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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.1 12-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
36        makevp_c.txt, makevp_l.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. (Test 2 will be tidied up later.)
116    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
117        segmentation fault instead of returning the appropriate error message.
119    15. In multiline mode when the newline sequence was set to "any", the pattern
120        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
121        This doesn't seem right; it now treats the CRLF combination as the line
122        ending, and so does not match in that case. It's only a pattern such as ^$
123        that would hit this one: something like ^ABC$ would have failed after \r
124        and then tried again after \r\n.
126    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
127        in an attempt to make files that differ only in their line terminators
128        compare equal. This works on Linux.
130    17. Under certain error circumstances pcregrep might try to free random memory
131        as it exited. This is now fixed, thanks to valgrind.
133    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
134        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
135        was because its rules for how to advance for /g after matching an empty
136        string at the end of a line did not allow for this case. They now check for
137        it specially.
139    20. pcretest is supposed to handle patterns and data of any length, by
140        extending its buffers when necessary. It was getting this wrong when the
141        buffer for a data line had to be extended.
143    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
144        CRLF as a newline sequence.
147    Version 7.0 19-Dec-06
148    ---------------------
150     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
151        moving to gcc 4.1.1.
153     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
154        sys/time.h, which is documented as needed for this function. It doesn't
155        seem to matter on Linux, but it showed up on some releases of OS X.
157     3. It seems that there are systems where bytes whose values are greater than
158        127 match isprint() in the "C" locale. The "C" locale should be the
159        default when a C program starts up. In most systems, only ASCII printing
160        characters match isprint(). This difference caused the output from pcretest
161        to vary, making some of the tests fail. I have changed pcretest so that:
163        (a) When it is outputting text in the compiled version of a pattern, bytes
164            other than 32-126 are always shown as hex escapes.
166        (b) When it is outputting text that is a matched part of a subject string,
167            it does the same, unless a different locale has been set for the match
168            (using the /L modifier). In this case, it uses isprint() to decide.
170     4. Fixed a major bug that caused incorrect computation of the amount of memory
171        required for a compiled pattern when options that changed within the
172        pattern affected the logic of the preliminary scan that determines the
173        length. The relevant options are -x, and -i in UTF-8 mode. The result was
174        that the computed length was too small. The symptoms of this bug were
175        either the PCRE error "internal error: code overflow" from pcre_compile(),
176        or a glibc crash with a message such as "pcretest: free(): invalid next
177        size (fast)". Examples of patterns that provoked this bug (shown in
178        pcretest format) are:
180          /(?-x: )/x
181          /(?x)(?-x: \s*#\s*)/
182          /((?i)[\x{c0}])/8
183          /(?i:[\x{c0}])/8
185        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
186        is now done differently.
188     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
189        wrapper classes; (b) implement a new function in the C++ scanner that is
190        more efficient than the old way of doing things because it avoids levels of
191        recursion in the regex matching; (c) add a paragraph to the documentation
192        for the FullMatch() function.
194     6. The escape sequence \n was being treated as whatever was defined as
195        "newline". Not only was this contrary to the documentation, which states
196        that \n is character 10 (hex 0A), but it also went horribly wrong when
197        "newline" was defined as CRLF. This has been fixed.
199     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
200        was being set to -1 for the "end of line" case (supposedly a value that no
201        character can have). Though this value is never used (the check for end of
202        line is "zero bytes in current character"), it caused compiler complaints.
203        I've changed it to 0xffffffff.
205     8. In pcre_version.c, the version string was being built by a sequence of
206        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
207        string (as it is for production releases) called a macro with an empty
208        argument. The C standard says the result of this is undefined. The gcc
209        compiler treats it as an empty string (which was what was wanted) but it is
210        reported that Visual C gives an error. The source has been hacked around to
211        avoid this problem.
213     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
214        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
215        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
216        of them did).
218    10. Originally, pcretest opened its input and output without "b"; then I was
219        told that "b" was needed in some environments, so it was added for release
220        5.0 to both the input and output. (It makes no difference on Unix-like
221        systems.) Later I was told that it is wrong for the input on Windows. I've
222        now abstracted the modes into two macros, to make it easier to fiddle with
223        them, and removed "b" from the input mode under Windows.
225    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
227    12. Added -help and --help to pcretest as an official way of being reminded
228        of the options.
230    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
231        and pcrecpp.cc because they annoy compilers at high warning levels.
233    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
235    15. Fixed an occurrence of == in configure.ac that should have been = (shell
236        scripts are not C programs :-) and which was not noticed because it works
237        on Linux.
239    16. pcretest is supposed to handle any length of pattern and data line (as one
240        line or as a continued sequence of lines) by extending its input buffer if
241        necessary. This feature was broken for very long pattern lines, leading to
242        a string of junk being passed to pcre_compile() if the pattern was longer
243        than about 50K.
245    17. I have done a major re-factoring of the way pcre_compile() computes the
246        amount of memory needed for a compiled pattern. Previously, there was code
247        that made a preliminary scan of the pattern in order to do this. That was
248        OK when PCRE was new, but as the facilities have expanded, it has become
249        harder and harder to keep it in step with the real compile phase, and there
250        have been a number of bugs (see for example, 4 above). I have now found a
251        cunning way of running the real compile function in a "fake" mode that
252        enables it to compute how much memory it would need, while actually only
253        ever using a few hundred bytes of working memory and without too many
254        tests of the mode. This should make future maintenance and development
255        easier. A side effect of this work is that the limit of 200 on the nesting
256        depth of parentheses has been removed (though this was never a serious
257        limitation, I suspect). However, there is a downside: pcre_compile() now
258        runs more slowly than before (30% or more, depending on the pattern). I
259        hope this isn't a big issue. There is no effect on runtime performance.
261    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
262        newline (only possible for the last line of a file) and it was a
263        pattern that set a locale (followed by /Lsomething), pcretest crashed.
265    19. Added additional timing features to pcretest. (1) The -tm option now times
266        matching only, not compiling. (2) Both -t and -tm can be followed, as a
267        separate command line item, by a number that specifies the number of
268        repeats to use when timing. The default is 50000; this gives better
269        precision, but takes uncomfortably long for very large patterns.
271    20. Extended pcre_study() to be more clever in cases where a branch of a
272        subpattern has no definite first character. For example, (a*|b*)[cd] would
273        previously give no result from pcre_study(). Now it recognizes that the
274        first character must be a, b, c, or d.
276    21. There was an incorrect error "recursive call could loop indefinitely" if
277        a subpattern (or the entire pattern) that was being tested for matching an
278        empty string contained only one non-empty item after a nested subpattern.
279        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
280        incorrectly, because the \d was being skipped in the check.
282    22. The pcretest program now has a new pattern option /B and a command line
283        option -b, which is equivalent to adding /B to every pattern. This causes
284        it to show the compiled bytecode, without the additional information that
285        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
286        is the same as /B/I).
288    23. A new optimization is now able automatically to treat some sequences such
289        as a*b as a*+b. More specifically, if something simple (such as a character
290        or a simple class like \d) has an unlimited quantifier, and is followed by
291        something that cannot possibly match the quantified thing, the quantifier
292        is automatically "possessified".
294    24. A recursive reference to a subpattern whose number was greater than 39
295        went wrong under certain circumstances in UTF-8 mode. This bug could also
296        have affected the operation of pcre_study().
298    25. Realized that a little bit of performance could be had by replacing
299        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
301    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
303    27. Possessive quantifiers such as a++ were previously implemented by turning
304        them into atomic groups such as ($>a+). Now they have their own opcodes,
305        which improves performance. This includes the automatically created ones
306        from 23 above.
308    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
309        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
310        the first matched character to be a colon. This applied both to named and
311        numbered groups.
313    29. The ucpinternal.h header file was missing its idempotency #ifdef.
315    30. I was sent a "project" file called libpcre.a.dev which I understand makes
316        building PCRE on Windows easier, so I have included it in the distribution.
318    31. There is now a check in pcretest against a ridiculously large number being
319        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
320        loop, the loop is abandoned.
322    32. Forward references to subpatterns in conditions such as (?(2)...) where
323        subpattern 2 is defined later cause pcre_compile() to search forwards in
324        the pattern for the relevant set of parentheses. This search went wrong
325        when there were unescaped parentheses in a character class, parentheses
326        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
328    33. "Subroutine" calls and backreferences were previously restricted to
329        referencing subpatterns earlier in the regex. This restriction has now
330        been removed.
332    34. Added a number of extra features that are going to be in Perl 5.10. On the
333        whole, these are just syntactic alternatives for features that PCRE had
334        previously implemented using the Python syntax or my own invention. The
335        other formats are all retained for compatibility.
337        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
338            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
339            also .NET compatible.
341        (b) A recursion or subroutine call to a named group can now be defined as
342            (?&name) as well as (?P>name).
344        (c) A backreference to a named group can now be defined as \k<name> or
345            \k'name' as well as (?P=name). The new forms, as well as being in Perl
346            5.10, are also .NET compatible.
348        (d) A conditional reference to a named group can now use the syntax
349            (?(<name>) or (?('name') as well as (?(name).
351        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
352            groups (named and numbered) that are never evaluated inline, but can be
353            called as "subroutines" from elsewhere. In effect, the DEFINE condition
354            is always false. There may be only one alternative in such a group.
356        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
357            as the simple (?(R). The condition is true only if the most recent
358            recursion is that of the given number or name. It does not search out
359            through the entire recursion stack.
361        (g) The escape \gN or \g{N} has been added, where N is a positive or
362            negative number, specifying an absolute or relative reference.
364    35. Tidied to get rid of some further signed/unsigned compiler warnings and
365        some "unreachable code" warnings.
367    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
368        things, this adds five new scripts.
370    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
371        There were also incompatibilities regarding the handling of \Q..\E inside
372        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
373        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
375    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
376        matches an empty string, and forcibly breaks the loop. There were bugs in
377        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
378        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
379        separate and independent bugs (that affected different cases) have been
380        fixed.
382    39. Refactored the code to abolish the use of different opcodes for small
383        capturing bracket numbers. This is a tidy that I avoided doing when I
384        removed the limit on the number of capturing brackets for 3.5 back in 2001.
385        The new approach is not only tidier, it makes it possible to reduce the
386        memory needed to fix the previous bug (38).
388    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
389        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
390        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
391        mode.
393    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
394        report.
396    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
397        copy construction and assignment in the C++ wrapper.
399    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
400        couple of bugs that could have given wrong results in the "--newline=crlf"
401        case.
403    44. Added a number of casts and did some reorganization of signed/unsigned int
404        variables following suggestions from Dair Grant. Also renamed the variable
405        "this" as "item" because it is a C++ keyword.
407    45. Arranged for dftables to add
409          #include "pcre_internal.h"
411        to pcre_chartables.c because without it, gcc 4.x may remove the array
412        definition from the final binary if PCRE is built into a static library and
413        dead code stripping is activated.
415    46. For an unanchored pattern, if a match attempt fails at the start of a
416        newline sequence, and the newline setting is CRLF or ANY, and the next two
417        characters are CRLF, advance by two characters instead of one.
420    Version 6.7 04-Jul-06
421    ---------------------
423     1. In order to handle tests when input lines are enormously long, pcretest has
424        been re-factored so that it automatically extends its buffers when
425        necessary. The code is crude, but this _is_ just a test program. The
426        default size has been increased from 32K to 50K.
428     2. The code in pcre_study() was using the value of the re argument before
429        testing it for NULL. (Of course, in any sensible call of the function, it
430        won't be NULL.)
432     3. The memmove() emulation function in pcre_internal.h, which is used on
433        systems that lack both memmove() and bcopy() - that is, hardly ever -
434        was missing a "static" storage class specifier.
436     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
437        containing an extended class (one that cannot be represented by a bitmap
438        because it contains high-valued characters or Unicode property items, e.g.
439        [\pZ]). Almost always one would set UTF-8 mode when processing such a
440        pattern, but PCRE should not loop if you do not (it no longer does).
441        [Detail: two cases were found: (a) a repeated subpattern containing an
442        extended class; (b) a recursive reference to a subpattern that followed a
443        previous extended class. It wasn't skipping over the extended class
444        correctly when UTF-8 mode was not set.]
446     5. A negated single-character class was not being recognized as fixed-length
447        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
448        compile error "lookbehind assertion is not fixed length".
450     6. The RunPerlTest auxiliary script was showing an unexpected difference
451        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
452        write a Perl script that can interpret lines of an input file either as
453        byte characters or as UTF-8, which is what "perltest" was being required to
454        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
455        can't do is switch easily at run time between having the "use utf8;" pragma
456        or not. In the end, I fudged it by using the RunPerlTest script to insert
457        "use utf8;" explicitly for the UTF-8 tests.
459     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
460        the end of the subject string, contrary to the documentation and to what
461        Perl does. This was true of both matching functions. Now it matches only at
462        the start of the subject and immediately after *internal* newlines.
464     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
465        a pointer to an int instead of a pointer to an unsigned long int. This
466        caused problems on 64-bit systems.
468     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
469        instance of the 'standard' template library not being so standard".
471    10. There was no check on the number of named subpatterns nor the maximum
472        length of a subpattern name. The product of these values is used to compute
473        the size of the memory block for a compiled pattern. By supplying a very
474        long subpattern name and a large number of named subpatterns, the size
475        computation could be caused to overflow. This is now prevented by limiting
476        the length of names to 32 characters, and the number of named subpatterns
477        to 10,000.
479    11. Subpatterns that are repeated with specific counts have to be replicated in
480        the compiled pattern. The size of memory for this was computed from the
481        length of the subpattern and the repeat count. The latter is limited to
482        65535, but there was no limit on the former, meaning that integer overflow
483        could in principle occur. The compiled length of a repeated subpattern is
484        now limited to 30,000 bytes in order to prevent this.
486    12. Added the optional facility to have named substrings with the same name.
488    13. Added the ability to use a named substring as a condition, using the
489        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
490        are numbers (not recommended). Forward references are permitted.
492    14. Added forward references in named backreferences (if you see what I mean).
494    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
495        pattern could run off the end of the subject. For example, the pattern
496        "(?s)(.{1,5})"8 did this with the subject "ab".
498    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
499        PCRE_CASELESS was set when matching characters that were quantified with ?
500        or *.
502    17. A character class other than a single negated character that had a minimum
503        but no maximum quantifier - for example [ab]{6,} - was not handled
504        correctly by pce_dfa_exec(). It would match only one character.
506    18. A valid (though odd) pattern that looked like a POSIX character
507        class but used an invalid character after [ (for example [[,abc,]]) caused
508        pcre_compile() to give the error "Failed: internal error: code overflow" or
509        in some cases to crash with a glibc free() error. This could even happen if
510        the pattern terminated after [[ but there just happened to be a sequence of
511        letters, a binary zero, and a closing ] in the memory that followed.
513    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
514        over the years. Originally (before any Unicode support), just the bottom 8
515        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
516        output from "man perlunicode" includes this:
518          The regular expression compiler produces polymorphic opcodes.  That
519          is, the pattern adapts to the data and automatically switches to
520          the Unicode character scheme when presented with Unicode data--or
521          instead uses a traditional byte scheme when presented with byte
522          data.
524        Sadly, a wide octal escape does not cause a switch, and in a string with
525        no other multibyte characters, these octal escapes are treated as before.
526        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
527        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
528        Unicode string.
530        I have not perpetrated such confusion in PCRE. Up till now, it took just
531        the bottom 8 bits, as in old Perl. I have now made octal escapes with
532        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
533        translate to the appropriate multibyte character.
535    29. Applied some refactoring to reduce the number of warnings from Microsoft
536        and Borland compilers. This has included removing the fudge introduced
537        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
538        a warning about an unused variable.
540    21. PCRE has not included VT (character 0x0b) in the set of whitespace
541        characters since release 4.0, because Perl (from release 5.004) does not.
542        [Or at least, is documented not to: some releases seem to be in conflict
543        with the documentation.] However, when a pattern was studied with
544        pcre_study() and all its branches started with \s, PCRE still included VT
545        as a possible starting character. Of course, this did no harm; it just
546        caused an unnecessary match attempt.
548    22. Removed a now-redundant internal flag bit that recorded the fact that case
549        dependency changed within the pattern. This was once needed for "required
550        byte" processing, but is no longer used. This recovers a now-scarce options
551        bit. Also moved the least significant internal flag bit to the most-
552        significant bit of the word, which was not previously used (hangover from
553        the days when it was an int rather than a uint) to free up another bit for
554        the future.
556    23. Added support for CRLF line endings as well as CR and LF. As well as the
557        default being selectable at build time, it can now be changed at runtime
558        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
559        specify that it is scanning data with non-default line endings.
561    24. Changed the definition of CXXLINK to make it agree with the definition of
562        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
564    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
565        recursions. This makes a big different to stack usage for some patterns.
567    26. If a subpattern containing a named recursion or subroutine reference such
568        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
569        the space required for the compiled pattern went wrong and gave too small a
570        value. Depending on the environment, this could lead to "Failed: internal
571        error: code overflow at offset 49" or "glibc detected double free or
572        corruption" errors.
574    27. Applied patches from Google (a) to support the new newline modes and (b) to
575        advance over multibyte UTF-8 characters in GlobalReplace.
577    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
578        difference for some implementation of PCRE in some Windows version.
580    29. Added some extra testing facilities to pcretest:
582        \q<number>   in a data line sets the "match limit" value
583        \Q<number>   in a data line sets the "match recursion limt" value
584        -S <number>  sets the stack size, where <number> is in megabytes
586        The -S option isn't available for Windows.
589    Version 6.6 06-Feb-06
590    ---------------------
592     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
593        in pcreposix.h. I have copied the definition from pcre.h.
595     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
596        because pcre.h is no longer a built file.
598     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
599        not normally included in the compiled code.
602    Version 6.5 01-Feb-06
603    ---------------------
605     1. When using the partial match feature with pcre_dfa_exec(), it was not
606        anchoring the second and subsequent partial matches at the new starting
607        point. This could lead to incorrect results. For example, with the pattern
608        /1234/, partially matching against "123" and then "a4" gave a match.
610     2. Changes to pcregrep:
612        (a) All non-match returns from pcre_exec() were being treated as failures
613            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
614            error message is output. Some extra information is given for the
615            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
616            probably the only errors that are likely to be caused by users (by
617            specifying a regex that has nested indefinite repeats, for instance).
618            If there are more than 20 of these errors, pcregrep is abandoned.
620        (b) A binary zero was treated as data while matching, but terminated the
621            output line if it was written out. This has been fixed: binary zeroes
622            are now no different to any other data bytes.
624        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
625            used to set a locale for matching. The --locale=xxxx long option has
626            been added (no short equivalent) to specify a locale explicitly on the
627            pcregrep command, overriding the environment variables.
629        (d) When -B was used with -n, some line numbers in the output were one less
630            than they should have been.
632        (e) Added the -o (--only-matching) option.
634        (f) If -A or -C was used with -c (count only), some lines of context were
635            accidentally printed for the final match.
637        (g) Added the -H (--with-filename) option.
639        (h) The combination of options -rh failed to suppress file names for files
640            that were found from directory arguments.
642        (i) Added the -D (--devices) and -d (--directories) options.
644        (j) Added the -F (--fixed-strings) option.
646        (k) Allow "-" to be used as a file name for -f as well as for a data file.
648        (l) Added the --colo(u)r option.
650        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
651            is not present by default.
653     3. A nasty bug was discovered in the handling of recursive patterns, that is,
654        items such as (?R) or (?1), when the recursion could match a number of
655        alternatives. If it matched one of the alternatives, but subsequently,
656        outside the recursion, there was a failure, the code tried to back up into
657        the recursion. However, because of the way PCRE is implemented, this is not
658        possible, and the result was an incorrect result from the match.
660        In order to prevent this happening, the specification of recursion has
661        been changed so that all such subpatterns are automatically treated as
662        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
664     4. I had overlooked the fact that, in some locales, there are characters for
665        which isalpha() is true but neither isupper() nor islower() are true. In
666        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
667        and ordfeminine) are like this. This affected the treatment of \w and \W
668        when they appeared in character classes, but not when they appeared outside
669        a character class. The bit map for "word" characters is now created
670        separately from the results of isalnum() instead of just taking it from the
671        upper, lower, and digit maps. (Plus the underscore character, of course.)
673     5. The above bug also affected the handling of POSIX character classes such as
674        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
675        permanent tables. Instead, the bit maps for such a class were previously
676        created as the appropriate unions of the upper, lower, and digit bitmaps.
677        Now they are created by subtraction from the [[:word:]] class, which has
678        its own bitmap.
680     6. The [[:blank:]] character class matches horizontal, but not vertical space.
681        It is created by subtracting the vertical space characters (\x09, \x0a,
682        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
683        subtraction was done in the overall bitmap for a character class, meaning
684        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
685        be recognized. This bug has been fixed.
687     7. Patches from the folks at Google:
689          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
690          real life, but is still worth protecting against".
692          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
693          regular expressions".
695          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
696          have it.
698          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
699          "configure" and the latter not, in order to fix a problem somebody had
700          with compiling the Arg class on HP-UX.
702          (e) Improve the error-handling of the C++ wrapper a little bit.
704          (f) New tests for checking recursion limiting.
706     8. The pcre_memmove() function, which is used only if the environment does not
707        have a standard memmove() function (and is therefore rarely compiled),
708        contained two bugs: (a) use of int instead of size_t, and (b) it was not
709        returning a result (though PCRE never actually uses the result).
711     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
712        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
713        returned instead of calling malloc() with an overflowing number that would
714        most likely cause subsequent chaos.
716    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
718    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
719        with this option is matched, the nmatch and pmatch options of regexec() are
720        ignored.
722    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
723        provided in case anyone wants to the the POSIX interface with UTF-8
724        strings.
726    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
727        C++ linking (needed for some HP-UX environments).
729    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
730        (unused parameter) and in the pcre_printint() function (omitted "default"
731        switch label when the default is to do nothing).
733    15. Added some code to make it possible, when PCRE is compiled as a C++
734        library, to replace subject pointers for pcre_exec() with a smart pointer
735        class, thus making it possible to process discontinuous strings.
737    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
738        much the same function. They were added by different people who were trying
739        to make PCRE easy to compile on non-Unix systems. It has been suggested
740        that PCRE_EXPORT be abolished now that there is more automatic apparatus
741        for compiling on Windows systems. I have therefore replaced it with
742        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
743        defaults to "extern" for C or "extern C" for C++, which works fine on
744        Unix-like systems. It is now possible to override the value of PCRE_DATA_
745        SCOPE with something explicit in config.h. In addition:
747        (a) pcreposix.h still had just "extern" instead of either of these macros;
748            I have replaced it with PCRE_DATA_SCOPE.
750        (b) Functions such as _pcre_xclass(), which are internal to the library,
751            but external in the C sense, all had PCRE_EXPORT in their definitions.
752            This is apparently wrong for the Windows case, so I have removed it.
753            (It makes no difference on Unix-like systems.)
755    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
756        of recursive calls to match(). This is different to MATCH_LIMIT because
757        that limits the total number of calls to match(), not all of which increase
758        the depth of recursion. Limiting the recursion depth limits the amount of
759        stack (or heap if NO_RECURSE is set) that is used. The default can be set
760        when PCRE is compiled, and changed at run time. A patch from Google adds
761        this functionality to the C++ interface.
763    18. Changes to the handling of Unicode character properties:
765        (a) Updated the table to Unicode 4.1.0.
767        (b) Recognize characters that are not in the table as "Cn" (undefined).
769        (c) I revised the way the table is implemented to a much improved format
770            which includes recognition of ranges. It now supports the ranges that
771            are defined in UnicodeData.txt, and it also amalgamates other
772            characters into ranges. This has reduced the number of entries in the
773            table from around 16,000 to around 3,000, thus reducing its size
774            considerably. I realized I did not need to use a tree structure after
775            all - a binary chop search is just as efficient. Having reduced the
776            number of entries, I extended their size from 6 bytes to 8 bytes to
777            allow for more data.
779        (d) Added support for Unicode script names via properties such as \p{Han}.
781    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
782        matching that character.
784    20. When matching a repeated Unicode property with a minimum greater than zero,
785        (for example \pL{2,}), PCRE could look past the end of the subject if it
786        reached it while seeking the minimum number of characters. This could
787        happen only if some of the characters were more than one byte long, because
788        there is a check for at least the minimum number of bytes.
790    21. Refactored the implementation of \p and \P so as to be more general, to
791        allow for more different types of property in future. This has changed the
792        compiled form incompatibly. Anybody with saved compiled patterns that use
793        \p or \P will have to recompile them.
795    22. Added "Any" and "L&" to the supported property types.
797    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
798        but give a compile time error if the value is greater than 0xff.
800    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
801        accidentally not being installed or uninstalled.
803    25. The pcre.h file was built from pcre.h.in, but the only changes that were
804        made were to insert the current release number. This seemed silly, because
805        it made things harder for people building PCRE on systems that don't run
806        "configure". I have turned pcre.h into a distributed file, no longer built
807        by "configure", with the version identification directly included. There is
808        no longer a pcre.h.in file.
810        However, this change necessitated a change to the pcre-config script as
811        well. It is built from pcre-config.in, and one of the substitutions was the
812        release number. I have updated configure.ac so that ./configure now finds
813        the release number by grepping pcre.h.
815    26. Added the ability to run the tests under valgrind.
818    Version 6.4 05-Sep-05
819    ---------------------
821     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
822        "--" to be printed when multiple files were scanned, even when none of the
823        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
824        consider it to be a bug, and have restored the previous behaviour.
826     2. A couple of code tidies to get rid of compiler warnings.
828     3. The pcretest program used to cheat by referring to symbols in the library
829        whose names begin with _pcre_. These are internal symbols that are not
830        really supposed to be visible externally, and in some environments it is
831        possible to suppress them. The cheating is now confined to including
832        certain files from the library's source, which is a bit cleaner.
834     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
835        file's purpose clearer.
837     5. Reorganized pcre_ucp_findchar().
840    Version 6.3 15-Aug-05
841    ---------------------
843     1. The file libpcre.pc.in did not have general read permission in the tarball.
845     2. There were some problems when building without C++ support:
847        (a) If C++ support was not built, "make install" and "make test" still
848            tried to test it.
850        (b) There were problems when the value of CXX was explicitly set. Some
851            changes have been made to try to fix these, and ...
853        (c) --disable-cpp can now be used to explicitly disable C++ support.
855        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
856            backslash in a target when C++ was disabled. This confuses some
857            versions of "make", apparently. Using an intermediate variable solves
858            this. (Same for CPP_LOBJ.)
860     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
861        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
862        necessary on certain architectures.
864     4. Added a setting of -export-symbols-regex to the link command to remove
865        those symbols that are exported in the C sense, but actually are local
866        within the library, and not documented. Their names all begin with
867        "_pcre_". This is not a perfect job, because (a) we have to except some
868        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
869        available (and never for static libraries). I have made a note to try to
870        find a way round (a) in the future.
873    Version 6.2 01-Aug-05
874    ---------------------
876     1. There was no test for integer overflow of quantifier values. A construction
877        such as {1111111111111111} would give undefined results. What is worse, if
878        a minimum quantifier for a parenthesized subpattern overflowed and became
879        negative, the calculation of the memory size went wrong. This could have
880        led to memory overwriting.
882     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
884     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
885        operating environments where this matters.
887     4. Applied Giuseppe Maxia's patch to add additional features for controlling
888        PCRE options from within the C++ wrapper.
890     5. Named capturing subpatterns were not being correctly counted when a pattern
891        was compiled. This caused two problems: (a) If there were more than 100
892        such subpatterns, the calculation of the memory needed for the whole
893        compiled pattern went wrong, leading to an overflow error. (b) Numerical
894        back references of the form \12, where the number was greater than 9, were
895        not recognized as back references, even though there were sufficient
896        previous subpatterns.
898     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
899        versions of gcc, e.g. 2.95.4.
902    Version 6.1 21-Jun-05
903    ---------------------
905     1. There was one reference to the variable "posix" in pcretest.c that was not
906        surrounded by "#if !defined NOPOSIX".
908     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
909        the cross-check on the old pcre_info() function, for the benefit of the
910        cut-down version of PCRE that is currently imported into Exim.
912     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
913        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
914        patterns that start (?i) but I don't think that matters. The use of (?i) is
915        just an example; this all applies to the other options as well.
917     4. Since libtool seems to echo the compile commands it is issuing, the output
918        from "make" can be reduced a bit by putting "@" in front of each libtool
919        compile command.
921     5. Patch from the folks at Google for configure.in to be a bit more thorough
922        in checking for a suitable C++ installation before trying to compile the
923        C++ stuff. This should fix a reported problem when a compiler was present,
924        but no suitable headers.
926     6. The man pages all had just "PCRE" as their title. I have changed them to
927        be the relevant file name. I have also arranged that these names are
928        retained in the file doc/pcre.txt, which is a concatenation in text format
929        of all the man pages except the little individual ones for each function.
931     7. The NON-UNIX-USE file had not been updated for the different set of source
932        files that come with release 6. I also added a few comments about the C++
933        wrapper.
936    Version 6.0 07-Jun-05
937    ---------------------
939     1. Some minor internal re-organization to help with my DFA experiments.
941     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
942        didn't matter for the library itself when fully configured, but did matter
943        when compiling without UCP support, or within Exim, where the ucp files are
944        not imported.
946     3. Refactoring of the library code to split up the various functions into
947        different source modules. The addition of the new DFA matching code (see
948        below) to a single monolithic source would have made it really too
949        unwieldy, quite apart from causing all the code to be include in a
950        statically linked application, when only some functions are used. This is
951        relevant even without the DFA addition now that patterns can be compiled in
952        one application and matched in another.
954        The downside of splitting up is that there have to be some external
955        functions and data tables that are used internally in different modules of
956        the library but which are not part of the API. These have all had their
957        names changed to start with "_pcre_" so that they are unlikely to clash
958        with other external names.
960     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
961        a different (DFA) algorithm. Although it is slower than the original
962        function, it does have some advantages for certain types of matching
963        problem.
965     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
966        including restarting after a partial match.
968     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
969        defined when compiling for Windows was sent to me. I have put it into the
970        code, though I have no means of testing or verifying it.
972     7. Added the pcre_refcount() auxiliary function.
974     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
975        match before or at the first newline in the subject string. In pcretest,
976        the /f option on a pattern can be used to set this.
978     9. A repeated \w when used in UTF-8 mode with characters greater than 256
979        would behave wrongly. This has been present in PCRE since release 4.0.
981    10. A number of changes to the pcregrep command:
983        (a) Refactored how -x works; insert ^(...)$ instead of setting
984            PCRE_ANCHORED and checking the length, in preparation for adding
985            something similar for -w.
987        (b) Added the -w (match as a word) option.
989        (c) Refactored the way lines are read and buffered so as to have more
990            than one at a time available.
992        (d) Implemented a pcregrep test script.
994        (e) Added the -M (multiline match) option. This allows patterns to match
995            over several lines of the subject. The buffering ensures that at least
996            8K, or the rest of the document (whichever is the shorter) is available
997            for matching (and similarly the previous 8K for lookbehind assertions).
999        (f) Changed the --help output so that it now says
1001              -w, --word-regex(p)
1003            instead of two lines, one with "regex" and the other with "regexp"
1004            because that confused at least one person since the short forms are the
1005            same. (This required a bit of code, as the output is generated
1006            automatically from a table. It wasn't just a text change.)
1008        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1009            option but starts with a hyphen. Could be a pattern or a path name
1010            starting with a hyphen, for instance.
1012        (h) "-" can be given as a file name to represent stdin.
1014        (i) When file names are being printed, "(standard input)" is used for
1015            the standard input, for compatibility with GNU grep. Previously
1016            "<stdin>" was used.
1018        (j) The option --label=xxx can be used to supply a name to be used for
1019            stdin when file names are being printed. There is no short form.
1021        (k) Re-factored the options decoding logic because we are going to add
1022            two more options that take data. Such options can now be given in four
1023            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1025        (l) Added the -A, -B, and -C options for requesting that lines of context
1026            around matches be printed.
1028        (m) Added the -L option to print the names of files that do not contain
1029            any matching lines, that is, the complement of -l.
1031        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1032            continue to scan other files.
1034        (o) The -s option was incorrectly implemented. For compatibility with other
1035            greps, it now suppresses the error message for a non-existent or non-
1036            accessible file (but not the return code). There is a new option called
1037            -q that suppresses the output of matching lines, which was what -s was
1038            previously doing.
1040        (p) Added --include and --exclude options to specify files for inclusion
1041            and exclusion when recursing.
1043    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1044        Hopefully, it now does.
1046    12. Missing cast in pcre_study().
1048    13. Added an "uninstall" target to the makefile.
1050    14. Replaced "extern" in the function prototypes in Makefile.in with
1051        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1052        world, but is set differently for Windows.
1054    15. Added a second compiling function called pcre_compile2(). The only
1055        difference is that it has an extra argument, which is a pointer to an
1056        integer error code. When there is a compile-time failure, this is set
1057        non-zero, in addition to the error test pointer being set to point to an
1058        error message. The new argument may be NULL if no error number is required
1059        (but then you may as well call pcre_compile(), which is now just a
1060        wrapper). This facility is provided because some applications need a
1061        numeric error indication, but it has also enabled me to tidy up the way
1062        compile-time errors are handled in the POSIX wrapper.
1064    16. Added VPATH=.libs to the makefile; this should help when building with one
1065        prefix path and installing with another. (Or so I'm told by someone who
1066        knows more about this stuff than I do.)
1068    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1069        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1070        match everything, including newlines. This is not POSIX-compatible, but
1071        somebody wanted the feature. From pcretest it can be activated by using
1072        both the P and the s flags.
1074    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1076    19. libpcre.pc was being incorrectly installed as executable.
1078    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1079        it now also looks for '\r' so that it will work unmodified on Windows.
1081    21. Added Google's contributed C++ wrapper to the distribution.
1083    22. Added some untidy missing memory free() calls in pcretest, to keep
1084        Electric Fence happy when testing.
1088    Version 5.0 13-Sep-04
1089    ---------------------
1091     1. Internal change: literal characters are no longer packed up into items
1092        containing multiple characters in a single byte-string. Each character
1093        is now matched using a separate opcode. However, there may be more than one
1094        byte in the character in UTF-8 mode.
1096     2. The pcre_callout_block structure has two new fields: pattern_position and
1097        next_item_length. These contain the offset in the pattern to the next match
1098        item, and its length, respectively.
1100     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1101        insertion of callouts before each pattern item. Added the /C option to
1102        pcretest to make use of this.
1104     4. On the advice of a Windows user, the lines
1106          #if defined(_WIN32) || defined(WIN32)
1107          _setmode( _fileno( stdout ), 0x8000 );
1108          #endif  /* defined(_WIN32) || defined(WIN32) */
1110        have been added to the source of pcretest. This apparently does useful
1111        magic in relation to line terminators.
1113     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1114        for the benefit of those environments where the "b" makes a difference.
1116     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1117        to know about it. I have put a hack into configure.in that adds in code
1118        to set GCC=yes if CC=icc. This seems to end up at a point in the
1119        generated configure script that is early enough to affect the setting of
1120        compiler options, which is what is needed, but I have no means of testing
1121        whether it really works. (The user who reported this had patched the
1122        generated configure script, which of course I cannot do.)
1124        LATER: After change 22 below (new libtool files), the configure script
1125        seems to know about icc (and also ecc). Therefore, I have commented out
1126        this hack in configure.in.
1128     7. Added support for pkg-config (2 patches were sent in).
1130     8. Negated POSIX character classes that used a combination of internal tables
1131        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1132        [[:^ascii]]. Typically, they would match almost any characters. The other
1133        POSIX classes were not broken in this way.
1135     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1136        to find the match, as PCRE was deluded into thinking that the match had to
1137        start at the start point or following a newline. The same bug applied to
1138        patterns with negative forward assertions or any backward assertions
1139        preceding ".*" at the start, unless the pattern required a fixed first
1140        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1142    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1143        starting at the last subject character, bytes beyond the end of the subject
1144        string were read.
1146    11. Renamed the variable "class" as "classbits" to make life easier for C++
1147        users. (Previously there was a macro definition, but it apparently wasn't
1148        enough.)
1150    12. Added the new field "tables" to the extra data so that tables can be passed
1151        in at exec time, or the internal tables can be re-selected. This allows
1152        a compiled regex to be saved and re-used at a later time by a different
1153        program that might have everything at different addresses.
1155    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1156        -R library as well as a -L library.
1158    14. The debugging options of pcretest (-d on the command line or D on a
1159        pattern) showed incorrect output for anything following an extended class
1160        that contained multibyte characters and which was followed by a quantifier.
1162    15. Added optional support for general category Unicode character properties
1163        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1164        support. It adds about 90K to the size of the library. The meanings of the
1165        inbuilt class escapes such as \d and \s have NOT been changed.
1167    16. Updated pcredemo.c to include calls to free() to release the memory for the
1168        compiled pattern.
1170    17. The generated file chartables.c was being created in the source directory
1171        instead of in the building directory. This caused the build to fail if the
1172        source directory was different from the building directory, and was
1173        read-only.
1175    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1176        file. No doubt somebody will tell me if they don't make sense... Also added
1177        Dan Mooney's comments about building on OpenVMS.
1179    19. Added support for partial matching via the PCRE_PARTIAL option for
1180        pcre_exec() and the \P data escape in pcretest.
1182    20. Extended pcretest with 3 new pattern features:
1184        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1185              write the compiled pattern to the file whose name is "rest-of-line".
1186              This is a straight binary dump of the data, with the saved pointer to
1187              the character tables forced to be NULL. The study data, if any, is
1188              written too. After writing, pcretest reads a new pattern.
1190        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1191              compiled pattern from the given file. There must not be any
1192              occurrences of "<" in the file name (pretty unlikely); if there are,
1193              pcretest will instead treat the initial "<" as a pattern delimiter.
1194              After reading in the pattern, pcretest goes on to read data lines as
1195              usual.
1197        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1198              and 16-bit fields in a compiled pattern, to simulate a pattern that
1199              was compiled on a host of opposite endianness.
1201    21. The pcre-exec() function can now cope with patterns that were compiled on
1202        hosts of opposite endianness, with this restriction:
1204          As for any compiled expression that is saved and used later, the tables
1205          pointer field cannot be preserved; the extra_data field in the arguments
1206          to pcre_exec() should be used to pass in a tables address if a value
1207          other than the default internal tables were used at compile time.
1209    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1210        now diagnosed as an error. Previously, most of the time, a negative number
1211        would have been treated as zero, but if in addition "ovector" was passed as
1212        NULL, a crash could occur.
1214    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1215        new versions from the libtool 1.5 distribution (the last one is a copy of
1216        a file called libtool.m4). This seems to have fixed the need to patch
1217        "configure" to support Darwin 1.3 (which I used to do). However, I still
1218        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1219        workstation).
1221    24. Changed the PCRE licence to be the more standard "BSD" licence.
1224    Version 4.5 01-Dec-03
1225    ---------------------
1227     1. There has been some re-arrangement of the code for the match() function so
1228        that it can be compiled in a version that does not call itself recursively.
1229        Instead, it keeps those local variables that need separate instances for
1230        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1231        needs to "recurse". Keeping track of where control must go is done by means
1232        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1233        hide most of the details from the main code, and operates only if
1234        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1235        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1236        operating.
1238        To make it easier for callers to provide specially tailored get/free
1239        functions for this usage, two new functions, pcre_stack_malloc, and
1240        pcre_stack_free, are used. They are always called in strict stacking order,
1241        and the size of block requested is always the same.
1243        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1244        PCRE has been compiled to use the stack or the heap for recursion. The
1245        -C option of pcretest uses this to show which version is compiled.
1247        A new data escape \S, is added to pcretest; it causes the amounts of store
1248        obtained and freed by both kinds of malloc/free at match time to be added
1249        to the output.
1251     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1252        what's available on my current Linux desktop machine.
1254     3. When matching a UTF-8 string, the test for a valid string at the start has
1255        been extended. If start_offset is not zero, PCRE now checks that it points
1256        to a byte that is the start of a UTF-8 character. If not, it returns
1257        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1258        this is necessary because there may be backward assertions in the pattern.
1259        When matching the same subject several times, it may save resources to use
1260        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1262     4. The code for checking the validity of UTF-8 strings has been tightened so
1263        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1264        containing "overlong sequences".
1266     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1267        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1268        should have been "&", but it just so happened that all the cases this let
1269        through by mistake were picked up later in the function.
1271     6. I had used a variable called "isblank" - this is a C99 function, causing
1272        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1274     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1275        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1276        so the version is shown; (c) stop "make test" echoing "./RunTest".
1278     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1280     9. The prototype for memmove() for systems that don't have it was using
1281        size_t, but the inclusion of the header that defines size_t was later. I've
1282        moved the #includes for the C headers earlier to avoid this.
1284    10. Added some adjustments to the code to make it easier to compiler on certain
1285        special systems:
1287          (a) Some "const" qualifiers were missing.
1288          (b) Added the macro EXPORT before all exported functions; by default this
1289              is defined to be empty.
1290          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1291              that it reads its output file name as an argument instead of writing
1292              to the standard output and assuming this can be redirected.
1294    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1295        class containing characters with values greater than 255, PCRE compilation
1296        went into a loop.
1298    12. A recursive reference to a subpattern that was within another subpattern
1299        that had a minimum quantifier of zero caused PCRE to crash. For example,
1300        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1301        recursion. If the recursively-called subpattern itself had a zero repeat,
1302        that was OK.
1304    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1305        buffer into which it was copied (for escape processing) was still set at
1306        1024, so long lines caused crashes.
1308    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1309        "internal error: code overflow...". This applied to any character class
1310        that was followed by a possessive quantifier.
1312    15. Modified the Makefile to add libpcre.la as a prerequisite for
1313        libpcreposix.la because I was told this is needed for a parallel build to
1314        work.
1316    16. If a pattern that contained .* following optional items at the start was
1317        studied, the wrong optimizing data was generated, leading to matching
1318        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1319        matching string must start with a or b or c. The correct conclusion for
1320        this pattern is that a match can start with any character.
1323    Version 4.4 13-Aug-03
1324    ---------------------
1326     1. In UTF-8 mode, a character class containing characters with values between
1327        127 and 255 was not handled correctly if the compiled pattern was studied.
1328        In fixing this, I have also improved the studying algorithm for such
1329        classes (slightly).
1331     2. Three internal functions had redundant arguments passed to them. Removal
1332        might give a very teeny performance improvement.
1334     3. Documentation bug: the value of the capture_top field in a callout is *one
1335        more than* the number of the hightest numbered captured substring.
1337     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1338        in incorrectly linking with a previously installed version. They now link
1339        explicitly with libpcre.la.
1341     5. configure.in no longer needs to recognize Cygwin specially.
1343     6. A problem in pcre.in for Windows platforms is fixed.
1345     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1346        pcretest, it used to include the size of the study block as part of its
1347        output. Unfortunately, the structure contains a field that has a different
1348        size on different hardware architectures. This meant that the tests that
1349        showed this size failed. As the block is currently always of a fixed size,
1350        this information isn't actually particularly useful in pcretest output, so
1351        I have just removed it.
1353     8. Three pre-processor statements accidentally did not start in column 1.
1354        Sadly, there are *still* compilers around that complain, even though
1355        standard C has not required this for well over a decade. Sigh.
1357     9. In pcretest, the code for checking callouts passed small integers in the
1358        callout_data field, which is a void * field. However, some picky compilers
1359        complained about the casts involved for this on 64-bit systems. Now
1360        pcretest passes the address of the small integer instead, which should get
1361        rid of the warnings.
1363    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1364        both compile and run time, and gives an error if an invalid UTF-8 sequence
1365        is found. There is a option for disabling this check in cases where the
1366        string is known to be correct and/or the maximum performance is wanted.
1368    11. In response to a bug report, I changed one line in Makefile.in from
1370            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1371        to
1372            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1374        to look similar to other lines, but I have no way of telling whether this
1375        is the right thing to do, as I do not use Windows. No doubt I'll get told
1376        if it's wrong...
1379    Version 4.3 21-May-03
1380    ---------------------
1382    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1383       Makefile.
1385    2. Some refactoring to improve the quality of the code:
1387       (i)   The utf8_table... variables are now declared "const".
1389       (ii)  The code for \cx, which used the "case flipping" table to upper case
1390             lower case letters, now just substracts 32. This is ASCII-specific,
1391             but the whole concept of \cx is ASCII-specific, so it seems
1392             reasonable.
1394       (iii) PCRE was using its character types table to recognize decimal and
1395             hexadecimal digits in the pattern. This is silly, because it handles
1396             only 0-9, a-f, and A-F, but the character types table is locale-
1397             specific, which means strange things might happen. A private
1398             table is now used for this - though it costs 256 bytes, a table is
1399             much faster than multiple explicit tests. Of course, the standard
1400             character types table is still used for matching digits in subject
1401             strings against \d.
1403       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1404             ending in _t are). So I've renamed it as ESC_tee.
1406    3. The first argument for regexec() in the POSIX wrapper should have been
1407       defined as "const".
1409    4. Changed pcretest to use malloc() for its buffers so that they can be
1410       Electric Fenced for debugging.
1412    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1413       to read one or more bytes before the start of the subject string. Often this
1414       had no effect on PCRE's behaviour, but in some circumstances it could
1415       provoke a segmentation fault.
1417    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1418       to try to read one or more bytes before the start of the subject string.
1420    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1421       UTF-8 support could misbehave in various ways if the subject string
1422       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1423       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1424       back over UTF-8 characters.)
1427    Version 4.2 14-Apr-03
1428    ---------------------
1430    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1432    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1433         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1434         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1435         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1436         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1437           and BUILD_EXEEXT
1438         Note: automatic setting of the BUILD variables is not yet working
1439         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1440           compile-time but not at link-time
1441         [LINK]: use for linking executables only
1442         make different versions for Windows and non-Windows
1443         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1444           libraries
1445         [LINK_FOR_BUILD]: new variable
1446         [OBJEXT]: use throughout
1447         [EXEEXT]: use throughout
1448         <winshared>: new target
1449         <wininstall>: new target
1450         <dftables.o>: use native compiler
1451         <dftables>: use native linker
1452         <install>: handle Windows platform correctly
1453         <clean>: ditto
1454         <check>: ditto
1455         copy DLL to top builddir before testing
1457       As part of these changes, -no-undefined was removed again. This was reported
1458       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1459       in any case.
1461    3. Some tidies to get rid of compiler warnings:
1463       . In the match_data structure, match_limit was an unsigned long int, whereas
1464         match_call_count was an int. I've made them both unsigned long ints.
1466       . In pcretest the fact that a const uschar * doesn't automatically cast to
1467         a void * provoked a warning.
1469       . Turning on some more compiler warnings threw up some "shadow" variables
1470         and a few more missing casts.
1472    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1473       option, a class that contained a single character with a value between 128
1474       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1476    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1477       option, a class that contained several characters, but with at least one
1478       whose value was between 128 and 255 caused PCRE to crash.
1481    Version 4.1 12-Mar-03
1482    ---------------------
1484    1. Compiling with gcc -pedantic found a couple of places where casts were
1485    needed, and a string in dftables.c that was longer than standard compilers are
1486    required to support.
1488    2. Compiling with Sun's compiler found a few more places where the code could
1489    be tidied up in order to avoid warnings.
1491    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1492    first of these names is deprecated in the latest Autoconf in favour of the name
1493    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1494    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1495    analogy I have changed it to CFLAGS_FOR_BUILD.
1497    4. Added -no-undefined to the linking command in the Makefile, because this is
1498    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1499    linking step for the pcreposix library.
1501    5. PCRE was failing to diagnose the case of two named groups with the same
1502    name.
1504    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1505    literal character that is needed in the subject for a match, and scans along to
1506    ensure that it is present before embarking on the full matching process. This
1507    saves time in cases of nested unlimited repeats that are never going to match.
1508    Problem: the scan can take a lot of time if the subject is very long (e.g.
1509    megabytes), thus penalizing straightforward matches. It is now done only if the
1510    amount of subject to be scanned is less than 1000 bytes.
1512    7. A lesser problem with the same optimization is that it was recording the
1513    first character of an anchored pattern as "needed", thus provoking a search
1514    right along the subject, even when the first match of the pattern was going to
1515    fail. The "needed" character is now not set for anchored patterns, unless it
1516    follows something in the pattern that is of non-fixed length. Thus, it still
1517    fulfils its original purpose of finding quick non-matches in cases of nested
1518    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1521    Version 4.0 17-Feb-03
1522    ---------------------
1524    1. If a comment in an extended regex that started immediately after a meta-item
1525    extended to the end of string, PCRE compiled incorrect data. This could lead to
1526    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1528    2. Moved to autoconf 2.53 and libtool 1.4.2.
1530    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1531    the special perltest8 script is no longer needed - all the tests can be run
1532    from a single perltest script.
1534    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1535    by \s. It has now been removed in PCRE. This means it isn't recognized as
1536    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1537    class [:space:] *does* include VT, thereby creating a mess.
1539    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1540    space and tab.
1542    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1543    its new features into the main test script, reducing the number of scripts.
1545    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1546    were backward compatible, and made the (?i) apply to the whole pattern, as if
1547    /i were given. Now it behaves more logically, and applies the option setting
1548    only to what follows. PCRE has been changed to follow suit. However, if it
1549    finds options settings right at the start of the pattern, it extracts them into
1550    the global options, as before. Thus, they show up in the info data.
1552    8. Added support for the \Q...\E escape sequence. Characters in between are
1553    treated as literals. This is slightly different from Perl in that $ and @ are
1554    also handled as literals inside the quotes. In Perl, they will cause variable
1555    interpolation. Note the following examples:
1557        Pattern            PCRE matches      Perl matches
1559        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
1560        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
1561        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
1563    For compatibility with Perl, \Q...\E sequences are recognized inside character
1564    classes as well as outside them.
1566    9. Re-organized 3 code statements in pcretest to avoid "overflow in
1567    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1568    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1569    signed/unsigned warnings.
1571    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1572    option for pcretest, so I've replaced it by a simple function that does just
1573    that job.
1575    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1576    "pcregrep -".
1578    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1579    Java package. This provides some syntactic sugar for simple cases of what my
1580    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1581    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1582    item, you can use this simplified notation. Note that only makes sense with
1583    greedy quantifiers. Consequently, the use of the possessive quantifier forces
1584    greediness, whatever the setting of the PCRE_UNGREEDY option.
1586    13. A change of greediness default within a pattern was not taking effect at
1587    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1588    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1589    was abstracted outside.
1591    14. PCRE now supports the \G assertion. It is true when the current matching
1592    position is at the start point of the match. This differs from \A when the
1593    starting offset is non-zero. Used with the /g option of pcretest (or similar
1594    code), it works in the same way as it does for Perl's /g option. If all
1595    alternatives of a regex begin with \G, the expression is anchored to the start
1596    match position, and the "anchored" flag is set in the compiled expression.
1598    15. Some bugs concerning the handling of certain option changes within patterns
1599    have been fixed. These applied to options other than (?ims). For example,
1600    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1601    been the other way round. Some of this was related to change 7 above.
1603    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1604    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1605    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1606    POSIX classes only within a class (e.g. /[[:alpha:]]/).
1608    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1609    mode. Unlike ".", it always matches newline, whatever the setting of
1610    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1611    assertions. Perl allows it, but it doesn't (in general) work because it can't
1612    calculate the length of the lookbehind. At least, that's the case for Perl
1613    5.8.0 - I've been told they are going to document that it doesn't work in
1614    future.
1616    18. Added an error diagnosis for escapes that PCRE does not support: these are
1617    \L, \l, \N, \P, \p, \U, \u, and \X.
1619    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1620    reading past the end of the pattern in cases such as /[abcd/.
1622    20. PCRE was getting more memory than necessary for patterns with classes that
1623    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1625    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1626    compiling PCRE for use with Virtual Pascal.
1628    22. Small fix to the Makefile to make it work properly if the build is done
1629    outside the source tree.
1631    23. Added a new extension: a condition to go with recursion. If a conditional
1632    subpattern starts with (?(R) the "true" branch is used if recursion has
1633    happened, whereas the "false" branch is used only at the top level.
1635    24. When there was a very long string of literal characters (over 255 bytes
1636    without UTF support, over 250 bytes with UTF support), the computation of how
1637    much memory was required could be incorrect, leading to segfaults or other
1638    strange effects.
1640    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1641    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1642    there was a subsequent back reference to those brackets. This meant that, for
1643    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1644    possible to check for precisely this case. All we can do is abandon the
1645    optimization if .* occurs inside capturing brackets when there are any back
1646    references whatsoever. (See below for a better fix that came later.)
1648    26. The handling of the optimization for finding the first character of a
1649    non-anchored pattern, and for finding a character that is required later in the
1650    match were failing in some cases. This didn't break the matching; it just
1651    failed to optimize when it could. The way this is done has been re-implemented.
1653    27. Fixed typo in error message for invalid (?R item (it said "(?p").
1655    28. Added a new feature that provides some of the functionality that Perl
1656    provides with (?{...}). The facility is termed a "callout". The way it is done
1657    in PCRE is for the caller to provide an optional function, by setting
1658    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1659    global variable. By default it is unset, which disables all calling out. To get
1660    the function called, the regex must include (?C) at appropriate points. This
1661    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1662    This provides a means of identifying different callout points. When PCRE
1663    reaches such a point in the regex, if pcre_callout has been set, the external
1664    function is called. It is provided with data in a structure called
1665    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1666    matching continues; if it returns a non-zero value, the match at the current
1667    point fails. However, backtracking will occur if possible. [This was changed
1668    later and other features added - see item 49 below.]
1670    29. pcretest is upgraded to test the callout functionality. It provides a
1671    callout function that displays information. By default, it shows the start of
1672    the match and the current position in the text. There are some new data escapes
1673    to vary what happens:
1675        \C+         in addition, show current contents of captured substrings
1676        \C-         do not supply a callout function
1677        \C!n        return 1 when callout number n is reached
1678        \C!n!m      return 1 when callout number n is reached for the mth time
1680    30. If pcregrep was called with the -l option and just a single file name, it
1681    output "<stdin>" if a match was found, instead of the file name.
1683    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1684    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1685    pcre_exec(). This saves a malloc/free per call. The default value of
1686    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1687    when configuring.
1689    32. The default maximum size of a compiled pattern is 64K. There have been a
1690    few cases of people hitting this limit. The code now uses macros to handle the
1691    storing of links as offsets within the compiled pattern. It defaults to 2-byte
1692    links, but this can be changed to 3 or 4 bytes by --with-link-size when
1693    configuring. Tests 2 and 5 work only with 2-byte links because they output
1694    debugging information about compiled patterns.
1696    33. Internal code re-arrangements:
1698    (a) Moved the debugging function for printing out a compiled regex into
1699        its own source file (printint.c) and used #include to pull it into
1700        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1701        separate copies.
1703    (b) Defined the list of op-code names for debugging as a macro in
1704        internal.h so that it is next to the definition of the opcodes.
1706    (c) Defined a table of op-code lengths for simpler skipping along compiled
1707        code. This is again a macro in internal.h so that it is next to the
1708        definition of the opcodes.
1710    34. Added support for recursive calls to individual subpatterns, along the
1711    lines of Robin Houston's patch (but implemented somewhat differently).
1713    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1714    allow it to read and process whole directories in Win32. This code was
1715    contributed by Lionel Fourquaux; it has not been tested by me.
1717    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1718    used to name a group. Names consist of alphanumerics and underscores, and must
1719    be unique. Back references use the syntax (?P=name) and recursive calls use
1720    (?P>name) which is a PCRE extension to the Python extension. Groups still have
1721    numbers. The function pcre_fullinfo() can be used after compilation to extract
1722    a name/number map. There are three relevant calls:
1724      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
1725      PCRE_INFO_NAMECOUNT            yields the number of entries
1726      PCRE_INFO_NAMETABLE            yields a pointer to the map.
1728    The map is a vector of fixed-size entries. The size of each entry depends on
1729    the length of the longest name used. The first two bytes of each entry are the
1730    group number, most significant byte first. There follows the corresponding
1731    name, zero terminated. The names are in alphabetical order.
1733    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1734    case instead of 255. Making it the same both with and without UTF-8 support
1735    means that the same test output works with both.
1737    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1738    calling malloc() with a zero argument.
1740    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1741    optimization. I've improved things by keeping a bitmap of backreferences with
1742    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1743    fact referenced, the optimization can be applied. It is unlikely that a
1744    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1745    the match to follow \n) will appear inside brackets with a number greater than
1746    31, but if it does, any back reference > 31 suppresses the optimization.
1748    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1749    of disabling numbered capturing parentheses. Any opening parenthesis that is
1750    not followed by ? behaves as if it were followed by ?: but named parentheses
1751    can still be used for capturing (and they will acquire numbers in the usual
1752    way).
1754    41. Redesigned the return codes from the match() function into yes/no/error so
1755    that errors can be passed back from deep inside the nested calls. A malloc
1756    failure while inside a recursive subpattern call now causes the
1757    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1759    42. It is now possible to set a limit on the number of times the match()
1760    function is called in a call to pcre_exec(). This facility makes it possible to
1761    limit the amount of recursion and backtracking, though not in a directly
1762    obvious way, because the match() function is used in a number of different
1763    circumstances. The count starts from zero for each position in the subject
1764    string (for non-anchored patterns). The default limit is, for compatibility, a
1765    large number, namely 10 000 000. You can change this in two ways:
1767    (a) When configuring PCRE before making, you can use --with-match-limit=n
1768        to set a default value for the compiled library.
1770    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1771        a different value is set. See 45 below.
1773    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1775    43. Added a new function pcre_config(int, void *) to enable run-time extraction
1776    of things that can be changed at compile time. The first argument specifies
1777    what is wanted and the second points to where the information is to be placed.
1778    The current list of available information is:
1780      PCRE_CONFIG_UTF8
1782    The output is an integer that is set to one if UTF-8 support is available;
1783    otherwise it is set to zero.
1787    The output is an integer that it set to the value of the code that is used for
1788    newline. It is either LF (10) or CR (13).
1792    The output is an integer that contains the number of bytes used for internal
1793    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
1797    The output is an integer that contains the threshold above which the POSIX
1798    interface uses malloc() for output vectors. See item 31 above.
1802    The output is an unsigned integer that contains the default limit of the number
1803    of match() calls in a pcre_exec() execution. See 42 above.
1805    44. pcretest has been upgraded by the addition of the -C option. This causes it
1806    to extract all the available output from the new pcre_config() function, and to
1807    output it. The program then exits immediately.
1809    45. A need has arisen to pass over additional data with calls to pcre_exec() in
1810    order to support additional features. One way would have been to define
1811    pcre_exec2() (for example) with extra arguments, but this would not have been
1812    extensible, and would also have required all calls to the original function to
1813    be mapped to the new one. Instead, I have chosen to extend the mechanism that
1814    is used for passing in "extra" data from pcre_study().
1816    The pcre_extra structure is now exposed and defined in pcre.h. It currently
1817    contains the following fields:
1819      flags         a bitmap indicating which of the following fields are set
1820      study_data    opaque data from pcre_study()
1821      match_limit   a way of specifying a limit on match() calls for a specific
1822                      call to pcre_exec()
1823      callout_data  data for callouts (see 49 below)
1825    The flag bits are also defined in pcre.h, and are
1831    The pcre_study() function now returns one of these new pcre_extra blocks, with
1832    the actual study data pointed to by the study_data field, and the
1833    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
1834    before. That is, this change is entirely upwards-compatible and requires no
1835    change to existing code.
1837    If you want to pass in additional data to pcre_exec(), you can either place it
1838    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
1839    block.
1841    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
1842    data string contains the escape sequence \M, pcretest calls pcre_exec() several
1843    times with different match limits, until it finds the minimum value needed for
1844    pcre_exec() to complete. The value is then output. This can be instructive; for
1845    most simple matches the number is quite small, but for pathological cases it
1846    gets very large very quickly.
1848    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
1849    returns the size of the data block pointed to by the study_data field in a
1850    pcre_extra block, that is, the value that was passed as the argument to
1851    pcre_malloc() when PCRE was getting memory in which to place the information
1852    created by pcre_study(). The fourth argument should point to a size_t variable.
1853    pcretest has been extended so that this information is shown after a successful
1854    pcre_study() call when information about the compiled regex is being displayed.
1856    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
1857    because what follows is always an absolute path. (Later: it turns out that this
1858    is more than cosmetic for MinGW, because it doesn't like empty path
1859    components.)
1861    49. Some changes have been made to the callout feature (see 28 above):
1863    (i)  A callout function now has three choices for what it returns:
1865           0  =>  success, carry on matching
1866         > 0  =>  failure at this point, but backtrack if possible
1867         < 0  =>  serious error, return this value from pcre_exec()
1869         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
1870         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
1871         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
1872         use by callout functions. It will never be used by PCRE itself.
1874    (ii) The pcre_extra structure (see 45 above) has a void * field called
1875         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
1876         pcre_callout_block structure has a field of the same name. The contents of
1877         the field passed in the pcre_extra structure are passed to the callout
1878         function in the corresponding field in the callout block. This makes it
1879         easier to use the same callout-containing regex from multiple threads. For
1880         testing, the pcretest program has a new data escape
1882           \C*n        pass the number n (may be negative) as callout_data
1884         If the callout function in pcretest receives a non-zero value as
1885         callout_data, it returns that value.
1887    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
1888    there were some redundant $(CFLAGS) in commands that are now specified as
1889    $(LINK), which already includes $(CFLAGS).
1891    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
1892    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
1893    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
1894    one-byte characters throughout. Note that case-insensitive matching applies
1895    only to characters whose values are less than 256. PCRE doesn't support the
1896    notion of cases for higher-valued characters.
1898    (i)   A character class whose characters are all within 0-255 is handled as
1899          a bit map, and the map is inverted for negative classes. Previously, a
1900          character > 255 always failed to match such a class; however it should
1901          match if the class was a negative one (e.g. [^ab]). This has been fixed.
1903    (ii)  A negated character class with a single character < 255 is coded as
1904          "not this character" (OP_NOT). This wasn't working properly when the test
1905          character was multibyte, either singly or repeated.
1907    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
1908          mode, for example: \x{100}{2,3}.
1910    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
1911          singly or repeated) now correctly test multibyte characters. However,
1912          PCRE doesn't recognize any characters with values greater than 255 as
1913          digits, spaces, or word characters. Such characters always match \D, \S,
1914          and \W, and never match \d, \s, or \w.
1916    (v)   Classes may now contain characters and character ranges with values
1917          greater than 255. For example: [ab\x{100}-\x{400}].
1919    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
1920          PCRE in UTF-8 mode.
1922    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
1923    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
1924    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
1925    value.)
1927    53. The single man page has become too large. I have therefore split it up into
1928    a number of separate man pages. These also give rise to individual HTML pages;
1929    these are now put in a separate directory, and there is an index.html page that
1930    lists them all. Some hyperlinking between the pages has been installed.
1932    54. Added convenience functions for handling named capturing parentheses.
1934    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
1935    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
1936    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
1937    are faulted.
1939    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
1940    calling configure. These values are used when compiling the dftables.c program
1941    which is run to generate the source of the default character tables. They
1942    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
1943    you will need to set these values.
1945    57. Updated the building process for Windows DLL, as provided by Fred Cox.
1948    Version 3.9 02-Jan-02
1949    ---------------------
1951    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
1953    2. If --disable-static was given, the building process failed when trying to
1954    build pcretest and pcregrep. (For some reason it was using libtool to compile
1955    them, which is not right, as they aren't part of the library.)
1958    Version 3.8 18-Dec-01
1959    ---------------------
1961    1. The experimental UTF-8 code was completely screwed up. It was packing the
1962    bytes in the wrong order. How dumb can you get?
1965    Version 3.7 29-Oct-01
1966    ---------------------
1968    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
1969    This caused pcretest, when used on the test data, to segfault. Unfortunately,
1970    this didn't happen under Solaris 8, where I normally test things.
1972    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
1973    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
1974    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
1975    this fix an hour or so after the initial 3.7 release.)
1978    Version 3.6 23-Oct-01
1979    ---------------------
1981    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
1982    offsets passed as NULL with zero offset count.
1984    2. The config.guess and config.sub files had not been updated when I moved to
1985    the latest autoconf.
1988    Version 3.5 15-Aug-01
1989    ---------------------
1991    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
1992    had been forgotten.
1994    2. By using declared but undefined structures, we can avoid using "void"
1995    definitions in pcre.h while keeping the internal definitions of the structures
1996    private.
1998    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
1999    user point of view, this means that both static and shared libraries are built
2000    by default, but this can be individually controlled. More of the work of
2001    handling this static/shared cases is now inside libtool instead of PCRE's make
2002    file.
2004    4. The pcretest utility is now installed along with pcregrep because it is
2005    useful for users (to test regexs) and by doing this, it automatically gets
2006    relinked by libtool. The documentation has been turned into a man page, so
2007    there are now .1, .txt, and .html versions in /doc.
2009    5. Upgrades to pcregrep:
2010       (i)   Added long-form option names like gnu grep.
2011       (ii)  Added --help to list all options with an explanatory phrase.
2012       (iii) Added -r, --recursive to recurse into sub-directories.
2013       (iv)  Added -f, --file to read patterns from a file.
2015    6. pcre_exec() was referring to its "code" argument before testing that
2016    argument for NULL (and giving an error if it was NULL).
2018    7. Upgraded Makefile.in to allow for compiling in a different directory from
2019    the source directory.
2021    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2022    options bits, the pointer it was passed was to an int instead of to an unsigned
2023    long int. This mattered only on 64-bit systems.
2025    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2026    generated) instead of pcre.in, which it its source. Also made the same change
2027    in several of the .c files.
2029    10. A new release of gcc defines printf() as a macro, which broke pcretest
2030    because it had an ifdef in the middle of a string argument for printf(). Fixed
2031    by using separate calls to printf().
2033    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2034    script, to force use of CR or LF instead of \n in the source. On non-Unix
2035    systems, the value can be set in config.h.
2037    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2038    absolute limit. Changed the text of the error message to make this clear, and
2039    likewise updated the man page.
2041    13. The limit of 99 on the number of capturing subpatterns has been removed.
2042    The new limit is 65535, which I hope will not be a "real" limit.
2045    Version 3.4 22-Aug-00
2046    ---------------------
2048    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2050    2. Diagnose condition (?(0) as an error instead of crashing on matching.
2053    Version 3.3 01-Aug-00
2054    ---------------------
2056    1. If an octal character was given, but the value was greater than \377, it
2057    was not getting masked to the least significant bits, as documented. This could
2058    lead to crashes in some systems.
2060    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2061    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2063    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2064    These just pass their arguments on to (pcre_free)(), but they are provided
2065    because some uses of PCRE bind it to non-C systems that can call its functions,
2066    but cannot call free() or pcre_free() directly.
2068    4. Add "make test" as a synonym for "make check". Corrected some comments in
2069    the Makefile.
2071    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2072    Makefile.
2074    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2075    command called pgrep for grepping around the active processes.
2077    7. Added the beginnings of support for UTF-8 character strings.
2079    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2080    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2081    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2082    out for the ar command.)
2085    Version 3.2 12-May-00
2086    ---------------------
2088    This is purely a bug fixing release.
2090    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
2091    of ZA. This was just one example of several cases that could provoke this bug,
2092    which was introduced by change 9 of version 2.00. The code for breaking
2093    infinite loops after an iteration that matches an empty string was't working
2094    correctly.
2096    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
2097    when matched against abbab (for example). After matching an empty string, it
2098    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
2099    caused it to match further down the string than it should.
2101    3. The code contained an inclusion of sys/types.h. It isn't clear why this
2102    was there because it doesn't seem to be needed, and it causes trouble on some
2103    systems, as it is not a Standard C header. It has been removed.
2105    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
2106    were reported on the Macintosh. The changes were from
2108      while ((c = *(++ptr)) != 0 && c != '\n');
2109    to
2110      while ((c = *(++ptr)) != 0 && c != '\n') ;
2112    Totally extraordinary, but if that's what it takes...
2114    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2115    available. Added HAVE_BCOPY and an autoconf test for it; if neither
2116    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2117    assumes the way PCRE uses memmove() (always moving upwards).
2119    6. PCRE is being used in one environment where strchr() is not available. There
2120    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2121    faster code anyway.
2124    Version 3.1 09-Feb-00
2125    ---------------------
2127    The only change in this release is the fixing of some bugs in Makefile.in for
2128    the "install" target:
2130    (1) It was failing to install pcreposix.h.
2132    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2135    Version 3.0 01-Feb-00
2136    ---------------------
2138    1. Add support for the /+ modifier to perltest (to output $` like it does in
2139    pcretest).
2141    2. Add support for the /g modifier to perltest.
2143    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2144    matches null strings.
2146    4. Fix perltest so that it doesn't do unwanted things when fed an empty
2147    pattern. Perl treats empty patterns specially - it reuses the most recent
2148    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2149    effect.
2151    5. The POSIX interface was broken in that it was just handing over the POSIX
2152    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2153    required a bigger vector, with some working space on the end. This means that
2154    the POSIX wrapper now has to get and free some memory, and copy the results.
2156    6. Added some simple autoconf support, placing the test data and the
2157    documentation in separate directories, re-organizing some of the
2158    information files, and making it build pcre-config (a GNU standard). Also added
2159    libtool support for building PCRE as a shared library, which is now the
2160    default.
2162    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2163    09 are not valid octal constants. Single digits will be used for minor values
2164    less than 10.
2166    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2167    existing programs that set these in the POSIX interface can use PCRE without
2168    modification.
2170    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2171    return all that pcre_info() returns, plus additional data. The pcre_info()
2172    function is retained for compatibility, but is considered to be obsolete.
2174    10. Added experimental recursion feature (?R) to handle one common case that
2175    Perl 5.6 will be able to do with (?p{...}).
2177    11. Added support for POSIX character classes like [:alpha:], which Perl is
2178    adopting.
2181    Version 2.08 31-Aug-99
2182    ----------------------
2184    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2185    trying to match at the startoffset position, but instead was moving forward to
2186    the next newline as if a previous match had failed.
2188    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2189    and could get into a loop if a null string was matched other than at the start
2190    of the subject.
2192    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2193    be distinguished at compile time, and for completeness also added PCRE_DATE.
2195    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2196    in GnuWin32 environments.
2199    Version 2.07 29-Jul-99
2200    ----------------------
2202    1. The documentation is now supplied in plain text form and HTML as well as in
2203    the form of man page sources.
2205    2. C++ compilers don't like assigning (void *) values to other pointer types.
2206    In particular this affects malloc(). Although there is no problem in Standard
2207    C, I've put in casts to keep C++ compilers happy.
2209    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2210    should be (const char *).
2212    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2213    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2214    However, I haven't made this a standard facility. The documentation doesn't
2215    mention it, and the Makefile doesn't support it.
2217    5. The Makefile now contains an "install" target, with editable destinations at
2218    the top of the file. The pcretest program is not installed.
2220    6. pgrep -V now gives the PCRE version number and date.
2222    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2223    causing the entire string to be ignored, instead of just the last character.
2225    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2226    non-matching string, it can take a very, very long time, even for strings of
2227    quite modest length, because of the nested recursion. PCRE now does better in
2228    some of these cases. It does this by remembering the last required literal
2229    character in the pattern, and pre-searching the subject to ensure it is present
2230    before running the real match. In other words, it applies a heuristic to detect
2231    some types of certain failure quickly, and in the above example, if presented
2232    with a string that has no trailing " it gives "no match" very quickly.
2234    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2235    other alternatives are tried instead.
2238    Version 2.06 09-Jun-99
2239    ----------------------
2241    1. Change pcretest's output for amount of store used to show just the code
2242    space, because the remainder (the data block) varies in size between 32-bit and
2243    64-bit systems.
2245    2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2246    start matching at. This allows lookbehinds to work when searching for multiple
2247    occurrences in a string.
2249    3. Added additional options to pcretest for testing multiple occurrences:
2251       /+   outputs the rest of the string that follows a match
2252       /g   loops for multiple occurrences, using the new startoffset argument
2253       /G   loops for multiple occurrences by passing an incremented pointer
2255    4. PCRE wasn't doing the "first character" optimization for patterns starting
2256    with \b or \B, though it was doing it for other lookbehind assertions. That is,
2257    it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2258    the letter 'x'. On long subject strings, this gives a significant speed-up.
2261    Version 2.05 21-Apr-99
2262    ----------------------
2264    1. Changed the type of magic_number from int to long int so that it works
2265    properly on 16-bit systems.
2267    2. Fixed a bug which caused patterns starting with .* not to work correctly
2268    when the subject string contained newline characters. PCRE was assuming
2269    anchoring for such patterns in all cases, which is not correct because .* will
2270    not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
2271    DOTALL is set at top level; otherwise it knows that patterns starting with .*
2272    must be retried after every newline in the subject.
2275    Version 2.04 18-Feb-99
2276    ----------------------
2278    1. For parenthesized subpatterns with repeats whose minimum was zero, the
2279    computation of the store needed to hold the pattern was incorrect (too large).
2280    If such patterns were nested a few deep, this could multiply and become a real
2281    problem.
2283    2. Added /M option to pcretest to show the memory requirement of a specific
2284    pattern. Made -m a synonym of -s (which does this globally) for compatibility.
2286    3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
2287    compiled in such a way that the backtracking after subsequent failure was
2288    pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
2289    ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
2292    Version 2.03 02-Feb-99
2293    ----------------------
2295    1. Fixed typo and small mistake in man page.
2297    2. Added 4th condition (GPL supersedes if conflict) and created separate
2298    LICENCE file containing the conditions.
2300    3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
2301    Perl, that is the internal \ allows the delimiter to be included in the
2302    pattern. Locked out the use of \ as a delimiter. If \ immediately follows
2303    the final delimiter, add \ to the end of the pattern (to test the error).
2305    4. Added the convenience functions for extracting substrings after a successful
2306    match. Updated pcretest to make it able to test these functions.
2309    Version 2.02 14-Jan-99
2310    ----------------------
2312    1. Initialized the working variables associated with each extraction so that
2313    their saving and restoring doesn't refer to uninitialized store.
2315    2. Put dummy code into study.c in order to trick the optimizer of the IBM C
2316    compiler for OS/2 into generating correct code. Apparently IBM isn't going to
2317    fix the problem.
2319    3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
2320    calls, and wasn't printing the correct value for compiling calls. Increased the
2321    default value of LOOPREPEAT, and the number of significant figures in the
2322    times.
2324    4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
2326    5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
2327    a building problem on Windows NT with a FAT file system.
2330    Version 2.01 21-Oct-98
2331    ----------------------
2333    1. Changed the API for pcre_compile() to allow for the provision of a pointer
2334    to character tables built by pcre_maketables() in the current locale. If NULL
2335    is passed, the default tables are used.
2338    Version 2.00 24-Sep-98
2339    ----------------------
2341    1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
2342    it any more.
2344    2. Allow quantification of (?>) groups, and make it work correctly.
2346    3. The first character computation wasn't working for (?>) groups.
2348    4. Correct the implementation of \Z (it is permitted to match on the \n at the
2349    end of the subject) and add 5.005's \z, which really does match only at the
2350    very end of the subject.
2352    5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
2354    6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
2355    DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
2356    localized options. All options to pcre_study() were also removed.
2358    7. Add other new features from 5.005:
2360       $(?<=           positive lookbehind
2361       $(?<!           negative lookbehind
2362       (?imsx-imsx)    added the unsetting capability
2363                       such a setting is global if at outer level; local otherwise
2364       (?imsx-imsx:)   non-capturing groups with option setting
2365       (?(cond)re|re)  conditional pattern matching
2367       A backreference to itself in a repeated group matches the previous
2368       captured string.
2370    8. General tidying up of studying (both automatic and via "study")
2371    consequential on the addition of new assertions.
2373    9. As in 5.005, unlimited repeated groups that could match an empty substring
2374    are no longer faulted at compile time. Instead, the loop is forcibly broken at
2375    runtime if any iteration does actually match an empty substring.
2377    10. Include the RunTest script in the distribution.
2379    11. Added tests from the Perl 5.005_02 distribution. This showed up a few
2380    discrepancies, some of which were old and were also with respect to 5.004. They
2381    have now been fixed.
2384    Version 1.09 28-Apr-98
2385    ----------------------
2387    1. A negated single character class followed by a quantifier with a minimum
2388    value of one (e.g.  [^x]{1,6}  ) was not compiled correctly. This could lead to
2389    program crashes, or just wrong answers. This did not apply to negated classes
2390    containing more than one character, or to minima other than one.
2393    Version 1.08 27-Mar-98
2394    ----------------------
2396    1. Add PCRE_UNGREEDY to invert the greediness of quantifiers.
2398    2. Add (?U) and (?X) to set PCRE_UNGREEDY and PCRE_EXTRA respectively. The
2399    latter must appear before anything that relies on it in the pattern.
2402    Version 1.07 16-Feb-98
2403    ----------------------
2405    1. A pattern such as /((a)*)*/ was not being diagnosed as in error (unlimited
2406    repeat of a potentially empty string).
2409    Version 1.06 23-Jan-98
2410    ----------------------
2412    1. Added Markus Oberhumer's little patches for C++.
2414    2. Literal strings longer than 255 characters were broken.
2417    Version 1.05 23-Dec-97
2418    ----------------------
2420    1. Negated character classes containing more than one character were failing if
2421    PCRE_CASELESS was set at run time.
2424    Version 1.04 19-Dec-97
2425    ----------------------
2427    1. Corrected the man page, where some "const" qualifiers had been omitted.
2429    2. Made debugging output print "{0,xxx}" instead of just "{,xxx}" to agree with
2430    input syntax.
2432    3. Fixed memory leak which occurred when a regex with back references was
2433    matched with an offsets vector that wasn't big enough. The temporary memory
2434    that is used in this case wasn't being freed if the match failed.
2436    4. Tidied pcretest to ensure it frees memory that it gets.
2438    5. Temporary memory was being obtained in the case where the passed offsets
2439    vector was exactly big enough.
2441    6. Corrected definition of offsetof() from change 5 below.
2443    7. I had screwed up change 6 below and broken the rules for the use of
2444    setjmp(). Now fixed.
2447    Version 1.03 18-Dec-97
2448    ----------------------
2450    1. A erroneous regex with a missing opening parenthesis was correctly
2451    diagnosed, but PCRE attempted to access brastack[-1], which could cause crashes
2452    on some systems.
2454    2. Replaced offsetof(real_pcre, code) by offsetof(real_pcre, code[0]) because
2455    it was reported that one broken compiler failed on the former because "code" is
2456    also an independent variable.
2458    3. The erroneous regex a[]b caused an array overrun reference.
2460    4. A regex ending with a one-character negative class (e.g. /[^k]$/) did not
2461    fail on data ending with that character. (It was going on too far, and checking
2462    the next character, typically a binary zero.) This was specific to the
2463    optimized code for single-character negative classes.
2465    5. Added a contributed patch from the TIN world which does the following:
2467      + Add an undef for memmove, in case the the system defines a macro for it.
2469      + Add a definition of offsetof(), in case there isn't one. (I don't know
2470        the reason behind this - offsetof() is part of the ANSI standard - but
2471        it does no harm).
2473      + Reduce the ifdef's in pcre.c using macro DPRINTF, thereby eliminating
2474        most of the places where whitespace preceded '#'. I have given up and
2475        allowed the remaining 2 cases to be at the margin.
2477      + Rename some variables in pcre to eliminate shadowing. This seems very
2478        pedantic, but does no harm, of course.
2480    6. Moved the call to setjmp() into its own function, to get rid of warnings
2481    from gcc -Wall, and avoided calling it at all unless PCRE_EXTRA is used.
2483    7. Constructs such as \d{8,} were compiling into the equivalent of
2484    \d{8}\d{0,65527} instead of \d{8}\d* which didn't make much difference to the
2485    outcome, but in this particular case used more store than had been allocated,
2486    which caused the bug to be discovered because it threw up an internal error.
2488    8. The debugging code in both pcre and pcretest for outputting the compiled
2489    form of a regex was going wrong in the case of back references followed by
2490    curly-bracketed repeats.
2493    Version 1.02 12-Dec-97
2494    ----------------------
2496    1. Typos in pcre.3 and comments in the source fixed.
2498    2. Applied a contributed patch to get rid of places where it used to remove
2499    'const' from variables, and fixed some signed/unsigned and uninitialized
2500    variable warnings.
2502    3. Added the "runtest" target to Makefile.
2504    4. Set default compiler flag to -O2 rather than just -O.
2507    Version 1.01 19-Nov-97
2508    ----------------------
2510    1. PCRE was failing to diagnose unlimited repeat of empty string for patterns
2511    like /([ab]*)*/, that is, for classes with more than one character in them.
2513    2. Likewise, it wasn't diagnosing patterns with "once-only" subpatterns, such
2514    as /((?>a*))*/ (a PCRE_EXTRA facility).
2517    Version 1.00 18-Nov-97
2518    ----------------------
2520    1. Added compile-time macros to support systems such as SunOS4 which don't have
2521    memmove() or strerror() but have other things that can be used instead.
2523    2. Arranged that "make clean" removes the executables.
2526  Version 0.99 27-Oct-97  Version 0.99 27-Oct-97
2527  ----------------------  ----------------------

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