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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.0 19-Dec-06
5    ---------------------
7     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
8        moving to gcc 4.1.1.
10     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
11        sys/time.h, which is documented as needed for this function. It doesn't
12        seem to matter on Linux, but it showed up on some releases of OS X.
14     3. It seems that there are systems where bytes whose values are greater than
15        127 match isprint() in the "C" locale. The "C" locale should be the
16        default when a C program starts up. In most systems, only ASCII printing
17        characters match isprint(). This difference caused the output from pcretest
18        to vary, making some of the tests fail. I have changed pcretest so that:
20        (a) When it is outputting text in the compiled version of a pattern, bytes
21            other than 32-126 are always shown as hex escapes.
23        (b) When it is outputting text that is a matched part of a subject string,
24            it does the same, unless a different locale has been set for the match
25            (using the /L modifier). In this case, it uses isprint() to decide.
27     4. Fixed a major bug that caused incorrect computation of the amount of memory
28        required for a compiled pattern when options that changed within the
29        pattern affected the logic of the preliminary scan that determines the
30        length. The relevant options are -x, and -i in UTF-8 mode. The result was
31        that the computed length was too small. The symptoms of this bug were
32        either the PCRE error "internal error: code overflow" from pcre_compile(),
33        or a glibc crash with a message such as "pcretest: free(): invalid next
34        size (fast)". Examples of patterns that provoked this bug (shown in
35        pcretest format) are:
37          /(?-x: )/x
38          /(?x)(?-x: \s*#\s*)/
39          /((?i)[\x{c0}])/8
40          /(?i:[\x{c0}])/8
42        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
43        is now done differently.
45     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
46        wrapper classes; (b) implement a new function in the C++ scanner that is
47        more efficient than the old way of doing things because it avoids levels of
48        recursion in the regex matching; (c) add a paragraph to the documentation
49        for the FullMatch() function.
51     6. The escape sequence \n was being treated as whatever was defined as
52        "newline". Not only was this contrary to the documentation, which states
53        that \n is character 10 (hex 0A), but it also went horribly wrong when
54        "newline" was defined as CRLF. This has been fixed.
56     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
57        was being set to -1 for the "end of line" case (supposedly a value that no
58        character can have). Though this value is never used (the check for end of
59        line is "zero bytes in current character"), it caused compiler complaints.
60        I've changed it to 0xffffffff.
62     8. In pcre_version.c, the version string was being built by a sequence of
63        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
64        string (as it is for production releases) called a macro with an empty
65        argument. The C standard says the result of this is undefined. The gcc
66        compiler treats it as an empty string (which was what was wanted) but it is
67        reported that Visual C gives an error. The source has been hacked around to
68        avoid this problem.
70     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
71        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
72        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
73        of them did).
75    10. Originally, pcretest opened its input and output without "b"; then I was
76        told that "b" was needed in some environments, so it was added for release
77        5.0 to both the input and output. (It makes no difference on Unix-like
78        systems.) Later I was told that it is wrong for the input on Windows. I've
79        now abstracted the modes into two macros, to make it easier to fiddle with
80        them, and removed "b" from the input mode under Windows.
82    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
84    12. Added -help and --help to pcretest as an official way of being reminded
85        of the options.
87    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
88        and pcrecpp.cc because they annoy compilers at high warning levels.
90    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
92    15. Fixed an occurrence of == in configure.ac that should have been = (shell
93        scripts are not C programs :-) and which was not noticed because it works
94        on Linux.
96    16. pcretest is supposed to handle any length of pattern and data line (as one
97        line or as a continued sequence of lines) by extending its input buffer if
98        necessary. This feature was broken for very long pattern lines, leading to
99        a string of junk being passed to pcre_compile() if the pattern was longer
100        than about 50K.
102    17. I have done a major re-factoring of the way pcre_compile() computes the
103        amount of memory needed for a compiled pattern. Previously, there was code
104        that made a preliminary scan of the pattern in order to do this. That was
105        OK when PCRE was new, but as the facilities have expanded, it has become
106        harder and harder to keep it in step with the real compile phase, and there
107        have been a number of bugs (see for example, 4 above). I have now found a
108        cunning way of running the real compile function in a "fake" mode that
109        enables it to compute how much memory it would need, while actually only
110        ever using a few hundred bytes of working memory and without too many
111        tests of the mode. This should make future maintenance and development
112        easier. A side effect of this work is that the limit of 200 on the nesting
113        depth of parentheses has been removed (though this was never a serious
114        limitation, I suspect). However, there is a downside: pcre_compile() now
115        runs more slowly than before (30% or more, depending on the pattern). I
116        hope this isn't a big issue. There is no effect on runtime performance.
118    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
119        newline (only possible for the last line of a file) and it was a
120        pattern that set a locale (followed by /Lsomething), pcretest crashed.
122    19. Added additional timing features to pcretest. (1) The -tm option now times
123        matching only, not compiling. (2) Both -t and -tm can be followed, as a
124        separate command line item, by a number that specifies the number of
125        repeats to use when timing. The default is 50000; this gives better
126        precision, but takes uncomfortably long for very large patterns.
128    20. Extended pcre_study() to be more clever in cases where a branch of a
129        subpattern has no definite first character. For example, (a*|b*)[cd] would
130        previously give no result from pcre_study(). Now it recognizes that the
131        first character must be a, b, c, or d.
133    21. There was an incorrect error "recursive call could loop indefinitely" if
134        a subpattern (or the entire pattern) that was being tested for matching an
135        empty string contained only one non-empty item after a nested subpattern.
136        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
137        incorrectly, because the \d was being skipped in the check.
139    22. The pcretest program now has a new pattern option /B and a command line
140        option -b, which is equivalent to adding /B to every pattern. This causes
141        it to show the compiled bytecode, without the additional information that
142        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
143        is the same as /B/I).
145    23. A new optimization is now able automatically to treat some sequences such
146        as a*b as a*+b. More specifically, if something simple (such as a character
147        or a simple class like \d) has an unlimited quantifier, and is followed by
148        something that cannot possibly match the quantified thing, the quantifier
149        is automatically "possessified".
151    24. A recursive reference to a subpattern whose number was greater than 39
152        went wrong under certain circumstances in UTF-8 mode. This bug could also
153        have affected the operation of pcre_study().
155    25. Realized that a little bit of performance could be had by replacing
156        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
158    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
160    27. Possessive quantifiers such as a++ were previously implemented by turning
161        them into atomic groups such as ($>a+). Now they have their own opcodes,
162        which improves performance. This includes the automatically created ones
163        from 23 above.
165    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
166        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
167        the first matched character to be a colon. This applied both to named and
168        numbered groups.
170    29. The ucpinternal.h header file was missing its idempotency #ifdef.
172    30. I was sent a "project" file called libpcre.a.dev which I understand makes
173        building PCRE on Windows easier, so I have included it in the distribution.
175    31. There is now a check in pcretest against a ridiculously large number being
176        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
177        loop, the loop is abandoned.
179    32. Forward references to subpatterns in conditions such as (?(2)...) where
180        subpattern 2 is defined later cause pcre_compile() to search forwards in
181        the pattern for the relevant set of parentheses. This search went wrong
182        when there were unescaped parentheses in a character class, parentheses
183        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
185    33. "Subroutine" calls and backreferences were previously restricted to
186        referencing subpatterns earlier in the regex. This restriction has now
187        been removed.
189    34. Added a number of extra features that are going to be in Perl 5.10. On the
190        whole, these are just syntactic alternatives for features that PCRE had
191        previously implemented using the Python syntax or my own invention. The
192        other formats are all retained for compatibility.
194        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
195            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
196            also .NET compatible.
198        (b) A recursion or subroutine call to a named group can now be defined as
199            (?&name) as well as (?P>name).
201        (c) A backreference to a named group can now be defined as \k<name> or
202            \k'name' as well as (?P=name). The new forms, as well as being in Perl
203            5.10, are also .NET compatible.
205        (d) A conditional reference to a named group can now use the syntax
206            (?(<name>) or (?('name') as well as (?(name).
208        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
209            groups (named and numbered) that are never evaluated inline, but can be
210            called as "subroutines" from elsewhere. In effect, the DEFINE condition
211            is always false. There may be only one alternative in such a group.
213        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
214            as the simple (?(R). The condition is true only if the most recent
215            recursion is that of the given number or name. It does not search out
216            through the entire recursion stack.
218        (g) The escape \gN or \g{N} has been added, where N is a positive or
219            negative number, specifying an absolute or relative reference.
221    35. Tidied to get rid of some further signed/unsigned compiler warnings and
222        some "unreachable code" warnings.
224    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
225        things, this adds five new scripts.
227    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
228        There were also incompatibilities regarding the handling of \Q..\E inside
229        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
230        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
232    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
233        matches an empty string, and forcibly breaks the loop. There were bugs in
234        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
235        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
236        separate and independent bugs (that affected different cases) have been
237        fixed.
239    39. Refactored the code to abolish the use of different opcodes for small
240        capturing bracket numbers. This is a tidy that I avoided doing when I
241        removed the limit on the number of capturing brackets for 3.5 back in 2001.
242        The new approach is not only tidier, it makes it possible to reduce the
243        memory needed to fix the previous bug (38).
245    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
246        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
247        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
248        mode.
250    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
251        report.
253    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
254        copy construction and assignment in the C++ wrapper.
256    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
257        couple of bugs that could have given wrong results in the "--newline=crlf"
258        case.
260    44. Added a number of casts and did some reorganization of signed/unsigned int
261        variables following suggestions from Dair Grant. Also renamed the variable
262        "this" as "item" because it is a C++ keyword.
264    45. Arranged for dftables to add
266          #include "pcre_internal.h"
268        to pcre_chartables.c because without it, gcc 4.x may remove the array
269        definition from the final binary if PCRE is built into a static library and
270        dead code stripping is activated.
272    46. For an unanchored pattern, if a match attempt fails at the start of a
273        newline sequence, and the newline setting is CRLF or ANY, and the next two
274        characters are CRLF, advance by two characters instead of one.
277    Version 6.7 04-Jul-06
278    ---------------------
280     1. In order to handle tests when input lines are enormously long, pcretest has
281        been re-factored so that it automatically extends its buffers when
282        necessary. The code is crude, but this _is_ just a test program. The
283        default size has been increased from 32K to 50K.
285     2. The code in pcre_study() was using the value of the re argument before
286        testing it for NULL. (Of course, in any sensible call of the function, it
287        won't be NULL.)
289     3. The memmove() emulation function in pcre_internal.h, which is used on
290        systems that lack both memmove() and bcopy() - that is, hardly ever -
291        was missing a "static" storage class specifier.
293     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
294        containing an extended class (one that cannot be represented by a bitmap
295        because it contains high-valued characters or Unicode property items, e.g.
296        [\pZ]). Almost always one would set UTF-8 mode when processing such a
297        pattern, but PCRE should not loop if you do not (it no longer does).
298        [Detail: two cases were found: (a) a repeated subpattern containing an
299        extended class; (b) a recursive reference to a subpattern that followed a
300        previous extended class. It wasn't skipping over the extended class
301        correctly when UTF-8 mode was not set.]
303     5. A negated single-character class was not being recognized as fixed-length
304        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
305        compile error "lookbehind assertion is not fixed length".
307     6. The RunPerlTest auxiliary script was showing an unexpected difference
308        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
309        write a Perl script that can interpret lines of an input file either as
310        byte characters or as UTF-8, which is what "perltest" was being required to
311        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
312        can't do is switch easily at run time between having the "use utf8;" pragma
313        or not. In the end, I fudged it by using the RunPerlTest script to insert
314        "use utf8;" explicitly for the UTF-8 tests.
316     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
317        the end of the subject string, contrary to the documentation and to what
318        Perl does. This was true of both matching functions. Now it matches only at
319        the start of the subject and immediately after *internal* newlines.
321     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
322        a pointer to an int instead of a pointer to an unsigned long int. This
323        caused problems on 64-bit systems.
325     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
326        instance of the 'standard' template library not being so standard".
328    10. There was no check on the number of named subpatterns nor the maximum
329        length of a subpattern name. The product of these values is used to compute
330        the size of the memory block for a compiled pattern. By supplying a very
331        long subpattern name and a large number of named subpatterns, the size
332        computation could be caused to overflow. This is now prevented by limiting
333        the length of names to 32 characters, and the number of named subpatterns
334        to 10,000.
336    11. Subpatterns that are repeated with specific counts have to be replicated in
337        the compiled pattern. The size of memory for this was computed from the
338        length of the subpattern and the repeat count. The latter is limited to
339        65535, but there was no limit on the former, meaning that integer overflow
340        could in principle occur. The compiled length of a repeated subpattern is
341        now limited to 30,000 bytes in order to prevent this.
343    12. Added the optional facility to have named substrings with the same name.
345    13. Added the ability to use a named substring as a condition, using the
346        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
347        are numbers (not recommended). Forward references are permitted.
349    14. Added forward references in named backreferences (if you see what I mean).
351    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
352        pattern could run off the end of the subject. For example, the pattern
353        "(?s)(.{1,5})"8 did this with the subject "ab".
355    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
356        PCRE_CASELESS was set when matching characters that were quantified with ?
357        or *.
359    17. A character class other than a single negated character that had a minimum
360        but no maximum quantifier - for example [ab]{6,} - was not handled
361        correctly by pce_dfa_exec(). It would match only one character.
363    18. A valid (though odd) pattern that looked like a POSIX character
364        class but used an invalid character after [ (for example [[,abc,]]) caused
365        pcre_compile() to give the error "Failed: internal error: code overflow" or
366        in some cases to crash with a glibc free() error. This could even happen if
367        the pattern terminated after [[ but there just happened to be a sequence of
368        letters, a binary zero, and a closing ] in the memory that followed.
370    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
371        over the years. Originally (before any Unicode support), just the bottom 8
372        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
373        output from "man perlunicode" includes this:
375          The regular expression compiler produces polymorphic opcodes.  That
376          is, the pattern adapts to the data and automatically switches to
377          the Unicode character scheme when presented with Unicode data--or
378          instead uses a traditional byte scheme when presented with byte
379          data.
381        Sadly, a wide octal escape does not cause a switch, and in a string with
382        no other multibyte characters, these octal escapes are treated as before.
383        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
384        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
385        Unicode string.
387        I have not perpetrated such confusion in PCRE. Up till now, it took just
388        the bottom 8 bits, as in old Perl. I have now made octal escapes with
389        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
390        translate to the appropriate multibyte character.
392    29. Applied some refactoring to reduce the number of warnings from Microsoft
393        and Borland compilers. This has included removing the fudge introduced
394        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
395        a warning about an unused variable.
397    21. PCRE has not included VT (character 0x0b) in the set of whitespace
398        characters since release 4.0, because Perl (from release 5.004) does not.
399        [Or at least, is documented not to: some releases seem to be in conflict
400        with the documentation.] However, when a pattern was studied with
401        pcre_study() and all its branches started with \s, PCRE still included VT
402        as a possible starting character. Of course, this did no harm; it just
403        caused an unnecessary match attempt.
405    22. Removed a now-redundant internal flag bit that recorded the fact that case
406        dependency changed within the pattern. This was once needed for "required
407        byte" processing, but is no longer used. This recovers a now-scarce options
408        bit. Also moved the least significant internal flag bit to the most-
409        significant bit of the word, which was not previously used (hangover from
410        the days when it was an int rather than a uint) to free up another bit for
411        the future.
413    23. Added support for CRLF line endings as well as CR and LF. As well as the
414        default being selectable at build time, it can now be changed at runtime
415        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
416        specify that it is scanning data with non-default line endings.
418    24. Changed the definition of CXXLINK to make it agree with the definition of
419        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
421    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
422        recursions. This makes a big different to stack usage for some patterns.
424    26. If a subpattern containing a named recursion or subroutine reference such
425        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
426        the space required for the compiled pattern went wrong and gave too small a
427        value. Depending on the environment, this could lead to "Failed: internal
428        error: code overflow at offset 49" or "glibc detected double free or
429        corruption" errors.
431    27. Applied patches from Google (a) to support the new newline modes and (b) to
432        advance over multibyte UTF-8 characters in GlobalReplace.
434    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
435        difference for some implementation of PCRE in some Windows version.
437    29. Added some extra testing facilities to pcretest:
439        \q<number>   in a data line sets the "match limit" value
440        \Q<number>   in a data line sets the "match recursion limt" value
441        -S <number>  sets the stack size, where <number> is in megabytes
443        The -S option isn't available for Windows.
446    Version 6.6 06-Feb-06
447    ---------------------
449     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
450        in pcreposix.h. I have copied the definition from pcre.h.
452     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
453        because pcre.h is no longer a built file.
455     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
456        not normally included in the compiled code.
459    Version 6.5 01-Feb-06
460    ---------------------
462     1. When using the partial match feature with pcre_dfa_exec(), it was not
463        anchoring the second and subsequent partial matches at the new starting
464        point. This could lead to incorrect results. For example, with the pattern
465        /1234/, partially matching against "123" and then "a4" gave a match.
467     2. Changes to pcregrep:
469        (a) All non-match returns from pcre_exec() were being treated as failures
470            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
471            error message is output. Some extra information is given for the
472            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
473            probably the only errors that are likely to be caused by users (by
474            specifying a regex that has nested indefinite repeats, for instance).
475            If there are more than 20 of these errors, pcregrep is abandoned.
477        (b) A binary zero was treated as data while matching, but terminated the
478            output line if it was written out. This has been fixed: binary zeroes
479            are now no different to any other data bytes.
481        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
482            used to set a locale for matching. The --locale=xxxx long option has
483            been added (no short equivalent) to specify a locale explicitly on the
484            pcregrep command, overriding the environment variables.
486        (d) When -B was used with -n, some line numbers in the output were one less
487            than they should have been.
489        (e) Added the -o (--only-matching) option.
491        (f) If -A or -C was used with -c (count only), some lines of context were
492            accidentally printed for the final match.
494        (g) Added the -H (--with-filename) option.
496        (h) The combination of options -rh failed to suppress file names for files
497            that were found from directory arguments.
499        (i) Added the -D (--devices) and -d (--directories) options.
501        (j) Added the -F (--fixed-strings) option.
503        (k) Allow "-" to be used as a file name for -f as well as for a data file.
505        (l) Added the --colo(u)r option.
507        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
508            is not present by default.
510     3. A nasty bug was discovered in the handling of recursive patterns, that is,
511        items such as (?R) or (?1), when the recursion could match a number of
512        alternatives. If it matched one of the alternatives, but subsequently,
513        outside the recursion, there was a failure, the code tried to back up into
514        the recursion. However, because of the way PCRE is implemented, this is not
515        possible, and the result was an incorrect result from the match.
517        In order to prevent this happening, the specification of recursion has
518        been changed so that all such subpatterns are automatically treated as
519        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
521     4. I had overlooked the fact that, in some locales, there are characters for
522        which isalpha() is true but neither isupper() nor islower() are true. In
523        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
524        and ordfeminine) are like this. This affected the treatment of \w and \W
525        when they appeared in character classes, but not when they appeared outside
526        a character class. The bit map for "word" characters is now created
527        separately from the results of isalnum() instead of just taking it from the
528        upper, lower, and digit maps. (Plus the underscore character, of course.)
530     5. The above bug also affected the handling of POSIX character classes such as
531        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
532        permanent tables. Instead, the bit maps for such a class were previously
533        created as the appropriate unions of the upper, lower, and digit bitmaps.
534        Now they are created by subtraction from the [[:word:]] class, which has
535        its own bitmap.
537     6. The [[:blank:]] character class matches horizontal, but not vertical space.
538        It is created by subtracting the vertical space characters (\x09, \x0a,
539        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
540        subtraction was done in the overall bitmap for a character class, meaning
541        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
542        be recognized. This bug has been fixed.
544     7. Patches from the folks at Google:
546          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
547          real life, but is still worth protecting against".
549          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
550          regular expressions".
552          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
553          have it.
555          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
556          "configure" and the latter not, in order to fix a problem somebody had
557          with compiling the Arg class on HP-UX.
559          (e) Improve the error-handling of the C++ wrapper a little bit.
561          (f) New tests for checking recursion limiting.
563     8. The pcre_memmove() function, which is used only if the environment does not
564        have a standard memmove() function (and is therefore rarely compiled),
565        contained two bugs: (a) use of int instead of size_t, and (b) it was not
566        returning a result (though PCRE never actually uses the result).
568     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
569        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
570        returned instead of calling malloc() with an overflowing number that would
571        most likely cause subsequent chaos.
573    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
575    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
576        with this option is matched, the nmatch and pmatch options of regexec() are
577        ignored.
579    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
580        provided in case anyone wants to the the POSIX interface with UTF-8
581        strings.
583    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
584        C++ linking (needed for some HP-UX environments).
586    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
587        (unused parameter) and in the pcre_printint() function (omitted "default"
588        switch label when the default is to do nothing).
590    15. Added some code to make it possible, when PCRE is compiled as a C++
591        library, to replace subject pointers for pcre_exec() with a smart pointer
592        class, thus making it possible to process discontinuous strings.
594    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
595        much the same function. They were added by different people who were trying
596        to make PCRE easy to compile on non-Unix systems. It has been suggested
597        that PCRE_EXPORT be abolished now that there is more automatic apparatus
598        for compiling on Windows systems. I have therefore replaced it with
599        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
600        defaults to "extern" for C or "extern C" for C++, which works fine on
601        Unix-like systems. It is now possible to override the value of PCRE_DATA_
602        SCOPE with something explicit in config.h. In addition:
604        (a) pcreposix.h still had just "extern" instead of either of these macros;
605            I have replaced it with PCRE_DATA_SCOPE.
607        (b) Functions such as _pcre_xclass(), which are internal to the library,
608            but external in the C sense, all had PCRE_EXPORT in their definitions.
609            This is apparently wrong for the Windows case, so I have removed it.
610            (It makes no difference on Unix-like systems.)
612    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
613        of recursive calls to match(). This is different to MATCH_LIMIT because
614        that limits the total number of calls to match(), not all of which increase
615        the depth of recursion. Limiting the recursion depth limits the amount of
616        stack (or heap if NO_RECURSE is set) that is used. The default can be set
617        when PCRE is compiled, and changed at run time. A patch from Google adds
618        this functionality to the C++ interface.
620    18. Changes to the handling of Unicode character properties:
622        (a) Updated the table to Unicode 4.1.0.
624        (b) Recognize characters that are not in the table as "Cn" (undefined).
626        (c) I revised the way the table is implemented to a much improved format
627            which includes recognition of ranges. It now supports the ranges that
628            are defined in UnicodeData.txt, and it also amalgamates other
629            characters into ranges. This has reduced the number of entries in the
630            table from around 16,000 to around 3,000, thus reducing its size
631            considerably. I realized I did not need to use a tree structure after
632            all - a binary chop search is just as efficient. Having reduced the
633            number of entries, I extended their size from 6 bytes to 8 bytes to
634            allow for more data.
636        (d) Added support for Unicode script names via properties such as \p{Han}.
638    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
639        matching that character.
641    20. When matching a repeated Unicode property with a minimum greater than zero,
642        (for example \pL{2,}), PCRE could look past the end of the subject if it
643        reached it while seeking the minimum number of characters. This could
644        happen only if some of the characters were more than one byte long, because
645        there is a check for at least the minimum number of bytes.
647    21. Refactored the implementation of \p and \P so as to be more general, to
648        allow for more different types of property in future. This has changed the
649        compiled form incompatibly. Anybody with saved compiled patterns that use
650        \p or \P will have to recompile them.
652    22. Added "Any" and "L&" to the supported property types.
654    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
655        but give a compile time error if the value is greater than 0xff.
657    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
658        accidentally not being installed or uninstalled.
660    25. The pcre.h file was built from pcre.h.in, but the only changes that were
661        made were to insert the current release number. This seemed silly, because
662        it made things harder for people building PCRE on systems that don't run
663        "configure". I have turned pcre.h into a distributed file, no longer built
664        by "configure", with the version identification directly included. There is
665        no longer a pcre.h.in file.
667        However, this change necessitated a change to the pcre-config script as
668        well. It is built from pcre-config.in, and one of the substitutions was the
669        release number. I have updated configure.ac so that ./configure now finds
670        the release number by grepping pcre.h.
672    26. Added the ability to run the tests under valgrind.
675    Version 6.4 05-Sep-05
676    ---------------------
678     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
679        "--" to be printed when multiple files were scanned, even when none of the
680        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
681        consider it to be a bug, and have restored the previous behaviour.
683     2. A couple of code tidies to get rid of compiler warnings.
685     3. The pcretest program used to cheat by referring to symbols in the library
686        whose names begin with _pcre_. These are internal symbols that are not
687        really supposed to be visible externally, and in some environments it is
688        possible to suppress them. The cheating is now confined to including
689        certain files from the library's source, which is a bit cleaner.
691     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
692        file's purpose clearer.
694     5. Reorganized pcre_ucp_findchar().
697    Version 6.3 15-Aug-05
698    ---------------------
700     1. The file libpcre.pc.in did not have general read permission in the tarball.
702     2. There were some problems when building without C++ support:
704        (a) If C++ support was not built, "make install" and "make test" still
705            tried to test it.
707        (b) There were problems when the value of CXX was explicitly set. Some
708            changes have been made to try to fix these, and ...
710        (c) --disable-cpp can now be used to explicitly disable C++ support.
712        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
713            backslash in a target when C++ was disabled. This confuses some
714            versions of "make", apparently. Using an intermediate variable solves
715            this. (Same for CPP_LOBJ.)
717     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
718        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
719        necessary on certain architectures.
721     4. Added a setting of -export-symbols-regex to the link command to remove
722        those symbols that are exported in the C sense, but actually are local
723        within the library, and not documented. Their names all begin with
724        "_pcre_". This is not a perfect job, because (a) we have to except some
725        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
726        available (and never for static libraries). I have made a note to try to
727        find a way round (a) in the future.
730    Version 6.2 01-Aug-05
731    ---------------------
733     1. There was no test for integer overflow of quantifier values. A construction
734        such as {1111111111111111} would give undefined results. What is worse, if
735        a minimum quantifier for a parenthesized subpattern overflowed and became
736        negative, the calculation of the memory size went wrong. This could have
737        led to memory overwriting.
739     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
741     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
742        operating environments where this matters.
744     4. Applied Giuseppe Maxia's patch to add additional features for controlling
745        PCRE options from within the C++ wrapper.
747     5. Named capturing subpatterns were not being correctly counted when a pattern
748        was compiled. This caused two problems: (a) If there were more than 100
749        such subpatterns, the calculation of the memory needed for the whole
750        compiled pattern went wrong, leading to an overflow error. (b) Numerical
751        back references of the form \12, where the number was greater than 9, were
752        not recognized as back references, even though there were sufficient
753        previous subpatterns.
755     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
756        versions of gcc, e.g. 2.95.4.
759    Version 6.1 21-Jun-05
760    ---------------------
762     1. There was one reference to the variable "posix" in pcretest.c that was not
763        surrounded by "#if !defined NOPOSIX".
765     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
766        the cross-check on the old pcre_info() function, for the benefit of the
767        cut-down version of PCRE that is currently imported into Exim.
769     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
770        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
771        patterns that start (?i) but I don't think that matters. The use of (?i) is
772        just an example; this all applies to the other options as well.
774     4. Since libtool seems to echo the compile commands it is issuing, the output
775        from "make" can be reduced a bit by putting "@" in front of each libtool
776        compile command.
778     5. Patch from the folks at Google for configure.in to be a bit more thorough
779        in checking for a suitable C++ installation before trying to compile the
780        C++ stuff. This should fix a reported problem when a compiler was present,
781        but no suitable headers.
783     6. The man pages all had just "PCRE" as their title. I have changed them to
784        be the relevant file name. I have also arranged that these names are
785        retained in the file doc/pcre.txt, which is a concatenation in text format
786        of all the man pages except the little individual ones for each function.
788     7. The NON-UNIX-USE file had not been updated for the different set of source
789        files that come with release 6. I also added a few comments about the C++
790        wrapper.
793    Version 6.0 07-Jun-05
794    ---------------------
796     1. Some minor internal re-organization to help with my DFA experiments.
798     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
799        didn't matter for the library itself when fully configured, but did matter
800        when compiling without UCP support, or within Exim, where the ucp files are
801        not imported.
803     3. Refactoring of the library code to split up the various functions into
804        different source modules. The addition of the new DFA matching code (see
805        below) to a single monolithic source would have made it really too
806        unwieldy, quite apart from causing all the code to be include in a
807        statically linked application, when only some functions are used. This is
808        relevant even without the DFA addition now that patterns can be compiled in
809        one application and matched in another.
811        The downside of splitting up is that there have to be some external
812        functions and data tables that are used internally in different modules of
813        the library but which are not part of the API. These have all had their
814        names changed to start with "_pcre_" so that they are unlikely to clash
815        with other external names.
817     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
818        a different (DFA) algorithm. Although it is slower than the original
819        function, it does have some advantages for certain types of matching
820        problem.
822     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
823        including restarting after a partial match.
825     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
826        defined when compiling for Windows was sent to me. I have put it into the
827        code, though I have no means of testing or verifying it.
829     7. Added the pcre_refcount() auxiliary function.
831     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
832        match before or at the first newline in the subject string. In pcretest,
833        the /f option on a pattern can be used to set this.
835     9. A repeated \w when used in UTF-8 mode with characters greater than 256
836        would behave wrongly. This has been present in PCRE since release 4.0.
838    10. A number of changes to the pcregrep command:
840        (a) Refactored how -x works; insert ^(...)$ instead of setting
841            PCRE_ANCHORED and checking the length, in preparation for adding
842            something similar for -w.
844        (b) Added the -w (match as a word) option.
846        (c) Refactored the way lines are read and buffered so as to have more
847            than one at a time available.
849        (d) Implemented a pcregrep test script.
851        (e) Added the -M (multiline match) option. This allows patterns to match
852            over several lines of the subject. The buffering ensures that at least
853            8K, or the rest of the document (whichever is the shorter) is available
854            for matching (and similarly the previous 8K for lookbehind assertions).
856        (f) Changed the --help output so that it now says
858              -w, --word-regex(p)
860            instead of two lines, one with "regex" and the other with "regexp"
861            because that confused at least one person since the short forms are the
862            same. (This required a bit of code, as the output is generated
863            automatically from a table. It wasn't just a text change.)
865        (g) -- can be used to terminate pcregrep options if the next thing isn't an
866            option but starts with a hyphen. Could be a pattern or a path name
867            starting with a hyphen, for instance.
869        (h) "-" can be given as a file name to represent stdin.
871        (i) When file names are being printed, "(standard input)" is used for
872            the standard input, for compatibility with GNU grep. Previously
873            "<stdin>" was used.
875        (j) The option --label=xxx can be used to supply a name to be used for
876            stdin when file names are being printed. There is no short form.
878        (k) Re-factored the options decoding logic because we are going to add
879            two more options that take data. Such options can now be given in four
880            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
882        (l) Added the -A, -B, and -C options for requesting that lines of context
883            around matches be printed.
885        (m) Added the -L option to print the names of files that do not contain
886            any matching lines, that is, the complement of -l.
888        (n) The return code is 2 if any file cannot be opened, but pcregrep does
889            continue to scan other files.
891        (o) The -s option was incorrectly implemented. For compatibility with other
892            greps, it now suppresses the error message for a non-existent or non-
893            accessible file (but not the return code). There is a new option called
894            -q that suppresses the output of matching lines, which was what -s was
895            previously doing.
897        (p) Added --include and --exclude options to specify files for inclusion
898            and exclusion when recursing.
900    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
901        Hopefully, it now does.
903    12. Missing cast in pcre_study().
905    13. Added an "uninstall" target to the makefile.
907    14. Replaced "extern" in the function prototypes in Makefile.in with
908        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
909        world, but is set differently for Windows.
911    15. Added a second compiling function called pcre_compile2(). The only
912        difference is that it has an extra argument, which is a pointer to an
913        integer error code. When there is a compile-time failure, this is set
914        non-zero, in addition to the error test pointer being set to point to an
915        error message. The new argument may be NULL if no error number is required
916        (but then you may as well call pcre_compile(), which is now just a
917        wrapper). This facility is provided because some applications need a
918        numeric error indication, but it has also enabled me to tidy up the way
919        compile-time errors are handled in the POSIX wrapper.
921    16. Added VPATH=.libs to the makefile; this should help when building with one
922        prefix path and installing with another. (Or so I'm told by someone who
923        knows more about this stuff than I do.)
925    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
926        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
927        match everything, including newlines. This is not POSIX-compatible, but
928        somebody wanted the feature. From pcretest it can be activated by using
929        both the P and the s flags.
931    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
933    19. libpcre.pc was being incorrectly installed as executable.
935    20. A couple of places in pcretest check for end-of-line by looking for '\n';
936        it now also looks for '\r' so that it will work unmodified on Windows.
938    21. Added Google's contributed C++ wrapper to the distribution.
940    22. Added some untidy missing memory free() calls in pcretest, to keep
941        Electric Fence happy when testing.
945    Version 5.0 13-Sep-04
946    ---------------------
948     1. Internal change: literal characters are no longer packed up into items
949        containing multiple characters in a single byte-string. Each character
950        is now matched using a separate opcode. However, there may be more than one
951        byte in the character in UTF-8 mode.
953     2. The pcre_callout_block structure has two new fields: pattern_position and
954        next_item_length. These contain the offset in the pattern to the next match
955        item, and its length, respectively.
957     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
958        insertion of callouts before each pattern item. Added the /C option to
959        pcretest to make use of this.
961     4. On the advice of a Windows user, the lines
963          #if defined(_WIN32) || defined(WIN32)
964          _setmode( _fileno( stdout ), 0x8000 );
965          #endif  /* defined(_WIN32) || defined(WIN32) */
967        have been added to the source of pcretest. This apparently does useful
968        magic in relation to line terminators.
970     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
971        for the benefit of those environments where the "b" makes a difference.
973     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
974        to know about it. I have put a hack into configure.in that adds in code
975        to set GCC=yes if CC=icc. This seems to end up at a point in the
976        generated configure script that is early enough to affect the setting of
977        compiler options, which is what is needed, but I have no means of testing
978        whether it really works. (The user who reported this had patched the
979        generated configure script, which of course I cannot do.)
981        LATER: After change 22 below (new libtool files), the configure script
982        seems to know about icc (and also ecc). Therefore, I have commented out
983        this hack in configure.in.
985     7. Added support for pkg-config (2 patches were sent in).
987     8. Negated POSIX character classes that used a combination of internal tables
988        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
989        [[:^ascii]]. Typically, they would match almost any characters. The other
990        POSIX classes were not broken in this way.
992     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
993        to find the match, as PCRE was deluded into thinking that the match had to
994        start at the start point or following a newline. The same bug applied to
995        patterns with negative forward assertions or any backward assertions
996        preceding ".*" at the start, unless the pattern required a fixed first
997        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
999    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1000        starting at the last subject character, bytes beyond the end of the subject
1001        string were read.
1003    11. Renamed the variable "class" as "classbits" to make life easier for C++
1004        users. (Previously there was a macro definition, but it apparently wasn't
1005        enough.)
1007    12. Added the new field "tables" to the extra data so that tables can be passed
1008        in at exec time, or the internal tables can be re-selected. This allows
1009        a compiled regex to be saved and re-used at a later time by a different
1010        program that might have everything at different addresses.
1012    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1013        -R library as well as a -L library.
1015    14. The debugging options of pcretest (-d on the command line or D on a
1016        pattern) showed incorrect output for anything following an extended class
1017        that contained multibyte characters and which was followed by a quantifier.
1019    15. Added optional support for general category Unicode character properties
1020        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1021        support. It adds about 90K to the size of the library. The meanings of the
1022        inbuilt class escapes such as \d and \s have NOT been changed.
1024    16. Updated pcredemo.c to include calls to free() to release the memory for the
1025        compiled pattern.
1027    17. The generated file chartables.c was being created in the source directory
1028        instead of in the building directory. This caused the build to fail if the
1029        source directory was different from the building directory, and was
1030        read-only.
1032    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1033        file. No doubt somebody will tell me if they don't make sense... Also added
1034        Dan Mooney's comments about building on OpenVMS.
1036    19. Added support for partial matching via the PCRE_PARTIAL option for
1037        pcre_exec() and the \P data escape in pcretest.
1039    20. Extended pcretest with 3 new pattern features:
1041        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1042              write the compiled pattern to the file whose name is "rest-of-line".
1043              This is a straight binary dump of the data, with the saved pointer to
1044              the character tables forced to be NULL. The study data, if any, is
1045              written too. After writing, pcretest reads a new pattern.
1047        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1048              compiled pattern from the given file. There must not be any
1049              occurrences of "<" in the file name (pretty unlikely); if there are,
1050              pcretest will instead treat the initial "<" as a pattern delimiter.
1051              After reading in the pattern, pcretest goes on to read data lines as
1052              usual.
1054        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1055              and 16-bit fields in a compiled pattern, to simulate a pattern that
1056              was compiled on a host of opposite endianness.
1058    21. The pcre-exec() function can now cope with patterns that were compiled on
1059        hosts of opposite endianness, with this restriction:
1061          As for any compiled expression that is saved and used later, the tables
1062          pointer field cannot be preserved; the extra_data field in the arguments
1063          to pcre_exec() should be used to pass in a tables address if a value
1064          other than the default internal tables were used at compile time.
1066    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1067        now diagnosed as an error. Previously, most of the time, a negative number
1068        would have been treated as zero, but if in addition "ovector" was passed as
1069        NULL, a crash could occur.
1071    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1072        new versions from the libtool 1.5 distribution (the last one is a copy of
1073        a file called libtool.m4). This seems to have fixed the need to patch
1074        "configure" to support Darwin 1.3 (which I used to do). However, I still
1075        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1076        workstation).
1078    24. Changed the PCRE licence to be the more standard "BSD" licence.
1081    Version 4.5 01-Dec-03
1082    ---------------------
1084     1. There has been some re-arrangement of the code for the match() function so
1085        that it can be compiled in a version that does not call itself recursively.
1086        Instead, it keeps those local variables that need separate instances for
1087        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1088        needs to "recurse". Keeping track of where control must go is done by means
1089        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1090        hide most of the details from the main code, and operates only if
1091        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1092        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1093        operating.
1095        To make it easier for callers to provide specially tailored get/free
1096        functions for this usage, two new functions, pcre_stack_malloc, and
1097        pcre_stack_free, are used. They are always called in strict stacking order,
1098        and the size of block requested is always the same.
1100        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1101        PCRE has been compiled to use the stack or the heap for recursion. The
1102        -C option of pcretest uses this to show which version is compiled.
1104        A new data escape \S, is added to pcretest; it causes the amounts of store
1105        obtained and freed by both kinds of malloc/free at match time to be added
1106        to the output.
1108     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1109        what's available on my current Linux desktop machine.
1111     3. When matching a UTF-8 string, the test for a valid string at the start has
1112        been extended. If start_offset is not zero, PCRE now checks that it points
1113        to a byte that is the start of a UTF-8 character. If not, it returns
1114        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1115        this is necessary because there may be backward assertions in the pattern.
1116        When matching the same subject several times, it may save resources to use
1117        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1119     4. The code for checking the validity of UTF-8 strings has been tightened so
1120        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1121        containing "overlong sequences".
1123     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1124        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1125        should have been "&", but it just so happened that all the cases this let
1126        through by mistake were picked up later in the function.
1128     6. I had used a variable called "isblank" - this is a C99 function, causing
1129        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1131     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1132        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1133        so the version is shown; (c) stop "make test" echoing "./RunTest".
1135     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1137     9. The prototype for memmove() for systems that don't have it was using
1138        size_t, but the inclusion of the header that defines size_t was later. I've
1139        moved the #includes for the C headers earlier to avoid this.
1141    10. Added some adjustments to the code to make it easier to compiler on certain
1142        special systems:
1144          (a) Some "const" qualifiers were missing.
1145          (b) Added the macro EXPORT before all exported functions; by default this
1146              is defined to be empty.
1147          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1148              that it reads its output file name as an argument instead of writing
1149              to the standard output and assuming this can be redirected.
1151    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1152        class containing characters with values greater than 255, PCRE compilation
1153        went into a loop.
1155    12. A recursive reference to a subpattern that was within another subpattern
1156        that had a minimum quantifier of zero caused PCRE to crash. For example,
1157        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1158        recursion. If the recursively-called subpattern itself had a zero repeat,
1159        that was OK.
1161    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1162        buffer into which it was copied (for escape processing) was still set at
1163        1024, so long lines caused crashes.
1165    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1166        "internal error: code overflow...". This applied to any character class
1167        that was followed by a possessive quantifier.
1169    15. Modified the Makefile to add libpcre.la as a prerequisite for
1170        libpcreposix.la because I was told this is needed for a parallel build to
1171        work.
1173    16. If a pattern that contained .* following optional items at the start was
1174        studied, the wrong optimizing data was generated, leading to matching
1175        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1176        matching string must start with a or b or c. The correct conclusion for
1177        this pattern is that a match can start with any character.
1180    Version 4.4 13-Aug-03
1181    ---------------------
1183     1. In UTF-8 mode, a character class containing characters with values between
1184        127 and 255 was not handled correctly if the compiled pattern was studied.
1185        In fixing this, I have also improved the studying algorithm for such
1186        classes (slightly).
1188     2. Three internal functions had redundant arguments passed to them. Removal
1189        might give a very teeny performance improvement.
1191     3. Documentation bug: the value of the capture_top field in a callout is *one
1192        more than* the number of the hightest numbered captured substring.
1194     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1195        in incorrectly linking with a previously installed version. They now link
1196        explicitly with libpcre.la.
1198     5. configure.in no longer needs to recognize Cygwin specially.
1200     6. A problem in pcre.in for Windows platforms is fixed.
1202     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1203        pcretest, it used to include the size of the study block as part of its
1204        output. Unfortunately, the structure contains a field that has a different
1205        size on different hardware architectures. This meant that the tests that
1206        showed this size failed. As the block is currently always of a fixed size,
1207        this information isn't actually particularly useful in pcretest output, so
1208        I have just removed it.
1210     8. Three pre-processor statements accidentally did not start in column 1.
1211        Sadly, there are *still* compilers around that complain, even though
1212        standard C has not required this for well over a decade. Sigh.
1214     9. In pcretest, the code for checking callouts passed small integers in the
1215        callout_data field, which is a void * field. However, some picky compilers
1216        complained about the casts involved for this on 64-bit systems. Now
1217        pcretest passes the address of the small integer instead, which should get
1218        rid of the warnings.
1220    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1221        both compile and run time, and gives an error if an invalid UTF-8 sequence
1222        is found. There is a option for disabling this check in cases where the
1223        string is known to be correct and/or the maximum performance is wanted.
1225    11. In response to a bug report, I changed one line in Makefile.in from
1227            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1228        to
1229            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1231        to look similar to other lines, but I have no way of telling whether this
1232        is the right thing to do, as I do not use Windows. No doubt I'll get told
1233        if it's wrong...
1236    Version 4.3 21-May-03
1237    ---------------------
1239    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1240       Makefile.
1242    2. Some refactoring to improve the quality of the code:
1244       (i)   The utf8_table... variables are now declared "const".
1246       (ii)  The code for \cx, which used the "case flipping" table to upper case
1247             lower case letters, now just substracts 32. This is ASCII-specific,
1248             but the whole concept of \cx is ASCII-specific, so it seems
1249             reasonable.
1251       (iii) PCRE was using its character types table to recognize decimal and
1252             hexadecimal digits in the pattern. This is silly, because it handles
1253             only 0-9, a-f, and A-F, but the character types table is locale-
1254             specific, which means strange things might happen. A private
1255             table is now used for this - though it costs 256 bytes, a table is
1256             much faster than multiple explicit tests. Of course, the standard
1257             character types table is still used for matching digits in subject
1258             strings against \d.
1260       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1261             ending in _t are). So I've renamed it as ESC_tee.
1263    3. The first argument for regexec() in the POSIX wrapper should have been
1264       defined as "const".
1266    4. Changed pcretest to use malloc() for its buffers so that they can be
1267       Electric Fenced for debugging.
1269    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1270       to read one or more bytes before the start of the subject string. Often this
1271       had no effect on PCRE's behaviour, but in some circumstances it could
1272       provoke a segmentation fault.
1274    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1275       to try to read one or more bytes before the start of the subject string.
1277    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1278       UTF-8 support could misbehave in various ways if the subject string
1279       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1280       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1281       back over UTF-8 characters.)
1284    Version 4.2 14-Apr-03
1285    ---------------------
1287    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1289    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1290         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1291         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1292         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1293         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1294           and BUILD_EXEEXT
1295         Note: automatic setting of the BUILD variables is not yet working
1296         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1297           compile-time but not at link-time
1298         [LINK]: use for linking executables only
1299         make different versions for Windows and non-Windows
1300         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1301           libraries
1302         [LINK_FOR_BUILD]: new variable
1303         [OBJEXT]: use throughout
1304         [EXEEXT]: use throughout
1305         <winshared>: new target
1306         <wininstall>: new target
1307         <dftables.o>: use native compiler
1308         <dftables>: use native linker
1309         <install>: handle Windows platform correctly
1310         <clean>: ditto
1311         <check>: ditto
1312         copy DLL to top builddir before testing
1314       As part of these changes, -no-undefined was removed again. This was reported
1315       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1316       in any case.
1318    3. Some tidies to get rid of compiler warnings:
1320       . In the match_data structure, match_limit was an unsigned long int, whereas
1321         match_call_count was an int. I've made them both unsigned long ints.
1323       . In pcretest the fact that a const uschar * doesn't automatically cast to
1324         a void * provoked a warning.
1326       . Turning on some more compiler warnings threw up some "shadow" variables
1327         and a few more missing casts.
1329    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1330       option, a class that contained a single character with a value between 128
1331       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1333    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1334       option, a class that contained several characters, but with at least one
1335       whose value was between 128 and 255 caused PCRE to crash.
1338    Version 4.1 12-Mar-03
1339    ---------------------
1341    1. Compiling with gcc -pedantic found a couple of places where casts were
1342    needed, and a string in dftables.c that was longer than standard compilers are
1343    required to support.
1345    2. Compiling with Sun's compiler found a few more places where the code could
1346    be tidied up in order to avoid warnings.
1348    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1349    first of these names is deprecated in the latest Autoconf in favour of the name
1350    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1351    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1352    analogy I have changed it to CFLAGS_FOR_BUILD.
1354    4. Added -no-undefined to the linking command in the Makefile, because this is
1355    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1356    linking step for the pcreposix library.
1358    5. PCRE was failing to diagnose the case of two named groups with the same
1359    name.
1361    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1362    literal character that is needed in the subject for a match, and scans along to
1363    ensure that it is present before embarking on the full matching process. This
1364    saves time in cases of nested unlimited repeats that are never going to match.
1365    Problem: the scan can take a lot of time if the subject is very long (e.g.
1366    megabytes), thus penalizing straightforward matches. It is now done only if the
1367    amount of subject to be scanned is less than 1000 bytes.
1369    7. A lesser problem with the same optimization is that it was recording the
1370    first character of an anchored pattern as "needed", thus provoking a search
1371    right along the subject, even when the first match of the pattern was going to
1372    fail. The "needed" character is now not set for anchored patterns, unless it
1373    follows something in the pattern that is of non-fixed length. Thus, it still
1374    fulfils its original purpose of finding quick non-matches in cases of nested
1375    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1378    Version 4.0 17-Feb-03
1379    ---------------------
1381    1. If a comment in an extended regex that started immediately after a meta-item
1382    extended to the end of string, PCRE compiled incorrect data. This could lead to
1383    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1385    2. Moved to autoconf 2.53 and libtool 1.4.2.
1387    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1388    the special perltest8 script is no longer needed - all the tests can be run
1389    from a single perltest script.
1391    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1392    by \s. It has now been removed in PCRE. This means it isn't recognized as
1393    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1394    class [:space:] *does* include VT, thereby creating a mess.
1396    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1397    space and tab.
1399    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1400    its new features into the main test script, reducing the number of scripts.
1402    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1403    were backward compatible, and made the (?i) apply to the whole pattern, as if
1404    /i were given. Now it behaves more logically, and applies the option setting
1405    only to what follows. PCRE has been changed to follow suit. However, if it
1406    finds options settings right at the start of the pattern, it extracts them into
1407    the global options, as before. Thus, they show up in the info data.
1409    8. Added support for the \Q...\E escape sequence. Characters in between are
1410    treated as literals. This is slightly different from Perl in that $ and @ are
1411    also handled as literals inside the quotes. In Perl, they will cause variable
1412    interpolation. Note the following examples:
1414        Pattern            PCRE matches      Perl matches
1416        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
1417        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
1418        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
1420    For compatibility with Perl, \Q...\E sequences are recognized inside character
1421    classes as well as outside them.
1423    9. Re-organized 3 code statements in pcretest to avoid "overflow in
1424    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1425    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1426    signed/unsigned warnings.
1428    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1429    option for pcretest, so I've replaced it by a simple function that does just
1430    that job.
1432    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1433    "pcregrep -".
1435    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1436    Java package. This provides some syntactic sugar for simple cases of what my
1437    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1438    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1439    item, you can use this simplified notation. Note that only makes sense with
1440    greedy quantifiers. Consequently, the use of the possessive quantifier forces
1441    greediness, whatever the setting of the PCRE_UNGREEDY option.
1443    13. A change of greediness default within a pattern was not taking effect at
1444    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1445    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1446    was abstracted outside.
1448    14. PCRE now supports the \G assertion. It is true when the current matching
1449    position is at the start point of the match. This differs from \A when the
1450    starting offset is non-zero. Used with the /g option of pcretest (or similar
1451    code), it works in the same way as it does for Perl's /g option. If all
1452    alternatives of a regex begin with \G, the expression is anchored to the start
1453    match position, and the "anchored" flag is set in the compiled expression.
1455    15. Some bugs concerning the handling of certain option changes within patterns
1456    have been fixed. These applied to options other than (?ims). For example,
1457    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1458    been the other way round. Some of this was related to change 7 above.
1460    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1461    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1462    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1463    POSIX classes only within a class (e.g. /[[:alpha:]]/).
1465    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1466    mode. Unlike ".", it always matches newline, whatever the setting of
1467    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1468    assertions. Perl allows it, but it doesn't (in general) work because it can't
1469    calculate the length of the lookbehind. At least, that's the case for Perl
1470    5.8.0 - I've been told they are going to document that it doesn't work in
1471    future.
1473    18. Added an error diagnosis for escapes that PCRE does not support: these are
1474    \L, \l, \N, \P, \p, \U, \u, and \X.
1476    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1477    reading past the end of the pattern in cases such as /[abcd/.
1479    20. PCRE was getting more memory than necessary for patterns with classes that
1480    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1482    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1483    compiling PCRE for use with Virtual Pascal.
1485    22. Small fix to the Makefile to make it work properly if the build is done
1486    outside the source tree.
1488    23. Added a new extension: a condition to go with recursion. If a conditional
1489    subpattern starts with (?(R) the "true" branch is used if recursion has
1490    happened, whereas the "false" branch is used only at the top level.
1492    24. When there was a very long string of literal characters (over 255 bytes
1493    without UTF support, over 250 bytes with UTF support), the computation of how
1494    much memory was required could be incorrect, leading to segfaults or other
1495    strange effects.
1497    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1498    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1499    there was a subsequent back reference to those brackets. This meant that, for
1500    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1501    possible to check for precisely this case. All we can do is abandon the
1502    optimization if .* occurs inside capturing brackets when there are any back
1503    references whatsoever. (See below for a better fix that came later.)
1505    26. The handling of the optimization for finding the first character of a
1506    non-anchored pattern, and for finding a character that is required later in the
1507    match were failing in some cases. This didn't break the matching; it just
1508    failed to optimize when it could. The way this is done has been re-implemented.
1510    27. Fixed typo in error message for invalid (?R item (it said "(?p").
1512    28. Added a new feature that provides some of the functionality that Perl
1513    provides with (?{...}). The facility is termed a "callout". The way it is done
1514    in PCRE is for the caller to provide an optional function, by setting
1515    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1516    global variable. By default it is unset, which disables all calling out. To get
1517    the function called, the regex must include (?C) at appropriate points. This
1518    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1519    This provides a means of identifying different callout points. When PCRE
1520    reaches such a point in the regex, if pcre_callout has been set, the external
1521    function is called. It is provided with data in a structure called
1522    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1523    matching continues; if it returns a non-zero value, the match at the current
1524    point fails. However, backtracking will occur if possible. [This was changed
1525    later and other features added - see item 49 below.]
1527    29. pcretest is upgraded to test the callout functionality. It provides a
1528    callout function that displays information. By default, it shows the start of
1529    the match and the current position in the text. There are some new data escapes
1530    to vary what happens:
1532        \C+         in addition, show current contents of captured substrings
1533        \C-         do not supply a callout function
1534        \C!n        return 1 when callout number n is reached
1535        \C!n!m      return 1 when callout number n is reached for the mth time
1537    30. If pcregrep was called with the -l option and just a single file name, it
1538    output "<stdin>" if a match was found, instead of the file name.
1540    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1541    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1542    pcre_exec(). This saves a malloc/free per call. The default value of
1543    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1544    when configuring.
1546    32. The default maximum size of a compiled pattern is 64K. There have been a
1547    few cases of people hitting this limit. The code now uses macros to handle the
1548    storing of links as offsets within the compiled pattern. It defaults to 2-byte
1549    links, but this can be changed to 3 or 4 bytes by --with-link-size when
1550    configuring. Tests 2 and 5 work only with 2-byte links because they output
1551    debugging information about compiled patterns.
1553    33. Internal code re-arrangements:
1555    (a) Moved the debugging function for printing out a compiled regex into
1556        its own source file (printint.c) and used #include to pull it into
1557        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1558        separate copies.
1560    (b) Defined the list of op-code names for debugging as a macro in
1561        internal.h so that it is next to the definition of the opcodes.
1563    (c) Defined a table of op-code lengths for simpler skipping along compiled
1564        code. This is again a macro in internal.h so that it is next to the
1565        definition of the opcodes.
1567    34. Added support for recursive calls to individual subpatterns, along the
1568    lines of Robin Houston's patch (but implemented somewhat differently).
1570    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1571    allow it to read and process whole directories in Win32. This code was
1572    contributed by Lionel Fourquaux; it has not been tested by me.
1574    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1575    used to name a group. Names consist of alphanumerics and underscores, and must
1576    be unique. Back references use the syntax (?P=name) and recursive calls use
1577    (?P>name) which is a PCRE extension to the Python extension. Groups still have
1578    numbers. The function pcre_fullinfo() can be used after compilation to extract
1579    a name/number map. There are three relevant calls:
1581      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
1582      PCRE_INFO_NAMECOUNT            yields the number of entries
1583      PCRE_INFO_NAMETABLE            yields a pointer to the map.
1585    The map is a vector of fixed-size entries. The size of each entry depends on
1586    the length of the longest name used. The first two bytes of each entry are the
1587    group number, most significant byte first. There follows the corresponding
1588    name, zero terminated. The names are in alphabetical order.
1590    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1591    case instead of 255. Making it the same both with and without UTF-8 support
1592    means that the same test output works with both.
1594    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1595    calling malloc() with a zero argument.
1597    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1598    optimization. I've improved things by keeping a bitmap of backreferences with
1599    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1600    fact referenced, the optimization can be applied. It is unlikely that a
1601    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1602    the match to follow \n) will appear inside brackets with a number greater than
1603    31, but if it does, any back reference > 31 suppresses the optimization.
1605    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1606    of disabling numbered capturing parentheses. Any opening parenthesis that is
1607    not followed by ? behaves as if it were followed by ?: but named parentheses
1608    can still be used for capturing (and they will acquire numbers in the usual
1609    way).
1611    41. Redesigned the return codes from the match() function into yes/no/error so
1612    that errors can be passed back from deep inside the nested calls. A malloc
1613    failure while inside a recursive subpattern call now causes the
1614    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1616    42. It is now possible to set a limit on the number of times the match()
1617    function is called in a call to pcre_exec(). This facility makes it possible to
1618    limit the amount of recursion and backtracking, though not in a directly
1619    obvious way, because the match() function is used in a number of different
1620    circumstances. The count starts from zero for each position in the subject
1621    string (for non-anchored patterns). The default limit is, for compatibility, a
1622    large number, namely 10 000 000. You can change this in two ways:
1624    (a) When configuring PCRE before making, you can use --with-match-limit=n
1625        to set a default value for the compiled library.
1627    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1628        a different value is set. See 45 below.
1630    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1632    43. Added a new function pcre_config(int, void *) to enable run-time extraction
1633    of things that can be changed at compile time. The first argument specifies
1634    what is wanted and the second points to where the information is to be placed.
1635    The current list of available information is:
1637      PCRE_CONFIG_UTF8
1639    The output is an integer that is set to one if UTF-8 support is available;
1640    otherwise it is set to zero.
1644    The output is an integer that it set to the value of the code that is used for
1645    newline. It is either LF (10) or CR (13).
1649    The output is an integer that contains the number of bytes used for internal
1650    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
1654    The output is an integer that contains the threshold above which the POSIX
1655    interface uses malloc() for output vectors. See item 31 above.
1659    The output is an unsigned integer that contains the default limit of the number
1660    of match() calls in a pcre_exec() execution. See 42 above.
1662    44. pcretest has been upgraded by the addition of the -C option. This causes it
1663    to extract all the available output from the new pcre_config() function, and to
1664    output it. The program then exits immediately.
1666    45. A need has arisen to pass over additional data with calls to pcre_exec() in
1667    order to support additional features. One way would have been to define
1668    pcre_exec2() (for example) with extra arguments, but this would not have been
1669    extensible, and would also have required all calls to the original function to
1670    be mapped to the new one. Instead, I have chosen to extend the mechanism that
1671    is used for passing in "extra" data from pcre_study().
1673    The pcre_extra structure is now exposed and defined in pcre.h. It currently
1674    contains the following fields:
1676      flags         a bitmap indicating which of the following fields are set
1677      study_data    opaque data from pcre_study()
1678      match_limit   a way of specifying a limit on match() calls for a specific
1679                      call to pcre_exec()
1680      callout_data  data for callouts (see 49 below)
1682    The flag bits are also defined in pcre.h, and are
1688    The pcre_study() function now returns one of these new pcre_extra blocks, with
1689    the actual study data pointed to by the study_data field, and the
1690    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
1691    before. That is, this change is entirely upwards-compatible and requires no
1692    change to existing code.
1694    If you want to pass in additional data to pcre_exec(), you can either place it
1695    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
1696    block.
1698    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
1699    data string contains the escape sequence \M, pcretest calls pcre_exec() several
1700    times with different match limits, until it finds the minimum value needed for
1701    pcre_exec() to complete. The value is then output. This can be instructive; for
1702    most simple matches the number is quite small, but for pathological cases it
1703    gets very large very quickly.
1705    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
1706    returns the size of the data block pointed to by the study_data field in a
1707    pcre_extra block, that is, the value that was passed as the argument to
1708    pcre_malloc() when PCRE was getting memory in which to place the information
1709    created by pcre_study(). The fourth argument should point to a size_t variable.
1710    pcretest has been extended so that this information is shown after a successful
1711    pcre_study() call when information about the compiled regex is being displayed.
1713    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
1714    because what follows is always an absolute path. (Later: it turns out that this
1715    is more than cosmetic for MinGW, because it doesn't like empty path
1716    components.)
1718    49. Some changes have been made to the callout feature (see 28 above):
1720    (i)  A callout function now has three choices for what it returns:
1722           0  =>  success, carry on matching
1723         > 0  =>  failure at this point, but backtrack if possible
1724         < 0  =>  serious error, return this value from pcre_exec()
1726         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
1727         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
1728         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
1729         use by callout functions. It will never be used by PCRE itself.
1731    (ii) The pcre_extra structure (see 45 above) has a void * field called
1732         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
1733         pcre_callout_block structure has a field of the same name. The contents of
1734         the field passed in the pcre_extra structure are passed to the callout
1735         function in the corresponding field in the callout block. This makes it
1736         easier to use the same callout-containing regex from multiple threads. For
1737         testing, the pcretest program has a new data escape
1739           \C*n        pass the number n (may be negative) as callout_data
1741         If the callout function in pcretest receives a non-zero value as
1742         callout_data, it returns that value.
1744    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
1745    there were some redundant $(CFLAGS) in commands that are now specified as
1746    $(LINK), which already includes $(CFLAGS).
1748    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
1749    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
1750    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
1751    one-byte characters throughout. Note that case-insensitive matching applies
1752    only to characters whose values are less than 256. PCRE doesn't support the
1753    notion of cases for higher-valued characters.
1755    (i)   A character class whose characters are all within 0-255 is handled as
1756          a bit map, and the map is inverted for negative classes. Previously, a
1757          character > 255 always failed to match such a class; however it should
1758          match if the class was a negative one (e.g. [^ab]). This has been fixed.
1760    (ii)  A negated character class with a single character < 255 is coded as
1761          "not this character" (OP_NOT). This wasn't working properly when the test
1762          character was multibyte, either singly or repeated.
1764    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
1765          mode, for example: \x{100}{2,3}.
1767    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
1768          singly or repeated) now correctly test multibyte characters. However,
1769          PCRE doesn't recognize any characters with values greater than 255 as
1770          digits, spaces, or word characters. Such characters always match \D, \S,
1771          and \W, and never match \d, \s, or \w.
1773    (v)   Classes may now contain characters and character ranges with values
1774          greater than 255. For example: [ab\x{100}-\x{400}].
1776    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
1777          PCRE in UTF-8 mode.
1779    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
1780    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
1781    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
1782    value.)
1784    53. The single man page has become too large. I have therefore split it up into
1785    a number of separate man pages. These also give rise to individual HTML pages;
1786    these are now put in a separate directory, and there is an index.html page that
1787    lists them all. Some hyperlinking between the pages has been installed.
1789    54. Added convenience functions for handling named capturing parentheses.
1791    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
1792    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
1793    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
1794    are faulted.
1796    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
1797    calling configure. These values are used when compiling the dftables.c program
1798    which is run to generate the source of the default character tables. They
1799    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
1800    you will need to set these values.
1802    57. Updated the building process for Windows DLL, as provided by Fred Cox.
1805    Version 3.9 02-Jan-02
1806    ---------------------
1808    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
1810    2. If --disable-static was given, the building process failed when trying to
1811    build pcretest and pcregrep. (For some reason it was using libtool to compile
1812    them, which is not right, as they aren't part of the library.)
1815    Version 3.8 18-Dec-01
1816    ---------------------
1818    1. The experimental UTF-8 code was completely screwed up. It was packing the
1819    bytes in the wrong order. How dumb can you get?
1822    Version 3.7 29-Oct-01
1823    ---------------------
1825    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
1826    This caused pcretest, when used on the test data, to segfault. Unfortunately,
1827    this didn't happen under Solaris 8, where I normally test things.
1829    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
1830    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
1831    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
1832    this fix an hour or so after the initial 3.7 release.)
1835    Version 3.6 23-Oct-01
1836    ---------------------
1838    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
1839    offsets passed as NULL with zero offset count.
1841    2. The config.guess and config.sub files had not been updated when I moved to
1842    the latest autoconf.
1845    Version 3.5 15-Aug-01
1846    ---------------------
1848    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
1849    had been forgotten.
1851    2. By using declared but undefined structures, we can avoid using "void"
1852    definitions in pcre.h while keeping the internal definitions of the structures
1853    private.
1855    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
1856    user point of view, this means that both static and shared libraries are built
1857    by default, but this can be individually controlled. More of the work of
1858    handling this static/shared cases is now inside libtool instead of PCRE's make
1859    file.
1861    4. The pcretest utility is now installed along with pcregrep because it is
1862    useful for users (to test regexs) and by doing this, it automatically gets
1863    relinked by libtool. The documentation has been turned into a man page, so
1864    there are now .1, .txt, and .html versions in /doc.
1866    5. Upgrades to pcregrep:
1867       (i)   Added long-form option names like gnu grep.
1868       (ii)  Added --help to list all options with an explanatory phrase.
1869       (iii) Added -r, --recursive to recurse into sub-directories.
1870       (iv)  Added -f, --file to read patterns from a file.
1872    6. pcre_exec() was referring to its "code" argument before testing that
1873    argument for NULL (and giving an error if it was NULL).
1875    7. Upgraded Makefile.in to allow for compiling in a different directory from
1876    the source directory.
1878    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
1879    options bits, the pointer it was passed was to an int instead of to an unsigned
1880    long int. This mattered only on 64-bit systems.
1882    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
1883    generated) instead of pcre.in, which it its source. Also made the same change
1884    in several of the .c files.
1886    10. A new release of gcc defines printf() as a macro, which broke pcretest
1887    because it had an ifdef in the middle of a string argument for printf(). Fixed
1888    by using separate calls to printf().
1890    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
1891    script, to force use of CR or LF instead of \n in the source. On non-Unix
1892    systems, the value can be set in config.h.
1894    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
1895    absolute limit. Changed the text of the error message to make this clear, and
1896    likewise updated the man page.
1898    13. The limit of 99 on the number of capturing subpatterns has been removed.
1899    The new limit is 65535, which I hope will not be a "real" limit.
1902    Version 3.4 22-Aug-00
1903    ---------------------
1905    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
1907    2. Diagnose condition (?(0) as an error instead of crashing on matching.
1910  Version 3.3 01-Aug-00  Version 3.3 01-Aug-00
1911  ---------------------  ---------------------

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