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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 7.3 09-Aug-07
5    ---------------------
6    
7     1. In the rejigging of the build system that eventually resulted in 7.1, the
8        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
9        brackets there is not right, since it causes compilers to look for an
10        installed pcre.h, not the version that is in the source that is being
11        compiled (which of course may be different). I have changed it back to:
12    
13          #include "pcre.h"
14    
15        I have a vague recollection that the change was concerned with compiling in
16        different directories, but in the new build system, that is taken care of
17        by the VPATH setting the Makefile.
18    
19     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
20        when the subject happened to end in the byte 0x85 (e.g. if the last
21        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
22        characters but of course it shouldn't be taken as a newline when it is part
23        of another character. The bug was that, for an unlimited repeat of . in
24        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
25        characters when looking for a newline.
26    
27     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
28    
29     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
30        in debug output.
31    
32     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
33        long printing in the pcrecpp unittest when running under MinGW.
34    
35     6. ESC_K was left out of the EBCDIC table.
36    
37     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
38        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
39        limit also applies to "virtual nesting" when a pattern is recursive, and in
40        this case 1000 isn't so big. I have been able to remove this limit at the
41        expense of backing off one optimization in certain circumstances. Normally,
42        when pcre_exec() would call its internal match() function recursively and
43        immediately return the result unconditionally, it uses a "tail recursion"
44        feature to save stack. However, when a subpattern that can match an empty
45        string has an unlimited repetition quantifier, it no longer makes this
46        optimization. That gives it a stack frame in which to save the data for
47        checking that an empty string has been matched. Previously this was taken
48        from the 1000-entry workspace that had been reserved. So now there is no
49        explicit limit, but more stack is used.
50    
51     8. Applied Daniel's patches to solve problems with the import/export magic
52        syntax that is required for Windows, and which was going wrong for the
53        pcreposix and pcrecpp parts of the library. These were overlooked when this
54        problem was solved for the main library.
55    
56     9. There were some crude static tests to avoid integer overflow when computing
57        the size of patterns that contain repeated groups with explicit upper
58        limits. As the maximum quantifier is 65535, the maximum group length was
59        set at 30,000 so that the product of these two numbers did not overflow a
60        32-bit integer. However, it turns out that people want to use groups that
61        are longer than 30,000 bytes (though not repeat them that many times).
62        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
63        made it possible to implement the integer overflow checks in a much more
64        dynamic way, which I have now done. The artificial limitation on group
65        length has been removed - we now have only the limit on the total length of
66        the compiled pattern, which depends on the LINK_SIZE setting.
67    
68    10. Fixed a bug in the documentation for get/copy named substring when
69        duplicate names are permitted. If none of the named substrings are set, the
70        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
71        empty string.
72    
73    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
74        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
75        because the ] is interpreted as the first data character and the
76        terminating ] is not found. PCRE has been made compatible with Perl in this
77        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
78        cause memory overwriting.
79    
80    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
81        string has been matched (to stop an infinite loop). It was not recognizing
82        a conditional subpattern that could match an empty string if that
83        subpattern was within another subpattern. For example, it looped when
84        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
85        condition was not nested. This bug has been fixed.
86    
87    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
88        past the start of the subject in the presence of bytes with the top bit
89        set, for example "\x8aBCD".
90    
91    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
92        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
93    
94    14. Optimized (?!) to (*FAIL).
95    
96    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
97        This restricts code points to be within the range 0 to 0x10FFFF, excluding
98        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
99        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
100        does: it's just the validity check that is more restrictive.
101    
102    16. Inserted checks for integer overflows during escape sequence (backslash)
103        processing, and also fixed erroneous offset values for syntax errors during
104        backslash processing.
105    
106    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
107        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
108    
109    
110    Version 7.2 19-Jun-07
111    ---------------------
112    
113     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
114        which is apparently normally available under Windows.
115    
116     2. Re-jig the pcregrep tests with different newline settings in an attempt
117        to make them independent of the local environment's newline setting.
118    
119     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
120    
121     4. Some of the "internals" tests were previously cut out when the link size
122        was not 2, because the output contained actual offsets. The recent new
123        "Z" feature of pcretest means that these can be cut out, making the tests
124        usable with all link sizes.
125    
126     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
127        stack recursion. This gives a massive performance boost under BSD, but just
128        a small improvement under Linux. However, it saves one field in the frame
129        in all cases.
130    
131     6. Added more features from the forthcoming Perl 5.10:
132    
133        (a) (?-n) (where n is a string of digits) is a relative subroutine or
134            recursion call. It refers to the nth most recently opened parentheses.
135    
136        (b) (?+n) is also a relative subroutine call; it refers to the nth next
137            to be opened parentheses.
138    
139        (c) Conditions that refer to capturing parentheses can be specified
140            relatively, for example, (?(-2)... or (?(+3)...
141    
142        (d) \K resets the start of the current match so that everything before
143            is not part of it.
144    
145        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
146    
147        (f) \g{name} is another synonym - part of Perl 5.10's unification of
148            reference syntax.
149    
150        (g) (?| introduces a group in which the numbering of parentheses in each
151            alternative starts with the same number.
152    
153        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
154    
155     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
156        PCRE_INFO_JCHANGED.
157    
158     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
159        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
160        for detecting groups that can match an empty string.
161    
162     9. A pattern with a very large number of alternatives (more than several
163        hundred) was running out of internal workspace during the pre-compile
164        phase, where pcre_compile() figures out how much memory will be needed. A
165        bit of new cunning has reduced the workspace needed for groups with
166        alternatives. The 1000-alternative test pattern now uses 12 bytes of
167        workspace instead of running out of the 4096 that are available.
168    
169    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
170    
171    11. Applied patch from Google to remove an optimization that didn't quite work.
172        The report of the bug said:
173    
174          pcrecpp::RE("a*").FullMatch("aaa") matches, while
175          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
176          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
177    
178    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
179        it matched the wrong number of bytes.
180    
181    
182    Version 7.1 24-Apr-07
183    ---------------------
184    
185     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
186        that is more "standard", making use of automake and other Autotools. There
187        is some re-arrangement of the files and adjustment of comments consequent
188        on this.
189    
190     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
191        for recursive directory scanning broke on some systems because the files
192        are not scanned in any specific order and on different systems the order
193        was different. A call to "sort" has been inserted into RunGrepTest for the
194        approprate test as a short-term fix. In the longer term there may be an
195        alternative.
196    
197     3. I had an email from Eric Raymond about problems translating some of PCRE's
198        man pages to HTML (despite the fact that I distribute HTML pages, some
199        people do their own conversions for various reasons). The problems
200        concerned the use of low-level troff macros .br and .in. I have therefore
201        removed all such uses from the man pages (some were redundant, some could
202        be replaced by .nf/.fi pairs). The 132html script that I use to generate
203        HTML has been updated to handle .nf/.fi and to complain if it encounters
204        .br or .in.
205    
206     4. Updated comments in configure.ac that get placed in config.h.in and also
207        arranged for config.h to be included in the distribution, with the name
208        config.h.generic, for the benefit of those who have to compile without
209        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
210    
211     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
212        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
213        makevp.bat for the current PCRE, using the additional files
214        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
215    
216     6. A Windows user reported a minor discrepancy with test 2, which turned out
217        to be caused by a trailing space on an input line that had got lost in his
218        copy. The trailing space was an accident, so I've just removed it.
219    
220     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
221        that is needed.
222    
223     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
224        as "const" (a) because they are and (b) because it helps the PHP
225        maintainers who have recently made a script to detect big data structures
226        in the php code that should be moved to the .rodata section. I remembered
227        to update Builducptable as well, so it won't revert if ucptable.h is ever
228        re-created.
229    
230     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
231        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
232        order to be able to cut out the UTF-8 tables in the latter when UTF-8
233        support is not required. This saves 1.5-2K of code, which is important in
234        some applications.
235    
236        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
237        so as not to refer to the tables, even though these functions will never be
238        called when UTF-8 support is disabled. Otherwise there are problems with a
239        shared library.
240    
241    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
242    
243        (a) It was defining its arguments as char * instead of void *.
244    
245        (b) It was assuming that all moves were upwards in memory; this was true
246            a long time ago when I wrote it, but is no longer the case.
247    
248        The emulated memove() is provided for those environments that have neither
249        memmove() nor bcopy(). I didn't think anyone used it these days, but that
250        is clearly not the case, as these two bugs were recently reported.
251    
252    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
253        and Detrail to create the HTML documentation, the .txt form of the man
254        pages, and it removes trailing spaces from listed files. It also creates
255        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
256        case, it wraps all the #defines with #ifndefs. This script should be run
257        before "make dist".
258    
259    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
260        with Unicode property support.
261    
262        (a) For a maximizing quantifier, if the two different cases of the
263            character were of different lengths in their UTF-8 codings (there are
264            some cases like this - I found 11), and the matching function had to
265            back up over a mixture of the two cases, it incorrectly assumed they
266            were both the same length.
267    
268        (b) When PCRE was configured to use the heap rather than the stack for
269            recursion during matching, it was not correctly preserving the data for
270            the other case of a UTF-8 character when checking ahead for a match
271            while processing a minimizing repeat. If the check also involved
272            matching a wide character, but failed, corruption could cause an
273            erroneous result when trying to check for a repeat of the original
274            character.
275    
276    13. Some tidying changes to the testing mechanism:
277    
278        (a) The RunTest script now detects the internal link size and whether there
279            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
280            values substituted by "configure". (The RunGrepTest script already did
281            this for UTF-8.) The configure.ac script no longer substitutes the
282            relevant variables.
283    
284        (b) The debugging options /B and /D in pcretest show the compiled bytecode
285            with length and offset values. This means that the output is different
286            for different internal link sizes. Test 2 is skipped for link sizes
287            other than 2 because of this, bypassing the problem. Unfortunately,
288            there was also a test in test 3 (the locale tests) that used /B and
289            failed for link sizes other than 2. Rather than cut the whole test out,
290            I have added a new /Z option to pcretest that replaces the length and
291            offset values with spaces. This is now used to make test 3 independent
292            of link size. (Test 2 will be tidied up later.)
293    
294    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
295        segmentation fault instead of returning the appropriate error message.
296    
297    15. In multiline mode when the newline sequence was set to "any", the pattern
298        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
299        This doesn't seem right; it now treats the CRLF combination as the line
300        ending, and so does not match in that case. It's only a pattern such as ^$
301        that would hit this one: something like ^ABC$ would have failed after \r
302        and then tried again after \r\n.
303    
304    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
305        in an attempt to make files that differ only in their line terminators
306        compare equal. This works on Linux.
307    
308    17. Under certain error circumstances pcregrep might try to free random memory
309        as it exited. This is now fixed, thanks to valgrind.
310    
311    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
312        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
313        was because its rules for how to advance for /g after matching an empty
314        string at the end of a line did not allow for this case. They now check for
315        it specially.
316    
317    20. pcretest is supposed to handle patterns and data of any length, by
318        extending its buffers when necessary. It was getting this wrong when the
319        buffer for a data line had to be extended.
320    
321    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
322        CRLF as a newline sequence.
323    
324    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
325        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
326        I have nevertheless tidied it up.
327    
328    23. Added some casts to kill warnings from HP-UX ia64 compiler.
329    
330    24. Added a man page for pcre-config.
331    
332    
333    Version 7.0 19-Dec-06
334    ---------------------
335    
336     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
337        moving to gcc 4.1.1.
338    
339     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
340        sys/time.h, which is documented as needed for this function. It doesn't
341        seem to matter on Linux, but it showed up on some releases of OS X.
342    
343     3. It seems that there are systems where bytes whose values are greater than
344        127 match isprint() in the "C" locale. The "C" locale should be the
345        default when a C program starts up. In most systems, only ASCII printing
346        characters match isprint(). This difference caused the output from pcretest
347        to vary, making some of the tests fail. I have changed pcretest so that:
348    
349        (a) When it is outputting text in the compiled version of a pattern, bytes
350            other than 32-126 are always shown as hex escapes.
351    
352        (b) When it is outputting text that is a matched part of a subject string,
353            it does the same, unless a different locale has been set for the match
354            (using the /L modifier). In this case, it uses isprint() to decide.
355    
356     4. Fixed a major bug that caused incorrect computation of the amount of memory
357        required for a compiled pattern when options that changed within the
358        pattern affected the logic of the preliminary scan that determines the
359        length. The relevant options are -x, and -i in UTF-8 mode. The result was
360        that the computed length was too small. The symptoms of this bug were
361        either the PCRE error "internal error: code overflow" from pcre_compile(),
362        or a glibc crash with a message such as "pcretest: free(): invalid next
363        size (fast)". Examples of patterns that provoked this bug (shown in
364        pcretest format) are:
365    
366          /(?-x: )/x
367          /(?x)(?-x: \s*#\s*)/
368          /((?i)[\x{c0}])/8
369          /(?i:[\x{c0}])/8
370    
371        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
372        is now done differently.
373    
374     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
375        wrapper classes; (b) implement a new function in the C++ scanner that is
376        more efficient than the old way of doing things because it avoids levels of
377        recursion in the regex matching; (c) add a paragraph to the documentation
378        for the FullMatch() function.
379    
380     6. The escape sequence \n was being treated as whatever was defined as
381        "newline". Not only was this contrary to the documentation, which states
382        that \n is character 10 (hex 0A), but it also went horribly wrong when
383        "newline" was defined as CRLF. This has been fixed.
384    
385     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
386        was being set to -1 for the "end of line" case (supposedly a value that no
387        character can have). Though this value is never used (the check for end of
388        line is "zero bytes in current character"), it caused compiler complaints.
389        I've changed it to 0xffffffff.
390    
391     8. In pcre_version.c, the version string was being built by a sequence of
392        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
393        string (as it is for production releases) called a macro with an empty
394        argument. The C standard says the result of this is undefined. The gcc
395        compiler treats it as an empty string (which was what was wanted) but it is
396        reported that Visual C gives an error. The source has been hacked around to
397        avoid this problem.
398    
399     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
400        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
401        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
402        of them did).
403    
404    10. Originally, pcretest opened its input and output without "b"; then I was
405        told that "b" was needed in some environments, so it was added for release
406        5.0 to both the input and output. (It makes no difference on Unix-like
407        systems.) Later I was told that it is wrong for the input on Windows. I've
408        now abstracted the modes into two macros, to make it easier to fiddle with
409        them, and removed "b" from the input mode under Windows.
410    
411    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
412    
413    12. Added -help and --help to pcretest as an official way of being reminded
414        of the options.
415    
416    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
417        and pcrecpp.cc because they annoy compilers at high warning levels.
418    
419    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
420    
421    15. Fixed an occurrence of == in configure.ac that should have been = (shell
422        scripts are not C programs :-) and which was not noticed because it works
423        on Linux.
424    
425    16. pcretest is supposed to handle any length of pattern and data line (as one
426        line or as a continued sequence of lines) by extending its input buffer if
427        necessary. This feature was broken for very long pattern lines, leading to
428        a string of junk being passed to pcre_compile() if the pattern was longer
429        than about 50K.
430    
431    17. I have done a major re-factoring of the way pcre_compile() computes the
432        amount of memory needed for a compiled pattern. Previously, there was code
433        that made a preliminary scan of the pattern in order to do this. That was
434        OK when PCRE was new, but as the facilities have expanded, it has become
435        harder and harder to keep it in step with the real compile phase, and there
436        have been a number of bugs (see for example, 4 above). I have now found a
437        cunning way of running the real compile function in a "fake" mode that
438        enables it to compute how much memory it would need, while actually only
439        ever using a few hundred bytes of working memory and without too many
440        tests of the mode. This should make future maintenance and development
441        easier. A side effect of this work is that the limit of 200 on the nesting
442        depth of parentheses has been removed (though this was never a serious
443        limitation, I suspect). However, there is a downside: pcre_compile() now
444        runs more slowly than before (30% or more, depending on the pattern). I
445        hope this isn't a big issue. There is no effect on runtime performance.
446    
447    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
448        newline (only possible for the last line of a file) and it was a
449        pattern that set a locale (followed by /Lsomething), pcretest crashed.
450    
451    19. Added additional timing features to pcretest. (1) The -tm option now times
452        matching only, not compiling. (2) Both -t and -tm can be followed, as a
453        separate command line item, by a number that specifies the number of
454        repeats to use when timing. The default is 50000; this gives better
455        precision, but takes uncomfortably long for very large patterns.
456    
457    20. Extended pcre_study() to be more clever in cases where a branch of a
458        subpattern has no definite first character. For example, (a*|b*)[cd] would
459        previously give no result from pcre_study(). Now it recognizes that the
460        first character must be a, b, c, or d.
461    
462    21. There was an incorrect error "recursive call could loop indefinitely" if
463        a subpattern (or the entire pattern) that was being tested for matching an
464        empty string contained only one non-empty item after a nested subpattern.
465        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
466        incorrectly, because the \d was being skipped in the check.
467    
468    22. The pcretest program now has a new pattern option /B and a command line
469        option -b, which is equivalent to adding /B to every pattern. This causes
470        it to show the compiled bytecode, without the additional information that
471        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
472        is the same as /B/I).
473    
474    23. A new optimization is now able automatically to treat some sequences such
475        as a*b as a*+b. More specifically, if something simple (such as a character
476        or a simple class like \d) has an unlimited quantifier, and is followed by
477        something that cannot possibly match the quantified thing, the quantifier
478        is automatically "possessified".
479    
480    24. A recursive reference to a subpattern whose number was greater than 39
481        went wrong under certain circumstances in UTF-8 mode. This bug could also
482        have affected the operation of pcre_study().
483    
484    25. Realized that a little bit of performance could be had by replacing
485        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
486    
487    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
488    
489    27. Possessive quantifiers such as a++ were previously implemented by turning
490        them into atomic groups such as ($>a+). Now they have their own opcodes,
491        which improves performance. This includes the automatically created ones
492        from 23 above.
493    
494    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
495        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
496        the first matched character to be a colon. This applied both to named and
497        numbered groups.
498    
499    29. The ucpinternal.h header file was missing its idempotency #ifdef.
500    
501    30. I was sent a "project" file called libpcre.a.dev which I understand makes
502        building PCRE on Windows easier, so I have included it in the distribution.
503    
504    31. There is now a check in pcretest against a ridiculously large number being
505        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
506        loop, the loop is abandoned.
507    
508    32. Forward references to subpatterns in conditions such as (?(2)...) where
509        subpattern 2 is defined later cause pcre_compile() to search forwards in
510        the pattern for the relevant set of parentheses. This search went wrong
511        when there were unescaped parentheses in a character class, parentheses
512        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
513    
514    33. "Subroutine" calls and backreferences were previously restricted to
515        referencing subpatterns earlier in the regex. This restriction has now
516        been removed.
517    
518    34. Added a number of extra features that are going to be in Perl 5.10. On the
519        whole, these are just syntactic alternatives for features that PCRE had
520        previously implemented using the Python syntax or my own invention. The
521        other formats are all retained for compatibility.
522    
523        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
524            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
525            also .NET compatible.
526    
527        (b) A recursion or subroutine call to a named group can now be defined as
528            (?&name) as well as (?P>name).
529    
530        (c) A backreference to a named group can now be defined as \k<name> or
531            \k'name' as well as (?P=name). The new forms, as well as being in Perl
532            5.10, are also .NET compatible.
533    
534        (d) A conditional reference to a named group can now use the syntax
535            (?(<name>) or (?('name') as well as (?(name).
536    
537        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
538            groups (named and numbered) that are never evaluated inline, but can be
539            called as "subroutines" from elsewhere. In effect, the DEFINE condition
540            is always false. There may be only one alternative in such a group.
541    
542        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
543            as the simple (?(R). The condition is true only if the most recent
544            recursion is that of the given number or name. It does not search out
545            through the entire recursion stack.
546    
547        (g) The escape \gN or \g{N} has been added, where N is a positive or
548            negative number, specifying an absolute or relative reference.
549    
550    35. Tidied to get rid of some further signed/unsigned compiler warnings and
551        some "unreachable code" warnings.
552    
553    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
554        things, this adds five new scripts.
555    
556    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
557        There were also incompatibilities regarding the handling of \Q..\E inside
558        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
559        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
560    
561    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
562        matches an empty string, and forcibly breaks the loop. There were bugs in
563        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
564        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
565        separate and independent bugs (that affected different cases) have been
566        fixed.
567    
568    39. Refactored the code to abolish the use of different opcodes for small
569        capturing bracket numbers. This is a tidy that I avoided doing when I
570        removed the limit on the number of capturing brackets for 3.5 back in 2001.
571        The new approach is not only tidier, it makes it possible to reduce the
572        memory needed to fix the previous bug (38).
573    
574    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
575        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
576        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
577        mode.
578    
579    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
580        report.
581    
582    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
583        copy construction and assignment in the C++ wrapper.
584    
585    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
586        couple of bugs that could have given wrong results in the "--newline=crlf"
587        case.
588    
589    44. Added a number of casts and did some reorganization of signed/unsigned int
590        variables following suggestions from Dair Grant. Also renamed the variable
591        "this" as "item" because it is a C++ keyword.
592    
593    45. Arranged for dftables to add
594    
595          #include "pcre_internal.h"
596    
597        to pcre_chartables.c because without it, gcc 4.x may remove the array
598        definition from the final binary if PCRE is built into a static library and
599        dead code stripping is activated.
600    
601    46. For an unanchored pattern, if a match attempt fails at the start of a
602        newline sequence, and the newline setting is CRLF or ANY, and the next two
603        characters are CRLF, advance by two characters instead of one.
604    
605    
606    Version 6.7 04-Jul-06
607    ---------------------
608    
609     1. In order to handle tests when input lines are enormously long, pcretest has
610        been re-factored so that it automatically extends its buffers when
611        necessary. The code is crude, but this _is_ just a test program. The
612        default size has been increased from 32K to 50K.
613    
614     2. The code in pcre_study() was using the value of the re argument before
615        testing it for NULL. (Of course, in any sensible call of the function, it
616        won't be NULL.)
617    
618     3. The memmove() emulation function in pcre_internal.h, which is used on
619        systems that lack both memmove() and bcopy() - that is, hardly ever -
620        was missing a "static" storage class specifier.
621    
622     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
623        containing an extended class (one that cannot be represented by a bitmap
624        because it contains high-valued characters or Unicode property items, e.g.
625        [\pZ]). Almost always one would set UTF-8 mode when processing such a
626        pattern, but PCRE should not loop if you do not (it no longer does).
627        [Detail: two cases were found: (a) a repeated subpattern containing an
628        extended class; (b) a recursive reference to a subpattern that followed a
629        previous extended class. It wasn't skipping over the extended class
630        correctly when UTF-8 mode was not set.]
631    
632     5. A negated single-character class was not being recognized as fixed-length
633        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
634        compile error "lookbehind assertion is not fixed length".
635    
636     6. The RunPerlTest auxiliary script was showing an unexpected difference
637        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
638        write a Perl script that can interpret lines of an input file either as
639        byte characters or as UTF-8, which is what "perltest" was being required to
640        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
641        can't do is switch easily at run time between having the "use utf8;" pragma
642        or not. In the end, I fudged it by using the RunPerlTest script to insert
643        "use utf8;" explicitly for the UTF-8 tests.
644    
645     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
646        the end of the subject string, contrary to the documentation and to what
647        Perl does. This was true of both matching functions. Now it matches only at
648        the start of the subject and immediately after *internal* newlines.
649    
650     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
651        a pointer to an int instead of a pointer to an unsigned long int. This
652        caused problems on 64-bit systems.
653    
654     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
655        instance of the 'standard' template library not being so standard".
656    
657    10. There was no check on the number of named subpatterns nor the maximum
658        length of a subpattern name. The product of these values is used to compute
659        the size of the memory block for a compiled pattern. By supplying a very
660        long subpattern name and a large number of named subpatterns, the size
661        computation could be caused to overflow. This is now prevented by limiting
662        the length of names to 32 characters, and the number of named subpatterns
663        to 10,000.
664    
665    11. Subpatterns that are repeated with specific counts have to be replicated in
666        the compiled pattern. The size of memory for this was computed from the
667        length of the subpattern and the repeat count. The latter is limited to
668        65535, but there was no limit on the former, meaning that integer overflow
669        could in principle occur. The compiled length of a repeated subpattern is
670        now limited to 30,000 bytes in order to prevent this.
671    
672    12. Added the optional facility to have named substrings with the same name.
673    
674    13. Added the ability to use a named substring as a condition, using the
675        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
676        are numbers (not recommended). Forward references are permitted.
677    
678    14. Added forward references in named backreferences (if you see what I mean).
679    
680    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
681        pattern could run off the end of the subject. For example, the pattern
682        "(?s)(.{1,5})"8 did this with the subject "ab".
683    
684    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
685        PCRE_CASELESS was set when matching characters that were quantified with ?
686        or *.
687    
688    17. A character class other than a single negated character that had a minimum
689        but no maximum quantifier - for example [ab]{6,} - was not handled
690        correctly by pce_dfa_exec(). It would match only one character.
691    
692    18. A valid (though odd) pattern that looked like a POSIX character
693        class but used an invalid character after [ (for example [[,abc,]]) caused
694        pcre_compile() to give the error "Failed: internal error: code overflow" or
695        in some cases to crash with a glibc free() error. This could even happen if
696        the pattern terminated after [[ but there just happened to be a sequence of
697        letters, a binary zero, and a closing ] in the memory that followed.
698    
699    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
700        over the years. Originally (before any Unicode support), just the bottom 8
701        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
702        output from "man perlunicode" includes this:
703    
704          The regular expression compiler produces polymorphic opcodes.  That
705          is, the pattern adapts to the data and automatically switches to
706          the Unicode character scheme when presented with Unicode data--or
707          instead uses a traditional byte scheme when presented with byte
708          data.
709    
710        Sadly, a wide octal escape does not cause a switch, and in a string with
711        no other multibyte characters, these octal escapes are treated as before.
712        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
713        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
714        Unicode string.
715    
716        I have not perpetrated such confusion in PCRE. Up till now, it took just
717        the bottom 8 bits, as in old Perl. I have now made octal escapes with
718        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
719        translate to the appropriate multibyte character.
720    
721    29. Applied some refactoring to reduce the number of warnings from Microsoft
722        and Borland compilers. This has included removing the fudge introduced
723        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
724        a warning about an unused variable.
725    
726    21. PCRE has not included VT (character 0x0b) in the set of whitespace
727        characters since release 4.0, because Perl (from release 5.004) does not.
728        [Or at least, is documented not to: some releases seem to be in conflict
729        with the documentation.] However, when a pattern was studied with
730        pcre_study() and all its branches started with \s, PCRE still included VT
731        as a possible starting character. Of course, this did no harm; it just
732        caused an unnecessary match attempt.
733    
734    22. Removed a now-redundant internal flag bit that recorded the fact that case
735        dependency changed within the pattern. This was once needed for "required
736        byte" processing, but is no longer used. This recovers a now-scarce options
737        bit. Also moved the least significant internal flag bit to the most-
738        significant bit of the word, which was not previously used (hangover from
739        the days when it was an int rather than a uint) to free up another bit for
740        the future.
741    
742    23. Added support for CRLF line endings as well as CR and LF. As well as the
743        default being selectable at build time, it can now be changed at runtime
744        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
745        specify that it is scanning data with non-default line endings.
746    
747    24. Changed the definition of CXXLINK to make it agree with the definition of
748        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
749    
750    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
751        recursions. This makes a big different to stack usage for some patterns.
752    
753    26. If a subpattern containing a named recursion or subroutine reference such
754        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
755        the space required for the compiled pattern went wrong and gave too small a
756        value. Depending on the environment, this could lead to "Failed: internal
757        error: code overflow at offset 49" or "glibc detected double free or
758        corruption" errors.
759    
760    27. Applied patches from Google (a) to support the new newline modes and (b) to
761        advance over multibyte UTF-8 characters in GlobalReplace.
762    
763    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
764        difference for some implementation of PCRE in some Windows version.
765    
766    29. Added some extra testing facilities to pcretest:
767    
768        \q<number>   in a data line sets the "match limit" value
769        \Q<number>   in a data line sets the "match recursion limt" value
770        -S <number>  sets the stack size, where <number> is in megabytes
771    
772        The -S option isn't available for Windows.
773    
774    
775    Version 6.6 06-Feb-06
776    ---------------------
777    
778     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
779        in pcreposix.h. I have copied the definition from pcre.h.
780    
781     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
782        because pcre.h is no longer a built file.
783    
784     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
785        not normally included in the compiled code.
786    
787    
788    Version 6.5 01-Feb-06
789    ---------------------
790    
791     1. When using the partial match feature with pcre_dfa_exec(), it was not
792        anchoring the second and subsequent partial matches at the new starting
793        point. This could lead to incorrect results. For example, with the pattern
794        /1234/, partially matching against "123" and then "a4" gave a match.
795    
796     2. Changes to pcregrep:
797    
798        (a) All non-match returns from pcre_exec() were being treated as failures
799            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
800            error message is output. Some extra information is given for the
801            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
802            probably the only errors that are likely to be caused by users (by
803            specifying a regex that has nested indefinite repeats, for instance).
804            If there are more than 20 of these errors, pcregrep is abandoned.
805    
806        (b) A binary zero was treated as data while matching, but terminated the
807            output line if it was written out. This has been fixed: binary zeroes
808            are now no different to any other data bytes.
809    
810        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
811            used to set a locale for matching. The --locale=xxxx long option has
812            been added (no short equivalent) to specify a locale explicitly on the
813            pcregrep command, overriding the environment variables.
814    
815        (d) When -B was used with -n, some line numbers in the output were one less
816            than they should have been.
817    
818        (e) Added the -o (--only-matching) option.
819    
820        (f) If -A or -C was used with -c (count only), some lines of context were
821            accidentally printed for the final match.
822    
823        (g) Added the -H (--with-filename) option.
824    
825        (h) The combination of options -rh failed to suppress file names for files
826            that were found from directory arguments.
827    
828        (i) Added the -D (--devices) and -d (--directories) options.
829    
830        (j) Added the -F (--fixed-strings) option.
831    
832        (k) Allow "-" to be used as a file name for -f as well as for a data file.
833    
834        (l) Added the --colo(u)r option.
835    
836        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
837            is not present by default.
838    
839     3. A nasty bug was discovered in the handling of recursive patterns, that is,
840        items such as (?R) or (?1), when the recursion could match a number of
841        alternatives. If it matched one of the alternatives, but subsequently,
842        outside the recursion, there was a failure, the code tried to back up into
843        the recursion. However, because of the way PCRE is implemented, this is not
844        possible, and the result was an incorrect result from the match.
845    
846        In order to prevent this happening, the specification of recursion has
847        been changed so that all such subpatterns are automatically treated as
848        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
849    
850     4. I had overlooked the fact that, in some locales, there are characters for
851        which isalpha() is true but neither isupper() nor islower() are true. In
852        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
853        and ordfeminine) are like this. This affected the treatment of \w and \W
854        when they appeared in character classes, but not when they appeared outside
855        a character class. The bit map for "word" characters is now created
856        separately from the results of isalnum() instead of just taking it from the
857        upper, lower, and digit maps. (Plus the underscore character, of course.)
858    
859     5. The above bug also affected the handling of POSIX character classes such as
860        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
861        permanent tables. Instead, the bit maps for such a class were previously
862        created as the appropriate unions of the upper, lower, and digit bitmaps.
863        Now they are created by subtraction from the [[:word:]] class, which has
864        its own bitmap.
865    
866     6. The [[:blank:]] character class matches horizontal, but not vertical space.
867        It is created by subtracting the vertical space characters (\x09, \x0a,
868        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
869        subtraction was done in the overall bitmap for a character class, meaning
870        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
871        be recognized. This bug has been fixed.
872    
873     7. Patches from the folks at Google:
874    
875          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
876          real life, but is still worth protecting against".
877    
878          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
879          regular expressions".
880    
881          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
882          have it.
883    
884          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
885          "configure" and the latter not, in order to fix a problem somebody had
886          with compiling the Arg class on HP-UX.
887    
888          (e) Improve the error-handling of the C++ wrapper a little bit.
889    
890          (f) New tests for checking recursion limiting.
891    
892     8. The pcre_memmove() function, which is used only if the environment does not
893        have a standard memmove() function (and is therefore rarely compiled),
894        contained two bugs: (a) use of int instead of size_t, and (b) it was not
895        returning a result (though PCRE never actually uses the result).
896    
897     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
898        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
899        returned instead of calling malloc() with an overflowing number that would
900        most likely cause subsequent chaos.
901    
902    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
903    
904    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
905        with this option is matched, the nmatch and pmatch options of regexec() are
906        ignored.
907    
908    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
909        provided in case anyone wants to the the POSIX interface with UTF-8
910        strings.
911    
912    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
913        C++ linking (needed for some HP-UX environments).
914    
915    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
916        (unused parameter) and in the pcre_printint() function (omitted "default"
917        switch label when the default is to do nothing).
918    
919    15. Added some code to make it possible, when PCRE is compiled as a C++
920        library, to replace subject pointers for pcre_exec() with a smart pointer
921        class, thus making it possible to process discontinuous strings.
922    
923    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
924        much the same function. They were added by different people who were trying
925        to make PCRE easy to compile on non-Unix systems. It has been suggested
926        that PCRE_EXPORT be abolished now that there is more automatic apparatus
927        for compiling on Windows systems. I have therefore replaced it with
928        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
929        defaults to "extern" for C or "extern C" for C++, which works fine on
930        Unix-like systems. It is now possible to override the value of PCRE_DATA_
931        SCOPE with something explicit in config.h. In addition:
932    
933        (a) pcreposix.h still had just "extern" instead of either of these macros;
934            I have replaced it with PCRE_DATA_SCOPE.
935    
936        (b) Functions such as _pcre_xclass(), which are internal to the library,
937            but external in the C sense, all had PCRE_EXPORT in their definitions.
938            This is apparently wrong for the Windows case, so I have removed it.
939            (It makes no difference on Unix-like systems.)
940    
941    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
942        of recursive calls to match(). This is different to MATCH_LIMIT because
943        that limits the total number of calls to match(), not all of which increase
944        the depth of recursion. Limiting the recursion depth limits the amount of
945        stack (or heap if NO_RECURSE is set) that is used. The default can be set
946        when PCRE is compiled, and changed at run time. A patch from Google adds
947        this functionality to the C++ interface.
948    
949    18. Changes to the handling of Unicode character properties:
950    
951        (a) Updated the table to Unicode 4.1.0.
952    
953        (b) Recognize characters that are not in the table as "Cn" (undefined).
954    
955        (c) I revised the way the table is implemented to a much improved format
956            which includes recognition of ranges. It now supports the ranges that
957            are defined in UnicodeData.txt, and it also amalgamates other
958            characters into ranges. This has reduced the number of entries in the
959            table from around 16,000 to around 3,000, thus reducing its size
960            considerably. I realized I did not need to use a tree structure after
961            all - a binary chop search is just as efficient. Having reduced the
962            number of entries, I extended their size from 6 bytes to 8 bytes to
963            allow for more data.
964    
965        (d) Added support for Unicode script names via properties such as \p{Han}.
966    
967    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
968        matching that character.
969    
970    20. When matching a repeated Unicode property with a minimum greater than zero,
971        (for example \pL{2,}), PCRE could look past the end of the subject if it
972        reached it while seeking the minimum number of characters. This could
973        happen only if some of the characters were more than one byte long, because
974        there is a check for at least the minimum number of bytes.
975    
976    21. Refactored the implementation of \p and \P so as to be more general, to
977        allow for more different types of property in future. This has changed the
978        compiled form incompatibly. Anybody with saved compiled patterns that use
979        \p or \P will have to recompile them.
980    
981    22. Added "Any" and "L&" to the supported property types.
982    
983    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
984        but give a compile time error if the value is greater than 0xff.
985    
986    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
987        accidentally not being installed or uninstalled.
988    
989    25. The pcre.h file was built from pcre.h.in, but the only changes that were
990        made were to insert the current release number. This seemed silly, because
991        it made things harder for people building PCRE on systems that don't run
992        "configure". I have turned pcre.h into a distributed file, no longer built
993        by "configure", with the version identification directly included. There is
994        no longer a pcre.h.in file.
995    
996        However, this change necessitated a change to the pcre-config script as
997        well. It is built from pcre-config.in, and one of the substitutions was the
998        release number. I have updated configure.ac so that ./configure now finds
999        the release number by grepping pcre.h.
1000    
1001    26. Added the ability to run the tests under valgrind.
1002    
1003    
1004    Version 6.4 05-Sep-05
1005    ---------------------
1006    
1007     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1008        "--" to be printed when multiple files were scanned, even when none of the
1009        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1010        consider it to be a bug, and have restored the previous behaviour.
1011    
1012     2. A couple of code tidies to get rid of compiler warnings.
1013    
1014     3. The pcretest program used to cheat by referring to symbols in the library
1015        whose names begin with _pcre_. These are internal symbols that are not
1016        really supposed to be visible externally, and in some environments it is
1017        possible to suppress them. The cheating is now confined to including
1018        certain files from the library's source, which is a bit cleaner.
1019    
1020     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1021        file's purpose clearer.
1022    
1023     5. Reorganized pcre_ucp_findchar().
1024    
1025    
1026    Version 6.3 15-Aug-05
1027    ---------------------
1028    
1029     1. The file libpcre.pc.in did not have general read permission in the tarball.
1030    
1031     2. There were some problems when building without C++ support:
1032    
1033        (a) If C++ support was not built, "make install" and "make test" still
1034            tried to test it.
1035    
1036        (b) There were problems when the value of CXX was explicitly set. Some
1037            changes have been made to try to fix these, and ...
1038    
1039        (c) --disable-cpp can now be used to explicitly disable C++ support.
1040    
1041        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1042            backslash in a target when C++ was disabled. This confuses some
1043            versions of "make", apparently. Using an intermediate variable solves
1044            this. (Same for CPP_LOBJ.)
1045    
1046     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1047        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1048        necessary on certain architectures.
1049    
1050     4. Added a setting of -export-symbols-regex to the link command to remove
1051        those symbols that are exported in the C sense, but actually are local
1052        within the library, and not documented. Their names all begin with
1053        "_pcre_". This is not a perfect job, because (a) we have to except some
1054        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1055        available (and never for static libraries). I have made a note to try to
1056        find a way round (a) in the future.
1057    
1058    
1059    Version 6.2 01-Aug-05
1060    ---------------------
1061    
1062     1. There was no test for integer overflow of quantifier values. A construction
1063        such as {1111111111111111} would give undefined results. What is worse, if
1064        a minimum quantifier for a parenthesized subpattern overflowed and became
1065        negative, the calculation of the memory size went wrong. This could have
1066        led to memory overwriting.
1067    
1068     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1069    
1070     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1071        operating environments where this matters.
1072    
1073     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1074        PCRE options from within the C++ wrapper.
1075    
1076     5. Named capturing subpatterns were not being correctly counted when a pattern
1077        was compiled. This caused two problems: (a) If there were more than 100
1078        such subpatterns, the calculation of the memory needed for the whole
1079        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1080        back references of the form \12, where the number was greater than 9, were
1081        not recognized as back references, even though there were sufficient
1082        previous subpatterns.
1083    
1084     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1085        versions of gcc, e.g. 2.95.4.
1086    
1087    
1088    Version 6.1 21-Jun-05
1089    ---------------------
1090    
1091     1. There was one reference to the variable "posix" in pcretest.c that was not
1092        surrounded by "#if !defined NOPOSIX".
1093    
1094     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1095        the cross-check on the old pcre_info() function, for the benefit of the
1096        cut-down version of PCRE that is currently imported into Exim.
1097    
1098     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1099        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1100        patterns that start (?i) but I don't think that matters. The use of (?i) is
1101        just an example; this all applies to the other options as well.
1102    
1103     4. Since libtool seems to echo the compile commands it is issuing, the output
1104        from "make" can be reduced a bit by putting "@" in front of each libtool
1105        compile command.
1106    
1107     5. Patch from the folks at Google for configure.in to be a bit more thorough
1108        in checking for a suitable C++ installation before trying to compile the
1109        C++ stuff. This should fix a reported problem when a compiler was present,
1110        but no suitable headers.
1111    
1112     6. The man pages all had just "PCRE" as their title. I have changed them to
1113        be the relevant file name. I have also arranged that these names are
1114        retained in the file doc/pcre.txt, which is a concatenation in text format
1115        of all the man pages except the little individual ones for each function.
1116    
1117     7. The NON-UNIX-USE file had not been updated for the different set of source
1118        files that come with release 6. I also added a few comments about the C++
1119        wrapper.
1120    
1121    
1122    Version 6.0 07-Jun-05
1123    ---------------------
1124    
1125     1. Some minor internal re-organization to help with my DFA experiments.
1126    
1127     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1128        didn't matter for the library itself when fully configured, but did matter
1129        when compiling without UCP support, or within Exim, where the ucp files are
1130        not imported.
1131    
1132     3. Refactoring of the library code to split up the various functions into
1133        different source modules. The addition of the new DFA matching code (see
1134        below) to a single monolithic source would have made it really too
1135        unwieldy, quite apart from causing all the code to be include in a
1136        statically linked application, when only some functions are used. This is
1137        relevant even without the DFA addition now that patterns can be compiled in
1138        one application and matched in another.
1139    
1140        The downside of splitting up is that there have to be some external
1141        functions and data tables that are used internally in different modules of
1142        the library but which are not part of the API. These have all had their
1143        names changed to start with "_pcre_" so that they are unlikely to clash
1144        with other external names.
1145    
1146     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1147        a different (DFA) algorithm. Although it is slower than the original
1148        function, it does have some advantages for certain types of matching
1149        problem.
1150    
1151     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1152        including restarting after a partial match.
1153    
1154     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1155        defined when compiling for Windows was sent to me. I have put it into the
1156        code, though I have no means of testing or verifying it.
1157    
1158     7. Added the pcre_refcount() auxiliary function.
1159    
1160     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1161        match before or at the first newline in the subject string. In pcretest,
1162        the /f option on a pattern can be used to set this.
1163    
1164     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1165        would behave wrongly. This has been present in PCRE since release 4.0.
1166    
1167    10. A number of changes to the pcregrep command:
1168    
1169        (a) Refactored how -x works; insert ^(...)$ instead of setting
1170            PCRE_ANCHORED and checking the length, in preparation for adding
1171            something similar for -w.
1172    
1173        (b) Added the -w (match as a word) option.
1174    
1175        (c) Refactored the way lines are read and buffered so as to have more
1176            than one at a time available.
1177    
1178        (d) Implemented a pcregrep test script.
1179    
1180        (e) Added the -M (multiline match) option. This allows patterns to match
1181            over several lines of the subject. The buffering ensures that at least
1182            8K, or the rest of the document (whichever is the shorter) is available
1183            for matching (and similarly the previous 8K for lookbehind assertions).
1184    
1185        (f) Changed the --help output so that it now says
1186    
1187              -w, --word-regex(p)
1188    
1189            instead of two lines, one with "regex" and the other with "regexp"
1190            because that confused at least one person since the short forms are the
1191            same. (This required a bit of code, as the output is generated
1192            automatically from a table. It wasn't just a text change.)
1193    
1194        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1195            option but starts with a hyphen. Could be a pattern or a path name
1196            starting with a hyphen, for instance.
1197    
1198        (h) "-" can be given as a file name to represent stdin.
1199    
1200        (i) When file names are being printed, "(standard input)" is used for
1201            the standard input, for compatibility with GNU grep. Previously
1202            "<stdin>" was used.
1203    
1204        (j) The option --label=xxx can be used to supply a name to be used for
1205            stdin when file names are being printed. There is no short form.
1206    
1207        (k) Re-factored the options decoding logic because we are going to add
1208            two more options that take data. Such options can now be given in four
1209            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1210    
1211        (l) Added the -A, -B, and -C options for requesting that lines of context
1212            around matches be printed.
1213    
1214        (m) Added the -L option to print the names of files that do not contain
1215            any matching lines, that is, the complement of -l.
1216    
1217        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1218            continue to scan other files.
1219    
1220        (o) The -s option was incorrectly implemented. For compatibility with other
1221            greps, it now suppresses the error message for a non-existent or non-
1222            accessible file (but not the return code). There is a new option called
1223            -q that suppresses the output of matching lines, which was what -s was
1224            previously doing.
1225    
1226        (p) Added --include and --exclude options to specify files for inclusion
1227            and exclusion when recursing.
1228    
1229    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1230        Hopefully, it now does.
1231    
1232    12. Missing cast in pcre_study().
1233    
1234    13. Added an "uninstall" target to the makefile.
1235    
1236    14. Replaced "extern" in the function prototypes in Makefile.in with
1237        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1238        world, but is set differently for Windows.
1239    
1240    15. Added a second compiling function called pcre_compile2(). The only
1241        difference is that it has an extra argument, which is a pointer to an
1242        integer error code. When there is a compile-time failure, this is set
1243        non-zero, in addition to the error test pointer being set to point to an
1244        error message. The new argument may be NULL if no error number is required
1245        (but then you may as well call pcre_compile(), which is now just a
1246        wrapper). This facility is provided because some applications need a
1247        numeric error indication, but it has also enabled me to tidy up the way
1248        compile-time errors are handled in the POSIX wrapper.
1249    
1250    16. Added VPATH=.libs to the makefile; this should help when building with one
1251        prefix path and installing with another. (Or so I'm told by someone who
1252        knows more about this stuff than I do.)
1253    
1254    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1255        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1256        match everything, including newlines. This is not POSIX-compatible, but
1257        somebody wanted the feature. From pcretest it can be activated by using
1258        both the P and the s flags.
1259    
1260    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1261    
1262    19. libpcre.pc was being incorrectly installed as executable.
1263    
1264    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1265        it now also looks for '\r' so that it will work unmodified on Windows.
1266    
1267    21. Added Google's contributed C++ wrapper to the distribution.
1268    
1269    22. Added some untidy missing memory free() calls in pcretest, to keep
1270        Electric Fence happy when testing.
1271    
1272    
1273    
1274    Version 5.0 13-Sep-04
1275    ---------------------
1276    
1277     1. Internal change: literal characters are no longer packed up into items
1278        containing multiple characters in a single byte-string. Each character
1279        is now matched using a separate opcode. However, there may be more than one
1280        byte in the character in UTF-8 mode.
1281    
1282     2. The pcre_callout_block structure has two new fields: pattern_position and
1283        next_item_length. These contain the offset in the pattern to the next match
1284        item, and its length, respectively.
1285    
1286     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1287        insertion of callouts before each pattern item. Added the /C option to
1288        pcretest to make use of this.
1289    
1290     4. On the advice of a Windows user, the lines
1291    
1292          #if defined(_WIN32) || defined(WIN32)
1293          _setmode( _fileno( stdout ), 0x8000 );
1294          #endif  /* defined(_WIN32) || defined(WIN32) */
1295    
1296        have been added to the source of pcretest. This apparently does useful
1297        magic in relation to line terminators.
1298    
1299     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1300        for the benefit of those environments where the "b" makes a difference.
1301    
1302     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1303        to know about it. I have put a hack into configure.in that adds in code
1304        to set GCC=yes if CC=icc. This seems to end up at a point in the
1305        generated configure script that is early enough to affect the setting of
1306        compiler options, which is what is needed, but I have no means of testing
1307        whether it really works. (The user who reported this had patched the
1308        generated configure script, which of course I cannot do.)
1309    
1310        LATER: After change 22 below (new libtool files), the configure script
1311        seems to know about icc (and also ecc). Therefore, I have commented out
1312        this hack in configure.in.
1313    
1314     7. Added support for pkg-config (2 patches were sent in).
1315    
1316     8. Negated POSIX character classes that used a combination of internal tables
1317        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1318        [[:^ascii]]. Typically, they would match almost any characters. The other
1319        POSIX classes were not broken in this way.
1320    
1321     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1322        to find the match, as PCRE was deluded into thinking that the match had to
1323        start at the start point or following a newline. The same bug applied to
1324        patterns with negative forward assertions or any backward assertions
1325        preceding ".*" at the start, unless the pattern required a fixed first
1326        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1327    
1328    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1329        starting at the last subject character, bytes beyond the end of the subject
1330        string were read.
1331    
1332    11. Renamed the variable "class" as "classbits" to make life easier for C++
1333        users. (Previously there was a macro definition, but it apparently wasn't
1334        enough.)
1335    
1336    12. Added the new field "tables" to the extra data so that tables can be passed
1337        in at exec time, or the internal tables can be re-selected. This allows
1338        a compiled regex to be saved and re-used at a later time by a different
1339        program that might have everything at different addresses.
1340    
1341    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1342        -R library as well as a -L library.
1343    
1344    14. The debugging options of pcretest (-d on the command line or D on a
1345        pattern) showed incorrect output for anything following an extended class
1346        that contained multibyte characters and which was followed by a quantifier.
1347    
1348    15. Added optional support for general category Unicode character properties
1349        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1350        support. It adds about 90K to the size of the library. The meanings of the
1351        inbuilt class escapes such as \d and \s have NOT been changed.
1352    
1353    16. Updated pcredemo.c to include calls to free() to release the memory for the
1354        compiled pattern.
1355    
1356    17. The generated file chartables.c was being created in the source directory
1357        instead of in the building directory. This caused the build to fail if the
1358        source directory was different from the building directory, and was
1359        read-only.
1360    
1361    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1362        file. No doubt somebody will tell me if they don't make sense... Also added
1363        Dan Mooney's comments about building on OpenVMS.
1364    
1365    19. Added support for partial matching via the PCRE_PARTIAL option for
1366        pcre_exec() and the \P data escape in pcretest.
1367    
1368    20. Extended pcretest with 3 new pattern features:
1369    
1370        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1371              write the compiled pattern to the file whose name is "rest-of-line".
1372              This is a straight binary dump of the data, with the saved pointer to
1373              the character tables forced to be NULL. The study data, if any, is
1374              written too. After writing, pcretest reads a new pattern.
1375    
1376        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1377              compiled pattern from the given file. There must not be any
1378              occurrences of "<" in the file name (pretty unlikely); if there are,
1379              pcretest will instead treat the initial "<" as a pattern delimiter.
1380              After reading in the pattern, pcretest goes on to read data lines as
1381              usual.
1382    
1383        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1384              and 16-bit fields in a compiled pattern, to simulate a pattern that
1385              was compiled on a host of opposite endianness.
1386    
1387    21. The pcre-exec() function can now cope with patterns that were compiled on
1388        hosts of opposite endianness, with this restriction:
1389    
1390          As for any compiled expression that is saved and used later, the tables
1391          pointer field cannot be preserved; the extra_data field in the arguments
1392          to pcre_exec() should be used to pass in a tables address if a value
1393          other than the default internal tables were used at compile time.
1394    
1395    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1396        now diagnosed as an error. Previously, most of the time, a negative number
1397        would have been treated as zero, but if in addition "ovector" was passed as
1398        NULL, a crash could occur.
1399    
1400    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1401        new versions from the libtool 1.5 distribution (the last one is a copy of
1402        a file called libtool.m4). This seems to have fixed the need to patch
1403        "configure" to support Darwin 1.3 (which I used to do). However, I still
1404        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1405        workstation).
1406    
1407    24. Changed the PCRE licence to be the more standard "BSD" licence.
1408    
1409    
1410    Version 4.5 01-Dec-03
1411    ---------------------
1412    
1413     1. There has been some re-arrangement of the code for the match() function so
1414        that it can be compiled in a version that does not call itself recursively.
1415        Instead, it keeps those local variables that need separate instances for
1416        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1417        needs to "recurse". Keeping track of where control must go is done by means
1418        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1419        hide most of the details from the main code, and operates only if
1420        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1421        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1422        operating.
1423    
1424        To make it easier for callers to provide specially tailored get/free
1425        functions for this usage, two new functions, pcre_stack_malloc, and
1426        pcre_stack_free, are used. They are always called in strict stacking order,
1427        and the size of block requested is always the same.
1428    
1429        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1430        PCRE has been compiled to use the stack or the heap for recursion. The
1431        -C option of pcretest uses this to show which version is compiled.
1432    
1433        A new data escape \S, is added to pcretest; it causes the amounts of store
1434        obtained and freed by both kinds of malloc/free at match time to be added
1435        to the output.
1436    
1437     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1438        what's available on my current Linux desktop machine.
1439    
1440     3. When matching a UTF-8 string, the test for a valid string at the start has
1441        been extended. If start_offset is not zero, PCRE now checks that it points
1442        to a byte that is the start of a UTF-8 character. If not, it returns
1443        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1444        this is necessary because there may be backward assertions in the pattern.
1445        When matching the same subject several times, it may save resources to use
1446        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1447    
1448     4. The code for checking the validity of UTF-8 strings has been tightened so
1449        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1450        containing "overlong sequences".
1451    
1452     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1453        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1454        should have been "&", but it just so happened that all the cases this let
1455        through by mistake were picked up later in the function.
1456    
1457     6. I had used a variable called "isblank" - this is a C99 function, causing
1458        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1459    
1460     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1461        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1462        so the version is shown; (c) stop "make test" echoing "./RunTest".
1463    
1464     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1465    
1466     9. The prototype for memmove() for systems that don't have it was using
1467        size_t, but the inclusion of the header that defines size_t was later. I've
1468        moved the #includes for the C headers earlier to avoid this.
1469    
1470    10. Added some adjustments to the code to make it easier to compiler on certain
1471        special systems:
1472    
1473          (a) Some "const" qualifiers were missing.
1474          (b) Added the macro EXPORT before all exported functions; by default this
1475              is defined to be empty.
1476          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1477              that it reads its output file name as an argument instead of writing
1478              to the standard output and assuming this can be redirected.
1479    
1480    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1481        class containing characters with values greater than 255, PCRE compilation
1482        went into a loop.
1483    
1484    12. A recursive reference to a subpattern that was within another subpattern
1485        that had a minimum quantifier of zero caused PCRE to crash. For example,
1486        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1487        recursion. If the recursively-called subpattern itself had a zero repeat,
1488        that was OK.
1489    
1490    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1491        buffer into which it was copied (for escape processing) was still set at
1492        1024, so long lines caused crashes.
1493    
1494    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1495        "internal error: code overflow...". This applied to any character class
1496        that was followed by a possessive quantifier.
1497    
1498    15. Modified the Makefile to add libpcre.la as a prerequisite for
1499        libpcreposix.la because I was told this is needed for a parallel build to
1500        work.
1501    
1502    16. If a pattern that contained .* following optional items at the start was
1503        studied, the wrong optimizing data was generated, leading to matching
1504        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1505        matching string must start with a or b or c. The correct conclusion for
1506        this pattern is that a match can start with any character.
1507    
1508    
1509    Version 4.4 13-Aug-03
1510    ---------------------
1511    
1512     1. In UTF-8 mode, a character class containing characters with values between
1513        127 and 255 was not handled correctly if the compiled pattern was studied.
1514        In fixing this, I have also improved the studying algorithm for such
1515        classes (slightly).
1516    
1517     2. Three internal functions had redundant arguments passed to them. Removal
1518        might give a very teeny performance improvement.
1519    
1520     3. Documentation bug: the value of the capture_top field in a callout is *one
1521        more than* the number of the hightest numbered captured substring.
1522    
1523     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1524        in incorrectly linking with a previously installed version. They now link
1525        explicitly with libpcre.la.
1526    
1527     5. configure.in no longer needs to recognize Cygwin specially.
1528    
1529     6. A problem in pcre.in for Windows platforms is fixed.
1530    
1531     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1532        pcretest, it used to include the size of the study block as part of its
1533        output. Unfortunately, the structure contains a field that has a different
1534        size on different hardware architectures. This meant that the tests that
1535        showed this size failed. As the block is currently always of a fixed size,
1536        this information isn't actually particularly useful in pcretest output, so
1537        I have just removed it.
1538    
1539     8. Three pre-processor statements accidentally did not start in column 1.
1540        Sadly, there are *still* compilers around that complain, even though
1541        standard C has not required this for well over a decade. Sigh.
1542    
1543     9. In pcretest, the code for checking callouts passed small integers in the
1544        callout_data field, which is a void * field. However, some picky compilers
1545        complained about the casts involved for this on 64-bit systems. Now
1546        pcretest passes the address of the small integer instead, which should get
1547        rid of the warnings.
1548    
1549    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1550        both compile and run time, and gives an error if an invalid UTF-8 sequence
1551        is found. There is a option for disabling this check in cases where the
1552        string is known to be correct and/or the maximum performance is wanted.
1553    
1554    11. In response to a bug report, I changed one line in Makefile.in from
1555    
1556            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1557        to
1558            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1559    
1560        to look similar to other lines, but I have no way of telling whether this
1561        is the right thing to do, as I do not use Windows. No doubt I'll get told
1562        if it's wrong...
1563    
1564    
1565    Version 4.3 21-May-03
1566    ---------------------
1567    
1568    1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1569       Makefile.
1570    
1571    2. Some refactoring to improve the quality of the code:
1572    
1573       (i)   The utf8_table... variables are now declared "const".
1574    
1575       (ii)  The code for \cx, which used the "case flipping" table to upper case
1576             lower case letters, now just substracts 32. This is ASCII-specific,
1577             but the whole concept of \cx is ASCII-specific, so it seems
1578             reasonable.
1579    
1580       (iii) PCRE was using its character types table to recognize decimal and
1581             hexadecimal digits in the pattern. This is silly, because it handles
1582             only 0-9, a-f, and A-F, but the character types table is locale-
1583             specific, which means strange things might happen. A private
1584             table is now used for this - though it costs 256 bytes, a table is
1585             much faster than multiple explicit tests. Of course, the standard
1586             character types table is still used for matching digits in subject
1587             strings against \d.
1588    
1589       (iv)  Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1590             ending in _t are). So I've renamed it as ESC_tee.
1591    
1592    3. The first argument for regexec() in the POSIX wrapper should have been
1593       defined as "const".
1594    
1595    4. Changed pcretest to use malloc() for its buffers so that they can be
1596       Electric Fenced for debugging.
1597    
1598    5. There were several places in the code where, in UTF-8 mode, PCRE would try
1599       to read one or more bytes before the start of the subject string. Often this
1600       had no effect on PCRE's behaviour, but in some circumstances it could
1601       provoke a segmentation fault.
1602    
1603    6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1604       to try to read one or more bytes before the start of the subject string.
1605    
1606    7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1607       UTF-8 support could misbehave in various ways if the subject string
1608       contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1609       area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1610       back over UTF-8 characters.)
1611    
1612    
1613    Version 4.2 14-Apr-03
1614    ---------------------
1615    
1616    1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1617    
1618    2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1619         [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1620         [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1621         [WIN_PREFIX]: new variable, "cyg" for Cygwin
1622         * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1623           and BUILD_EXEEXT
1624         Note: automatic setting of the BUILD variables is not yet working
1625         set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1626           compile-time but not at link-time
1627         [LINK]: use for linking executables only
1628         make different versions for Windows and non-Windows
1629         [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1630           libraries
1631         [LINK_FOR_BUILD]: new variable
1632         [OBJEXT]: use throughout
1633         [EXEEXT]: use throughout
1634         <winshared>: new target
1635         <wininstall>: new target
1636         <dftables.o>: use native compiler
1637         <dftables>: use native linker
1638         <install>: handle Windows platform correctly
1639         <clean>: ditto
1640         <check>: ditto
1641         copy DLL to top builddir before testing
1642    
1643       As part of these changes, -no-undefined was removed again. This was reported
1644       to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1645       in any case.
1646    
1647    3. Some tidies to get rid of compiler warnings:
1648    
1649       . In the match_data structure, match_limit was an unsigned long int, whereas
1650         match_call_count was an int. I've made them both unsigned long ints.
1651    
1652       . In pcretest the fact that a const uschar * doesn't automatically cast to
1653         a void * provoked a warning.
1654    
1655       . Turning on some more compiler warnings threw up some "shadow" variables
1656         and a few more missing casts.
1657    
1658    4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1659       option, a class that contained a single character with a value between 128
1660       and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1661    
1662    5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1663       option, a class that contained several characters, but with at least one
1664       whose value was between 128 and 255 caused PCRE to crash.
1665    
1666    
1667    Version 4.1 12-Mar-03
1668    ---------------------
1669    
1670    1. Compiling with gcc -pedantic found a couple of places where casts were
1671    needed, and a string in dftables.c that was longer than standard compilers are
1672    required to support.
1673    
1674    2. Compiling with Sun's compiler found a few more places where the code could
1675    be tidied up in order to avoid warnings.
1676    
1677    3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1678    first of these names is deprecated in the latest Autoconf in favour of the name
1679    CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1680    compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1681    analogy I have changed it to CFLAGS_FOR_BUILD.
1682    
1683    4. Added -no-undefined to the linking command in the Makefile, because this is
1684    apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1685    linking step for the pcreposix library.
1686    
1687    5. PCRE was failing to diagnose the case of two named groups with the same
1688    name.
1689    
1690    6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1691    literal character that is needed in the subject for a match, and scans along to
1692    ensure that it is present before embarking on the full matching process. This
1693    saves time in cases of nested unlimited repeats that are never going to match.
1694    Problem: the scan can take a lot of time if the subject is very long (e.g.
1695    megabytes), thus penalizing straightforward matches. It is now done only if the
1696    amount of subject to be scanned is less than 1000 bytes.
1697    
1698    7. A lesser problem with the same optimization is that it was recording the
1699    first character of an anchored pattern as "needed", thus provoking a search
1700    right along the subject, even when the first match of the pattern was going to
1701    fail. The "needed" character is now not set for anchored patterns, unless it
1702    follows something in the pattern that is of non-fixed length. Thus, it still
1703    fulfils its original purpose of finding quick non-matches in cases of nested
1704    unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1705    
1706    
1707    Version 4.0 17-Feb-03
1708    ---------------------
1709    
1710    1. If a comment in an extended regex that started immediately after a meta-item
1711    extended to the end of string, PCRE compiled incorrect data. This could lead to
1712    all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1713    
1714    2. Moved to autoconf 2.53 and libtool 1.4.2.
1715    
1716    3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1717    the special perltest8 script is no longer needed - all the tests can be run
1718    from a single perltest script.
1719    
1720    4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1721    by \s. It has now been removed in PCRE. This means it isn't recognized as
1722    whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1723    class [:space:] *does* include VT, thereby creating a mess.
1724    
1725    5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1726    space and tab.
1727    
1728    6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1729    its new features into the main test script, reducing the number of scripts.
1730    
1731    7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1732    were backward compatible, and made the (?i) apply to the whole pattern, as if
1733    /i were given. Now it behaves more logically, and applies the option setting
1734    only to what follows. PCRE has been changed to follow suit. However, if it
1735    finds options settings right at the start of the pattern, it extracts them into
1736    the global options, as before. Thus, they show up in the info data.
1737    
1738    8. Added support for the \Q...\E escape sequence. Characters in between are
1739    treated as literals. This is slightly different from Perl in that $ and @ are
1740    also handled as literals inside the quotes. In Perl, they will cause variable
1741    interpolation. Note the following examples:
1742    
1743        Pattern            PCRE matches      Perl matches
1744    
1745        \Qabc$xyz\E        abc$xyz           abc followed by the contents of $xyz
1746        \Qabc\$xyz\E       abc\$xyz          abc\$xyz
1747        \Qabc\E\$\Qxyz\E   abc$xyz           abc$xyz
1748    
1749    For compatibility with Perl, \Q...\E sequences are recognized inside character
1750    classes as well as outside them.
1751    
1752    9. Re-organized 3 code statements in pcretest to avoid "overflow in
1753    floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1754    (size_t) cast to one statement in pcretest and one in pcreposix to avoid
1755    signed/unsigned warnings.
1756    
1757    10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
1758    option for pcretest, so I've replaced it by a simple function that does just
1759    that job.
1760    
1761    11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
1762    "pcregrep -".
1763    
1764    12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
1765    Java package. This provides some syntactic sugar for simple cases of what my
1766    documentation calls "once-only subpatterns". A pattern such as x*+ is the same
1767    as (?>x*). In other words, if what is inside (?>...) is just a single repeated
1768    item, you can use this simplified notation. Note that only makes sense with
1769    greedy quantifiers. Consequently, the use of the possessive quantifier forces
1770    greediness, whatever the setting of the PCRE_UNGREEDY option.
1771    
1772    13. A change of greediness default within a pattern was not taking effect at
1773    the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
1774    subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
1775    was abstracted outside.
1776    
1777    14. PCRE now supports the \G assertion. It is true when the current matching
1778    position is at the start point of the match. This differs from \A when the
1779    starting offset is non-zero. Used with the /g option of pcretest (or similar
1780    code), it works in the same way as it does for Perl's /g option. If all
1781    alternatives of a regex begin with \G, the expression is anchored to the start
1782    match position, and the "anchored" flag is set in the compiled expression.
1783    
1784    15. Some bugs concerning the handling of certain option changes within patterns
1785    have been fixed. These applied to options other than (?ims). For example,
1786    "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
1787    been the other way round. Some of this was related to change 7 above.
1788    
1789    16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
1790    features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
1791    and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
1792    POSIX classes only within a class (e.g. /[[:alpha:]]/).
1793    
1794    17. Added support for Perl's \C escape. This matches one byte, even in UTF8
1795    mode. Unlike ".", it always matches newline, whatever the setting of
1796    PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
1797    assertions. Perl allows it, but it doesn't (in general) work because it can't
1798    calculate the length of the lookbehind. At least, that's the case for Perl
1799    5.8.0 - I've been told they are going to document that it doesn't work in
1800    future.
1801    
1802    18. Added an error diagnosis for escapes that PCRE does not support: these are
1803    \L, \l, \N, \P, \p, \U, \u, and \X.
1804    
1805    19. Although correctly diagnosing a missing ']' in a character class, PCRE was
1806    reading past the end of the pattern in cases such as /[abcd/.
1807    
1808    20. PCRE was getting more memory than necessary for patterns with classes that
1809    contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
1810    
1811    21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
1812    compiling PCRE for use with Virtual Pascal.
1813    
1814    22. Small fix to the Makefile to make it work properly if the build is done
1815    outside the source tree.
1816    
1817    23. Added a new extension: a condition to go with recursion. If a conditional
1818    subpattern starts with (?(R) the "true" branch is used if recursion has
1819    happened, whereas the "false" branch is used only at the top level.
1820    
1821    24. When there was a very long string of literal characters (over 255 bytes
1822    without UTF support, over 250 bytes with UTF support), the computation of how
1823    much memory was required could be incorrect, leading to segfaults or other
1824    strange effects.
1825    
1826    25. PCRE was incorrectly assuming anchoring (either to start of subject or to
1827    start of line for a non-DOTALL pattern) when a pattern started with (.*) and
1828    there was a subsequent back reference to those brackets. This meant that, for
1829    example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
1830    possible to check for precisely this case. All we can do is abandon the
1831    optimization if .* occurs inside capturing brackets when there are any back
1832    references whatsoever. (See below for a better fix that came later.)
1833    
1834    26. The handling of the optimization for finding the first character of a
1835    non-anchored pattern, and for finding a character that is required later in the
1836    match were failing in some cases. This didn't break the matching; it just
1837    failed to optimize when it could. The way this is done has been re-implemented.
1838    
1839    27. Fixed typo in error message for invalid (?R item (it said "(?p").
1840    
1841    28. Added a new feature that provides some of the functionality that Perl
1842    provides with (?{...}). The facility is termed a "callout". The way it is done
1843    in PCRE is for the caller to provide an optional function, by setting
1844    pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
1845    global variable. By default it is unset, which disables all calling out. To get
1846    the function called, the regex must include (?C) at appropriate points. This
1847    is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
1848    This provides a means of identifying different callout points. When PCRE
1849    reaches such a point in the regex, if pcre_callout has been set, the external
1850    function is called. It is provided with data in a structure called
1851    pcre_callout_block, which is defined in pcre.h. If the function returns 0,
1852    matching continues; if it returns a non-zero value, the match at the current
1853    point fails. However, backtracking will occur if possible. [This was changed
1854    later and other features added - see item 49 below.]
1855    
1856    29. pcretest is upgraded to test the callout functionality. It provides a
1857    callout function that displays information. By default, it shows the start of
1858    the match and the current position in the text. There are some new data escapes
1859    to vary what happens:
1860    
1861        \C+         in addition, show current contents of captured substrings
1862        \C-         do not supply a callout function
1863        \C!n        return 1 when callout number n is reached
1864        \C!n!m      return 1 when callout number n is reached for the mth time
1865    
1866    30. If pcregrep was called with the -l option and just a single file name, it
1867    output "<stdin>" if a match was found, instead of the file name.
1868    
1869    31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
1870    slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
1871    pcre_exec(). This saves a malloc/free per call. The default value of
1872    POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
1873    when configuring.
1874    
1875    32. The default maximum size of a compiled pattern is 64K. There have been a
1876    few cases of people hitting this limit. The code now uses macros to handle the
1877    storing of links as offsets within the compiled pattern. It defaults to 2-byte
1878    links, but this can be changed to 3 or 4 bytes by --with-link-size when
1879    configuring. Tests 2 and 5 work only with 2-byte links because they output
1880    debugging information about compiled patterns.
1881    
1882    33. Internal code re-arrangements:
1883    
1884    (a) Moved the debugging function for printing out a compiled regex into
1885        its own source file (printint.c) and used #include to pull it into
1886        pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
1887        separate copies.
1888    
1889    (b) Defined the list of op-code names for debugging as a macro in
1890        internal.h so that it is next to the definition of the opcodes.
1891    
1892    (c) Defined a table of op-code lengths for simpler skipping along compiled
1893        code. This is again a macro in internal.h so that it is next to the
1894        definition of the opcodes.
1895    
1896    34. Added support for recursive calls to individual subpatterns, along the
1897    lines of Robin Houston's patch (but implemented somewhat differently).
1898    
1899    35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
1900    allow it to read and process whole directories in Win32. This code was
1901    contributed by Lionel Fourquaux; it has not been tested by me.
1902    
1903    36. Added support for named subpatterns. The Python syntax (?P<name>...) is
1904    used to name a group. Names consist of alphanumerics and underscores, and must
1905    be unique. Back references use the syntax (?P=name) and recursive calls use
1906    (?P>name) which is a PCRE extension to the Python extension. Groups still have
1907    numbers. The function pcre_fullinfo() can be used after compilation to extract
1908    a name/number map. There are three relevant calls:
1909    
1910      PCRE_INFO_NAMEENTRYSIZE        yields the size of each entry in the map
1911      PCRE_INFO_NAMECOUNT            yields the number of entries
1912      PCRE_INFO_NAMETABLE            yields a pointer to the map.
1913    
1914    The map is a vector of fixed-size entries. The size of each entry depends on
1915    the length of the longest name used. The first two bytes of each entry are the
1916    group number, most significant byte first. There follows the corresponding
1917    name, zero terminated. The names are in alphabetical order.
1918    
1919    37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
1920    case instead of 255. Making it the same both with and without UTF-8 support
1921    means that the same test output works with both.
1922    
1923    38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
1924    calling malloc() with a zero argument.
1925    
1926    39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
1927    optimization. I've improved things by keeping a bitmap of backreferences with
1928    numbers 1-31 so that if .* occurs inside capturing brackets that are not in
1929    fact referenced, the optimization can be applied. It is unlikely that a
1930    relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
1931    the match to follow \n) will appear inside brackets with a number greater than
1932    31, but if it does, any back reference > 31 suppresses the optimization.
1933    
1934    40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
1935    of disabling numbered capturing parentheses. Any opening parenthesis that is
1936    not followed by ? behaves as if it were followed by ?: but named parentheses
1937    can still be used for capturing (and they will acquire numbers in the usual
1938    way).
1939    
1940    41. Redesigned the return codes from the match() function into yes/no/error so
1941    that errors can be passed back from deep inside the nested calls. A malloc
1942    failure while inside a recursive subpattern call now causes the
1943    PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
1944    
1945    42. It is now possible to set a limit on the number of times the match()
1946    function is called in a call to pcre_exec(). This facility makes it possible to
1947    limit the amount of recursion and backtracking, though not in a directly
1948    obvious way, because the match() function is used in a number of different
1949    circumstances. The count starts from zero for each position in the subject
1950    string (for non-anchored patterns). The default limit is, for compatibility, a
1951    large number, namely 10 000 000. You can change this in two ways:
1952    
1953    (a) When configuring PCRE before making, you can use --with-match-limit=n
1954        to set a default value for the compiled library.
1955    
1956    (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
1957        a different value is set. See 45 below.
1958    
1959    If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
1960    
1961    43. Added a new function pcre_config(int, void *) to enable run-time extraction
1962    of things that can be changed at compile time. The first argument specifies
1963    what is wanted and the second points to where the information is to be placed.
1964    The current list of available information is:
1965    
1966      PCRE_CONFIG_UTF8
1967    
1968    The output is an integer that is set to one if UTF-8 support is available;
1969    otherwise it is set to zero.
1970    
1971      PCRE_CONFIG_NEWLINE
1972    
1973    The output is an integer that it set to the value of the code that is used for
1974    newline. It is either LF (10) or CR (13).
1975    
1976      PCRE_CONFIG_LINK_SIZE
1977    
1978    The output is an integer that contains the number of bytes used for internal
1979    linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
1980    
1981      PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
1982    
1983    The output is an integer that contains the threshold above which the POSIX
1984    interface uses malloc() for output vectors. See item 31 above.
1985    
1986      PCRE_CONFIG_MATCH_LIMIT
1987    
1988    The output is an unsigned integer that contains the default limit of the number
1989    of match() calls in a pcre_exec() execution. See 42 above.
1990    
1991    44. pcretest has been upgraded by the addition of the -C option. This causes it
1992    to extract all the available output from the new pcre_config() function, and to
1993    output it. The program then exits immediately.
1994    
1995    45. A need has arisen to pass over additional data with calls to pcre_exec() in
1996    order to support additional features. One way would have been to define
1997    pcre_exec2() (for example) with extra arguments, but this would not have been
1998    extensible, and would also have required all calls to the original function to
1999    be mapped to the new one. Instead, I have chosen to extend the mechanism that
2000    is used for passing in "extra" data from pcre_study().
2001    
2002    The pcre_extra structure is now exposed and defined in pcre.h. It currently
2003    contains the following fields:
2004    
2005      flags         a bitmap indicating which of the following fields are set
2006      study_data    opaque data from pcre_study()
2007      match_limit   a way of specifying a limit on match() calls for a specific
2008                      call to pcre_exec()
2009      callout_data  data for callouts (see 49 below)
2010    
2011    The flag bits are also defined in pcre.h, and are
2012    
2013      PCRE_EXTRA_STUDY_DATA
2014      PCRE_EXTRA_MATCH_LIMIT
2015      PCRE_EXTRA_CALLOUT_DATA
2016    
2017    The pcre_study() function now returns one of these new pcre_extra blocks, with
2018    the actual study data pointed to by the study_data field, and the
2019    PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
2020    before. That is, this change is entirely upwards-compatible and requires no
2021    change to existing code.
2022    
2023    If you want to pass in additional data to pcre_exec(), you can either place it
2024    in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2025    block.
2026    
2027    46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2028    data string contains the escape sequence \M, pcretest calls pcre_exec() several
2029    times with different match limits, until it finds the minimum value needed for
2030    pcre_exec() to complete. The value is then output. This can be instructive; for
2031    most simple matches the number is quite small, but for pathological cases it
2032    gets very large very quickly.
2033    
2034    47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2035    returns the size of the data block pointed to by the study_data field in a
2036    pcre_extra block, that is, the value that was passed as the argument to
2037    pcre_malloc() when PCRE was getting memory in which to place the information
2038    created by pcre_study(). The fourth argument should point to a size_t variable.
2039    pcretest has been extended so that this information is shown after a successful
2040    pcre_study() call when information about the compiled regex is being displayed.
2041    
2042    48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2043    because what follows is always an absolute path. (Later: it turns out that this
2044    is more than cosmetic for MinGW, because it doesn't like empty path
2045    components.)
2046    
2047    49. Some changes have been made to the callout feature (see 28 above):
2048    
2049    (i)  A callout function now has three choices for what it returns:
2050    
2051           0  =>  success, carry on matching
2052         > 0  =>  failure at this point, but backtrack if possible
2053         < 0  =>  serious error, return this value from pcre_exec()
2054    
2055         Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2056         values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2057         "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2058         use by callout functions. It will never be used by PCRE itself.
2059    
2060    (ii) The pcre_extra structure (see 45 above) has a void * field called
2061         callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2062         pcre_callout_block structure has a field of the same name. The contents of
2063         the field passed in the pcre_extra structure are passed to the callout
2064         function in the corresponding field in the callout block. This makes it
2065         easier to use the same callout-containing regex from multiple threads. For
2066         testing, the pcretest program has a new data escape
2067    
2068           \C*n        pass the number n (may be negative) as callout_data
2069    
2070         If the callout function in pcretest receives a non-zero value as
2071         callout_data, it returns that value.
2072    
2073    50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2074    there were some redundant $(CFLAGS) in commands that are now specified as
2075    $(LINK), which already includes $(CFLAGS).
2076    
2077    51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2078    has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2079    with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2080    one-byte characters throughout. Note that case-insensitive matching applies
2081    only to characters whose values are less than 256. PCRE doesn't support the
2082    notion of cases for higher-valued characters.
2083    
2084    (i)   A character class whose characters are all within 0-255 is handled as
2085          a bit map, and the map is inverted for negative classes. Previously, a
2086          character > 255 always failed to match such a class; however it should
2087          match if the class was a negative one (e.g. [^ab]). This has been fixed.
2088    
2089    (ii)  A negated character class with a single character < 255 is coded as
2090          "not this character" (OP_NOT). This wasn't working properly when the test
2091          character was multibyte, either singly or repeated.
2092    
2093    (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2094          mode, for example: \x{100}{2,3}.
2095    
2096    (iv)  The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2097          singly or repeated) now correctly test multibyte characters. However,
2098          PCRE doesn't recognize any characters with values greater than 255 as
2099          digits, spaces, or word characters. Such characters always match \D, \S,
2100          and \W, and never match \d, \s, or \w.
2101    
2102    (v)   Classes may now contain characters and character ranges with values
2103          greater than 255. For example: [ab\x{100}-\x{400}].
2104    
2105    (vi)  pcregrep now has a --utf-8 option (synonym -u) which makes it call
2106          PCRE in UTF-8 mode.
2107    
2108    52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2109    PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2110    retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2111    value.)
2112    
2113    53. The single man page has become too large. I have therefore split it up into
2114    a number of separate man pages. These also give rise to individual HTML pages;
2115    these are now put in a separate directory, and there is an index.html page that
2116    lists them all. Some hyperlinking between the pages has been installed.
2117    
2118    54. Added convenience functions for handling named capturing parentheses.
2119    
2120    55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2121    aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2122    true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2123    are faulted.
2124    
2125    56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2126    calling configure. These values are used when compiling the dftables.c program
2127    which is run to generate the source of the default character tables. They
2128    default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2129    you will need to set these values.
2130    
2131    57. Updated the building process for Windows DLL, as provided by Fred Cox.
2132    
2133    
2134    Version 3.9 02-Jan-02
2135    ---------------------
2136    
2137    1. A bit of extraneous text had somehow crept into the pcregrep documentation.
2138    
2139    2. If --disable-static was given, the building process failed when trying to
2140    build pcretest and pcregrep. (For some reason it was using libtool to compile
2141    them, which is not right, as they aren't part of the library.)
2142    
2143    
2144    Version 3.8 18-Dec-01
2145    ---------------------
2146    
2147    1. The experimental UTF-8 code was completely screwed up. It was packing the
2148    bytes in the wrong order. How dumb can you get?
2149    
2150    
2151    Version 3.7 29-Oct-01
2152    ---------------------
2153    
2154    1. In updating pcretest to check change 1 of version 3.6, I screwed up.
2155    This caused pcretest, when used on the test data, to segfault. Unfortunately,
2156    this didn't happen under Solaris 8, where I normally test things.
2157    
2158    2. The Makefile had to be changed to make it work on BSD systems, where 'make'
2159    doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
2160    isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
2161    this fix an hour or so after the initial 3.7 release.)
2162    
2163    
2164    Version 3.6 23-Oct-01
2165    ---------------------
2166    
2167    1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
2168    offsets passed as NULL with zero offset count.
2169    
2170    2. The config.guess and config.sub files had not been updated when I moved to
2171    the latest autoconf.
2172    
2173    
2174    Version 3.5 15-Aug-01
2175    ---------------------
2176    
2177    1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2178    had been forgotten.
2179    
2180    2. By using declared but undefined structures, we can avoid using "void"
2181    definitions in pcre.h while keeping the internal definitions of the structures
2182    private.
2183    
2184    3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2185    user point of view, this means that both static and shared libraries are built
2186    by default, but this can be individually controlled. More of the work of
2187    handling this static/shared cases is now inside libtool instead of PCRE's make
2188    file.
2189    
2190    4. The pcretest utility is now installed along with pcregrep because it is
2191    useful for users (to test regexs) and by doing this, it automatically gets
2192    relinked by libtool. The documentation has been turned into a man page, so
2193    there are now .1, .txt, and .html versions in /doc.
2194    
2195    5. Upgrades to pcregrep:
2196       (i)   Added long-form option names like gnu grep.
2197       (ii)  Added --help to list all options with an explanatory phrase.
2198       (iii) Added -r, --recursive to recurse into sub-directories.
2199       (iv)  Added -f, --file to read patterns from a file.
2200    
2201    6. pcre_exec() was referring to its "code" argument before testing that
2202    argument for NULL (and giving an error if it was NULL).
2203    
2204    7. Upgraded Makefile.in to allow for compiling in a different directory from
2205    the source directory.
2206    
2207    8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2208    options bits, the pointer it was passed was to an int instead of to an unsigned
2209    long int. This mattered only on 64-bit systems.
2210    
2211    9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2212    generated) instead of pcre.in, which it its source. Also made the same change
2213    in several of the .c files.
2214    
2215    10. A new release of gcc defines printf() as a macro, which broke pcretest
2216    because it had an ifdef in the middle of a string argument for printf(). Fixed
2217    by using separate calls to printf().
2218    
2219    11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2220    script, to force use of CR or LF instead of \n in the source. On non-Unix
2221    systems, the value can be set in config.h.
2222    
2223    12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2224    absolute limit. Changed the text of the error message to make this clear, and
2225    likewise updated the man page.
2226    
2227    13. The limit of 99 on the number of capturing subpatterns has been removed.
2228    The new limit is 65535, which I hope will not be a "real" limit.
2229    
2230    
2231    Version 3.4 22-Aug-00
2232    ---------------------
2233    
2234    1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2235    
2236    2. Diagnose condition (?(0) as an error instead of crashing on matching.
2237    
2238    
2239    Version 3.3 01-Aug-00
2240    ---------------------
2241    
2242    1. If an octal character was given, but the value was greater than \377, it
2243    was not getting masked to the least significant bits, as documented. This could
2244    lead to crashes in some systems.
2245    
2246    2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2247    the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2248    
2249    3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2250    These just pass their arguments on to (pcre_free)(), but they are provided
2251    because some uses of PCRE bind it to non-C systems that can call its functions,
2252    but cannot call free() or pcre_free() directly.
2253    
2254    4. Add "make test" as a synonym for "make check". Corrected some comments in
2255    the Makefile.
2256    
2257    5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2258    Makefile.
2259    
2260    6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2261    command called pgrep for grepping around the active processes.
2262    
2263    7. Added the beginnings of support for UTF-8 character strings.
2264    
2265    8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2266    RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2267    the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2268    out for the ar command.)
2269    
2270    
2271    Version 3.2 12-May-00
2272    ---------------------
2273    
2274    This is purely a bug fixing release.
2275    
2276    1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
2277    of ZA. This was just one example of several cases that could provoke this bug,
2278    which was introduced by change 9 of version 2.00. The code for breaking
2279    infinite loops after an iteration that matches an empty string was't working
2280    correctly.
2281    
2282    2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
2283    when matched against abbab (for example). After matching an empty string, it
2284    wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
2285    caused it to match further down the string than it should.
2286    
2287    3. The code contained an inclusion of sys/types.h. It isn't clear why this
2288    was there because it doesn't seem to be needed, and it causes trouble on some
2289    systems, as it is not a Standard C header. It has been removed.
2290    
2291    4. Made 4 silly changes to the source to avoid stupid compiler warnings that
2292    were reported on the Macintosh. The changes were from
2293    
2294      while ((c = *(++ptr)) != 0 && c != '\n');
2295    to
2296      while ((c = *(++ptr)) != 0 && c != '\n') ;
2297    
2298    Totally extraordinary, but if that's what it takes...
2299    
2300    5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2301    available. Added HAVE_BCOPY and an autoconf test for it; if neither
2302    HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2303    assumes the way PCRE uses memmove() (always moving upwards).
2304    
2305    6. PCRE is being used in one environment where strchr() is not available. There
2306    was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2307    faster code anyway.
2308    
2309    
2310    Version 3.1 09-Feb-00
2311    ---------------------
2312    
2313    The only change in this release is the fixing of some bugs in Makefile.in for
2314    the "install" target:
2315    
2316    (1) It was failing to install pcreposix.h.
2317    
2318    (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2319    
2320    
2321    Version 3.0 01-Feb-00
2322    ---------------------
2323    
2324    1. Add support for the /+ modifier to perltest (to output $` like it does in
2325    pcretest).
2326    
2327    2. Add support for the /g modifier to perltest.
2328    
2329    3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2330    matches null strings.
2331    
2332    4. Fix perltest so that it doesn't do unwanted things when fed an empty
2333    pattern. Perl treats empty patterns specially - it reuses the most recent
2334    pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2335    effect.
2336    
2337    5. The POSIX interface was broken in that it was just handing over the POSIX
2338    captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2339    required a bigger vector, with some working space on the end. This means that
2340    the POSIX wrapper now has to get and free some memory, and copy the results.
2341    
2342    6. Added some simple autoconf support, placing the test data and the
2343    documentation in separate directories, re-organizing some of the
2344    information files, and making it build pcre-config (a GNU standard). Also added
2345    libtool support for building PCRE as a shared library, which is now the
2346    default.
2347    
2348    7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2349    09 are not valid octal constants. Single digits will be used for minor values
2350    less than 10.
2351    
2352    8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2353    existing programs that set these in the POSIX interface can use PCRE without
2354    modification.
2355    
2356    9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2357    return all that pcre_info() returns, plus additional data. The pcre_info()
2358    function is retained for compatibility, but is considered to be obsolete.
2359    
2360    10. Added experimental recursion feature (?R) to handle one common case that
2361    Perl 5.6 will be able to do with (?p{...}).
2362    
2363    11. Added support for POSIX character classes like [:alpha:], which Perl is
2364    adopting.
2365    
2366    
2367    Version 2.08 31-Aug-99
2368    ----------------------
2369    
2370    1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2371    trying to match at the startoffset position, but instead was moving forward to
2372    the next newline as if a previous match had failed.
2373    
2374    2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2375    and could get into a loop if a null string was matched other than at the start
2376    of the subject.
2377    
2378    3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2379    be distinguished at compile time, and for completeness also added PCRE_DATE.
2380    
2381    5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2382    in GnuWin32 environments.
2383    
2384    
2385    Version 2.07 29-Jul-99
2386    ----------------------
2387    
2388    1. The documentation is now supplied in plain text form and HTML as well as in
2389    the form of man page sources.
2390    
2391    2. C++ compilers don't like assigning (void *) values to other pointer types.
2392    In particular this affects malloc(). Although there is no problem in Standard
2393    C, I've put in casts to keep C++ compilers happy.
2394    
2395    3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2396    should be (const char *).
2397    
2398    4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2399    be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2400    However, I haven't made this a standard facility. The documentation doesn't
2401    mention it, and the Makefile doesn't support it.
2402    
2403    5. The Makefile now contains an "install" target, with editable destinations at
2404    the top of the file. The pcretest program is not installed.
2405    
2406    6. pgrep -V now gives the PCRE version number and date.
2407    
2408    7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2409    causing the entire string to be ignored, instead of just the last character.
2410    
2411    8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2412    non-matching string, it can take a very, very long time, even for strings of
2413    quite modest length, because of the nested recursion. PCRE now does better in
2414    some of these cases. It does this by remembering the last required literal
2415    character in the pattern, and pre-searching the subject to ensure it is present
2416    before running the real match. In other words, it applies a heuristic to detect
2417    some types of certain failure quickly, and in the above example, if presented
2418    with a string that has no trailing " it gives "no match" very quickly.
2419    
2420    9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2421    other alternatives are tried instead.
2422    
2423    
2424    Version 2.06 09-Jun-99
2425    ----------------------
2426    
2427    1. Change pcretest's output for amount of store used to show just the code
2428    space, because the remainder (the data block) varies in size between 32-bit and
2429    64-bit systems.
2430    
2431    2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2432    start matching at. This allows lookbehinds to work when searching for multiple
2433    occurrences in a string.
2434    
2435    3. Added additional options to pcretest for testing multiple occurrences:
2436    
2437       /+   outputs the rest of the string that follows a match
2438       /g   loops for multiple occurrences, using the new startoffset argument
2439       /G   loops for multiple occurrences by passing an incremented pointer
2440    
2441    4. PCRE wasn't doing the "first character" optimization for patterns starting
2442    with \b or \B, though it was doing it for other lookbehind assertions. That is,
2443    it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2444    the letter 'x'. On long subject strings, this gives a significant speed-up.
2445    
2446    
2447    Version 2.05 21-Apr-99
2448    ----------------------
2449    
2450    1. Changed the type of magic_number from int to long int so that it works
2451    properly on 16-bit systems.
2452    
2453    2. Fixed a bug which caused patterns starting with .* not to work correctly
2454    when the subject string contained newline characters. PCRE was assuming
2455    anchoring for such patterns in all cases, which is not correct because .* will
2456    not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
2457    DOTALL is set at top level; otherwise it knows that patterns starting with .*
2458    must be retried after every newline in the subject.
2459    
2460    
2461    Version 2.04 18-Feb-99
2462    ----------------------
2463    
2464    1. For parenthesized subpatterns with repeats whose minimum was zero, the
2465    computation of the store needed to hold the pattern was incorrect (too large).
2466    If such patterns were nested a few deep, this could multiply and become a real
2467    problem.
2468    
2469    2. Added /M option to pcretest to show the memory requirement of a specific
2470    pattern. Made -m a synonym of -s (which does this globally) for compatibility.
2471    
2472    3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
2473    compiled in such a way that the backtracking after subsequent failure was
2474    pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
2475    ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
2476    
2477    
2478    Version 2.03 02-Feb-99
2479    ----------------------
2480    
2481    1. Fixed typo and small mistake in man page.
2482    
2483    2. Added 4th condition (GPL supersedes if conflict) and created separate
2484    LICENCE file containing the conditions.
2485    
2486    3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
2487    Perl, that is the internal \ allows the delimiter to be included in the
2488    pattern. Locked out the use of \ as a delimiter. If \ immediately follows
2489    the final delimiter, add \ to the end of the pattern (to test the error).
2490    
2491    4. Added the convenience functions for extracting substrings after a successful
2492    match. Updated pcretest to make it able to test these functions.
2493    
2494    
2495    Version 2.02 14-Jan-99
2496    ----------------------
2497    
2498    1. Initialized the working variables associated with each extraction so that
2499    their saving and restoring doesn't refer to uninitialized store.
2500    
2501    2. Put dummy code into study.c in order to trick the optimizer of the IBM C
2502    compiler for OS/2 into generating correct code. Apparently IBM isn't going to
2503    fix the problem.
2504    
2505    3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
2506    calls, and wasn't printing the correct value for compiling calls. Increased the
2507    default value of LOOPREPEAT, and the number of significant figures in the
2508    times.
2509    
2510    4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
2511    
2512    5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
2513    a building problem on Windows NT with a FAT file system.
2514    
2515    
2516    Version 2.01 21-Oct-98
2517    ----------------------
2518    
2519    1. Changed the API for pcre_compile() to allow for the provision of a pointer
2520    to character tables built by pcre_maketables() in the current locale. If NULL
2521    is passed, the default tables are used.
2522    
2523    
2524  Version 2.00 24-Sep-98  Version 2.00 24-Sep-98
2525  ----------------------  ----------------------

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