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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.
76    Version 7.3 28-Aug-07
77    ---------------------
79     1. In the rejigging of the build system that eventually resulted in 7.1, the
80        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
81        brackets there is not right, since it causes compilers to look for an
82        installed pcre.h, not the version that is in the source that is being
83        compiled (which of course may be different). I have changed it back to:
85          #include "pcre.h"
87        I have a vague recollection that the change was concerned with compiling in
88        different directories, but in the new build system, that is taken care of
89        by the VPATH setting the Makefile.
91     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
92        when the subject happened to end in the byte 0x85 (e.g. if the last
93        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
94        characters but of course it shouldn't be taken as a newline when it is part
95        of another character. The bug was that, for an unlimited repeat of . in
96        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
97        characters when looking for a newline.
99     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
101     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
102        in debug output.
104     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
105        long printing in the pcrecpp unittest when running under MinGW.
107     6. ESC_K was left out of the EBCDIC table.
109     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
110        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
111        limit also applies to "virtual nesting" when a pattern is recursive, and in
112        this case 1000 isn't so big. I have been able to remove this limit at the
113        expense of backing off one optimization in certain circumstances. Normally,
114        when pcre_exec() would call its internal match() function recursively and
115        immediately return the result unconditionally, it uses a "tail recursion"
116        feature to save stack. However, when a subpattern that can match an empty
117        string has an unlimited repetition quantifier, it no longer makes this
118        optimization. That gives it a stack frame in which to save the data for
119        checking that an empty string has been matched. Previously this was taken
120        from the 1000-entry workspace that had been reserved. So now there is no
121        explicit limit, but more stack is used.
123     8. Applied Daniel's patches to solve problems with the import/export magic
124        syntax that is required for Windows, and which was going wrong for the
125        pcreposix and pcrecpp parts of the library. These were overlooked when this
126        problem was solved for the main library.
128     9. There were some crude static tests to avoid integer overflow when computing
129        the size of patterns that contain repeated groups with explicit upper
130        limits. As the maximum quantifier is 65535, the maximum group length was
131        set at 30,000 so that the product of these two numbers did not overflow a
132        32-bit integer. However, it turns out that people want to use groups that
133        are longer than 30,000 bytes (though not repeat them that many times).
134        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
135        made it possible to implement the integer overflow checks in a much more
136        dynamic way, which I have now done. The artificial limitation on group
137        length has been removed - we now have only the limit on the total length of
138        the compiled pattern, which depends on the LINK_SIZE setting.
140    10. Fixed a bug in the documentation for get/copy named substring when
141        duplicate names are permitted. If none of the named substrings are set, the
142        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
143        empty string.
145    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
146        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
147        because the ] is interpreted as the first data character and the
148        terminating ] is not found. PCRE has been made compatible with Perl in this
149        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
150        cause memory overwriting.
152    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
153        string has been matched (to stop an infinite loop). It was not recognizing
154        a conditional subpattern that could match an empty string if that
155        subpattern was within another subpattern. For example, it looped when
156        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
157        condition was not nested. This bug has been fixed.
159    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
160        past the start of the subject in the presence of bytes with the top bit
161        set, for example "\x8aBCD".
163    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
164        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
166    14. Optimized (?!) to (*FAIL).
168    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
169        This restricts code points to be within the range 0 to 0x10FFFF, excluding
170        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
171        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
172        does: it's just the validity check that is more restrictive.
174    16. Inserted checks for integer overflows during escape sequence (backslash)
175        processing, and also fixed erroneous offset values for syntax errors during
176        backslash processing.
178    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
179        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
181    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
182        caused an overrun.
184    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
185        something other than just ASCII characters) inside a group that had an
186        unlimited repeat caused a loop at compile time (while checking to see
187        whether the group could match an empty string).
189    20. Debugging a pattern containing \p or \P could cause a crash. For example,
190        [\P{Any}] did so. (Error in the code for printing property names.)
192    21. An orphan \E inside a character class could cause a crash.
194    22. A repeated capturing bracket such as (A)? could cause a wild memory
195        reference during compilation.
197    23. There are several functions in pcre_compile() that scan along a compiled
198        expression for various reasons (e.g. to see if it's fixed length for look
199        behind). There were bugs in these functions when a repeated \p or \P was
200        present in the pattern. These operators have additional parameters compared
201        with \d, etc, and these were not being taken into account when moving along
202        the compiled data. Specifically:
204        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
205            length.
207        (b) An item such as \pL+ within a repeated group could cause crashes or
208            loops.
210        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
211            "reference to non-existent subpattern" error.
213        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
215    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
216        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
218    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
220    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
221        character were causing crashes (broken optimization).
223    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
224        \p or \P) caused a compile-time loop.
226    28. More problems have arisen in unanchored patterns when CRLF is a valid line
227        break. For example, the unstudied pattern [\r\n]A does not match the string
228        "\r\nA" because change 7.0/46 below moves the current point on by two
229        characters after failing to match at the start. However, the pattern \nA
230        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
231        the same is true. There doesn't seem any very clean way out of this, but
232        what I have chosen to do makes the common cases work: PCRE now takes note
233        of whether there can be an explicit match for \r or \n anywhere in the
234        pattern, and if so, 7.0/46 no longer applies. As part of this change,
235        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
236        pattern has explicit CR or LF references.
238    29. Added (*CR) etc for changing newline setting at start of pattern.
241    Version 7.2 19-Jun-07
242    ---------------------
244     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
245        which is apparently normally available under Windows.
247     2. Re-jig the pcregrep tests with different newline settings in an attempt
248        to make them independent of the local environment's newline setting.
250     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
252     4. Some of the "internals" tests were previously cut out when the link size
253        was not 2, because the output contained actual offsets. The recent new
254        "Z" feature of pcretest means that these can be cut out, making the tests
255        usable with all link sizes.
257     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
258        stack recursion. This gives a massive performance boost under BSD, but just
259        a small improvement under Linux. However, it saves one field in the frame
260        in all cases.
262     6. Added more features from the forthcoming Perl 5.10:
264        (a) (?-n) (where n is a string of digits) is a relative subroutine or
265            recursion call. It refers to the nth most recently opened parentheses.
267        (b) (?+n) is also a relative subroutine call; it refers to the nth next
268            to be opened parentheses.
270        (c) Conditions that refer to capturing parentheses can be specified
271            relatively, for example, (?(-2)... or (?(+3)...
273        (d) \K resets the start of the current match so that everything before
274            is not part of it.
276        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
278        (f) \g{name} is another synonym - part of Perl 5.10's unification of
279            reference syntax.
281        (g) (?| introduces a group in which the numbering of parentheses in each
282            alternative starts with the same number.
284        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
286     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
289     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
290        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
291        for detecting groups that can match an empty string.
293     9. A pattern with a very large number of alternatives (more than several
294        hundred) was running out of internal workspace during the pre-compile
295        phase, where pcre_compile() figures out how much memory will be needed. A
296        bit of new cunning has reduced the workspace needed for groups with
297        alternatives. The 1000-alternative test pattern now uses 12 bytes of
298        workspace instead of running out of the 4096 that are available.
300    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
302    11. Applied patch from Google to remove an optimization that didn't quite work.
303        The report of the bug said:
305          pcrecpp::RE("a*").FullMatch("aaa") matches, while
306          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
307          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
309    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
310        it matched the wrong number of bytes.
313    Version 7.1 24-Apr-07
314    ---------------------
316     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
317        that is more "standard", making use of automake and other Autotools. There
318        is some re-arrangement of the files and adjustment of comments consequent
319        on this.
321     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
322        for recursive directory scanning broke on some systems because the files
323        are not scanned in any specific order and on different systems the order
324        was different. A call to "sort" has been inserted into RunGrepTest for the
325        approprate test as a short-term fix. In the longer term there may be an
326        alternative.
328     3. I had an email from Eric Raymond about problems translating some of PCRE's
329        man pages to HTML (despite the fact that I distribute HTML pages, some
330        people do their own conversions for various reasons). The problems
331        concerned the use of low-level troff macros .br and .in. I have therefore
332        removed all such uses from the man pages (some were redundant, some could
333        be replaced by .nf/.fi pairs). The 132html script that I use to generate
334        HTML has been updated to handle .nf/.fi and to complain if it encounters
335        .br or .in.
337     4. Updated comments in configure.ac that get placed in config.h.in and also
338        arranged for config.h to be included in the distribution, with the name
339        config.h.generic, for the benefit of those who have to compile without
340        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
342     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
343        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
344        makevp.bat for the current PCRE, using the additional files
345        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
347     6. A Windows user reported a minor discrepancy with test 2, which turned out
348        to be caused by a trailing space on an input line that had got lost in his
349        copy. The trailing space was an accident, so I've just removed it.
351     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
352        that is needed.
354     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
355        as "const" (a) because they are and (b) because it helps the PHP
356        maintainers who have recently made a script to detect big data structures
357        in the php code that should be moved to the .rodata section. I remembered
358        to update Builducptable as well, so it won't revert if ucptable.h is ever
359        re-created.
361     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
362        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
363        order to be able to cut out the UTF-8 tables in the latter when UTF-8
364        support is not required. This saves 1.5-2K of code, which is important in
365        some applications.
367        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
368        so as not to refer to the tables, even though these functions will never be
369        called when UTF-8 support is disabled. Otherwise there are problems with a
370        shared library.
372    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
374        (a) It was defining its arguments as char * instead of void *.
376        (b) It was assuming that all moves were upwards in memory; this was true
377            a long time ago when I wrote it, but is no longer the case.
379        The emulated memove() is provided for those environments that have neither
380        memmove() nor bcopy(). I didn't think anyone used it these days, but that
381        is clearly not the case, as these two bugs were recently reported.
383    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
384        and Detrail to create the HTML documentation, the .txt form of the man
385        pages, and it removes trailing spaces from listed files. It also creates
386        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
387        case, it wraps all the #defines with #ifndefs. This script should be run
388        before "make dist".
390    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
391        with Unicode property support.
393        (a) For a maximizing quantifier, if the two different cases of the
394            character were of different lengths in their UTF-8 codings (there are
395            some cases like this - I found 11), and the matching function had to
396            back up over a mixture of the two cases, it incorrectly assumed they
397            were both the same length.
399        (b) When PCRE was configured to use the heap rather than the stack for
400            recursion during matching, it was not correctly preserving the data for
401            the other case of a UTF-8 character when checking ahead for a match
402            while processing a minimizing repeat. If the check also involved
403            matching a wide character, but failed, corruption could cause an
404            erroneous result when trying to check for a repeat of the original
405            character.
407    13. Some tidying changes to the testing mechanism:
409        (a) The RunTest script now detects the internal link size and whether there
410            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
411            values substituted by "configure". (The RunGrepTest script already did
412            this for UTF-8.) The configure.ac script no longer substitutes the
413            relevant variables.
415        (b) The debugging options /B and /D in pcretest show the compiled bytecode
416            with length and offset values. This means that the output is different
417            for different internal link sizes. Test 2 is skipped for link sizes
418            other than 2 because of this, bypassing the problem. Unfortunately,
419            there was also a test in test 3 (the locale tests) that used /B and
420            failed for link sizes other than 2. Rather than cut the whole test out,
421            I have added a new /Z option to pcretest that replaces the length and
422            offset values with spaces. This is now used to make test 3 independent
423            of link size. (Test 2 will be tidied up later.)
425    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
426        segmentation fault instead of returning the appropriate error message.
428    15. In multiline mode when the newline sequence was set to "any", the pattern
429        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
430        This doesn't seem right; it now treats the CRLF combination as the line
431        ending, and so does not match in that case. It's only a pattern such as ^$
432        that would hit this one: something like ^ABC$ would have failed after \r
433        and then tried again after \r\n.
435    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
436        in an attempt to make files that differ only in their line terminators
437        compare equal. This works on Linux.
439    17. Under certain error circumstances pcregrep might try to free random memory
440        as it exited. This is now fixed, thanks to valgrind.
442    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
443        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
444        was because its rules for how to advance for /g after matching an empty
445        string at the end of a line did not allow for this case. They now check for
446        it specially.
448    20. pcretest is supposed to handle patterns and data of any length, by
449        extending its buffers when necessary. It was getting this wrong when the
450        buffer for a data line had to be extended.
452    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
453        CRLF as a newline sequence.
455    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
456        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
457        I have nevertheless tidied it up.
459    23. Added some casts to kill warnings from HP-UX ia64 compiler.
461    24. Added a man page for pcre-config.
464    Version 7.0 19-Dec-06
465    ---------------------
467     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
468        moving to gcc 4.1.1.
470     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
471        sys/time.h, which is documented as needed for this function. It doesn't
472        seem to matter on Linux, but it showed up on some releases of OS X.
474     3. It seems that there are systems where bytes whose values are greater than
475        127 match isprint() in the "C" locale. The "C" locale should be the
476        default when a C program starts up. In most systems, only ASCII printing
477        characters match isprint(). This difference caused the output from pcretest
478        to vary, making some of the tests fail. I have changed pcretest so that:
480        (a) When it is outputting text in the compiled version of a pattern, bytes
481            other than 32-126 are always shown as hex escapes.
483        (b) When it is outputting text that is a matched part of a subject string,
484            it does the same, unless a different locale has been set for the match
485            (using the /L modifier). In this case, it uses isprint() to decide.
487     4. Fixed a major bug that caused incorrect computation of the amount of memory
488        required for a compiled pattern when options that changed within the
489        pattern affected the logic of the preliminary scan that determines the
490        length. The relevant options are -x, and -i in UTF-8 mode. The result was
491        that the computed length was too small. The symptoms of this bug were
492        either the PCRE error "internal error: code overflow" from pcre_compile(),
493        or a glibc crash with a message such as "pcretest: free(): invalid next
494        size (fast)". Examples of patterns that provoked this bug (shown in
495        pcretest format) are:
497          /(?-x: )/x
498          /(?x)(?-x: \s*#\s*)/
499          /((?i)[\x{c0}])/8
500          /(?i:[\x{c0}])/8
502        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
503        is now done differently.
505     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
506        wrapper classes; (b) implement a new function in the C++ scanner that is
507        more efficient than the old way of doing things because it avoids levels of
508        recursion in the regex matching; (c) add a paragraph to the documentation
509        for the FullMatch() function.
511     6. The escape sequence \n was being treated as whatever was defined as
512        "newline". Not only was this contrary to the documentation, which states
513        that \n is character 10 (hex 0A), but it also went horribly wrong when
514        "newline" was defined as CRLF. This has been fixed.
516     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
517        was being set to -1 for the "end of line" case (supposedly a value that no
518        character can have). Though this value is never used (the check for end of
519        line is "zero bytes in current character"), it caused compiler complaints.
520        I've changed it to 0xffffffff.
522     8. In pcre_version.c, the version string was being built by a sequence of
523        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
524        string (as it is for production releases) called a macro with an empty
525        argument. The C standard says the result of this is undefined. The gcc
526        compiler treats it as an empty string (which was what was wanted) but it is
527        reported that Visual C gives an error. The source has been hacked around to
528        avoid this problem.
530     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
531        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
532        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
533        of them did).
535    10. Originally, pcretest opened its input and output without "b"; then I was
536        told that "b" was needed in some environments, so it was added for release
537        5.0 to both the input and output. (It makes no difference on Unix-like
538        systems.) Later I was told that it is wrong for the input on Windows. I've
539        now abstracted the modes into two macros, to make it easier to fiddle with
540        them, and removed "b" from the input mode under Windows.
542    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
544    12. Added -help and --help to pcretest as an official way of being reminded
545        of the options.
547    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
548        and pcrecpp.cc because they annoy compilers at high warning levels.
550    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
552    15. Fixed an occurrence of == in configure.ac that should have been = (shell
553        scripts are not C programs :-) and which was not noticed because it works
554        on Linux.
556    16. pcretest is supposed to handle any length of pattern and data line (as one
557        line or as a continued sequence of lines) by extending its input buffer if
558        necessary. This feature was broken for very long pattern lines, leading to
559        a string of junk being passed to pcre_compile() if the pattern was longer
560        than about 50K.
562    17. I have done a major re-factoring of the way pcre_compile() computes the
563        amount of memory needed for a compiled pattern. Previously, there was code
564        that made a preliminary scan of the pattern in order to do this. That was
565        OK when PCRE was new, but as the facilities have expanded, it has become
566        harder and harder to keep it in step with the real compile phase, and there
567        have been a number of bugs (see for example, 4 above). I have now found a
568        cunning way of running the real compile function in a "fake" mode that
569        enables it to compute how much memory it would need, while actually only
570        ever using a few hundred bytes of working memory and without too many
571        tests of the mode. This should make future maintenance and development
572        easier. A side effect of this work is that the limit of 200 on the nesting
573        depth of parentheses has been removed (though this was never a serious
574        limitation, I suspect). However, there is a downside: pcre_compile() now
575        runs more slowly than before (30% or more, depending on the pattern). I
576        hope this isn't a big issue. There is no effect on runtime performance.
578    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
579        newline (only possible for the last line of a file) and it was a
580        pattern that set a locale (followed by /Lsomething), pcretest crashed.
582    19. Added additional timing features to pcretest. (1) The -tm option now times
583        matching only, not compiling. (2) Both -t and -tm can be followed, as a
584        separate command line item, by a number that specifies the number of
585        repeats to use when timing. The default is 50000; this gives better
586        precision, but takes uncomfortably long for very large patterns.
588    20. Extended pcre_study() to be more clever in cases where a branch of a
589        subpattern has no definite first character. For example, (a*|b*)[cd] would
590        previously give no result from pcre_study(). Now it recognizes that the
591        first character must be a, b, c, or d.
593    21. There was an incorrect error "recursive call could loop indefinitely" if
594        a subpattern (or the entire pattern) that was being tested for matching an
595        empty string contained only one non-empty item after a nested subpattern.
596        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
597        incorrectly, because the \d was being skipped in the check.
599    22. The pcretest program now has a new pattern option /B and a command line
600        option -b, which is equivalent to adding /B to every pattern. This causes
601        it to show the compiled bytecode, without the additional information that
602        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
603        is the same as /B/I).
605    23. A new optimization is now able automatically to treat some sequences such
606        as a*b as a*+b. More specifically, if something simple (such as a character
607        or a simple class like \d) has an unlimited quantifier, and is followed by
608        something that cannot possibly match the quantified thing, the quantifier
609        is automatically "possessified".
611    24. A recursive reference to a subpattern whose number was greater than 39
612        went wrong under certain circumstances in UTF-8 mode. This bug could also
613        have affected the operation of pcre_study().
615    25. Realized that a little bit of performance could be had by replacing
616        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
618    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
620    27. Possessive quantifiers such as a++ were previously implemented by turning
621        them into atomic groups such as ($>a+). Now they have their own opcodes,
622        which improves performance. This includes the automatically created ones
623        from 23 above.
625    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
626        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
627        the first matched character to be a colon. This applied both to named and
628        numbered groups.
630    29. The ucpinternal.h header file was missing its idempotency #ifdef.
632    30. I was sent a "project" file called libpcre.a.dev which I understand makes
633        building PCRE on Windows easier, so I have included it in the distribution.
635    31. There is now a check in pcretest against a ridiculously large number being
636        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
637        loop, the loop is abandoned.
639    32. Forward references to subpatterns in conditions such as (?(2)...) where
640        subpattern 2 is defined later cause pcre_compile() to search forwards in
641        the pattern for the relevant set of parentheses. This search went wrong
642        when there were unescaped parentheses in a character class, parentheses
643        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
645    33. "Subroutine" calls and backreferences were previously restricted to
646        referencing subpatterns earlier in the regex. This restriction has now
647        been removed.
649    34. Added a number of extra features that are going to be in Perl 5.10. On the
650        whole, these are just syntactic alternatives for features that PCRE had
651        previously implemented using the Python syntax or my own invention. The
652        other formats are all retained for compatibility.
654        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
655            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
656            also .NET compatible.
658        (b) A recursion or subroutine call to a named group can now be defined as
659            (?&name) as well as (?P>name).
661        (c) A backreference to a named group can now be defined as \k<name> or
662            \k'name' as well as (?P=name). The new forms, as well as being in Perl
663            5.10, are also .NET compatible.
665        (d) A conditional reference to a named group can now use the syntax
666            (?(<name>) or (?('name') as well as (?(name).
668        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
669            groups (named and numbered) that are never evaluated inline, but can be
670            called as "subroutines" from elsewhere. In effect, the DEFINE condition
671            is always false. There may be only one alternative in such a group.
673        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
674            as the simple (?(R). The condition is true only if the most recent
675            recursion is that of the given number or name. It does not search out
676            through the entire recursion stack.
678        (g) The escape \gN or \g{N} has been added, where N is a positive or
679            negative number, specifying an absolute or relative reference.
681    35. Tidied to get rid of some further signed/unsigned compiler warnings and
682        some "unreachable code" warnings.
684    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
685        things, this adds five new scripts.
687    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
688        There were also incompatibilities regarding the handling of \Q..\E inside
689        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
690        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
692    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
693        matches an empty string, and forcibly breaks the loop. There were bugs in
694        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
695        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
696        separate and independent bugs (that affected different cases) have been
697        fixed.
699    39. Refactored the code to abolish the use of different opcodes for small
700        capturing bracket numbers. This is a tidy that I avoided doing when I
701        removed the limit on the number of capturing brackets for 3.5 back in 2001.
702        The new approach is not only tidier, it makes it possible to reduce the
703        memory needed to fix the previous bug (38).
705    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
706        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
707        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
708        mode.
710    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
711        report.
713    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
714        copy construction and assignment in the C++ wrapper.
716    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
717        couple of bugs that could have given wrong results in the "--newline=crlf"
718        case.
720    44. Added a number of casts and did some reorganization of signed/unsigned int
721        variables following suggestions from Dair Grant. Also renamed the variable
722        "this" as "item" because it is a C++ keyword.
724    45. Arranged for dftables to add
726          #include "pcre_internal.h"
728        to pcre_chartables.c because without it, gcc 4.x may remove the array
729        definition from the final binary if PCRE is built into a static library and
730        dead code stripping is activated.
732    46. For an unanchored pattern, if a match attempt fails at the start of a
733        newline sequence, and the newline setting is CRLF or ANY, and the next two
734        characters are CRLF, advance by two characters instead of one.
737    Version 6.7 04-Jul-06
738    ---------------------
740     1. In order to handle tests when input lines are enormously long, pcretest has
741        been re-factored so that it automatically extends its buffers when
742        necessary. The code is crude, but this _is_ just a test program. The
743        default size has been increased from 32K to 50K.
745     2. The code in pcre_study() was using the value of the re argument before
746        testing it for NULL. (Of course, in any sensible call of the function, it
747        won't be NULL.)
749     3. The memmove() emulation function in pcre_internal.h, which is used on
750        systems that lack both memmove() and bcopy() - that is, hardly ever -
751        was missing a "static" storage class specifier.
753     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
754        containing an extended class (one that cannot be represented by a bitmap
755        because it contains high-valued characters or Unicode property items, e.g.
756        [\pZ]). Almost always one would set UTF-8 mode when processing such a
757        pattern, but PCRE should not loop if you do not (it no longer does).
758        [Detail: two cases were found: (a) a repeated subpattern containing an
759        extended class; (b) a recursive reference to a subpattern that followed a
760        previous extended class. It wasn't skipping over the extended class
761        correctly when UTF-8 mode was not set.]
763     5. A negated single-character class was not being recognized as fixed-length
764        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
765        compile error "lookbehind assertion is not fixed length".
767     6. The RunPerlTest auxiliary script was showing an unexpected difference
768        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
769        write a Perl script that can interpret lines of an input file either as
770        byte characters or as UTF-8, which is what "perltest" was being required to
771        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
772        can't do is switch easily at run time between having the "use utf8;" pragma
773        or not. In the end, I fudged it by using the RunPerlTest script to insert
774        "use utf8;" explicitly for the UTF-8 tests.
776     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
777        the end of the subject string, contrary to the documentation and to what
778        Perl does. This was true of both matching functions. Now it matches only at
779        the start of the subject and immediately after *internal* newlines.
781     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
782        a pointer to an int instead of a pointer to an unsigned long int. This
783        caused problems on 64-bit systems.
785     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
786        instance of the 'standard' template library not being so standard".
788    10. There was no check on the number of named subpatterns nor the maximum
789        length of a subpattern name. The product of these values is used to compute
790        the size of the memory block for a compiled pattern. By supplying a very
791        long subpattern name and a large number of named subpatterns, the size
792        computation could be caused to overflow. This is now prevented by limiting
793        the length of names to 32 characters, and the number of named subpatterns
794        to 10,000.
796    11. Subpatterns that are repeated with specific counts have to be replicated in
797        the compiled pattern. The size of memory for this was computed from the
798        length of the subpattern and the repeat count. The latter is limited to
799        65535, but there was no limit on the former, meaning that integer overflow
800        could in principle occur. The compiled length of a repeated subpattern is
801        now limited to 30,000 bytes in order to prevent this.
803    12. Added the optional facility to have named substrings with the same name.
805    13. Added the ability to use a named substring as a condition, using the
806        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
807        are numbers (not recommended). Forward references are permitted.
809    14. Added forward references in named backreferences (if you see what I mean).
811    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
812        pattern could run off the end of the subject. For example, the pattern
813        "(?s)(.{1,5})"8 did this with the subject "ab".
815    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
816        PCRE_CASELESS was set when matching characters that were quantified with ?
817        or *.
819    17. A character class other than a single negated character that had a minimum
820        but no maximum quantifier - for example [ab]{6,} - was not handled
821        correctly by pce_dfa_exec(). It would match only one character.
823    18. A valid (though odd) pattern that looked like a POSIX character
824        class but used an invalid character after [ (for example [[,abc,]]) caused
825        pcre_compile() to give the error "Failed: internal error: code overflow" or
826        in some cases to crash with a glibc free() error. This could even happen if
827        the pattern terminated after [[ but there just happened to be a sequence of
828        letters, a binary zero, and a closing ] in the memory that followed.
830    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
831        over the years. Originally (before any Unicode support), just the bottom 8
832        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
833        output from "man perlunicode" includes this:
835          The regular expression compiler produces polymorphic opcodes.  That
836          is, the pattern adapts to the data and automatically switches to
837          the Unicode character scheme when presented with Unicode data--or
838          instead uses a traditional byte scheme when presented with byte
839          data.
841        Sadly, a wide octal escape does not cause a switch, and in a string with
842        no other multibyte characters, these octal escapes are treated as before.
843        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
844        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
845        Unicode string.
847        I have not perpetrated such confusion in PCRE. Up till now, it took just
848        the bottom 8 bits, as in old Perl. I have now made octal escapes with
849        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
850        translate to the appropriate multibyte character.
852    29. Applied some refactoring to reduce the number of warnings from Microsoft
853        and Borland compilers. This has included removing the fudge introduced
854        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
855        a warning about an unused variable.
857    21. PCRE has not included VT (character 0x0b) in the set of whitespace
858        characters since release 4.0, because Perl (from release 5.004) does not.
859        [Or at least, is documented not to: some releases seem to be in conflict
860        with the documentation.] However, when a pattern was studied with
861        pcre_study() and all its branches started with \s, PCRE still included VT
862        as a possible starting character. Of course, this did no harm; it just
863        caused an unnecessary match attempt.
865    22. Removed a now-redundant internal flag bit that recorded the fact that case
866        dependency changed within the pattern. This was once needed for "required
867        byte" processing, but is no longer used. This recovers a now-scarce options
868        bit. Also moved the least significant internal flag bit to the most-
869        significant bit of the word, which was not previously used (hangover from
870        the days when it was an int rather than a uint) to free up another bit for
871        the future.
873    23. Added support for CRLF line endings as well as CR and LF. As well as the
874        default being selectable at build time, it can now be changed at runtime
875        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
876        specify that it is scanning data with non-default line endings.
878    24. Changed the definition of CXXLINK to make it agree with the definition of
879        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
881    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
882        recursions. This makes a big different to stack usage for some patterns.
884    26. If a subpattern containing a named recursion or subroutine reference such
885        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
886        the space required for the compiled pattern went wrong and gave too small a
887        value. Depending on the environment, this could lead to "Failed: internal
888        error: code overflow at offset 49" or "glibc detected double free or
889        corruption" errors.
891    27. Applied patches from Google (a) to support the new newline modes and (b) to
892        advance over multibyte UTF-8 characters in GlobalReplace.
894    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
895        difference for some implementation of PCRE in some Windows version.
897    29. Added some extra testing facilities to pcretest:
899        \q<number>   in a data line sets the "match limit" value
900        \Q<number>   in a data line sets the "match recursion limt" value
901        -S <number>  sets the stack size, where <number> is in megabytes
903        The -S option isn't available for Windows.
906    Version 6.6 06-Feb-06
907    ---------------------
909     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
910        in pcreposix.h. I have copied the definition from pcre.h.
912     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
913        because pcre.h is no longer a built file.
915     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
916        not normally included in the compiled code.
919  Version 6.5 01-Feb-06  Version 6.5 01-Feb-06
920  ---------------------  ---------------------

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