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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 7.1 05-Mar-07
5    ---------------------
6    
7     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
8        that is more "standard", making use of automake and other autotools.
9    
10    
11    Version 7.0 19-Dec-06
12    ---------------------
13    
14     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
15        moving to gcc 4.1.1.
16    
17     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
18        sys/time.h, which is documented as needed for this function. It doesn't
19        seem to matter on Linux, but it showed up on some releases of OS X.
20    
21     3. It seems that there are systems where bytes whose values are greater than
22        127 match isprint() in the "C" locale. The "C" locale should be the
23        default when a C program starts up. In most systems, only ASCII printing
24        characters match isprint(). This difference caused the output from pcretest
25        to vary, making some of the tests fail. I have changed pcretest so that:
26    
27        (a) When it is outputting text in the compiled version of a pattern, bytes
28            other than 32-126 are always shown as hex escapes.
29    
30        (b) When it is outputting text that is a matched part of a subject string,
31            it does the same, unless a different locale has been set for the match
32            (using the /L modifier). In this case, it uses isprint() to decide.
33    
34     4. Fixed a major bug that caused incorrect computation of the amount of memory
35        required for a compiled pattern when options that changed within the
36        pattern affected the logic of the preliminary scan that determines the
37        length. The relevant options are -x, and -i in UTF-8 mode. The result was
38        that the computed length was too small. The symptoms of this bug were
39        either the PCRE error "internal error: code overflow" from pcre_compile(),
40        or a glibc crash with a message such as "pcretest: free(): invalid next
41        size (fast)". Examples of patterns that provoked this bug (shown in
42        pcretest format) are:
43    
44          /(?-x: )/x
45          /(?x)(?-x: \s*#\s*)/
46          /((?i)[\x{c0}])/8
47          /(?i:[\x{c0}])/8
48    
49        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
50        is now done differently.
51    
52     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
53        wrapper classes; (b) implement a new function in the C++ scanner that is
54        more efficient than the old way of doing things because it avoids levels of
55        recursion in the regex matching; (c) add a paragraph to the documentation
56        for the FullMatch() function.
57    
58     6. The escape sequence \n was being treated as whatever was defined as
59        "newline". Not only was this contrary to the documentation, which states
60        that \n is character 10 (hex 0A), but it also went horribly wrong when
61        "newline" was defined as CRLF. This has been fixed.
62    
63     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
64        was being set to -1 for the "end of line" case (supposedly a value that no
65        character can have). Though this value is never used (the check for end of
66        line is "zero bytes in current character"), it caused compiler complaints.
67        I've changed it to 0xffffffff.
68    
69     8. In pcre_version.c, the version string was being built by a sequence of
70        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
71        string (as it is for production releases) called a macro with an empty
72        argument. The C standard says the result of this is undefined. The gcc
73        compiler treats it as an empty string (which was what was wanted) but it is
74        reported that Visual C gives an error. The source has been hacked around to
75        avoid this problem.
76    
77     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
78        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
79        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
80        of them did).
81    
82    10. Originally, pcretest opened its input and output without "b"; then I was
83        told that "b" was needed in some environments, so it was added for release
84        5.0 to both the input and output. (It makes no difference on Unix-like
85        systems.) Later I was told that it is wrong for the input on Windows. I've
86        now abstracted the modes into two macros, to make it easier to fiddle with
87        them, and removed "b" from the input mode under Windows.
88    
89    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
90    
91    12. Added -help and --help to pcretest as an official way of being reminded
92        of the options.
93    
94    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
95        and pcrecpp.cc because they annoy compilers at high warning levels.
96    
97    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
98    
99    15. Fixed an occurrence of == in configure.ac that should have been = (shell
100        scripts are not C programs :-) and which was not noticed because it works
101        on Linux.
102    
103    16. pcretest is supposed to handle any length of pattern and data line (as one
104        line or as a continued sequence of lines) by extending its input buffer if
105        necessary. This feature was broken for very long pattern lines, leading to
106        a string of junk being passed to pcre_compile() if the pattern was longer
107        than about 50K.
108    
109    17. I have done a major re-factoring of the way pcre_compile() computes the
110        amount of memory needed for a compiled pattern. Previously, there was code
111        that made a preliminary scan of the pattern in order to do this. That was
112        OK when PCRE was new, but as the facilities have expanded, it has become
113        harder and harder to keep it in step with the real compile phase, and there
114        have been a number of bugs (see for example, 4 above). I have now found a
115        cunning way of running the real compile function in a "fake" mode that
116        enables it to compute how much memory it would need, while actually only
117        ever using a few hundred bytes of working memory and without too many
118        tests of the mode. This should make future maintenance and development
119        easier. A side effect of this work is that the limit of 200 on the nesting
120        depth of parentheses has been removed (though this was never a serious
121        limitation, I suspect). However, there is a downside: pcre_compile() now
122        runs more slowly than before (30% or more, depending on the pattern). I
123        hope this isn't a big issue. There is no effect on runtime performance.
124    
125    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
126        newline (only possible for the last line of a file) and it was a
127        pattern that set a locale (followed by /Lsomething), pcretest crashed.
128    
129    19. Added additional timing features to pcretest. (1) The -tm option now times
130        matching only, not compiling. (2) Both -t and -tm can be followed, as a
131        separate command line item, by a number that specifies the number of
132        repeats to use when timing. The default is 50000; this gives better
133        precision, but takes uncomfortably long for very large patterns.
134    
135    20. Extended pcre_study() to be more clever in cases where a branch of a
136        subpattern has no definite first character. For example, (a*|b*)[cd] would
137        previously give no result from pcre_study(). Now it recognizes that the
138        first character must be a, b, c, or d.
139    
140    21. There was an incorrect error "recursive call could loop indefinitely" if
141        a subpattern (or the entire pattern) that was being tested for matching an
142        empty string contained only one non-empty item after a nested subpattern.
143        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
144        incorrectly, because the \d was being skipped in the check.
145    
146    22. The pcretest program now has a new pattern option /B and a command line
147        option -b, which is equivalent to adding /B to every pattern. This causes
148        it to show the compiled bytecode, without the additional information that
149        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
150        is the same as /B/I).
151    
152    23. A new optimization is now able automatically to treat some sequences such
153        as a*b as a*+b. More specifically, if something simple (such as a character
154        or a simple class like \d) has an unlimited quantifier, and is followed by
155        something that cannot possibly match the quantified thing, the quantifier
156        is automatically "possessified".
157    
158    24. A recursive reference to a subpattern whose number was greater than 39
159        went wrong under certain circumstances in UTF-8 mode. This bug could also
160        have affected the operation of pcre_study().
161    
162    25. Realized that a little bit of performance could be had by replacing
163        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
164    
165    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
166    
167    27. Possessive quantifiers such as a++ were previously implemented by turning
168        them into atomic groups such as ($>a+). Now they have their own opcodes,
169        which improves performance. This includes the automatically created ones
170        from 23 above.
171    
172    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
173        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
174        the first matched character to be a colon. This applied both to named and
175        numbered groups.
176    
177    29. The ucpinternal.h header file was missing its idempotency #ifdef.
178    
179    30. I was sent a "project" file called libpcre.a.dev which I understand makes
180        building PCRE on Windows easier, so I have included it in the distribution.
181    
182    31. There is now a check in pcretest against a ridiculously large number being
183        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
184        loop, the loop is abandoned.
185    
186    32. Forward references to subpatterns in conditions such as (?(2)...) where
187        subpattern 2 is defined later cause pcre_compile() to search forwards in
188        the pattern for the relevant set of parentheses. This search went wrong
189        when there were unescaped parentheses in a character class, parentheses
190        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
191    
192    33. "Subroutine" calls and backreferences were previously restricted to
193        referencing subpatterns earlier in the regex. This restriction has now
194        been removed.
195    
196    34. Added a number of extra features that are going to be in Perl 5.10. On the
197        whole, these are just syntactic alternatives for features that PCRE had
198        previously implemented using the Python syntax or my own invention. The
199        other formats are all retained for compatibility.
200    
201        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
202            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
203            also .NET compatible.
204    
205        (b) A recursion or subroutine call to a named group can now be defined as
206            (?&name) as well as (?P>name).
207    
208        (c) A backreference to a named group can now be defined as \k<name> or
209            \k'name' as well as (?P=name). The new forms, as well as being in Perl
210            5.10, are also .NET compatible.
211    
212        (d) A conditional reference to a named group can now use the syntax
213            (?(<name>) or (?('name') as well as (?(name).
214    
215        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
216            groups (named and numbered) that are never evaluated inline, but can be
217            called as "subroutines" from elsewhere. In effect, the DEFINE condition
218            is always false. There may be only one alternative in such a group.
219    
220        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
221            as the simple (?(R). The condition is true only if the most recent
222            recursion is that of the given number or name. It does not search out
223            through the entire recursion stack.
224    
225        (g) The escape \gN or \g{N} has been added, where N is a positive or
226            negative number, specifying an absolute or relative reference.
227    
228    35. Tidied to get rid of some further signed/unsigned compiler warnings and
229        some "unreachable code" warnings.
230    
231    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
232        things, this adds five new scripts.
233    
234    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
235        There were also incompatibilities regarding the handling of \Q..\E inside
236        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
237        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
238    
239    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
240        matches an empty string, and forcibly breaks the loop. There were bugs in
241        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
242        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
243        separate and independent bugs (that affected different cases) have been
244        fixed.
245    
246    39. Refactored the code to abolish the use of different opcodes for small
247        capturing bracket numbers. This is a tidy that I avoided doing when I
248        removed the limit on the number of capturing brackets for 3.5 back in 2001.
249        The new approach is not only tidier, it makes it possible to reduce the
250        memory needed to fix the previous bug (38).
251    
252    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
253        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
254        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
255        mode.
256    
257    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
258        report.
259    
260    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
261        copy construction and assignment in the C++ wrapper.
262    
263    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
264        couple of bugs that could have given wrong results in the "--newline=crlf"
265        case.
266    
267    44. Added a number of casts and did some reorganization of signed/unsigned int
268        variables following suggestions from Dair Grant. Also renamed the variable
269        "this" as "item" because it is a C++ keyword.
270    
271    45. Arranged for dftables to add
272    
273          #include "pcre_internal.h"
274    
275        to pcre_chartables.c because without it, gcc 4.x may remove the array
276        definition from the final binary if PCRE is built into a static library and
277        dead code stripping is activated.
278    
279    46. For an unanchored pattern, if a match attempt fails at the start of a
280        newline sequence, and the newline setting is CRLF or ANY, and the next two
281        characters are CRLF, advance by two characters instead of one.
282    
283    
284    Version 6.7 04-Jul-06
285    ---------------------
286    
287     1. In order to handle tests when input lines are enormously long, pcretest has
288        been re-factored so that it automatically extends its buffers when
289        necessary. The code is crude, but this _is_ just a test program. The
290        default size has been increased from 32K to 50K.
291    
292     2. The code in pcre_study() was using the value of the re argument before
293        testing it for NULL. (Of course, in any sensible call of the function, it
294        won't be NULL.)
295    
296     3. The memmove() emulation function in pcre_internal.h, which is used on
297        systems that lack both memmove() and bcopy() - that is, hardly ever -
298        was missing a "static" storage class specifier.
299    
300     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
301        containing an extended class (one that cannot be represented by a bitmap
302        because it contains high-valued characters or Unicode property items, e.g.
303        [\pZ]). Almost always one would set UTF-8 mode when processing such a
304        pattern, but PCRE should not loop if you do not (it no longer does).
305        [Detail: two cases were found: (a) a repeated subpattern containing an
306        extended class; (b) a recursive reference to a subpattern that followed a
307        previous extended class. It wasn't skipping over the extended class
308        correctly when UTF-8 mode was not set.]
309    
310     5. A negated single-character class was not being recognized as fixed-length
311        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
312        compile error "lookbehind assertion is not fixed length".
313    
314     6. The RunPerlTest auxiliary script was showing an unexpected difference
315        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
316        write a Perl script that can interpret lines of an input file either as
317        byte characters or as UTF-8, which is what "perltest" was being required to
318        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
319        can't do is switch easily at run time between having the "use utf8;" pragma
320        or not. In the end, I fudged it by using the RunPerlTest script to insert
321        "use utf8;" explicitly for the UTF-8 tests.
322    
323     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
324        the end of the subject string, contrary to the documentation and to what
325        Perl does. This was true of both matching functions. Now it matches only at
326        the start of the subject and immediately after *internal* newlines.
327    
328     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
329        a pointer to an int instead of a pointer to an unsigned long int. This
330        caused problems on 64-bit systems.
331    
332     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
333        instance of the 'standard' template library not being so standard".
334    
335    10. There was no check on the number of named subpatterns nor the maximum
336        length of a subpattern name. The product of these values is used to compute
337        the size of the memory block for a compiled pattern. By supplying a very
338        long subpattern name and a large number of named subpatterns, the size
339        computation could be caused to overflow. This is now prevented by limiting
340        the length of names to 32 characters, and the number of named subpatterns
341        to 10,000.
342    
343    11. Subpatterns that are repeated with specific counts have to be replicated in
344        the compiled pattern. The size of memory for this was computed from the
345        length of the subpattern and the repeat count. The latter is limited to
346        65535, but there was no limit on the former, meaning that integer overflow
347        could in principle occur. The compiled length of a repeated subpattern is
348        now limited to 30,000 bytes in order to prevent this.
349    
350    12. Added the optional facility to have named substrings with the same name.
351    
352    13. Added the ability to use a named substring as a condition, using the
353        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
354        are numbers (not recommended). Forward references are permitted.
355    
356    14. Added forward references in named backreferences (if you see what I mean).
357    
358    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
359        pattern could run off the end of the subject. For example, the pattern
360        "(?s)(.{1,5})"8 did this with the subject "ab".
361    
362    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
363        PCRE_CASELESS was set when matching characters that were quantified with ?
364        or *.
365    
366    17. A character class other than a single negated character that had a minimum
367        but no maximum quantifier - for example [ab]{6,} - was not handled
368        correctly by pce_dfa_exec(). It would match only one character.
369    
370    18. A valid (though odd) pattern that looked like a POSIX character
371        class but used an invalid character after [ (for example [[,abc,]]) caused
372        pcre_compile() to give the error "Failed: internal error: code overflow" or
373        in some cases to crash with a glibc free() error. This could even happen if
374        the pattern terminated after [[ but there just happened to be a sequence of
375        letters, a binary zero, and a closing ] in the memory that followed.
376    
377    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
378        over the years. Originally (before any Unicode support), just the bottom 8
379        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
380        output from "man perlunicode" includes this:
381    
382          The regular expression compiler produces polymorphic opcodes.  That
383          is, the pattern adapts to the data and automatically switches to
384          the Unicode character scheme when presented with Unicode data--or
385          instead uses a traditional byte scheme when presented with byte
386          data.
387    
388        Sadly, a wide octal escape does not cause a switch, and in a string with
389        no other multibyte characters, these octal escapes are treated as before.
390        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
391        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
392        Unicode string.
393    
394        I have not perpetrated such confusion in PCRE. Up till now, it took just
395        the bottom 8 bits, as in old Perl. I have now made octal escapes with
396        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
397        translate to the appropriate multibyte character.
398    
399    29. Applied some refactoring to reduce the number of warnings from Microsoft
400        and Borland compilers. This has included removing the fudge introduced
401        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
402        a warning about an unused variable.
403    
404    21. PCRE has not included VT (character 0x0b) in the set of whitespace
405        characters since release 4.0, because Perl (from release 5.004) does not.
406        [Or at least, is documented not to: some releases seem to be in conflict
407        with the documentation.] However, when a pattern was studied with
408        pcre_study() and all its branches started with \s, PCRE still included VT
409        as a possible starting character. Of course, this did no harm; it just
410        caused an unnecessary match attempt.
411    
412    22. Removed a now-redundant internal flag bit that recorded the fact that case
413        dependency changed within the pattern. This was once needed for "required
414        byte" processing, but is no longer used. This recovers a now-scarce options
415        bit. Also moved the least significant internal flag bit to the most-
416        significant bit of the word, which was not previously used (hangover from
417        the days when it was an int rather than a uint) to free up another bit for
418        the future.
419    
420    23. Added support for CRLF line endings as well as CR and LF. As well as the
421        default being selectable at build time, it can now be changed at runtime
422        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
423        specify that it is scanning data with non-default line endings.
424    
425    24. Changed the definition of CXXLINK to make it agree with the definition of
426        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
427    
428    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
429        recursions. This makes a big different to stack usage for some patterns.
430    
431    26. If a subpattern containing a named recursion or subroutine reference such
432        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
433        the space required for the compiled pattern went wrong and gave too small a
434        value. Depending on the environment, this could lead to "Failed: internal
435        error: code overflow at offset 49" or "glibc detected double free or
436        corruption" errors.
437    
438    27. Applied patches from Google (a) to support the new newline modes and (b) to
439        advance over multibyte UTF-8 characters in GlobalReplace.
440    
441    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
442        difference for some implementation of PCRE in some Windows version.
443    
444    29. Added some extra testing facilities to pcretest:
445    
446        \q<number>   in a data line sets the "match limit" value
447        \Q<number>   in a data line sets the "match recursion limt" value
448        -S <number>  sets the stack size, where <number> is in megabytes
449    
450        The -S option isn't available for Windows.
451    
452    
453    Version 6.6 06-Feb-06
454    ---------------------
455    
456     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
457        in pcreposix.h. I have copied the definition from pcre.h.
458    
459     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
460        because pcre.h is no longer a built file.
461    
462     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
463        not normally included in the compiled code.
464    
465    
466    Version 6.5 01-Feb-06
467    ---------------------
468    
469     1. When using the partial match feature with pcre_dfa_exec(), it was not
470        anchoring the second and subsequent partial matches at the new starting
471        point. This could lead to incorrect results. For example, with the pattern
472        /1234/, partially matching against "123" and then "a4" gave a match.
473    
474     2. Changes to pcregrep:
475    
476        (a) All non-match returns from pcre_exec() were being treated as failures
477            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
478            error message is output. Some extra information is given for the
479            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
480            probably the only errors that are likely to be caused by users (by
481            specifying a regex that has nested indefinite repeats, for instance).
482            If there are more than 20 of these errors, pcregrep is abandoned.
483    
484        (b) A binary zero was treated as data while matching, but terminated the
485            output line if it was written out. This has been fixed: binary zeroes
486            are now no different to any other data bytes.
487    
488        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
489            used to set a locale for matching. The --locale=xxxx long option has
490            been added (no short equivalent) to specify a locale explicitly on the
491            pcregrep command, overriding the environment variables.
492    
493        (d) When -B was used with -n, some line numbers in the output were one less
494            than they should have been.
495    
496        (e) Added the -o (--only-matching) option.
497    
498        (f) If -A or -C was used with -c (count only), some lines of context were
499            accidentally printed for the final match.
500    
501        (g) Added the -H (--with-filename) option.
502    
503        (h) The combination of options -rh failed to suppress file names for files
504            that were found from directory arguments.
505    
506        (i) Added the -D (--devices) and -d (--directories) options.
507    
508        (j) Added the -F (--fixed-strings) option.
509    
510        (k) Allow "-" to be used as a file name for -f as well as for a data file.
511    
512        (l) Added the --colo(u)r option.
513    
514        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
515            is not present by default.
516    
517     3. A nasty bug was discovered in the handling of recursive patterns, that is,
518        items such as (?R) or (?1), when the recursion could match a number of
519        alternatives. If it matched one of the alternatives, but subsequently,
520        outside the recursion, there was a failure, the code tried to back up into
521        the recursion. However, because of the way PCRE is implemented, this is not
522        possible, and the result was an incorrect result from the match.
523    
524        In order to prevent this happening, the specification of recursion has
525        been changed so that all such subpatterns are automatically treated as
526        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
527    
528     4. I had overlooked the fact that, in some locales, there are characters for
529        which isalpha() is true but neither isupper() nor islower() are true. In
530        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
531        and ordfeminine) are like this. This affected the treatment of \w and \W
532        when they appeared in character classes, but not when they appeared outside
533        a character class. The bit map for "word" characters is now created
534        separately from the results of isalnum() instead of just taking it from the
535        upper, lower, and digit maps. (Plus the underscore character, of course.)
536    
537     5. The above bug also affected the handling of POSIX character classes such as
538        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
539        permanent tables. Instead, the bit maps for such a class were previously
540        created as the appropriate unions of the upper, lower, and digit bitmaps.
541        Now they are created by subtraction from the [[:word:]] class, which has
542        its own bitmap.
543    
544     6. The [[:blank:]] character class matches horizontal, but not vertical space.
545        It is created by subtracting the vertical space characters (\x09, \x0a,
546        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
547        subtraction was done in the overall bitmap for a character class, meaning
548        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
549        be recognized. This bug has been fixed.
550    
551     7. Patches from the folks at Google:
552    
553          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
554          real life, but is still worth protecting against".
555    
556          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
557          regular expressions".
558    
559          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
560          have it.
561    
562          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
563          "configure" and the latter not, in order to fix a problem somebody had
564          with compiling the Arg class on HP-UX.
565    
566          (e) Improve the error-handling of the C++ wrapper a little bit.
567    
568          (f) New tests for checking recursion limiting.
569    
570     8. The pcre_memmove() function, which is used only if the environment does not
571        have a standard memmove() function (and is therefore rarely compiled),
572        contained two bugs: (a) use of int instead of size_t, and (b) it was not
573        returning a result (though PCRE never actually uses the result).
574    
575     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
576        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
577        returned instead of calling malloc() with an overflowing number that would
578        most likely cause subsequent chaos.
579    
580    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
581    
582    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
583        with this option is matched, the nmatch and pmatch options of regexec() are
584        ignored.
585    
586    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
587        provided in case anyone wants to the the POSIX interface with UTF-8
588        strings.
589    
590    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
591        C++ linking (needed for some HP-UX environments).
592    
593    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
594        (unused parameter) and in the pcre_printint() function (omitted "default"
595        switch label when the default is to do nothing).
596    
597    15. Added some code to make it possible, when PCRE is compiled as a C++
598        library, to replace subject pointers for pcre_exec() with a smart pointer
599        class, thus making it possible to process discontinuous strings.
600    
601    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
602        much the same function. They were added by different people who were trying
603        to make PCRE easy to compile on non-Unix systems. It has been suggested
604        that PCRE_EXPORT be abolished now that there is more automatic apparatus
605        for compiling on Windows systems. I have therefore replaced it with
606        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
607        defaults to "extern" for C or "extern C" for C++, which works fine on
608        Unix-like systems. It is now possible to override the value of PCRE_DATA_
609        SCOPE with something explicit in config.h. In addition:
610    
611        (a) pcreposix.h still had just "extern" instead of either of these macros;
612            I have replaced it with PCRE_DATA_SCOPE.
613    
614        (b) Functions such as _pcre_xclass(), which are internal to the library,
615            but external in the C sense, all had PCRE_EXPORT in their definitions.
616            This is apparently wrong for the Windows case, so I have removed it.
617            (It makes no difference on Unix-like systems.)
618    
619    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
620        of recursive calls to match(). This is different to MATCH_LIMIT because
621        that limits the total number of calls to match(), not all of which increase
622        the depth of recursion. Limiting the recursion depth limits the amount of
623        stack (or heap if NO_RECURSE is set) that is used. The default can be set
624        when PCRE is compiled, and changed at run time. A patch from Google adds
625        this functionality to the C++ interface.
626    
627    18. Changes to the handling of Unicode character properties:
628    
629        (a) Updated the table to Unicode 4.1.0.
630    
631        (b) Recognize characters that are not in the table as "Cn" (undefined).
632    
633        (c) I revised the way the table is implemented to a much improved format
634            which includes recognition of ranges. It now supports the ranges that
635            are defined in UnicodeData.txt, and it also amalgamates other
636            characters into ranges. This has reduced the number of entries in the
637            table from around 16,000 to around 3,000, thus reducing its size
638            considerably. I realized I did not need to use a tree structure after
639            all - a binary chop search is just as efficient. Having reduced the
640            number of entries, I extended their size from 6 bytes to 8 bytes to
641            allow for more data.
642    
643        (d) Added support for Unicode script names via properties such as \p{Han}.
644    
645    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
646        matching that character.
647    
648    20. When matching a repeated Unicode property with a minimum greater than zero,
649        (for example \pL{2,}), PCRE could look past the end of the subject if it
650        reached it while seeking the minimum number of characters. This could
651        happen only if some of the characters were more than one byte long, because
652        there is a check for at least the minimum number of bytes.
653    
654    21. Refactored the implementation of \p and \P so as to be more general, to
655        allow for more different types of property in future. This has changed the
656        compiled form incompatibly. Anybody with saved compiled patterns that use
657        \p or \P will have to recompile them.
658    
659    22. Added "Any" and "L&" to the supported property types.
660    
661    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
662        but give a compile time error if the value is greater than 0xff.
663    
664    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
665        accidentally not being installed or uninstalled.
666    
667    25. The pcre.h file was built from pcre.h.in, but the only changes that were
668        made were to insert the current release number. This seemed silly, because
669        it made things harder for people building PCRE on systems that don't run
670        "configure". I have turned pcre.h into a distributed file, no longer built
671        by "configure", with the version identification directly included. There is
672        no longer a pcre.h.in file.
673    
674        However, this change necessitated a change to the pcre-config script as
675        well. It is built from pcre-config.in, and one of the substitutions was the
676        release number. I have updated configure.ac so that ./configure now finds
677        the release number by grepping pcre.h.
678    
679    26. Added the ability to run the tests under valgrind.
680    
681    
682    Version 6.4 05-Sep-05
683    ---------------------
684    
685     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
686        "--" to be printed when multiple files were scanned, even when none of the
687        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
688        consider it to be a bug, and have restored the previous behaviour.
689    
690     2. A couple of code tidies to get rid of compiler warnings.
691    
692     3. The pcretest program used to cheat by referring to symbols in the library
693        whose names begin with _pcre_. These are internal symbols that are not
694        really supposed to be visible externally, and in some environments it is
695        possible to suppress them. The cheating is now confined to including
696        certain files from the library's source, which is a bit cleaner.
697    
698     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
699        file's purpose clearer.
700    
701     5. Reorganized pcre_ucp_findchar().
702    
703    
704    Version 6.3 15-Aug-05
705    ---------------------
706    
707     1. The file libpcre.pc.in did not have general read permission in the tarball.
708    
709     2. There were some problems when building without C++ support:
710    
711        (a) If C++ support was not built, "make install" and "make test" still
712            tried to test it.
713    
714        (b) There were problems when the value of CXX was explicitly set. Some
715            changes have been made to try to fix these, and ...
716    
717        (c) --disable-cpp can now be used to explicitly disable C++ support.
718    
719        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
720            backslash in a target when C++ was disabled. This confuses some
721            versions of "make", apparently. Using an intermediate variable solves
722            this. (Same for CPP_LOBJ.)
723    
724     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
725        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
726        necessary on certain architectures.
727    
728     4. Added a setting of -export-symbols-regex to the link command to remove
729        those symbols that are exported in the C sense, but actually are local
730        within the library, and not documented. Their names all begin with
731        "_pcre_". This is not a perfect job, because (a) we have to except some
732        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
733        available (and never for static libraries). I have made a note to try to
734        find a way round (a) in the future.
735    
736    
737    Version 6.2 01-Aug-05
738    ---------------------
739    
740     1. There was no test for integer overflow of quantifier values. A construction
741        such as {1111111111111111} would give undefined results. What is worse, if
742        a minimum quantifier for a parenthesized subpattern overflowed and became
743        negative, the calculation of the memory size went wrong. This could have
744        led to memory overwriting.
745    
746     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
747    
748     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
749        operating environments where this matters.
750    
751     4. Applied Giuseppe Maxia's patch to add additional features for controlling
752        PCRE options from within the C++ wrapper.
753    
754     5. Named capturing subpatterns were not being correctly counted when a pattern
755        was compiled. This caused two problems: (a) If there were more than 100
756        such subpatterns, the calculation of the memory needed for the whole
757        compiled pattern went wrong, leading to an overflow error. (b) Numerical
758        back references of the form \12, where the number was greater than 9, were
759        not recognized as back references, even though there were sufficient
760        previous subpatterns.
761    
762     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
763        versions of gcc, e.g. 2.95.4.
764    
765    
766    Version 6.1 21-Jun-05
767    ---------------------
768    
769     1. There was one reference to the variable "posix" in pcretest.c that was not
770        surrounded by "#if !defined NOPOSIX".
771    
772     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
773        the cross-check on the old pcre_info() function, for the benefit of the
774        cut-down version of PCRE that is currently imported into Exim.
775    
776     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
777        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
778        patterns that start (?i) but I don't think that matters. The use of (?i) is
779        just an example; this all applies to the other options as well.
780    
781     4. Since libtool seems to echo the compile commands it is issuing, the output
782        from "make" can be reduced a bit by putting "@" in front of each libtool
783        compile command.
784    
785     5. Patch from the folks at Google for configure.in to be a bit more thorough
786        in checking for a suitable C++ installation before trying to compile the
787        C++ stuff. This should fix a reported problem when a compiler was present,
788        but no suitable headers.
789    
790     6. The man pages all had just "PCRE" as their title. I have changed them to
791        be the relevant file name. I have also arranged that these names are
792        retained in the file doc/pcre.txt, which is a concatenation in text format
793        of all the man pages except the little individual ones for each function.
794    
795     7. The NON-UNIX-USE file had not been updated for the different set of source
796        files that come with release 6. I also added a few comments about the C++
797        wrapper.
798    
799    
800    Version 6.0 07-Jun-05
801    ---------------------
802    
803     1. Some minor internal re-organization to help with my DFA experiments.
804    
805     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
806        didn't matter for the library itself when fully configured, but did matter
807        when compiling without UCP support, or within Exim, where the ucp files are
808        not imported.
809    
810     3. Refactoring of the library code to split up the various functions into
811        different source modules. The addition of the new DFA matching code (see
812        below) to a single monolithic source would have made it really too
813        unwieldy, quite apart from causing all the code to be include in a
814        statically linked application, when only some functions are used. This is
815        relevant even without the DFA addition now that patterns can be compiled in
816        one application and matched in another.
817    
818        The downside of splitting up is that there have to be some external
819        functions and data tables that are used internally in different modules of
820        the library but which are not part of the API. These have all had their
821        names changed to start with "_pcre_" so that they are unlikely to clash
822        with other external names.
823    
824     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
825        a different (DFA) algorithm. Although it is slower than the original
826        function, it does have some advantages for certain types of matching
827        problem.
828    
829     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
830        including restarting after a partial match.
831    
832     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
833        defined when compiling for Windows was sent to me. I have put it into the
834        code, though I have no means of testing or verifying it.
835    
836     7. Added the pcre_refcount() auxiliary function.
837    
838     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
839        match before or at the first newline in the subject string. In pcretest,
840        the /f option on a pattern can be used to set this.
841    
842     9. A repeated \w when used in UTF-8 mode with characters greater than 256
843        would behave wrongly. This has been present in PCRE since release 4.0.
844    
845    10. A number of changes to the pcregrep command:
846    
847        (a) Refactored how -x works; insert ^(...)$ instead of setting
848            PCRE_ANCHORED and checking the length, in preparation for adding
849            something similar for -w.
850    
851        (b) Added the -w (match as a word) option.
852    
853        (c) Refactored the way lines are read and buffered so as to have more
854            than one at a time available.
855    
856        (d) Implemented a pcregrep test script.
857    
858        (e) Added the -M (multiline match) option. This allows patterns to match
859            over several lines of the subject. The buffering ensures that at least
860            8K, or the rest of the document (whichever is the shorter) is available
861            for matching (and similarly the previous 8K for lookbehind assertions).
862    
863        (f) Changed the --help output so that it now says
864    
865              -w, --word-regex(p)
866    
867            instead of two lines, one with "regex" and the other with "regexp"
868            because that confused at least one person since the short forms are the
869            same. (This required a bit of code, as the output is generated
870            automatically from a table. It wasn't just a text change.)
871    
872        (g) -- can be used to terminate pcregrep options if the next thing isn't an
873            option but starts with a hyphen. Could be a pattern or a path name
874            starting with a hyphen, for instance.
875    
876        (h) "-" can be given as a file name to represent stdin.
877    
878        (i) When file names are being printed, "(standard input)" is used for
879            the standard input, for compatibility with GNU grep. Previously
880            "<stdin>" was used.
881    
882        (j) The option --label=xxx can be used to supply a name to be used for
883            stdin when file names are being printed. There is no short form.
884    
885        (k) Re-factored the options decoding logic because we are going to add
886            two more options that take data. Such options can now be given in four
887            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
888    
889        (l) Added the -A, -B, and -C options for requesting that lines of context
890            around matches be printed.
891    
892        (m) Added the -L option to print the names of files that do not contain
893            any matching lines, that is, the complement of -l.
894    
895        (n) The return code is 2 if any file cannot be opened, but pcregrep does
896            continue to scan other files.
897    
898        (o) The -s option was incorrectly implemented. For compatibility with other
899            greps, it now suppresses the error message for a non-existent or non-
900            accessible file (but not the return code). There is a new option called
901            -q that suppresses the output of matching lines, which was what -s was
902            previously doing.
903    
904        (p) Added --include and --exclude options to specify files for inclusion
905            and exclusion when recursing.
906    
907    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
908        Hopefully, it now does.
909    
910    12. Missing cast in pcre_study().
911    
912    13. Added an "uninstall" target to the makefile.
913    
914    14. Replaced "extern" in the function prototypes in Makefile.in with
915        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
916        world, but is set differently for Windows.
917    
918    15. Added a second compiling function called pcre_compile2(). The only
919        difference is that it has an extra argument, which is a pointer to an
920        integer error code. When there is a compile-time failure, this is set
921        non-zero, in addition to the error test pointer being set to point to an
922        error message. The new argument may be NULL if no error number is required
923        (but then you may as well call pcre_compile(), which is now just a
924        wrapper). This facility is provided because some applications need a
925        numeric error indication, but it has also enabled me to tidy up the way
926        compile-time errors are handled in the POSIX wrapper.
927    
928    16. Added VPATH=.libs to the makefile; this should help when building with one
929        prefix path and installing with another. (Or so I'm told by someone who
930        knows more about this stuff than I do.)
931    
932    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
933        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
934        match everything, including newlines. This is not POSIX-compatible, but
935        somebody wanted the feature. From pcretest it can be activated by using
936        both the P and the s flags.
937    
938    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
939    
940    19. libpcre.pc was being incorrectly installed as executable.
941    
942    20. A couple of places in pcretest check for end-of-line by looking for '\n';
943        it now also looks for '\r' so that it will work unmodified on Windows.
944    
945    21. Added Google's contributed C++ wrapper to the distribution.
946    
947    22. Added some untidy missing memory free() calls in pcretest, to keep
948        Electric Fence happy when testing.
949    
950    
951    
952    Version 5.0 13-Sep-04
953    ---------------------
954    
955     1. Internal change: literal characters are no longer packed up into items
956        containing multiple characters in a single byte-string. Each character
957        is now matched using a separate opcode. However, there may be more than one
958        byte in the character in UTF-8 mode.
959    
960     2. The pcre_callout_block structure has two new fields: pattern_position and
961        next_item_length. These contain the offset in the pattern to the next match
962        item, and its length, respectively.
963    
964     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
965        insertion of callouts before each pattern item. Added the /C option to
966        pcretest to make use of this.
967    
968     4. On the advice of a Windows user, the lines
969    
970          #if defined(_WIN32) || defined(WIN32)
971          _setmode( _fileno( stdout ), 0x8000 );
972          #endif  /* defined(_WIN32) || defined(WIN32) */
973    
974        have been added to the source of pcretest. This apparently does useful
975        magic in relation to line terminators.
976    
977     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
978        for the benefit of those environments where the "b" makes a difference.
979    
980     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
981        to know about it. I have put a hack into configure.in that adds in code
982        to set GCC=yes if CC=icc. This seems to end up at a point in the
983        generated configure script that is early enough to affect the setting of
984        compiler options, which is what is needed, but I have no means of testing
985        whether it really works. (The user who reported this had patched the
986        generated configure script, which of course I cannot do.)
987    
988        LATER: After change 22 below (new libtool files), the configure script
989        seems to know about icc (and also ecc). Therefore, I have commented out
990        this hack in configure.in.
991    
992     7. Added support for pkg-config (2 patches were sent in).
993    
994     8. Negated POSIX character classes that used a combination of internal tables
995        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
996        [[:^ascii]]. Typically, they would match almost any characters. The other
997        POSIX classes were not broken in this way.
998    
999     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1000        to find the match, as PCRE was deluded into thinking that the match had to
1001        start at the start point or following a newline. The same bug applied to
1002        patterns with negative forward assertions or any backward assertions
1003        preceding ".*" at the start, unless the pattern required a fixed first
1004        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1005    
1006    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1007        starting at the last subject character, bytes beyond the end of the subject
1008        string were read.
1009    
1010    11. Renamed the variable "class" as "classbits" to make life easier for C++
1011        users. (Previously there was a macro definition, but it apparently wasn't
1012        enough.)
1013    
1014    12. Added the new field "tables" to the extra data so that tables can be passed
1015        in at exec time, or the internal tables can be re-selected. This allows
1016        a compiled regex to be saved and re-used at a later time by a different
1017        program that might have everything at different addresses.
1018    
1019    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1020        -R library as well as a -L library.
1021    
1022    14. The debugging options of pcretest (-d on the command line or D on a
1023        pattern) showed incorrect output for anything following an extended class
1024        that contained multibyte characters and which was followed by a quantifier.
1025    
1026    15. Added optional support for general category Unicode character properties
1027        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1028        support. It adds about 90K to the size of the library. The meanings of the
1029        inbuilt class escapes such as \d and \s have NOT been changed.
1030    
1031    16. Updated pcredemo.c to include calls to free() to release the memory for the
1032        compiled pattern.
1033    
1034    17. The generated file chartables.c was being created in the source directory
1035        instead of in the building directory. This caused the build to fail if the
1036        source directory was different from the building directory, and was
1037        read-only.
1038    
1039    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1040        file. No doubt somebody will tell me if they don't make sense... Also added
1041        Dan Mooney's comments about building on OpenVMS.
1042    
1043    19. Added support for partial matching via the PCRE_PARTIAL option for
1044        pcre_exec() and the \P data escape in pcretest.
1045    
1046    20. Extended pcretest with 3 new pattern features:
1047    
1048        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1049              write the compiled pattern to the file whose name is "rest-of-line".
1050              This is a straight binary dump of the data, with the saved pointer to
1051              the character tables forced to be NULL. The study data, if any, is
1052              written too. After writing, pcretest reads a new pattern.
1053    
1054        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1055              compiled pattern from the given file. There must not be any
1056              occurrences of "<" in the file name (pretty unlikely); if there are,
1057              pcretest will instead treat the initial "<" as a pattern delimiter.
1058              After reading in the pattern, pcretest goes on to read data lines as
1059              usual.
1060    
1061        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1062              and 16-bit fields in a compiled pattern, to simulate a pattern that
1063              was compiled on a host of opposite endianness.
1064    
1065    21. The pcre-exec() function can now cope with patterns that were compiled on
1066        hosts of opposite endianness, with this restriction:
1067    
1068          As for any compiled expression that is saved and used later, the tables
1069          pointer field cannot be preserved; the extra_data field in the arguments
1070          to pcre_exec() should be used to pass in a tables address if a value
1071          other than the default internal tables were used at compile time.
1072    
1073    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1074        now diagnosed as an error. Previously, most of the time, a negative number
1075        would have been treated as zero, but if in addition "ovector" was passed as
1076        NULL, a crash could occur.
1077    
1078    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1079        new versions from the libtool 1.5 distribution (the last one is a copy of
1080        a file called libtool.m4). This seems to have fixed the need to patch
1081        "configure" to support Darwin 1.3 (which I used to do). However, I still
1082        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1083        workstation).
1084    
1085    24. Changed the PCRE licence to be the more standard "BSD" licence.
1086    
1087    
1088    Version 4.5 01-Dec-03
1089    ---------------------
1090    
1091     1. There has been some re-arrangement of the code for the match() function so
1092        that it can be compiled in a version that does not call itself recursively.
1093        Instead, it keeps those local variables that need separate instances for
1094        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1095        needs to "recurse". Keeping track of where control must go is done by means
1096        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1097        hide most of the details from the main code, and operates only if
1098        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1099        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1100        operating.
1101    
1102        To make it easier for callers to provide specially tailored get/free
1103        functions for this usage, two new functions, pcre_stack_malloc, and
1104        pcre_stack_free, are used. They are always called in strict stacking order,
1105        and the size of block requested is always the same.
1106    
1107        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1108        PCRE has been compiled to use the stack or the heap for recursion. The
1109        -C option of pcretest uses this to show which version is compiled.
1110    
1111        A new data escape \S, is added to pcretest; it causes the amounts of store
1112        obtained and freed by both kinds of malloc/free at match time to be added
1113        to the output.
1114    
1115     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1116        what's available on my current Linux desktop machine.
1117    
1118     3. When matching a UTF-8 string, the test for a valid string at the start has
1119        been extended. If start_offset is not zero, PCRE now checks that it points
1120        to a byte that is the start of a UTF-8 character. If not, it returns
1121        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1122        this is necessary because there may be backward assertions in the pattern.
1123        When matching the same subject several times, it may save resources to use
1124        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1125    
1126     4. The code for checking the validity of UTF-8 strings has been tightened so
1127        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1128        containing "overlong sequences".
1129    
1130     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1131        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1132        should have been "&", but it just so happened that all the cases this let
1133        through by mistake were picked up later in the function.
1134    
1135     6. I had used a variable called "isblank" - this is a C99 function, causing
1136        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1137    
1138     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1139        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1140        so the version is shown; (c) stop "make test" echoing "./RunTest".
1141    
1142     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1143    
1144     9. The prototype for memmove() for systems that don't have it was using
1145        size_t, but the inclusion of the header that defines size_t was later. I've
1146        moved the #includes for the C headers earlier to avoid this.
1147    
1148    10. Added some adjustments to the code to make it easier to compiler on certain
1149        special systems:
1150    
1151          (a) Some "const" qualifiers were missing.
1152          (b) Added the macro EXPORT before all exported functions; by default this
1153              is defined to be empty.
1154          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1155              that it reads its output file name as an argument instead of writing
1156              to the standard output and assuming this can be redirected.
1157    
1158    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1159        class containing characters with values greater than 255, PCRE compilation
1160        went into a loop.
1161    
1162    12. A recursive reference to a subpattern that was within another subpattern
1163        that had a minimum quantifier of zero caused PCRE to crash. For example,
1164        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1165        recursion. If the recursively-called subpattern itself had a zero repeat,
1166        that was OK.
1167    
1168    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1169        buffer into which it was copied (for escape processing) was still set at
1170        1024, so long lines caused crashes.
1171    
1172    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1173        "internal error: code overflow...". This applied to any character class
1174        that was followed by a possessive quantifier.
1175    
1176    15. Modified the Makefile to add libpcre.la as a prerequisite for
1177        libpcreposix.la because I was told this is needed for a parallel build to
1178        work.
1179    
1180    16. If a pattern that contained .* following optional items at the start was
1181        studied, the wrong optimizing data was generated, leading to matching
1182        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1183        matching string must start with a or b or c. The correct conclusion for
1184        this pattern is that a match can start with any character.
1185    
1186    
1187    Version 4.4 13-Aug-03
1188    ---------------------
1189    
1190     1. In UTF-8 mode, a character class containing characters with values between
1191        127 and 255 was not handled correctly if the compiled pattern was studied.
1192        In fixing this, I have also improved the studying algorithm for such
1193        classes (slightly).
1194    
1195     2. Three internal functions had redundant arguments passed to them. Removal
1196        might give a very teeny performance improvement.
1197    
1198     3. Documentation bug: the value of the capture_top field in a callout is *one
1199        more than* the number of the hightest numbered captured substring.
1200    
1201     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1202        in incorrectly linking with a previously installed version. They now link
1203        explicitly with libpcre.la.
1204    
1205     5. configure.in no longer needs to recognize Cygwin specially.
1206    
1207     6. A problem in pcre.in for Windows platforms is fixed.
1208    
1209     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1210        pcretest, it used to include the size of the study block as part of its
1211        output. Unfortunately, the structure contains a field that has a different
1212        size on different hardware architectures. This meant that the tests that
1213        showed this size failed. As the block is currently always of a fixed size,
1214        this information isn't actually particularly useful in pcretest output, so
1215        I have just removed it.
1216    
1217     8. Three pre-processor statements accidentally did not start in column 1.
1218        Sadly, there are *still* compilers around that complain, even though
1219        standard C has not required this for well over a decade. Sigh.
1220    
1221     9. In pcretest, the code for checking callouts passed small integers in the
1222        callout_data field, which is a void * field. However, some picky compilers
1223        complained about the casts involved for this on 64-bit systems. Now
1224        pcretest passes the address of the small integer instead, which should get
1225        rid of the warnings.
1226    
1227    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1228        both compile and run time, and gives an error if an invalid UTF-8 sequence
1229        is found. There is a option for disabling this check in cases where the
1230        string is known to be correct and/or the maximum performance is wanted.
1231    
1232    11. In response to a bug report, I changed one line in Makefile.in from
1233    
1234            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1235        to
1236            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1237    
1238        to look similar to other lines, but I have no way of telling whether this
1239        is the right thing to do, as I do not use Windows. No doubt I'll get told
1240        if it's wrong...
1241    
1242    
1243    Version 4.3 21-May-03
1244    ---------------------
1245    
1246    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1247       Makefile.
1248    
1249    2. Some refactoring to improve the quality of the code:
1250    
1251       (i)   The utf8_table... variables are now declared "const".
1252    
1253       (ii)  The code for \cx, which used the "case flipping" table to upper case
1254             lower case letters, now just substracts 32. This is ASCII-specific,
1255             but the whole concept of \cx is ASCII-specific, so it seems
1256             reasonable.
1257    
1258       (iii) PCRE was using its character types table to recognize decimal and
1259             hexadecimal digits in the pattern. This is silly, because it handles
1260             only 0-9, a-f, and A-F, but the character types table is locale-
1261             specific, which means strange things might happen. A private
1262             table is now used for this - though it costs 256 bytes, a table is
1263             much faster than multiple explicit tests. Of course, the standard
1264             character types table is still used for matching digits in subject
1265             strings against \d.
1266    
1267       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1268             ending in _t are). So I've renamed it as ESC_tee.
1269    
1270    3. The first argument for regexec() in the POSIX wrapper should have been
1271       defined as "const".
1272    
1273    4. Changed pcretest to use malloc() for its buffers so that they can be
1274       Electric Fenced for debugging.
1275    
1276    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1277       to read one or more bytes before the start of the subject string. Often this
1278       had no effect on PCRE's behaviour, but in some circumstances it could
1279       provoke a segmentation fault.
1280    
1281    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1282       to try to read one or more bytes before the start of the subject string.
1283    
1284    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1285       UTF-8 support could misbehave in various ways if the subject string
1286       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1287       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1288       back over UTF-8 characters.)
1289    
1290    
1291    Version 4.2 14-Apr-03
1292    ---------------------
1293    
1294    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1295    
1296    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1297         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1298         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1299         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1300         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1301           and BUILD_EXEEXT
1302         Note: automatic setting of the BUILD variables is not yet working
1303         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1304           compile-time but not at link-time
1305         [LINK]: use for linking executables only
1306         make different versions for Windows and non-Windows
1307         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1308           libraries
1309         [LINK_FOR_BUILD]: new variable
1310         [OBJEXT]: use throughout
1311         [EXEEXT]: use throughout
1312         <winshared>: new target
1313         <wininstall>: new target
1314         <dftables.o>: use native compiler
1315         <dftables>: use native linker
1316         <install>: handle Windows platform correctly
1317         <clean>: ditto
1318         <check>: ditto
1319         copy DLL to top builddir before testing
1320    
1321       As part of these changes, -no-undefined was removed again. This was reported
1322       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1323       in any case.
1324    
1325    3. Some tidies to get rid of compiler warnings:
1326    
1327       . In the match_data structure, match_limit was an unsigned long int, whereas
1328         match_call_count was an int. I've made them both unsigned long ints.
1329    
1330       . In pcretest the fact that a const uschar * doesn't automatically cast to
1331         a void * provoked a warning.
1332    
1333       . Turning on some more compiler warnings threw up some "shadow" variables
1334         and a few more missing casts.
1335    
1336    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1337       option, a class that contained a single character with a value between 128
1338       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1339    
1340    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1341       option, a class that contained several characters, but with at least one
1342       whose value was between 128 and 255 caused PCRE to crash.
1343    
1344    
1345    Version 4.1 12-Mar-03
1346    ---------------------
1347    
1348    1. Compiling with gcc -pedantic found a couple of places where casts were
1349    needed, and a string in dftables.c that was longer than standard compilers are
1350    required to support.
1351    
1352    2. Compiling with Sun's compiler found a few more places where the code could
1353    be tidied up in order to avoid warnings.
1354    
1355    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1356    first of these names is deprecated in the latest Autoconf in favour of the name
1357    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1358    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1359    analogy I have changed it to CFLAGS_FOR_BUILD.
1360    
1361    4. Added -no-undefined to the linking command in the Makefile, because this is
1362    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1363    linking step for the pcreposix library.
1364    
1365    5. PCRE was failing to diagnose the case of two named groups with the same
1366    name.
1367    
1368    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1369    literal character that is needed in the subject for a match, and scans along to
1370    ensure that it is present before embarking on the full matching process. This
1371    saves time in cases of nested unlimited repeats that are never going to match.
1372    Problem: the scan can take a lot of time if the subject is very long (e.g.
1373    megabytes), thus penalizing straightforward matches. It is now done only if the
1374    amount of subject to be scanned is less than 1000 bytes.
1375    
1376    7. A lesser problem with the same optimization is that it was recording the
1377    first character of an anchored pattern as "needed", thus provoking a search
1378    right along the subject, even when the first match of the pattern was going to
1379    fail. The "needed" character is now not set for anchored patterns, unless it
1380    follows something in the pattern that is of non-fixed length. Thus, it still
1381    fulfils its original purpose of finding quick non-matches in cases of nested
1382    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1383    
1384    
1385    Version 4.0 17-Feb-03
1386    ---------------------
1387    
1388    1. If a comment in an extended regex that started immediately after a meta-item
1389    extended to the end of string, PCRE compiled incorrect data. This could lead to
1390    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1391    
1392    2. Moved to autoconf 2.53 and libtool 1.4.2.
1393    
1394    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1395    the special perltest8 script is no longer needed - all the tests can be run
1396    from a single perltest script.
1397    
1398    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1399    by \s. It has now been removed in PCRE. This means it isn't recognized as
1400    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1401    class [:space:] *does* include VT, thereby creating a mess.
1402    
1403    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1404    space and tab.
1405    
1406    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1407    its new features into the main test script, reducing the number of scripts.
1408    
1409    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1410    were backward compatible, and made the (?i) apply to the whole pattern, as if
1411    /i were given. Now it behaves more logically, and applies the option setting
1412    only to what follows. PCRE has been changed to follow suit. However, if it
1413    finds options settings right at the start of the pattern, it extracts them into
1414    the global options, as before. Thus, they show up in the info data.
1415    
1416    8. Added support for the \Q...\E escape sequence. Characters in between are
1417    treated as literals. This is slightly different from Perl in that $ and @ are
1418    also handled as literals inside the quotes. In Perl, they will cause variable
1419    interpolation. Note the following examples:
1420    
1421        Pattern            PCRE matches      Perl matches
1422    
1423        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
1424        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
1425        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
1426    
1427    For compatibility with Perl, \Q...\E sequences are recognized inside character
1428    classes as well as outside them.
1429    
1430    9. Re-organized 3 code statements in pcretest to avoid "overflow in
1431    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1432    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1433    signed/unsigned warnings.
1434    
1435    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1436    option for pcretest, so I've replaced it by a simple function that does just
1437    that job.
1438    
1439    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1440    "pcregrep -".
1441    
1442    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1443    Java package. This provides some syntactic sugar for simple cases of what my
1444    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1445    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1446    item, you can use this simplified notation. Note that only makes sense with
1447    greedy quantifiers. Consequently, the use of the possessive quantifier forces
1448    greediness, whatever the setting of the PCRE_UNGREEDY option.
1449    
1450    13. A change of greediness default within a pattern was not taking effect at
1451    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1452    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1453    was abstracted outside.
1454    
1455    14. PCRE now supports the \G assertion. It is true when the current matching
1456    position is at the start point of the match. This differs from \A when the
1457    starting offset is non-zero. Used with the /g option of pcretest (or similar
1458    code), it works in the same way as it does for Perl's /g option. If all
1459    alternatives of a regex begin with \G, the expression is anchored to the start
1460    match position, and the "anchored" flag is set in the compiled expression.
1461    
1462    15. Some bugs concerning the handling of certain option changes within patterns
1463    have been fixed. These applied to options other than (?ims). For example,
1464    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1465    been the other way round. Some of this was related to change 7 above.
1466    
1467    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1468    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1469    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1470    POSIX classes only within a class (e.g. /[[:alpha:]]/).
1471    
1472    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1473    mode. Unlike ".", it always matches newline, whatever the setting of
1474    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1475    assertions. Perl allows it, but it doesn't (in general) work because it can't
1476    calculate the length of the lookbehind. At least, that's the case for Perl
1477    5.8.0 - I've been told they are going to document that it doesn't work in
1478    future.
1479    
1480    18. Added an error diagnosis for escapes that PCRE does not support: these are
1481    \L, \l, \N, \P, \p, \U, \u, and \X.
1482    
1483    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1484    reading past the end of the pattern in cases such as /[abcd/.
1485    
1486    20. PCRE was getting more memory than necessary for patterns with classes that
1487    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1488    
1489    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1490    compiling PCRE for use with Virtual Pascal.
1491    
1492    22. Small fix to the Makefile to make it work properly if the build is done
1493    outside the source tree.
1494    
1495    23. Added a new extension: a condition to go with recursion. If a conditional
1496    subpattern starts with (?(R) the "true" branch is used if recursion has
1497    happened, whereas the "false" branch is used only at the top level.
1498    
1499    24. When there was a very long string of literal characters (over 255 bytes
1500    without UTF support, over 250 bytes with UTF support), the computation of how
1501    much memory was required could be incorrect, leading to segfaults or other
1502    strange effects.
1503    
1504    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1505    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1506    there was a subsequent back reference to those brackets. This meant that, for
1507    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1508    possible to check for precisely this case. All we can do is abandon the
1509    optimization if .* occurs inside capturing brackets when there are any back
1510    references whatsoever. (See below for a better fix that came later.)
1511    
1512    26. The handling of the optimization for finding the first character of a
1513    non-anchored pattern, and for finding a character that is required later in the
1514    match were failing in some cases. This didn't break the matching; it just
1515    failed to optimize when it could. The way this is done has been re-implemented.
1516    
1517    27. Fixed typo in error message for invalid (?R item (it said "(?p").
1518    
1519    28. Added a new feature that provides some of the functionality that Perl
1520    provides with (?{...}). The facility is termed a "callout". The way it is done
1521    in PCRE is for the caller to provide an optional function, by setting
1522    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1523    global variable. By default it is unset, which disables all calling out. To get
1524    the function called, the regex must include (?C) at appropriate points. This
1525    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1526    This provides a means of identifying different callout points. When PCRE
1527    reaches such a point in the regex, if pcre_callout has been set, the external
1528    function is called. It is provided with data in a structure called
1529    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1530    matching continues; if it returns a non-zero value, the match at the current
1531    point fails. However, backtracking will occur if possible. [This was changed
1532    later and other features added - see item 49 below.]
1533    
1534    29. pcretest is upgraded to test the callout functionality. It provides a
1535    callout function that displays information. By default, it shows the start of
1536    the match and the current position in the text. There are some new data escapes
1537    to vary what happens:
1538    
1539        \C+         in addition, show current contents of captured substrings
1540        \C-         do not supply a callout function
1541        \C!n        return 1 when callout number n is reached
1542        \C!n!m      return 1 when callout number n is reached for the mth time
1543    
1544    30. If pcregrep was called with the -l option and just a single file name, it
1545    output "<stdin>" if a match was found, instead of the file name.
1546    
1547    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1548    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1549    pcre_exec(). This saves a malloc/free per call. The default value of
1550    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1551    when configuring.
1552    
1553    32. The default maximum size of a compiled pattern is 64K. There have been a
1554    few cases of people hitting this limit. The code now uses macros to handle the
1555    storing of links as offsets within the compiled pattern. It defaults to 2-byte
1556    links, but this can be changed to 3 or 4 bytes by --with-link-size when
1557    configuring. Tests 2 and 5 work only with 2-byte links because they output
1558    debugging information about compiled patterns.
1559    
1560    33. Internal code re-arrangements:
1561    
1562    (a) Moved the debugging function for printing out a compiled regex into
1563        its own source file (printint.c) and used #include to pull it into
1564        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1565        separate copies.
1566    
1567    (b) Defined the list of op-code names for debugging as a macro in
1568        internal.h so that it is next to the definition of the opcodes.
1569    
1570    (c) Defined a table of op-code lengths for simpler skipping along compiled
1571        code. This is again a macro in internal.h so that it is next to the
1572        definition of the opcodes.
1573    
1574    34. Added support for recursive calls to individual subpatterns, along the
1575    lines of Robin Houston's patch (but implemented somewhat differently).
1576    
1577    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1578    allow it to read and process whole directories in Win32. This code was
1579    contributed by Lionel Fourquaux; it has not been tested by me.
1580    
1581    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1582    used to name a group. Names consist of alphanumerics and underscores, and must
1583    be unique. Back references use the syntax (?P=name) and recursive calls use
1584    (?P>name) which is a PCRE extension to the Python extension. Groups still have
1585    numbers. The function pcre_fullinfo() can be used after compilation to extract
1586    a name/number map. There are three relevant calls:
1587    
1588      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
1589      PCRE_INFO_NAMECOUNT            yields the number of entries
1590      PCRE_INFO_NAMETABLE            yields a pointer to the map.
1591    
1592    The map is a vector of fixed-size entries. The size of each entry depends on
1593    the length of the longest name used. The first two bytes of each entry are the
1594    group number, most significant byte first. There follows the corresponding
1595    name, zero terminated. The names are in alphabetical order.
1596    
1597    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1598    case instead of 255. Making it the same both with and without UTF-8 support
1599    means that the same test output works with both.
1600    
1601    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1602    calling malloc() with a zero argument.
1603    
1604    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1605    optimization. I've improved things by keeping a bitmap of backreferences with
1606    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1607    fact referenced, the optimization can be applied. It is unlikely that a
1608    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1609    the match to follow \n) will appear inside brackets with a number greater than
1610    31, but if it does, any back reference > 31 suppresses the optimization.
1611    
1612    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1613    of disabling numbered capturing parentheses. Any opening parenthesis that is
1614    not followed by ? behaves as if it were followed by ?: but named parentheses
1615    can still be used for capturing (and they will acquire numbers in the usual
1616    way).
1617    
1618    41. Redesigned the return codes from the match() function into yes/no/error so
1619    that errors can be passed back from deep inside the nested calls. A malloc
1620    failure while inside a recursive subpattern call now causes the
1621    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1622    
1623    42. It is now possible to set a limit on the number of times the match()
1624    function is called in a call to pcre_exec(). This facility makes it possible to
1625    limit the amount of recursion and backtracking, though not in a directly
1626    obvious way, because the match() function is used in a number of different
1627    circumstances. The count starts from zero for each position in the subject
1628    string (for non-anchored patterns). The default limit is, for compatibility, a
1629    large number, namely 10 000 000. You can change this in two ways:
1630    
1631    (a) When configuring PCRE before making, you can use --with-match-limit=n
1632        to set a default value for the compiled library.
1633    
1634    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1635        a different value is set. See 45 below.
1636    
1637    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1638    
1639    43. Added a new function pcre_config(int, void *) to enable run-time extraction
1640    of things that can be changed at compile time. The first argument specifies
1641    what is wanted and the second points to where the information is to be placed.
1642    The current list of available information is:
1643    
1644      PCRE_CONFIG_UTF8
1645    
1646    The output is an integer that is set to one if UTF-8 support is available;
1647    otherwise it is set to zero.
1648    
1649      PCRE_CONFIG_NEWLINE
1650    
1651    The output is an integer that it set to the value of the code that is used for
1652    newline. It is either LF (10) or CR (13).
1653    
1654      PCRE_CONFIG_LINK_SIZE
1655    
1656    The output is an integer that contains the number of bytes used for internal
1657    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
1658    
1659      PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
1660    
1661    The output is an integer that contains the threshold above which the POSIX
1662    interface uses malloc() for output vectors. See item 31 above.
1663    
1664      PCRE_CONFIG_MATCH_LIMIT
1665    
1666    The output is an unsigned integer that contains the default limit of the number
1667    of match() calls in a pcre_exec() execution. See 42 above.
1668    
1669    44. pcretest has been upgraded by the addition of the -C option. This causes it
1670    to extract all the available output from the new pcre_config() function, and to
1671    output it. The program then exits immediately.
1672    
1673    45. A need has arisen to pass over additional data with calls to pcre_exec() in
1674    order to support additional features. One way would have been to define
1675    pcre_exec2() (for example) with extra arguments, but this would not have been
1676    extensible, and would also have required all calls to the original function to
1677    be mapped to the new one. Instead, I have chosen to extend the mechanism that
1678    is used for passing in "extra" data from pcre_study().
1679    
1680    The pcre_extra structure is now exposed and defined in pcre.h. It currently
1681    contains the following fields:
1682    
1683      flags         a bitmap indicating which of the following fields are set
1684      study_data    opaque data from pcre_study()
1685      match_limit   a way of specifying a limit on match() calls for a specific
1686                      call to pcre_exec()
1687      callout_data  data for callouts (see 49 below)
1688    
1689    The flag bits are also defined in pcre.h, and are
1690    
1691      PCRE_EXTRA_STUDY_DATA
1692      PCRE_EXTRA_MATCH_LIMIT
1693      PCRE_EXTRA_CALLOUT_DATA
1694    
1695    The pcre_study() function now returns one of these new pcre_extra blocks, with
1696    the actual study data pointed to by the study_data field, and the
1697    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
1698    before. That is, this change is entirely upwards-compatible and requires no
1699    change to existing code.
1700    
1701    If you want to pass in additional data to pcre_exec(), you can either place it
1702    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
1703    block.
1704    
1705    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
1706    data string contains the escape sequence \M, pcretest calls pcre_exec() several
1707    times with different match limits, until it finds the minimum value needed for
1708    pcre_exec() to complete. The value is then output. This can be instructive; for
1709    most simple matches the number is quite small, but for pathological cases it
1710    gets very large very quickly.
1711    
1712    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
1713    returns the size of the data block pointed to by the study_data field in a
1714    pcre_extra block, that is, the value that was passed as the argument to
1715    pcre_malloc() when PCRE was getting memory in which to place the information
1716    created by pcre_study(). The fourth argument should point to a size_t variable.
1717    pcretest has been extended so that this information is shown after a successful
1718    pcre_study() call when information about the compiled regex is being displayed.
1719    
1720    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
1721    because what follows is always an absolute path. (Later: it turns out that this
1722    is more than cosmetic for MinGW, because it doesn't like empty path
1723    components.)
1724    
1725    49. Some changes have been made to the callout feature (see 28 above):
1726    
1727    (i)  A callout function now has three choices for what it returns:
1728    
1729           0  =>  success, carry on matching
1730         > 0  =>  failure at this point, but backtrack if possible
1731         < 0  =>  serious error, return this value from pcre_exec()
1732    
1733         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
1734         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
1735         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
1736         use by callout functions. It will never be used by PCRE itself.
1737    
1738    (ii) The pcre_extra structure (see 45 above) has a void * field called
1739         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
1740         pcre_callout_block structure has a field of the same name. The contents of
1741         the field passed in the pcre_extra structure are passed to the callout
1742         function in the corresponding field in the callout block. This makes it
1743         easier to use the same callout-containing regex from multiple threads. For
1744         testing, the pcretest program has a new data escape
1745    
1746           \C*n        pass the number n (may be negative) as callout_data
1747    
1748         If the callout function in pcretest receives a non-zero value as
1749         callout_data, it returns that value.
1750    
1751    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
1752    there were some redundant $(CFLAGS) in commands that are now specified as
1753    $(LINK), which already includes $(CFLAGS).
1754    
1755    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
1756    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
1757    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
1758    one-byte characters throughout. Note that case-insensitive matching applies
1759    only to characters whose values are less than 256. PCRE doesn't support the
1760    notion of cases for higher-valued characters.
1761    
1762    (i)   A character class whose characters are all within 0-255 is handled as
1763          a bit map, and the map is inverted for negative classes. Previously, a
1764          character > 255 always failed to match such a class; however it should
1765          match if the class was a negative one (e.g. [^ab]). This has been fixed.
1766    
1767    (ii)  A negated character class with a single character < 255 is coded as
1768          "not this character" (OP_NOT). This wasn't working properly when the test
1769          character was multibyte, either singly or repeated.
1770    
1771    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
1772          mode, for example: \x{100}{2,3}.
1773    
1774    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
1775          singly or repeated) now correctly test multibyte characters. However,
1776          PCRE doesn't recognize any characters with values greater than 255 as
1777          digits, spaces, or word characters. Such characters always match \D, \S,
1778          and \W, and never match \d, \s, or \w.
1779    
1780    (v)   Classes may now contain characters and character ranges with values
1781          greater than 255. For example: [ab\x{100}-\x{400}].
1782    
1783    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
1784          PCRE in UTF-8 mode.
1785    
1786    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
1787    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
1788    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
1789    value.)
1790    
1791    53. The single man page has become too large. I have therefore split it up into
1792    a number of separate man pages. These also give rise to individual HTML pages;
1793    these are now put in a separate directory, and there is an index.html page that
1794    lists them all. Some hyperlinking between the pages has been installed.
1795    
1796    54. Added convenience functions for handling named capturing parentheses.
1797    
1798    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
1799    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
1800    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
1801    are faulted.
1802    
1803    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
1804    calling configure. These values are used when compiling the dftables.c program
1805    which is run to generate the source of the default character tables. They
1806    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
1807    you will need to set these values.
1808    
1809    57. Updated the building process for Windows DLL, as provided by Fred Cox.
1810    
1811    
1812    Version 3.9 02-Jan-02
1813    ---------------------
1814    
1815    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
1816    
1817    2. If --disable-static was given, the building process failed when trying to
1818    build pcretest and pcregrep. (For some reason it was using libtool to compile
1819    them, which is not right, as they aren't part of the library.)
1820    
1821    
1822    Version 3.8 18-Dec-01
1823    ---------------------
1824    
1825    1. The experimental UTF-8 code was completely screwed up. It was packing the
1826    bytes in the wrong order. How dumb can you get?
1827    
1828    
1829    Version 3.7 29-Oct-01
1830    ---------------------
1831    
1832    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
1833    This caused pcretest, when used on the test data, to segfault. Unfortunately,
1834    this didn't happen under Solaris 8, where I normally test things.
1835    
1836    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
1837    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
1838    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
1839    this fix an hour or so after the initial 3.7 release.)
1840    
1841    
1842    Version 3.6 23-Oct-01
1843    ---------------------
1844    
1845    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
1846    offsets passed as NULL with zero offset count.
1847    
1848    2. The config.guess and config.sub files had not been updated when I moved to
1849    the latest autoconf.
1850    
1851    
1852    Version 3.5 15-Aug-01
1853    ---------------------
1854    
1855    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
1856    had been forgotten.
1857    
1858    2. By using declared but undefined structures, we can avoid using "void"
1859    definitions in pcre.h while keeping the internal definitions of the structures
1860    private.
1861    
1862    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
1863    user point of view, this means that both static and shared libraries are built
1864    by default, but this can be individually controlled. More of the work of
1865    handling this static/shared cases is now inside libtool instead of PCRE's make
1866    file.
1867    
1868    4. The pcretest utility is now installed along with pcregrep because it is
1869    useful for users (to test regexs) and by doing this, it automatically gets
1870    relinked by libtool. The documentation has been turned into a man page, so
1871    there are now .1, .txt, and .html versions in /doc.
1872    
1873    5. Upgrades to pcregrep:
1874       (i)   Added long-form option names like gnu grep.
1875       (ii)  Added --help to list all options with an explanatory phrase.
1876       (iii) Added -r, --recursive to recurse into sub-directories.
1877       (iv)  Added -f, --file to read patterns from a file.
1878    
1879    6. pcre_exec() was referring to its "code" argument before testing that
1880    argument for NULL (and giving an error if it was NULL).
1881    
1882    7. Upgraded Makefile.in to allow for compiling in a different directory from
1883    the source directory.
1884    
1885    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
1886    options bits, the pointer it was passed was to an int instead of to an unsigned
1887    long int. This mattered only on 64-bit systems.
1888    
1889    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
1890    generated) instead of pcre.in, which it its source. Also made the same change
1891    in several of the .c files.
1892    
1893    10. A new release of gcc defines printf() as a macro, which broke pcretest
1894    because it had an ifdef in the middle of a string argument for printf(). Fixed
1895    by using separate calls to printf().
1896    
1897    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
1898    script, to force use of CR or LF instead of \n in the source. On non-Unix
1899    systems, the value can be set in config.h.
1900    
1901    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
1902    absolute limit. Changed the text of the error message to make this clear, and
1903    likewise updated the man page.
1904    
1905    13. The limit of 99 on the number of capturing subpatterns has been removed.
1906    The new limit is 65535, which I hope will not be a "real" limit.
1907    
1908    
1909    Version 3.4 22-Aug-00
1910    ---------------------
1911    
1912    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
1913    
1914    2. Diagnose condition (?(0) as an error instead of crashing on matching.
1915    
1916    
1917    Version 3.3 01-Aug-00
1918    ---------------------
1919    
1920    1. If an octal character was given, but the value was greater than \377, it
1921    was not getting masked to the least significant bits, as documented. This could
1922    lead to crashes in some systems.
1923    
1924    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
1925    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
1926    
1927    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
1928    These just pass their arguments on to (pcre_free)(), but they are provided
1929    because some uses of PCRE bind it to non-C systems that can call its functions,
1930    but cannot call free() or pcre_free() directly.
1931    
1932    4. Add "make test" as a synonym for "make check". Corrected some comments in
1933    the Makefile.
1934    
1935    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
1936    Makefile.
1937    
1938    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
1939    command called pgrep for grepping around the active processes.
1940    
1941    7. Added the beginnings of support for UTF-8 character strings.
1942    
1943    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
1944    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
1945    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
1946    out for the ar command.)
1947    
1948    
1949  Version 3.2 12-May-00  Version 3.2 12-May-00
1950  ---------------------  ---------------------

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