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revision 69 by nigel, Sat Feb 24 21:40:18 2007 UTC revision 207 by ph10, Mon Aug 6 09:32:14 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.3 05-Jul-07
5    ---------------------
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:
13          #include "pcre.h"
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.
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.
27     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
29     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
30        in debug output.
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.
35     6. ESC_K was left out of the EBCDIC table.
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.
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.
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.
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.
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.
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.
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".
92    Version 7.2 19-Jun-07
93    ---------------------
95     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
96        which is apparently normally available under Windows.
98     2. Re-jig the pcregrep tests with different newline settings in an attempt
99        to make them independent of the local environment's newline setting.
101     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
103     4. Some of the "internals" tests were previously cut out when the link size
104        was not 2, because the output contained actual offsets. The recent new
105        "Z" feature of pcretest means that these can be cut out, making the tests
106        usable with all link sizes.
108     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
109        stack recursion. This gives a massive performance boost under BSD, but just
110        a small improvement under Linux. However, it saves one field in the frame
111        in all cases.
113     6. Added more features from the forthcoming Perl 5.10:
115        (a) (?-n) (where n is a string of digits) is a relative subroutine or
116            recursion call. It refers to the nth most recently opened parentheses.
118        (b) (?+n) is also a relative subroutine call; it refers to the nth next
119            to be opened parentheses.
121        (c) Conditions that refer to capturing parentheses can be specified
122            relatively, for example, (?(-2)... or (?(+3)...
124        (d) \K resets the start of the current match so that everything before
125            is not part of it.
127        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
129        (f) \g{name} is another synonym - part of Perl 5.10's unification of
130            reference syntax.
132        (g) (?| introduces a group in which the numbering of parentheses in each
133            alternative starts with the same number.
135        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
137     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
140     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
141        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
142        for detecting groups that can match an empty string.
144     9. A pattern with a very large number of alternatives (more than several
145        hundred) was running out of internal workspace during the pre-compile
146        phase, where pcre_compile() figures out how much memory will be needed. A
147        bit of new cunning has reduced the workspace needed for groups with
148        alternatives. The 1000-alternative test pattern now uses 12 bytes of
149        workspace instead of running out of the 4096 that are available.
151    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
153    11. Applied patch from Google to remove an optimization that didn't quite work.
154        The report of the bug said:
156          pcrecpp::RE("a*").FullMatch("aaa") matches, while
157          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
158          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
160    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
161        it matched the wrong number of bytes.
164    Version 7.1 24-Apr-07
165    ---------------------
167     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
168        that is more "standard", making use of automake and other Autotools. There
169        is some re-arrangement of the files and adjustment of comments consequent
170        on this.
172     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
173        for recursive directory scanning broke on some systems because the files
174        are not scanned in any specific order and on different systems the order
175        was different. A call to "sort" has been inserted into RunGrepTest for the
176        approprate test as a short-term fix. In the longer term there may be an
177        alternative.
179     3. I had an email from Eric Raymond about problems translating some of PCRE's
180        man pages to HTML (despite the fact that I distribute HTML pages, some
181        people do their own conversions for various reasons). The problems
182        concerned the use of low-level troff macros .br and .in. I have therefore
183        removed all such uses from the man pages (some were redundant, some could
184        be replaced by .nf/.fi pairs). The 132html script that I use to generate
185        HTML has been updated to handle .nf/.fi and to complain if it encounters
186        .br or .in.
188     4. Updated comments in configure.ac that get placed in config.h.in and also
189        arranged for config.h to be included in the distribution, with the name
190        config.h.generic, for the benefit of those who have to compile without
191        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
193     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
194        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
195        makevp.bat for the current PCRE, using the additional files
196        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
198     6. A Windows user reported a minor discrepancy with test 2, which turned out
199        to be caused by a trailing space on an input line that had got lost in his
200        copy. The trailing space was an accident, so I've just removed it.
202     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
203        that is needed.
205     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
206        as "const" (a) because they are and (b) because it helps the PHP
207        maintainers who have recently made a script to detect big data structures
208        in the php code that should be moved to the .rodata section. I remembered
209        to update Builducptable as well, so it won't revert if ucptable.h is ever
210        re-created.
212     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
213        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
214        order to be able to cut out the UTF-8 tables in the latter when UTF-8
215        support is not required. This saves 1.5-2K of code, which is important in
216        some applications.
218        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
219        so as not to refer to the tables, even though these functions will never be
220        called when UTF-8 support is disabled. Otherwise there are problems with a
221        shared library.
223    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
225        (a) It was defining its arguments as char * instead of void *.
227        (b) It was assuming that all moves were upwards in memory; this was true
228            a long time ago when I wrote it, but is no longer the case.
230        The emulated memove() is provided for those environments that have neither
231        memmove() nor bcopy(). I didn't think anyone used it these days, but that
232        is clearly not the case, as these two bugs were recently reported.
234    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
235        and Detrail to create the HTML documentation, the .txt form of the man
236        pages, and it removes trailing spaces from listed files. It also creates
237        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
238        case, it wraps all the #defines with #ifndefs. This script should be run
239        before "make dist".
241    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
242        with Unicode property support.
244        (a) For a maximizing quantifier, if the two different cases of the
245            character were of different lengths in their UTF-8 codings (there are
246            some cases like this - I found 11), and the matching function had to
247            back up over a mixture of the two cases, it incorrectly assumed they
248            were both the same length.
250        (b) When PCRE was configured to use the heap rather than the stack for
251            recursion during matching, it was not correctly preserving the data for
252            the other case of a UTF-8 character when checking ahead for a match
253            while processing a minimizing repeat. If the check also involved
254            matching a wide character, but failed, corruption could cause an
255            erroneous result when trying to check for a repeat of the original
256            character.
258    13. Some tidying changes to the testing mechanism:
260        (a) The RunTest script now detects the internal link size and whether there
261            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
262            values substituted by "configure". (The RunGrepTest script already did
263            this for UTF-8.) The configure.ac script no longer substitutes the
264            relevant variables.
266        (b) The debugging options /B and /D in pcretest show the compiled bytecode
267            with length and offset values. This means that the output is different
268            for different internal link sizes. Test 2 is skipped for link sizes
269            other than 2 because of this, bypassing the problem. Unfortunately,
270            there was also a test in test 3 (the locale tests) that used /B and
271            failed for link sizes other than 2. Rather than cut the whole test out,
272            I have added a new /Z option to pcretest that replaces the length and
273            offset values with spaces. This is now used to make test 3 independent
274            of link size. (Test 2 will be tidied up later.)
276    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
277        segmentation fault instead of returning the appropriate error message.
279    15. In multiline mode when the newline sequence was set to "any", the pattern
280        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
281        This doesn't seem right; it now treats the CRLF combination as the line
282        ending, and so does not match in that case. It's only a pattern such as ^$
283        that would hit this one: something like ^ABC$ would have failed after \r
284        and then tried again after \r\n.
286    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
287        in an attempt to make files that differ only in their line terminators
288        compare equal. This works on Linux.
290    17. Under certain error circumstances pcregrep might try to free random memory
291        as it exited. This is now fixed, thanks to valgrind.
293    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
294        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
295        was because its rules for how to advance for /g after matching an empty
296        string at the end of a line did not allow for this case. They now check for
297        it specially.
299    20. pcretest is supposed to handle patterns and data of any length, by
300        extending its buffers when necessary. It was getting this wrong when the
301        buffer for a data line had to be extended.
303    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
304        CRLF as a newline sequence.
306    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
307        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
308        I have nevertheless tidied it up.
310    23. Added some casts to kill warnings from HP-UX ia64 compiler.
312    24. Added a man page for pcre-config.
315    Version 7.0 19-Dec-06
316    ---------------------
318     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
319        moving to gcc 4.1.1.
321     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
322        sys/time.h, which is documented as needed for this function. It doesn't
323        seem to matter on Linux, but it showed up on some releases of OS X.
325     3. It seems that there are systems where bytes whose values are greater than
326        127 match isprint() in the "C" locale. The "C" locale should be the
327        default when a C program starts up. In most systems, only ASCII printing
328        characters match isprint(). This difference caused the output from pcretest
329        to vary, making some of the tests fail. I have changed pcretest so that:
331        (a) When it is outputting text in the compiled version of a pattern, bytes
332            other than 32-126 are always shown as hex escapes.
334        (b) When it is outputting text that is a matched part of a subject string,
335            it does the same, unless a different locale has been set for the match
336            (using the /L modifier). In this case, it uses isprint() to decide.
338     4. Fixed a major bug that caused incorrect computation of the amount of memory
339        required for a compiled pattern when options that changed within the
340        pattern affected the logic of the preliminary scan that determines the
341        length. The relevant options are -x, and -i in UTF-8 mode. The result was
342        that the computed length was too small. The symptoms of this bug were
343        either the PCRE error "internal error: code overflow" from pcre_compile(),
344        or a glibc crash with a message such as "pcretest: free(): invalid next
345        size (fast)". Examples of patterns that provoked this bug (shown in
346        pcretest format) are:
348          /(?-x: )/x
349          /(?x)(?-x: \s*#\s*)/
350          /((?i)[\x{c0}])/8
351          /(?i:[\x{c0}])/8
353        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
354        is now done differently.
356     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
357        wrapper classes; (b) implement a new function in the C++ scanner that is
358        more efficient than the old way of doing things because it avoids levels of
359        recursion in the regex matching; (c) add a paragraph to the documentation
360        for the FullMatch() function.
362     6. The escape sequence \n was being treated as whatever was defined as
363        "newline". Not only was this contrary to the documentation, which states
364        that \n is character 10 (hex 0A), but it also went horribly wrong when
365        "newline" was defined as CRLF. This has been fixed.
367     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
368        was being set to -1 for the "end of line" case (supposedly a value that no
369        character can have). Though this value is never used (the check for end of
370        line is "zero bytes in current character"), it caused compiler complaints.
371        I've changed it to 0xffffffff.
373     8. In pcre_version.c, the version string was being built by a sequence of
374        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
375        string (as it is for production releases) called a macro with an empty
376        argument. The C standard says the result of this is undefined. The gcc
377        compiler treats it as an empty string (which was what was wanted) but it is
378        reported that Visual C gives an error. The source has been hacked around to
379        avoid this problem.
381     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
382        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
383        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
384        of them did).
386    10. Originally, pcretest opened its input and output without "b"; then I was
387        told that "b" was needed in some environments, so it was added for release
388        5.0 to both the input and output. (It makes no difference on Unix-like
389        systems.) Later I was told that it is wrong for the input on Windows. I've
390        now abstracted the modes into two macros, to make it easier to fiddle with
391        them, and removed "b" from the input mode under Windows.
393    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
395    12. Added -help and --help to pcretest as an official way of being reminded
396        of the options.
398    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
399        and pcrecpp.cc because they annoy compilers at high warning levels.
401    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
403    15. Fixed an occurrence of == in configure.ac that should have been = (shell
404        scripts are not C programs :-) and which was not noticed because it works
405        on Linux.
407    16. pcretest is supposed to handle any length of pattern and data line (as one
408        line or as a continued sequence of lines) by extending its input buffer if
409        necessary. This feature was broken for very long pattern lines, leading to
410        a string of junk being passed to pcre_compile() if the pattern was longer
411        than about 50K.
413    17. I have done a major re-factoring of the way pcre_compile() computes the
414        amount of memory needed for a compiled pattern. Previously, there was code
415        that made a preliminary scan of the pattern in order to do this. That was
416        OK when PCRE was new, but as the facilities have expanded, it has become
417        harder and harder to keep it in step with the real compile phase, and there
418        have been a number of bugs (see for example, 4 above). I have now found a
419        cunning way of running the real compile function in a "fake" mode that
420        enables it to compute how much memory it would need, while actually only
421        ever using a few hundred bytes of working memory and without too many
422        tests of the mode. This should make future maintenance and development
423        easier. A side effect of this work is that the limit of 200 on the nesting
424        depth of parentheses has been removed (though this was never a serious
425        limitation, I suspect). However, there is a downside: pcre_compile() now
426        runs more slowly than before (30% or more, depending on the pattern). I
427        hope this isn't a big issue. There is no effect on runtime performance.
429    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
430        newline (only possible for the last line of a file) and it was a
431        pattern that set a locale (followed by /Lsomething), pcretest crashed.
433    19. Added additional timing features to pcretest. (1) The -tm option now times
434        matching only, not compiling. (2) Both -t and -tm can be followed, as a
435        separate command line item, by a number that specifies the number of
436        repeats to use when timing. The default is 50000; this gives better
437        precision, but takes uncomfortably long for very large patterns.
439    20. Extended pcre_study() to be more clever in cases where a branch of a
440        subpattern has no definite first character. For example, (a*|b*)[cd] would
441        previously give no result from pcre_study(). Now it recognizes that the
442        first character must be a, b, c, or d.
444    21. There was an incorrect error "recursive call could loop indefinitely" if
445        a subpattern (or the entire pattern) that was being tested for matching an
446        empty string contained only one non-empty item after a nested subpattern.
447        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
448        incorrectly, because the \d was being skipped in the check.
450    22. The pcretest program now has a new pattern option /B and a command line
451        option -b, which is equivalent to adding /B to every pattern. This causes
452        it to show the compiled bytecode, without the additional information that
453        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
454        is the same as /B/I).
456    23. A new optimization is now able automatically to treat some sequences such
457        as a*b as a*+b. More specifically, if something simple (such as a character
458        or a simple class like \d) has an unlimited quantifier, and is followed by
459        something that cannot possibly match the quantified thing, the quantifier
460        is automatically "possessified".
462    24. A recursive reference to a subpattern whose number was greater than 39
463        went wrong under certain circumstances in UTF-8 mode. This bug could also
464        have affected the operation of pcre_study().
466    25. Realized that a little bit of performance could be had by replacing
467        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
469    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
471    27. Possessive quantifiers such as a++ were previously implemented by turning
472        them into atomic groups such as ($>a+). Now they have their own opcodes,
473        which improves performance. This includes the automatically created ones
474        from 23 above.
476    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
477        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
478        the first matched character to be a colon. This applied both to named and
479        numbered groups.
481    29. The ucpinternal.h header file was missing its idempotency #ifdef.
483    30. I was sent a "project" file called libpcre.a.dev which I understand makes
484        building PCRE on Windows easier, so I have included it in the distribution.
486    31. There is now a check in pcretest against a ridiculously large number being
487        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
488        loop, the loop is abandoned.
490    32. Forward references to subpatterns in conditions such as (?(2)...) where
491        subpattern 2 is defined later cause pcre_compile() to search forwards in
492        the pattern for the relevant set of parentheses. This search went wrong
493        when there were unescaped parentheses in a character class, parentheses
494        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
496    33. "Subroutine" calls and backreferences were previously restricted to
497        referencing subpatterns earlier in the regex. This restriction has now
498        been removed.
500    34. Added a number of extra features that are going to be in Perl 5.10. On the
501        whole, these are just syntactic alternatives for features that PCRE had
502        previously implemented using the Python syntax or my own invention. The
503        other formats are all retained for compatibility.
505        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
506            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
507            also .NET compatible.
509        (b) A recursion or subroutine call to a named group can now be defined as
510            (?&name) as well as (?P>name).
512        (c) A backreference to a named group can now be defined as \k<name> or
513            \k'name' as well as (?P=name). The new forms, as well as being in Perl
514            5.10, are also .NET compatible.
516        (d) A conditional reference to a named group can now use the syntax
517            (?(<name>) or (?('name') as well as (?(name).
519        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
520            groups (named and numbered) that are never evaluated inline, but can be
521            called as "subroutines" from elsewhere. In effect, the DEFINE condition
522            is always false. There may be only one alternative in such a group.
524        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
525            as the simple (?(R). The condition is true only if the most recent
526            recursion is that of the given number or name. It does not search out
527            through the entire recursion stack.
529        (g) The escape \gN or \g{N} has been added, where N is a positive or
530            negative number, specifying an absolute or relative reference.
532    35. Tidied to get rid of some further signed/unsigned compiler warnings and
533        some "unreachable code" warnings.
535    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
536        things, this adds five new scripts.
538    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
539        There were also incompatibilities regarding the handling of \Q..\E inside
540        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
541        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
543    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
544        matches an empty string, and forcibly breaks the loop. There were bugs in
545        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
546        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
547        separate and independent bugs (that affected different cases) have been
548        fixed.
550    39. Refactored the code to abolish the use of different opcodes for small
551        capturing bracket numbers. This is a tidy that I avoided doing when I
552        removed the limit on the number of capturing brackets for 3.5 back in 2001.
553        The new approach is not only tidier, it makes it possible to reduce the
554        memory needed to fix the previous bug (38).
556    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
557        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
558        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
559        mode.
561    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
562        report.
564    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
565        copy construction and assignment in the C++ wrapper.
567    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
568        couple of bugs that could have given wrong results in the "--newline=crlf"
569        case.
571    44. Added a number of casts and did some reorganization of signed/unsigned int
572        variables following suggestions from Dair Grant. Also renamed the variable
573        "this" as "item" because it is a C++ keyword.
575    45. Arranged for dftables to add
577          #include "pcre_internal.h"
579        to pcre_chartables.c because without it, gcc 4.x may remove the array
580        definition from the final binary if PCRE is built into a static library and
581        dead code stripping is activated.
583    46. For an unanchored pattern, if a match attempt fails at the start of a
584        newline sequence, and the newline setting is CRLF or ANY, and the next two
585        characters are CRLF, advance by two characters instead of one.
588    Version 6.7 04-Jul-06
589    ---------------------
591     1. In order to handle tests when input lines are enormously long, pcretest has
592        been re-factored so that it automatically extends its buffers when
593        necessary. The code is crude, but this _is_ just a test program. The
594        default size has been increased from 32K to 50K.
596     2. The code in pcre_study() was using the value of the re argument before
597        testing it for NULL. (Of course, in any sensible call of the function, it
598        won't be NULL.)
600     3. The memmove() emulation function in pcre_internal.h, which is used on
601        systems that lack both memmove() and bcopy() - that is, hardly ever -
602        was missing a "static" storage class specifier.
604     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
605        containing an extended class (one that cannot be represented by a bitmap
606        because it contains high-valued characters or Unicode property items, e.g.
607        [\pZ]). Almost always one would set UTF-8 mode when processing such a
608        pattern, but PCRE should not loop if you do not (it no longer does).
609        [Detail: two cases were found: (a) a repeated subpattern containing an
610        extended class; (b) a recursive reference to a subpattern that followed a
611        previous extended class. It wasn't skipping over the extended class
612        correctly when UTF-8 mode was not set.]
614     5. A negated single-character class was not being recognized as fixed-length
615        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
616        compile error "lookbehind assertion is not fixed length".
618     6. The RunPerlTest auxiliary script was showing an unexpected difference
619        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
620        write a Perl script that can interpret lines of an input file either as
621        byte characters or as UTF-8, which is what "perltest" was being required to
622        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
623        can't do is switch easily at run time between having the "use utf8;" pragma
624        or not. In the end, I fudged it by using the RunPerlTest script to insert
625        "use utf8;" explicitly for the UTF-8 tests.
627     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
628        the end of the subject string, contrary to the documentation and to what
629        Perl does. This was true of both matching functions. Now it matches only at
630        the start of the subject and immediately after *internal* newlines.
632     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
633        a pointer to an int instead of a pointer to an unsigned long int. This
634        caused problems on 64-bit systems.
636     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
637        instance of the 'standard' template library not being so standard".
639    10. There was no check on the number of named subpatterns nor the maximum
640        length of a subpattern name. The product of these values is used to compute
641        the size of the memory block for a compiled pattern. By supplying a very
642        long subpattern name and a large number of named subpatterns, the size
643        computation could be caused to overflow. This is now prevented by limiting
644        the length of names to 32 characters, and the number of named subpatterns
645        to 10,000.
647    11. Subpatterns that are repeated with specific counts have to be replicated in
648        the compiled pattern. The size of memory for this was computed from the
649        length of the subpattern and the repeat count. The latter is limited to
650        65535, but there was no limit on the former, meaning that integer overflow
651        could in principle occur. The compiled length of a repeated subpattern is
652        now limited to 30,000 bytes in order to prevent this.
654    12. Added the optional facility to have named substrings with the same name.
656    13. Added the ability to use a named substring as a condition, using the
657        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
658        are numbers (not recommended). Forward references are permitted.
660    14. Added forward references in named backreferences (if you see what I mean).
662    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
663        pattern could run off the end of the subject. For example, the pattern
664        "(?s)(.{1,5})"8 did this with the subject "ab".
666    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
667        PCRE_CASELESS was set when matching characters that were quantified with ?
668        or *.
670    17. A character class other than a single negated character that had a minimum
671        but no maximum quantifier - for example [ab]{6,} - was not handled
672        correctly by pce_dfa_exec(). It would match only one character.
674    18. A valid (though odd) pattern that looked like a POSIX character
675        class but used an invalid character after [ (for example [[,abc,]]) caused
676        pcre_compile() to give the error "Failed: internal error: code overflow" or
677        in some cases to crash with a glibc free() error. This could even happen if
678        the pattern terminated after [[ but there just happened to be a sequence of
679        letters, a binary zero, and a closing ] in the memory that followed.
681    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
682        over the years. Originally (before any Unicode support), just the bottom 8
683        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
684        output from "man perlunicode" includes this:
686          The regular expression compiler produces polymorphic opcodes.  That
687          is, the pattern adapts to the data and automatically switches to
688          the Unicode character scheme when presented with Unicode data--or
689          instead uses a traditional byte scheme when presented with byte
690          data.
692        Sadly, a wide octal escape does not cause a switch, and in a string with
693        no other multibyte characters, these octal escapes are treated as before.
694        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
695        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
696        Unicode string.
698        I have not perpetrated such confusion in PCRE. Up till now, it took just
699        the bottom 8 bits, as in old Perl. I have now made octal escapes with
700        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
701        translate to the appropriate multibyte character.
703    29. Applied some refactoring to reduce the number of warnings from Microsoft
704        and Borland compilers. This has included removing the fudge introduced
705        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
706        a warning about an unused variable.
708    21. PCRE has not included VT (character 0x0b) in the set of whitespace
709        characters since release 4.0, because Perl (from release 5.004) does not.
710        [Or at least, is documented not to: some releases seem to be in conflict
711        with the documentation.] However, when a pattern was studied with
712        pcre_study() and all its branches started with \s, PCRE still included VT
713        as a possible starting character. Of course, this did no harm; it just
714        caused an unnecessary match attempt.
716    22. Removed a now-redundant internal flag bit that recorded the fact that case
717        dependency changed within the pattern. This was once needed for "required
718        byte" processing, but is no longer used. This recovers a now-scarce options
719        bit. Also moved the least significant internal flag bit to the most-
720        significant bit of the word, which was not previously used (hangover from
721        the days when it was an int rather than a uint) to free up another bit for
722        the future.
724    23. Added support for CRLF line endings as well as CR and LF. As well as the
725        default being selectable at build time, it can now be changed at runtime
726        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
727        specify that it is scanning data with non-default line endings.
729    24. Changed the definition of CXXLINK to make it agree with the definition of
730        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
732    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
733        recursions. This makes a big different to stack usage for some patterns.
735    26. If a subpattern containing a named recursion or subroutine reference such
736        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
737        the space required for the compiled pattern went wrong and gave too small a
738        value. Depending on the environment, this could lead to "Failed: internal
739        error: code overflow at offset 49" or "glibc detected double free or
740        corruption" errors.
742    27. Applied patches from Google (a) to support the new newline modes and (b) to
743        advance over multibyte UTF-8 characters in GlobalReplace.
745    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
746        difference for some implementation of PCRE in some Windows version.
748    29. Added some extra testing facilities to pcretest:
750        \q<number>   in a data line sets the "match limit" value
751        \Q<number>   in a data line sets the "match recursion limt" value
752        -S <number>  sets the stack size, where <number> is in megabytes
754        The -S option isn't available for Windows.
757    Version 6.6 06-Feb-06
758    ---------------------
760     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
761        in pcreposix.h. I have copied the definition from pcre.h.
763     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
764        because pcre.h is no longer a built file.
766     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
767        not normally included in the compiled code.
770    Version 6.5 01-Feb-06
771    ---------------------
773     1. When using the partial match feature with pcre_dfa_exec(), it was not
774        anchoring the second and subsequent partial matches at the new starting
775        point. This could lead to incorrect results. For example, with the pattern
776        /1234/, partially matching against "123" and then "a4" gave a match.
778     2. Changes to pcregrep:
780        (a) All non-match returns from pcre_exec() were being treated as failures
781            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
782            error message is output. Some extra information is given for the
783            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
784            probably the only errors that are likely to be caused by users (by
785            specifying a regex that has nested indefinite repeats, for instance).
786            If there are more than 20 of these errors, pcregrep is abandoned.
788        (b) A binary zero was treated as data while matching, but terminated the
789            output line if it was written out. This has been fixed: binary zeroes
790            are now no different to any other data bytes.
792        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
793            used to set a locale for matching. The --locale=xxxx long option has
794            been added (no short equivalent) to specify a locale explicitly on the
795            pcregrep command, overriding the environment variables.
797        (d) When -B was used with -n, some line numbers in the output were one less
798            than they should have been.
800        (e) Added the -o (--only-matching) option.
802        (f) If -A or -C was used with -c (count only), some lines of context were
803            accidentally printed for the final match.
805        (g) Added the -H (--with-filename) option.
807        (h) The combination of options -rh failed to suppress file names for files
808            that were found from directory arguments.
810        (i) Added the -D (--devices) and -d (--directories) options.
812        (j) Added the -F (--fixed-strings) option.
814        (k) Allow "-" to be used as a file name for -f as well as for a data file.
816        (l) Added the --colo(u)r option.
818        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
819            is not present by default.
821     3. A nasty bug was discovered in the handling of recursive patterns, that is,
822        items such as (?R) or (?1), when the recursion could match a number of
823        alternatives. If it matched one of the alternatives, but subsequently,
824        outside the recursion, there was a failure, the code tried to back up into
825        the recursion. However, because of the way PCRE is implemented, this is not
826        possible, and the result was an incorrect result from the match.
828        In order to prevent this happening, the specification of recursion has
829        been changed so that all such subpatterns are automatically treated as
830        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
832     4. I had overlooked the fact that, in some locales, there are characters for
833        which isalpha() is true but neither isupper() nor islower() are true. In
834        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
835        and ordfeminine) are like this. This affected the treatment of \w and \W
836        when they appeared in character classes, but not when they appeared outside
837        a character class. The bit map for "word" characters is now created
838        separately from the results of isalnum() instead of just taking it from the
839        upper, lower, and digit maps. (Plus the underscore character, of course.)
841     5. The above bug also affected the handling of POSIX character classes such as
842        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
843        permanent tables. Instead, the bit maps for such a class were previously
844        created as the appropriate unions of the upper, lower, and digit bitmaps.
845        Now they are created by subtraction from the [[:word:]] class, which has
846        its own bitmap.
848     6. The [[:blank:]] character class matches horizontal, but not vertical space.
849        It is created by subtracting the vertical space characters (\x09, \x0a,
850        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
851        subtraction was done in the overall bitmap for a character class, meaning
852        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
853        be recognized. This bug has been fixed.
855     7. Patches from the folks at Google:
857          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
858          real life, but is still worth protecting against".
860          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
861          regular expressions".
863          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
864          have it.
866          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
867          "configure" and the latter not, in order to fix a problem somebody had
868          with compiling the Arg class on HP-UX.
870          (e) Improve the error-handling of the C++ wrapper a little bit.
872          (f) New tests for checking recursion limiting.
874     8. The pcre_memmove() function, which is used only if the environment does not
875        have a standard memmove() function (and is therefore rarely compiled),
876        contained two bugs: (a) use of int instead of size_t, and (b) it was not
877        returning a result (though PCRE never actually uses the result).
879     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
880        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
881        returned instead of calling malloc() with an overflowing number that would
882        most likely cause subsequent chaos.
884    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
886    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
887        with this option is matched, the nmatch and pmatch options of regexec() are
888        ignored.
890    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
891        provided in case anyone wants to the the POSIX interface with UTF-8
892        strings.
894    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
895        C++ linking (needed for some HP-UX environments).
897    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
898        (unused parameter) and in the pcre_printint() function (omitted "default"
899        switch label when the default is to do nothing).
901    15. Added some code to make it possible, when PCRE is compiled as a C++
902        library, to replace subject pointers for pcre_exec() with a smart pointer
903        class, thus making it possible to process discontinuous strings.
905    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
906        much the same function. They were added by different people who were trying
907        to make PCRE easy to compile on non-Unix systems. It has been suggested
908        that PCRE_EXPORT be abolished now that there is more automatic apparatus
909        for compiling on Windows systems. I have therefore replaced it with
910        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
911        defaults to "extern" for C or "extern C" for C++, which works fine on
912        Unix-like systems. It is now possible to override the value of PCRE_DATA_
913        SCOPE with something explicit in config.h. In addition:
915        (a) pcreposix.h still had just "extern" instead of either of these macros;
916            I have replaced it with PCRE_DATA_SCOPE.
918        (b) Functions such as _pcre_xclass(), which are internal to the library,
919            but external in the C sense, all had PCRE_EXPORT in their definitions.
920            This is apparently wrong for the Windows case, so I have removed it.
921            (It makes no difference on Unix-like systems.)
923    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
924        of recursive calls to match(). This is different to MATCH_LIMIT because
925        that limits the total number of calls to match(), not all of which increase
926        the depth of recursion. Limiting the recursion depth limits the amount of
927        stack (or heap if NO_RECURSE is set) that is used. The default can be set
928        when PCRE is compiled, and changed at run time. A patch from Google adds
929        this functionality to the C++ interface.
931    18. Changes to the handling of Unicode character properties:
933        (a) Updated the table to Unicode 4.1.0.
935        (b) Recognize characters that are not in the table as "Cn" (undefined).
937        (c) I revised the way the table is implemented to a much improved format
938            which includes recognition of ranges. It now supports the ranges that
939            are defined in UnicodeData.txt, and it also amalgamates other
940            characters into ranges. This has reduced the number of entries in the
941            table from around 16,000 to around 3,000, thus reducing its size
942            considerably. I realized I did not need to use a tree structure after
943            all - a binary chop search is just as efficient. Having reduced the
944            number of entries, I extended their size from 6 bytes to 8 bytes to
945            allow for more data.
947        (d) Added support for Unicode script names via properties such as \p{Han}.
949    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
950        matching that character.
952    20. When matching a repeated Unicode property with a minimum greater than zero,
953        (for example \pL{2,}), PCRE could look past the end of the subject if it
954        reached it while seeking the minimum number of characters. This could
955        happen only if some of the characters were more than one byte long, because
956        there is a check for at least the minimum number of bytes.
958    21. Refactored the implementation of \p and \P so as to be more general, to
959        allow for more different types of property in future. This has changed the
960        compiled form incompatibly. Anybody with saved compiled patterns that use
961        \p or \P will have to recompile them.
963    22. Added "Any" and "L&" to the supported property types.
965    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
966        but give a compile time error if the value is greater than 0xff.
968    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
969        accidentally not being installed or uninstalled.
971    25. The pcre.h file was built from pcre.h.in, but the only changes that were
972        made were to insert the current release number. This seemed silly, because
973        it made things harder for people building PCRE on systems that don't run
974        "configure". I have turned pcre.h into a distributed file, no longer built
975        by "configure", with the version identification directly included. There is
976        no longer a pcre.h.in file.
978        However, this change necessitated a change to the pcre-config script as
979        well. It is built from pcre-config.in, and one of the substitutions was the
980        release number. I have updated configure.ac so that ./configure now finds
981        the release number by grepping pcre.h.
983    26. Added the ability to run the tests under valgrind.
986    Version 6.4 05-Sep-05
987    ---------------------
989     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
990        "--" to be printed when multiple files were scanned, even when none of the
991        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
992        consider it to be a bug, and have restored the previous behaviour.
994     2. A couple of code tidies to get rid of compiler warnings.
996     3. The pcretest program used to cheat by referring to symbols in the library
997        whose names begin with _pcre_. These are internal symbols that are not
998        really supposed to be visible externally, and in some environments it is
999        possible to suppress them. The cheating is now confined to including
1000        certain files from the library's source, which is a bit cleaner.
1002     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1003        file's purpose clearer.
1005     5. Reorganized pcre_ucp_findchar().
1008    Version 6.3 15-Aug-05
1009    ---------------------
1011     1. The file libpcre.pc.in did not have general read permission in the tarball.
1013     2. There were some problems when building without C++ support:
1015        (a) If C++ support was not built, "make install" and "make test" still
1016            tried to test it.
1018        (b) There were problems when the value of CXX was explicitly set. Some
1019            changes have been made to try to fix these, and ...
1021        (c) --disable-cpp can now be used to explicitly disable C++ support.
1023        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1024            backslash in a target when C++ was disabled. This confuses some
1025            versions of "make", apparently. Using an intermediate variable solves
1026            this. (Same for CPP_LOBJ.)
1028     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1029        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1030        necessary on certain architectures.
1032     4. Added a setting of -export-symbols-regex to the link command to remove
1033        those symbols that are exported in the C sense, but actually are local
1034        within the library, and not documented. Their names all begin with
1035        "_pcre_". This is not a perfect job, because (a) we have to except some
1036        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1037        available (and never for static libraries). I have made a note to try to
1038        find a way round (a) in the future.
1041    Version 6.2 01-Aug-05
1042    ---------------------
1044     1. There was no test for integer overflow of quantifier values. A construction
1045        such as {1111111111111111} would give undefined results. What is worse, if
1046        a minimum quantifier for a parenthesized subpattern overflowed and became
1047        negative, the calculation of the memory size went wrong. This could have
1048        led to memory overwriting.
1050     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1052     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1053        operating environments where this matters.
1055     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1056        PCRE options from within the C++ wrapper.
1058     5. Named capturing subpatterns were not being correctly counted when a pattern
1059        was compiled. This caused two problems: (a) If there were more than 100
1060        such subpatterns, the calculation of the memory needed for the whole
1061        compiled pattern went wrong, leading to an overflow error. (b) Numerical
1062        back references of the form \12, where the number was greater than 9, were
1063        not recognized as back references, even though there were sufficient
1064        previous subpatterns.
1066     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1067        versions of gcc, e.g. 2.95.4.
1070    Version 6.1 21-Jun-05
1071    ---------------------
1073     1. There was one reference to the variable "posix" in pcretest.c that was not
1074        surrounded by "#if !defined NOPOSIX".
1076     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1077        the cross-check on the old pcre_info() function, for the benefit of the
1078        cut-down version of PCRE that is currently imported into Exim.
1080     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1081        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1082        patterns that start (?i) but I don't think that matters. The use of (?i) is
1083        just an example; this all applies to the other options as well.
1085     4. Since libtool seems to echo the compile commands it is issuing, the output
1086        from "make" can be reduced a bit by putting "@" in front of each libtool
1087        compile command.
1089     5. Patch from the folks at Google for configure.in to be a bit more thorough
1090        in checking for a suitable C++ installation before trying to compile the
1091        C++ stuff. This should fix a reported problem when a compiler was present,
1092        but no suitable headers.
1094     6. The man pages all had just "PCRE" as their title. I have changed them to
1095        be the relevant file name. I have also arranged that these names are
1096        retained in the file doc/pcre.txt, which is a concatenation in text format
1097        of all the man pages except the little individual ones for each function.
1099     7. The NON-UNIX-USE file had not been updated for the different set of source
1100        files that come with release 6. I also added a few comments about the C++
1101        wrapper.
1104    Version 6.0 07-Jun-05
1105    ---------------------
1107     1. Some minor internal re-organization to help with my DFA experiments.
1109     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1110        didn't matter for the library itself when fully configured, but did matter
1111        when compiling without UCP support, or within Exim, where the ucp files are
1112        not imported.
1114     3. Refactoring of the library code to split up the various functions into
1115        different source modules. The addition of the new DFA matching code (see
1116        below) to a single monolithic source would have made it really too
1117        unwieldy, quite apart from causing all the code to be include in a
1118        statically linked application, when only some functions are used. This is
1119        relevant even without the DFA addition now that patterns can be compiled in
1120        one application and matched in another.
1122        The downside of splitting up is that there have to be some external
1123        functions and data tables that are used internally in different modules of
1124        the library but which are not part of the API. These have all had their
1125        names changed to start with "_pcre_" so that they are unlikely to clash
1126        with other external names.
1128     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1129        a different (DFA) algorithm. Although it is slower than the original
1130        function, it does have some advantages for certain types of matching
1131        problem.
1133     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1134        including restarting after a partial match.
1136     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1137        defined when compiling for Windows was sent to me. I have put it into the
1138        code, though I have no means of testing or verifying it.
1140     7. Added the pcre_refcount() auxiliary function.
1142     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1143        match before or at the first newline in the subject string. In pcretest,
1144        the /f option on a pattern can be used to set this.
1146     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1147        would behave wrongly. This has been present in PCRE since release 4.0.
1149    10. A number of changes to the pcregrep command:
1151        (a) Refactored how -x works; insert ^(...)$ instead of setting
1152            PCRE_ANCHORED and checking the length, in preparation for adding
1153            something similar for -w.
1155        (b) Added the -w (match as a word) option.
1157        (c) Refactored the way lines are read and buffered so as to have more
1158            than one at a time available.
1160        (d) Implemented a pcregrep test script.
1162        (e) Added the -M (multiline match) option. This allows patterns to match
1163            over several lines of the subject. The buffering ensures that at least
1164            8K, or the rest of the document (whichever is the shorter) is available
1165            for matching (and similarly the previous 8K for lookbehind assertions).
1167        (f) Changed the --help output so that it now says
1169              -w, --word-regex(p)
1171            instead of two lines, one with "regex" and the other with "regexp"
1172            because that confused at least one person since the short forms are the
1173            same. (This required a bit of code, as the output is generated
1174            automatically from a table. It wasn't just a text change.)
1176        (g) -- can be used to terminate pcregrep options if the next thing isn't an
1177            option but starts with a hyphen. Could be a pattern or a path name
1178            starting with a hyphen, for instance.
1180        (h) "-" can be given as a file name to represent stdin.
1182        (i) When file names are being printed, "(standard input)" is used for
1183            the standard input, for compatibility with GNU grep. Previously
1184            "<stdin>" was used.
1186        (j) The option --label=xxx can be used to supply a name to be used for
1187            stdin when file names are being printed. There is no short form.
1189        (k) Re-factored the options decoding logic because we are going to add
1190            two more options that take data. Such options can now be given in four
1191            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1193        (l) Added the -A, -B, and -C options for requesting that lines of context
1194            around matches be printed.
1196        (m) Added the -L option to print the names of files that do not contain
1197            any matching lines, that is, the complement of -l.
1199        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1200            continue to scan other files.
1202        (o) The -s option was incorrectly implemented. For compatibility with other
1203            greps, it now suppresses the error message for a non-existent or non-
1204            accessible file (but not the return code). There is a new option called
1205            -q that suppresses the output of matching lines, which was what -s was
1206            previously doing.
1208        (p) Added --include and --exclude options to specify files for inclusion
1209            and exclusion when recursing.
1211    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1212        Hopefully, it now does.
1214    12. Missing cast in pcre_study().
1216    13. Added an "uninstall" target to the makefile.
1218    14. Replaced "extern" in the function prototypes in Makefile.in with
1219        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1220        world, but is set differently for Windows.
1222    15. Added a second compiling function called pcre_compile2(). The only
1223        difference is that it has an extra argument, which is a pointer to an
1224        integer error code. When there is a compile-time failure, this is set
1225        non-zero, in addition to the error test pointer being set to point to an
1226        error message. The new argument may be NULL if no error number is required
1227        (but then you may as well call pcre_compile(), which is now just a
1228        wrapper). This facility is provided because some applications need a
1229        numeric error indication, but it has also enabled me to tidy up the way
1230        compile-time errors are handled in the POSIX wrapper.
1232    16. Added VPATH=.libs to the makefile; this should help when building with one
1233        prefix path and installing with another. (Or so I'm told by someone who
1234        knows more about this stuff than I do.)
1236    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1237        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1238        match everything, including newlines. This is not POSIX-compatible, but
1239        somebody wanted the feature. From pcretest it can be activated by using
1240        both the P and the s flags.
1242    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1244    19. libpcre.pc was being incorrectly installed as executable.
1246    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1247        it now also looks for '\r' so that it will work unmodified on Windows.
1249    21. Added Google's contributed C++ wrapper to the distribution.
1251    22. Added some untidy missing memory free() calls in pcretest, to keep
1252        Electric Fence happy when testing.
1256    Version 5.0 13-Sep-04
1257    ---------------------
1259     1. Internal change: literal characters are no longer packed up into items
1260        containing multiple characters in a single byte-string. Each character
1261        is now matched using a separate opcode. However, there may be more than one
1262        byte in the character in UTF-8 mode.
1264     2. The pcre_callout_block structure has two new fields: pattern_position and
1265        next_item_length. These contain the offset in the pattern to the next match
1266        item, and its length, respectively.
1268     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1269        insertion of callouts before each pattern item. Added the /C option to
1270        pcretest to make use of this.
1272     4. On the advice of a Windows user, the lines
1274          #if defined(_WIN32) || defined(WIN32)
1275          _setmode( _fileno( stdout ), 0x8000 );
1276          #endif  /* defined(_WIN32) || defined(WIN32) */
1278        have been added to the source of pcretest. This apparently does useful
1279        magic in relation to line terminators.
1281     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1282        for the benefit of those environments where the "b" makes a difference.
1284     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1285        to know about it. I have put a hack into configure.in that adds in code
1286        to set GCC=yes if CC=icc. This seems to end up at a point in the
1287        generated configure script that is early enough to affect the setting of
1288        compiler options, which is what is needed, but I have no means of testing
1289        whether it really works. (The user who reported this had patched the
1290        generated configure script, which of course I cannot do.)
1292        LATER: After change 22 below (new libtool files), the configure script
1293        seems to know about icc (and also ecc). Therefore, I have commented out
1294        this hack in configure.in.
1296     7. Added support for pkg-config (2 patches were sent in).
1298     8. Negated POSIX character classes that used a combination of internal tables
1299        were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1300        [[:^ascii]]. Typically, they would match almost any characters. The other
1301        POSIX classes were not broken in this way.
1303     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1304        to find the match, as PCRE was deluded into thinking that the match had to
1305        start at the start point or following a newline. The same bug applied to
1306        patterns with negative forward assertions or any backward assertions
1307        preceding ".*" at the start, unless the pattern required a fixed first
1308        character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1310    10. In UTF-8 mode, when moving forwards in the subject after a failed match
1311        starting at the last subject character, bytes beyond the end of the subject
1312        string were read.
1314    11. Renamed the variable "class" as "classbits" to make life easier for C++
1315        users. (Previously there was a macro definition, but it apparently wasn't
1316        enough.)
1318    12. Added the new field "tables" to the extra data so that tables can be passed
1319        in at exec time, or the internal tables can be re-selected. This allows
1320        a compiled regex to be saved and re-used at a later time by a different
1321        program that might have everything at different addresses.
1323    13. Modified the pcre-config script so that, when run on Solaris, it shows a
1324        -R library as well as a -L library.
1326    14. The debugging options of pcretest (-d on the command line or D on a
1327        pattern) showed incorrect output for anything following an extended class
1328        that contained multibyte characters and which was followed by a quantifier.
1330    15. Added optional support for general category Unicode character properties
1331        via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1332        support. It adds about 90K to the size of the library. The meanings of the
1333        inbuilt class escapes such as \d and \s have NOT been changed.
1335    16. Updated pcredemo.c to include calls to free() to release the memory for the
1336        compiled pattern.
1338    17. The generated file chartables.c was being created in the source directory
1339        instead of in the building directory. This caused the build to fail if the
1340        source directory was different from the building directory, and was
1341        read-only.
1343    18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1344        file. No doubt somebody will tell me if they don't make sense... Also added
1345        Dan Mooney's comments about building on OpenVMS.
1347    19. Added support for partial matching via the PCRE_PARTIAL option for
1348        pcre_exec() and the \P data escape in pcretest.
1350    20. Extended pcretest with 3 new pattern features:
1352        (i)   A pattern option of the form ">rest-of-line" causes pcretest to
1353              write the compiled pattern to the file whose name is "rest-of-line".
1354              This is a straight binary dump of the data, with the saved pointer to
1355              the character tables forced to be NULL. The study data, if any, is
1356              written too. After writing, pcretest reads a new pattern.
1358        (ii)  If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1359              compiled pattern from the given file. There must not be any
1360              occurrences of "<" in the file name (pretty unlikely); if there are,
1361              pcretest will instead treat the initial "<" as a pattern delimiter.
1362              After reading in the pattern, pcretest goes on to read data lines as
1363              usual.
1365        (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1366              and 16-bit fields in a compiled pattern, to simulate a pattern that
1367              was compiled on a host of opposite endianness.
1369    21. The pcre-exec() function can now cope with patterns that were compiled on
1370        hosts of opposite endianness, with this restriction:
1372          As for any compiled expression that is saved and used later, the tables
1373          pointer field cannot be preserved; the extra_data field in the arguments
1374          to pcre_exec() should be used to pass in a tables address if a value
1375          other than the default internal tables were used at compile time.
1377    22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1378        now diagnosed as an error. Previously, most of the time, a negative number
1379        would have been treated as zero, but if in addition "ovector" was passed as
1380        NULL, a crash could occur.
1382    23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1383        new versions from the libtool 1.5 distribution (the last one is a copy of
1384        a file called libtool.m4). This seems to have fixed the need to patch
1385        "configure" to support Darwin 1.3 (which I used to do). However, I still
1386        had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1387        workstation).
1389    24. Changed the PCRE licence to be the more standard "BSD" licence.
1392    Version 4.5 01-Dec-03
1393    ---------------------
1395     1. There has been some re-arrangement of the code for the match() function so
1396        that it can be compiled in a version that does not call itself recursively.
1397        Instead, it keeps those local variables that need separate instances for
1398        each "recursion" in a frame on the heap, and gets/frees frames whenever it
1399        needs to "recurse". Keeping track of where control must go is done by means
1400        of setjmp/longjmp. The whole thing is implemented by a set of macros that
1401        hide most of the details from the main code, and operates only if
1402        NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1403        "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1404        operating.
1406        To make it easier for callers to provide specially tailored get/free
1407        functions for this usage, two new functions, pcre_stack_malloc, and
1408        pcre_stack_free, are used. They are always called in strict stacking order,
1409        and the size of block requested is always the same.
1411        The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1412        PCRE has been compiled to use the stack or the heap for recursion. The
1413        -C option of pcretest uses this to show which version is compiled.
1415        A new data escape \S, is added to pcretest; it causes the amounts of store
1416        obtained and freed by both kinds of malloc/free at match time to be added
1417        to the output.
1419     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1420        what's available on my current Linux desktop machine.
1422     3. When matching a UTF-8 string, the test for a valid string at the start has
1423        been extended. If start_offset is not zero, PCRE now checks that it points
1424        to a byte that is the start of a UTF-8 character. If not, it returns
1425        PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1426        this is necessary because there may be backward assertions in the pattern.
1427        When matching the same subject several times, it may save resources to use
1428        PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1430     4. The code for checking the validity of UTF-8 strings has been tightened so
1431        that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1432        containing "overlong sequences".
1434     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1435        I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1436        should have been "&", but it just so happened that all the cases this let
1437        through by mistake were picked up later in the function.
1439     6. I had used a variable called "isblank" - this is a C99 function, causing
1440        some compilers to warn. To avoid this, I renamed it (as "blankclass").
1442     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1443        prompting; (b) run "./pcretest /dev/null" at the start of the test script
1444        so the version is shown; (c) stop "make test" echoing "./RunTest".
1446     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1448     9. The prototype for memmove() for systems that don't have it was using
1449        size_t, but the inclusion of the header that defines size_t was later. I've
1450        moved the #includes for the C headers earlier to avoid this.
1452    10. Added some adjustments to the code to make it easier to compiler on certain
1453        special systems:
1455          (a) Some "const" qualifiers were missing.
1456          (b) Added the macro EXPORT before all exported functions; by default this
1457              is defined to be empty.
1458          (c) Changed the dftables auxiliary program (that builds chartables.c) so
1459              that it reads its output file name as an argument instead of writing
1460              to the standard output and assuming this can be redirected.
1462    11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1463        class containing characters with values greater than 255, PCRE compilation
1464        went into a loop.
1466    12. A recursive reference to a subpattern that was within another subpattern
1467        that had a minimum quantifier of zero caused PCRE to crash. For example,
1468        (x(y(?2))z)? provoked this bug with a subject that got as far as the
1469        recursion. If the recursively-called subpattern itself had a zero repeat,
1470        that was OK.
1472    13. In pcretest, the buffer for reading a data line was set at 30K, but the
1473        buffer into which it was copied (for escape processing) was still set at
1474        1024, so long lines caused crashes.
1476    14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1477        "internal error: code overflow...". This applied to any character class
1478        that was followed by a possessive quantifier.
1480    15. Modified the Makefile to add libpcre.la as a prerequisite for
1481        libpcreposix.la because I was told this is needed for a parallel build to
1482        work.
1484    16. If a pattern that contained .* following optional items at the start was
1485        studied, the wrong optimizing data was generated, leading to matching
1486        errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1487        matching string must start with a or b or c. The correct conclusion for
1488        this pattern is that a match can start with any character.
1491    Version 4.4 13-Aug-03
1492    ---------------------
1494     1. In UTF-8 mode, a character class containing characters with values between
1495        127 and 255 was not handled correctly if the compiled pattern was studied.
1496        In fixing this, I have also improved the studying algorithm for such
1497        classes (slightly).
1499     2. Three internal functions had redundant arguments passed to them. Removal
1500        might give a very teeny performance improvement.
1502     3. Documentation bug: the value of the capture_top field in a callout is *one
1503        more than* the number of the hightest numbered captured substring.
1505     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1506        in incorrectly linking with a previously installed version. They now link
1507        explicitly with libpcre.la.
1509     5. configure.in no longer needs to recognize Cygwin specially.
1511     6. A problem in pcre.in for Windows platforms is fixed.
1513     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1514        pcretest, it used to include the size of the study block as part of its
1515        output. Unfortunately, the structure contains a field that has a different
1516        size on different hardware architectures. This meant that the tests that
1517        showed this size failed. As the block is currently always of a fixed size,
1518        this information isn't actually particularly useful in pcretest output, so
1519        I have just removed it.
1521     8. Three pre-processor statements accidentally did not start in column 1.
1522        Sadly, there are *still* compilers around that complain, even though
1523        standard C has not required this for well over a decade. Sigh.
1525     9. In pcretest, the code for checking callouts passed small integers in the
1526        callout_data field, which is a void * field. However, some picky compilers
1527        complained about the casts involved for this on 64-bit systems. Now
1528        pcretest passes the address of the small integer instead, which should get
1529        rid of the warnings.
1531    10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1532        both compile and run time, and gives an error if an invalid UTF-8 sequence
1533        is found. There is a option for disabling this check in cases where the
1534        string is known to be correct and/or the maximum performance is wanted.
1536    11. In response to a bug report, I changed one line in Makefile.in from
1538            -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1539        to
1540            -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1542        to look similar to other lines, but I have no way of telling whether this
1543        is the right thing to do, as I do not use Windows. No doubt I'll get told
1544        if it's wrong...
1547  Version 4.3 21-May-03  Version 4.3 21-May-03
1548  ---------------------  ---------------------

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