previously cut out when the link size
154        was not 2, because the output contained actual offsets. The recent new
155        "Z" feature of pcretest means that these can be cut out, making the tests
156        usable with all link sizes.
158     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
159        stack recursion. This gives a massive performance boost under BSD, but just
160        a small improvement under Linux. However, it saves one field in the frame
161        in all cases.
163     6. Added more features from the forthcoming Perl 5.10:
165        (a) (?-n) (where n is a string of digits) is a relative subroutine or
166            recursion call. It refers to the nth most recently opened parentheses.
168        (b) (?+n) is also a relative subroutine call; it refers to the nth next
169            to be opened parentheses.
171        (c) Conditions that refer to capturing parentheses can be specified
172            relatively, for example, (?(-2)... or (?(+3)...
174        (d) \K resets the start of the current match so that everything before
175            is not part of it.
177        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
179        (f) \g{name} is another synonym - part of Perl 5.10's unification of
180            reference syntax.
182        (g) (?| introduces a group in which the numbering of parentheses in each
183            alternative starts with the same number.
185        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
187     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
190     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
191        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
192        for detecting groups that can match an empty string.
194     9. A pattern with a very large number of alternatives (more than several
195        hundred) was running out of internal workspace during the pre-compile
196        phase, where pcre_compile() figures out how much memory will be needed. A
197        bit of new cunning has reduced the workspace needed for groups with
198        alternatives. The 1000-alternative test pattern now uses 12 bytes of
199        workspace instead of running out of the 4096 that are available.
201    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
203    11. Applied patch from Google to remove an optimization that didn't quite work.
204        The report of the bug said:
206          pcrecpp::RE("a*").FullMatch("aaa") matches, while
207          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
208          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
210    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
211        it matched the wrong number of bytes.
214    Version 7.1 24-Apr-07
215    ---------------------
217     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
218        that is more "standard", making use of automake and other Autotools. There
219        is some re-arrangement of the files and adjustment of comments consequent
220        on this.
222     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
223        for recursive directory scanning broke on some systems because the files
224        are not scanned in any specific order and on different systems the order
225        was different. A call to "sort" has been inserted into RunGrepTest for the
226        approprate test as a short-term fix. In the longer term there may be an
227        alternative.
229     3. I had an email from Eric Raymond about problems translating some of PCRE's
230        man pages to HTML (despite the fact that I distribute HTML pages, some
231        people do their own conversions for various reasons). The problems
232        concerned the use of low-level troff macros .br and .in. I have therefore
233        removed all such uses from the man pages (some were redundant, some could
234        be replaced by .nf/.fi pairs). The 132html script that I use to generate
235        HTML has been updated to handle .nf/.fi and to complain if it encounters
236        .br or .in.
238     4. Updated comments in configure.ac that get placed in config.h.in and also
239        arranged for config.h to be included in the distribution, with the name
240        config.h.generic, for the benefit of those who have to compile without
241        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
243     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
244        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
245        makevp.bat for the current PCRE, using the additional files
246        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
248     6. A Windows user reported a minor discrepancy with test 2, which turned out
249        to be caused by a trailing space on an input line that had got lost in his
250        copy. The trailing space was an accident, so I've just removed it.
252     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
253        that is needed.
255     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
256        as "const" (a) because they are and (b) because it helps the PHP
257        maintainers who have recently made a script to detect big data structures
258        in the php code that should be moved to the .rodata section. I remembered
259        to update Builducptable as well, so it won't revert if ucptable.h is ever
260        re-created.
262     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
263        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
264        order to be able to cut out the UTF-8 tables in the latter when UTF-8
265        support is not required. This saves 1.5-2K of code, which is important in
266        some applications.
268        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
269        so as not to refer to the tables, even though these functions will never be
270        called when UTF-8 support is disabled. Otherwise there are problems with a
271        shared library.
273    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
275        (a) It was defining its arguments as char * instead of void *.
277        (b) It was assuming that all moves were upwards in memory; this was true
278            a long time ago when I wrote it, but is no longer the case.
280        The emulated memove() is provided for those environments that have neither
281        memmove() nor bcopy(). I didn't think anyone used it these days, but that
282        is clearly not the case, as these two bugs were recently reported.
284    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
285        and Detrail to create the HTML documentation, the .txt form of the man
286        pages, and it removes trailing spaces from listed files. It also creates
287        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
288        case, it wraps all the #defines with #ifndefs. This script should be run
289        before "make dist".
291    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
292        with Unicode property support.
294        (a) For a maximizing quantifier, if the two different cases of the
295            character were of different lengths in their UTF-8 codings (there are
296            some cases like this - I found 11), and the matching function had to
297            back up over a mixture of the two cases, it incorrectly assumed they
298            were both the same length.
300        (b) When PCRE was configured to use the heap rather than the stack for
301            recursion during matching, it was not correctly preserving the data for
302            the other case of a UTF-8 character when checking ahead for a match
303            while processing a minimizing repeat. If the check also involved
304            matching a wide character, but failed, corruption could cause an
305            erroneous result when trying to check for a repeat of the original
306            character.
308    13. Some tidying changes to the testing mechanism:
310        (a) The RunTest script now detects the internal link size and whether there
311            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
312            values substituted by "configure". (The RunGrepTest script already did
313            this for UTF-8.) The configure.ac script no longer substitutes the
314            relevant variables.
316        (b) The debugging options /B and /D in pcretest show the compiled bytecode
317            with length and offset values. This means that the output is different
318            for different internal link sizes. Test 2 is skipped for link sizes
319            other than 2 because of this, bypassing the problem. Unfortunately,
320            there was also a test in test 3 (the locale tests) that used /B and
321            failed for link sizes other than 2. Rather than cut the whole test out,
322            I have added a new /Z option to pcretest that replaces the length and
323            offset values with spaces. This is now used to make test 3 independent
324            of link size. (Test 2 will be tidied up later.)
326    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
327        segmentation fault instead of returning the appropriate error message.
329    15. In multiline mode when the newline sequence was set to "any", the pattern
330        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
331        This doesn't seem right; it now treats the CRLF combination as the line
332        ending, and so does not match in that case. It's only a pattern such as ^$
333        that would hit this one: something like ^ABC$ would have failed after \r
334        and then tried again after \r\n.
336    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
337        in an attempt to make files that differ only in their line terminators
338        compare equal. This works on Linux.
340    17. Under certain error circumstances pcregrep might try to free random memory
341        as it exited. This is now fixed, thanks to valgrind.
343    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
344        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
345        was because its rules for how to advance for /g after matching an empty
346        string at the end of a line did not allow for this case. They now check for
347        it specially.
349    20. pcretest is supposed to handle patterns and data of any length, by
350        extending its buffers when necessary. It was getting this wrong when the
351        buffer for a data line had to be extended.
353    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
354        CRLF as a newline sequence.
356    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
357        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
358        I have nevertheless tidied it up.
360    23. Added some casts to kill warnings from HP-UX ia64 compiler.
362    24. Added a man page for pcre-config.
365    Version 7.0 19-Dec-06
366    ---------------------
368     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
369        moving to gcc 4.1.1.
371     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
372        sys/time.h, which is documented as needed for this function. It doesn't
373        seem to matter on Linux, but it showed up on some releases of OS X.
375     3. It seems that there are systems where bytes whose values are greater than
376        127 match isprint() in the "C" locale. The "C" locale should be the
377        default when a C program starts up. In most systems, only ASCII printing
378        characters match isprint(). This difference caused the output from pcretest
379        to vary, making some of the tests fail. I have changed pcretest so that:
381        (a) When it is outputting text in the compiled version of a pattern, bytes
382            other than 32-126 are always shown as hex escapes.
384        (b) When it is outputting text that is a matched part of a subject string,
385            it does the same, unless a different locale has been set for the match
386            (using the /L modifier). In this case, it uses isprint() to decide.
388     4. Fixed a major bug that caused incorrect computation of the amount of memory
389        required for a compiled pattern when options that changed within the
390        pattern affected the logic of the preliminary scan that determines the
391        length. The relevant options are -x, and -i in UTF-8 mode. The result was
392        that the computed length was too small. The symptoms of this bug were
393        either the PCRE error "internal error: code overflow" from pcre_compile(),
394        or a glibc crash with a message such as "pcretest: free(): invalid next
395        size (fast)". Examples of patterns that provoked this bug (shown in
396        pcretest format) are:
398          /(?-x: )/x
399          /(?x)(?-x: \s*#\s*)/
400          /((?i)[\x{c0}])/8
401          /(?i:[\x{c0}])/8
403        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
404        is now done differently.
406     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
407        wrapper classes; (b) implement a new function in the C++ scanner that is
408        more efficient than the old way of doing things because it avoids levels of
409        recursion in the regex matching; (c) add a paragraph to the documentation
410        for the FullMatch() function.
412     6. The escape sequence \n was being treated as whatever was defined as
413        "newline". Not only was this contrary to the documentation, which states
414        that \n is character 10 (hex 0A), but it also went horribly wrong when
415        "newline" was defined as CRLF. This has been fixed.
417     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
418        was being set to -1 for the "end of line" case (supposedly a value that no
419        character can have). Though this value is never used (the check for end of
420        line is "zero bytes in current character"), it caused compiler complaints.
421        I've changed it to 0xffffffff.
423     8. In pcre_version.c, the version string was being built by a sequence of
424        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
425        string (as it is for production releases) called a macro with an empty
426        argument. The C standard says the result of this is undefined. The gcc
427        compiler treats it as an empty string (which was what was wanted) but it is
428        reported that Visual C gives an error. The source has been hacked around to
429        avoid this problem.
431     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
432        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
433        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
434        of them did).
436    10. Originally, pcretest opened its input and output without "b"; then I was
437        told that "b" was needed in some environments, so it was added for release
438        5.0 to both the input and output. (It makes no difference on Unix-like
439        systems.) Later I was told that it is wrong for the input on Windows. I've
440        now abstracted the modes into two macros, to make it easier to fiddle with
441        them, and removed "b" from the input mode under Windows.
443    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
445    12. Added -help and --help to pcretest as an official way of being reminded
446        of the options.
448    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
449        and pcrecpp.cc because they annoy compilers at high warning levels.
451    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
453    15. Fixed an occurrence of == in configure.ac that should have been = (shell
454        scripts are not C programs :-) and which was not noticed because it works
455        on Linux.
457    16. pcretest is supposed to handle any length of pattern and data line (as one
458        line or as a continued sequence of lines) by extending its input buffer if
459        necessary. This feature was broken for very long pattern lines, leading to
460        a string of junk being passed to pcre_compile() if the pattern was longer
461        than about 50K.
463    17. I have done a major re-factoring of the way pcre_compile() computes the
464        amount of memory needed for a compiled pattern. Previously, there was code
465        that made a preliminary scan of the pattern in order to do this. That was
466        OK when PCRE was new, but as the facilities have expanded, it has become
467        harder and harder to keep it in step with the real compile phase, and there
468        have been a number of bugs (see for example, 4 above). I have now found a
469        cunning way of running the real compile function in a "fake" mode that
470        enables it to compute how much memory it would need, while actually only
471        ever using a few hundred bytes of working memory and without too many
472        tests of the mode. This should make future maintenance and development
473        easier. A side effect of this work is that the limit of 200 on the nesting
474        depth of parentheses has been removed (though this was never a serious
475        limitation, I suspect). However, there is a downside: pcre_compile() now
476        runs more slowly than before (30% or more, depending on the pattern). I
477        hope this isn't a big issue. There is no effect on runtime performance.
479    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
480        newline (only possible for the last line of a file) and it was a
481        pattern that set a locale (followed by /Lsomething), pcretest crashed.
483    19. Added additional timing features to pcretest. (1) The -tm option now times
484        matching only, not compiling. (2) Both -t and -tm can be followed, as a
485        separate command line item, by a number that specifies the number of
486        repeats to use when timing. The default is 50000; this gives better
487        precision, but takes uncomfortably long for very large patterns.
489    20. Extended pcre_study() to be more clever in cases where a branch of a
490        subpattern has no definite first character. For example, (a*|b*)[cd] would
491        previously give no result from pcre_study(). Now it recognizes that the
492        first character must be a, b, c, or d.
494    21. There was an incorrect error "recursive call could loop indefinitely" if
495        a subpattern (or the entire pattern) that was being tested for matching an
496        empty string contained only one non-empty item after a nested subpattern.
497        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
498        incorrectly, because the \d was being skipped in the check.
500    22. The pcretest program now has a new pattern option /B and a command line
501        option -b, which is equivalent to adding /B to every pattern. This causes
502        it to show the compiled bytecode, without the additional information that
503        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
504        is the same as /B/I).
506    23. A new optimization is now able automatically to treat some sequences such
507        as a*b as a*+b. More specifically, if something simple (such as a character
508        or a simple class like \d) has an unlimited quantifier, and is followed by
509        something that cannot possibly match the quantified thing, the quantifier
510        is automatically "possessified".
512    24. A recursive reference to a subpattern whose number was greater than 39
513        went wrong under certain circumstances in UTF-8 mode. This bug could also
514        have affected the operation of pcre_study().
516    25. Realized that a little bit of performance could be had by replacing
517        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
519    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
521    27. Possessive quantifiers such as a++ were previously implemented by turning
522        them into atomic groups such as ($>a+). Now they have their own opcodes,
523        which improves performance. This includes the automatically created ones
524        from 23 above.
526    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
527        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
528        the first matched character to be a colon. This applied both to named and
529        numbered groups.
531    29. The ucpinternal.h header file was missing its idempotency #ifdef.
533    30. I was sent a "project" file called libpcre.a.dev which I understand makes
534        building PCRE on Windows easier, so I have included it in the distribution.
536    31. There is now a check in pcretest against a ridiculously large number being
537        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
538        loop, the loop is abandoned.
540    32. Forward references to subpatterns in conditions such as (?(2)...) where
541        subpattern 2 is defined later cause pcre_compile() to search forwards in
542        the pattern for the relevant set of parentheses. This search went wrong
543        when there were unescaped parentheses in a character class, parentheses
544        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
546    33. "Subroutine" calls and backreferences were previously restricted to
547        referencing subpatterns earlier in the regex. This restriction has now
548        been removed.
550    34. Added a number of extra features that are going to be in Perl 5.10. On the
551        whole, these are just syntactic alternatives for features that PCRE had
552        previously implemented using the Python syntax or my own invention. The
553        other formats are all retained for compatibility.
555        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
556            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
557            also .NET compatible.
559        (b) A recursion or subroutine call to a named group can now be defined as
560            (?&name) as well as (?P>name).
562        (c) A backreference to a named group can now be defined as \k<name> or
563            \k'name' as well as (?P=name). The new forms, as well as being in Perl
564            5.10, are also .NET compatible.
566        (d) A conditional reference to a named group can now use the syntax
567            (?(<name>) or (?('name') as well as (?(name).
569        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
570            groups (named and numbered) that are never evaluated inline, but can be
571            called as "subroutines" from elsewhere. In effect, the DEFINE condition
572            is always false. There may be only one alternative in such a group.
574        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
575            as the simple (?(R). The condition is true only if the most recent
576            recursion is that of the given number or name. It does not search out
577            through the entire recursion stack.
579        (g) The escape \gN or \g{N} has been added, where N is a positive or
580            negative number, specifying an absolute or relative reference.
582    35. Tidied to get rid of some further signed/unsigned compiler warnings and
583        some "unreachable code" warnings.
585    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
586        things, this adds five new scripts.
588    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
589        There were also incompatibilities regarding the handling of \Q..\E inside
590        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
591        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
593    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
594        matches an empty string, and forcibly breaks the loop. There were bugs in
595        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
596        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
597        separate and independent bugs (that affected different cases) have been
598        fixed.
600    39. Refactored the code to abolish the use of different opcodes for small
601        capturing bracket numbers. This is a tidy that I avoided doing when I
602        removed the limit on the number of capturing brackets for 3.5 back in 2001.
603        The new approach is not only tidier, it makes it possible to reduce the
604        memory needed to fix the previous bug (38).
606    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
607        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
608        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
609        mode.
611    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
612        report.
614    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
615        copy construction and assignment in the C++ wrapper.
617    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
618        couple of bugs that could have given wrong results in the "--newline=crlf"
619        case.
621    44. Added a number of casts and did some reorganization of signed/unsigned int
622        variables following suggestions from Dair Grant. Also renamed the variable
623        "this" as "item" because it is a C++ keyword.
625    45. Arranged for dftables to add
627          #include "pcre_internal.h"
629        to pcre_chartables.c because without it, gcc 4.x may remove the array
630        definition from the final binary if PCRE is built into a static library and
631        dead code stripping is activated.
633    46. For an unanchored pattern, if a match attempt fails at the start of a
634        newline sequence, and the newline setting is CRLF or ANY, and the next two
635        characters are CRLF, advance by two characters instead of one.
638    Version 6.7 04-Jul-06
639    ---------------------
641     1. In order to handle tests when input lines are enormously long, pcretest has
642        been re-factored so that it automatically extends its buffers when
643        necessary. The code is crude, but this _is_ just a test program. The
644        default size has been increased from 32K to 50K.
646     2. The code in pcre_study() was using the value of the re argument before
647        testing it for NULL. (Of course, in any sensible call of the function, it
648        won't be NULL.)
650     3. The memmove() emulation function in pcre_internal.h, which is used on
651        systems that lack both memmove() and bcopy() - that is, hardly ever -
652        was missing a "static" storage class specifier.
654     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
655        containing an extended class (one that cannot be represented by a bitmap
656        because it contains high-valued characters or Unicode property items, e.g.
657        [\pZ]). Almost always one would set UTF-8 mode when processing such a
658        pattern, but PCRE should not loop if you do not (it no longer does).
659        [Detail: two cases were found: (a) a repeated subpattern containing an
660        extended class; (b) a recursive reference to a subpattern that followed a
661        previous extended class. It wasn't skipping over the extended class
662        correctly when UTF-8 mode was not set.]
664     5. A negated single-character class was not being recognized as fixed-length
665        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
666        compile error "lookbehind assertion is not fixed length".
668     6. The RunPerlTest auxiliary script was showing an unexpected difference
669        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
670        write a Perl script that can interpret lines of an input file either as
671        byte characters or as UTF-8, which is what "perltest" was being required to
672        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
673        can't do is switch easily at run time between having the "use utf8;" pragma
674        or not. In the end, I fudged it by using the RunPerlTest script to insert
675        "use utf8;" explicitly for the UTF-8 tests.
677     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
678        the end of the subject string, contrary to the documentation and to what
679        Perl does. This was true of both matching functions. Now it matches only at
680        the start of the subject and immediately after *internal* newlines.
682     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
683        a pointer to an int instead of a pointer to an unsigned long int. This
684        caused problems on 64-bit systems.
686     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
687        instance of the 'standard' template library not being so standard".
689    10. There was no check on the number of named subpatterns nor the maximum
690        length of a subpattern name. The product of these values is used to compute
691        the size of the memory block for a compiled pattern. By supplying a very
692        long subpattern name and a large number of named subpatterns, the size
693        computation could be caused to overflow. This is now prevented by limiting
694        the length of names to 32 characters, and the number of named subpatterns
695        to 10,000.
697    11. Subpatterns that are repeated with specific counts have to be replicated in
698        the compiled pattern. The size of memory for this was computed from the
699        length of the subpattern and the repeat count. The latter is limited to
700        65535, but there was no limit on the former, meaning that integer overflow
701        could in principle occur. The compiled length of a repeated subpattern is
702        now limited to 30,000 bytes in order to prevent this.
704    12. Added the optional facility to have named substrings with the same name.
706    13. Added the ability to use a named substring as a condition, using the
707        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
708        are numbers (not recommended). Forward references are permitted.
710    14. Added forward references in named backreferences (if you see what I mean).
712    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
713        pattern could run off the end of the subject. For example, the pattern
714        "(?s)(.{1,5})"8 did this with the subject "ab".
716    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
717        PCRE_CASELESS was set when matching characters that were quantified with ?
718        or *.
720    17. A character class other than a single negated character that had a minimum
721        but no maximum quantifier - for example [ab]{6,} - was not handled
722        correctly by pce_dfa_exec(). It would match only one character.
724    18. A valid (though odd) pattern that looked like a POSIX character
725        class but used an invalid character after [ (for example [[,abc,]]) caused
726        pcre_compile() to give the error "Failed: internal error: code overflow" or
727        in some cases to crash with a glibc free() error. This could even happen if
728        the pattern terminated after [[ but there just happened to be a sequence of
729        letters, a binary zero, and a closing ] in the memory that followed.
731    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
732        over the years. Originally (before any Unicode support), just the bottom 8
733        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
734        output from "man perlunicode" includes this:
736          The regular expression compiler produces polymorphic opcodes.  That
737          is, the pattern adapts to the data and automatically switches to
738          the Unicode character scheme when presented with Unicode data--or
739          instead uses a traditional byte scheme when presented with byte
740          data.
742        Sadly, a wide octal escape does not cause a switch, and in a string with
743        no other multibyte characters, these octal escapes are treated as before.
744        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
745        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
746        Unicode string.
748        I have not perpetrated such confusion in PCRE. Up till now, it took just
749        the bottom 8 bits, as in old Perl. I have now made octal escapes with
750        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
751        translate to the appropriate multibyte character.
753    29. Applied some refactoring to reduce the number of warnings from Microsoft
754        and Borland compilers. This has included removing the fudge introduced
755        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
756        a warning about an unused variable.
758    21. PCRE has not included VT (character 0x0b) in the set of whitespace
759        characters since release 4.0, because Perl (from release 5.004) does not.
760        [Or at least, is documented not to: some releases seem to be in conflict
761        with the documentation.] However, when a pattern was studied with
762        pcre_study() and all its branches started with \s, PCRE still included VT
763        as a possible starting character. Of course, this did no harm; it just
764        caused an unnecessary match attempt.
766    22. Removed a now-redundant internal flag bit that recorded the fact that case
767        dependency changed within the pattern. This was once needed for "required
768        byte" processing, but is no longer used. This recovers a now-scarce options
769        bit. Also moved the least significant internal flag bit to the most-
770        significant bit of the word, which was not previously used (hangover from
771        the days when it was an int rather than a uint) to free up another bit for
772        the future.
774    23. Added support for CRLF line endings as well as CR and LF. As well as the
775        default being selectable at build time, it can now be changed at runtime
776        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
777        specify that it is scanning data with non-default line endings.
779    24. Changed the definition of CXXLINK to make it agree with the definition of
780        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
782    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
783        recursions. This makes a big different to stack usage for some patterns.
785    26. If a subpattern containing a named recursion or subroutine reference such
786        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
787        the space required for the compiled pattern went wrong and gave too small a
788        value. Depending on the environment, this could lead to "Failed: internal
789        error: code overflow at offset 49" or "glibc detected double free or
790        corruption" errors.
792    27. Applied patches from Google (a) to support the new newline modes and (b) to
793        advance over multibyte UTF-8 characters in GlobalReplace.
795    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
796        difference for some implementation of PCRE in some Windows version.
798    29. Added some extra testing facilities to pcretest:
800        \q<number>   in a data line sets the "match limit" value
801        \Q<number>   in a data line sets the "match recursion limt" value
802        -S <number>  sets the stack size, where <number> is in megabytes
804        The -S option isn't available for Windows.
807    Version 6.6 06-Feb-06
808    ---------------------
810     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
811        in pcreposix.h. I have copied the definition from pcre.h.
813     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
814        because pcre.h is no longer a built file.
816     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
817        not normally included in the compiled code.
820    Version 6.5 01-Feb-06
821    ---------------------
823     1. When using the partial match feature with pcre_dfa_exec(), it was not
824        anchoring the second and subsequent partial matches at the new starting
825        point. This could lead to incorrect results. For example, with the pattern
826        /1234/, partially matching against "123" and then "a4" gave a match.
828     2. Changes to pcregrep:
830        (a) All non-match returns from pcre_exec() were being treated as failures
831            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
832            error message is output. Some extra information is given for the
833            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
834            probably the only errors that are likely to be caused by users (by
835            specifying a regex that has nested indefinite repeats, for instance).
836            If there are more than 20 of these errors, pcregrep is abandoned.
838        (b) A binary zero was treated as data while matching, but terminated the
839            output line if it was written out. This has been fixed: binary zeroes
840            are now no different to any other data bytes.
842        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
843            used to set a locale for matching. The --locale=xxxx long option has
844            been added (no short equivalent) to specify a locale explicitly on the
845            pcregrep command, overriding the environment variables.
847        (d) When -B was used with -n, some line numbers in the output were one less
848            than they should have been.
850        (e) Added the -o (--only-matching) option.
852        (f) If -A or -C was used with -c (count only), some lines of context were
853            accidentally printed for the final match.
855        (g) Added the -H (--with-filename) option.
857        (h) The combination of options -rh failed to suppress file names for files
858            that were found from directory arguments.
860        (i) Added the -D (--devices) and -d (--directories) options.
862        (j) Added the -F (--fixed-strings) option.
864        (k) Allow "-" to be used as a file name for -f as well as for a data file.
866        (l) Added the --colo(u)r option.
868        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
869            is not present by default.
871     3. A nasty bug was discovered in the handling of recursive patterns, that is,
872        items such as (?R) or (?1), when the recursion could match a number of
873        alternatives. If it matched one of the alternatives, but subsequently,
874        outside the recursion, there was a failure, the code tried to back up into
875        the recursion. However, because of the way PCRE is implemented, this is not
876        possible, and the result was an incorrect result from the match.
878        In order to prevent this happening, the specification of recursion has
879        been changed so that all such subpatterns are automatically treated as
880        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
882     4. I had overlooked the fact that, in some locales, there are characters for
883        which isalpha() is true but neither isupper() nor islower() are true. In
884        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
885        and ordfeminine) are like this. This affected the treatment of \w and \W
886        when they appeared in character classes, but not when they appeared outside
887        a character class. The bit map for "word" characters is now created
888        separately from the results of isalnum() instead of just taking it from the
889        upper, lower, and digit maps. (Plus the underscore character, of course.)
891     5. The above bug also affected the handling of POSIX character classes such as
892        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
893        permanent tables. Instead, the bit maps for such a class were previously
894        created as the appropriate unions of the upper, lower, and digit bitmaps.
895        Now they are created by subtraction from the [[:word:]] class, which has
896        its own bitmap.
898     6. The [[:blank:]] character class matches horizontal, but not vertical space.
899        It is created by subtracting the vertical space characters (\x09, \x0a,
900        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
901        subtraction was done in the overall bitmap for a character class, meaning
902        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
903        be recognized. This bug has been fixed.
905     7. Patches from the folks at Google:
907          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
908          real life, but is still worth protecting against".
910          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
911          regular expressions".
913          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
914          have it.
916          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
917          "configure" and the latter not, in order to fix a problem somebody had
918          with compiling the Arg class on HP-UX.
920          (e) Improve the error-handling of the C++ wrapper a little bit.
922          (f) New tests for checking recursion limiting.
924     8. The pcre_memmove() function, which is used only if the environment does not
925        have a standard memmove() function (and is therefore rarely compiled),
926        contained two bugs: (a) use of int instead of size_t, and (b) it was not
927        returning a result (though PCRE never actually uses the result).
929     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
930        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
931        returned instead of calling malloc() with an overflowing number that would
932        most likely cause subsequent chaos.
934    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
936    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
937        with this option is matched, the nmatch and pmatch options of regexec() are
938        ignored.
940    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
941        provided in case anyone wants to the the POSIX interface with UTF-8
942        strings.
944    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
945        C++ linking (needed for some HP-UX environments).
947    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
948        (unused parameter) and in the pcre_printint() function (omitted "default"
949        switch label when the default is to do nothing).
951    15. Added some code to make it possible, when PCRE is compiled as a C++
952        library, to replace subject pointers for pcre_exec() with a smart pointer
953        class, thus making it possible to process discontinuous strings.
955    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
956        much the same function. They were added by different people who were trying
957        to make PCRE easy to compile on non-Unix systems. It has been suggested
958        that PCRE_EXPORT be abolished now that there is more automatic apparatus
959        for compiling on Windows systems. I have therefore replaced it with
960        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
961        defaults to "extern" for C or "extern C" for C++, which works fine on
962        Unix-like systems. It is now possible to override the value of PCRE_DATA_
963        SCOPE with something explicit in config.h. In addition:
965        (a) pcreposix.h still had just "extern" instead of either of these macros;
966            I have replaced it with PCRE_DATA_SCOPE.
968        (b) Functions such as _pcre_xclass(), which are internal to the library,
969            but external in the C sense, all had PCRE_EXPORT in their definitions.
970            This is apparently wrong for the Windows case, so I have removed it.
971            (It makes no difference on Unix-like systems.)
973    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
974        of recursive calls to match(). This is different to MATCH_LIMIT because
975        that limits the total number of calls to match(), not all of which increase
976        the depth of recursion. Limiting the recursion depth limits the amount of
977        stack (or heap if NO_RECURSE is set) that is used. The default can be set
978        when PCRE is compiled, and changed at run time. A patch from Google adds
979        this functionality to the C++ interface.
981    18. Changes to the handling of Unicode character properties:
983        (a) Updated the table to Unicode 4.1.0.
985        (b) Recognize characters that are not in the table as "Cn" (undefined).
987        (c) I revised the way the table is implemented to a much improved format
988            which includes recognition of ranges. It now supports the ranges that
989            are defined in UnicodeData.txt, and it also amalgamates other
990            characters into ranges. This has reduced the number of entries in the
991            table from around 16,000 to around 3,000, thus reducing its size
992            considerably. I realized I did not need to use a tree structure after
993            all - a binary chop search is just as efficient. Having reduced the
994            number of entries, I extended their size from 6 bytes to 8 bytes to
995            allow for more data.
997        (d) Added support for Unicode script names via properties such as \p{Han}.
999    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1000        matching that character.
1002    20. When matching a repeated Unicode property with a minimum greater than zero,
1003        (for example \pL{2,}), PCRE could look past the end of the subject if it
1004        reached it while seeking the minimum number of characters. This could
1005        happen only if some of the characters were more than one byte long, because
1006        there is a check for at least the minimum number of bytes.
1008    21. Refactored the implementation of \p and \P so as to be more general, to
1009        allow for more different types of property in future. This has changed the
1010        compiled form incompatibly. Anybody with saved compiled patterns that use
1011        \p or \P will have to recompile them.
1013    22. Added "Any" and "L&" to the supported property types.
1015    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1016        but give a compile time error if the value is greater than 0xff.
1018    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1019        accidentally not being installed or uninstalled.
1021    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1022        made were to insert the current release number. This seemed silly, because
1023        it made things harder for people building PCRE on systems that don't run
1024        "configure". I have turned pcre.h into a distributed file, no longer built
1025        by "configure", with the version identification directly included. There is
1026        no longer a pcre.h.in file.
1028        However, this change necessitated a change to the pcre-config script as
1029        well. It is built from pcre-config.in, and one of the substitutions was the
1030        release number. I have updated configure.ac so that ./configure now finds
1031        the release number by grepping pcre.h.
1033    26. Added the ability to run the tests under valgrind.
1036    Version 6.4 05-Sep-05
1037    ---------------------
1039     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1040        "--" to be printed when multiple files were scanned, even when none of the
1041        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1042        consider it to be a bug, and have restored the previous behaviour.
1044     2. A couple of code tidies to get rid of compiler warnings.
1046     3. The pcretest program used to cheat by referring to symbols in the library
1047        whose names begin with _pcre_. These are internal symbols that are not
1048        really supposed to be visible externally, and in some environments it is
1049        possible to suppress them. The cheating is now confined to including
1050        certain files from the library's source, which is a bit cleaner.
1052     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1053        file's purpose clearer.
1055     5. Reorganized pcre_ucp_findchar().
1058  Version 6.3 15-Aug-05  Version 6.3 15-Aug-05
1059  ---------------------  ---------------------

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