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revision 61 by nigel, Sat Feb 24 21:39:58 2007 UTC revision 219 by ph10, Thu Aug 16 11:46:40 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4  Version 3.0 02-Jan-02  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.
141    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
142        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
145    Version 7.2 19-Jun-07
146    ---------------------
148     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
149        which is apparently normally available under Windows.
151     2. Re-jig the pcregrep tests with different newline settings in an attempt
152        to make them independent of the local environment's newline setting.
154     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
156     4. Some of the "internals" tests were previously cut out when the link size
157        was not 2, because the output contained actual offsets. The recent new
158        "Z" feature of pcretest means that these can be cut out, making the tests
159        usable with all link sizes.
161     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
162        stack recursion. This gives a massive performance boost under BSD, but just
163        a small improvement under Linux. However, it saves one field in the frame
164        in all cases.
166     6. Added more features from the forthcoming Perl 5.10:
168        (a) (?-n) (where n is a string of digits) is a relative subroutine or
169            recursion call. It refers to the nth most recently opened parentheses.
171        (b) (?+n) is also a relative subroutine call; it refers to the nth next
172            to be opened parentheses.
174        (c) Conditions that refer to capturing parentheses can be specified
175            relatively, for example, (?(-2)... or (?(+3)...
177        (d) \K resets the start of the current match so that everything before
178            is not part of it.
180        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
182        (f) \g{name} is another synonym - part of Perl 5.10's unification of
183            reference syntax.
185        (g) (?| introduces a group in which the numbering of parentheses in each
186            alternative starts with the same number.
188        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
190     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
193     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
194        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
195        for detecting groups that can match an empty string.
197     9. A pattern with a very large number of alternatives (more than several
198        hundred) was running out of internal workspace during the pre-compile
199        phase, where pcre_compile() figures out how much memory will be needed. A
200        bit of new cunning has reduced the workspace needed for groups with
201        alternatives. The 1000-alternative test pattern now uses 12 bytes of
202        workspace instead of running out of the 4096 that are available.
204    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
206    11. Applied patch from Google to remove an optimization that didn't quite work.
207        The report of the bug said:
209          pcrecpp::RE("a*").FullMatch("aaa") matches, while
210          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
211          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
213    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
214        it matched the wrong number of bytes.
217    Version 7.1 24-Apr-07
218    ---------------------
220     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
221        that is more "standard", making use of automake and other Autotools. There
222        is some re-arrangement of the files and adjustment of comments consequent
223        on this.
225     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
226        for recursive directory scanning broke on some systems because the files
227        are not scanned in any specific order and on different systems the order
228        was different. A call to "sort" has been inserted into RunGrepTest for the
229        approprate test as a short-term fix. In the longer term there may be an
230        alternative.
232     3. I had an email from Eric Raymond about problems translating some of PCRE's
233        man pages to HTML (despite the fact that I distribute HTML pages, some
234        people do their own conversions for various reasons). The problems
235        concerned the use of low-level troff macros .br and .in. I have therefore
236        removed all such uses from the man pages (some were redundant, some could
237        be replaced by .nf/.fi pairs). The 132html script that I use to generate
238        HTML has been updated to handle .nf/.fi and to complain if it encounters
239        .br or .in.
241     4. Updated comments in configure.ac that get placed in config.h.in and also
242        arranged for config.h to be included in the distribution, with the name
243        config.h.generic, for the benefit of those who have to compile without
244        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
246     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
247        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
248        makevp.bat for the current PCRE, using the additional files
249        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
251     6. A Windows user reported a minor discrepancy with test 2, which turned out
252        to be caused by a trailing space on an input line that had got lost in his
253        copy. The trailing space was an accident, so I've just removed it.
255     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
256        that is needed.
258     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
259        as "const" (a) because they are and (b) because it helps the PHP
260        maintainers who have recently made a script to detect big data structures
261        in the php code that should be moved to the .rodata section. I remembered
262        to update Builducptable as well, so it won't revert if ucptable.h is ever
263        re-created.
265     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
266        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
267        order to be able to cut out the UTF-8 tables in the latter when UTF-8
268        support is not required. This saves 1.5-2K of code, which is important in
269        some applications.
271        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
272        so as not to refer to the tables, even though these functions will never be
273        called when UTF-8 support is disabled. Otherwise there are problems with a
274        shared library.
276    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
278        (a) It was defining its arguments as char * instead of void *.
280        (b) It was assuming that all moves were upwards in memory; this was true
281            a long time ago when I wrote it, but is no longer the case.
283        The emulated memove() is provided for those environments that have neither
284        memmove() nor bcopy(). I didn't think anyone used it these days, but that
285        is clearly not the case, as these two bugs were recently reported.
287    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
288        and Detrail to create the HTML documentation, the .txt form of the man
289        pages, and it removes trailing spaces from listed files. It also creates
290        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
291        case, it wraps all the #defines with #ifndefs. This script should be run
292        before "make dist".
294    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
295        with Unicode property support.
297        (a) For a maximizing quantifier, if the two different cases of the
298            character were of different lengths in their UTF-8 codings (there are
299            some cases like this - I found 11), and the matching function had to
300            back up over a mixture of the two cases, it incorrectly assumed they
301            were both the same length.
303        (b) When PCRE was configured to use the heap rather than the stack for
304            recursion during matching, it was not correctly preserving the data for
305            the other case of a UTF-8 character when checking ahead for a match
306            while processing a minimizing repeat. If the check also involved
307            matching a wide character, but failed, corruption could cause an
308            erroneous result when trying to check for a repeat of the original
309            character.
311    13. Some tidying changes to the testing mechanism:
313        (a) The RunTest script now detects the internal link size and whether there
314            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
315            values substituted by "configure". (The RunGrepTest script already did
316            this for UTF-8.) The configure.ac script no longer substitutes the
317            relevant variables.
319        (b) The debugging options /B and /D in pcretest show the compiled bytecode
320            with length and offset values. This means that the output is different
321            for different internal link sizes. Test 2 is skipped for link sizes
322            other than 2 because of this, bypassing the problem. Unfortunately,
323            there was also a test in test 3 (the locale tests) that used /B and
324            failed for link sizes other than 2. Rather than cut the whole test out,
325            I have added a new /Z option to pcretest that replaces the length and
326            offset values with spaces. This is now used to make test 3 independent
327            of link size. (Test 2 will be tidied up later.)
329    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
330        segmentation fault instead of returning the appropriate error message.
332    15. In multiline mode when the newline sequence was set to "any", the pattern
333        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
334        This doesn't seem right; it now treats the CRLF combination as the line
335        ending, and so does not match in that case. It's only a pattern such as ^$
336        that would hit this one: something like ^ABC$ would have failed after \r
337        and then tried again after \r\n.
339    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
340        in an attempt to make files that differ only in their line terminators
341        compare equal. This works on Linux.
343    17. Under certain error circumstances pcregrep might try to free random memory
344        as it exited. This is now fixed, thanks to valgrind.
346    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
347        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
348        was because its rules for how to advance for /g after matching an empty
349        string at the end of a line did not allow for this case. They now check for
350        it specially.
352    20. pcretest is supposed to handle patterns and data of any length, by
353        extending its buffers when necessary. It was getting this wrong when the
354        buffer for a data line had to be extended.
356    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
357        CRLF as a newline sequence.
359    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
360        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
361        I have nevertheless tidied it up.
363    23. Added some casts to kill warnings from HP-UX ia64 compiler.
365    24. Added a man page for pcre-config.
368    Version 7.0 19-Dec-06
369    ---------------------
371     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
372        moving to gcc 4.1.1.
374     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
375        sys/time.h, which is documented as needed for this function. It doesn't
376        seem to matter on Linux, but it showed up on some releases of OS X.
378     3. It seems that there are systems where bytes whose values are greater than
379        127 match isprint() in the "C" locale. The "C" locale should be the
380        default when a C program starts up. In most systems, only ASCII printing
381        characters match isprint(). This difference caused the output from pcretest
382        to vary, making some of the tests fail. I have changed pcretest so that:
384        (a) When it is outputting text in the compiled version of a pattern, bytes
385            other than 32-126 are always shown as hex escapes.
387        (b) When it is outputting text that is a matched part of a subject string,
388            it does the same, unless a different locale has been set for the match
389            (using the /L modifier). In this case, it uses isprint() to decide.
391     4. Fixed a major bug that caused incorrect computation of the amount of memory
392        required for a compiled pattern when options that changed within the
393        pattern affected the logic of the preliminary scan that determines the
394        length. The relevant options are -x, and -i in UTF-8 mode. The result was
395        that the computed length was too small. The symptoms of this bug were
396        either the PCRE error "internal error: code overflow" from pcre_compile(),
397        or a glibc crash with a message such as "pcretest: free(): invalid next
398        size (fast)". Examples of patterns that provoked this bug (shown in
399        pcretest format) are:
401          /(?-x: )/x
402          /(?x)(?-x: \s*#\s*)/
403          /((?i)[\x{c0}])/8
404          /(?i:[\x{c0}])/8
406        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
407        is now done differently.
409     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
410        wrapper classes; (b) implement a new function in the C++ scanner that is
411        more efficient than the old way of doing things because it avoids levels of
412        recursion in the regex matching; (c) add a paragraph to the documentation
413        for the FullMatch() function.
415     6. The escape sequence \n was being treated as whatever was defined as
416        "newline". Not only was this contrary to the documentation, which states
417        that \n is character 10 (hex 0A), but it also went horribly wrong when
418        "newline" was defined as CRLF. This has been fixed.
420     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
421        was being set to -1 for the "end of line" case (supposedly a value that no
422        character can have). Though this value is never used (the check for end of
423        line is "zero bytes in current character"), it caused compiler complaints.
424        I've changed it to 0xffffffff.
426     8. In pcre_version.c, the version string was being built by a sequence of
427        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
428        string (as it is for production releases) called a macro with an empty
429        argument. The C standard says the result of this is undefined. The gcc
430        compiler treats it as an empty string (which was what was wanted) but it is
431        reported that Visual C gives an error. The source has been hacked around to
432        avoid this problem.
434     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
435        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
436        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
437        of them did).
439    10. Originally, pcretest opened its input and output without "b"; then I was
440        told that "b" was needed in some environments, so it was added for release
441        5.0 to both the input and output. (It makes no difference on Unix-like
442        systems.) Later I was told that it is wrong for the input on Windows. I've
443        now abstracted the modes into two macros, to make it easier to fiddle with
444        them, and removed "b" from the input mode under Windows.
446    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
448    12. Added -help and --help to pcretest as an official way of being reminded
449        of the options.
451    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
452        and pcrecpp.cc because they annoy compilers at high warning levels.
454    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
456    15. Fixed an occurrence of == in configure.ac that should have been = (shell
457        scripts are not C programs :-) and which was not noticed because it works
458        on Linux.
460    16. pcretest is supposed to handle any length of pattern and data line (as one
461        line or as a continued sequence of lines) by extending its input buffer if
462        necessary. This feature was broken for very long pattern lines, leading to
463        a string of junk being passed to pcre_compile() if the pattern was longer
464        than about 50K.
466    17. I have done a major re-factoring of the way pcre_compile() computes the
467        amount of memory needed for a compiled pattern. Previously, there was code
468        that made a preliminary scan of the pattern in order to do this. That was
469        OK when PCRE was new, but as the facilities have expanded, it has become
470        harder and harder to keep it in step with the real compile phase, and there
471        have been a number of bugs (see for example, 4 above). I have now found a
472        cunning way of running the real compile function in a "fake" mode that
473        enables it to compute how much memory it would need, while actually only
474        ever using a few hundred bytes of working memory and without too many
475        tests of the mode. This should make future maintenance and development
476        easier. A side effect of this work is that the limit of 200 on the nesting
477        depth of parentheses has been removed (though this was never a serious
478        limitation, I suspect). However, there is a downside: pcre_compile() now
479        runs more slowly than before (30% or more, depending on the pattern). I
480        hope this isn't a big issue. There is no effect on runtime performance.
482    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
483        newline (only possible for the last line of a file) and it was a
484        pattern that set a locale (followed by /Lsomething), pcretest crashed.
486    19. Added additional timing features to pcretest. (1) The -tm option now times
487        matching only, not compiling. (2) Both -t and -tm can be followed, as a
488        separate command line item, by a number that specifies the number of
489        repeats to use when timing. The default is 50000; this gives better
490        precision, but takes uncomfortably long for very large patterns.
492    20. Extended pcre_study() to be more clever in cases where a branch of a
493        subpattern has no definite first character. For example, (a*|b*)[cd] would
494        previously give no result from pcre_study(). Now it recognizes that the
495        first character must be a, b, c, or d.
497    21. There was an incorrect error "recursive call could loop indefinitely" if
498        a subpattern (or the entire pattern) that was being tested for matching an
499        empty string contained only one non-empty item after a nested subpattern.
500        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
501        incorrectly, because the \d was being skipped in the check.
503    22. The pcretest program now has a new pattern option /B and a command line
504        option -b, which is equivalent to adding /B to every pattern. This causes
505        it to show the compiled bytecode, without the additional information that
506        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
507        is the same as /B/I).
509    23. A new optimization is now able automatically to treat some sequences such
510        as a*b as a*+b. More specifically, if something simple (such as a character
511        or a simple class like \d) has an unlimited quantifier, and is followed by
512        something that cannot possibly match the quantified thing, the quantifier
513        is automatically "possessified".
515    24. A recursive reference to a subpattern whose number was greater than 39
516        went wrong under certain circumstances in UTF-8 mode. This bug could also
517        have affected the operation of pcre_study().
519    25. Realized that a little bit of performance could be had by replacing
520        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
522    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
524    27. Possessive quantifiers such as a++ were previously implemented by turning
525        them into atomic groups such as ($>a+). Now they have their own opcodes,
526        which improves performance. This includes the automatically created ones
527        from 23 above.
529    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
530        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
531        the first matched character to be a colon. This applied both to named and
532        numbered groups.
534    29. The ucpinternal.h header file was missing its idempotency #ifdef.
536    30. I was sent a "project" file called libpcre.a.dev which I understand makes
537        building PCRE on Windows easier, so I have included it in the distribution.
539    31. There is now a check in pcretest against a ridiculously large number being
540        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
541        loop, the loop is abandoned.
543    32. Forward references to subpatterns in conditions such as (?(2)...) where
544        subpattern 2 is defined later cause pcre_compile() to search forwards in
545        the pattern for the relevant set of parentheses. This search went wrong
546        when there were unescaped parentheses in a character class, parentheses
547        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
549    33. "Subroutine" calls and backreferences were previously restricted to
550        referencing subpatterns earlier in the regex. This restriction has now
551        been removed.
553    34. Added a number of extra features that are going to be in Perl 5.10. On the
554        whole, these are just syntactic alternatives for features that PCRE had
555        previously implemented using the Python syntax or my own invention. The
556        other formats are all retained for compatibility.
558        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
559            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
560            also .NET compatible.
562        (b) A recursion or subroutine call to a named group can now be defined as
563            (?&name) as well as (?P>name).
565        (c) A backreference to a named group can now be defined as \k<name> or
566            \k'name' as well as (?P=name). The new forms, as well as being in Perl
567            5.10, are also .NET compatible.
569        (d) A conditional reference to a named group can now use the syntax
570            (?(<name>) or (?('name') as well as (?(name).
572        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
573            groups (named and numbered) that are never evaluated inline, but can be
574            called as "subroutines" from elsewhere. In effect, the DEFINE condition
575            is always false. There may be only one alternative in such a group.
577        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
578            as the simple (?(R). The condition is true only if the most recent
579            recursion is that of the given number or name. It does not search out
580            through the entire recursion stack.
582        (g) The escape \gN or \g{N} has been added, where N is a positive or
583            negative number, specifying an absolute or relative reference.
585    35. Tidied to get rid of some further signed/unsigned compiler warnings and
586        some "unreachable code" warnings.
588    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
589        things, this adds five new scripts.
591    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
592        There were also incompatibilities regarding the handling of \Q..\E inside
593        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
594        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
596    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
597        matches an empty string, and forcibly breaks the loop. There were bugs in
598        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
599        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
600        separate and independent bugs (that affected different cases) have been
601        fixed.
603    39. Refactored the code to abolish the use of different opcodes for small
604        capturing bracket numbers. This is a tidy that I avoided doing when I
605        removed the limit on the number of capturing brackets for 3.5 back in 2001.
606        The new approach is not only tidier, it makes it possible to reduce the
607        memory needed to fix the previous bug (38).
609    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
610        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
611        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
612        mode.
614    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
615        report.
617    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
618        copy construction and assignment in the C++ wrapper.
620    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
621        couple of bugs that could have given wrong results in the "--newline=crlf"
622        case.
624    44. Added a number of casts and did some reorganization of signed/unsigned int
625        variables following suggestions from Dair Grant. Also renamed the variable
626        "this" as "item" because it is a C++ keyword.
628    45. Arranged for dftables to add
630          #include "pcre_internal.h"
632        to pcre_chartables.c because without it, gcc 4.x may remove the array
633        definition from the final binary if PCRE is built into a static library and
634        dead code stripping is activated.
636    46. For an unanchored pattern, if a match attempt fails at the start of a
637        newline sequence, and the newline setting is CRLF or ANY, and the next two
638        characters are CRLF, advance by two characters instead of one.
641    Version 6.7 04-Jul-06
642    ---------------------
644     1. In order to handle tests when input lines are enormously long, pcretest has
645        been re-factored so that it automatically extends its buffers when
646        necessary. The code is crude, but this _is_ just a test program. The
647        default size has been increased from 32K to 50K.
649     2. The code in pcre_study() was using the value of the re argument before
650        testing it for NULL. (Of course, in any sensible call of the function, it
651        won't be NULL.)
653     3. The memmove() emulation function in pcre_internal.h, which is used on
654        systems that lack both memmove() and bcopy() - that is, hardly ever -
655        was missing a "static" storage class specifier.
657     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
658        containing an extended class (one that cannot be represented by a bitmap
659        because it contains high-valued characters or Unicode property items, e.g.
660        [\pZ]). Almost always one would set UTF-8 mode when processing such a
661        pattern, but PCRE should not loop if you do not (it no longer does).
662        [Detail: two cases were found: (a) a repeated subpattern containing an
663        extended class; (b) a recursive reference to a subpattern that followed a
664        previous extended class. It wasn't skipping over the extended class
665        correctly when UTF-8 mode was not set.]
667     5. A negated single-character class was not being recognized as fixed-length
668        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
669        compile error "lookbehind assertion is not fixed length".
671     6. The RunPerlTest auxiliary script was showing an unexpected difference
672        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
673        write a Perl script that can interpret lines of an input file either as
674        byte characters or as UTF-8, which is what "perltest" was being required to
675        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
676        can't do is switch easily at run time between having the "use utf8;" pragma
677        or not. In the end, I fudged it by using the RunPerlTest script to insert
678        "use utf8;" explicitly for the UTF-8 tests.
680     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
681        the end of the subject string, contrary to the documentation and to what
682        Perl does. This was true of both matching functions. Now it matches only at
683        the start of the subject and immediately after *internal* newlines.
685     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
686        a pointer to an int instead of a pointer to an unsigned long int. This
687        caused problems on 64-bit systems.
689     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
690        instance of the 'standard' template library not being so standard".
692    10. There was no check on the number of named subpatterns nor the maximum
693        length of a subpattern name. The product of these values is used to compute
694        the size of the memory block for a compiled pattern. By supplying a very
695        long subpattern name and a large number of named subpatterns, the size
696        computation could be caused to overflow. This is now prevented by limiting
697        the length of names to 32 characters, and the number of named subpatterns
698        to 10,000.
700    11. Subpatterns that are repeated with specific counts have to be replicated in
701        the compiled pattern. The size of memory for this was computed from the
702        length of the subpattern and the repeat count. The latter is limited to
703        65535, but there was no limit on the former, meaning that integer overflow
704        could in principle occur. The compiled length of a repeated subpattern is
705        now limited to 30,000 bytes in order to prevent this.
707    12. Added the optional facility to have named substrings with the same name.
709    13. Added the ability to use a named substring as a condition, using the
710        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
711        are numbers (not recommended). Forward references are permitted.
713    14. Added forward references in named backreferences (if you see what I mean).
715    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
716        pattern could run off the end of the subject. For example, the pattern
717        "(?s)(.{1,5})"8 did this with the subject "ab".
719    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
720        PCRE_CASELESS was set when matching characters that were quantified with ?
721        or *.
723    17. A character class other than a single negated character that had a minimum
724        but no maximum quantifier - for example [ab]{6,} - was not handled
725        correctly by pce_dfa_exec(). It would match only one character.
727    18. A valid (though odd) pattern that looked like a POSIX character
728        class but used an invalid character after [ (for example [[,abc,]]) caused
729        pcre_compile() to give the error "Failed: internal error: code overflow" or
730        in some cases to crash with a glibc free() error. This could even happen if
731        the pattern terminated after [[ but there just happened to be a sequence of
732        letters, a binary zero, and a closing ] in the memory that followed.
734    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
735        over the years. Originally (before any Unicode support), just the bottom 8
736        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
737        output from "man perlunicode" includes this:
739          The regular expression compiler produces polymorphic opcodes.  That
740          is, the pattern adapts to the data and automatically switches to
741          the Unicode character scheme when presented with Unicode data--or
742          instead uses a traditional byte scheme when presented with byte
743          data.
745        Sadly, a wide octal escape does not cause a switch, and in a string with
746        no other multibyte characters, these octal escapes are treated as before.
747        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
748        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
749        Unicode string.
751        I have not perpetrated such confusion in PCRE. Up till now, it took just
752        the bottom 8 bits, as in old Perl. I have now made octal escapes with
753        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
754        translate to the appropriate multibyte character.
756    29. Applied some refactoring to reduce the number of warnings from Microsoft
757        and Borland compilers. This has included removing the fudge introduced
758        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
759        a warning about an unused variable.
761    21. PCRE has not included VT (character 0x0b) in the set of whitespace
762        characters since release 4.0, because Perl (from release 5.004) does not.
763        [Or at least, is documented not to: some releases seem to be in conflict
764        with the documentation.] However, when a pattern was studied with
765        pcre_study() and all its branches started with \s, PCRE still included VT
766        as a possible starting character. Of course, this did no harm; it just
767        caused an unnecessary match attempt.
769    22. Removed a now-redundant internal flag bit that recorded the fact that case
770        dependency changed within the pattern. This was once needed for "required
771        byte" processing, but is no longer used. This recovers a now-scarce options
772        bit. Also moved the least significant internal flag bit to the most-
773        significant bit of the word, which was not previously used (hangover from
774        the days when it was an int rather than a uint) to free up another bit for
775        the future.
777    23. Added support for CRLF line endings as well as CR and LF. As well as the
778        default being selectable at build time, it can now be changed at runtime
779        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
780        specify that it is scanning data with non-default line endings.
782    24. Changed the definition of CXXLINK to make it agree with the definition of
783        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
785    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
786        recursions. This makes a big different to stack usage for some patterns.
788    26. If a subpattern containing a named recursion or subroutine reference such
789        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
790        the space required for the compiled pattern went wrong and gave too small a
791        value. Depending on the environment, this could lead to "Failed: internal
792        error: code overflow at offset 49" or "glibc detected double free or
793        corruption" errors.
795    27. Applied patches from Google (a) to support the new newline modes and (b) to
796        advance over multibyte UTF-8 characters in GlobalReplace.
798    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
799        difference for some implementation of PCRE in some Windows version.
801    29. Added some extra testing facilities to pcretest:
803        \q<number>   in a data line sets the "match limit" value
804        \Q<number>   in a data line sets the "match recursion limt" value
805        -S <number>  sets the stack size, where <number> is in megabytes
807        The -S option isn't available for Windows.
810    Version 6.6 06-Feb-06
811    ---------------------
813     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
814        in pcreposix.h. I have copied the definition from pcre.h.
816     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
817        because pcre.h is no longer a built file.
819     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
820        not normally included in the compiled code.
823    Version 6.5 01-Feb-06
824    ---------------------
826     1. When using the partial match feature with pcre_dfa_exec(), it was not
827        anchoring the second and subsequent partial matches at the new starting
828        point. This could lead to incorrect results. For example, with the pattern
829        /1234/, partially matching against "123" and then "a4" gave a match.
831     2. Changes to pcregrep:
833        (a) All non-match returns from pcre_exec() were being treated as failures
834            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
835            error message is output. Some extra information is given for the
836            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
837            probably the only errors that are likely to be caused by users (by
838            specifying a regex that has nested indefinite repeats, for instance).
839            If there are more than 20 of these errors, pcregrep is abandoned.
841        (b) A binary zero was treated as data while matching, but terminated the
842            output line if it was written out. This has been fixed: binary zeroes
843            are now no different to any other data bytes.
845        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
846            used to set a locale for matching. The --locale=xxxx long option has
847            been added (no short equivalent) to specify a locale explicitly on the
848            pcregrep command, overriding the environment variables.
850        (d) When -B was used with -n, some line numbers in the output were one less
851            than they should have been.
853        (e) Added the -o (--only-matching) option.
855        (f) If -A or -C was used with -c (count only), some lines of context were
856            accidentally printed for the final match.
858        (g) Added the -H (--with-filename) option.
860        (h) The combination of options -rh failed to suppress file names for files
861            that were found from directory arguments.
863        (i) Added the -D (--devices) and -d (--directories) options.
865        (j) Added the -F (--fixed-strings) option.
867        (k) Allow "-" to be used as a file name for -f as well as for a data file.
869        (l) Added the --colo(u)r option.
871        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
872            is not present by default.
874     3. A nasty bug was discovered in the handling of recursive patterns, that is,
875        items such as (?R) or (?1), when the recursion could match a number of
876        alternatives. If it matched one of the alternatives, but subsequently,
877        outside the recursion, there was a failure, the code tried to back up into
878        the recursion. However, because of the way PCRE is implemented, this is not
879        possible, and the result was an incorrect result from the match.
881        In order to prevent this happening, the specification of recursion has
882        been changed so that all such subpatterns are automatically treated as
883        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
885     4. I had overlooked the fact that, in some locales, there are characters for
886        which isalpha() is true but neither isupper() nor islower() are true. In
887        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
888        and ordfeminine) are like this. This affected the treatment of \w and \W
889        when they appeared in character classes, but not when they appeared outside
890        a character class. The bit map for "word" characters is now created
891        separately from the results of isalnum() instead of just taking it from the
892        upper, lower, and digit maps. (Plus the underscore character, of course.)
894     5. The above bug also affected the handling of POSIX character classes such as
895        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
896        permanent tables. Instead, the bit maps for such a class were previously
897        created as the appropriate unions of the upper, lower, and digit bitmaps.
898        Now they are created by subtraction from the [[:word:]] class, which has
899        its own bitmap.
901     6. The [[:blank:]] character class matches horizontal, but not vertical space.
902        It is created by subtracting the vertical space characters (\x09, \x0a,
903        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
904        subtraction was done in the overall bitmap for a character class, meaning
905        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
906        be recognized. This bug has been fixed.
908     7. Patches from the folks at Google:
910          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
911          real life, but is still worth protecting against".
913          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
914          regular expressions".
916          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
917          have it.
919          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
920          "configure" and the latter not, in order to fix a problem somebody had
921          with compiling the Arg class on HP-UX.
923          (e) Improve the error-handling of the C++ wrapper a little bit.
925          (f) New tests for checking recursion limiting.
927     8. The pcre_memmove() function, which is used only if the environment does not
928        have a standard memmove() function (and is therefore rarely compiled),
929        contained two bugs: (a) use of int instead of size_t, and (b) it was not
930        returning a result (though PCRE never actually uses the result).
932     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
933        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
934        returned instead of calling malloc() with an overflowing number that would
935        most likely cause subsequent chaos.
937    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
939    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
940        with this option is matched, the nmatch and pmatch options of regexec() are
941        ignored.
943    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
944        provided in case anyone wants to the the POSIX interface with UTF-8
945        strings.
947    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
948        C++ linking (needed for some HP-UX environments).
950    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
951        (unused parameter) and in the pcre_printint() function (omitted "default"
952        switch label when the default is to do nothing).
954    15. Added some code to make it possible, when PCRE is compiled as a C++
955        library, to replace subject pointers for pcre_exec() with a smart pointer
956        class, thus making it possible to process discontinuous strings.
958    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
959        much the same function. They were added by different people who were trying
960        to make PCRE easy to compile on non-Unix systems. It has been suggested
961        that PCRE_EXPORT be abolished now that there is more automatic apparatus
962        for compiling on Windows systems. I have therefore replaced it with
963        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
964        defaults to "extern" for C or "extern C" for C++, which works fine on
965        Unix-like systems. It is now possible to override the value of PCRE_DATA_
966        SCOPE with something explicit in config.h. In addition:
968        (a) pcreposix.h still had just "extern" instead of either of these macros;
969            I have replaced it with PCRE_DATA_SCOPE.
971        (b) Functions such as _pcre_xclass(), which are internal to the library,
972            but external in the C sense, all had PCRE_EXPORT in their definitions.
973            This is apparently wrong for the Windows case, so I have removed it.
974            (It makes no difference on Unix-like systems.)
976    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
977        of recursive calls to match(). This is different to MATCH_LIMIT because
978        that limits the total number of calls to match(), not all of which increase
979        the depth of recursion. Limiting the recursion depth limits the amount of
980        stack (or heap if NO_RECURSE is set) that is used. The default can be set
981        when PCRE is compiled, and changed at run time. A patch from Google adds
982        this functionality to the C++ interface.
984    18. Changes to the handling of Unicode character properties:
986        (a) Updated the table to Unicode 4.1.0.
988        (b) Recognize characters that are not in the table as "Cn" (undefined).
990        (c) I revised the way the table is implemented to a much improved format
991            which includes recognition of ranges. It now supports the ranges that
992            are defined in UnicodeData.txt, and it also amalgamates other
993            characters into ranges. This has reduced the number of entries in the
994            table from around 16,000 to around 3,000, thus reducing its size
995            considerably. I realized I did not need to use a tree structure after
996            all - a binary chop search is just as efficient. Having reduced the
997            number of entries, I extended their size from 6 bytes to 8 bytes to
998            allow for more data.
1000        (d) Added support for Unicode script names via properties such as \p{Han}.
1002    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1003        matching that character.
1005    20. When matching a repeated Unicode property with a minimum greater than zero,
1006        (for example \pL{2,}), PCRE could look past the end of the subject if it
1007        reached it while seeking the minimum number of characters. This could
1008        happen only if some of the characters were more than one byte long, because
1009        there is a check for at least the minimum number of bytes.
1011    21. Refactored the implementation of \p and \P so as to be more general, to
1012        allow for more different types of property in future. This has changed the
1013        compiled form incompatibly. Anybody with saved compiled patterns that use
1014        \p or \P will have to recompile them.
1016    22. Added "Any" and "L&" to the supported property types.
1018    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1019        but give a compile time error if the value is greater than 0xff.
1021    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1022        accidentally not being installed or uninstalled.
1024    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1025        made were to insert the current release number. This seemed silly, because
1026        it made things harder for people building PCRE on systems that don't run
1027        "configure". I have turned pcre.h into a distributed file, no longer built
1028        by "configure", with the version identification directly included. There is
1029        no longer a pcre.h.in file.
1031        However, this change necessitated a change to the pcre-config script as
1032        well. It is built from pcre-config.in, and one of the substitutions was the
1033        release number. I have updated configure.ac so that ./configure now finds
1034        the release number by grepping pcre.h.
1036    26. Added the ability to run the tests under valgrind.
1039    Version 6.4 05-Sep-05
1040    ---------------------
1042     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1043        "--" to be printed when multiple files were scanned, even when none of the
1044        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1045        consider it to be a bug, and have restored the previous behaviour.
1047     2. A couple of code tidies to get rid of compiler warnings.
1049     3. The pcretest program used to cheat by referring to symbols in the library
1050        whose names begin with _pcre_. These are internal symbols that are not
1051        really supposed to be visible externally, and in some environments it is
1052        possible to suppress them. The cheating is now confined to including
1053        certain files from the library's source, which is a bit cleaner.
1055     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1056        file's purpose clearer.
1058     5. Reorganized pcre_ucp_findchar().
1061    Version 6.3 15-Aug-05
1062    ---------------------
1064     1. The file libpcre.pc.in did not have general read permission in the tarball.
1066     2. There were some problems when building without C++ support:
1068        (a) If C++ support was not built, "make install" and "make test" still
1069            tried to test it.
1071        (b) There were problems when the value of CXX was explicitly set. Some
1072            changes have been made to try to fix these, and ...
1074        (c) --disable-cpp can now be used to explicitly disable C++ support.
1076        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1077            backslash in a target when C++ was disabled. This confuses some
1078            versions of "make", apparently. Using an intermediate variable solves
1079            this. (Same for CPP_LOBJ.)
1081     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1082        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1083        necessary on certain architectures.
1085     4. Added a setting of -export-symbols-regex to the link command to remove
1086        those symbols that are exported in the C sense, but actually are local
1087        within the library, and not documented. Their names all begin with
1088        "_pcre_". This is not a perfect job, because (a) we have to except some
1089        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1090        available (and never for static libraries). I have made a note to try to
1091        find a way round (a) in the future.
1094    Version 6.2 01-Aug-05
1095    ---------------------
1097     1. There was no test for integer overflow of quantifier values. A construction
1098        such as {1111111111111111} would give undefined results. What is worse, if
1099        a minimum quantifier for a parenthesized subpattern overflowed and became
1100        negative, the calculation of the memory size went wrong. This could have
1101        led to memory overwriting.
1103     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1105     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1106        operating environments where this matters.
1108     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1109        PCRE options from within the C++ wrapper.
1111     5. Named capturing subpatterns were not being correctly counted when a pattern
1112        was compiled. This caused two problems: (a) If there were more than 100
1113        such subpatterns, the calculation of the memory needed for the whole
1114        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1115        back references of the form \12, where the number was greater than 9, were
1116        not recognized as back references, even though there were sufficient
1117        previous subpatterns.
1119     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1120        versions of gcc, e.g. 2.95.4.
1123    Version 6.1 21-Jun-05
1124    ---------------------
1126     1. There was one reference to the variable "posix" in pcretest.c that was not
1127        surrounded by "#if !defined NOPOSIX".
1129     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1130        the cross-check on the old pcre_info() function, for the benefit of the
1131        cut-down version of PCRE that is currently imported into Exim.
1133     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1134        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1135        patterns that start (?i) but I don't think that matters. The use of (?i) is
1136        just an example; this all applies to the other options as well.
1138     4. Since libtool seems to echo the compile commands it is issuing, the output
1139        from "make" can be reduced a bit by putting "@" in front of each libtool
1140        compile command.
1142     5. Patch from the folks at Google for configure.in to be a bit more thorough
1143        in checking for a suitable C++ installation before trying to compile the
1144        C++ stuff. This should fix a reported problem when a compiler was present,
1145        but no suitable headers.
1147     6. The man pages all had just "PCRE" as their title. I have changed them to
1148        be the relevant file name. I have also arranged that these names are
1149        retained in the file doc/pcre.txt, which is a concatenation in text format
1150        of all the man pages except the little individual ones for each function.
1152     7. The NON-UNIX-USE file had not been updated for the different set of source
1153        files that come with release 6. I also added a few comments about the C++
1154        wrapper.
1157    Version 6.0 07-Jun-05
1158    ---------------------
1160     1. Some minor internal re-organization to help with my DFA experiments.
1162     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1163        didn't matter for the library itself when fully configured, but did matter
1164        when compiling without UCP support, or within Exim, where the ucp files are
1165        not imported.
1167     3. Refactoring of the library code to split up the various functions into
1168        different source modules. The addition of the new DFA matching code (see
1169        below) to a single monolithic source would have made it really too
1170        unwieldy, quite apart from causing all the code to be include in a
1171        statically linked application, when only some functions are used. This is
1172        relevant even without the DFA addition now that patterns can be compiled in
1173        one application and matched in another.
1175        The downside of splitting up is that there have to be some external
1176        functions and data tables that are used internally in different modules of
1177        the library but which are not part of the API. These have all had their
1178        names changed to start with "_pcre_" so that they are unlikely to clash
1179        with other external names.
1181     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1182        a different (DFA) algorithm. Although it is slower than the original
1183        function, it does have some advantages for certain types of matching
1184        problem.
1186     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1187        including restarting after a partial match.
1189     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1190        defined when compiling for Windows was sent to me. I have put it into the
1191        code, though I have no means of testing or verifying it.
1193     7. Added the pcre_refcount() auxiliary function.
1195     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1196        match before or at the first newline in the subject string. In pcretest,
1197        the /f option on a pattern can be used to set this.
1199     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1200        would behave wrongly. This has been present in PCRE since release 4.0.
1202    10. A number of changes to the pcregrep command:
1204        (a) Refactored how -x works; insert ^(...)$ instead of setting
1205            PCRE_ANCHORED and checking the length, in preparation for adding
1206            something similar for -w.
1208        (b) Added the -w (match as a word) option.
1210        (c) Refactored the way lines are read and buffered so as to have more
1211            than one at a time available.
1213        (d) Implemented a pcregrep test script.
1215        (e) Added the -M (multiline match) option. This allows patterns to match
1216            over several lines of the subject. The buffering ensures that at least
1217            8K, or the rest of the document (whichever is the shorter) is available
1218            for matching (and similarly the previous 8K for lookbehind assertions).
1220        (f) Changed the --help output so that it now says
1222              -w, --word-regex(p)
1224            instead of two lines, one with "regex" and the other with "regexp"
1225            because that confused at least one person since the short forms are the
1226            same. (This required a bit of code, as the output is generated
1227            automatically from a table. It wasn't just a text change.)
1229        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1230            option but starts with a hyphen. Could be a pattern or a path name
1231            starting with a hyphen, for instance.
1233        (h) "-" can be given as a file name to represent stdin.
1235        (i) When file names are being printed, "(standard input)" is used for
1236            the standard input, for compatibility with GNU grep. Previously
1237            "<stdin>" was used.
1239        (j) The option --label=xxx can be used to supply a name to be used for
1240            stdin when file names are being printed. There is no short form.
1242        (k) Re-factored the options decoding logic because we are going to add
1243            two more options that take data. Such options can now be given in four
1244            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1246        (l) Added the -A, -B, and -C options for requesting that lines of context
1247            around matches be printed.
1249        (m) Added the -L option to print the names of files that do not contain
1250            any matching lines, that is, the complement of -l.
1252        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1253            continue to scan other files.
1255        (o) The -s option was incorrectly implemented. For compatibility with other
1256            greps, it now suppresses the error message for a non-existent or non-
1257            accessible file (but not the return code). There is a new option called
1258            -q that suppresses the output of matching lines, which was what -s was
1259            previously doing.
1261        (p) Added --include and --exclude options to specify files for inclusion
1262            and exclusion when recursing.
1264    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1265        Hopefully, it now does.
1267    12. Missing cast in pcre_study().
1269    13. Added an "uninstall" target to the makefile.
1271    14. Replaced "extern" in the function prototypes in Makefile.in with
1272        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1273        world, but is set differently for Windows.
1275    15. Added a second compiling function called pcre_compile2(). The only
1276        difference is that it has an extra argument, which is a pointer to an
1277        integer error code. When there is a compile-time failure, this is set
1278        non-zero, in addition to the error test pointer being set to point to an
1279        error message. The new argument may be NULL if no error number is required
1280        (but then you may as well call pcre_compile(), which is now just a
1281        wrapper). This facility is provided because some applications need a
1282        numeric error indication, but it has also enabled me to tidy up the way
1283        compile-time errors are handled in the POSIX wrapper.
1285    16. Added VPATH=.libs to the makefile; this should help when building with one
1286        prefix path and installing with another. (Or so I'm told by someone who
1287        knows more about this stuff than I do.)
1289    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1290        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1291        match everything, including newlines. This is not POSIX-compatible, but
1292        somebody wanted the feature. From pcretest it can be activated by using
1293        both the P and the s flags.
1295    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1297    19. libpcre.pc was being incorrectly installed as executable.
1299    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1300        it now also looks for '\r' so that it will work unmodified on Windows.
1302    21. Added Google's contributed C++ wrapper to the distribution.
1304    22. Added some untidy missing memory free() calls in pcretest, to keep
1305        Electric Fence happy when testing.
1309    Version 5.0 13-Sep-04
1310    ---------------------
1312     1. Internal change: literal characters are no longer packed up into items
1313        containing multiple characters in a single byte-string. Each character
1314        is now matched using a separate opcode. However, there may be more than one
1315        byte in the character in UTF-8 mode.
1317     2. The pcre_callout_block structure has two new fields: pattern_position and
1318        next_item_length. These contain the offset in the pattern to the next match
1319        item, and its length, respectively.
1321     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1322        insertion of callouts before each pattern item. Added the /C option to
1323        pcretest to make use of this.
1325     4. On the advice of a Windows user, the lines
1327          #if defined(_WIN32) || defined(WIN32)
1328          _setmode( _fileno( stdout ), 0x8000 );
1329          #endif  /* defined(_WIN32) || defined(WIN32) */
1331        have been added to the source of pcretest. This apparently does useful
1332        magic in relation to line terminators.
1334     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1335        for the benefit of those environments where the "b" makes a difference.
1337     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1338        to know about it. I have put a hack into configure.in that adds in code
1339        to set GCC=yes if CC=icc. This seems to end up at a point in the
1340        generated configure script that is early enough to affect the setting of
1341        compiler options, which is what is needed, but I have no means of testing
1342        whether it really works. (The user who reported this had patched the
1343        generated configure script, which of course I cannot do.)
1345        LATER: After change 22 below (new libtool files), the configure script
1346        seems to know about icc (and also ecc). Therefore, I have commented out
1347        this hack in configure.in.
1349     7. Added support for pkg-config (2 patches were sent in).
1351     8. Negated POSIX character classes that used a combination of internal tables
1352        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1353        [[:^ascii]]. Typically, they would match almost any characters. The other
1354        POSIX classes were not broken in this way.
1356     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1357        to find the match, as PCRE was deluded into thinking that the match had to
1358        start at the start point or following a newline. The same bug applied to
1359        patterns with negative forward assertions or any backward assertions
1360        preceding ".*" at the start, unless the pattern required a fixed first
1361        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1363    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1364        starting at the last subject character, bytes beyond the end of the subject
1365        string were read.
1367    11. Renamed the variable "class" as "classbits" to make life easier for C++
1368        users. (Previously there was a macro definition, but it apparently wasn't
1369        enough.)
1371    12. Added the new field "tables" to the extra data so that tables can be passed
1372        in at exec time, or the internal tables can be re-selected. This allows
1373        a compiled regex to be saved and re-used at a later time by a different
1374        program that might have everything at different addresses.
1376    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1377        -R library as well as a -L library.
1379    14. The debugging options of pcretest (-d on the command line or D on a
1380        pattern) showed incorrect output for anything following an extended class
1381        that contained multibyte characters and which was followed by a quantifier.
1383    15. Added optional support for general category Unicode character properties
1384        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1385        support. It adds about 90K to the size of the library. The meanings of the
1386        inbuilt class escapes such as \d and \s have NOT been changed.
1388    16. Updated pcredemo.c to include calls to free() to release the memory for the
1389        compiled pattern.
1391    17. The generated file chartables.c was being created in the source directory
1392        instead of in the building directory. This caused the build to fail if the
1393        source directory was different from the building directory, and was
1394        read-only.
1396    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1397        file. No doubt somebody will tell me if they don't make sense... Also added
1398        Dan Mooney's comments about building on OpenVMS.
1400    19. Added support for partial matching via the PCRE_PARTIAL option for
1401        pcre_exec() and the \P data escape in pcretest.
1403    20. Extended pcretest with 3 new pattern features:
1405        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1406              write the compiled pattern to the file whose name is "rest-of-line".
1407              This is a straight binary dump of the data, with the saved pointer to
1408              the character tables forced to be NULL. The study data, if any, is
1409              written too. After writing, pcretest reads a new pattern.
1411        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1412              compiled pattern from the given file. There must not be any
1413              occurrences of "<" in the file name (pretty unlikely); if there are,
1414              pcretest will instead treat the initial "<" as a pattern delimiter.
1415              After reading in the pattern, pcretest goes on to read data lines as
1416              usual.
1418        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1419              and 16-bit fields in a compiled pattern, to simulate a pattern that
1420              was compiled on a host of opposite endianness.
1422    21. The pcre-exec() function can now cope with patterns that were compiled on
1423        hosts of opposite endianness, with this restriction:
1425          As for any compiled expression that is saved and used later, the tables
1426          pointer field cannot be preserved; the extra_data field in the arguments
1427          to pcre_exec() should be used to pass in a tables address if a value
1428          other than the default internal tables were used at compile time.
1430    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1431        now diagnosed as an error. Previously, most of the time, a negative number
1432        would have been treated as zero, but if in addition "ovector" was passed as
1433        NULL, a crash could occur.
1435    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1436        new versions from the libtool 1.5 distribution (the last one is a copy of
1437        a file called libtool.m4). This seems to have fixed the need to patch
1438        "configure" to support Darwin 1.3 (which I used to do). However, I still
1439        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1440        workstation).
1442    24. Changed the PCRE licence to be the more standard "BSD" licence.
1445    Version 4.5 01-Dec-03
1446    ---------------------
1448     1. There has been some re-arrangement of the code for the match() function so
1449        that it can be compiled in a version that does not call itself recursively.
1450        Instead, it keeps those local variables that need separate instances for
1451        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1452        needs to "recurse". Keeping track of where control must go is done by means
1453        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1454        hide most of the details from the main code, and operates only if
1455        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1456        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1457        operating.
1459        To make it easier for callers to provide specially tailored get/free
1460        functions for this usage, two new functions, pcre_stack_malloc, and
1461        pcre_stack_free, are used. They are always called in strict stacking order,
1462        and the size of block requested is always the same.
1464        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1465        PCRE has been compiled to use the stack or the heap for recursion. The
1466        -C option of pcretest uses this to show which version is compiled.
1468        A new data escape \S, is added to pcretest; it causes the amounts of store
1469        obtained and freed by both kinds of malloc/free at match time to be added
1470        to the output.
1472     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1473        what's available on my current Linux desktop machine.
1475     3. When matching a UTF-8 string, the test for a valid string at the start has
1476        been extended. If start_offset is not zero, PCRE now checks that it points
1477        to a byte that is the start of a UTF-8 character. If not, it returns
1478        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1479        this is necessary because there may be backward assertions in the pattern.
1480        When matching the same subject several times, it may save resources to use
1481        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1483     4. The code for checking the validity of UTF-8 strings has been tightened so
1484        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1485        containing "overlong sequences".
1487     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1488        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1489        should have been "&", but it just so happened that all the cases this let
1490        through by mistake were picked up later in the function.
1492     6. I had used a variable called "isblank" - this is a C99 function, causing
1493        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1495     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1496        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1497        so the version is shown; (c) stop "make test" echoing "./RunTest".
1499     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1501     9. The prototype for memmove() for systems that don't have it was using
1502        size_t, but the inclusion of the header that defines size_t was later. I've
1503        moved the #includes for the C headers earlier to avoid this.
1505    10. Added some adjustments to the code to make it easier to compiler on certain
1506        special systems:
1508          (a) Some "const" qualifiers were missing.
1509          (b) Added the macro EXPORT before all exported functions; by default this
1510              is defined to be empty.
1511          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1512              that it reads its output file name as an argument instead of writing
1513              to the standard output and assuming this can be redirected.
1515    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1516        class containing characters with values greater than 255, PCRE compilation
1517        went into a loop.
1519    12. A recursive reference to a subpattern that was within another subpattern
1520        that had a minimum quantifier of zero caused PCRE to crash. For example,
1521        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1522        recursion. If the recursively-called subpattern itself had a zero repeat,
1523        that was OK.
1525    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1526        buffer into which it was copied (for escape processing) was still set at
1527        1024, so long lines caused crashes.
1529    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1530        "internal error: code overflow...". This applied to any character class
1531        that was followed by a possessive quantifier.
1533    15. Modified the Makefile to add libpcre.la as a prerequisite for
1534        libpcreposix.la because I was told this is needed for a parallel build to
1535        work.
1537    16. If a pattern that contained .* following optional items at the start was
1538        studied, the wrong optimizing data was generated, leading to matching
1539        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1540        matching string must start with a or b or c. The correct conclusion for
1541        this pattern is that a match can start with any character.
1544    Version 4.4 13-Aug-03
1545    ---------------------
1547     1. In UTF-8 mode, a character class containing characters with values between
1548        127 and 255 was not handled correctly if the compiled pattern was studied.
1549        In fixing this, I have also improved the studying algorithm for such
1550        classes (slightly).
1552     2. Three internal functions had redundant arguments passed to them. Removal
1553        might give a very teeny performance improvement.
1555     3. Documentation bug: the value of the capture_top field in a callout is *one
1556        more than* the number of the hightest numbered captured substring.
1558     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1559        in incorrectly linking with a previously installed version. They now link
1560        explicitly with libpcre.la.
1562     5. configure.in no longer needs to recognize Cygwin specially.
1564     6. A problem in pcre.in for Windows platforms is fixed.
1566     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1567        pcretest, it used to include the size of the study block as part of its
1568        output. Unfortunately, the structure contains a field that has a different
1569        size on different hardware architectures. This meant that the tests that
1570        showed this size failed. As the block is currently always of a fixed size,
1571        this information isn't actually particularly useful in pcretest output, so
1572        I have just removed it.
1574     8. Three pre-processor statements accidentally did not start in column 1.
1575        Sadly, there are *still* compilers around that complain, even though
1576        standard C has not required this for well over a decade. Sigh.
1578     9. In pcretest, the code for checking callouts passed small integers in the
1579        callout_data field, which is a void * field. However, some picky compilers
1580        complained about the casts involved for this on 64-bit systems. Now
1581        pcretest passes the address of the small integer instead, which should get
1582        rid of the warnings.
1584    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1585        both compile and run time, and gives an error if an invalid UTF-8 sequence
1586        is found. There is a option for disabling this check in cases where the
1587        string is known to be correct and/or the maximum performance is wanted.
1589    11. In response to a bug report, I changed one line in Makefile.in from
1591            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1592        to
1593            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1595        to look similar to other lines, but I have no way of telling whether this
1596        is the right thing to do, as I do not use Windows. No doubt I'll get told
1597        if it's wrong...
1600    Version 4.3 21-May-03
1601    ---------------------
1603    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1604       Makefile.
1606    2. Some refactoring to improve the quality of the code:
1608       (i)   The utf8_table... variables are now declared "const".
1610       (ii)  The code for \cx, which used the "case flipping" table to upper case
1611             lower case letters, now just substracts 32. This is ASCII-specific,
1612             but the whole concept of \cx is ASCII-specific, so it seems
1613             reasonable.
1615       (iii) PCRE was using its character types table to recognize decimal and
1616             hexadecimal digits in the pattern. This is silly, because it handles
1617             only 0-9, a-f, and A-F, but the character types table is locale-
1618             specific, which means strange things might happen. A private
1619             table is now used for this - though it costs 256 bytes, a table is
1620             much faster than multiple explicit tests. Of course, the standard
1621             character types table is still used for matching digits in subject
1622             strings against \d.
1624       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1625             ending in _t are). So I've renamed it as ESC_tee.
1627    3. The first argument for regexec() in the POSIX wrapper should have been
1628       defined as "const".
1630    4. Changed pcretest to use malloc() for its buffers so that they can be
1631       Electric Fenced for debugging.
1633    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1634       to read one or more bytes before the start of the subject string. Often this
1635       had no effect on PCRE's behaviour, but in some circumstances it could
1636       provoke a segmentation fault.
1638    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1639       to try to read one or more bytes before the start of the subject string.
1641    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1642       UTF-8 support could misbehave in various ways if the subject string
1643       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1644       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1645       back over UTF-8 characters.)
1648    Version 4.2 14-Apr-03
1649    ---------------------
1651    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1653    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1654         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1655         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1656         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1657         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1658           and BUILD_EXEEXT
1659         Note: automatic setting of the BUILD variables is not yet working
1660         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1661           compile-time but not at link-time
1662         [LINK]: use for linking executables only
1663         make different versions for Windows and non-Windows
1664         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1665           libraries
1666         [LINK_FOR_BUILD]: new variable
1667         [OBJEXT]: use throughout
1668         [EXEEXT]: use throughout
1669         <winshared>: new target
1670         <wininstall>: new target
1671         <dftables.o>: use native compiler
1672         <dftables>: use native linker
1673         <install>: handle Windows platform correctly
1674         <clean>: ditto
1675         <check>: ditto
1676         copy DLL to top builddir before testing
1678       As part of these changes, -no-undefined was removed again. This was reported
1679       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1680       in any case.
1682    3. Some tidies to get rid of compiler warnings:
1684       . In the match_data structure, match_limit was an unsigned long int, whereas
1685         match_call_count was an int. I've made them both unsigned long ints.
1687       . In pcretest the fact that a const uschar * doesn't automatically cast to
1688         a void * provoked a warning.
1690       . Turning on some more compiler warnings threw up some "shadow" variables
1691         and a few more missing casts.
1693    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1694       option, a class that contained a single character with a value between 128
1695       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1697    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1698       option, a class that contained several characters, but with at least one
1699       whose value was between 128 and 255 caused PCRE to crash.
1702    Version 4.1 12-Mar-03
1703    ---------------------
1705    1. Compiling with gcc -pedantic found a couple of places where casts were
1706    needed, and a string in dftables.c that was longer than standard compilers are
1707    required to support.
1709    2. Compiling with Sun's compiler found a few more places where the code could
1710    be tidied up in order to avoid warnings.
1712    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1713    first of these names is deprecated in the latest Autoconf in favour of the name
1714    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1715    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1716    analogy I have changed it to CFLAGS_FOR_BUILD.
1718    4. Added -no-undefined to the linking command in the Makefile, because this is
1719    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1720    linking step for the pcreposix library.
1722    5. PCRE was failing to diagnose the case of two named groups with the same
1723    name.
1725    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1726    literal character that is needed in the subject for a match, and scans along to
1727    ensure that it is present before embarking on the full matching process. This
1728    saves time in cases of nested unlimited repeats that are never going to match.
1729    Problem: the scan can take a lot of time if the subject is very long (e.g.
1730    megabytes), thus penalizing straightforward matches. It is now done only if the
1731    amount of subject to be scanned is less than 1000 bytes.
1733    7. A lesser problem with the same optimization is that it was recording the
1734    first character of an anchored pattern as "needed", thus provoking a search
1735    right along the subject, even when the first match of the pattern was going to
1736    fail. The "needed" character is now not set for anchored patterns, unless it
1737    follows something in the pattern that is of non-fixed length. Thus, it still
1738    fulfils its original purpose of finding quick non-matches in cases of nested
1739    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1742    Version 4.0 17-Feb-03
1743    ---------------------
1745    1. If a comment in an extended regex that started immediately after a meta-item
1746    extended to the end of string, PCRE compiled incorrect data. This could lead to
1747    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1749    2. Moved to autoconf 2.53 and libtool 1.4.2.
1751    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1752    the special perltest8 script is no longer needed - all the tests can be run
1753    from a single perltest script.
1755    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1756    by \s. It has now been removed in PCRE. This means it isn't recognized as
1757    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1758    class [:space:] *does* include VT, thereby creating a mess.
1760    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1761    space and tab.
1763    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1764    its new features into the main test script, reducing the number of scripts.
1766    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1767    were backward compatible, and made the (?i) apply to the whole pattern, as if
1768    /i were given. Now it behaves more logically, and applies the option setting
1769    only to what follows. PCRE has been changed to follow suit. However, if it
1770    finds options settings right at the start of the pattern, it extracts them into
1771    the global options, as before. Thus, they show up in the info data.
1773    8. Added support for the \Q...\E escape sequence. Characters in between are
1774    treated as literals. This is slightly different from Perl in that $ and @ are
1775    also handled as literals inside the quotes. In Perl, they will cause variable
1776    interpolation. Note the following examples:
1778        Pattern            PCRE matches      Perl matches
1780        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
1781        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
1782        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
1784    For compatibility with Perl, \Q...\E sequences are recognized inside character
1785    classes as well as outside them.
1787    9. Re-organized 3 code statements in pcretest to avoid "overflow in
1788    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1789    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1790    signed/unsigned warnings.
1792    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1793    option for pcretest, so I've replaced it by a simple function that does just
1794    that job.
1796    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1797    "pcregrep -".
1799    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1800    Java package. This provides some syntactic sugar for simple cases of what my
1801    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1802    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1803    item, you can use this simplified notation. Note that only makes sense with
1804    greedy quantifiers. Consequently, the use of the possessive quantifier forces
1805    greediness, whatever the setting of the PCRE_UNGREEDY option.
1807    13. A change of greediness default within a pattern was not taking effect at
1808    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1809    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1810    was abstracted outside.
1812    14. PCRE now supports the \G assertion. It is true when the current matching
1813    position is at the start point of the match. This differs from \A when the
1814    starting offset is non-zero. Used with the /g option of pcretest (or similar
1815    code), it works in the same way as it does for Perl's /g option. If all
1816    alternatives of a regex begin with \G, the expression is anchored to the start
1817    match position, and the "anchored" flag is set in the compiled expression.
1819    15. Some bugs concerning the handling of certain option changes within patterns
1820    have been fixed. These applied to options other than (?ims). For example,
1821    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1822    been the other way round. Some of this was related to change 7 above.
1824    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1825    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1826    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1827    POSIX classes only within a class (e.g. /[[:alpha:]]/).
1829    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1830    mode. Unlike ".", it always matches newline, whatever the setting of
1831    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1832    assertions. Perl allows it, but it doesn't (in general) work because it can't
1833    calculate the length of the lookbehind. At least, that's the case for Perl
1834    5.8.0 - I've been told they are going to document that it doesn't work in
1835    future.
1837    18. Added an error diagnosis for escapes that PCRE does not support: these are
1838    \L, \l, \N, \P, \p, \U, \u, and \X.
1840    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1841    reading past the end of the pattern in cases such as /[abcd/.
1843    20. PCRE was getting more memory than necessary for patterns with classes that
1844    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1846    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1847    compiling PCRE for use with Virtual Pascal.
1849    22. Small fix to the Makefile to make it work properly if the build is done
1850    outside the source tree.
1852    23. Added a new extension: a condition to go with recursion. If a conditional
1853    subpattern starts with (?(R) the "true" branch is used if recursion has
1854    happened, whereas the "false" branch is used only at the top level.
1856    24. When there was a very long string of literal characters (over 255 bytes
1857    without UTF support, over 250 bytes with UTF support), the computation of how
1858    much memory was required could be incorrect, leading to segfaults or other
1859    strange effects.
1861    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1862    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1863    there was a subsequent back reference to those brackets. This meant that, for
1864    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1865    possible to check for precisely this case. All we can do is abandon the
1866    optimization if .* occurs inside capturing brackets when there are any back
1867    references whatsoever. (See below for a better fix that came later.)
1869    26. The handling of the optimization for finding the first character of a
1870    non-anchored pattern, and for finding a character that is required later in the
1871    match were failing in some cases. This didn't break the matching; it just
1872    failed to optimize when it could. The way this is done has been re-implemented.
1874    27. Fixed typo in error message for invalid (?R item (it said "(?p").
1876    28. Added a new feature that provides some of the functionality that Perl
1877    provides with (?{...}). The facility is termed a "callout". The way it is done
1878    in PCRE is for the caller to provide an optional function, by setting
1879    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1880    global variable. By default it is unset, which disables all calling out. To get
1881    the function called, the regex must include (?C) at appropriate points. This
1882    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1883    This provides a means of identifying different callout points. When PCRE
1884    reaches such a point in the regex, if pcre_callout has been set, the external
1885    function is called. It is provided with data in a structure called
1886    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1887    matching continues; if it returns a non-zero value, the match at the current
1888    point fails. However, backtracking will occur if possible. [This was changed
1889    later and other features added - see item 49 below.]
1891    29. pcretest is upgraded to test the callout functionality. It provides a
1892    callout function that displays information. By default, it shows the start of
1893    the match and the current position in the text. There are some new data escapes
1894    to vary what happens:
1896        \C+         in addition, show current contents of captured substrings
1897        \C-         do not supply a callout function
1898        \C!n        return 1 when callout number n is reached
1899        \C!n!m      return 1 when callout number n is reached for the mth time
1901    30. If pcregrep was called with the -l option and just a single file name, it
1902    output "<stdin>" if a match was found, instead of the file name.
1904    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1905    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1906    pcre_exec(). This saves a malloc/free per call. The default value of
1907    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1908    when configuring.
1910    32. The default maximum size of a compiled pattern is 64K. There have been a
1911    few cases of people hitting this limit. The code now uses macros to handle the
1912    storing of links as offsets within the compiled pattern. It defaults to 2-byte
1913    links, but this can be changed to 3 or 4 bytes by --with-link-size when
1914    configuring. Tests 2 and 5 work only with 2-byte links because they output
1915    debugging information about compiled patterns.
1917    33. Internal code re-arrangements:
1919    (a) Moved the debugging function for printing out a compiled regex into
1920        its own source file (printint.c) and used #include to pull it into
1921        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1922        separate copies.
1924    (b) Defined the list of op-code names for debugging as a macro in
1925        internal.h so that it is next to the definition of the opcodes.
1927    (c) Defined a table of op-code lengths for simpler skipping along compiled
1928        code. This is again a macro in internal.h so that it is next to the
1929        definition of the opcodes.
1931    34. Added support for recursive calls to individual subpatterns, along the
1932    lines of Robin Houston's patch (but implemented somewhat differently).
1934    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1935    allow it to read and process whole directories in Win32. This code was
1936    contributed by Lionel Fourquaux; it has not been tested by me.
1938    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1939    used to name a group. Names consist of alphanumerics and underscores, and must
1940    be unique. Back references use the syntax (?P=name) and recursive calls use
1941    (?P>name) which is a PCRE extension to the Python extension. Groups still have
1942    numbers. The function pcre_fullinfo() can be used after compilation to extract
1943    a name/number map. There are three relevant calls:
1945      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
1946      PCRE_INFO_NAMECOUNT            yields the number of entries
1947      PCRE_INFO_NAMETABLE            yields a pointer to the map.
1949    The map is a vector of fixed-size entries. The size of each entry depends on
1950    the length of the longest name used. The first two bytes of each entry are the
1951    group number, most significant byte first. There follows the corresponding
1952    name, zero terminated. The names are in alphabetical order.
1954    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1955    case instead of 255. Making it the same both with and without UTF-8 support
1956    means that the same test output works with both.
1958    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1959    calling malloc() with a zero argument.
1961    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1962    optimization. I've improved things by keeping a bitmap of backreferences with
1963    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1964    fact referenced, the optimization can be applied. It is unlikely that a
1965    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1966    the match to follow \n) will appear inside brackets with a number greater than
1967    31, but if it does, any back reference > 31 suppresses the optimization.
1969    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1970    of disabling numbered capturing parentheses. Any opening parenthesis that is
1971    not followed by ? behaves as if it were followed by ?: but named parentheses
1972    can still be used for capturing (and they will acquire numbers in the usual
1973    way).
1975    41. Redesigned the return codes from the match() function into yes/no/error so
1976    that errors can be passed back from deep inside the nested calls. A malloc
1977    failure while inside a recursive subpattern call now causes the
1978    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1980    42. It is now possible to set a limit on the number of times the match()
1981    function is called in a call to pcre_exec(). This facility makes it possible to
1982    limit the amount of recursion and backtracking, though not in a directly
1983    obvious way, because the match() function is used in a number of different
1984    circumstances. The count starts from zero for each position in the subject
1985    string (for non-anchored patterns). The default limit is, for compatibility, a
1986    large number, namely 10 000 000. You can change this in two ways:
1988    (a) When configuring PCRE before making, you can use --with-match-limit=n
1989        to set a default value for the compiled library.
1991    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1992        a different value is set. See 45 below.
1994    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1996    43. Added a new function pcre_config(int, void *) to enable run-time extraction
1997    of things that can be changed at compile time. The first argument specifies
1998    what is wanted and the second points to where the information is to be placed.
1999    The current list of available information is:
2001      PCRE_CONFIG_UTF8
2003    The output is an integer that is set to one if UTF-8 support is available;
2004    otherwise it is set to zero.
2008    The output is an integer that it set to the value of the code that is used for
2009    newline. It is either LF (10) or CR (13).
2013    The output is an integer that contains the number of bytes used for internal
2014    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
2018    The output is an integer that contains the threshold above which the POSIX
2019    interface uses malloc() for output vectors. See item 31 above.
2023    The output is an unsigned integer that contains the default limit of the number
2024    of match() calls in a pcre_exec() execution. See 42 above.
2026    44. pcretest has been upgraded by the addition of the -C option. This causes it
2027    to extract all the available output from the new pcre_config() function, and to
2028    output it. The program then exits immediately.
2030    45. A need has arisen to pass over additional data with calls to pcre_exec() in
2031    order to support additional features. One way would have been to define
2032    pcre_exec2() (for example) with extra arguments, but this would not have been
2033    extensible, and would also have required all calls to the original function to
2034    be mapped to the new one. Instead, I have chosen to extend the mechanism that
2035    is used for passing in "extra" data from pcre_study().
2037    The pcre_extra structure is now exposed and defined in pcre.h. It currently
2038    contains the following fields:
2040      flags         a bitmap indicating which of the following fields are set
2041      study_data    opaque data from pcre_study()
2042      match_limit   a way of specifying a limit on match() calls for a specific
2043                      call to pcre_exec()
2044      callout_data  data for callouts (see 49 below)
2046    The flag bits are also defined in pcre.h, and are
2052    The pcre_study() function now returns one of these new pcre_extra blocks, with
2053    the actual study data pointed to by the study_data field, and the
2054    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
2055    before. That is, this change is entirely upwards-compatible and requires no
2056    change to existing code.
2058    If you want to pass in additional data to pcre_exec(), you can either place it
2059    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2060    block.
2062    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2063    data string contains the escape sequence \M, pcretest calls pcre_exec() several
2064    times with different match limits, until it finds the minimum value needed for
2065    pcre_exec() to complete. The value is then output. This can be instructive; for
2066    most simple matches the number is quite small, but for pathological cases it
2067    gets very large very quickly.
2069    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2070    returns the size of the data block pointed to by the study_data field in a
2071    pcre_extra block, that is, the value that was passed as the argument to
2072    pcre_malloc() when PCRE was getting memory in which to place the information
2073    created by pcre_study(). The fourth argument should point to a size_t variable.
2074    pcretest has been extended so that this information is shown after a successful
2075    pcre_study() call when information about the compiled regex is being displayed.
2077    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2078    because what follows is always an absolute path. (Later: it turns out that this
2079    is more than cosmetic for MinGW, because it doesn't like empty path
2080    components.)
2082    49. Some changes have been made to the callout feature (see 28 above):
2084    (i)  A callout function now has three choices for what it returns:
2086           0  =>  success, carry on matching
2087         > 0  =>  failure at this point, but backtrack if possible
2088         < 0  =>  serious error, return this value from pcre_exec()
2090         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2091         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2092         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2093         use by callout functions. It will never be used by PCRE itself.
2095    (ii) The pcre_extra structure (see 45 above) has a void * field called
2096         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2097         pcre_callout_block structure has a field of the same name. The contents of
2098         the field passed in the pcre_extra structure are passed to the callout
2099         function in the corresponding field in the callout block. This makes it
2100         easier to use the same callout-containing regex from multiple threads. For
2101         testing, the pcretest program has a new data escape
2103           \C*n        pass the number n (may be negative) as callout_data
2105         If the callout function in pcretest receives a non-zero value as
2106         callout_data, it returns that value.
2108    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2109    there were some redundant $(CFLAGS) in commands that are now specified as
2110    $(LINK), which already includes $(CFLAGS).
2112    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2113    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2114    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2115    one-byte characters throughout. Note that case-insensitive matching applies
2116    only to characters whose values are less than 256. PCRE doesn't support the
2117    notion of cases for higher-valued characters.
2119    (i)   A character class whose characters are all within 0-255 is handled as
2120          a bit map, and the map is inverted for negative classes. Previously, a
2121          character > 255 always failed to match such a class; however it should
2122          match if the class was a negative one (e.g. [^ab]). This has been fixed.
2124    (ii)  A negated character class with a single character < 255 is coded as
2125          "not this character" (OP_NOT). This wasn't working properly when the test
2126          character was multibyte, either singly or repeated.
2128    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2129          mode, for example: \x{100}{2,3}.
2131    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2132          singly or repeated) now correctly test multibyte characters. However,
2133          PCRE doesn't recognize any characters with values greater than 255 as
2134          digits, spaces, or word characters. Such characters always match \D, \S,
2135          and \W, and never match \d, \s, or \w.
2137    (v)   Classes may now contain characters and character ranges with values
2138          greater than 255. For example: [ab\x{100}-\x{400}].
2140    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
2141          PCRE in UTF-8 mode.
2143    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2144    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2145    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2146    value.)
2148    53. The single man page has become too large. I have therefore split it up into
2149    a number of separate man pages. These also give rise to individual HTML pages;
2150    these are now put in a separate directory, and there is an index.html page that
2151    lists them all. Some hyperlinking between the pages has been installed.
2153    54. Added convenience functions for handling named capturing parentheses.
2155    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2156    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2157    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2158    are faulted.
2160    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2161    calling configure. These values are used when compiling the dftables.c program
2162    which is run to generate the source of the default character tables. They
2163    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2164    you will need to set these values.
2166    57. Updated the building process for Windows DLL, as provided by Fred Cox.
2169    Version 3.9 02-Jan-02
2170  ---------------------  ---------------------
2172  1. A bit of extraneous text had somehow crept into the pcregrep documentation.  1. A bit of extraneous text had somehow crept into the pcregrep documentation.

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