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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.1 05-Mar-07
5    ---------------------
7     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
8        that is more "standard", making use of automake and other autotools. There
9        is some re-arrangement of the files and adjustment of comments consequent
10        on this.
12     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
13        for recursive directory scanning broke on some systems because the files
14        are not scanned in any specific order and on different systems the order
15        was different. A call to "sort" has been inserted into RunGrepTest for the
16        approprate test as a short-term fix. In the longer term there may be an
17        alternative.
19     3. I had an email from Eric Raymond about problems translating some of PCRE's
20        man pages to HTML (despite the fact that I distribute HTML pages, some
21        people do their own conversions for various reasons). The problems
22        concerned the use of low-level troff macros .br and .in. I have therefore
23        removed all such uses from the man pages (some were redundant, some could
24        be replaced by .nf/.fi pairs). The 132html script that I use to generate
25        HTML has been updated to handle .nf/.fi and to complain if it encounters
26        .br or .in.
28     4. Updated comments in configure.ac that get placed in config.h.in and also
29        arranged for config.h to be included in the distribution, with the name
30        config.h.generic, for the benefit of those who have to compile without
31        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
33     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
34        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
35        makevp.bat for the current PCRE, using the additional files !compile.txt,
36        !linklib.txt, and pcregexp.pas.
38     6. A Windows user reported a minor discrepancy with test 2, which turned out
39        to be caused by a trailing space on an input line that had got lost in his
40        copy. The trailing space was an accident, so I've just removed it.
42     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
43        that is needed.
45     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
46        as "const" (a) because they are and (b) because it helps the PHP
47        maintainers who have recently made a script to detect big data structures
48        in the php code that should be moved to the .rodata section. I remembered
49        to update Builducptable as well, so it won't revert if ucptable.h is ever
50        re-created.
52     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
53        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
54        order to be able to cut out the UTF-8 tables in the latter when UTF-8
55        support is not required. This saves 1.5-2K of code, which is important in
56        some applications.
58        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
59        so as not to refer to the tables, even though these functions will never be
60        called when UTF-8 support is disabled. Otherwise there are problems with a
61        shared library.
63    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
65        (a) It was defining its arguments as char * instead of void *.
67        (b) It was assuming that all moves were upwards in memory; this was true
68            a long time ago when I wrote it, but is no longer the case.
70        The emulated memove() is provided for those environments that have neither
71        memmove() nor bcopy(). I didn't think anyone used it these days, but that
72        is clearly not the case, as these two bugs were recently reported.
74    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
75        and Detrail to create the HTML documentation, the .txt form of the man
76        pages, and it removes trailing spaces from listed files. It also creates
77        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
78        case, it wraps all the #defines with #ifndefs. This script should be run
79        before "make dist".
81    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
82        with Unicode property support.
84        (a) For a maximizing quantifier, if the two different cases of the
85            character were of different lengths in their UTF-8 codings (there are
86            some cases like this - I found 11), and the matching function had to
87            back up over a mixture of the two cases, it incorrectly assumed they
88            were both the same length.
90        (b) When PCRE was configured to use the heap rather than the stack for
91            recursion during matching, it was not correctly preserving the data for
92            the other case of a UTF-8 character when checking ahead for a match
93            while processing a minimizing repeat. If the check also involved
94            matching a wide character, but failed, corruption could cause an
95            erroneous result when trying to check for a repeat of the original
96            character.
98    13. Some tidying changes to the testing mechanism:
100        (a) The RunTest script now detects the internal link size and whether there
101            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
102            values substituted by "configure". (The RunGrepTest script already did
103            this for UTF-8.) The configure.ac script no longer substitutes the
104            relevant variables.
106        (b) The debugging options /B and /D in pcretest show the compiled bytecode
107            with length and offset values. This means that the output is different
108            for different internal link sizes. Test 2 is skipped for link sizes
109            other than 2 because of this, bypassing the problem. Unfortunately,
110            there was also a test in test 3 (the locale tests) that used /B and
111            failed for link sizes other than 2. Rather than cut the whole test out,
112            I have added a new /Z option to pcretest that replaces the length and
113            offset values with spaces. This is now used to make test 3 independent
114            of link size.
117    Version 7.0 19-Dec-06
118    ---------------------
120     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
121        moving to gcc 4.1.1.
123     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
124        sys/time.h, which is documented as needed for this function. It doesn't
125        seem to matter on Linux, but it showed up on some releases of OS X.
127     3. It seems that there are systems where bytes whose values are greater than
128        127 match isprint() in the "C" locale. The "C" locale should be the
129        default when a C program starts up. In most systems, only ASCII printing
130        characters match isprint(). This difference caused the output from pcretest
131        to vary, making some of the tests fail. I have changed pcretest so that:
133        (a) When it is outputting text in the compiled version of a pattern, bytes
134            other than 32-126 are always shown as hex escapes.
136        (b) When it is outputting text that is a matched part of a subject string,
137            it does the same, unless a different locale has been set for the match
138            (using the /L modifier). In this case, it uses isprint() to decide.
140     4. Fixed a major bug that caused incorrect computation of the amount of memory
141        required for a compiled pattern when options that changed within the
142        pattern affected the logic of the preliminary scan that determines the
143        length. The relevant options are -x, and -i in UTF-8 mode. The result was
144        that the computed length was too small. The symptoms of this bug were
145        either the PCRE error "internal error: code overflow" from pcre_compile(),
146        or a glibc crash with a message such as "pcretest: free(): invalid next
147        size (fast)". Examples of patterns that provoked this bug (shown in
148        pcretest format) are:
150          /(?-x: )/x
151          /(?x)(?-x: \s*#\s*)/
152          /((?i)[\x{c0}])/8
153          /(?i:[\x{c0}])/8
155        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
156        is now done differently.
158     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
159        wrapper classes; (b) implement a new function in the C++ scanner that is
160        more efficient than the old way of doing things because it avoids levels of
161        recursion in the regex matching; (c) add a paragraph to the documentation
162        for the FullMatch() function.
164     6. The escape sequence \n was being treated as whatever was defined as
165        "newline". Not only was this contrary to the documentation, which states
166        that \n is character 10 (hex 0A), but it also went horribly wrong when
167        "newline" was defined as CRLF. This has been fixed.
169     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
170        was being set to -1 for the "end of line" case (supposedly a value that no
171        character can have). Though this value is never used (the check for end of
172        line is "zero bytes in current character"), it caused compiler complaints.
173        I've changed it to 0xffffffff.
175     8. In pcre_version.c, the version string was being built by a sequence of
176        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
177        string (as it is for production releases) called a macro with an empty
178        argument. The C standard says the result of this is undefined. The gcc
179        compiler treats it as an empty string (which was what was wanted) but it is
180        reported that Visual C gives an error. The source has been hacked around to
181        avoid this problem.
183     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
184        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
185        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
186        of them did).
188    10. Originally, pcretest opened its input and output without "b"; then I was
189        told that "b" was needed in some environments, so it was added for release
190        5.0 to both the input and output. (It makes no difference on Unix-like
191        systems.) Later I was told that it is wrong for the input on Windows. I've
192        now abstracted the modes into two macros, to make it easier to fiddle with
193        them, and removed "b" from the input mode under Windows.
195    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
197    12. Added -help and --help to pcretest as an official way of being reminded
198        of the options.
200    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
201        and pcrecpp.cc because they annoy compilers at high warning levels.
203    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
205    15. Fixed an occurrence of == in configure.ac that should have been = (shell
206        scripts are not C programs :-) and which was not noticed because it works
207        on Linux.
209    16. pcretest is supposed to handle any length of pattern and data line (as one
210        line or as a continued sequence of lines) by extending its input buffer if
211        necessary. This feature was broken for very long pattern lines, leading to
212        a string of junk being passed to pcre_compile() if the pattern was longer
213        than about 50K.
215    17. I have done a major re-factoring of the way pcre_compile() computes the
216        amount of memory needed for a compiled pattern. Previously, there was code
217        that made a preliminary scan of the pattern in order to do this. That was
218        OK when PCRE was new, but as the facilities have expanded, it has become
219        harder and harder to keep it in step with the real compile phase, and there
220        have been a number of bugs (see for example, 4 above). I have now found a
221        cunning way of running the real compile function in a "fake" mode that
222        enables it to compute how much memory it would need, while actually only
223        ever using a few hundred bytes of working memory and without too many
224        tests of the mode. This should make future maintenance and development
225        easier. A side effect of this work is that the limit of 200 on the nesting
226        depth of parentheses has been removed (though this was never a serious
227        limitation, I suspect). However, there is a downside: pcre_compile() now
228        runs more slowly than before (30% or more, depending on the pattern). I
229        hope this isn't a big issue. There is no effect on runtime performance.
231    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
232        newline (only possible for the last line of a file) and it was a
233        pattern that set a locale (followed by /Lsomething), pcretest crashed.
235    19. Added additional timing features to pcretest. (1) The -tm option now times
236        matching only, not compiling. (2) Both -t and -tm can be followed, as a
237        separate command line item, by a number that specifies the number of
238        repeats to use when timing. The default is 50000; this gives better
239        precision, but takes uncomfortably long for very large patterns.
241    20. Extended pcre_study() to be more clever in cases where a branch of a
242        subpattern has no definite first character. For example, (a*|b*)[cd] would
243        previously give no result from pcre_study(). Now it recognizes that the
244        first character must be a, b, c, or d.
246    21. There was an incorrect error "recursive call could loop indefinitely" if
247        a subpattern (or the entire pattern) that was being tested for matching an
248        empty string contained only one non-empty item after a nested subpattern.
249        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
250        incorrectly, because the \d was being skipped in the check.
252    22. The pcretest program now has a new pattern option /B and a command line
253        option -b, which is equivalent to adding /B to every pattern. This causes
254        it to show the compiled bytecode, without the additional information that
255        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
256        is the same as /B/I).
258    23. A new optimization is now able automatically to treat some sequences such
259        as a*b as a*+b. More specifically, if something simple (such as a character
260        or a simple class like \d) has an unlimited quantifier, and is followed by
261        something that cannot possibly match the quantified thing, the quantifier
262        is automatically "possessified".
264    24. A recursive reference to a subpattern whose number was greater than 39
265        went wrong under certain circumstances in UTF-8 mode. This bug could also
266        have affected the operation of pcre_study().
268    25. Realized that a little bit of performance could be had by replacing
269        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
271    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
273    27. Possessive quantifiers such as a++ were previously implemented by turning
274        them into atomic groups such as ($>a+). Now they have their own opcodes,
275        which improves performance. This includes the automatically created ones
276        from 23 above.
278    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
279        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
280        the first matched character to be a colon. This applied both to named and
281        numbered groups.
283    29. The ucpinternal.h header file was missing its idempotency #ifdef.
285    30. I was sent a "project" file called libpcre.a.dev which I understand makes
286        building PCRE on Windows easier, so I have included it in the distribution.
288    31. There is now a check in pcretest against a ridiculously large number being
289        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
290        loop, the loop is abandoned.
292    32. Forward references to subpatterns in conditions such as (?(2)...) where
293        subpattern 2 is defined later cause pcre_compile() to search forwards in
294        the pattern for the relevant set of parentheses. This search went wrong
295        when there were unescaped parentheses in a character class, parentheses
296        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
298    33. "Subroutine" calls and backreferences were previously restricted to
299        referencing subpatterns earlier in the regex. This restriction has now
300        been removed.
302    34. Added a number of extra features that are going to be in Perl 5.10. On the
303        whole, these are just syntactic alternatives for features that PCRE had
304        previously implemented using the Python syntax or my own invention. The
305        other formats are all retained for compatibility.
307        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
308            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
309            also .NET compatible.
311        (b) A recursion or subroutine call to a named group can now be defined as
312            (?&name) as well as (?P>name).
314        (c) A backreference to a named group can now be defined as \k<name> or
315            \k'name' as well as (?P=name). The new forms, as well as being in Perl
316            5.10, are also .NET compatible.
318        (d) A conditional reference to a named group can now use the syntax
319            (?(<name>) or (?('name') as well as (?(name).
321        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
322            groups (named and numbered) that are never evaluated inline, but can be
323            called as "subroutines" from elsewhere. In effect, the DEFINE condition
324            is always false. There may be only one alternative in such a group.
326        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
327            as the simple (?(R). The condition is true only if the most recent
328            recursion is that of the given number or name. It does not search out
329            through the entire recursion stack.
331        (g) The escape \gN or \g{N} has been added, where N is a positive or
332            negative number, specifying an absolute or relative reference.
334    35. Tidied to get rid of some further signed/unsigned compiler warnings and
335        some "unreachable code" warnings.
337    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
338        things, this adds five new scripts.
340    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
341        There were also incompatibilities regarding the handling of \Q..\E inside
342        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
343        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
345    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
346        matches an empty string, and forcibly breaks the loop. There were bugs in
347        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
348        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
349        separate and independent bugs (that affected different cases) have been
350        fixed.
352    39. Refactored the code to abolish the use of different opcodes for small
353        capturing bracket numbers. This is a tidy that I avoided doing when I
354        removed the limit on the number of capturing brackets for 3.5 back in 2001.
355        The new approach is not only tidier, it makes it possible to reduce the
356        memory needed to fix the previous bug (38).
358    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
359        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
360        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
361        mode.
363    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
364        report.
366    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
367        copy construction and assignment in the C++ wrapper.
369    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
370        couple of bugs that could have given wrong results in the "--newline=crlf"
371        case.
373    44. Added a number of casts and did some reorganization of signed/unsigned int
374        variables following suggestions from Dair Grant. Also renamed the variable
375        "this" as "item" because it is a C++ keyword.
377    45. Arranged for dftables to add
379          #include "pcre_internal.h"
381        to pcre_chartables.c because without it, gcc 4.x may remove the array
382        definition from the final binary if PCRE is built into a static library and
383        dead code stripping is activated.
385    46. For an unanchored pattern, if a match attempt fails at the start of a
386        newline sequence, and the newline setting is CRLF or ANY, and the next two
387        characters are CRLF, advance by two characters instead of one.
390    Version 6.7 04-Jul-06
391    ---------------------
393     1. In order to handle tests when input lines are enormously long, pcretest has
394        been re-factored so that it automatically extends its buffers when
395        necessary. The code is crude, but this _is_ just a test program. The
396        default size has been increased from 32K to 50K.
398     2. The code in pcre_study() was using the value of the re argument before
399        testing it for NULL. (Of course, in any sensible call of the function, it
400        won't be NULL.)
402     3. The memmove() emulation function in pcre_internal.h, which is used on
403        systems that lack both memmove() and bcopy() - that is, hardly ever -
404        was missing a "static" storage class specifier.
406     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
407        containing an extended class (one that cannot be represented by a bitmap
408        because it contains high-valued characters or Unicode property items, e.g.
409        [\pZ]). Almost always one would set UTF-8 mode when processing such a
410        pattern, but PCRE should not loop if you do not (it no longer does).
411        [Detail: two cases were found: (a) a repeated subpattern containing an
412        extended class; (b) a recursive reference to a subpattern that followed a
413        previous extended class. It wasn't skipping over the extended class
414        correctly when UTF-8 mode was not set.]
416     5. A negated single-character class was not being recognized as fixed-length
417        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
418        compile error "lookbehind assertion is not fixed length".
420     6. The RunPerlTest auxiliary script was showing an unexpected difference
421        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
422        write a Perl script that can interpret lines of an input file either as
423        byte characters or as UTF-8, which is what "perltest" was being required to
424        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
425        can't do is switch easily at run time between having the "use utf8;" pragma
426        or not. In the end, I fudged it by using the RunPerlTest script to insert
427        "use utf8;" explicitly for the UTF-8 tests.
429     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
430        the end of the subject string, contrary to the documentation and to what
431        Perl does. This was true of both matching functions. Now it matches only at
432        the start of the subject and immediately after *internal* newlines.
434     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
435        a pointer to an int instead of a pointer to an unsigned long int. This
436        caused problems on 64-bit systems.
438     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
439        instance of the 'standard' template library not being so standard".
441    10. There was no check on the number of named subpatterns nor the maximum
442        length of a subpattern name. The product of these values is used to compute
443        the size of the memory block for a compiled pattern. By supplying a very
444        long subpattern name and a large number of named subpatterns, the size
445        computation could be caused to overflow. This is now prevented by limiting
446        the length of names to 32 characters, and the number of named subpatterns
447        to 10,000.
449    11. Subpatterns that are repeated with specific counts have to be replicated in
450        the compiled pattern. The size of memory for this was computed from the
451        length of the subpattern and the repeat count. The latter is limited to
452        65535, but there was no limit on the former, meaning that integer overflow
453        could in principle occur. The compiled length of a repeated subpattern is
454        now limited to 30,000 bytes in order to prevent this.
456    12. Added the optional facility to have named substrings with the same name.
458    13. Added the ability to use a named substring as a condition, using the
459        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
460        are numbers (not recommended). Forward references are permitted.
462    14. Added forward references in named backreferences (if you see what I mean).
464    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
465        pattern could run off the end of the subject. For example, the pattern
466        "(?s)(.{1,5})"8 did this with the subject "ab".
468    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
469        PCRE_CASELESS was set when matching characters that were quantified with ?
470        or *.
472    17. A character class other than a single negated character that had a minimum
473        but no maximum quantifier - for example [ab]{6,} - was not handled
474        correctly by pce_dfa_exec(). It would match only one character.
476    18. A valid (though odd) pattern that looked like a POSIX character
477        class but used an invalid character after [ (for example [[,abc,]]) caused
478        pcre_compile() to give the error "Failed: internal error: code overflow" or
479        in some cases to crash with a glibc free() error. This could even happen if
480        the pattern terminated after [[ but there just happened to be a sequence of
481        letters, a binary zero, and a closing ] in the memory that followed.
483    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
484        over the years. Originally (before any Unicode support), just the bottom 8
485        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
486        output from "man perlunicode" includes this:
488          The regular expression compiler produces polymorphic opcodes.  That
489          is, the pattern adapts to the data and automatically switches to
490          the Unicode character scheme when presented with Unicode data--or
491          instead uses a traditional byte scheme when presented with byte
492          data.
494        Sadly, a wide octal escape does not cause a switch, and in a string with
495        no other multibyte characters, these octal escapes are treated as before.
496        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
497        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
498        Unicode string.
500        I have not perpetrated such confusion in PCRE. Up till now, it took just
501        the bottom 8 bits, as in old Perl. I have now made octal escapes with
502        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
503        translate to the appropriate multibyte character.
505    29. Applied some refactoring to reduce the number of warnings from Microsoft
506        and Borland compilers. This has included removing the fudge introduced
507        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
508        a warning about an unused variable.
510    21. PCRE has not included VT (character 0x0b) in the set of whitespace
511        characters since release 4.0, because Perl (from release 5.004) does not.
512        [Or at least, is documented not to: some releases seem to be in conflict
513        with the documentation.] However, when a pattern was studied with
514        pcre_study() and all its branches started with \s, PCRE still included VT
515        as a possible starting character. Of course, this did no harm; it just
516        caused an unnecessary match attempt.
518    22. Removed a now-redundant internal flag bit that recorded the fact that case
519        dependency changed within the pattern. This was once needed for "required
520        byte" processing, but is no longer used. This recovers a now-scarce options
521        bit. Also moved the least significant internal flag bit to the most-
522        significant bit of the word, which was not previously used (hangover from
523        the days when it was an int rather than a uint) to free up another bit for
524        the future.
526    23. Added support for CRLF line endings as well as CR and LF. As well as the
527        default being selectable at build time, it can now be changed at runtime
528        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
529        specify that it is scanning data with non-default line endings.
531    24. Changed the definition of CXXLINK to make it agree with the definition of
532        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
534    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
535        recursions. This makes a big different to stack usage for some patterns.
537    26. If a subpattern containing a named recursion or subroutine reference such
538        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
539        the space required for the compiled pattern went wrong and gave too small a
540        value. Depending on the environment, this could lead to "Failed: internal
541        error: code overflow at offset 49" or "glibc detected double free or
542        corruption" errors.
544    27. Applied patches from Google (a) to support the new newline modes and (b) to
545        advance over multibyte UTF-8 characters in GlobalReplace.
547    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
548        difference for some implementation of PCRE in some Windows version.
550    29. Added some extra testing facilities to pcretest:
552        \q<number>   in a data line sets the "match limit" value
553        \Q<number>   in a data line sets the "match recursion limt" value
554        -S <number>  sets the stack size, where <number> is in megabytes
556        The -S option isn't available for Windows.
559    Version 6.6 06-Feb-06
560    ---------------------
562     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
563        in pcreposix.h. I have copied the definition from pcre.h.
565     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
566        because pcre.h is no longer a built file.
568     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
569        not normally included in the compiled code.
572    Version 6.5 01-Feb-06
573    ---------------------
575     1. When using the partial match feature with pcre_dfa_exec(), it was not
576        anchoring the second and subsequent partial matches at the new starting
577        point. This could lead to incorrect results. For example, with the pattern
578        /1234/, partially matching against "123" and then "a4" gave a match.
580     2. Changes to pcregrep:
582        (a) All non-match returns from pcre_exec() were being treated as failures
583            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
584            error message is output. Some extra information is given for the
585            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
586            probably the only errors that are likely to be caused by users (by
587            specifying a regex that has nested indefinite repeats, for instance).
588            If there are more than 20 of these errors, pcregrep is abandoned.
590        (b) A binary zero was treated as data while matching, but terminated the
591            output line if it was written out. This has been fixed: binary zeroes
592            are now no different to any other data bytes.
594        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
595            used to set a locale for matching. The --locale=xxxx long option has
596            been added (no short equivalent) to specify a locale explicitly on the
597            pcregrep command, overriding the environment variables.
599        (d) When -B was used with -n, some line numbers in the output were one less
600            than they should have been.
602        (e) Added the -o (--only-matching) option.
604        (f) If -A or -C was used with -c (count only), some lines of context were
605            accidentally printed for the final match.
607        (g) Added the -H (--with-filename) option.
609        (h) The combination of options -rh failed to suppress file names for files
610            that were found from directory arguments.
612        (i) Added the -D (--devices) and -d (--directories) options.
614        (j) Added the -F (--fixed-strings) option.
616        (k) Allow "-" to be used as a file name for -f as well as for a data file.
618        (l) Added the --colo(u)r option.
620        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
621            is not present by default.
623     3. A nasty bug was discovered in the handling of recursive patterns, that is,
624        items such as (?R) or (?1), when the recursion could match a number of
625        alternatives. If it matched one of the alternatives, but subsequently,
626        outside the recursion, there was a failure, the code tried to back up into
627        the recursion. However, because of the way PCRE is implemented, this is not
628        possible, and the result was an incorrect result from the match.
630        In order to prevent this happening, the specification of recursion has
631        been changed so that all such subpatterns are automatically treated as
632        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
634     4. I had overlooked the fact that, in some locales, there are characters for
635        which isalpha() is true but neither isupper() nor islower() are true. In
636        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
637        and ordfeminine) are like this. This affected the treatment of \w and \W
638        when they appeared in character classes, but not when they appeared outside
639        a character class. The bit map for "word" characters is now created
640        separately from the results of isalnum() instead of just taking it from the
641        upper, lower, and digit maps. (Plus the underscore character, of course.)
643     5. The above bug also affected the handling of POSIX character classes such as
644        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
645        permanent tables. Instead, the bit maps for such a class were previously
646        created as the appropriate unions of the upper, lower, and digit bitmaps.
647        Now they are created by subtraction from the [[:word:]] class, which has
648        its own bitmap.
650     6. The [[:blank:]] character class matches horizontal, but not vertical space.
651        It is created by subtracting the vertical space characters (\x09, \x0a,
652        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
653        subtraction was done in the overall bitmap for a character class, meaning
654        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
655        be recognized. This bug has been fixed.
657     7. Patches from the folks at Google:
659          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
660          real life, but is still worth protecting against".
662          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
663          regular expressions".
665          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
666          have it.
668          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
669          "configure" and the latter not, in order to fix a problem somebody had
670          with compiling the Arg class on HP-UX.
672          (e) Improve the error-handling of the C++ wrapper a little bit.
674          (f) New tests for checking recursion limiting.
676     8. The pcre_memmove() function, which is used only if the environment does not
677        have a standard memmove() function (and is therefore rarely compiled),
678        contained two bugs: (a) use of int instead of size_t, and (b) it was not
679        returning a result (though PCRE never actually uses the result).
681     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
682        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
683        returned instead of calling malloc() with an overflowing number that would
684        most likely cause subsequent chaos.
686    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
688    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
689        with this option is matched, the nmatch and pmatch options of regexec() are
690        ignored.
692    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
693        provided in case anyone wants to the the POSIX interface with UTF-8
694        strings.
696    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
697        C++ linking (needed for some HP-UX environments).
699    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
700        (unused parameter) and in the pcre_printint() function (omitted "default"
701        switch label when the default is to do nothing).
703    15. Added some code to make it possible, when PCRE is compiled as a C++
704        library, to replace subject pointers for pcre_exec() with a smart pointer
705        class, thus making it possible to process discontinuous strings.
707    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
708        much the same function. They were added by different people who were trying
709        to make PCRE easy to compile on non-Unix systems. It has been suggested
710        that PCRE_EXPORT be abolished now that there is more automatic apparatus
711        for compiling on Windows systems. I have therefore replaced it with
712        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
713        defaults to "extern" for C or "extern C" for C++, which works fine on
714        Unix-like systems. It is now possible to override the value of PCRE_DATA_
715        SCOPE with something explicit in config.h. In addition:
717        (a) pcreposix.h still had just "extern" instead of either of these macros;
718            I have replaced it with PCRE_DATA_SCOPE.
720        (b) Functions such as _pcre_xclass(), which are internal to the library,
721            but external in the C sense, all had PCRE_EXPORT in their definitions.
722            This is apparently wrong for the Windows case, so I have removed it.
723            (It makes no difference on Unix-like systems.)
725    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
726        of recursive calls to match(). This is different to MATCH_LIMIT because
727        that limits the total number of calls to match(), not all of which increase
728        the depth of recursion. Limiting the recursion depth limits the amount of
729        stack (or heap if NO_RECURSE is set) that is used. The default can be set
730        when PCRE is compiled, and changed at run time. A patch from Google adds
731        this functionality to the C++ interface.
733    18. Changes to the handling of Unicode character properties:
735        (a) Updated the table to Unicode 4.1.0.
737        (b) Recognize characters that are not in the table as "Cn" (undefined).
739        (c) I revised the way the table is implemented to a much improved format
740            which includes recognition of ranges. It now supports the ranges that
741            are defined in UnicodeData.txt, and it also amalgamates other
742            characters into ranges. This has reduced the number of entries in the
743            table from around 16,000 to around 3,000, thus reducing its size
744            considerably. I realized I did not need to use a tree structure after
745            all - a binary chop search is just as efficient. Having reduced the
746            number of entries, I extended their size from 6 bytes to 8 bytes to
747            allow for more data.
749        (d) Added support for Unicode script names via properties such as \p{Han}.
751    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
752        matching that character.
754    20. When matching a repeated Unicode property with a minimum greater than zero,
755        (for example \pL{2,}), PCRE could look past the end of the subject if it
756        reached it while seeking the minimum number of characters. This could
757        happen only if some of the characters were more than one byte long, because
758        there is a check for at least the minimum number of bytes.
760    21. Refactored the implementation of \p and \P so as to be more general, to
761        allow for more different types of property in future. This has changed the
762        compiled form incompatibly. Anybody with saved compiled patterns that use
763        \p or \P will have to recompile them.
765    22. Added "Any" and "L&" to the supported property types.
767    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
768        but give a compile time error if the value is greater than 0xff.
770    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
771        accidentally not being installed or uninstalled.
773    25. The pcre.h file was built from pcre.h.in, but the only changes that were
774        made were to insert the current release number. This seemed silly, because
775        it made things harder for people building PCRE on systems that don't run
776        "configure". I have turned pcre.h into a distributed file, no longer built
777        by "configure", with the version identification directly included. There is
778        no longer a pcre.h.in file.
780        However, this change necessitated a change to the pcre-config script as
781        well. It is built from pcre-config.in, and one of the substitutions was the
782        release number. I have updated configure.ac so that ./configure now finds
783        the release number by grepping pcre.h.
785    26. Added the ability to run the tests under valgrind.
788    Version 6.4 05-Sep-05
789    ---------------------
791     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
792        "--" to be printed when multiple files were scanned, even when none of the
793        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
794        consider it to be a bug, and have restored the previous behaviour.
796     2. A couple of code tidies to get rid of compiler warnings.
798     3. The pcretest program used to cheat by referring to symbols in the library
799        whose names begin with _pcre_. These are internal symbols that are not
800        really supposed to be visible externally, and in some environments it is
801        possible to suppress them. The cheating is now confined to including
802        certain files from the library's source, which is a bit cleaner.
804     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
805        file's purpose clearer.
807     5. Reorganized pcre_ucp_findchar().
810    Version 6.3 15-Aug-05
811    ---------------------
813     1. The file libpcre.pc.in did not have general read permission in the tarball.
815     2. There were some problems when building without C++ support:
817        (a) If C++ support was not built, "make install" and "make test" still
818            tried to test it.
820        (b) There were problems when the value of CXX was explicitly set. Some
821            changes have been made to try to fix these, and ...
823        (c) --disable-cpp can now be used to explicitly disable C++ support.
825        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
826            backslash in a target when C++ was disabled. This confuses some
827            versions of "make", apparently. Using an intermediate variable solves
828            this. (Same for CPP_LOBJ.)
830     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
831        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
832        necessary on certain architectures.
834     4. Added a setting of -export-symbols-regex to the link command to remove
835        those symbols that are exported in the C sense, but actually are local
836        within the library, and not documented. Their names all begin with
837        "_pcre_". This is not a perfect job, because (a) we have to except some
838        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
839        available (and never for static libraries). I have made a note to try to
840        find a way round (a) in the future.
843    Version 6.2 01-Aug-05
844    ---------------------
846     1. There was no test for integer overflow of quantifier values. A construction
847        such as {1111111111111111} would give undefined results. What is worse, if
848        a minimum quantifier for a parenthesized subpattern overflowed and became
849        negative, the calculation of the memory size went wrong. This could have
850        led to memory overwriting.
852     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
854     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
855        operating environments where this matters.
857     4. Applied Giuseppe Maxia's patch to add additional features for controlling
858        PCRE options from within the C++ wrapper.
860     5. Named capturing subpatterns were not being correctly counted when a pattern
861        was compiled. This caused two problems: (a) If there were more than 100
862        such subpatterns, the calculation of the memory needed for the whole
863        compiled pattern went wrong, leading to an overflow error. (b) Numerical
864        back references of the form \12, where the number was greater than 9, were
865        not recognized as back references, even though there were sufficient
866        previous subpatterns.
868     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
869        versions of gcc, e.g. 2.95.4.
872    Version 6.1 21-Jun-05
873    ---------------------
875     1. There was one reference to the variable "posix" in pcretest.c that was not
876        surrounded by "#if !defined NOPOSIX".
878     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
879        the cross-check on the old pcre_info() function, for the benefit of the
880        cut-down version of PCRE that is currently imported into Exim.
882     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
883        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
884        patterns that start (?i) but I don't think that matters. The use of (?i) is
885        just an example; this all applies to the other options as well.
887     4. Since libtool seems to echo the compile commands it is issuing, the output
888        from "make" can be reduced a bit by putting "@" in front of each libtool
889        compile command.
891     5. Patch from the folks at Google for configure.in to be a bit more thorough
892        in checking for a suitable C++ installation before trying to compile the
893        C++ stuff. This should fix a reported problem when a compiler was present,
894        but no suitable headers.
896     6. The man pages all had just "PCRE" as their title. I have changed them to
897        be the relevant file name. I have also arranged that these names are
898        retained in the file doc/pcre.txt, which is a concatenation in text format
899        of all the man pages except the little individual ones for each function.
901     7. The NON-UNIX-USE file had not been updated for the different set of source
902        files that come with release 6. I also added a few comments about the C++
903        wrapper.
906    Version 6.0 07-Jun-05
907    ---------------------
909     1. Some minor internal re-organization to help with my DFA experiments.
911     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
912        didn't matter for the library itself when fully configured, but did matter
913        when compiling without UCP support, or within Exim, where the ucp files are
914        not imported.
916     3. Refactoring of the library code to split up the various functions into
917        different source modules. The addition of the new DFA matching code (see
918        below) to a single monolithic source would have made it really too
919        unwieldy, quite apart from causing all the code to be include in a
920        statically linked application, when only some functions are used. This is
921        relevant even without the DFA addition now that patterns can be compiled in
922        one application and matched in another.
924        The downside of splitting up is that there have to be some external
925        functions and data tables that are used internally in different modules of
926        the library but which are not part of the API. These have all had their
927        names changed to start with "_pcre_" so that they are unlikely to clash
928        with other external names.
930     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
931        a different (DFA) algorithm. Although it is slower than the original
932        function, it does have some advantages for certain types of matching
933        problem.
935     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
936        including restarting after a partial match.
938     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
939        defined when compiling for Windows was sent to me. I have put it into the
940        code, though I have no means of testing or verifying it.
942     7. Added the pcre_refcount() auxiliary function.
944     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
945        match before or at the first newline in the subject string. In pcretest,
946        the /f option on a pattern can be used to set this.
948     9. A repeated \w when used in UTF-8 mode with characters greater than 256
949        would behave wrongly. This has been present in PCRE since release 4.0.
951    10. A number of changes to the pcregrep command:
953        (a) Refactored how -x works; insert ^(...)$ instead of setting
954            PCRE_ANCHORED and checking the length, in preparation for adding
955            something similar for -w.
957        (b) Added the -w (match as a word) option.
959        (c) Refactored the way lines are read and buffered so as to have more
960            than one at a time available.
962        (d) Implemented a pcregrep test script.
964        (e) Added the -M (multiline match) option. This allows patterns to match
965            over several lines of the subject. The buffering ensures that at least
966            8K, or the rest of the document (whichever is the shorter) is available
967            for matching (and similarly the previous 8K for lookbehind assertions).
969        (f) Changed the --help output so that it now says
971              -w, --word-regex(p)
973            instead of two lines, one with "regex" and the other with "regexp"
974            because that confused at least one person since the short forms are the
975            same. (This required a bit of code, as the output is generated
976            automatically from a table. It wasn't just a text change.)
978        (g) -- can be used to terminate pcregrep options if the next thing isn't an
979            option but starts with a hyphen. Could be a pattern or a path name
980            starting with a hyphen, for instance.
982        (h) "-" can be given as a file name to represent stdin.
984        (i) When file names are being printed, "(standard input)" is used for
985            the standard input, for compatibility with GNU grep. Previously
986            "<stdin>" was used.
988        (j) The option --label=xxx can be used to supply a name to be used for
989            stdin when file names are being printed. There is no short form.
991        (k) Re-factored the options decoding logic because we are going to add
992            two more options that take data. Such options can now be given in four
993            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
995        (l) Added the -A, -B, and -C options for requesting that lines of context
996            around matches be printed.
998        (m) Added the -L option to print the names of files that do not contain
999            any matching lines, that is, the complement of -l.
1001        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1002            continue to scan other files.
1004        (o) The -s option was incorrectly implemented. For compatibility with other
1005            greps, it now suppresses the error message for a non-existent or non-
1006            accessible file (but not the return code). There is a new option called
1007            -q that suppresses the output of matching lines, which was what -s was
1008            previously doing.
1010        (p) Added --include and --exclude options to specify files for inclusion
1011            and exclusion when recursing.
1013    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1014        Hopefully, it now does.
1016    12. Missing cast in pcre_study().
1018    13. Added an "uninstall" target to the makefile.
1020    14. Replaced "extern" in the function prototypes in Makefile.in with
1021        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1022        world, but is set differently for Windows.
1024    15. Added a second compiling function called pcre_compile2(). The only
1025        difference is that it has an extra argument, which is a pointer to an
1026        integer error code. When there is a compile-time failure, this is set
1027        non-zero, in addition to the error test pointer being set to point to an
1028        error message. The new argument may be NULL if no error number is required
1029        (but then you may as well call pcre_compile(), which is now just a
1030        wrapper). This facility is provided because some applications need a
1031        numeric error indication, but it has also enabled me to tidy up the way
1032        compile-time errors are handled in the POSIX wrapper.
1034    16. Added VPATH=.libs to the makefile; this should help when building with one
1035        prefix path and installing with another. (Or so I'm told by someone who
1036        knows more about this stuff than I do.)
1038    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1039        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1040        match everything, including newlines. This is not POSIX-compatible, but
1041        somebody wanted the feature. From pcretest it can be activated by using
1042        both the P and the s flags.
1044    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1046    19. libpcre.pc was being incorrectly installed as executable.
1048    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1049        it now also looks for '\r' so that it will work unmodified on Windows.
1051    21. Added Google's contributed C++ wrapper to the distribution.
1053    22. Added some untidy missing memory free() calls in pcretest, to keep
1054        Electric Fence happy when testing.
1058    Version 5.0 13-Sep-04
1059    ---------------------
1061     1. Internal change: literal characters are no longer packed up into items
1062        containing multiple characters in a single byte-string. Each character
1063        is now matched using a separate opcode. However, there may be more than one
1064        byte in the character in UTF-8 mode.
1066     2. The pcre_callout_block structure has two new fields: pattern_position and
1067        next_item_length. These contain the offset in the pattern to the next match
1068        item, and its length, respectively.
1070     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1071        insertion of callouts before each pattern item. Added the /C option to
1072        pcretest to make use of this.
1074     4. On the advice of a Windows user, the lines
1076          #if defined(_WIN32) || defined(WIN32)
1077          _setmode( _fileno( stdout ), 0x8000 );
1078          #endif  /* defined(_WIN32) || defined(WIN32) */
1080        have been added to the source of pcretest. This apparently does useful
1081        magic in relation to line terminators.
1083     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1084        for the benefit of those environments where the "b" makes a difference.
1086     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1087        to know about it. I have put a hack into configure.in that adds in code
1088        to set GCC=yes if CC=icc. This seems to end up at a point in the
1089        generated configure script that is early enough to affect the setting of
1090        compiler options, which is what is needed, but I have no means of testing
1091        whether it really works. (The user who reported this had patched the
1092        generated configure script, which of course I cannot do.)
1094        LATER: After change 22 below (new libtool files), the configure script
1095        seems to know about icc (and also ecc). Therefore, I have commented out
1096        this hack in configure.in.
1098     7. Added support for pkg-config (2 patches were sent in).
1100     8. Negated POSIX character classes that used a combination of internal tables
1101        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1102        [[:^ascii]]. Typically, they would match almost any characters. The other
1103        POSIX classes were not broken in this way.
1105     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1106        to find the match, as PCRE was deluded into thinking that the match had to
1107        start at the start point or following a newline. The same bug applied to
1108        patterns with negative forward assertions or any backward assertions
1109        preceding ".*" at the start, unless the pattern required a fixed first
1110        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1112    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1113        starting at the last subject character, bytes beyond the end of the subject
1114        string were read.
1116    11. Renamed the variable "class" as "classbits" to make life easier for C++
1117        users. (Previously there was a macro definition, but it apparently wasn't
1118        enough.)
1120    12. Added the new field "tables" to the extra data so that tables can be passed
1121        in at exec time, or the internal tables can be re-selected. This allows
1122        a compiled regex to be saved and re-used at a later time by a different
1123        program that might have everything at different addresses.
1125    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1126        -R library as well as a -L library.
1128    14. The debugging options of pcretest (-d on the command line or D on a
1129        pattern) showed incorrect output for anything following an extended class
1130        that contained multibyte characters and which was followed by a quantifier.
1132    15. Added optional support for general category Unicode character properties
1133        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1134        support. It adds about 90K to the size of the library. The meanings of the
1135        inbuilt class escapes such as \d and \s have NOT been changed.
1137    16. Updated pcredemo.c to include calls to free() to release the memory for the
1138        compiled pattern.
1140    17. The generated file chartables.c was being created in the source directory
1141        instead of in the building directory. This caused the build to fail if the
1142        source directory was different from the building directory, and was
1143        read-only.
1145    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1146        file. No doubt somebody will tell me if they don't make sense... Also added
1147        Dan Mooney's comments about building on OpenVMS.
1149    19. Added support for partial matching via the PCRE_PARTIAL option for
1150        pcre_exec() and the \P data escape in pcretest.
1152    20. Extended pcretest with 3 new pattern features:
1154        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1155              write the compiled pattern to the file whose name is "rest-of-line".
1156              This is a straight binary dump of the data, with the saved pointer to
1157              the character tables forced to be NULL. The study data, if any, is
1158              written too. After writing, pcretest reads a new pattern.
1160        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1161              compiled pattern from the given file. There must not be any
1162              occurrences of "<" in the file name (pretty unlikely); if there are,
1163              pcretest will instead treat the initial "<" as a pattern delimiter.
1164              After reading in the pattern, pcretest goes on to read data lines as
1165              usual.
1167        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1168              and 16-bit fields in a compiled pattern, to simulate a pattern that
1169              was compiled on a host of opposite endianness.
1171    21. The pcre-exec() function can now cope with patterns that were compiled on
1172        hosts of opposite endianness, with this restriction:
1174          As for any compiled expression that is saved and used later, the tables
1175          pointer field cannot be preserved; the extra_data field in the arguments
1176          to pcre_exec() should be used to pass in a tables address if a value
1177          other than the default internal tables were used at compile time.
1179    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1180        now diagnosed as an error. Previously, most of the time, a negative number
1181        would have been treated as zero, but if in addition "ovector" was passed as
1182        NULL, a crash could occur.
1184    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1185        new versions from the libtool 1.5 distribution (the last one is a copy of
1186        a file called libtool.m4). This seems to have fixed the need to patch
1187        "configure" to support Darwin 1.3 (which I used to do). However, I still
1188        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1189        workstation).
1191    24. Changed the PCRE licence to be the more standard "BSD" licence.
1194    Version 4.5 01-Dec-03
1195    ---------------------
1197     1. There has been some re-arrangement of the code for the match() function so
1198        that it can be compiled in a version that does not call itself recursively.
1199        Instead, it keeps those local variables that need separate instances for
1200        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1201        needs to "recurse". Keeping track of where control must go is done by means
1202        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1203        hide most of the details from the main code, and operates only if
1204        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1205        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1206        operating.
1208        To make it easier for callers to provide specially tailored get/free
1209        functions for this usage, two new functions, pcre_stack_malloc, and
1210        pcre_stack_free, are used. They are always called in strict stacking order,
1211        and the size of block requested is always the same.
1213        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1214        PCRE has been compiled to use the stack or the heap for recursion. The
1215        -C option of pcretest uses this to show which version is compiled.
1217        A new data escape \S, is added to pcretest; it causes the amounts of store
1218        obtained and freed by both kinds of malloc/free at match time to be added
1219        to the output.
1221     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1222        what's available on my current Linux desktop machine.
1224     3. When matching a UTF-8 string, the test for a valid string at the start has
1225        been extended. If start_offset is not zero, PCRE now checks that it points
1226        to a byte that is the start of a UTF-8 character. If not, it returns
1227        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1228        this is necessary because there may be backward assertions in the pattern.
1229        When matching the same subject several times, it may save resources to use
1230        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1232     4. The code for checking the validity of UTF-8 strings has been tightened so
1233        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1234        containing "overlong sequences".
1236     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1237        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1238        should have been "&", but it just so happened that all the cases this let
1239        through by mistake were picked up later in the function.
1241     6. I had used a variable called "isblank" - this is a C99 function, causing
1242        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1244     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1245        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1246        so the version is shown; (c) stop "make test" echoing "./RunTest".
1248     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1250     9. The prototype for memmove() for systems that don't have it was using
1251        size_t, but the inclusion of the header that defines size_t was later. I've
1252        moved the #includes for the C headers earlier to avoid this.
1254    10. Added some adjustments to the code to make it easier to compiler on certain
1255        special systems:
1257          (a) Some "const" qualifiers were missing.
1258          (b) Added the macro EXPORT before all exported functions; by default this
1259              is defined to be empty.
1260          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1261              that it reads its output file name as an argument instead of writing
1262              to the standard output and assuming this can be redirected.
1264    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1265        class containing characters with values greater than 255, PCRE compilation
1266        went into a loop.
1268    12. A recursive reference to a subpattern that was within another subpattern
1269        that had a minimum quantifier of zero caused PCRE to crash. For example,
1270        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1271        recursion. If the recursively-called subpattern itself had a zero repeat,
1272        that was OK.
1274    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1275        buffer into which it was copied (for escape processing) was still set at
1276        1024, so long lines caused crashes.
1278    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1279        "internal error: code overflow...". This applied to any character class
1280        that was followed by a possessive quantifier.
1282    15. Modified the Makefile to add libpcre.la as a prerequisite for
1283        libpcreposix.la because I was told this is needed for a parallel build to
1284        work.
1286    16. If a pattern that contained .* following optional items at the start was
1287        studied, the wrong optimizing data was generated, leading to matching
1288        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1289        matching string must start with a or b or c. The correct conclusion for
1290        this pattern is that a match can start with any character.
1293    Version 4.4 13-Aug-03
1294    ---------------------
1296     1. In UTF-8 mode, a character class containing characters with values between
1297        127 and 255 was not handled correctly if the compiled pattern was studied.
1298        In fixing this, I have also improved the studying algorithm for such
1299        classes (slightly).
1301     2. Three internal functions had redundant arguments passed to them. Removal
1302        might give a very teeny performance improvement.
1304     3. Documentation bug: the value of the capture_top field in a callout is *one
1305        more than* the number of the hightest numbered captured substring.
1307     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1308        in incorrectly linking with a previously installed version. They now link
1309        explicitly with libpcre.la.
1311     5. configure.in no longer needs to recognize Cygwin specially.
1313     6. A problem in pcre.in for Windows platforms is fixed.
1315     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1316        pcretest, it used to include the size of the study block as part of its
1317        output. Unfortunately, the structure contains a field that has a different
1318        size on different hardware architectures. This meant that the tests that
1319        showed this size failed. As the block is currently always of a fixed size,
1320        this information isn't actually particularly useful in pcretest output, so
1321        I have just removed it.
1323     8. Three pre-processor statements accidentally did not start in column 1.
1324        Sadly, there are *still* compilers around that complain, even though
1325        standard C has not required this for well over a decade. Sigh.
1327     9. In pcretest, the code for checking callouts passed small integers in the
1328        callout_data field, which is a void * field. However, some picky compilers
1329        complained about the casts involved for this on 64-bit systems. Now
1330        pcretest passes the address of the small integer instead, which should get
1331        rid of the warnings.
1333    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1334        both compile and run time, and gives an error if an invalid UTF-8 sequence
1335        is found. There is a option for disabling this check in cases where the
1336        string is known to be correct and/or the maximum performance is wanted.
1338    11. In response to a bug report, I changed one line in Makefile.in from
1340            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1341        to
1342            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1344        to look similar to other lines, but I have no way of telling whether this
1345        is the right thing to do, as I do not use Windows. No doubt I'll get told
1346        if it's wrong...
1349    Version 4.3 21-May-03
1350    ---------------------
1352    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1353       Makefile.
1355    2. Some refactoring to improve the quality of the code:
1357       (i)   The utf8_table... variables are now declared "const".
1359       (ii)  The code for \cx, which used the "case flipping" table to upper case
1360             lower case letters, now just substracts 32. This is ASCII-specific,
1361             but the whole concept of \cx is ASCII-specific, so it seems
1362             reasonable.
1364       (iii) PCRE was using its character types table to recognize decimal and
1365             hexadecimal digits in the pattern. This is silly, because it handles
1366             only 0-9, a-f, and A-F, but the character types table is locale-
1367             specific, which means strange things might happen. A private
1368             table is now used for this - though it costs 256 bytes, a table is
1369             much faster than multiple explicit tests. Of course, the standard
1370             character types table is still used for matching digits in subject
1371             strings against \d.
1373       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1374             ending in _t are). So I've renamed it as ESC_tee.
1376    3. The first argument for regexec() in the POSIX wrapper should have been
1377       defined as "const".
1379    4. Changed pcretest to use malloc() for its buffers so that they can be
1380       Electric Fenced for debugging.
1382    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1383       to read one or more bytes before the start of the subject string. Often this
1384       had no effect on PCRE's behaviour, but in some circumstances it could
1385       provoke a segmentation fault.
1387    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1388       to try to read one or more bytes before the start of the subject string.
1390    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1391       UTF-8 support could misbehave in various ways if the subject string
1392       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1393       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1394       back over UTF-8 characters.)
1397    Version 4.2 14-Apr-03
1398    ---------------------
1400    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1402    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1403         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1404         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1405         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1406         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1407           and BUILD_EXEEXT
1408         Note: automatic setting of the BUILD variables is not yet working
1409         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1410           compile-time but not at link-time
1411         [LINK]: use for linking executables only
1412         make different versions for Windows and non-Windows
1413         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1414           libraries
1415         [LINK_FOR_BUILD]: new variable
1416         [OBJEXT]: use throughout
1417         [EXEEXT]: use throughout
1418         <winshared>: new target
1419         <wininstall>: new target
1420         <dftables.o>: use native compiler
1421         <dftables>: use native linker
1422         <install>: handle Windows platform correctly
1423         <clean>: ditto
1424         <check>: ditto
1425         copy DLL to top builddir before testing
1427       As part of these changes, -no-undefined was removed again. This was reported
1428       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1429       in any case.
1431    3. Some tidies to get rid of compiler warnings:
1433       . In the match_data structure, match_limit was an unsigned long int, whereas
1434         match_call_count was an int. I've made them both unsigned long ints.
1436       . In pcretest the fact that a const uschar * doesn't automatically cast to
1437         a void * provoked a warning.
1439       . Turning on some more compiler warnings threw up some "shadow" variables
1440         and a few more missing casts.
1442    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1443       option, a class that contained a single character with a value between 128
1444       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1446    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1447       option, a class that contained several characters, but with at least one
1448       whose value was between 128 and 255 caused PCRE to crash.
1451    Version 4.1 12-Mar-03
1452    ---------------------
1454    1. Compiling with gcc -pedantic found a couple of places where casts were
1455    needed, and a string in dftables.c that was longer than standard compilers are
1456    required to support.
1458    2. Compiling with Sun's compiler found a few more places where the code could
1459    be tidied up in order to avoid warnings.
1461    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1462    first of these names is deprecated in the latest Autoconf in favour of the name
1463    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1464    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1465    analogy I have changed it to CFLAGS_FOR_BUILD.
1467    4. Added -no-undefined to the linking command in the Makefile, because this is
1468    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1469    linking step for the pcreposix library.
1471    5. PCRE was failing to diagnose the case of two named groups with the same
1472    name.
1474    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1475    literal character that is needed in the subject for a match, and scans along to
1476    ensure that it is present before embarking on the full matching process. This
1477    saves time in cases of nested unlimited repeats that are never going to match.
1478    Problem: the scan can take a lot of time if the subject is very long (e.g.
1479    megabytes), thus penalizing straightforward matches. It is now done only if the
1480    amount of subject to be scanned is less than 1000 bytes.
1482    7. A lesser problem with the same optimization is that it was recording the
1483    first character of an anchored pattern as "needed", thus provoking a search
1484    right along the subject, even when the first match of the pattern was going to
1485    fail. The "needed" character is now not set for anchored patterns, unless it
1486    follows something in the pattern that is of non-fixed length. Thus, it still
1487    fulfils its original purpose of finding quick non-matches in cases of nested
1488    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1491    Version 4.0 17-Feb-03
1492    ---------------------
1494    1. If a comment in an extended regex that started immediately after a meta-item
1495    extended to the end of string, PCRE compiled incorrect data. This could lead to
1496    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1498    2. Moved to autoconf 2.53 and libtool 1.4.2.
1500    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1501    the special perltest8 script is no longer needed - all the tests can be run
1502    from a single perltest script.
1504    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1505    by \s. It has now been removed in PCRE. This means it isn't recognized as
1506    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1507    class [:space:] *does* include VT, thereby creating a mess.
1509    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1510    space and tab.
1512    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1513    its new features into the main test script, reducing the number of scripts.
1515    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1516    were backward compatible, and made the (?i) apply to the whole pattern, as if
1517    /i were given. Now it behaves more logically, and applies the option setting
1518    only to what follows. PCRE has been changed to follow suit. However, if it
1519    finds options settings right at the start of the pattern, it extracts them into
1520    the global options, as before. Thus, they show up in the info data.
1522    8. Added support for the \Q...\E escape sequence. Characters in between are
1523    treated as literals. This is slightly different from Perl in that $ and @ are
1524    also handled as literals inside the quotes. In Perl, they will cause variable
1525    interpolation. Note the following examples:
1527        Pattern            PCRE matches      Perl matches
1529        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
1530        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
1531        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
1533    For compatibility with Perl, \Q...\E sequences are recognized inside character
1534    classes as well as outside them.
1536    9. Re-organized 3 code statements in pcretest to avoid "overflow in
1537    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1538    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1539    signed/unsigned warnings.
1541    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1542    option for pcretest, so I've replaced it by a simple function that does just
1543    that job.
1545    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1546    "pcregrep -".
1548    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1549    Java package. This provides some syntactic sugar for simple cases of what my
1550    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1551    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1552    item, you can use this simplified notation. Note that only makes sense with
1553    greedy quantifiers. Consequently, the use of the possessive quantifier forces
1554    greediness, whatever the setting of the PCRE_UNGREEDY option.
1556    13. A change of greediness default within a pattern was not taking effect at
1557    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1558    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1559    was abstracted outside.
1561    14. PCRE now supports the \G assertion. It is true when the current matching
1562    position is at the start point of the match. This differs from \A when the
1563    starting offset is non-zero. Used with the /g option of pcretest (or similar
1564    code), it works in the same way as it does for Perl's /g option. If all
1565    alternatives of a regex begin with \G, the expression is anchored to the start
1566    match position, and the "anchored" flag is set in the compiled expression.
1568    15. Some bugs concerning the handling of certain option changes within patterns
1569    have been fixed. These applied to options other than (?ims). For example,
1570    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1571    been the other way round. Some of this was related to change 7 above.
1573    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1574    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1575    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1576    POSIX classes only within a class (e.g. /[[:alpha:]]/).
1578    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1579    mode. Unlike ".", it always matches newline, whatever the setting of
1580    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1581    assertions. Perl allows it, but it doesn't (in general) work because it can't
1582    calculate the length of the lookbehind. At least, that's the case for Perl
1583    5.8.0 - I've been told they are going to document that it doesn't work in
1584    future.
1586    18. Added an error diagnosis for escapes that PCRE does not support: these are
1587    \L, \l, \N, \P, \p, \U, \u, and \X.
1589    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1590    reading past the end of the pattern in cases such as /[abcd/.
1592    20. PCRE was getting more memory than necessary for patterns with classes that
1593    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1595    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1596    compiling PCRE for use with Virtual Pascal.
1598    22. Small fix to the Makefile to make it work properly if the build is done
1599    outside the source tree.
1601    23. Added a new extension: a condition to go with recursion. If a conditional
1602    subpattern starts with (?(R) the "true" branch is used if recursion has
1603    happened, whereas the "false" branch is used only at the top level.
1605    24. When there was a very long string of literal characters (over 255 bytes
1606    without UTF support, over 250 bytes with UTF support), the computation of how
1607    much memory was required could be incorrect, leading to segfaults or other
1608    strange effects.
1610    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1611    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1612    there was a subsequent back reference to those brackets. This meant that, for
1613    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1614    possible to check for precisely this case. All we can do is abandon the
1615    optimization if .* occurs inside capturing brackets when there are any back
1616    references whatsoever. (See below for a better fix that came later.)
1618    26. The handling of the optimization for finding the first character of a
1619    non-anchored pattern, and for finding a character that is required later in the
1620    match were failing in some cases. This didn't break the matching; it just
1621    failed to optimize when it could. The way this is done has been re-implemented.
1623    27. Fixed typo in error message for invalid (?R item (it said "(?p").
1625    28. Added a new feature that provides some of the functionality that Perl
1626    provides with (?{...}). The facility is termed a "callout". The way it is done
1627    in PCRE is for the caller to provide an optional function, by setting
1628    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1629    global variable. By default it is unset, which disables all calling out. To get
1630    the function called, the regex must include (?C) at appropriate points. This
1631    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1632    This provides a means of identifying different callout points. When PCRE
1633    reaches such a point in the regex, if pcre_callout has been set, the external
1634    function is called. It is provided with data in a structure called
1635    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1636    matching continues; if it returns a non-zero value, the match at the current
1637    point fails. However, backtracking will occur if possible. [This was changed
1638    later and other features added - see item 49 below.]
1640    29. pcretest is upgraded to test the callout functionality. It provides a
1641    callout function that displays information. By default, it shows the start of
1642    the match and the current position in the text. There are some new data escapes
1643    to vary what happens:
1645        \C+         in addition, show current contents of captured substrings
1646        \C-         do not supply a callout function
1647        \C!n        return 1 when callout number n is reached
1648        \C!n!m      return 1 when callout number n is reached for the mth time
1650    30. If pcregrep was called with the -l option and just a single file name, it
1651    output "<stdin>" if a match was found, instead of the file name.
1653    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1654    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1655    pcre_exec(). This saves a malloc/free per call. The default value of
1656    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1657    when configuring.
1659    32. The default maximum size of a compiled pattern is 64K. There have been a
1660    few cases of people hitting this limit. The code now uses macros to handle the
1661    storing of links as offsets within the compiled pattern. It defaults to 2-byte
1662    links, but this can be changed to 3 or 4 bytes by --with-link-size when
1663    configuring. Tests 2 and 5 work only with 2-byte links because they output
1664    debugging information about compiled patterns.
1666    33. Internal code re-arrangements:
1668    (a) Moved the debugging function for printing out a compiled regex into
1669        its own source file (printint.c) and used #include to pull it into
1670        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1671        separate copies.
1673    (b) Defined the list of op-code names for debugging as a macro in
1674        internal.h so that it is next to the definition of the opcodes.
1676    (c) Defined a table of op-code lengths for simpler skipping along compiled
1677        code. This is again a macro in internal.h so that it is next to the
1678        definition of the opcodes.
1680    34. Added support for recursive calls to individual subpatterns, along the
1681    lines of Robin Houston's patch (but implemented somewhat differently).
1683    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1684    allow it to read and process whole directories in Win32. This code was
1685    contributed by Lionel Fourquaux; it has not been tested by me.
1687    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1688    used to name a group. Names consist of alphanumerics and underscores, and must
1689    be unique. Back references use the syntax (?P=name) and recursive calls use
1690    (?P>name) which is a PCRE extension to the Python extension. Groups still have
1691    numbers. The function pcre_fullinfo() can be used after compilation to extract
1692    a name/number map. There are three relevant calls:
1694      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
1695      PCRE_INFO_NAMECOUNT            yields the number of entries
1696      PCRE_INFO_NAMETABLE            yields a pointer to the map.
1698    The map is a vector of fixed-size entries. The size of each entry depends on
1699    the length of the longest name used. The first two bytes of each entry are the
1700    group number, most significant byte first. There follows the corresponding
1701    name, zero terminated. The names are in alphabetical order.
1703    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1704    case instead of 255. Making it the same both with and without UTF-8 support
1705    means that the same test output works with both.
1707    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1708    calling malloc() with a zero argument.
1710    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1711    optimization. I've improved things by keeping a bitmap of backreferences with
1712    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1713    fact referenced, the optimization can be applied. It is unlikely that a
1714    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1715    the match to follow \n) will appear inside brackets with a number greater than
1716    31, but if it does, any back reference > 31 suppresses the optimization.
1718    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1719    of disabling numbered capturing parentheses. Any opening parenthesis that is
1720    not followed by ? behaves as if it were followed by ?: but named parentheses
1721    can still be used for capturing (and they will acquire numbers in the usual
1722    way).
1724    41. Redesigned the return codes from the match() function into yes/no/error so
1725    that errors can be passed back from deep inside the nested calls. A malloc
1726    failure while inside a recursive subpattern call now causes the
1727    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1729    42. It is now possible to set a limit on the number of times the match()
1730    function is called in a call to pcre_exec(). This facility makes it possible to
1731    limit the amount of recursion and backtracking, though not in a directly
1732    obvious way, because the match() function is used in a number of different
1733    circumstances. The count starts from zero for each position in the subject
1734    string (for non-anchored patterns). The default limit is, for compatibility, a
1735    large number, namely 10 000 000. You can change this in two ways:
1737    (a) When configuring PCRE before making, you can use --with-match-limit=n
1738        to set a default value for the compiled library.
1740    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1741        a different value is set. See 45 below.
1743    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1745    43. Added a new function pcre_config(int, void *) to enable run-time extraction
1746    of things that can be changed at compile time. The first argument specifies
1747    what is wanted and the second points to where the information is to be placed.
1748    The current list of available information is:
1750      PCRE_CONFIG_UTF8
1752    The output is an integer that is set to one if UTF-8 support is available;
1753    otherwise it is set to zero.
1757    The output is an integer that it set to the value of the code that is used for
1758    newline. It is either LF (10) or CR (13).
1762    The output is an integer that contains the number of bytes used for internal
1763    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
1767    The output is an integer that contains the threshold above which the POSIX
1768    interface uses malloc() for output vectors. See item 31 above.
1772    The output is an unsigned integer that contains the default limit of the number
1773    of match() calls in a pcre_exec() execution. See 42 above.
1775    44. pcretest has been upgraded by the addition of the -C option. This causes it
1776    to extract all the available output from the new pcre_config() function, and to
1777    output it. The program then exits immediately.
1779    45. A need has arisen to pass over additional data with calls to pcre_exec() in
1780    order to support additional features. One way would have been to define
1781    pcre_exec2() (for example) with extra arguments, but this would not have been
1782    extensible, and would also have required all calls to the original function to
1783    be mapped to the new one. Instead, I have chosen to extend the mechanism that
1784    is used for passing in "extra" data from pcre_study().
1786    The pcre_extra structure is now exposed and defined in pcre.h. It currently
1787    contains the following fields:
1789      flags         a bitmap indicating which of the following fields are set
1790      study_data    opaque data from pcre_study()
1791      match_limit   a way of specifying a limit on match() calls for a specific
1792                      call to pcre_exec()
1793      callout_data  data for callouts (see 49 below)
1795    The flag bits are also defined in pcre.h, and are
1801    The pcre_study() function now returns one of these new pcre_extra blocks, with
1802    the actual study data pointed to by the study_data field, and the
1803    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
1804    before. That is, this change is entirely upwards-compatible and requires no
1805    change to existing code.
1807    If you want to pass in additional data to pcre_exec(), you can either place it
1808    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
1809    block.
1811    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
1812    data string contains the escape sequence \M, pcretest calls pcre_exec() several
1813    times with different match limits, until it finds the minimum value needed for
1814    pcre_exec() to complete. The value is then output. This can be instructive; for
1815    most simple matches the number is quite small, but for pathological cases it
1816    gets very large very quickly.
1818    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
1819    returns the size of the data block pointed to by the study_data field in a
1820    pcre_extra block, that is, the value that was passed as the argument to
1821    pcre_malloc() when PCRE was getting memory in which to place the information
1822    created by pcre_study(). The fourth argument should point to a size_t variable.
1823    pcretest has been extended so that this information is shown after a successful
1824    pcre_study() call when information about the compiled regex is being displayed.
1826    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
1827    because what follows is always an absolute path. (Later: it turns out that this
1828    is more than cosmetic for MinGW, because it doesn't like empty path
1829    components.)
1831    49. Some changes have been made to the callout feature (see 28 above):
1833    (i)  A callout function now has three choices for what it returns:
1835           0  =>  success, carry on matching
1836         > 0  =>  failure at this point, but backtrack if possible
1837         < 0  =>  serious error, return this value from pcre_exec()
1839         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
1840         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
1841         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
1842         use by callout functions. It will never be used by PCRE itself.
1844    (ii) The pcre_extra structure (see 45 above) has a void * field called
1845         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
1846         pcre_callout_block structure has a field of the same name. The contents of
1847         the field passed in the pcre_extra structure are passed to the callout
1848         function in the corresponding field in the callout block. This makes it
1849         easier to use the same callout-containing regex from multiple threads. For
1850         testing, the pcretest program has a new data escape
1852           \C*n        pass the number n (may be negative) as callout_data
1854         If the callout function in pcretest receives a non-zero value as
1855         callout_data, it returns that value.
1857    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
1858    there were some redundant $(CFLAGS) in commands that are now specified as
1859    $(LINK), which already includes $(CFLAGS).
1861    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
1862    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
1863    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
1864    one-byte characters throughout. Note that case-insensitive matching applies
1865    only to characters whose values are less than 256. PCRE doesn't support the
1866    notion of cases for higher-valued characters.
1868    (i)   A character class whose characters are all within 0-255 is handled as
1869          a bit map, and the map is inverted for negative classes. Previously, a
1870          character > 255 always failed to match such a class; however it should
1871          match if the class was a negative one (e.g. [^ab]). This has been fixed.
1873    (ii)  A negated character class with a single character < 255 is coded as
1874          "not this character" (OP_NOT). This wasn't working properly when the test
1875          character was multibyte, either singly or repeated.
1877    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
1878          mode, for example: \x{100}{2,3}.
1880    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
1881          singly or repeated) now correctly test multibyte characters. However,
1882          PCRE doesn't recognize any characters with values greater than 255 as
1883          digits, spaces, or word characters. Such characters always match \D, \S,
1884          and \W, and never match \d, \s, or \w.
1886    (v)   Classes may now contain characters and character ranges with values
1887          greater than 255. For example: [ab\x{100}-\x{400}].
1889    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
1890          PCRE in UTF-8 mode.
1892    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
1893    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
1894    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
1895    value.)
1897    53. The single man page has become too large. I have therefore split it up into
1898    a number of separate man pages. These also give rise to individual HTML pages;
1899    these are now put in a separate directory, and there is an index.html page that
1900    lists them all. Some hyperlinking between the pages has been installed.
1902    54. Added convenience functions for handling named capturing parentheses.
1904    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
1905    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
1906    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
1907    are faulted.
1909    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
1910    calling configure. These values are used when compiling the dftables.c program
1911    which is run to generate the source of the default character tables. They
1912    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
1913    you will need to set these values.
1915    57. Updated the building process for Windows DLL, as provided by Fred Cox.
1918    Version 3.9 02-Jan-02
1919    ---------------------
1921    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
1923    2. If --disable-static was given, the building process failed when trying to
1924    build pcretest and pcregrep. (For some reason it was using libtool to compile
1925    them, which is not right, as they aren't part of the library.)
1928    Version 3.8 18-Dec-01
1929    ---------------------
1931    1. The experimental UTF-8 code was completely screwed up. It was packing the
1932    bytes in the wrong order. How dumb can you get?
1935    Version 3.7 29-Oct-01
1936    ---------------------
1938    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
1939    This caused pcretest, when used on the test data, to segfault. Unfortunately,
1940    this didn't happen under Solaris 8, where I normally test things.
1942    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
1943    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
1944    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
1945    this fix an hour or so after the initial 3.7 release.)
1948    Version 3.6 23-Oct-01
1949    ---------------------
1951    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
1952    offsets passed as NULL with zero offset count.
1954    2. The config.guess and config.sub files had not been updated when I moved to
1955    the latest autoconf.
1958    Version 3.5 15-Aug-01
1959    ---------------------
1961    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
1962    had been forgotten.
1964    2. By using declared but undefined structures, we can avoid using "void"
1965    definitions in pcre.h while keeping the internal definitions of the structures
1966    private.
1968    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
1969    user point of view, this means that both static and shared libraries are built
1970    by default, but this can be individually controlled. More of the work of
1971    handling this static/shared cases is now inside libtool instead of PCRE's make
1972    file.
1974    4. The pcretest utility is now installed along with pcregrep because it is
1975    useful for users (to test regexs) and by doing this, it automatically gets
1976    relinked by libtool. The documentation has been turned into a man page, so
1977    there are now .1, .txt, and .html versions in /doc.
1979    5. Upgrades to pcregrep:
1980       (i)   Added long-form option names like gnu grep.
1981       (ii)  Added --help to list all options with an explanatory phrase.
1982       (iii) Added -r, --recursive to recurse into sub-directories.
1983       (iv)  Added -f, --file to read patterns from a file.
1985    6. pcre_exec() was referring to its "code" argument before testing that
1986    argument for NULL (and giving an error if it was NULL).
1988    7. Upgraded Makefile.in to allow for compiling in a different directory from
1989    the source directory.
1991    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
1992    options bits, the pointer it was passed was to an int instead of to an unsigned
1993    long int. This mattered only on 64-bit systems.
1995    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
1996    generated) instead of pcre.in, which it its source. Also made the same change
1997    in several of the .c files.
1999    10. A new release of gcc defines printf() as a macro, which broke pcretest
2000    because it had an ifdef in the middle of a string argument for printf(). Fixed
2001    by using separate calls to printf().
2003    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2004    script, to force use of CR or LF instead of \n in the source. On non-Unix
2005    systems, the value can be set in config.h.
2007    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2008    absolute limit. Changed the text of the error message to make this clear, and
2009    likewise updated the man page.
2011    13. The limit of 99 on the number of capturing subpatterns has been removed.
2012    The new limit is 65535, which I hope will not be a "real" limit.
2015    Version 3.4 22-Aug-00
2016    ---------------------
2018    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2020    2. Diagnose condition (?(0) as an error instead of crashing on matching.
2023    Version 3.3 01-Aug-00
2024    ---------------------
2026    1. If an octal character was given, but the value was greater than \377, it
2027    was not getting masked to the least significant bits, as documented. This could
2028    lead to crashes in some systems.
2030    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2031    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2033    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2034    These just pass their arguments on to (pcre_free)(), but they are provided
2035    because some uses of PCRE bind it to non-C systems that can call its functions,
2036    but cannot call free() or pcre_free() directly.
2038    4. Add "make test" as a synonym for "make check". Corrected some comments in
2039    the Makefile.
2041    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2042    Makefile.
2044    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2045    command called pgrep for grepping around the active processes.
2047    7. Added the beginnings of support for UTF-8 character strings.
2049    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2050    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2051    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2052    out for the ar command.)
2055  Version 3.2 12-May-00  Version 3.2 12-May-00
2056  ---------------------  ---------------------

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