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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.4 21-Sep-07
5    ---------------------
7    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
8        means that a class such as [\s] counted as "explicit reference to CR or
9        LF". That isn't really right - the whole point of the change was to try to
10        help when there was an actual mention of one of the two characters. So now
11        the change happens only if \r or \n (or a literal CR or LF) character is
12        encountered.
14    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
15        of both had grown to the point where there were only 3 bits left.
16        Fortunately, there was spare space in the data structure, and so I have
17        moved the internal flags into a new 16-bit field to free up more option
18        bits.
20    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
21        but did not set the internal JCHANGED flag - either of these is enough to
22        control the way the "get" function works - but the PCRE_INFO_JCHANGED
23        facility is supposed to tell if (?J) was ever used, so now (?J) at the
24        start sets both bits.
26    4.  Added options (at build time, compile time, exec time) to change \R from
27        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
29    5.  doc/pcresyntax.html was missing from the distribution.
31    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
32        compatibility, even though it is no longer used.
34    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
35        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
36        windows.h file is present (where different names are used). [This was
37        reversed later after testing - see 16 below.]
39    8.  Changed all #include <config.h> to #include "config.h". There were also
40        some further <pcre.h> cases that I changed to "pcre.h".
42    9.  When pcregrep was used with the --colour option, it missed the line ending
43        sequence off the lines that it output.
45    10. It was pointed out to me that arrays of string pointers cause lots of
46        relocations when a shared library is dynamically loaded. A technique of
47        using a single long string with a table of offsets can drastically reduce
48        these. I have refactored PCRE in four places to do this. The result is
49        dramatic:
51          Originally:                          290
52          After changing UCP table:            187
53          After changing error message table:   43
54          After changing table of "verbs"       36
55          After changing table of Posix names   22
57        Thanks to the folks working on Gregex for glib for this insight.
59    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
60        unicode-properties was also set.
62    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
64    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
65        checked only for CRLF.
67    14. Added casts to pcretest.c to avoid compiler warnings.
69    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
71    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
72        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
73        entirely. This removes changes made in 7 above.
75    17. The CMake files have been updated, and there is now more information about
76        building with CMake in the NON-UNIX-USE document.
79    Version 7.3 28-Aug-07
80    ---------------------
82     1. In the rejigging of the build system that eventually resulted in 7.1, the
83        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
84        brackets there is not right, since it causes compilers to look for an
85        installed pcre.h, not the version that is in the source that is being
86        compiled (which of course may be different). I have changed it back to:
88          #include "pcre.h"
90        I have a vague recollection that the change was concerned with compiling in
91        different directories, but in the new build system, that is taken care of
92        by the VPATH setting the Makefile.
94     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
95        when the subject happened to end in the byte 0x85 (e.g. if the last
96        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
97        characters but of course it shouldn't be taken as a newline when it is part
98        of another character. The bug was that, for an unlimited repeat of . in
99        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
100        characters when looking for a newline.
102     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
104     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
105        in debug output.
107     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
108        long printing in the pcrecpp unittest when running under MinGW.
110     6. ESC_K was left out of the EBCDIC table.
112     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
113        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
114        limit also applies to "virtual nesting" when a pattern is recursive, and in
115        this case 1000 isn't so big. I have been able to remove this limit at the
116        expense of backing off one optimization in certain circumstances. Normally,
117        when pcre_exec() would call its internal match() function recursively and
118        immediately return the result unconditionally, it uses a "tail recursion"
119        feature to save stack. However, when a subpattern that can match an empty
120        string has an unlimited repetition quantifier, it no longer makes this
121        optimization. That gives it a stack frame in which to save the data for
122        checking that an empty string has been matched. Previously this was taken
123        from the 1000-entry workspace that had been reserved. So now there is no
124        explicit limit, but more stack is used.
126     8. Applied Daniel's patches to solve problems with the import/export magic
127        syntax that is required for Windows, and which was going wrong for the
128        pcreposix and pcrecpp parts of the library. These were overlooked when this
129        problem was solved for the main library.
131     9. There were some crude static tests to avoid integer overflow when computing
132        the size of patterns that contain repeated groups with explicit upper
133        limits. As the maximum quantifier is 65535, the maximum group length was
134        set at 30,000 so that the product of these two numbers did not overflow a
135        32-bit integer. However, it turns out that people want to use groups that
136        are longer than 30,000 bytes (though not repeat them that many times).
137        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
138        made it possible to implement the integer overflow checks in a much more
139        dynamic way, which I have now done. The artificial limitation on group
140        length has been removed - we now have only the limit on the total length of
141        the compiled pattern, which depends on the LINK_SIZE setting.
143    10. Fixed a bug in the documentation for get/copy named substring when
144        duplicate names are permitted. If none of the named substrings are set, the
145        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
146        empty string.
148    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
149        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
150        because the ] is interpreted as the first data character and the
151        terminating ] is not found. PCRE has been made compatible with Perl in this
152        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
153        cause memory overwriting.
155    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
156        string has been matched (to stop an infinite loop). It was not recognizing
157        a conditional subpattern that could match an empty string if that
158        subpattern was within another subpattern. For example, it looped when
159        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
160        condition was not nested. This bug has been fixed.
162    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
163        past the start of the subject in the presence of bytes with the top bit
164        set, for example "\x8aBCD".
166    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
167        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
169    14. Optimized (?!) to (*FAIL).
171    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
172        This restricts code points to be within the range 0 to 0x10FFFF, excluding
173        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
174        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
175        does: it's just the validity check that is more restrictive.
177    16. Inserted checks for integer overflows during escape sequence (backslash)
178        processing, and also fixed erroneous offset values for syntax errors during
179        backslash processing.
181    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
182        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
184    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
185        caused an overrun.
187    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
188        something other than just ASCII characters) inside a group that had an
189        unlimited repeat caused a loop at compile time (while checking to see
190        whether the group could match an empty string).
192    20. Debugging a pattern containing \p or \P could cause a crash. For example,
193        [\P{Any}] did so. (Error in the code for printing property names.)
195    21. An orphan \E inside a character class could cause a crash.
197    22. A repeated capturing bracket such as (A)? could cause a wild memory
198        reference during compilation.
200    23. There are several functions in pcre_compile() that scan along a compiled
201        expression for various reasons (e.g. to see if it's fixed length for look
202        behind). There were bugs in these functions when a repeated \p or \P was
203        present in the pattern. These operators have additional parameters compared
204        with \d, etc, and these were not being taken into account when moving along
205        the compiled data. Specifically:
207        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
208            length.
210        (b) An item such as \pL+ within a repeated group could cause crashes or
211            loops.
213        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
214            "reference to non-existent subpattern" error.
216        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
218    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
219        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
221    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
223    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
224        character were causing crashes (broken optimization).
226    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
227        \p or \P) caused a compile-time loop.
229    28. More problems have arisen in unanchored patterns when CRLF is a valid line
230        break. For example, the unstudied pattern [\r\n]A does not match the string
231        "\r\nA" because change 7.0/46 below moves the current point on by two
232        characters after failing to match at the start. However, the pattern \nA
233        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
234        the same is true. There doesn't seem any very clean way out of this, but
235        what I have chosen to do makes the common cases work: PCRE now takes note
236        of whether there can be an explicit match for \r or \n anywhere in the
237        pattern, and if so, 7.0/46 no longer applies. As part of this change,
238        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
239        pattern has explicit CR or LF references.
241    29. Added (*CR) etc for changing newline setting at start of pattern.
244    Version 7.2 19-Jun-07
245    ---------------------
247     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
248        which is apparently normally available under Windows.
250     2. Re-jig the pcregrep tests with different newline settings in an attempt
251        to make them independent of the local environment's newline setting.
253     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
255     4. Some of the "internals" tests were previously cut out when the link size
256        was not 2, because the output contained actual offsets. The recent new
257        "Z" feature of pcretest means that these can be cut out, making the tests
258        usable with all link sizes.
260     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
261        stack recursion. This gives a massive performance boost under BSD, but just
262        a small improvement under Linux. However, it saves one field in the frame
263        in all cases.
265     6. Added more features from the forthcoming Perl 5.10:
267        (a) (?-n) (where n is a string of digits) is a relative subroutine or
268            recursion call. It refers to the nth most recently opened parentheses.
270        (b) (?+n) is also a relative subroutine call; it refers to the nth next
271            to be opened parentheses.
273        (c) Conditions that refer to capturing parentheses can be specified
274            relatively, for example, (?(-2)... or (?(+3)...
276        (d) \K resets the start of the current match so that everything before
277            is not part of it.
279        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
281        (f) \g{name} is another synonym - part of Perl 5.10's unification of
282            reference syntax.
284        (g) (?| introduces a group in which the numbering of parentheses in each
285            alternative starts with the same number.
287        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
289     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
292     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
293        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
294        for detecting groups that can match an empty string.
296     9. A pattern with a very large number of alternatives (more than several
297        hundred) was running out of internal workspace during the pre-compile
298        phase, where pcre_compile() figures out how much memory will be needed. A
299        bit of new cunning has reduced the workspace needed for groups with
300        alternatives. The 1000-alternative test pattern now uses 12 bytes of
301        workspace instead of running out of the 4096 that are available.
303    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
305    11. Applied patch from Google to remove an optimization that didn't quite work.
306        The report of the bug said:
308          pcrecpp::RE("a*").FullMatch("aaa") matches, while
309          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
310          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
312    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
313        it matched the wrong number of bytes.
316    Version 7.1 24-Apr-07
317    ---------------------
319     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
320        that is more "standard", making use of automake and other Autotools. There
321        is some re-arrangement of the files and adjustment of comments consequent
322        on this.
324     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
325        for recursive directory scanning broke on some systems because the files
326        are not scanned in any specific order and on different systems the order
327        was different. A call to "sort" has been inserted into RunGrepTest for the
328        approprate test as a short-term fix. In the longer term there may be an
329        alternative.
331     3. I had an email from Eric Raymond about problems translating some of PCRE's
332        man pages to HTML (despite the fact that I distribute HTML pages, some
333        people do their own conversions for various reasons). The problems
334        concerned the use of low-level troff macros .br and .in. I have therefore
335        removed all such uses from the man pages (some were redundant, some could
336        be replaced by .nf/.fi pairs). The 132html script that I use to generate
337        HTML has been updated to handle .nf/.fi and to complain if it encounters
338        .br or .in.
340     4. Updated comments in configure.ac that get placed in config.h.in and also
341        arranged for config.h to be included in the distribution, with the name
342        config.h.generic, for the benefit of those who have to compile without
343        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
345     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
346        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
347        makevp.bat for the current PCRE, using the additional files
348        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
350     6. A Windows user reported a minor discrepancy with test 2, which turned out
351        to be caused by a trailing space on an input line that had got lost in his
352        copy. The trailing space was an accident, so I've just removed it.
354     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
355        that is needed.
357     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
358        as "const" (a) because they are and (b) because it helps the PHP
359        maintainers who have recently made a script to detect big data structures
360        in the php code that should be moved to the .rodata section. I remembered
361        to update Builducptable as well, so it won't revert if ucptable.h is ever
362        re-created.
364     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
365        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
366        order to be able to cut out the UTF-8 tables in the latter when UTF-8
367        support is not required. This saves 1.5-2K of code, which is important in
368        some applications.
370        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
371        so as not to refer to the tables, even though these functions will never be
372        called when UTF-8 support is disabled. Otherwise there are problems with a
373        shared library.
375    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
377        (a) It was defining its arguments as char * instead of void *.
379        (b) It was assuming that all moves were upwards in memory; this was true
380            a long time ago when I wrote it, but is no longer the case.
382        The emulated memove() is provided for those environments that have neither
383        memmove() nor bcopy(). I didn't think anyone used it these days, but that
384        is clearly not the case, as these two bugs were recently reported.
386    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
387        and Detrail to create the HTML documentation, the .txt form of the man
388        pages, and it removes trailing spaces from listed files. It also creates
389        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
390        case, it wraps all the #defines with #ifndefs. This script should be run
391        before "make dist".
393    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
394        with Unicode property support.
396        (a) For a maximizing quantifier, if the two different cases of the
397            character were of different lengths in their UTF-8 codings (there are
398            some cases like this - I found 11), and the matching function had to
399            back up over a mixture of the two cases, it incorrectly assumed they
400            were both the same length.
402        (b) When PCRE was configured to use the heap rather than the stack for
403            recursion during matching, it was not correctly preserving the data for
404            the other case of a UTF-8 character when checking ahead for a match
405            while processing a minimizing repeat. If the check also involved
406            matching a wide character, but failed, corruption could cause an
407            erroneous result when trying to check for a repeat of the original
408            character.
410    13. Some tidying changes to the testing mechanism:
412        (a) The RunTest script now detects the internal link size and whether there
413            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
414            values substituted by "configure". (The RunGrepTest script already did
415            this for UTF-8.) The configure.ac script no longer substitutes the
416            relevant variables.
418        (b) The debugging options /B and /D in pcretest show the compiled bytecode
419            with length and offset values. This means that the output is different
420            for different internal link sizes. Test 2 is skipped for link sizes
421            other than 2 because of this, bypassing the problem. Unfortunately,
422            there was also a test in test 3 (the locale tests) that used /B and
423            failed for link sizes other than 2. Rather than cut the whole test out,
424            I have added a new /Z option to pcretest that replaces the length and
425            offset values with spaces. This is now used to make test 3 independent
426            of link size. (Test 2 will be tidied up later.)
428    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
429        segmentation fault instead of returning the appropriate error message.
431    15. In multiline mode when the newline sequence was set to "any", the pattern
432        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
433        This doesn't seem right; it now treats the CRLF combination as the line
434        ending, and so does not match in that case. It's only a pattern such as ^$
435        that would hit this one: something like ^ABC$ would have failed after \r
436        and then tried again after \r\n.
438    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
439        in an attempt to make files that differ only in their line terminators
440        compare equal. This works on Linux.
442    17. Under certain error circumstances pcregrep might try to free random memory
443        as it exited. This is now fixed, thanks to valgrind.
445    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
446        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
447        was because its rules for how to advance for /g after matching an empty
448        string at the end of a line did not allow for this case. They now check for
449        it specially.
451    20. pcretest is supposed to handle patterns and data of any length, by
452        extending its buffers when necessary. It was getting this wrong when the
453        buffer for a data line had to be extended.
455    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
456        CRLF as a newline sequence.
458    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
459        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
460        I have nevertheless tidied it up.
462    23. Added some casts to kill warnings from HP-UX ia64 compiler.
464    24. Added a man page for pcre-config.
467    Version 7.0 19-Dec-06
468    ---------------------
470     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
471        moving to gcc 4.1.1.
473     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
474        sys/time.h, which is documented as needed for this function. It doesn't
475        seem to matter on Linux, but it showed up on some releases of OS X.
477     3. It seems that there are systems where bytes whose values are greater than
478        127 match isprint() in the "C" locale. The "C" locale should be the
479        default when a C program starts up. In most systems, only ASCII printing
480        characters match isprint(). This difference caused the output from pcretest
481        to vary, making some of the tests fail. I have changed pcretest so that:
483        (a) When it is outputting text in the compiled version of a pattern, bytes
484            other than 32-126 are always shown as hex escapes.
486        (b) When it is outputting text that is a matched part of a subject string,
487            it does the same, unless a different locale has been set for the match
488            (using the /L modifier). In this case, it uses isprint() to decide.
490     4. Fixed a major bug that caused incorrect computation of the amount of memory
491        required for a compiled pattern when options that changed within the
492        pattern affected the logic of the preliminary scan that determines the
493        length. The relevant options are -x, and -i in UTF-8 mode. The result was
494        that the computed length was too small. The symptoms of this bug were
495        either the PCRE error "internal error: code overflow" from pcre_compile(),
496        or a glibc crash with a message such as "pcretest: free(): invalid next
497        size (fast)". Examples of patterns that provoked this bug (shown in
498        pcretest format) are:
500          /(?-x: )/x
501          /(?x)(?-x: \s*#\s*)/
502          /((?i)[\x{c0}])/8
503          /(?i:[\x{c0}])/8
505        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
506        is now done differently.
508     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
509        wrapper classes; (b) implement a new function in the C++ scanner that is
510        more efficient than the old way of doing things because it avoids levels of
511        recursion in the regex matching; (c) add a paragraph to the documentation
512        for the FullMatch() function.
514     6. The escape sequence \n was being treated as whatever was defined as
515        "newline". Not only was this contrary to the documentation, which states
516        that \n is character 10 (hex 0A), but it also went horribly wrong when
517        "newline" was defined as CRLF. This has been fixed.
519     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
520        was being set to -1 for the "end of line" case (supposedly a value that no
521        character can have). Though this value is never used (the check for end of
522        line is "zero bytes in current character"), it caused compiler complaints.
523        I've changed it to 0xffffffff.
525     8. In pcre_version.c, the version string was being built by a sequence of
526        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
527        string (as it is for production releases) called a macro with an empty
528        argument. The C standard says the result of this is undefined. The gcc
529        compiler treats it as an empty string (which was what was wanted) but it is
530        reported that Visual C gives an error. The source has been hacked around to
531        avoid this problem.
533     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
534        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
535        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
536        of them did).
538    10. Originally, pcretest opened its input and output without "b"; then I was
539        told that "b" was needed in some environments, so it was added for release
540        5.0 to both the input and output. (It makes no difference on Unix-like
541        systems.) Later I was told that it is wrong for the input on Windows. I've
542        now abstracted the modes into two macros, to make it easier to fiddle with
543        them, and removed "b" from the input mode under Windows.
545    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
547    12. Added -help and --help to pcretest as an official way of being reminded
548        of the options.
550    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
551        and pcrecpp.cc because they annoy compilers at high warning levels.
553    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
555    15. Fixed an occurrence of == in configure.ac that should have been = (shell
556        scripts are not C programs :-) and which was not noticed because it works
557        on Linux.
559    16. pcretest is supposed to handle any length of pattern and data line (as one
560        line or as a continued sequence of lines) by extending its input buffer if
561        necessary. This feature was broken for very long pattern lines, leading to
562        a string of junk being passed to pcre_compile() if the pattern was longer
563        than about 50K.
565    17. I have done a major re-factoring of the way pcre_compile() computes the
566        amount of memory needed for a compiled pattern. Previously, there was code
567        that made a preliminary scan of the pattern in order to do this. That was
568        OK when PCRE was new, but as the facilities have expanded, it has become
569        harder and harder to keep it in step with the real compile phase, and there
570        have been a number of bugs (see for example, 4 above). I have now found a
571        cunning way of running the real compile function in a "fake" mode that
572        enables it to compute how much memory it would need, while actually only
573        ever using a few hundred bytes of working memory and without too many
574        tests of the mode. This should make future maintenance and development
575        easier. A side effect of this work is that the limit of 200 on the nesting
576        depth of parentheses has been removed (though this was never a serious
577        limitation, I suspect). However, there is a downside: pcre_compile() now
578        runs more slowly than before (30% or more, depending on the pattern). I
579        hope this isn't a big issue. There is no effect on runtime performance.
581    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
582        newline (only possible for the last line of a file) and it was a
583        pattern that set a locale (followed by /Lsomething), pcretest crashed.
585    19. Added additional timing features to pcretest. (1) The -tm option now times
586        matching only, not compiling. (2) Both -t and -tm can be followed, as a
587        separate command line item, by a number that specifies the number of
588        repeats to use when timing. The default is 50000; this gives better
589        precision, but takes uncomfortably long for very large patterns.
591    20. Extended pcre_study() to be more clever in cases where a branch of a
592        subpattern has no definite first character. For example, (a*|b*)[cd] would
593        previously give no result from pcre_study(). Now it recognizes that the
594        first character must be a, b, c, or d.
596    21. There was an incorrect error "recursive call could loop indefinitely" if
597        a subpattern (or the entire pattern) that was being tested for matching an
598        empty string contained only one non-empty item after a nested subpattern.
599        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
600        incorrectly, because the \d was being skipped in the check.
602    22. The pcretest program now has a new pattern option /B and a command line
603        option -b, which is equivalent to adding /B to every pattern. This causes
604        it to show the compiled bytecode, without the additional information that
605        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
606        is the same as /B/I).
608    23. A new optimization is now able automatically to treat some sequences such
609        as a*b as a*+b. More specifically, if something simple (such as a character
610        or a simple class like \d) has an unlimited quantifier, and is followed by
611        something that cannot possibly match the quantified thing, the quantifier
612        is automatically "possessified".
614    24. A recursive reference to a subpattern whose number was greater than 39
615        went wrong under certain circumstances in UTF-8 mode. This bug could also
616        have affected the operation of pcre_study().
618    25. Realized that a little bit of performance could be had by replacing
619        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
621    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
623    27. Possessive quantifiers such as a++ were previously implemented by turning
624        them into atomic groups such as ($>a+). Now they have their own opcodes,
625        which improves performance. This includes the automatically created ones
626        from 23 above.
628    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
629        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
630        the first matched character to be a colon. This applied both to named and
631        numbered groups.
633    29. The ucpinternal.h header file was missing its idempotency #ifdef.
635    30. I was sent a "project" file called libpcre.a.dev which I understand makes
636        building PCRE on Windows easier, so I have included it in the distribution.
638    31. There is now a check in pcretest against a ridiculously large number being
639        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
640        loop, the loop is abandoned.
642    32. Forward references to subpatterns in conditions such as (?(2)...) where
643        subpattern 2 is defined later cause pcre_compile() to search forwards in
644        the pattern for the relevant set of parentheses. This search went wrong
645        when there were unescaped parentheses in a character class, parentheses
646        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
648    33. "Subroutine" calls and backreferences were previously restricted to
649        referencing subpatterns earlier in the regex. This restriction has now
650        been removed.
652    34. Added a number of extra features that are going to be in Perl 5.10. On the
653        whole, these are just syntactic alternatives for features that PCRE had
654        previously implemented using the Python syntax or my own invention. The
655        other formats are all retained for compatibility.
657        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
658            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
659            also .NET compatible.
661        (b) A recursion or subroutine call to a named group can now be defined as
662            (?&name) as well as (?P>name).
664        (c) A backreference to a named group can now be defined as \k<name> or
665            \k'name' as well as (?P=name). The new forms, as well as being in Perl
666            5.10, are also .NET compatible.
668        (d) A conditional reference to a named group can now use the syntax
669            (?(<name>) or (?('name') as well as (?(name).
671        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
672            groups (named and numbered) that are never evaluated inline, but can be
673            called as "subroutines" from elsewhere. In effect, the DEFINE condition
674            is always false. There may be only one alternative in such a group.
676        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
677            as the simple (?(R). The condition is true only if the most recent
678            recursion is that of the given number or name. It does not search out
679            through the entire recursion stack.
681        (g) The escape \gN or \g{N} has been added, where N is a positive or
682            negative number, specifying an absolute or relative reference.
684    35. Tidied to get rid of some further signed/unsigned compiler warnings and
685        some "unreachable code" warnings.
687    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
688        things, this adds five new scripts.
690    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
691        There were also incompatibilities regarding the handling of \Q..\E inside
692        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
693        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
695    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
696        matches an empty string, and forcibly breaks the loop. There were bugs in
697        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
698        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
699        separate and independent bugs (that affected different cases) have been
700        fixed.
702    39. Refactored the code to abolish the use of different opcodes for small
703        capturing bracket numbers. This is a tidy that I avoided doing when I
704        removed the limit on the number of capturing brackets for 3.5 back in 2001.
705        The new approach is not only tidier, it makes it possible to reduce the
706        memory needed to fix the previous bug (38).
708    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
709        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
710        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
711        mode.
713    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
714        report.
716    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
717        copy construction and assignment in the C++ wrapper.
719    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
720        couple of bugs that could have given wrong results in the "--newline=crlf"
721        case.
723    44. Added a number of casts and did some reorganization of signed/unsigned int
724        variables following suggestions from Dair Grant. Also renamed the variable
725        "this" as "item" because it is a C++ keyword.
727    45. Arranged for dftables to add
729          #include "pcre_internal.h"
731        to pcre_chartables.c because without it, gcc 4.x may remove the array
732        definition from the final binary if PCRE is built into a static library and
733        dead code stripping is activated.
735    46. For an unanchored pattern, if a match attempt fails at the start of a
736        newline sequence, and the newline setting is CRLF or ANY, and the next two
737        characters are CRLF, advance by two characters instead of one.
740    Version 6.7 04-Jul-06
741    ---------------------
743     1. In order to handle tests when input lines are enormously long, pcretest has
744        been re-factored so that it automatically extends its buffers when
745        necessary. The code is crude, but this _is_ just a test program. The
746        default size has been increased from 32K to 50K.
748     2. The code in pcre_study() was using the value of the re argument before
749        testing it for NULL. (Of course, in any sensible call of the function, it
750        won't be NULL.)
752     3. The memmove() emulation function in pcre_internal.h, which is used on
753        systems that lack both memmove() and bcopy() - that is, hardly ever -
754        was missing a "static" storage class specifier.
756     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
757        containing an extended class (one that cannot be represented by a bitmap
758        because it contains high-valued characters or Unicode property items, e.g.
759        [\pZ]). Almost always one would set UTF-8 mode when processing such a
760        pattern, but PCRE should not loop if you do not (it no longer does).
761        [Detail: two cases were found: (a) a repeated subpattern containing an
762        extended class; (b) a recursive reference to a subpattern that followed a
763        previous extended class. It wasn't skipping over the extended class
764        correctly when UTF-8 mode was not set.]
766     5. A negated single-character class was not being recognized as fixed-length
767        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
768        compile error "lookbehind assertion is not fixed length".
770     6. The RunPerlTest auxiliary script was showing an unexpected difference
771        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
772        write a Perl script that can interpret lines of an input file either as
773        byte characters or as UTF-8, which is what "perltest" was being required to
774        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
775        can't do is switch easily at run time between having the "use utf8;" pragma
776        or not. In the end, I fudged it by using the RunPerlTest script to insert
777        "use utf8;" explicitly for the UTF-8 tests.
779     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
780        the end of the subject string, contrary to the documentation and to what
781        Perl does. This was true of both matching functions. Now it matches only at
782        the start of the subject and immediately after *internal* newlines.
784     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
785        a pointer to an int instead of a pointer to an unsigned long int. This
786        caused problems on 64-bit systems.
788     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
789        instance of the 'standard' template library not being so standard".
791    10. There was no check on the number of named subpatterns nor the maximum
792        length of a subpattern name. The product of these values is used to compute
793        the size of the memory block for a compiled pattern. By supplying a very
794        long subpattern name and a large number of named subpatterns, the size
795        computation could be caused to overflow. This is now prevented by limiting
796        the length of names to 32 characters, and the number of named subpatterns
797        to 10,000.
799    11. Subpatterns that are repeated with specific counts have to be replicated in
800        the compiled pattern. The size of memory for this was computed from the
801        length of the subpattern and the repeat count. The latter is limited to
802        65535, but there was no limit on the former, meaning that integer overflow
803        could in principle occur. The compiled length of a repeated subpattern is
804        now limited to 30,000 bytes in order to prevent this.
806    12. Added the optional facility to have named substrings with the same name.
808    13. Added the ability to use a named substring as a condition, using the
809        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
810        are numbers (not recommended). Forward references are permitted.
812    14. Added forward references in named backreferences (if you see what I mean).
814    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
815        pattern could run off the end of the subject. For example, the pattern
816        "(?s)(.{1,5})"8 did this with the subject "ab".
818    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
819        PCRE_CASELESS was set when matching characters that were quantified with ?
820        or *.
822    17. A character class other than a single negated character that had a minimum
823        but no maximum quantifier - for example [ab]{6,} - was not handled
824        correctly by pce_dfa_exec(). It would match only one character.
826    18. A valid (though odd) pattern that looked like a POSIX character
827        class but used an invalid character after [ (for example [[,abc,]]) caused
828        pcre_compile() to give the error "Failed: internal error: code overflow" or
829        in some cases to crash with a glibc free() error. This could even happen if
830        the pattern terminated after [[ but there just happened to be a sequence of
831        letters, a binary zero, and a closing ] in the memory that followed.
833    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
834        over the years. Originally (before any Unicode support), just the bottom 8
835        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
836        output from "man perlunicode" includes this:
838          The regular expression compiler produces polymorphic opcodes.  That
839          is, the pattern adapts to the data and automatically switches to
840          the Unicode character scheme when presented with Unicode data--or
841          instead uses a traditional byte scheme when presented with byte
842          data.
844        Sadly, a wide octal escape does not cause a switch, and in a string with
845        no other multibyte characters, these octal escapes are treated as before.
846        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
847        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
848        Unicode string.
850        I have not perpetrated such confusion in PCRE. Up till now, it took just
851        the bottom 8 bits, as in old Perl. I have now made octal escapes with
852        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
853        translate to the appropriate multibyte character.
855    29. Applied some refactoring to reduce the number of warnings from Microsoft
856        and Borland compilers. This has included removing the fudge introduced
857        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
858        a warning about an unused variable.
860    21. PCRE has not included VT (character 0x0b) in the set of whitespace
861        characters since release 4.0, because Perl (from release 5.004) does not.
862        [Or at least, is documented not to: some releases seem to be in conflict
863        with the documentation.] However, when a pattern was studied with
864        pcre_study() and all its branches started with \s, PCRE still included VT
865        as a possible starting character. Of course, this did no harm; it just
866        caused an unnecessary match attempt.
868    22. Removed a now-redundant internal flag bit that recorded the fact that case
869        dependency changed within the pattern. This was once needed for "required
870        byte" processing, but is no longer used. This recovers a now-scarce options
871        bit. Also moved the least significant internal flag bit to the most-
872        significant bit of the word, which was not previously used (hangover from
873        the days when it was an int rather than a uint) to free up another bit for
874        the future.
876    23. Added support for CRLF line endings as well as CR and LF. As well as the
877        default being selectable at build time, it can now be changed at runtime
878        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
879        specify that it is scanning data with non-default line endings.
881    24. Changed the definition of CXXLINK to make it agree with the definition of
882        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
884    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
885        recursions. This makes a big different to stack usage for some patterns.
887    26. If a subpattern containing a named recursion or subroutine reference such
888        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
889        the space required for the compiled pattern went wrong and gave too small a
890        value. Depending on the environment, this could lead to "Failed: internal
891        error: code overflow at offset 49" or "glibc detected double free or
892        corruption" errors.
894    27. Applied patches from Google (a) to support the new newline modes and (b) to
895        advance over multibyte UTF-8 characters in GlobalReplace.
897    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
898        difference for some implementation of PCRE in some Windows version.
900    29. Added some extra testing facilities to pcretest:
902        \q<number>   in a data line sets the "match limit" value
903        \Q<number>   in a data line sets the "match recursion limt" value
904        -S <number>  sets the stack size, where <number> is in megabytes
906        The -S option isn't available for Windows.
909    Version 6.6 06-Feb-06
910    ---------------------
912     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
913        in pcreposix.h. I have copied the definition from pcre.h.
915     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
916        because pcre.h is no longer a built file.
918     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
919        not normally included in the compiled code.
922  Version 6.5 01-Feb-06  Version 6.5 01-Feb-06
923  ---------------------  ---------------------

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