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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 7.5 31-Dec-07
5    ---------------------
6    
7    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
8        values in parens when parsing an RE using the C++ wrapper."
9    
10    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
11        Characters greater than 255 were excluded from the class instead of being
12        included.
13    
14    3.  The same bug as (2) above applied to negated POSIX classes such as
15        [:^space:].
16    
17    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
18        defined or documented. It seems to have been a typo for PCRE_STATIC, so
19        I have changed it.
20    
21    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
22        first named subpattern) and a construct such as (?&a) would reference the
23        first named subpattern whose name started with "a" (in other words, the
24        length check was missing). Both these problems are fixed. "Subpattern name
25        expected" is now given for (?&) (a zero-length name), and this patch also
26        makes it give the same error for \k'' (previously it complained that that
27        was a reference to a non-existent subpattern).
28    
29    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
30        this is right because (?- can be followed by option settings as well as by
31        digits. I have, however, made the messages clearer.
32    
33    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
34        than the number used in the conditional) now cause a compile-time error.
35        This is actually not compatible with Perl, which accepts such patterns, but
36        treats the conditional as always being FALSE (as PCRE used to), but it
37        seems to me that giving a diagnostic is better.
38    
39    8.  Change "alphameric" to the more common word "alphanumeric" in comments
40        and messages.
41    
42    9.  Fix two occurrences of "backslash" in comments that should have been
43        "backspace".
44    
45    10. Remove two redundant lines of code that can never be obeyed (their function
46        was moved elsewhere).
47    
48    11. The program that makes PCRE's Unicode character property table had a bug
49        which caused it to generate incorrect table entries for sequences of
50        characters that have the same character type, but are in different scripts.
51        It amalgamated them into a single range, with the script of the first of
52        them. In other words, some characters were in the wrong script. There were
53        thirteen such cases, affecting characters in the following ranges:
54    
55          U+002b0 - U+002c1
56          U+0060c - U+0060d
57          U+0061e - U+00612
58          U+0064b - U+0065e
59          U+0074d - U+0076d
60          U+01800 - U+01805
61          U+01d00 - U+01d77
62          U+01d9b - U+01dbf
63          U+0200b - U+0200f
64          U+030fc - U+030fe
65          U+03260 - U+0327f
66          U+0fb46 - U+0fbb1
67          U+10450 - U+1049d
68    
69    12. The -o option (show only the matching part of a line) for pcregrep was not
70        compatible with GNU grep in that, if there was more than one match in a
71        line, it showed only the first of them. It now behaves in the same way as
72        GNU grep.
73    
74    13. If the -o and -v options were combined for pcregrep, it printed a blank
75        line for every non-matching line. GNU grep prints nothing, and pcregrep now
76        does the same. The return code can be used to tell if there were any
77        non-matching lines.
78    
79    14. Added --file-offsets and --line-offsets to pcregrep.
80    
81    15. The pattern (?=something)(?R) was not being diagnosed as a potentially
82        infinitely looping recursion. The bug was that positive lookaheads were not
83        being skipped when checking for a possible empty match (negative lookaheads
84        and both kinds of lookbehind were skipped).
85    
86    16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
87        inclusion of <windows.h> to before rather than after the definition of
88        INVALID_FILE_ATTRIBUTES (patch from David Byron).
89    
90    17. Specifying a possessive quantifier with a specific limit for a Unicode
91        character property caused pcre_compile() to compile bad code, which led at
92        runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
93        are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
94        caused the error; without that there was no problem.
95    
96    18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
97    
98    19. Added --enable-pcretest-libreadline.
99    
100    20. In pcrecpp.cc, the variable 'count' was incremented twice in
101        RE::GlobalReplace(). As a result, the number of replacements returned was
102        double what it should be. I have removed one of the increments.
103    
104    21. Several CMake things:
105    
106        (1) Arranged that, when cmake is used on Unix, the libraries end up with
107            the names libpcre and libpcreposix, not just pcre and pcreposix.
108    
109        (2) The above change means that pcretest and pcregrep are now correctly
110            linked with the newly-built libraries, not previously installed ones.
111    
112        (3) Added PCRE_SUPPORT_LIBREADLINE, PCRE_SUPPORT_LIBZ, PCRE_SUPPORT_LIBBZ2.
113    
114    22. In UTF-8 mode, with newline set to "any", a pattern such as .*a.*=.b.*
115        crashed when matching a string such as a\x{2029}b (note that \x{2029} is a
116        UTF-8 newline character). The key issue is that the pattern starts .*;
117        this means that the match must be either at the beginning, or after a
118        newline. The bug was in the code for advancing after a failed match and
119        checking that the new position followed a newline. It was not taking
120        account of UTF-8 characters correctly.
121    
122    23. PCRE was behaving differently from Perl in the way it recognized POSIX
123        character classes. PCRE was not treating the sequence [:...:] as a
124        character class unless the ... were all letters. Perl, however, seems to
125        allow any characters between [: and :], though of course it rejects as
126        unknown any "names" that contain non-letters, because all the known class
127        names consist only of letters. Thus, Perl gives an error for [[:1234:]],
128        for example, whereas PCRE did not - it did not recognize a POSIX character
129        class. This seemed a bit dangerous, so the code has been changed to be
130        closer to Perl. The behaviour is not identical to Perl, because PCRE will
131        diagnose an unknown class for, for example, [[:l\ower:]] where Perl will
132        treat it as [[:lower:]]. However, PCRE does now give "unknown" errors where
133        Perl does, and where it didn't before.
134    
135    24. Rewrite so as to remove the single use of %n from pcregrep because in some
136        Windows environments %n is disabled by default.
137    
138    
139    Version 7.4 21-Sep-07
140    ---------------------
141    
142    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
143        means that a class such as [\s] counted as "explicit reference to CR or
144        LF". That isn't really right - the whole point of the change was to try to
145        help when there was an actual mention of one of the two characters. So now
146        the change happens only if \r or \n (or a literal CR or LF) character is
147        encountered.
148    
149    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
150        of both had grown to the point where there were only 3 bits left.
151        Fortunately, there was spare space in the data structure, and so I have
152        moved the internal flags into a new 16-bit field to free up more option
153        bits.
154    
155    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
156        but did not set the internal JCHANGED flag - either of these is enough to
157        control the way the "get" function works - but the PCRE_INFO_JCHANGED
158        facility is supposed to tell if (?J) was ever used, so now (?J) at the
159        start sets both bits.
160    
161    4.  Added options (at build time, compile time, exec time) to change \R from
162        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
163    
164    5.  doc/pcresyntax.html was missing from the distribution.
165    
166    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
167        compatibility, even though it is no longer used.
168    
169    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
170        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
171        windows.h file is present (where different names are used). [This was
172        reversed later after testing - see 16 below.]
173    
174    8.  Changed all #include <config.h> to #include "config.h". There were also
175        some further <pcre.h> cases that I changed to "pcre.h".
176    
177    9.  When pcregrep was used with the --colour option, it missed the line ending
178        sequence off the lines that it output.
179    
180    10. It was pointed out to me that arrays of string pointers cause lots of
181        relocations when a shared library is dynamically loaded. A technique of
182        using a single long string with a table of offsets can drastically reduce
183        these. I have refactored PCRE in four places to do this. The result is
184        dramatic:
185    
186          Originally:                          290
187          After changing UCP table:            187
188          After changing error message table:   43
189          After changing table of "verbs"       36
190          After changing table of Posix names   22
191    
192        Thanks to the folks working on Gregex for glib for this insight.
193    
194    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
195        unicode-properties was also set.
196    
197    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
198    
199    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
200        checked only for CRLF.
201    
202    14. Added casts to pcretest.c to avoid compiler warnings.
203    
204    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
205    
206    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
207        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
208        entirely. This removes changes made in 7 above.
209    
210    17. The CMake files have been updated, and there is now more information about
211        building with CMake in the NON-UNIX-USE document.
212    
213    
214    Version 7.3 28-Aug-07
215    ---------------------
216    
217     1. In the rejigging of the build system that eventually resulted in 7.1, the
218        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
219        brackets there is not right, since it causes compilers to look for an
220        installed pcre.h, not the version that is in the source that is being
221        compiled (which of course may be different). I have changed it back to:
222    
223          #include "pcre.h"
224    
225        I have a vague recollection that the change was concerned with compiling in
226        different directories, but in the new build system, that is taken care of
227        by the VPATH setting the Makefile.
228    
229     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
230        when the subject happened to end in the byte 0x85 (e.g. if the last
231        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
232        characters but of course it shouldn't be taken as a newline when it is part
233        of another character. The bug was that, for an unlimited repeat of . in
234        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
235        characters when looking for a newline.
236    
237     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
238    
239     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
240        in debug output.
241    
242     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
243        long printing in the pcrecpp unittest when running under MinGW.
244    
245     6. ESC_K was left out of the EBCDIC table.
246    
247     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
248        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
249        limit also applies to "virtual nesting" when a pattern is recursive, and in
250        this case 1000 isn't so big. I have been able to remove this limit at the
251        expense of backing off one optimization in certain circumstances. Normally,
252        when pcre_exec() would call its internal match() function recursively and
253        immediately return the result unconditionally, it uses a "tail recursion"
254        feature to save stack. However, when a subpattern that can match an empty
255        string has an unlimited repetition quantifier, it no longer makes this
256        optimization. That gives it a stack frame in which to save the data for
257        checking that an empty string has been matched. Previously this was taken
258        from the 1000-entry workspace that had been reserved. So now there is no
259        explicit limit, but more stack is used.
260    
261     8. Applied Daniel's patches to solve problems with the import/export magic
262        syntax that is required for Windows, and which was going wrong for the
263        pcreposix and pcrecpp parts of the library. These were overlooked when this
264        problem was solved for the main library.
265    
266     9. There were some crude static tests to avoid integer overflow when computing
267        the size of patterns that contain repeated groups with explicit upper
268        limits. As the maximum quantifier is 65535, the maximum group length was
269        set at 30,000 so that the product of these two numbers did not overflow a
270        32-bit integer. However, it turns out that people want to use groups that
271        are longer than 30,000 bytes (though not repeat them that many times).
272        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
273        made it possible to implement the integer overflow checks in a much more
274        dynamic way, which I have now done. The artificial limitation on group
275        length has been removed - we now have only the limit on the total length of
276        the compiled pattern, which depends on the LINK_SIZE setting.
277    
278    10. Fixed a bug in the documentation for get/copy named substring when
279        duplicate names are permitted. If none of the named substrings are set, the
280        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
281        empty string.
282    
283    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
284        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
285        because the ] is interpreted as the first data character and the
286        terminating ] is not found. PCRE has been made compatible with Perl in this
287        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
288        cause memory overwriting.
289    
290    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
291        string has been matched (to stop an infinite loop). It was not recognizing
292        a conditional subpattern that could match an empty string if that
293        subpattern was within another subpattern. For example, it looped when
294        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
295        condition was not nested. This bug has been fixed.
296    
297    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
298        past the start of the subject in the presence of bytes with the top bit
299        set, for example "\x8aBCD".
300    
301    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
302        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
303    
304    14. Optimized (?!) to (*FAIL).
305    
306    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
307        This restricts code points to be within the range 0 to 0x10FFFF, excluding
308        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
309        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
310        does: it's just the validity check that is more restrictive.
311    
312    16. Inserted checks for integer overflows during escape sequence (backslash)
313        processing, and also fixed erroneous offset values for syntax errors during
314        backslash processing.
315    
316    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
317        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
318    
319    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
320        caused an overrun.
321    
322    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
323        something other than just ASCII characters) inside a group that had an
324        unlimited repeat caused a loop at compile time (while checking to see
325        whether the group could match an empty string).
326    
327    20. Debugging a pattern containing \p or \P could cause a crash. For example,
328        [\P{Any}] did so. (Error in the code for printing property names.)
329    
330    21. An orphan \E inside a character class could cause a crash.
331    
332    22. A repeated capturing bracket such as (A)? could cause a wild memory
333        reference during compilation.
334    
335    23. There are several functions in pcre_compile() that scan along a compiled
336        expression for various reasons (e.g. to see if it's fixed length for look
337        behind). There were bugs in these functions when a repeated \p or \P was
338        present in the pattern. These operators have additional parameters compared
339        with \d, etc, and these were not being taken into account when moving along
340        the compiled data. Specifically:
341    
342        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
343            length.
344    
345        (b) An item such as \pL+ within a repeated group could cause crashes or
346            loops.
347    
348        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
349            "reference to non-existent subpattern" error.
350    
351        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
352    
353    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
354        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
355    
356    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
357    
358    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
359        character were causing crashes (broken optimization).
360    
361    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
362        \p or \P) caused a compile-time loop.
363    
364    28. More problems have arisen in unanchored patterns when CRLF is a valid line
365        break. For example, the unstudied pattern [\r\n]A does not match the string
366        "\r\nA" because change 7.0/46 below moves the current point on by two
367        characters after failing to match at the start. However, the pattern \nA
368        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
369        the same is true. There doesn't seem any very clean way out of this, but
370        what I have chosen to do makes the common cases work: PCRE now takes note
371        of whether there can be an explicit match for \r or \n anywhere in the
372        pattern, and if so, 7.0/46 no longer applies. As part of this change,
373        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
374        pattern has explicit CR or LF references.
375    
376    29. Added (*CR) etc for changing newline setting at start of pattern.
377    
378    
379    Version 7.2 19-Jun-07
380    ---------------------
381    
382     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
383        which is apparently normally available under Windows.
384    
385     2. Re-jig the pcregrep tests with different newline settings in an attempt
386        to make them independent of the local environment's newline setting.
387    
388     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
389    
390     4. Some of the "internals" tests were previously cut out when the link size
391        was not 2, because the output contained actual offsets. The recent new
392        "Z" feature of pcretest means that these can be cut out, making the tests
393        usable with all link sizes.
394    
395     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
396        stack recursion. This gives a massive performance boost under BSD, but just
397        a small improvement under Linux. However, it saves one field in the frame
398        in all cases.
399    
400     6. Added more features from the forthcoming Perl 5.10:
401    
402        (a) (?-n) (where n is a string of digits) is a relative subroutine or
403            recursion call. It refers to the nth most recently opened parentheses.
404    
405        (b) (?+n) is also a relative subroutine call; it refers to the nth next
406            to be opened parentheses.
407    
408        (c) Conditions that refer to capturing parentheses can be specified
409            relatively, for example, (?(-2)... or (?(+3)...
410    
411        (d) \K resets the start of the current match so that everything before
412            is not part of it.
413    
414        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
415    
416        (f) \g{name} is another synonym - part of Perl 5.10's unification of
417            reference syntax.
418    
419        (g) (?| introduces a group in which the numbering of parentheses in each
420            alternative starts with the same number.
421    
422        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
423    
424     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
425        PCRE_INFO_JCHANGED.
426    
427     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
428        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
429        for detecting groups that can match an empty string.
430    
431     9. A pattern with a very large number of alternatives (more than several
432        hundred) was running out of internal workspace during the pre-compile
433        phase, where pcre_compile() figures out how much memory will be needed. A
434        bit of new cunning has reduced the workspace needed for groups with
435        alternatives. The 1000-alternative test pattern now uses 12 bytes of
436        workspace instead of running out of the 4096 that are available.
437    
438    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
439    
440    11. Applied patch from Google to remove an optimization that didn't quite work.
441        The report of the bug said:
442    
443          pcrecpp::RE("a*").FullMatch("aaa") matches, while
444          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
445          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
446    
447    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
448        it matched the wrong number of bytes.
449    
450    
451    Version 7.1 24-Apr-07
452    ---------------------
453    
454     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
455        that is more "standard", making use of automake and other Autotools. There
456        is some re-arrangement of the files and adjustment of comments consequent
457        on this.
458    
459     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
460        for recursive directory scanning broke on some systems because the files
461        are not scanned in any specific order and on different systems the order
462        was different. A call to "sort" has been inserted into RunGrepTest for the
463        approprate test as a short-term fix. In the longer term there may be an
464        alternative.
465    
466     3. I had an email from Eric Raymond about problems translating some of PCRE's
467        man pages to HTML (despite the fact that I distribute HTML pages, some
468        people do their own conversions for various reasons). The problems
469        concerned the use of low-level troff macros .br and .in. I have therefore
470        removed all such uses from the man pages (some were redundant, some could
471        be replaced by .nf/.fi pairs). The 132html script that I use to generate
472        HTML has been updated to handle .nf/.fi and to complain if it encounters
473        .br or .in.
474    
475     4. Updated comments in configure.ac that get placed in config.h.in and also
476        arranged for config.h to be included in the distribution, with the name
477        config.h.generic, for the benefit of those who have to compile without
478        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
479    
480     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
481        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
482        makevp.bat for the current PCRE, using the additional files
483        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
484    
485     6. A Windows user reported a minor discrepancy with test 2, which turned out
486        to be caused by a trailing space on an input line that had got lost in his
487        copy. The trailing space was an accident, so I've just removed it.
488    
489     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
490        that is needed.
491    
492     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
493        as "const" (a) because they are and (b) because it helps the PHP
494        maintainers who have recently made a script to detect big data structures
495        in the php code that should be moved to the .rodata section. I remembered
496        to update Builducptable as well, so it won't revert if ucptable.h is ever
497        re-created.
498    
499     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
500        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
501        order to be able to cut out the UTF-8 tables in the latter when UTF-8
502        support is not required. This saves 1.5-2K of code, which is important in
503        some applications.
504    
505        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
506        so as not to refer to the tables, even though these functions will never be
507        called when UTF-8 support is disabled. Otherwise there are problems with a
508        shared library.
509    
510    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
511    
512        (a) It was defining its arguments as char * instead of void *.
513    
514        (b) It was assuming that all moves were upwards in memory; this was true
515            a long time ago when I wrote it, but is no longer the case.
516    
517        The emulated memove() is provided for those environments that have neither
518        memmove() nor bcopy(). I didn't think anyone used it these days, but that
519        is clearly not the case, as these two bugs were recently reported.
520    
521    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
522        and Detrail to create the HTML documentation, the .txt form of the man
523        pages, and it removes trailing spaces from listed files. It also creates
524        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
525        case, it wraps all the #defines with #ifndefs. This script should be run
526        before "make dist".
527    
528    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
529        with Unicode property support.
530    
531        (a) For a maximizing quantifier, if the two different cases of the
532            character were of different lengths in their UTF-8 codings (there are
533            some cases like this - I found 11), and the matching function had to
534            back up over a mixture of the two cases, it incorrectly assumed they
535            were both the same length.
536    
537        (b) When PCRE was configured to use the heap rather than the stack for
538            recursion during matching, it was not correctly preserving the data for
539            the other case of a UTF-8 character when checking ahead for a match
540            while processing a minimizing repeat. If the check also involved
541            matching a wide character, but failed, corruption could cause an
542            erroneous result when trying to check for a repeat of the original
543            character.
544    
545    13. Some tidying changes to the testing mechanism:
546    
547        (a) The RunTest script now detects the internal link size and whether there
548            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
549            values substituted by "configure". (The RunGrepTest script already did
550            this for UTF-8.) The configure.ac script no longer substitutes the
551            relevant variables.
552    
553        (b) The debugging options /B and /D in pcretest show the compiled bytecode
554            with length and offset values. This means that the output is different
555            for different internal link sizes. Test 2 is skipped for link sizes
556            other than 2 because of this, bypassing the problem. Unfortunately,
557            there was also a test in test 3 (the locale tests) that used /B and
558            failed for link sizes other than 2. Rather than cut the whole test out,
559            I have added a new /Z option to pcretest that replaces the length and
560            offset values with spaces. This is now used to make test 3 independent
561            of link size. (Test 2 will be tidied up later.)
562    
563    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
564        segmentation fault instead of returning the appropriate error message.
565    
566    15. In multiline mode when the newline sequence was set to "any", the pattern
567        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
568        This doesn't seem right; it now treats the CRLF combination as the line
569        ending, and so does not match in that case. It's only a pattern such as ^$
570        that would hit this one: something like ^ABC$ would have failed after \r
571        and then tried again after \r\n.
572    
573    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
574        in an attempt to make files that differ only in their line terminators
575        compare equal. This works on Linux.
576    
577    17. Under certain error circumstances pcregrep might try to free random memory
578        as it exited. This is now fixed, thanks to valgrind.
579    
580    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
581        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
582        was because its rules for how to advance for /g after matching an empty
583        string at the end of a line did not allow for this case. They now check for
584        it specially.
585    
586    20. pcretest is supposed to handle patterns and data of any length, by
587        extending its buffers when necessary. It was getting this wrong when the
588        buffer for a data line had to be extended.
589    
590    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
591        CRLF as a newline sequence.
592    
593    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
594        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
595        I have nevertheless tidied it up.
596    
597    23. Added some casts to kill warnings from HP-UX ia64 compiler.
598    
599    24. Added a man page for pcre-config.
600    
601    
602    Version 7.0 19-Dec-06
603    ---------------------
604    
605     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
606        moving to gcc 4.1.1.
607    
608     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
609        sys/time.h, which is documented as needed for this function. It doesn't
610        seem to matter on Linux, but it showed up on some releases of OS X.
611    
612     3. It seems that there are systems where bytes whose values are greater than
613        127 match isprint() in the "C" locale. The "C" locale should be the
614        default when a C program starts up. In most systems, only ASCII printing
615        characters match isprint(). This difference caused the output from pcretest
616        to vary, making some of the tests fail. I have changed pcretest so that:
617    
618        (a) When it is outputting text in the compiled version of a pattern, bytes
619            other than 32-126 are always shown as hex escapes.
620    
621        (b) When it is outputting text that is a matched part of a subject string,
622            it does the same, unless a different locale has been set for the match
623            (using the /L modifier). In this case, it uses isprint() to decide.
624    
625     4. Fixed a major bug that caused incorrect computation of the amount of memory
626        required for a compiled pattern when options that changed within the
627        pattern affected the logic of the preliminary scan that determines the
628        length. The relevant options are -x, and -i in UTF-8 mode. The result was
629        that the computed length was too small. The symptoms of this bug were
630        either the PCRE error "internal error: code overflow" from pcre_compile(),
631        or a glibc crash with a message such as "pcretest: free(): invalid next
632        size (fast)". Examples of patterns that provoked this bug (shown in
633        pcretest format) are:
634    
635          /(?-x: )/x
636          /(?x)(?-x: \s*#\s*)/
637          /((?i)[\x{c0}])/8
638          /(?i:[\x{c0}])/8
639    
640        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
641        is now done differently.
642    
643     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
644        wrapper classes; (b) implement a new function in the C++ scanner that is
645        more efficient than the old way of doing things because it avoids levels of
646        recursion in the regex matching; (c) add a paragraph to the documentation
647        for the FullMatch() function.
648    
649     6. The escape sequence \n was being treated as whatever was defined as
650        "newline". Not only was this contrary to the documentation, which states
651        that \n is character 10 (hex 0A), but it also went horribly wrong when
652        "newline" was defined as CRLF. This has been fixed.
653    
654     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
655        was being set to -1 for the "end of line" case (supposedly a value that no
656        character can have). Though this value is never used (the check for end of
657        line is "zero bytes in current character"), it caused compiler complaints.
658        I've changed it to 0xffffffff.
659    
660     8. In pcre_version.c, the version string was being built by a sequence of
661        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
662        string (as it is for production releases) called a macro with an empty
663        argument. The C standard says the result of this is undefined. The gcc
664        compiler treats it as an empty string (which was what was wanted) but it is
665        reported that Visual C gives an error. The source has been hacked around to
666        avoid this problem.
667    
668     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
669        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
670        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
671        of them did).
672    
673    10. Originally, pcretest opened its input and output without "b"; then I was
674        told that "b" was needed in some environments, so it was added for release
675        5.0 to both the input and output. (It makes no difference on Unix-like
676        systems.) Later I was told that it is wrong for the input on Windows. I've
677        now abstracted the modes into two macros, to make it easier to fiddle with
678        them, and removed "b" from the input mode under Windows.
679    
680    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
681    
682    12. Added -help and --help to pcretest as an official way of being reminded
683        of the options.
684    
685    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
686        and pcrecpp.cc because they annoy compilers at high warning levels.
687    
688    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
689    
690    15. Fixed an occurrence of == in configure.ac that should have been = (shell
691        scripts are not C programs :-) and which was not noticed because it works
692        on Linux.
693    
694    16. pcretest is supposed to handle any length of pattern and data line (as one
695        line or as a continued sequence of lines) by extending its input buffer if
696        necessary. This feature was broken for very long pattern lines, leading to
697        a string of junk being passed to pcre_compile() if the pattern was longer
698        than about 50K.
699    
700    17. I have done a major re-factoring of the way pcre_compile() computes the
701        amount of memory needed for a compiled pattern. Previously, there was code
702        that made a preliminary scan of the pattern in order to do this. That was
703        OK when PCRE was new, but as the facilities have expanded, it has become
704        harder and harder to keep it in step with the real compile phase, and there
705        have been a number of bugs (see for example, 4 above). I have now found a
706        cunning way of running the real compile function in a "fake" mode that
707        enables it to compute how much memory it would need, while actually only
708        ever using a few hundred bytes of working memory and without too many
709        tests of the mode. This should make future maintenance and development
710        easier. A side effect of this work is that the limit of 200 on the nesting
711        depth of parentheses has been removed (though this was never a serious
712        limitation, I suspect). However, there is a downside: pcre_compile() now
713        runs more slowly than before (30% or more, depending on the pattern). I
714        hope this isn't a big issue. There is no effect on runtime performance.
715    
716    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
717        newline (only possible for the last line of a file) and it was a
718        pattern that set a locale (followed by /Lsomething), pcretest crashed.
719    
720    19. Added additional timing features to pcretest. (1) The -tm option now times
721        matching only, not compiling. (2) Both -t and -tm can be followed, as a
722        separate command line item, by a number that specifies the number of
723        repeats to use when timing. The default is 50000; this gives better
724        precision, but takes uncomfortably long for very large patterns.
725    
726    20. Extended pcre_study() to be more clever in cases where a branch of a
727        subpattern has no definite first character. For example, (a*|b*)[cd] would
728        previously give no result from pcre_study(). Now it recognizes that the
729        first character must be a, b, c, or d.
730    
731    21. There was an incorrect error "recursive call could loop indefinitely" if
732        a subpattern (or the entire pattern) that was being tested for matching an
733        empty string contained only one non-empty item after a nested subpattern.
734        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
735        incorrectly, because the \d was being skipped in the check.
736    
737    22. The pcretest program now has a new pattern option /B and a command line
738        option -b, which is equivalent to adding /B to every pattern. This causes
739        it to show the compiled bytecode, without the additional information that
740        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
741        is the same as /B/I).
742    
743    23. A new optimization is now able automatically to treat some sequences such
744        as a*b as a*+b. More specifically, if something simple (such as a character
745        or a simple class like \d) has an unlimited quantifier, and is followed by
746        something that cannot possibly match the quantified thing, the quantifier
747        is automatically "possessified".
748    
749    24. A recursive reference to a subpattern whose number was greater than 39
750        went wrong under certain circumstances in UTF-8 mode. This bug could also
751        have affected the operation of pcre_study().
752    
753    25. Realized that a little bit of performance could be had by replacing
754        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
755    
756    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
757    
758    27. Possessive quantifiers such as a++ were previously implemented by turning
759        them into atomic groups such as ($>a+). Now they have their own opcodes,
760        which improves performance. This includes the automatically created ones
761        from 23 above.
762    
763    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
764        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
765        the first matched character to be a colon. This applied both to named and
766        numbered groups.
767    
768    29. The ucpinternal.h header file was missing its idempotency #ifdef.
769    
770    30. I was sent a "project" file called libpcre.a.dev which I understand makes
771        building PCRE on Windows easier, so I have included it in the distribution.
772    
773    31. There is now a check in pcretest against a ridiculously large number being
774        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
775        loop, the loop is abandoned.
776    
777    32. Forward references to subpatterns in conditions such as (?(2)...) where
778        subpattern 2 is defined later cause pcre_compile() to search forwards in
779        the pattern for the relevant set of parentheses. This search went wrong
780        when there were unescaped parentheses in a character class, parentheses
781        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
782    
783    33. "Subroutine" calls and backreferences were previously restricted to
784        referencing subpatterns earlier in the regex. This restriction has now
785        been removed.
786    
787    34. Added a number of extra features that are going to be in Perl 5.10. On the
788        whole, these are just syntactic alternatives for features that PCRE had
789        previously implemented using the Python syntax or my own invention. The
790        other formats are all retained for compatibility.
791    
792        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
793            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
794            also .NET compatible.
795    
796        (b) A recursion or subroutine call to a named group can now be defined as
797            (?&name) as well as (?P>name).
798    
799        (c) A backreference to a named group can now be defined as \k<name> or
800            \k'name' as well as (?P=name). The new forms, as well as being in Perl
801            5.10, are also .NET compatible.
802    
803        (d) A conditional reference to a named group can now use the syntax
804            (?(<name>) or (?('name') as well as (?(name).
805    
806        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
807            groups (named and numbered) that are never evaluated inline, but can be
808            called as "subroutines" from elsewhere. In effect, the DEFINE condition
809            is always false. There may be only one alternative in such a group.
810    
811        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
812            as the simple (?(R). The condition is true only if the most recent
813            recursion is that of the given number or name. It does not search out
814            through the entire recursion stack.
815    
816        (g) The escape \gN or \g{N} has been added, where N is a positive or
817            negative number, specifying an absolute or relative reference.
818    
819    35. Tidied to get rid of some further signed/unsigned compiler warnings and
820        some "unreachable code" warnings.
821    
822    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
823        things, this adds five new scripts.
824    
825    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
826        There were also incompatibilities regarding the handling of \Q..\E inside
827        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
828        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
829    
830    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
831        matches an empty string, and forcibly breaks the loop. There were bugs in
832        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
833        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
834        separate and independent bugs (that affected different cases) have been
835        fixed.
836    
837    39. Refactored the code to abolish the use of different opcodes for small
838        capturing bracket numbers. This is a tidy that I avoided doing when I
839        removed the limit on the number of capturing brackets for 3.5 back in 2001.
840        The new approach is not only tidier, it makes it possible to reduce the
841        memory needed to fix the previous bug (38).
842    
843    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
844        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
845        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
846        mode.
847    
848    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
849        report.
850    
851    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
852        copy construction and assignment in the C++ wrapper.
853    
854    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
855        couple of bugs that could have given wrong results in the "--newline=crlf"
856        case.
857    
858    44. Added a number of casts and did some reorganization of signed/unsigned int
859        variables following suggestions from Dair Grant. Also renamed the variable
860        "this" as "item" because it is a C++ keyword.
861    
862    45. Arranged for dftables to add
863    
864          #include "pcre_internal.h"
865    
866        to pcre_chartables.c because without it, gcc 4.x may remove the array
867        definition from the final binary if PCRE is built into a static library and
868        dead code stripping is activated.
869    
870    46. For an unanchored pattern, if a match attempt fails at the start of a
871        newline sequence, and the newline setting is CRLF or ANY, and the next two
872        characters are CRLF, advance by two characters instead of one.
873    
874    
875    Version 6.7 04-Jul-06
876    ---------------------
877    
878     1. In order to handle tests when input lines are enormously long, pcretest has
879        been re-factored so that it automatically extends its buffers when
880        necessary. The code is crude, but this _is_ just a test program. The
881        default size has been increased from 32K to 50K.
882    
883     2. The code in pcre_study() was using the value of the re argument before
884        testing it for NULL. (Of course, in any sensible call of the function, it
885        won't be NULL.)
886    
887     3. The memmove() emulation function in pcre_internal.h, which is used on
888        systems that lack both memmove() and bcopy() - that is, hardly ever -
889        was missing a "static" storage class specifier.
890    
891     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
892        containing an extended class (one that cannot be represented by a bitmap
893        because it contains high-valued characters or Unicode property items, e.g.
894        [\pZ]). Almost always one would set UTF-8 mode when processing such a
895        pattern, but PCRE should not loop if you do not (it no longer does).
896        [Detail: two cases were found: (a) a repeated subpattern containing an
897        extended class; (b) a recursive reference to a subpattern that followed a
898        previous extended class. It wasn't skipping over the extended class
899        correctly when UTF-8 mode was not set.]
900    
901     5. A negated single-character class was not being recognized as fixed-length
902        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
903        compile error "lookbehind assertion is not fixed length".
904    
905     6. The RunPerlTest auxiliary script was showing an unexpected difference
906        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
907        write a Perl script that can interpret lines of an input file either as
908        byte characters or as UTF-8, which is what "perltest" was being required to
909        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
910        can't do is switch easily at run time between having the "use utf8;" pragma
911        or not. In the end, I fudged it by using the RunPerlTest script to insert
912        "use utf8;" explicitly for the UTF-8 tests.
913    
914     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
915        the end of the subject string, contrary to the documentation and to what
916        Perl does. This was true of both matching functions. Now it matches only at
917        the start of the subject and immediately after *internal* newlines.
918    
919     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
920        a pointer to an int instead of a pointer to an unsigned long int. This
921        caused problems on 64-bit systems.
922    
923     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
924        instance of the 'standard' template library not being so standard".
925    
926    10. There was no check on the number of named subpatterns nor the maximum
927        length of a subpattern name. The product of these values is used to compute
928        the size of the memory block for a compiled pattern. By supplying a very
929        long subpattern name and a large number of named subpatterns, the size
930        computation could be caused to overflow. This is now prevented by limiting
931        the length of names to 32 characters, and the number of named subpatterns
932        to 10,000.
933    
934    11. Subpatterns that are repeated with specific counts have to be replicated in
935        the compiled pattern. The size of memory for this was computed from the
936        length of the subpattern and the repeat count. The latter is limited to
937        65535, but there was no limit on the former, meaning that integer overflow
938        could in principle occur. The compiled length of a repeated subpattern is
939        now limited to 30,000 bytes in order to prevent this.
940    
941    12. Added the optional facility to have named substrings with the same name.
942    
943    13. Added the ability to use a named substring as a condition, using the
944        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
945        are numbers (not recommended). Forward references are permitted.
946    
947    14. Added forward references in named backreferences (if you see what I mean).
948    
949    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
950        pattern could run off the end of the subject. For example, the pattern
951        "(?s)(.{1,5})"8 did this with the subject "ab".
952    
953    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
954        PCRE_CASELESS was set when matching characters that were quantified with ?
955        or *.
956    
957    17. A character class other than a single negated character that had a minimum
958        but no maximum quantifier - for example [ab]{6,} - was not handled
959        correctly by pce_dfa_exec(). It would match only one character.
960    
961    18. A valid (though odd) pattern that looked like a POSIX character
962        class but used an invalid character after [ (for example [[,abc,]]) caused
963        pcre_compile() to give the error "Failed: internal error: code overflow" or
964        in some cases to crash with a glibc free() error. This could even happen if
965        the pattern terminated after [[ but there just happened to be a sequence of
966        letters, a binary zero, and a closing ] in the memory that followed.
967    
968    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
969        over the years. Originally (before any Unicode support), just the bottom 8
970        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
971        output from "man perlunicode" includes this:
972    
973          The regular expression compiler produces polymorphic opcodes.  That
974          is, the pattern adapts to the data and automatically switches to
975          the Unicode character scheme when presented with Unicode data--or
976          instead uses a traditional byte scheme when presented with byte
977          data.
978    
979        Sadly, a wide octal escape does not cause a switch, and in a string with
980        no other multibyte characters, these octal escapes are treated as before.
981        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
982        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
983        Unicode string.
984    
985        I have not perpetrated such confusion in PCRE. Up till now, it took just
986        the bottom 8 bits, as in old Perl. I have now made octal escapes with
987        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
988        translate to the appropriate multibyte character.
989    
990    29. Applied some refactoring to reduce the number of warnings from Microsoft
991        and Borland compilers. This has included removing the fudge introduced
992        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
993        a warning about an unused variable.
994    
995    21. PCRE has not included VT (character 0x0b) in the set of whitespace
996        characters since release 4.0, because Perl (from release 5.004) does not.
997        [Or at least, is documented not to: some releases seem to be in conflict
998        with the documentation.] However, when a pattern was studied with
999        pcre_study() and all its branches started with \s, PCRE still included VT
1000        as a possible starting character. Of course, this did no harm; it just
1001        caused an unnecessary match attempt.
1002    
1003    22. Removed a now-redundant internal flag bit that recorded the fact that case
1004        dependency changed within the pattern. This was once needed for "required
1005        byte" processing, but is no longer used. This recovers a now-scarce options
1006        bit. Also moved the least significant internal flag bit to the most-
1007        significant bit of the word, which was not previously used (hangover from
1008        the days when it was an int rather than a uint) to free up another bit for
1009        the future.
1010    
1011    23. Added support for CRLF line endings as well as CR and LF. As well as the
1012        default being selectable at build time, it can now be changed at runtime
1013        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
1014        specify that it is scanning data with non-default line endings.
1015    
1016    24. Changed the definition of CXXLINK to make it agree with the definition of
1017        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
1018    
1019    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
1020        recursions. This makes a big different to stack usage for some patterns.
1021    
1022    26. If a subpattern containing a named recursion or subroutine reference such
1023        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
1024        the space required for the compiled pattern went wrong and gave too small a
1025        value. Depending on the environment, this could lead to "Failed: internal
1026        error: code overflow at offset 49" or "glibc detected double free or
1027        corruption" errors.
1028    
1029    27. Applied patches from Google (a) to support the new newline modes and (b) to
1030        advance over multibyte UTF-8 characters in GlobalReplace.
1031    
1032    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
1033        difference for some implementation of PCRE in some Windows version.
1034    
1035    29. Added some extra testing facilities to pcretest:
1036    
1037        \q<number>   in a data line sets the "match limit" value
1038        \Q<number>   in a data line sets the "match recursion limt" value
1039        -S <number>  sets the stack size, where <number> is in megabytes
1040    
1041        The -S option isn't available for Windows.
1042    
1043    
1044    Version 6.6 06-Feb-06
1045    ---------------------
1046    
1047     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
1048        in pcreposix.h. I have copied the definition from pcre.h.
1049    
1050     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
1051        because pcre.h is no longer a built file.
1052    
1053     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
1054        not normally included in the compiled code.
1055    
1056    
1057    Version 6.5 01-Feb-06
1058    ---------------------
1059    
1060     1. When using the partial match feature with pcre_dfa_exec(), it was not
1061        anchoring the second and subsequent partial matches at the new starting
1062        point. This could lead to incorrect results. For example, with the pattern
1063        /1234/, partially matching against "123" and then "a4" gave a match.
1064    
1065     2. Changes to pcregrep:
1066    
1067        (a) All non-match returns from pcre_exec() were being treated as failures
1068            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
1069            error message is output. Some extra information is given for the
1070            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
1071            probably the only errors that are likely to be caused by users (by
1072            specifying a regex that has nested indefinite repeats, for instance).
1073            If there are more than 20 of these errors, pcregrep is abandoned.
1074    
1075        (b) A binary zero was treated as data while matching, but terminated the
1076            output line if it was written out. This has been fixed: binary zeroes
1077            are now no different to any other data bytes.
1078    
1079        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
1080            used to set a locale for matching. The --locale=xxxx long option has
1081            been added (no short equivalent) to specify a locale explicitly on the
1082            pcregrep command, overriding the environment variables.
1083    
1084        (d) When -B was used with -n, some line numbers in the output were one less
1085            than they should have been.
1086    
1087        (e) Added the -o (--only-matching) option.
1088    
1089        (f) If -A or -C was used with -c (count only), some lines of context were
1090            accidentally printed for the final match.
1091    
1092        (g) Added the -H (--with-filename) option.
1093    
1094        (h) The combination of options -rh failed to suppress file names for files
1095            that were found from directory arguments.
1096    
1097        (i) Added the -D (--devices) and -d (--directories) options.
1098    
1099        (j) Added the -F (--fixed-strings) option.
1100    
1101        (k) Allow "-" to be used as a file name for -f as well as for a data file.
1102    
1103        (l) Added the --colo(u)r option.
1104    
1105        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
1106            is not present by default.
1107    
1108     3. A nasty bug was discovered in the handling of recursive patterns, that is,
1109        items such as (?R) or (?1), when the recursion could match a number of
1110        alternatives. If it matched one of the alternatives, but subsequently,
1111        outside the recursion, there was a failure, the code tried to back up into
1112        the recursion. However, because of the way PCRE is implemented, this is not
1113        possible, and the result was an incorrect result from the match.
1114    
1115        In order to prevent this happening, the specification of recursion has
1116        been changed so that all such subpatterns are automatically treated as
1117        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
1118    
1119     4. I had overlooked the fact that, in some locales, there are characters for
1120        which isalpha() is true but neither isupper() nor islower() are true. In
1121        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
1122        and ordfeminine) are like this. This affected the treatment of \w and \W
1123        when they appeared in character classes, but not when they appeared outside
1124        a character class. The bit map for "word" characters is now created
1125        separately from the results of isalnum() instead of just taking it from the
1126        upper, lower, and digit maps. (Plus the underscore character, of course.)
1127    
1128     5. The above bug also affected the handling of POSIX character classes such as
1129        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
1130        permanent tables. Instead, the bit maps for such a class were previously
1131        created as the appropriate unions of the upper, lower, and digit bitmaps.
1132        Now they are created by subtraction from the [[:word:]] class, which has
1133        its own bitmap.
1134    
1135     6. The [[:blank:]] character class matches horizontal, but not vertical space.
1136        It is created by subtracting the vertical space characters (\x09, \x0a,
1137        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
1138        subtraction was done in the overall bitmap for a character class, meaning
1139        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
1140        be recognized. This bug has been fixed.
1141    
1142     7. Patches from the folks at Google:
1143    
1144          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
1145          real life, but is still worth protecting against".
1146    
1147          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
1148          regular expressions".
1149    
1150          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1151          have it.
1152    
1153          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1154          "configure" and the latter not, in order to fix a problem somebody had
1155          with compiling the Arg class on HP-UX.
1156    
1157          (e) Improve the error-handling of the C++ wrapper a little bit.
1158    
1159          (f) New tests for checking recursion limiting.
1160    
1161     8. The pcre_memmove() function, which is used only if the environment does not
1162        have a standard memmove() function (and is therefore rarely compiled),
1163        contained two bugs: (a) use of int instead of size_t, and (b) it was not
1164        returning a result (though PCRE never actually uses the result).
1165    
1166     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1167        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1168        returned instead of calling malloc() with an overflowing number that would
1169        most likely cause subsequent chaos.
1170    
1171    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1172    
1173    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
1174        with this option is matched, the nmatch and pmatch options of regexec() are
1175        ignored.
1176    
1177    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
1178        provided in case anyone wants to the the POSIX interface with UTF-8
1179        strings.
1180    
1181    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
1182        C++ linking (needed for some HP-UX environments).
1183    
1184    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
1185        (unused parameter) and in the pcre_printint() function (omitted "default"
1186        switch label when the default is to do nothing).
1187    
1188    15. Added some code to make it possible, when PCRE is compiled as a C++
1189        library, to replace subject pointers for pcre_exec() with a smart pointer
1190        class, thus making it possible to process discontinuous strings.
1191    
1192    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
1193        much the same function. They were added by different people who were trying
1194        to make PCRE easy to compile on non-Unix systems. It has been suggested
1195        that PCRE_EXPORT be abolished now that there is more automatic apparatus
1196        for compiling on Windows systems. I have therefore replaced it with
1197        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
1198        defaults to "extern" for C or "extern C" for C++, which works fine on
1199        Unix-like systems. It is now possible to override the value of PCRE_DATA_
1200        SCOPE with something explicit in config.h. In addition:
1201    
1202        (a) pcreposix.h still had just "extern" instead of either of these macros;
1203            I have replaced it with PCRE_DATA_SCOPE.
1204    
1205        (b) Functions such as _pcre_xclass(), which are internal to the library,
1206            but external in the C sense, all had PCRE_EXPORT in their definitions.
1207            This is apparently wrong for the Windows case, so I have removed it.
1208            (It makes no difference on Unix-like systems.)
1209    
1210    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
1211        of recursive calls to match(). This is different to MATCH_LIMIT because
1212        that limits the total number of calls to match(), not all of which increase
1213        the depth of recursion. Limiting the recursion depth limits the amount of
1214        stack (or heap if NO_RECURSE is set) that is used. The default can be set
1215        when PCRE is compiled, and changed at run time. A patch from Google adds
1216        this functionality to the C++ interface.
1217    
1218    18. Changes to the handling of Unicode character properties:
1219    
1220        (a) Updated the table to Unicode 4.1.0.
1221    
1222        (b) Recognize characters that are not in the table as "Cn" (undefined).
1223    
1224        (c) I revised the way the table is implemented to a much improved format
1225            which includes recognition of ranges. It now supports the ranges that
1226            are defined in UnicodeData.txt, and it also amalgamates other
1227            characters into ranges. This has reduced the number of entries in the
1228            table from around 16,000 to around 3,000, thus reducing its size
1229            considerably. I realized I did not need to use a tree structure after
1230            all - a binary chop search is just as efficient. Having reduced the
1231            number of entries, I extended their size from 6 bytes to 8 bytes to
1232            allow for more data.
1233    
1234        (d) Added support for Unicode script names via properties such as \p{Han}.
1235    
1236    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1237        matching that character.
1238    
1239    20. When matching a repeated Unicode property with a minimum greater than zero,
1240        (for example \pL{2,}), PCRE could look past the end of the subject if it
1241        reached it while seeking the minimum number of characters. This could
1242        happen only if some of the characters were more than one byte long, because
1243        there is a check for at least the minimum number of bytes.
1244    
1245    21. Refactored the implementation of \p and \P so as to be more general, to
1246        allow for more different types of property in future. This has changed the
1247        compiled form incompatibly. Anybody with saved compiled patterns that use
1248        \p or \P will have to recompile them.
1249    
1250    22. Added "Any" and "L&" to the supported property types.
1251    
1252    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1253        but give a compile time error if the value is greater than 0xff.
1254    
1255    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1256        accidentally not being installed or uninstalled.
1257    
1258    25. The pcre.h file was built from pcre.h.in, but the only changes that were
1259        made were to insert the current release number. This seemed silly, because
1260        it made things harder for people building PCRE on systems that don't run
1261        "configure". I have turned pcre.h into a distributed file, no longer built
1262        by "configure", with the version identification directly included. There is
1263        no longer a pcre.h.in file.
1264    
1265        However, this change necessitated a change to the pcre-config script as
1266        well. It is built from pcre-config.in, and one of the substitutions was the
1267        release number. I have updated configure.ac so that ./configure now finds
1268        the release number by grepping pcre.h.
1269    
1270    26. Added the ability to run the tests under valgrind.
1271    
1272    
1273    Version 6.4 05-Sep-05
1274    ---------------------
1275    
1276     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1277        "--" to be printed when multiple files were scanned, even when none of the
1278        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1279        consider it to be a bug, and have restored the previous behaviour.
1280    
1281     2. A couple of code tidies to get rid of compiler warnings.
1282    
1283     3. The pcretest program used to cheat by referring to symbols in the library
1284        whose names begin with _pcre_. These are internal symbols that are not
1285        really supposed to be visible externally, and in some environments it is
1286        possible to suppress them. The cheating is now confined to including
1287        certain files from the library's source, which is a bit cleaner.
1288    
1289     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1290        file's purpose clearer.
1291    
1292     5. Reorganized pcre_ucp_findchar().
1293    
1294    
1295    Version 6.3 15-Aug-05
1296    ---------------------
1297    
1298     1. The file libpcre.pc.in did not have general read permission in the tarball.
1299    
1300     2. There were some problems when building without C++ support:
1301    
1302        (a) If C++ support was not built, "make install" and "make test" still
1303            tried to test it.
1304    
1305        (b) There were problems when the value of CXX was explicitly set. Some
1306            changes have been made to try to fix these, and ...
1307    
1308        (c) --disable-cpp can now be used to explicitly disable C++ support.
1309    
1310        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1311            backslash in a target when C++ was disabled. This confuses some
1312            versions of "make", apparently. Using an intermediate variable solves
1313            this. (Same for CPP_LOBJ.)
1314    
1315     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1316        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1317        necessary on certain architectures.
1318    
1319     4. Added a setting of -export-symbols-regex to the link command to remove
1320        those symbols that are exported in the C sense, but actually are local
1321        within the library, and not documented. Their names all begin with
1322        "_pcre_". This is not a perfect job, because (a) we have to except some
1323        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1324        available (and never for static libraries). I have made a note to try to
1325        find a way round (a) in the future.
1326    
1327    
1328    Version 6.2 01-Aug-05
1329    ---------------------
1330    
1331     1. There was no test for integer overflow of quantifier values. A construction
1332        such as {1111111111111111} would give undefined results. What is worse, if
1333        a minimum quantifier for a parenthesized subpattern overflowed and became
1334        negative, the calculation of the memory size went wrong. This could have
1335        led to memory overwriting.
1336    
1337     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1338    
1339     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1340        operating environments where this matters.
1341    
1342     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1343        PCRE options from within the C++ wrapper.
1344    
1345     5. Named capturing subpatterns were not being correctly counted when a pattern
1346        was compiled. This caused two problems: (a) If there were more than 100
1347        such subpatterns, the calculation of the memory needed for the whole
1348        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1349        back references of the form \12, where the number was greater than 9, were
1350        not recognized as back references, even though there were sufficient
1351        previous subpatterns.
1352    
1353     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1354        versions of gcc, e.g. 2.95.4.
1355    
1356    
1357    Version 6.1 21-Jun-05
1358    ---------------------
1359    
1360     1. There was one reference to the variable "posix" in pcretest.c that was not
1361        surrounded by "#if !defined NOPOSIX".
1362    
1363     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1364        the cross-check on the old pcre_info() function, for the benefit of the
1365        cut-down version of PCRE that is currently imported into Exim.
1366    
1367     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1368        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1369        patterns that start (?i) but I don't think that matters. The use of (?i) is
1370        just an example; this all applies to the other options as well.
1371    
1372     4. Since libtool seems to echo the compile commands it is issuing, the output
1373        from "make" can be reduced a bit by putting "@" in front of each libtool
1374        compile command.
1375    
1376     5. Patch from the folks at Google for configure.in to be a bit more thorough
1377        in checking for a suitable C++ installation before trying to compile the
1378        C++ stuff. This should fix a reported problem when a compiler was present,
1379        but no suitable headers.
1380    
1381     6. The man pages all had just "PCRE" as their title. I have changed them to
1382        be the relevant file name. I have also arranged that these names are
1383        retained in the file doc/pcre.txt, which is a concatenation in text format
1384        of all the man pages except the little individual ones for each function.
1385    
1386     7. The NON-UNIX-USE file had not been updated for the different set of source
1387        files that come with release 6. I also added a few comments about the C++
1388        wrapper.
1389    
1390    
1391    Version 6.0 07-Jun-05
1392    ---------------------
1393    
1394     1. Some minor internal re-organization to help with my DFA experiments.
1395    
1396     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1397        didn't matter for the library itself when fully configured, but did matter
1398        when compiling without UCP support, or within Exim, where the ucp files are
1399        not imported.
1400    
1401     3. Refactoring of the library code to split up the various functions into
1402        different source modules. The addition of the new DFA matching code (see
1403        below) to a single monolithic source would have made it really too
1404        unwieldy, quite apart from causing all the code to be include in a
1405        statically linked application, when only some functions are used. This is
1406        relevant even without the DFA addition now that patterns can be compiled in
1407        one application and matched in another.
1408    
1409        The downside of splitting up is that there have to be some external
1410        functions and data tables that are used internally in different modules of
1411        the library but which are not part of the API. These have all had their
1412        names changed to start with "_pcre_" so that they are unlikely to clash
1413        with other external names.
1414    
1415     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1416        a different (DFA) algorithm. Although it is slower than the original
1417        function, it does have some advantages for certain types of matching
1418        problem.
1419    
1420     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1421        including restarting after a partial match.
1422    
1423     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1424        defined when compiling for Windows was sent to me. I have put it into the
1425        code, though I have no means of testing or verifying it.
1426    
1427     7. Added the pcre_refcount() auxiliary function.
1428    
1429     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1430        match before or at the first newline in the subject string. In pcretest,
1431        the /f option on a pattern can be used to set this.
1432    
1433     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1434        would behave wrongly. This has been present in PCRE since release 4.0.
1435    
1436    10. A number of changes to the pcregrep command:
1437    
1438        (a) Refactored how -x works; insert ^(...)$ instead of setting
1439            PCRE_ANCHORED and checking the length, in preparation for adding
1440            something similar for -w.
1441    
1442        (b) Added the -w (match as a word) option.
1443    
1444        (c) Refactored the way lines are read and buffered so as to have more
1445            than one at a time available.
1446    
1447        (d) Implemented a pcregrep test script.
1448    
1449        (e) Added the -M (multiline match) option. This allows patterns to match
1450            over several lines of the subject. The buffering ensures that at least
1451            8K, or the rest of the document (whichever is the shorter) is available
1452            for matching (and similarly the previous 8K for lookbehind assertions).
1453    
1454        (f) Changed the --help output so that it now says
1455    
1456              -w, --word-regex(p)
1457    
1458            instead of two lines, one with "regex" and the other with "regexp"
1459            because that confused at least one person since the short forms are the
1460            same. (This required a bit of code, as the output is generated
1461            automatically from a table. It wasn't just a text change.)
1462    
1463        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1464            option but starts with a hyphen. Could be a pattern or a path name
1465            starting with a hyphen, for instance.
1466    
1467        (h) "-" can be given as a file name to represent stdin.
1468    
1469        (i) When file names are being printed, "(standard input)" is used for
1470            the standard input, for compatibility with GNU grep. Previously
1471            "<stdin>" was used.
1472    
1473        (j) The option --label=xxx can be used to supply a name to be used for
1474            stdin when file names are being printed. There is no short form.
1475    
1476        (k) Re-factored the options decoding logic because we are going to add
1477            two more options that take data. Such options can now be given in four
1478            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1479    
1480        (l) Added the -A, -B, and -C options for requesting that lines of context
1481            around matches be printed.
1482    
1483        (m) Added the -L option to print the names of files that do not contain
1484            any matching lines, that is, the complement of -l.
1485    
1486        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1487            continue to scan other files.
1488    
1489        (o) The -s option was incorrectly implemented. For compatibility with other
1490            greps, it now suppresses the error message for a non-existent or non-
1491            accessible file (but not the return code). There is a new option called
1492            -q that suppresses the output of matching lines, which was what -s was
1493            previously doing.
1494    
1495        (p) Added --include and --exclude options to specify files for inclusion
1496            and exclusion when recursing.
1497    
1498    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1499        Hopefully, it now does.
1500    
1501    12. Missing cast in pcre_study().
1502    
1503    13. Added an "uninstall" target to the makefile.
1504    
1505    14. Replaced "extern" in the function prototypes in Makefile.in with
1506        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1507        world, but is set differently for Windows.
1508    
1509    15. Added a second compiling function called pcre_compile2(). The only
1510        difference is that it has an extra argument, which is a pointer to an
1511        integer error code. When there is a compile-time failure, this is set
1512        non-zero, in addition to the error test pointer being set to point to an
1513        error message. The new argument may be NULL if no error number is required
1514        (but then you may as well call pcre_compile(), which is now just a
1515        wrapper). This facility is provided because some applications need a
1516        numeric error indication, but it has also enabled me to tidy up the way
1517        compile-time errors are handled in the POSIX wrapper.
1518    
1519    16. Added VPATH=.libs to the makefile; this should help when building with one
1520        prefix path and installing with another. (Or so I'm told by someone who
1521        knows more about this stuff than I do.)
1522    
1523    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1524        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1525        match everything, including newlines. This is not POSIX-compatible, but
1526        somebody wanted the feature. From pcretest it can be activated by using
1527        both the P and the s flags.
1528    
1529    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1530    
1531    19. libpcre.pc was being incorrectly installed as executable.
1532    
1533    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1534        it now also looks for '\r' so that it will work unmodified on Windows.
1535    
1536    21. Added Google's contributed C++ wrapper to the distribution.
1537    
1538    22. Added some untidy missing memory free() calls in pcretest, to keep
1539        Electric Fence happy when testing.
1540    
1541    
1542    
1543    Version 5.0 13-Sep-04
1544    ---------------------
1545    
1546     1. Internal change: literal characters are no longer packed up into items
1547        containing multiple characters in a single byte-string. Each character
1548        is now matched using a separate opcode. However, there may be more than one
1549        byte in the character in UTF-8 mode.
1550    
1551     2. The pcre_callout_block structure has two new fields: pattern_position and
1552        next_item_length. These contain the offset in the pattern to the next match
1553        item, and its length, respectively.
1554    
1555     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1556        insertion of callouts before each pattern item. Added the /C option to
1557        pcretest to make use of this.
1558    
1559     4. On the advice of a Windows user, the lines
1560    
1561          #if defined(_WIN32) || defined(WIN32)
1562          _setmode( _fileno( stdout ), 0x8000 );
1563          #endif  /* defined(_WIN32) || defined(WIN32) */
1564    
1565        have been added to the source of pcretest. This apparently does useful
1566        magic in relation to line terminators.
1567    
1568     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1569        for the benefit of those environments where the "b" makes a difference.
1570    
1571     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1572        to know about it. I have put a hack into configure.in that adds in code
1573        to set GCC=yes if CC=icc. This seems to end up at a point in the
1574        generated configure script that is early enough to affect the setting of
1575        compiler options, which is what is needed, but I have no means of testing
1576        whether it really works. (The user who reported this had patched the
1577        generated configure script, which of course I cannot do.)
1578    
1579        LATER: After change 22 below (new libtool files), the configure script
1580        seems to know about icc (and also ecc). Therefore, I have commented out
1581        this hack in configure.in.
1582    
1583     7. Added support for pkg-config (2 patches were sent in).
1584    
1585     8. Negated POSIX character classes that used a combination of internal tables
1586        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1587        [[:^ascii]]. Typically, they would match almost any characters. The other
1588        POSIX classes were not broken in this way.
1589    
1590     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1591        to find the match, as PCRE was deluded into thinking that the match had to
1592        start at the start point or following a newline. The same bug applied to
1593        patterns with negative forward assertions or any backward assertions
1594        preceding ".*" at the start, unless the pattern required a fixed first
1595        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1596    
1597    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1598        starting at the last subject character, bytes beyond the end of the subject
1599        string were read.
1600    
1601    11. Renamed the variable "class" as "classbits" to make life easier for C++
1602        users. (Previously there was a macro definition, but it apparently wasn't
1603        enough.)
1604    
1605    12. Added the new field "tables" to the extra data so that tables can be passed
1606        in at exec time, or the internal tables can be re-selected. This allows
1607        a compiled regex to be saved and re-used at a later time by a different
1608        program that might have everything at different addresses.
1609    
1610    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1611        -R library as well as a -L library.
1612    
1613    14. The debugging options of pcretest (-d on the command line or D on a
1614        pattern) showed incorrect output for anything following an extended class
1615        that contained multibyte characters and which was followed by a quantifier.
1616    
1617    15. Added optional support for general category Unicode character properties
1618        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1619        support. It adds about 90K to the size of the library. The meanings of the
1620        inbuilt class escapes such as \d and \s have NOT been changed.
1621    
1622    16. Updated pcredemo.c to include calls to free() to release the memory for the
1623        compiled pattern.
1624    
1625    17. The generated file chartables.c was being created in the source directory
1626        instead of in the building directory. This caused the build to fail if the
1627        source directory was different from the building directory, and was
1628        read-only.
1629    
1630    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1631        file. No doubt somebody will tell me if they don't make sense... Also added
1632        Dan Mooney's comments about building on OpenVMS.
1633    
1634    19. Added support for partial matching via the PCRE_PARTIAL option for
1635        pcre_exec() and the \P data escape in pcretest.
1636    
1637    20. Extended pcretest with 3 new pattern features:
1638    
1639        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1640              write the compiled pattern to the file whose name is "rest-of-line".
1641              This is a straight binary dump of the data, with the saved pointer to
1642              the character tables forced to be NULL. The study data, if any, is
1643              written too. After writing, pcretest reads a new pattern.
1644    
1645        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1646              compiled pattern from the given file. There must not be any
1647              occurrences of "<" in the file name (pretty unlikely); if there are,
1648              pcretest will instead treat the initial "<" as a pattern delimiter.
1649              After reading in the pattern, pcretest goes on to read data lines as
1650              usual.
1651    
1652        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1653              and 16-bit fields in a compiled pattern, to simulate a pattern that
1654              was compiled on a host of opposite endianness.
1655    
1656    21. The pcre-exec() function can now cope with patterns that were compiled on
1657        hosts of opposite endianness, with this restriction:
1658    
1659          As for any compiled expression that is saved and used later, the tables
1660          pointer field cannot be preserved; the extra_data field in the arguments
1661          to pcre_exec() should be used to pass in a tables address if a value
1662          other than the default internal tables were used at compile time.
1663    
1664    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1665        now diagnosed as an error. Previously, most of the time, a negative number
1666        would have been treated as zero, but if in addition "ovector" was passed as
1667        NULL, a crash could occur.
1668    
1669    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1670        new versions from the libtool 1.5 distribution (the last one is a copy of
1671        a file called libtool.m4). This seems to have fixed the need to patch
1672        "configure" to support Darwin 1.3 (which I used to do). However, I still
1673        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1674        workstation).
1675    
1676    24. Changed the PCRE licence to be the more standard "BSD" licence.
1677    
1678    
1679    Version 4.5 01-Dec-03
1680    ---------------------
1681    
1682     1. There has been some re-arrangement of the code for the match() function so
1683        that it can be compiled in a version that does not call itself recursively.
1684        Instead, it keeps those local variables that need separate instances for
1685        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1686        needs to "recurse". Keeping track of where control must go is done by means
1687        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1688        hide most of the details from the main code, and operates only if
1689        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1690        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1691        operating.
1692    
1693        To make it easier for callers to provide specially tailored get/free
1694        functions for this usage, two new functions, pcre_stack_malloc, and
1695        pcre_stack_free, are used. They are always called in strict stacking order,
1696        and the size of block requested is always the same.
1697    
1698        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1699        PCRE has been compiled to use the stack or the heap for recursion. The
1700        -C option of pcretest uses this to show which version is compiled.
1701    
1702        A new data escape \S, is added to pcretest; it causes the amounts of store
1703        obtained and freed by both kinds of malloc/free at match time to be added
1704        to the output.
1705    
1706     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1707        what's available on my current Linux desktop machine.
1708    
1709     3. When matching a UTF-8 string, the test for a valid string at the start has
1710        been extended. If start_offset is not zero, PCRE now checks that it points
1711        to a byte that is the start of a UTF-8 character. If not, it returns
1712        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1713        this is necessary because there may be backward assertions in the pattern.
1714        When matching the same subject several times, it may save resources to use
1715        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1716    
1717     4. The code for checking the validity of UTF-8 strings has been tightened so
1718        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1719        containing "overlong sequences".
1720    
1721     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1722        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1723        should have been "&", but it just so happened that all the cases this let
1724        through by mistake were picked up later in the function.
1725    
1726     6. I had used a variable called "isblank" - this is a C99 function, causing
1727        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1728    
1729     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1730        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1731        so the version is shown; (c) stop "make test" echoing "./RunTest".
1732    
1733     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1734    
1735     9. The prototype for memmove() for systems that don't have it was using
1736        size_t, but the inclusion of the header that defines size_t was later. I've
1737        moved the #includes for the C headers earlier to avoid this.
1738    
1739    10. Added some adjustments to the code to make it easier to compiler on certain
1740        special systems:
1741    
1742          (a) Some "const" qualifiers were missing.
1743          (b) Added the macro EXPORT before all exported functions; by default this
1744              is defined to be empty.
1745          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1746              that it reads its output file name as an argument instead of writing
1747              to the standard output and assuming this can be redirected.
1748    
1749    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1750        class containing characters with values greater than 255, PCRE compilation
1751        went into a loop.
1752    
1753    12. A recursive reference to a subpattern that was within another subpattern
1754        that had a minimum quantifier of zero caused PCRE to crash. For example,
1755        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1756        recursion. If the recursively-called subpattern itself had a zero repeat,
1757        that was OK.
1758    
1759    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1760        buffer into which it was copied (for escape processing) was still set at
1761        1024, so long lines caused crashes.
1762    
1763    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1764        "internal error: code overflow...". This applied to any character class
1765        that was followed by a possessive quantifier.
1766    
1767    15. Modified the Makefile to add libpcre.la as a prerequisite for
1768        libpcreposix.la because I was told this is needed for a parallel build to
1769        work.
1770    
1771    16. If a pattern that contained .* following optional items at the start was
1772        studied, the wrong optimizing data was generated, leading to matching
1773        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1774        matching string must start with a or b or c. The correct conclusion for
1775        this pattern is that a match can start with any character.
1776    
1777    
1778    Version 4.4 13-Aug-03
1779    ---------------------
1780    
1781     1. In UTF-8 mode, a character class containing characters with values between
1782        127 and 255 was not handled correctly if the compiled pattern was studied.
1783        In fixing this, I have also improved the studying algorithm for such
1784        classes (slightly).
1785    
1786     2. Three internal functions had redundant arguments passed to them. Removal
1787        might give a very teeny performance improvement.
1788    
1789     3. Documentation bug: the value of the capture_top field in a callout is *one
1790        more than* the number of the hightest numbered captured substring.
1791    
1792     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1793        in incorrectly linking with a previously installed version. They now link
1794        explicitly with libpcre.la.
1795    
1796     5. configure.in no longer needs to recognize Cygwin specially.
1797    
1798     6. A problem in pcre.in for Windows platforms is fixed.
1799    
1800     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1801        pcretest, it used to include the size of the study block as part of its
1802        output. Unfortunately, the structure contains a field that has a different
1803        size on different hardware architectures. This meant that the tests that
1804        showed this size failed. As the block is currently always of a fixed size,
1805        this information isn't actually particularly useful in pcretest output, so
1806        I have just removed it.
1807    
1808     8. Three pre-processor statements accidentally did not start in column 1.
1809        Sadly, there are *still* compilers around that complain, even though
1810        standard C has not required this for well over a decade. Sigh.
1811    
1812     9. In pcretest, the code for checking callouts passed small integers in the
1813        callout_data field, which is a void * field. However, some picky compilers
1814        complained about the casts involved for this on 64-bit systems. Now
1815        pcretest passes the address of the small integer instead, which should get
1816        rid of the warnings.
1817    
1818    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1819        both compile and run time, and gives an error if an invalid UTF-8 sequence
1820        is found. There is a option for disabling this check in cases where the
1821        string is known to be correct and/or the maximum performance is wanted.
1822    
1823    11. In response to a bug report, I changed one line in Makefile.in from
1824    
1825            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1826        to
1827            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1828    
1829        to look similar to other lines, but I have no way of telling whether this
1830        is the right thing to do, as I do not use Windows. No doubt I'll get told
1831        if it's wrong...
1832    
1833    
1834    Version 4.3 21-May-03
1835    ---------------------
1836    
1837    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1838       Makefile.
1839    
1840    2. Some refactoring to improve the quality of the code:
1841    
1842       (i)   The utf8_table... variables are now declared "const".
1843    
1844       (ii)  The code for \cx, which used the "case flipping" table to upper case
1845             lower case letters, now just substracts 32. This is ASCII-specific,
1846             but the whole concept of \cx is ASCII-specific, so it seems
1847             reasonable.
1848    
1849       (iii) PCRE was using its character types table to recognize decimal and
1850             hexadecimal digits in the pattern. This is silly, because it handles
1851             only 0-9, a-f, and A-F, but the character types table is locale-
1852             specific, which means strange things might happen. A private
1853             table is now used for this - though it costs 256 bytes, a table is
1854             much faster than multiple explicit tests. Of course, the standard
1855             character types table is still used for matching digits in subject
1856             strings against \d.
1857    
1858       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1859             ending in _t are). So I've renamed it as ESC_tee.
1860    
1861    3. The first argument for regexec() in the POSIX wrapper should have been
1862       defined as "const".
1863    
1864    4. Changed pcretest to use malloc() for its buffers so that they can be
1865       Electric Fenced for debugging.
1866    
1867    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1868       to read one or more bytes before the start of the subject string. Often this
1869       had no effect on PCRE's behaviour, but in some circumstances it could
1870       provoke a segmentation fault.
1871    
1872    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1873       to try to read one or more bytes before the start of the subject string.
1874    
1875    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1876       UTF-8 support could misbehave in various ways if the subject string
1877       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1878       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1879       back over UTF-8 characters.)
1880    
1881    
1882    Version 4.2 14-Apr-03
1883    ---------------------
1884    
1885    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1886    
1887    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1888         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1889         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1890         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1891         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1892           and BUILD_EXEEXT
1893         Note: automatic setting of the BUILD variables is not yet working
1894         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1895           compile-time but not at link-time
1896         [LINK]: use for linking executables only
1897         make different versions for Windows and non-Windows
1898         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1899           libraries
1900         [LINK_FOR_BUILD]: new variable
1901         [OBJEXT]: use throughout
1902         [EXEEXT]: use throughout
1903         <winshared>: new target
1904         <wininstall>: new target
1905         <dftables.o>: use native compiler
1906         <dftables>: use native linker
1907         <install>: handle Windows platform correctly
1908         <clean>: ditto
1909         <check>: ditto
1910         copy DLL to top builddir before testing
1911    
1912       As part of these changes, -no-undefined was removed again. This was reported
1913       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1914       in any case.
1915    
1916    3. Some tidies to get rid of compiler warnings:
1917    
1918       . In the match_data structure, match_limit was an unsigned long int, whereas
1919         match_call_count was an int. I've made them both unsigned long ints.
1920    
1921       . In pcretest the fact that a const uschar * doesn't automatically cast to
1922         a void * provoked a warning.
1923    
1924       . Turning on some more compiler warnings threw up some "shadow" variables
1925         and a few more missing casts.
1926    
1927    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1928       option, a class that contained a single character with a value between 128
1929       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1930    
1931    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1932       option, a class that contained several characters, but with at least one
1933       whose value was between 128 and 255 caused PCRE to crash.
1934    
1935    
1936    Version 4.1 12-Mar-03
1937    ---------------------
1938    
1939    1. Compiling with gcc -pedantic found a couple of places where casts were
1940    needed, and a string in dftables.c that was longer than standard compilers are
1941    required to support.
1942    
1943    2. Compiling with Sun's compiler found a few more places where the code could
1944    be tidied up in order to avoid warnings.
1945    
1946    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1947    first of these names is deprecated in the latest Autoconf in favour of the name
1948    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1949    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1950    analogy I have changed it to CFLAGS_FOR_BUILD.
1951    
1952    4. Added -no-undefined to the linking command in the Makefile, because this is
1953    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1954    linking step for the pcreposix library.
1955    
1956    5. PCRE was failing to diagnose the case of two named groups with the same
1957    name.
1958    
1959    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1960    literal character that is needed in the subject for a match, and scans along to
1961    ensure that it is present before embarking on the full matching process. This
1962    saves time in cases of nested unlimited repeats that are never going to match.
1963    Problem: the scan can take a lot of time if the subject is very long (e.g.
1964    megabytes), thus penalizing straightforward matches. It is now done only if the
1965    amount of subject to be scanned is less than 1000 bytes.
1966    
1967    7. A lesser problem with the same optimization is that it was recording the
1968    first character of an anchored pattern as "needed", thus provoking a search
1969    right along the subject, even when the first match of the pattern was going to
1970    fail. The "needed" character is now not set for anchored patterns, unless it
1971    follows something in the pattern that is of non-fixed length. Thus, it still
1972    fulfils its original purpose of finding quick non-matches in cases of nested
1973    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1974    
1975    
1976    Version 4.0 17-Feb-03
1977    ---------------------
1978    
1979    1. If a comment in an extended regex that started immediately after a meta-item
1980    extended to the end of string, PCRE compiled incorrect data. This could lead to
1981    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1982    
1983    2. Moved to autoconf 2.53 and libtool 1.4.2.
1984    
1985    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1986    the special perltest8 script is no longer needed - all the tests can be run
1987    from a single perltest script.
1988    
1989    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1990    by \s. It has now been removed in PCRE. This means it isn't recognized as
1991    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1992    class [:space:] *does* include VT, thereby creating a mess.
1993    
1994    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1995    space and tab.
1996    
1997    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1998    its new features into the main test script, reducing the number of scripts.
1999    
2000    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
2001    were backward compatible, and made the (?i) apply to the whole pattern, as if
2002    /i were given. Now it behaves more logically, and applies the option setting
2003    only to what follows. PCRE has been changed to follow suit. However, if it
2004    finds options settings right at the start of the pattern, it extracts them into
2005    the global options, as before. Thus, they show up in the info data.
2006    
2007    8. Added support for the \Q...\E escape sequence. Characters in between are
2008    treated as literals. This is slightly different from Perl in that $ and @ are
2009    also handled as literals inside the quotes. In Perl, they will cause variable
2010    interpolation. Note the following examples:
2011    
2012        Pattern            PCRE matches      Perl matches
2013    
2014        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
2015        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
2016        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
2017    
2018    For compatibility with Perl, \Q...\E sequences are recognized inside character
2019    classes as well as outside them.
2020    
2021    9. Re-organized 3 code statements in pcretest to avoid "overflow in
2022    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
2023    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
2024    signed/unsigned warnings.
2025    
2026    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
2027    option for pcretest, so I've replaced it by a simple function that does just
2028    that job.
2029    
2030    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
2031    "pcregrep -".
2032    
2033    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
2034    Java package. This provides some syntactic sugar for simple cases of what my
2035    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
2036    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
2037    item, you can use this simplified notation. Note that only makes sense with
2038    greedy quantifiers. Consequently, the use of the possessive quantifier forces
2039    greediness, whatever the setting of the PCRE_UNGREEDY option.
2040    
2041    13. A change of greediness default within a pattern was not taking effect at
2042    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
2043    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
2044    was abstracted outside.
2045    
2046    14. PCRE now supports the \G assertion. It is true when the current matching
2047    position is at the start point of the match. This differs from \A when the
2048    starting offset is non-zero. Used with the /g option of pcretest (or similar
2049    code), it works in the same way as it does for Perl's /g option. If all
2050    alternatives of a regex begin with \G, the expression is anchored to the start
2051    match position, and the "anchored" flag is set in the compiled expression.
2052    
2053    15. Some bugs concerning the handling of certain option changes within patterns
2054    have been fixed. These applied to options other than (?ims). For example,
2055    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
2056    been the other way round. Some of this was related to change 7 above.
2057    
2058    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
2059    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
2060    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
2061    POSIX classes only within a class (e.g. /[[:alpha:]]/).
2062    
2063    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
2064    mode. Unlike ".", it always matches newline, whatever the setting of
2065    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
2066    assertions. Perl allows it, but it doesn't (in general) work because it can't
2067    calculate the length of the lookbehind. At least, that's the case for Perl
2068    5.8.0 - I've been told they are going to document that it doesn't work in
2069    future.
2070    
2071    18. Added an error diagnosis for escapes that PCRE does not support: these are
2072    \L, \l, \N, \P, \p, \U, \u, and \X.
2073    
2074    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
2075    reading past the end of the pattern in cases such as /[abcd/.
2076    
2077    20. PCRE was getting more memory than necessary for patterns with classes that
2078    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
2079    
2080    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
2081    compiling PCRE for use with Virtual Pascal.
2082    
2083    22. Small fix to the Makefile to make it work properly if the build is done
2084    outside the source tree.
2085    
2086    23. Added a new extension: a condition to go with recursion. If a conditional
2087    subpattern starts with (?(R) the "true" branch is used if recursion has
2088    happened, whereas the "false" branch is used only at the top level.
2089    
2090    24. When there was a very long string of literal characters (over 255 bytes
2091    without UTF support, over 250 bytes with UTF support), the computation of how
2092    much memory was required could be incorrect, leading to segfaults or other
2093    strange effects.
2094    
2095    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
2096    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
2097    there was a subsequent back reference to those brackets. This meant that, for
2098    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
2099    possible to check for precisely this case. All we can do is abandon the
2100    optimization if .* occurs inside capturing brackets when there are any back
2101    references whatsoever. (See below for a better fix that came later.)
2102    
2103    26. The handling of the optimization for finding the first character of a
2104    non-anchored pattern, and for finding a character that is required later in the
2105    match were failing in some cases. This didn't break the matching; it just
2106    failed to optimize when it could. The way this is done has been re-implemented.
2107    
2108    27. Fixed typo in error message for invalid (?R item (it said "(?p").
2109    
2110    28. Added a new feature that provides some of the functionality that Perl
2111    provides with (?{...}). The facility is termed a "callout". The way it is done
2112    in PCRE is for the caller to provide an optional function, by setting
2113    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
2114    global variable. By default it is unset, which disables all calling out. To get
2115    the function called, the regex must include (?C) at appropriate points. This
2116    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
2117    This provides a means of identifying different callout points. When PCRE
2118    reaches such a point in the regex, if pcre_callout has been set, the external
2119    function is called. It is provided with data in a structure called
2120    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
2121    matching continues; if it returns a non-zero value, the match at the current
2122    point fails. However, backtracking will occur if possible. [This was changed
2123    later and other features added - see item 49 below.]
2124    
2125    29. pcretest is upgraded to test the callout functionality. It provides a
2126    callout function that displays information. By default, it shows the start of
2127    the match and the current position in the text. There are some new data escapes
2128    to vary what happens:
2129    
2130        \C+         in addition, show current contents of captured substrings
2131        \C-         do not supply a callout function
2132        \C!n        return 1 when callout number n is reached
2133        \C!n!m      return 1 when callout number n is reached for the mth time
2134    
2135    30. If pcregrep was called with the -l option and just a single file name, it
2136    output "<stdin>" if a match was found, instead of the file name.
2137    
2138    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
2139    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
2140    pcre_exec(). This saves a malloc/free per call. The default value of
2141    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
2142    when configuring.
2143    
2144    32. The default maximum size of a compiled pattern is 64K. There have been a
2145    few cases of people hitting this limit. The code now uses macros to handle the
2146    storing of links as offsets within the compiled pattern. It defaults to 2-byte
2147    links, but this can be changed to 3 or 4 bytes by --with-link-size when
2148    configuring. Tests 2 and 5 work only with 2-byte links because they output
2149    debugging information about compiled patterns.
2150    
2151    33. Internal code re-arrangements:
2152    
2153    (a) Moved the debugging function for printing out a compiled regex into
2154        its own source file (printint.c) and used #include to pull it into
2155        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
2156        separate copies.
2157    
2158    (b) Defined the list of op-code names for debugging as a macro in
2159        internal.h so that it is next to the definition of the opcodes.
2160    
2161    (c) Defined a table of op-code lengths for simpler skipping along compiled
2162        code. This is again a macro in internal.h so that it is next to the
2163        definition of the opcodes.
2164    
2165    34. Added support for recursive calls to individual subpatterns, along the
2166    lines of Robin Houston's patch (but implemented somewhat differently).
2167    
2168    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
2169    allow it to read and process whole directories in Win32. This code was
2170    contributed by Lionel Fourquaux; it has not been tested by me.
2171    
2172    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
2173    used to name a group. Names consist of alphanumerics and underscores, and must
2174    be unique. Back references use the syntax (?P=name) and recursive calls use
2175    (?P>name) which is a PCRE extension to the Python extension. Groups still have
2176    numbers. The function pcre_fullinfo() can be used after compilation to extract
2177    a name/number map. There are three relevant calls:
2178    
2179      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
2180      PCRE_INFO_NAMECOUNT            yields the number of entries
2181      PCRE_INFO_NAMETABLE            yields a pointer to the map.
2182    
2183    The map is a vector of fixed-size entries. The size of each entry depends on
2184    the length of the longest name used. The first two bytes of each entry are the
2185    group number, most significant byte first. There follows the corresponding
2186    name, zero terminated. The names are in alphabetical order.
2187    
2188    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
2189    case instead of 255. Making it the same both with and without UTF-8 support
2190    means that the same test output works with both.
2191    
2192    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
2193    calling malloc() with a zero argument.
2194    
2195    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
2196    optimization. I've improved things by keeping a bitmap of backreferences with
2197    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
2198    fact referenced, the optimization can be applied. It is unlikely that a
2199    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
2200    the match to follow \n) will appear inside brackets with a number greater than
2201    31, but if it does, any back reference > 31 suppresses the optimization.
2202    
2203    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
2204    of disabling numbered capturing parentheses. Any opening parenthesis that is
2205    not followed by ? behaves as if it were followed by ?: but named parentheses
2206    can still be used for capturing (and they will acquire numbers in the usual
2207    way).
2208    
2209    41. Redesigned the return codes from the match() function into yes/no/error so
2210    that errors can be passed back from deep inside the nested calls. A malloc
2211    failure while inside a recursive subpattern call now causes the
2212    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
2213    
2214    42. It is now possible to set a limit on the number of times the match()
2215    function is called in a call to pcre_exec(). This facility makes it possible to
2216    limit the amount of recursion and backtracking, though not in a directly
2217    obvious way, because the match() function is used in a number of different
2218    circumstances. The count starts from zero for each position in the subject
2219    string (for non-anchored patterns). The default limit is, for compatibility, a
2220    large number, namely 10 000 000. You can change this in two ways:
2221    
2222    (a) When configuring PCRE before making, you can use --with-match-limit=n
2223        to set a default value for the compiled library.
2224    
2225    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
2226        a different value is set. See 45 below.
2227    
2228    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
2229    
2230    43. Added a new function pcre_config(int, void *) to enable run-time extraction
2231    of things that can be changed at compile time. The first argument specifies
2232    what is wanted and the second points to where the information is to be placed.
2233    The current list of available information is:
2234    
2235      PCRE_CONFIG_UTF8
2236    
2237    The output is an integer that is set to one if UTF-8 support is available;
2238    otherwise it is set to zero.
2239    
2240      PCRE_CONFIG_NEWLINE
2241    
2242    The output is an integer that it set to the value of the code that is used for
2243    newline. It is either LF (10) or CR (13).
2244    
2245      PCRE_CONFIG_LINK_SIZE
2246    
2247    The output is an integer that contains the number of bytes used for internal
2248    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
2249    
2250      PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
2251    
2252    The output is an integer that contains the threshold above which the POSIX
2253    interface uses malloc() for output vectors. See item 31 above.
2254    
2255      PCRE_CONFIG_MATCH_LIMIT
2256    
2257    The output is an unsigned integer that contains the default limit of the number
2258    of match() calls in a pcre_exec() execution. See 42 above.
2259    
2260    44. pcretest has been upgraded by the addition of the -C option. This causes it
2261    to extract all the available output from the new pcre_config() function, and to
2262    output it. The program then exits immediately.
2263    
2264    45. A need has arisen to pass over additional data with calls to pcre_exec() in
2265    order to support additional features. One way would have been to define
2266    pcre_exec2() (for example) with extra arguments, but this would not have been
2267    extensible, and would also have required all calls to the original function to
2268    be mapped to the new one. Instead, I have chosen to extend the mechanism that
2269    is used for passing in "extra" data from pcre_study().
2270    
2271    The pcre_extra structure is now exposed and defined in pcre.h. It currently
2272    contains the following fields:
2273    
2274      flags         a bitmap indicating which of the following fields are set
2275      study_data    opaque data from pcre_study()
2276      match_limit   a way of specifying a limit on match() calls for a specific
2277                      call to pcre_exec()
2278      callout_data  data for callouts (see 49 below)
2279    
2280    The flag bits are also defined in pcre.h, and are
2281    
2282      PCRE_EXTRA_STUDY_DATA
2283      PCRE_EXTRA_MATCH_LIMIT
2284      PCRE_EXTRA_CALLOUT_DATA
2285    
2286    The pcre_study() function now returns one of these new pcre_extra blocks, with
2287    the actual study data pointed to by the study_data field, and the
2288    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
2289    before. That is, this change is entirely upwards-compatible and requires no
2290    change to existing code.
2291    
2292    If you want to pass in additional data to pcre_exec(), you can either place it
2293    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2294    block.
2295    
2296    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2297    data string contains the escape sequence \M, pcretest calls pcre_exec() several
2298    times with different match limits, until it finds the minimum value needed for
2299    pcre_exec() to complete. The value is then output. This can be instructive; for
2300    most simple matches the number is quite small, but for pathological cases it
2301    gets very large very quickly.
2302    
2303    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2304    returns the size of the data block pointed to by the study_data field in a
2305    pcre_extra block, that is, the value that was passed as the argument to
2306    pcre_malloc() when PCRE was getting memory in which to place the information
2307    created by pcre_study(). The fourth argument should point to a size_t variable.
2308    pcretest has been extended so that this information is shown after a successful
2309    pcre_study() call when information about the compiled regex is being displayed.
2310    
2311    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2312    because what follows is always an absolute path. (Later: it turns out that this
2313    is more than cosmetic for MinGW, because it doesn't like empty path
2314    components.)
2315    
2316    49. Some changes have been made to the callout feature (see 28 above):
2317    
2318    (i)  A callout function now has three choices for what it returns:
2319    
2320           0  =>  success, carry on matching
2321         > 0  =>  failure at this point, but backtrack if possible
2322         < 0  =>  serious error, return this value from pcre_exec()
2323    
2324         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2325         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2326         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2327         use by callout functions. It will never be used by PCRE itself.
2328    
2329    (ii) The pcre_extra structure (see 45 above) has a void * field called
2330         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2331         pcre_callout_block structure has a field of the same name. The contents of
2332         the field passed in the pcre_extra structure are passed to the callout
2333         function in the corresponding field in the callout block. This makes it
2334         easier to use the same callout-containing regex from multiple threads. For
2335         testing, the pcretest program has a new data escape
2336    
2337           \C*n        pass the number n (may be negative) as callout_data
2338    
2339         If the callout function in pcretest receives a non-zero value as
2340         callout_data, it returns that value.
2341    
2342    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2343    there were some redundant $(CFLAGS) in commands that are now specified as
2344    $(LINK), which already includes $(CFLAGS).
2345    
2346    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2347    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2348    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2349    one-byte characters throughout. Note that case-insensitive matching applies
2350    only to characters whose values are less than 256. PCRE doesn't support the
2351    notion of cases for higher-valued characters.
2352    
2353    (i)   A character class whose characters are all within 0-255 is handled as
2354          a bit map, and the map is inverted for negative classes. Previously, a
2355          character > 255 always failed to match such a class; however it should
2356          match if the class was a negative one (e.g. [^ab]). This has been fixed.
2357    
2358    (ii)  A negated character class with a single character < 255 is coded as
2359          "not this character" (OP_NOT). This wasn't working properly when the test
2360          character was multibyte, either singly or repeated.
2361    
2362    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2363          mode, for example: \x{100}{2,3}.
2364    
2365    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2366          singly or repeated) now correctly test multibyte characters. However,
2367          PCRE doesn't recognize any characters with values greater than 255 as
2368          digits, spaces, or word characters. Such characters always match \D, \S,
2369          and \W, and never match \d, \s, or \w.
2370    
2371    (v)   Classes may now contain characters and character ranges with values
2372          greater than 255. For example: [ab\x{100}-\x{400}].
2373    
2374    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
2375          PCRE in UTF-8 mode.
2376    
2377    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2378    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2379    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2380    value.)
2381    
2382    53. The single man page has become too large. I have therefore split it up into
2383    a number of separate man pages. These also give rise to individual HTML pages;
2384    these are now put in a separate directory, and there is an index.html page that
2385    lists them all. Some hyperlinking between the pages has been installed.
2386    
2387    54. Added convenience functions for handling named capturing parentheses.
2388    
2389    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2390    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2391    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2392    are faulted.
2393    
2394    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2395    calling configure. These values are used when compiling the dftables.c program
2396    which is run to generate the source of the default character tables. They
2397    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2398    you will need to set these values.
2399    
2400    57. Updated the building process for Windows DLL, as provided by Fred Cox.
2401    
2402    
2403    Version 3.9 02-Jan-02
2404    ---------------------
2405    
2406    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
2407    
2408    2. If --disable-static was given, the building process failed when trying to
2409    build pcretest and pcregrep. (For some reason it was using libtool to compile
2410    them, which is not right, as they aren't part of the library.)
2411    
2412    
2413    Version 3.8 18-Dec-01
2414    ---------------------
2415    
2416    1. The experimental UTF-8 code was completely screwed up. It was packing the
2417    bytes in the wrong order. How dumb can you get?
2418    
2419    
2420    Version 3.7 29-Oct-01
2421    ---------------------
2422    
2423    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
2424    This caused pcretest, when used on the test data, to segfault. Unfortunately,
2425    this didn't happen under Solaris 8, where I normally test things.
2426    
2427    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
2428    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
2429    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
2430    this fix an hour or so after the initial 3.7 release.)
2431    
2432    
2433    Version 3.6 23-Oct-01
2434    ---------------------
2435    
2436    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
2437    offsets passed as NULL with zero offset count.
2438    
2439    2. The config.guess and config.sub files had not been updated when I moved to
2440    the latest autoconf.
2441    
2442    
2443    Version 3.5 15-Aug-01
2444    ---------------------
2445    
2446    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2447    had been forgotten.
2448    
2449    2. By using declared but undefined structures, we can avoid using "void"
2450    definitions in pcre.h while keeping the internal definitions of the structures
2451    private.
2452    
2453    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2454    user point of view, this means that both static and shared libraries are built
2455    by default, but this can be individually controlled. More of the work of
2456    handling this static/shared cases is now inside libtool instead of PCRE's make
2457    file.
2458    
2459    4. The pcretest utility is now installed along with pcregrep because it is
2460    useful for users (to test regexs) and by doing this, it automatically gets
2461    relinked by libtool. The documentation has been turned into a man page, so
2462    there are now .1, .txt, and .html versions in /doc.
2463    
2464    5. Upgrades to pcregrep:
2465       (i)   Added long-form option names like gnu grep.
2466       (ii)  Added --help to list all options with an explanatory phrase.
2467       (iii) Added -r, --recursive to recurse into sub-directories.
2468       (iv)  Added -f, --file to read patterns from a file.
2469    
2470    6. pcre_exec() was referring to its "code" argument before testing that
2471    argument for NULL (and giving an error if it was NULL).
2472    
2473    7. Upgraded Makefile.in to allow for compiling in a different directory from
2474    the source directory.
2475    
2476    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2477    options bits, the pointer it was passed was to an int instead of to an unsigned
2478    long int. This mattered only on 64-bit systems.
2479    
2480    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2481    generated) instead of pcre.in, which it its source. Also made the same change
2482    in several of the .c files.
2483    
2484    10. A new release of gcc defines printf() as a macro, which broke pcretest
2485    because it had an ifdef in the middle of a string argument for printf(). Fixed
2486    by using separate calls to printf().
2487    
2488    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2489    script, to force use of CR or LF instead of \n in the source. On non-Unix
2490    systems, the value can be set in config.h.
2491    
2492    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2493    absolute limit. Changed the text of the error message to make this clear, and
2494    likewise updated the man page.
2495    
2496    13. The limit of 99 on the number of capturing subpatterns has been removed.
2497    The new limit is 65535, which I hope will not be a "real" limit.
2498    
2499    
2500    Version 3.4 22-Aug-00
2501    ---------------------
2502    
2503    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2504    
2505    2. Diagnose condition (?(0) as an error instead of crashing on matching.
2506    
2507    
2508    Version 3.3 01-Aug-00
2509    ---------------------
2510    
2511    1. If an octal character was given, but the value was greater than \377, it
2512    was not getting masked to the least significant bits, as documented. This could
2513    lead to crashes in some systems.
2514    
2515    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2516    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2517    
2518    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2519    These just pass their arguments on to (pcre_free)(), but they are provided
2520    because some uses of PCRE bind it to non-C systems that can call its functions,
2521    but cannot call free() or pcre_free() directly.
2522    
2523    4. Add "make test" as a synonym for "make check". Corrected some comments in
2524    the Makefile.
2525    
2526    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2527    Makefile.
2528    
2529    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2530    command called pgrep for grepping around the active processes.
2531    
2532    7. Added the beginnings of support for UTF-8 character strings.
2533    
2534    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2535    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2536    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2537    out for the ar command.)
2538    
2539    
2540    Version 3.2 12-May-00
2541    ---------------------
2542    
2543    This is purely a bug fixing release.
2544    
2545    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
2546    of ZA. This was just one example of several cases that could provoke this bug,
2547    which was introduced by change 9 of version 2.00. The code for breaking
2548    infinite loops after an iteration that matches an empty string was't working
2549    correctly.
2550    
2551    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
2552    when matched against abbab (for example). After matching an empty string, it
2553    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
2554    caused it to match further down the string than it should.
2555    
2556    3. The code contained an inclusion of sys/types.h. It isn't clear why this
2557    was there because it doesn't seem to be needed, and it causes trouble on some
2558    systems, as it is not a Standard C header. It has been removed.
2559    
2560    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
2561    were reported on the Macintosh. The changes were from
2562    
2563      while ((c = *(++ptr)) != 0 && c != '\n');
2564    to
2565      while ((c = *(++ptr)) != 0 && c != '\n') ;
2566    
2567    Totally extraordinary, but if that's what it takes...
2568    
2569    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2570    available. Added HAVE_BCOPY and an autoconf test for it; if neither
2571    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2572    assumes the way PCRE uses memmove() (always moving upwards).
2573    
2574    6. PCRE is being used in one environment where strchr() is not available. There
2575    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2576    faster code anyway.
2577    
2578    
2579    Version 3.1 09-Feb-00
2580    ---------------------
2581    
2582    The only change in this release is the fixing of some bugs in Makefile.in for
2583    the "install" target:
2584    
2585    (1) It was failing to install pcreposix.h.
2586    
2587    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2588    
2589  Version 2.09 14-Sep-99  
2590  ----------------------  Version 3.0 01-Feb-00
2591    ---------------------
2592    
2593  1. Add support for the /+ modifier to perltest (to output $` like it does in  1. Add support for the /+ modifier to perltest (to output $` like it does in
2594  pcretest).  pcretest).
# Line 23  captured string vector to pcre_exec(), b Line 2608  captured string vector to pcre_exec(), b
2608  required a bigger vector, with some working space on the end. This means that  required a bigger vector, with some working space on the end. This means that
2609  the POSIX wrapper now has to get and free some memory, and copy the results.  the POSIX wrapper now has to get and free some memory, and copy the results.
2610    
2611    6. Added some simple autoconf support, placing the test data and the
2612    documentation in separate directories, re-organizing some of the
2613    information files, and making it build pcre-config (a GNU standard). Also added
2614    libtool support for building PCRE as a shared library, which is now the
2615    default.
2616    
2617    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2618    09 are not valid octal constants. Single digits will be used for minor values
2619    less than 10.
2620    
2621    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2622    existing programs that set these in the POSIX interface can use PCRE without
2623    modification.
2624    
2625    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2626    return all that pcre_info() returns, plus additional data. The pcre_info()
2627    function is retained for compatibility, but is considered to be obsolete.
2628    
2629    10. Added experimental recursion feature (?R) to handle one common case that
2630    Perl 5.6 will be able to do with (?p{...}).
2631    
2632    11. Added support for POSIX character classes like [:alpha:], which Perl is
2633    adopting.
2634    
2635    
2636  Version 2.08 31-Aug-99  Version 2.08 31-Aug-99
2637  ----------------------  ----------------------

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