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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 7.5 12-Nov-07
5    ---------------------
6    
7    1.  Applied a patch from Craig: "This patch makes it possible to 'ignore'
8        values in parens when parsing an RE using the C++ wrapper."
9    
10    2.  Negative specials like \S did not work in character classes in UTF-8 mode.
11        Characters greater than 255 were excluded from the class instead of being
12        included.
13    
14    3.  The same bug as (2) above applied to negated POSIX classes such as
15        [:^space:].
16    
17    4.  PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
18        defined or documented. It seems to have been a typo for PCRE_STATIC, so
19        I have changed it.
20    
21    5.  The construct (?&) was not diagnosed as a syntax error (it referenced the
22        first named subpattern) and a construct such as (?&a) would reference the
23        first named subpattern whose name started with "a" (in other words, the
24        length check was missing). Both these problems are fixed. "Subpattern name
25        expected" is now given for (?&) (a zero-length name), and this patch also
26        makes it give the same error for \k'' (previously it complained that that
27        was a reference to a non-existent subpattern).
28    
29    6.  The erroneous patterns (?+-a) and (?-+a) give different error messages;
30        this is right because (?- can be followed by option settings as well as by
31        digits. I have, however, made the messages clearer.
32    
33    7.  Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
34        than the number used in the conditional) now cause a compile-time error.
35        This is actually not compatible with Perl, which accepts such patterns, but
36        treats the conditional as always being FALSE (as PCRE used to), but it
37        seems to me that giving a diagnostic is better.
38    
39    8.  Change "alphameric" to the more common word "alphanumeric" in comments
40        and messages.
41    
42    9.  Fix two occurrences of "backslash" in comments that should have been
43        "backspace".
44    
45    10. Remove two redundant lines of code that can never be obeyed (their function
46        was moved elsewhere).
47    
48    11. The program that makes PCRE's Unicode character property table had a bug
49        which caused it to generate incorrect table entries for sequences of
50        characters that have the same character type, but are in different scripts.
51        It amalgamated them into a single range, with the script of the first of
52        them. In other words, some characters were in the wrong script. There were
53        thirteen such cases, affecting characters in the following ranges:
54    
55          U+002b0 - U+002c1
56          U+0060c - U+0060d
57          U+0061e - U+00612
58          U+0064b - U+0065e
59          U+0074d - U+0076d
60          U+01800 - U+01805
61          U+01d00 - U+01d77
62          U+01d9b - U+01dbf
63          U+0200b - U+0200f
64          U+030fc - U+030fe
65          U+03260 - U+0327f
66          U+0fb46 - U+0fbb1
67          U+10450 - U+1049d
68    
69    
70    Version 7.4 21-Sep-07
71    ---------------------
72    
73    1.  Change 7.3/28 was implemented for classes by looking at the bitmap. This
74        means that a class such as [\s] counted as "explicit reference to CR or
75        LF". That isn't really right - the whole point of the change was to try to
76        help when there was an actual mention of one of the two characters. So now
77        the change happens only if \r or \n (or a literal CR or LF) character is
78        encountered.
79    
80    2.  The 32-bit options word was also used for 6 internal flags, but the numbers
81        of both had grown to the point where there were only 3 bits left.
82        Fortunately, there was spare space in the data structure, and so I have
83        moved the internal flags into a new 16-bit field to free up more option
84        bits.
85    
86    3.  The appearance of (?J) at the start of a pattern set the DUPNAMES option,
87        but did not set the internal JCHANGED flag - either of these is enough to
88        control the way the "get" function works - but the PCRE_INFO_JCHANGED
89        facility is supposed to tell if (?J) was ever used, so now (?J) at the
90        start sets both bits.
91    
92    4.  Added options (at build time, compile time, exec time) to change \R from
93        matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
94    
95    5.  doc/pcresyntax.html was missing from the distribution.
96    
97    6.  Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
98        compatibility, even though it is no longer used.
99    
100    7.  Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
101        strtoull to pcrecpp.cc to select the available functions in WIN32 when the
102        windows.h file is present (where different names are used). [This was
103        reversed later after testing - see 16 below.]
104    
105    8.  Changed all #include <config.h> to #include "config.h". There were also
106        some further <pcre.h> cases that I changed to "pcre.h".
107    
108    9.  When pcregrep was used with the --colour option, it missed the line ending
109        sequence off the lines that it output.
110    
111    10. It was pointed out to me that arrays of string pointers cause lots of
112        relocations when a shared library is dynamically loaded. A technique of
113        using a single long string with a table of offsets can drastically reduce
114        these. I have refactored PCRE in four places to do this. The result is
115        dramatic:
116    
117          Originally:                          290
118          After changing UCP table:            187
119          After changing error message table:   43
120          After changing table of "verbs"       36
121          After changing table of Posix names   22
122    
123        Thanks to the folks working on Gregex for glib for this insight.
124    
125    11. --disable-stack-for-recursion caused compiling to fail unless -enable-
126        unicode-properties was also set.
127    
128    12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
129    
130    13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
131        checked only for CRLF.
132    
133    14. Added casts to pcretest.c to avoid compiler warnings.
134    
135    15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
136    
137    16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
138        and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
139        entirely. This removes changes made in 7 above.
140    
141    17. The CMake files have been updated, and there is now more information about
142        building with CMake in the NON-UNIX-USE document.
143    
144    
145    Version 7.3 28-Aug-07
146    ---------------------
147    
148     1. In the rejigging of the build system that eventually resulted in 7.1, the
149        line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
150        brackets there is not right, since it causes compilers to look for an
151        installed pcre.h, not the version that is in the source that is being
152        compiled (which of course may be different). I have changed it back to:
153    
154          #include "pcre.h"
155    
156        I have a vague recollection that the change was concerned with compiling in
157        different directories, but in the new build system, that is taken care of
158        by the VPATH setting the Makefile.
159    
160     2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
161        when the subject happened to end in the byte 0x85 (e.g. if the last
162        character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
163        characters but of course it shouldn't be taken as a newline when it is part
164        of another character. The bug was that, for an unlimited repeat of . in
165        not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
166        characters when looking for a newline.
167    
168     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
169    
170     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
171        in debug output.
172    
173     5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
174        long printing in the pcrecpp unittest when running under MinGW.
175    
176     6. ESC_K was left out of the EBCDIC table.
177    
178     7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
179        parentheses; I made it 1000, which seemed large enough. Unfortunately, the
180        limit also applies to "virtual nesting" when a pattern is recursive, and in
181        this case 1000 isn't so big. I have been able to remove this limit at the
182        expense of backing off one optimization in certain circumstances. Normally,
183        when pcre_exec() would call its internal match() function recursively and
184        immediately return the result unconditionally, it uses a "tail recursion"
185        feature to save stack. However, when a subpattern that can match an empty
186        string has an unlimited repetition quantifier, it no longer makes this
187        optimization. That gives it a stack frame in which to save the data for
188        checking that an empty string has been matched. Previously this was taken
189        from the 1000-entry workspace that had been reserved. So now there is no
190        explicit limit, but more stack is used.
191    
192     8. Applied Daniel's patches to solve problems with the import/export magic
193        syntax that is required for Windows, and which was going wrong for the
194        pcreposix and pcrecpp parts of the library. These were overlooked when this
195        problem was solved for the main library.
196    
197     9. There were some crude static tests to avoid integer overflow when computing
198        the size of patterns that contain repeated groups with explicit upper
199        limits. As the maximum quantifier is 65535, the maximum group length was
200        set at 30,000 so that the product of these two numbers did not overflow a
201        32-bit integer. However, it turns out that people want to use groups that
202        are longer than 30,000 bytes (though not repeat them that many times).
203        Change 7.0/17 (the refactoring of the way the pattern size is computed) has
204        made it possible to implement the integer overflow checks in a much more
205        dynamic way, which I have now done. The artificial limitation on group
206        length has been removed - we now have only the limit on the total length of
207        the compiled pattern, which depends on the LINK_SIZE setting.
208    
209    10. Fixed a bug in the documentation for get/copy named substring when
210        duplicate names are permitted. If none of the named substrings are set, the
211        functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
212        empty string.
213    
214    11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
215        instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
216        because the ] is interpreted as the first data character and the
217        terminating ] is not found. PCRE has been made compatible with Perl in this
218        regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
219        cause memory overwriting.
220    
221    10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
222        string has been matched (to stop an infinite loop). It was not recognizing
223        a conditional subpattern that could match an empty string if that
224        subpattern was within another subpattern. For example, it looped when
225        trying to match  (((?(1)X|))*)  but it was OK with  ((?(1)X|)*)  where the
226        condition was not nested. This bug has been fixed.
227    
228    12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
229        past the start of the subject in the presence of bytes with the top bit
230        set, for example "\x8aBCD".
231    
232    13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
233        (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
234    
235    14. Optimized (?!) to (*FAIL).
236    
237    15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
238        This restricts code points to be within the range 0 to 0x10FFFF, excluding
239        the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
240        full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
241        does: it's just the validity check that is more restrictive.
242    
243    16. Inserted checks for integer overflows during escape sequence (backslash)
244        processing, and also fixed erroneous offset values for syntax errors during
245        backslash processing.
246    
247    17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
248        for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
249    
250    18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
251        caused an overrun.
252    
253    19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
254        something other than just ASCII characters) inside a group that had an
255        unlimited repeat caused a loop at compile time (while checking to see
256        whether the group could match an empty string).
257    
258    20. Debugging a pattern containing \p or \P could cause a crash. For example,
259        [\P{Any}] did so. (Error in the code for printing property names.)
260    
261    21. An orphan \E inside a character class could cause a crash.
262    
263    22. A repeated capturing bracket such as (A)? could cause a wild memory
264        reference during compilation.
265    
266    23. There are several functions in pcre_compile() that scan along a compiled
267        expression for various reasons (e.g. to see if it's fixed length for look
268        behind). There were bugs in these functions when a repeated \p or \P was
269        present in the pattern. These operators have additional parameters compared
270        with \d, etc, and these were not being taken into account when moving along
271        the compiled data. Specifically:
272    
273        (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
274            length.
275    
276        (b) An item such as \pL+ within a repeated group could cause crashes or
277            loops.
278    
279        (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
280            "reference to non-existent subpattern" error.
281    
282        (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
283    
284    24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
285        characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
286    
287    25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
288    
289    26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
290        character were causing crashes (broken optimization).
291    
292    27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
293        \p or \P) caused a compile-time loop.
294    
295    28. More problems have arisen in unanchored patterns when CRLF is a valid line
296        break. For example, the unstudied pattern [\r\n]A does not match the string
297        "\r\nA" because change 7.0/46 below moves the current point on by two
298        characters after failing to match at the start. However, the pattern \nA
299        *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
300        the same is true. There doesn't seem any very clean way out of this, but
301        what I have chosen to do makes the common cases work: PCRE now takes note
302        of whether there can be an explicit match for \r or \n anywhere in the
303        pattern, and if so, 7.0/46 no longer applies. As part of this change,
304        there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
305        pattern has explicit CR or LF references.
306    
307    29. Added (*CR) etc for changing newline setting at start of pattern.
308    
309    
310    Version 7.2 19-Jun-07
311    ---------------------
312    
313     1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
314        which is apparently normally available under Windows.
315    
316     2. Re-jig the pcregrep tests with different newline settings in an attempt
317        to make them independent of the local environment's newline setting.
318    
319     3. Add code to configure.ac to remove -g from the CFLAGS default settings.
320    
321     4. Some of the "internals" tests were previously cut out when the link size
322        was not 2, because the output contained actual offsets. The recent new
323        "Z" feature of pcretest means that these can be cut out, making the tests
324        usable with all link sizes.
325    
326     5. Implemented Stan Switzer's goto replacement for longjmp() when not using
327        stack recursion. This gives a massive performance boost under BSD, but just
328        a small improvement under Linux. However, it saves one field in the frame
329        in all cases.
330    
331     6. Added more features from the forthcoming Perl 5.10:
332    
333        (a) (?-n) (where n is a string of digits) is a relative subroutine or
334            recursion call. It refers to the nth most recently opened parentheses.
335    
336        (b) (?+n) is also a relative subroutine call; it refers to the nth next
337            to be opened parentheses.
338    
339        (c) Conditions that refer to capturing parentheses can be specified
340            relatively, for example, (?(-2)... or (?(+3)...
341    
342        (d) \K resets the start of the current match so that everything before
343            is not part of it.
344    
345        (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
346    
347        (f) \g{name} is another synonym - part of Perl 5.10's unification of
348            reference syntax.
349    
350        (g) (?| introduces a group in which the numbering of parentheses in each
351            alternative starts with the same number.
352    
353        (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
354    
355     7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
356        PCRE_INFO_JCHANGED.
357    
358     8. A pattern such as  (.*(.)?)*  caused pcre_exec() to fail by either not
359        terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
360        for detecting groups that can match an empty string.
361    
362     9. A pattern with a very large number of alternatives (more than several
363        hundred) was running out of internal workspace during the pre-compile
364        phase, where pcre_compile() figures out how much memory will be needed. A
365        bit of new cunning has reduced the workspace needed for groups with
366        alternatives. The 1000-alternative test pattern now uses 12 bytes of
367        workspace instead of running out of the 4096 that are available.
368    
369    10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
370    
371    11. Applied patch from Google to remove an optimization that didn't quite work.
372        The report of the bug said:
373    
374          pcrecpp::RE("a*").FullMatch("aaa") matches, while
375          pcrecpp::RE("a*?").FullMatch("aaa") does not, and
376          pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
377    
378    12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
379        it matched the wrong number of bytes.
380    
381    
382    Version 7.1 24-Apr-07
383    ---------------------
384    
385     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
386        that is more "standard", making use of automake and other Autotools. There
387        is some re-arrangement of the files and adjustment of comments consequent
388        on this.
389    
390     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
391        for recursive directory scanning broke on some systems because the files
392        are not scanned in any specific order and on different systems the order
393        was different. A call to "sort" has been inserted into RunGrepTest for the
394        approprate test as a short-term fix. In the longer term there may be an
395        alternative.
396    
397     3. I had an email from Eric Raymond about problems translating some of PCRE's
398        man pages to HTML (despite the fact that I distribute HTML pages, some
399        people do their own conversions for various reasons). The problems
400        concerned the use of low-level troff macros .br and .in. I have therefore
401        removed all such uses from the man pages (some were redundant, some could
402        be replaced by .nf/.fi pairs). The 132html script that I use to generate
403        HTML has been updated to handle .nf/.fi and to complain if it encounters
404        .br or .in.
405    
406     4. Updated comments in configure.ac that get placed in config.h.in and also
407        arranged for config.h to be included in the distribution, with the name
408        config.h.generic, for the benefit of those who have to compile without
409        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
410    
411     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
412        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
413        makevp.bat for the current PCRE, using the additional files
414        makevp_c.txt, makevp_l.txt, and pcregexp.pas.
415    
416     6. A Windows user reported a minor discrepancy with test 2, which turned out
417        to be caused by a trailing space on an input line that had got lost in his
418        copy. The trailing space was an accident, so I've just removed it.
419    
420     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
421        that is needed.
422    
423     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
424        as "const" (a) because they are and (b) because it helps the PHP
425        maintainers who have recently made a script to detect big data structures
426        in the php code that should be moved to the .rodata section. I remembered
427        to update Builducptable as well, so it won't revert if ucptable.h is ever
428        re-created.
429    
430     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
431        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
432        order to be able to cut out the UTF-8 tables in the latter when UTF-8
433        support is not required. This saves 1.5-2K of code, which is important in
434        some applications.
435    
436        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
437        so as not to refer to the tables, even though these functions will never be
438        called when UTF-8 support is disabled. Otherwise there are problems with a
439        shared library.
440    
441    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
442    
443        (a) It was defining its arguments as char * instead of void *.
444    
445        (b) It was assuming that all moves were upwards in memory; this was true
446            a long time ago when I wrote it, but is no longer the case.
447    
448        The emulated memove() is provided for those environments that have neither
449        memmove() nor bcopy(). I didn't think anyone used it these days, but that
450        is clearly not the case, as these two bugs were recently reported.
451    
452    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
453        and Detrail to create the HTML documentation, the .txt form of the man
454        pages, and it removes trailing spaces from listed files. It also creates
455        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
456        case, it wraps all the #defines with #ifndefs. This script should be run
457        before "make dist".
458    
459    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
460        with Unicode property support.
461    
462        (a) For a maximizing quantifier, if the two different cases of the
463            character were of different lengths in their UTF-8 codings (there are
464            some cases like this - I found 11), and the matching function had to
465            back up over a mixture of the two cases, it incorrectly assumed they
466            were both the same length.
467    
468        (b) When PCRE was configured to use the heap rather than the stack for
469            recursion during matching, it was not correctly preserving the data for
470            the other case of a UTF-8 character when checking ahead for a match
471            while processing a minimizing repeat. If the check also involved
472            matching a wide character, but failed, corruption could cause an
473            erroneous result when trying to check for a repeat of the original
474            character.
475    
476    13. Some tidying changes to the testing mechanism:
477    
478        (a) The RunTest script now detects the internal link size and whether there
479            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
480            values substituted by "configure". (The RunGrepTest script already did
481            this for UTF-8.) The configure.ac script no longer substitutes the
482            relevant variables.
483    
484        (b) The debugging options /B and /D in pcretest show the compiled bytecode
485            with length and offset values. This means that the output is different
486            for different internal link sizes. Test 2 is skipped for link sizes
487            other than 2 because of this, bypassing the problem. Unfortunately,
488            there was also a test in test 3 (the locale tests) that used /B and
489            failed for link sizes other than 2. Rather than cut the whole test out,
490            I have added a new /Z option to pcretest that replaces the length and
491            offset values with spaces. This is now used to make test 3 independent
492            of link size. (Test 2 will be tidied up later.)
493    
494    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
495        segmentation fault instead of returning the appropriate error message.
496    
497    15. In multiline mode when the newline sequence was set to "any", the pattern
498        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
499        This doesn't seem right; it now treats the CRLF combination as the line
500        ending, and so does not match in that case. It's only a pattern such as ^$
501        that would hit this one: something like ^ABC$ would have failed after \r
502        and then tried again after \r\n.
503    
504    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
505        in an attempt to make files that differ only in their line terminators
506        compare equal. This works on Linux.
507    
508    17. Under certain error circumstances pcregrep might try to free random memory
509        as it exited. This is now fixed, thanks to valgrind.
510    
511    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
512        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
513        was because its rules for how to advance for /g after matching an empty
514        string at the end of a line did not allow for this case. They now check for
515        it specially.
516    
517    20. pcretest is supposed to handle patterns and data of any length, by
518        extending its buffers when necessary. It was getting this wrong when the
519        buffer for a data line had to be extended.
520    
521    21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
522        CRLF as a newline sequence.
523    
524    22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
525        out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
526        I have nevertheless tidied it up.
527    
528    23. Added some casts to kill warnings from HP-UX ia64 compiler.
529    
530    24. Added a man page for pcre-config.
531    
532    
533    Version 7.0 19-Dec-06
534    ---------------------
535    
536     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
537        moving to gcc 4.1.1.
538    
539     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
540        sys/time.h, which is documented as needed for this function. It doesn't
541        seem to matter on Linux, but it showed up on some releases of OS X.
542    
543     3. It seems that there are systems where bytes whose values are greater than
544        127 match isprint() in the "C" locale. The "C" locale should be the
545        default when a C program starts up. In most systems, only ASCII printing
546        characters match isprint(). This difference caused the output from pcretest
547        to vary, making some of the tests fail. I have changed pcretest so that:
548    
549        (a) When it is outputting text in the compiled version of a pattern, bytes
550            other than 32-126 are always shown as hex escapes.
551    
552        (b) When it is outputting text that is a matched part of a subject string,
553            it does the same, unless a different locale has been set for the match
554            (using the /L modifier). In this case, it uses isprint() to decide.
555    
556     4. Fixed a major bug that caused incorrect computation of the amount of memory
557        required for a compiled pattern when options that changed within the
558        pattern affected the logic of the preliminary scan that determines the
559        length. The relevant options are -x, and -i in UTF-8 mode. The result was
560        that the computed length was too small. The symptoms of this bug were
561        either the PCRE error "internal error: code overflow" from pcre_compile(),
562        or a glibc crash with a message such as "pcretest: free(): invalid next
563        size (fast)". Examples of patterns that provoked this bug (shown in
564        pcretest format) are:
565    
566          /(?-x: )/x
567          /(?x)(?-x: \s*#\s*)/
568          /((?i)[\x{c0}])/8
569          /(?i:[\x{c0}])/8
570    
571        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
572        is now done differently.
573    
574     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
575        wrapper classes; (b) implement a new function in the C++ scanner that is
576        more efficient than the old way of doing things because it avoids levels of
577        recursion in the regex matching; (c) add a paragraph to the documentation
578        for the FullMatch() function.
579    
580     6. The escape sequence \n was being treated as whatever was defined as
581        "newline". Not only was this contrary to the documentation, which states
582        that \n is character 10 (hex 0A), but it also went horribly wrong when
583        "newline" was defined as CRLF. This has been fixed.
584    
585     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
586        was being set to -1 for the "end of line" case (supposedly a value that no
587        character can have). Though this value is never used (the check for end of
588        line is "zero bytes in current character"), it caused compiler complaints.
589        I've changed it to 0xffffffff.
590    
591     8. In pcre_version.c, the version string was being built by a sequence of
592        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
593        string (as it is for production releases) called a macro with an empty
594        argument. The C standard says the result of this is undefined. The gcc
595        compiler treats it as an empty string (which was what was wanted) but it is
596        reported that Visual C gives an error. The source has been hacked around to
597        avoid this problem.
598    
599     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
600        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
601        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
602        of them did).
603    
604    10. Originally, pcretest opened its input and output without "b"; then I was
605        told that "b" was needed in some environments, so it was added for release
606        5.0 to both the input and output. (It makes no difference on Unix-like
607        systems.) Later I was told that it is wrong for the input on Windows. I've
608        now abstracted the modes into two macros, to make it easier to fiddle with
609        them, and removed "b" from the input mode under Windows.
610    
611    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
612    
613    12. Added -help and --help to pcretest as an official way of being reminded
614        of the options.
615    
616    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
617        and pcrecpp.cc because they annoy compilers at high warning levels.
618    
619    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
620    
621    15. Fixed an occurrence of == in configure.ac that should have been = (shell
622        scripts are not C programs :-) and which was not noticed because it works
623        on Linux.
624    
625    16. pcretest is supposed to handle any length of pattern and data line (as one
626        line or as a continued sequence of lines) by extending its input buffer if
627        necessary. This feature was broken for very long pattern lines, leading to
628        a string of junk being passed to pcre_compile() if the pattern was longer
629        than about 50K.
630    
631    17. I have done a major re-factoring of the way pcre_compile() computes the
632        amount of memory needed for a compiled pattern. Previously, there was code
633        that made a preliminary scan of the pattern in order to do this. That was
634        OK when PCRE was new, but as the facilities have expanded, it has become
635        harder and harder to keep it in step with the real compile phase, and there
636        have been a number of bugs (see for example, 4 above). I have now found a
637        cunning way of running the real compile function in a "fake" mode that
638        enables it to compute how much memory it would need, while actually only
639        ever using a few hundred bytes of working memory and without too many
640        tests of the mode. This should make future maintenance and development
641        easier. A side effect of this work is that the limit of 200 on the nesting
642        depth of parentheses has been removed (though this was never a serious
643        limitation, I suspect). However, there is a downside: pcre_compile() now
644        runs more slowly than before (30% or more, depending on the pattern). I
645        hope this isn't a big issue. There is no effect on runtime performance.
646    
647    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
648        newline (only possible for the last line of a file) and it was a
649        pattern that set a locale (followed by /Lsomething), pcretest crashed.
650    
651    19. Added additional timing features to pcretest. (1) The -tm option now times
652        matching only, not compiling. (2) Both -t and -tm can be followed, as a
653        separate command line item, by a number that specifies the number of
654        repeats to use when timing. The default is 50000; this gives better
655        precision, but takes uncomfortably long for very large patterns.
656    
657    20. Extended pcre_study() to be more clever in cases where a branch of a
658        subpattern has no definite first character. For example, (a*|b*)[cd] would
659        previously give no result from pcre_study(). Now it recognizes that the
660        first character must be a, b, c, or d.
661    
662    21. There was an incorrect error "recursive call could loop indefinitely" if
663        a subpattern (or the entire pattern) that was being tested for matching an
664        empty string contained only one non-empty item after a nested subpattern.
665        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
666        incorrectly, because the \d was being skipped in the check.
667    
668    22. The pcretest program now has a new pattern option /B and a command line
669        option -b, which is equivalent to adding /B to every pattern. This causes
670        it to show the compiled bytecode, without the additional information that
671        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
672        is the same as /B/I).
673    
674    23. A new optimization is now able automatically to treat some sequences such
675        as a*b as a*+b. More specifically, if something simple (such as a character
676        or a simple class like \d) has an unlimited quantifier, and is followed by
677        something that cannot possibly match the quantified thing, the quantifier
678        is automatically "possessified".
679    
680    24. A recursive reference to a subpattern whose number was greater than 39
681        went wrong under certain circumstances in UTF-8 mode. This bug could also
682        have affected the operation of pcre_study().
683    
684    25. Realized that a little bit of performance could be had by replacing
685        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
686    
687    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
688    
689    27. Possessive quantifiers such as a++ were previously implemented by turning
690        them into atomic groups such as ($>a+). Now they have their own opcodes,
691        which improves performance. This includes the automatically created ones
692        from 23 above.
693    
694    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
695        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
696        the first matched character to be a colon. This applied both to named and
697        numbered groups.
698    
699    29. The ucpinternal.h header file was missing its idempotency #ifdef.
700    
701    30. I was sent a "project" file called libpcre.a.dev which I understand makes
702        building PCRE on Windows easier, so I have included it in the distribution.
703    
704    31. There is now a check in pcretest against a ridiculously large number being
705        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
706        loop, the loop is abandoned.
707    
708    32. Forward references to subpatterns in conditions such as (?(2)...) where
709        subpattern 2 is defined later cause pcre_compile() to search forwards in
710        the pattern for the relevant set of parentheses. This search went wrong
711        when there were unescaped parentheses in a character class, parentheses
712        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
713    
714    33. "Subroutine" calls and backreferences were previously restricted to
715        referencing subpatterns earlier in the regex. This restriction has now
716        been removed.
717    
718    34. Added a number of extra features that are going to be in Perl 5.10. On the
719        whole, these are just syntactic alternatives for features that PCRE had
720        previously implemented using the Python syntax or my own invention. The
721        other formats are all retained for compatibility.
722    
723        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
724            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
725            also .NET compatible.
726    
727        (b) A recursion or subroutine call to a named group can now be defined as
728            (?&name) as well as (?P>name).
729    
730        (c) A backreference to a named group can now be defined as \k<name> or
731            \k'name' as well as (?P=name). The new forms, as well as being in Perl
732            5.10, are also .NET compatible.
733    
734        (d) A conditional reference to a named group can now use the syntax
735            (?(<name>) or (?('name') as well as (?(name).
736    
737        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
738            groups (named and numbered) that are never evaluated inline, but can be
739            called as "subroutines" from elsewhere. In effect, the DEFINE condition
740            is always false. There may be only one alternative in such a group.
741    
742        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
743            as the simple (?(R). The condition is true only if the most recent
744            recursion is that of the given number or name. It does not search out
745            through the entire recursion stack.
746    
747        (g) The escape \gN or \g{N} has been added, where N is a positive or
748            negative number, specifying an absolute or relative reference.
749    
750    35. Tidied to get rid of some further signed/unsigned compiler warnings and
751        some "unreachable code" warnings.
752    
753    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
754        things, this adds five new scripts.
755    
756    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
757        There were also incompatibilities regarding the handling of \Q..\E inside
758        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
759        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
760    
761    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
762        matches an empty string, and forcibly breaks the loop. There were bugs in
763        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
764        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
765        separate and independent bugs (that affected different cases) have been
766        fixed.
767    
768    39. Refactored the code to abolish the use of different opcodes for small
769        capturing bracket numbers. This is a tidy that I avoided doing when I
770        removed the limit on the number of capturing brackets for 3.5 back in 2001.
771        The new approach is not only tidier, it makes it possible to reduce the
772        memory needed to fix the previous bug (38).
773    
774    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
775        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
776        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
777        mode.
778    
779    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
780        report.
781    
782    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
783        copy construction and assignment in the C++ wrapper.
784    
785    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
786        couple of bugs that could have given wrong results in the "--newline=crlf"
787        case.
788    
789    44. Added a number of casts and did some reorganization of signed/unsigned int
790        variables following suggestions from Dair Grant. Also renamed the variable
791        "this" as "item" because it is a C++ keyword.
792    
793    45. Arranged for dftables to add
794    
795          #include "pcre_internal.h"
796    
797        to pcre_chartables.c because without it, gcc 4.x may remove the array
798        definition from the final binary if PCRE is built into a static library and
799        dead code stripping is activated.
800    
801    46. For an unanchored pattern, if a match attempt fails at the start of a
802        newline sequence, and the newline setting is CRLF or ANY, and the next two
803        characters are CRLF, advance by two characters instead of one.
804    
805    
806  Version 6.7 04-Jul-06  Version 6.7 04-Jul-06
807  ---------------------  ---------------------
808    

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