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revision 75 by nigel, Sat Feb 24 21:40:37 2007 UTC revision 123 by ph10, Mon Mar 12 15:19:06 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 7.1 12-Mar-07
5    ---------------------
6    
7     1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
8        that is more "standard", making use of automake and other Autotools. There
9        is some re-arrangement of the files and adjustment of comments consequent
10        on this.
11    
12     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
13        for recursive directory scanning broke on some systems because the files
14        are not scanned in any specific order and on different systems the order
15        was different. A call to "sort" has been inserted into RunGrepTest for the
16        approprate test as a short-term fix. In the longer term there may be an
17        alternative.
18    
19     3. I had an email from Eric Raymond about problems translating some of PCRE's
20        man pages to HTML (despite the fact that I distribute HTML pages, some
21        people do their own conversions for various reasons). The problems
22        concerned the use of low-level troff macros .br and .in. I have therefore
23        removed all such uses from the man pages (some were redundant, some could
24        be replaced by .nf/.fi pairs). The 132html script that I use to generate
25        HTML has been updated to handle .nf/.fi and to complain if it encounters
26        .br or .in.
27    
28     4. Updated comments in configure.ac that get placed in config.h.in and also
29        arranged for config.h to be included in the distribution, with the name
30        config.h.generic, for the benefit of those who have to compile without
31        Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
32    
33     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
34        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
35        makevp.bat for the current PCRE, using the additional files !compile.txt,
36        !linklib.txt, and pcregexp.pas.
37    
38     6. A Windows user reported a minor discrepancy with test 2, which turned out
39        to be caused by a trailing space on an input line that had got lost in his
40        copy. The trailing space was an accident, so I've just removed it.
41    
42     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
43        that is needed.
44    
45     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
46        as "const" (a) because they are and (b) because it helps the PHP
47        maintainers who have recently made a script to detect big data structures
48        in the php code that should be moved to the .rodata section. I remembered
49        to update Builducptable as well, so it won't revert if ucptable.h is ever
50        re-created.
51    
52     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
53        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
54        order to be able to cut out the UTF-8 tables in the latter when UTF-8
55        support is not required. This saves 1.5-2K of code, which is important in
56        some applications.
57    
58        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
59        so as not to refer to the tables, even though these functions will never be
60        called when UTF-8 support is disabled. Otherwise there are problems with a
61        shared library.
62    
63    10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
64    
65        (a) It was defining its arguments as char * instead of void *.
66    
67        (b) It was assuming that all moves were upwards in memory; this was true
68            a long time ago when I wrote it, but is no longer the case.
69    
70        The emulated memove() is provided for those environments that have neither
71        memmove() nor bcopy(). I didn't think anyone used it these days, but that
72        is clearly not the case, as these two bugs were recently reported.
73    
74    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
75        and Detrail to create the HTML documentation, the .txt form of the man
76        pages, and it removes trailing spaces from listed files. It also creates
77        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
78        case, it wraps all the #defines with #ifndefs. This script should be run
79        before "make dist".
80    
81    12. Fixed two fairly obscure bugs concerned with quantified caseless matching
82        with Unicode property support.
83    
84        (a) For a maximizing quantifier, if the two different cases of the
85            character were of different lengths in their UTF-8 codings (there are
86            some cases like this - I found 11), and the matching function had to
87            back up over a mixture of the two cases, it incorrectly assumed they
88            were both the same length.
89    
90        (b) When PCRE was configured to use the heap rather than the stack for
91            recursion during matching, it was not correctly preserving the data for
92            the other case of a UTF-8 character when checking ahead for a match
93            while processing a minimizing repeat. If the check also involved
94            matching a wide character, but failed, corruption could cause an
95            erroneous result when trying to check for a repeat of the original
96            character.
97    
98    13. Some tidying changes to the testing mechanism:
99    
100        (a) The RunTest script now detects the internal link size and whether there
101            is UTF-8 and UCP support by running ./pcretest -C instead of relying on
102            values substituted by "configure". (The RunGrepTest script already did
103            this for UTF-8.) The configure.ac script no longer substitutes the
104            relevant variables.
105    
106        (b) The debugging options /B and /D in pcretest show the compiled bytecode
107            with length and offset values. This means that the output is different
108            for different internal link sizes. Test 2 is skipped for link sizes
109            other than 2 because of this, bypassing the problem. Unfortunately,
110            there was also a test in test 3 (the locale tests) that used /B and
111            failed for link sizes other than 2. Rather than cut the whole test out,
112            I have added a new /Z option to pcretest that replaces the length and
113            offset values with spaces. This is now used to make test 3 independent
114            of link size. (Test 2 will be tidied up later.)
115    
116    14. If erroroffset was passed as NULL to pcre_compile, it provoked a
117        segmentation fault instead of returning the appropriate error message.
118    
119    
120    Version 7.0 19-Dec-06
121    ---------------------
122    
123     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
124        moving to gcc 4.1.1.
125    
126     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
127        sys/time.h, which is documented as needed for this function. It doesn't
128        seem to matter on Linux, but it showed up on some releases of OS X.
129    
130     3. It seems that there are systems where bytes whose values are greater than
131        127 match isprint() in the "C" locale. The "C" locale should be the
132        default when a C program starts up. In most systems, only ASCII printing
133        characters match isprint(). This difference caused the output from pcretest
134        to vary, making some of the tests fail. I have changed pcretest so that:
135    
136        (a) When it is outputting text in the compiled version of a pattern, bytes
137            other than 32-126 are always shown as hex escapes.
138    
139        (b) When it is outputting text that is a matched part of a subject string,
140            it does the same, unless a different locale has been set for the match
141            (using the /L modifier). In this case, it uses isprint() to decide.
142    
143     4. Fixed a major bug that caused incorrect computation of the amount of memory
144        required for a compiled pattern when options that changed within the
145        pattern affected the logic of the preliminary scan that determines the
146        length. The relevant options are -x, and -i in UTF-8 mode. The result was
147        that the computed length was too small. The symptoms of this bug were
148        either the PCRE error "internal error: code overflow" from pcre_compile(),
149        or a glibc crash with a message such as "pcretest: free(): invalid next
150        size (fast)". Examples of patterns that provoked this bug (shown in
151        pcretest format) are:
152    
153          /(?-x: )/x
154          /(?x)(?-x: \s*#\s*)/
155          /((?i)[\x{c0}])/8
156          /(?i:[\x{c0}])/8
157    
158        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
159        is now done differently.
160    
161     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
162        wrapper classes; (b) implement a new function in the C++ scanner that is
163        more efficient than the old way of doing things because it avoids levels of
164        recursion in the regex matching; (c) add a paragraph to the documentation
165        for the FullMatch() function.
166    
167     6. The escape sequence \n was being treated as whatever was defined as
168        "newline". Not only was this contrary to the documentation, which states
169        that \n is character 10 (hex 0A), but it also went horribly wrong when
170        "newline" was defined as CRLF. This has been fixed.
171    
172     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
173        was being set to -1 for the "end of line" case (supposedly a value that no
174        character can have). Though this value is never used (the check for end of
175        line is "zero bytes in current character"), it caused compiler complaints.
176        I've changed it to 0xffffffff.
177    
178     8. In pcre_version.c, the version string was being built by a sequence of
179        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
180        string (as it is for production releases) called a macro with an empty
181        argument. The C standard says the result of this is undefined. The gcc
182        compiler treats it as an empty string (which was what was wanted) but it is
183        reported that Visual C gives an error. The source has been hacked around to
184        avoid this problem.
185    
186     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
187        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
188        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
189        of them did).
190    
191    10. Originally, pcretest opened its input and output without "b"; then I was
192        told that "b" was needed in some environments, so it was added for release
193        5.0 to both the input and output. (It makes no difference on Unix-like
194        systems.) Later I was told that it is wrong for the input on Windows. I've
195        now abstracted the modes into two macros, to make it easier to fiddle with
196        them, and removed "b" from the input mode under Windows.
197    
198    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
199    
200    12. Added -help and --help to pcretest as an official way of being reminded
201        of the options.
202    
203    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
204        and pcrecpp.cc because they annoy compilers at high warning levels.
205    
206    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
207    
208    15. Fixed an occurrence of == in configure.ac that should have been = (shell
209        scripts are not C programs :-) and which was not noticed because it works
210        on Linux.
211    
212    16. pcretest is supposed to handle any length of pattern and data line (as one
213        line or as a continued sequence of lines) by extending its input buffer if
214        necessary. This feature was broken for very long pattern lines, leading to
215        a string of junk being passed to pcre_compile() if the pattern was longer
216        than about 50K.
217    
218    17. I have done a major re-factoring of the way pcre_compile() computes the
219        amount of memory needed for a compiled pattern. Previously, there was code
220        that made a preliminary scan of the pattern in order to do this. That was
221        OK when PCRE was new, but as the facilities have expanded, it has become
222        harder and harder to keep it in step with the real compile phase, and there
223        have been a number of bugs (see for example, 4 above). I have now found a
224        cunning way of running the real compile function in a "fake" mode that
225        enables it to compute how much memory it would need, while actually only
226        ever using a few hundred bytes of working memory and without too many
227        tests of the mode. This should make future maintenance and development
228        easier. A side effect of this work is that the limit of 200 on the nesting
229        depth of parentheses has been removed (though this was never a serious
230        limitation, I suspect). However, there is a downside: pcre_compile() now
231        runs more slowly than before (30% or more, depending on the pattern). I
232        hope this isn't a big issue. There is no effect on runtime performance.
233    
234    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
235        newline (only possible for the last line of a file) and it was a
236        pattern that set a locale (followed by /Lsomething), pcretest crashed.
237    
238    19. Added additional timing features to pcretest. (1) The -tm option now times
239        matching only, not compiling. (2) Both -t and -tm can be followed, as a
240        separate command line item, by a number that specifies the number of
241        repeats to use when timing. The default is 50000; this gives better
242        precision, but takes uncomfortably long for very large patterns.
243    
244    20. Extended pcre_study() to be more clever in cases where a branch of a
245        subpattern has no definite first character. For example, (a*|b*)[cd] would
246        previously give no result from pcre_study(). Now it recognizes that the
247        first character must be a, b, c, or d.
248    
249    21. There was an incorrect error "recursive call could loop indefinitely" if
250        a subpattern (or the entire pattern) that was being tested for matching an
251        empty string contained only one non-empty item after a nested subpattern.
252        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
253        incorrectly, because the \d was being skipped in the check.
254    
255    22. The pcretest program now has a new pattern option /B and a command line
256        option -b, which is equivalent to adding /B to every pattern. This causes
257        it to show the compiled bytecode, without the additional information that
258        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
259        is the same as /B/I).
260    
261    23. A new optimization is now able automatically to treat some sequences such
262        as a*b as a*+b. More specifically, if something simple (such as a character
263        or a simple class like \d) has an unlimited quantifier, and is followed by
264        something that cannot possibly match the quantified thing, the quantifier
265        is automatically "possessified".
266    
267    24. A recursive reference to a subpattern whose number was greater than 39
268        went wrong under certain circumstances in UTF-8 mode. This bug could also
269        have affected the operation of pcre_study().
270    
271    25. Realized that a little bit of performance could be had by replacing
272        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
273    
274    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
275    
276    27. Possessive quantifiers such as a++ were previously implemented by turning
277        them into atomic groups such as ($>a+). Now they have their own opcodes,
278        which improves performance. This includes the automatically created ones
279        from 23 above.
280    
281    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
282        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
283        the first matched character to be a colon. This applied both to named and
284        numbered groups.
285    
286    29. The ucpinternal.h header file was missing its idempotency #ifdef.
287    
288    30. I was sent a "project" file called libpcre.a.dev which I understand makes
289        building PCRE on Windows easier, so I have included it in the distribution.
290    
291    31. There is now a check in pcretest against a ridiculously large number being
292        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
293        loop, the loop is abandoned.
294    
295    32. Forward references to subpatterns in conditions such as (?(2)...) where
296        subpattern 2 is defined later cause pcre_compile() to search forwards in
297        the pattern for the relevant set of parentheses. This search went wrong
298        when there were unescaped parentheses in a character class, parentheses
299        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
300    
301    33. "Subroutine" calls and backreferences were previously restricted to
302        referencing subpatterns earlier in the regex. This restriction has now
303        been removed.
304    
305    34. Added a number of extra features that are going to be in Perl 5.10. On the
306        whole, these are just syntactic alternatives for features that PCRE had
307        previously implemented using the Python syntax or my own invention. The
308        other formats are all retained for compatibility.
309    
310        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
311            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
312            also .NET compatible.
313    
314        (b) A recursion or subroutine call to a named group can now be defined as
315            (?&name) as well as (?P>name).
316    
317        (c) A backreference to a named group can now be defined as \k<name> or
318            \k'name' as well as (?P=name). The new forms, as well as being in Perl
319            5.10, are also .NET compatible.
320    
321        (d) A conditional reference to a named group can now use the syntax
322            (?(<name>) or (?('name') as well as (?(name).
323    
324        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
325            groups (named and numbered) that are never evaluated inline, but can be
326            called as "subroutines" from elsewhere. In effect, the DEFINE condition
327            is always false. There may be only one alternative in such a group.
328    
329        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
330            as the simple (?(R). The condition is true only if the most recent
331            recursion is that of the given number or name. It does not search out
332            through the entire recursion stack.
333    
334        (g) The escape \gN or \g{N} has been added, where N is a positive or
335            negative number, specifying an absolute or relative reference.
336    
337    35. Tidied to get rid of some further signed/unsigned compiler warnings and
338        some "unreachable code" warnings.
339    
340    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
341        things, this adds five new scripts.
342    
343    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
344        There were also incompatibilities regarding the handling of \Q..\E inside
345        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
346        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
347    
348    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
349        matches an empty string, and forcibly breaks the loop. There were bugs in
350        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
351        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
352        separate and independent bugs (that affected different cases) have been
353        fixed.
354    
355    39. Refactored the code to abolish the use of different opcodes for small
356        capturing bracket numbers. This is a tidy that I avoided doing when I
357        removed the limit on the number of capturing brackets for 3.5 back in 2001.
358        The new approach is not only tidier, it makes it possible to reduce the
359        memory needed to fix the previous bug (38).
360    
361    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
362        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
363        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
364        mode.
365    
366    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
367        report.
368    
369    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
370        copy construction and assignment in the C++ wrapper.
371    
372    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
373        couple of bugs that could have given wrong results in the "--newline=crlf"
374        case.
375    
376    44. Added a number of casts and did some reorganization of signed/unsigned int
377        variables following suggestions from Dair Grant. Also renamed the variable
378        "this" as "item" because it is a C++ keyword.
379    
380    45. Arranged for dftables to add
381    
382          #include "pcre_internal.h"
383    
384        to pcre_chartables.c because without it, gcc 4.x may remove the array
385        definition from the final binary if PCRE is built into a static library and
386        dead code stripping is activated.
387    
388    46. For an unanchored pattern, if a match attempt fails at the start of a
389        newline sequence, and the newline setting is CRLF or ANY, and the next two
390        characters are CRLF, advance by two characters instead of one.
391    
392    
393    Version 6.7 04-Jul-06
394    ---------------------
395    
396     1. In order to handle tests when input lines are enormously long, pcretest has
397        been re-factored so that it automatically extends its buffers when
398        necessary. The code is crude, but this _is_ just a test program. The
399        default size has been increased from 32K to 50K.
400    
401     2. The code in pcre_study() was using the value of the re argument before
402        testing it for NULL. (Of course, in any sensible call of the function, it
403        won't be NULL.)
404    
405     3. The memmove() emulation function in pcre_internal.h, which is used on
406        systems that lack both memmove() and bcopy() - that is, hardly ever -
407        was missing a "static" storage class specifier.
408    
409     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
410        containing an extended class (one that cannot be represented by a bitmap
411        because it contains high-valued characters or Unicode property items, e.g.
412        [\pZ]). Almost always one would set UTF-8 mode when processing such a
413        pattern, but PCRE should not loop if you do not (it no longer does).
414        [Detail: two cases were found: (a) a repeated subpattern containing an
415        extended class; (b) a recursive reference to a subpattern that followed a
416        previous extended class. It wasn't skipping over the extended class
417        correctly when UTF-8 mode was not set.]
418    
419     5. A negated single-character class was not being recognized as fixed-length
420        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
421        compile error "lookbehind assertion is not fixed length".
422    
423     6. The RunPerlTest auxiliary script was showing an unexpected difference
424        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
425        write a Perl script that can interpret lines of an input file either as
426        byte characters or as UTF-8, which is what "perltest" was being required to
427        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
428        can't do is switch easily at run time between having the "use utf8;" pragma
429        or not. In the end, I fudged it by using the RunPerlTest script to insert
430        "use utf8;" explicitly for the UTF-8 tests.
431    
432     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
433        the end of the subject string, contrary to the documentation and to what
434        Perl does. This was true of both matching functions. Now it matches only at
435        the start of the subject and immediately after *internal* newlines.
436    
437     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
438        a pointer to an int instead of a pointer to an unsigned long int. This
439        caused problems on 64-bit systems.
440    
441     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
442        instance of the 'standard' template library not being so standard".
443    
444    10. There was no check on the number of named subpatterns nor the maximum
445        length of a subpattern name. The product of these values is used to compute
446        the size of the memory block for a compiled pattern. By supplying a very
447        long subpattern name and a large number of named subpatterns, the size
448        computation could be caused to overflow. This is now prevented by limiting
449        the length of names to 32 characters, and the number of named subpatterns
450        to 10,000.
451    
452    11. Subpatterns that are repeated with specific counts have to be replicated in
453        the compiled pattern. The size of memory for this was computed from the
454        length of the subpattern and the repeat count. The latter is limited to
455        65535, but there was no limit on the former, meaning that integer overflow
456        could in principle occur. The compiled length of a repeated subpattern is
457        now limited to 30,000 bytes in order to prevent this.
458    
459    12. Added the optional facility to have named substrings with the same name.
460    
461    13. Added the ability to use a named substring as a condition, using the
462        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
463        are numbers (not recommended). Forward references are permitted.
464    
465    14. Added forward references in named backreferences (if you see what I mean).
466    
467    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
468        pattern could run off the end of the subject. For example, the pattern
469        "(?s)(.{1,5})"8 did this with the subject "ab".
470    
471    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
472        PCRE_CASELESS was set when matching characters that were quantified with ?
473        or *.
474    
475    17. A character class other than a single negated character that had a minimum
476        but no maximum quantifier - for example [ab]{6,} - was not handled
477        correctly by pce_dfa_exec(). It would match only one character.
478    
479    18. A valid (though odd) pattern that looked like a POSIX character
480        class but used an invalid character after [ (for example [[,abc,]]) caused
481        pcre_compile() to give the error "Failed: internal error: code overflow" or
482        in some cases to crash with a glibc free() error. This could even happen if
483        the pattern terminated after [[ but there just happened to be a sequence of
484        letters, a binary zero, and a closing ] in the memory that followed.
485    
486    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
487        over the years. Originally (before any Unicode support), just the bottom 8
488        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
489        output from "man perlunicode" includes this:
490    
491          The regular expression compiler produces polymorphic opcodes.  That
492          is, the pattern adapts to the data and automatically switches to
493          the Unicode character scheme when presented with Unicode data--or
494          instead uses a traditional byte scheme when presented with byte
495          data.
496    
497        Sadly, a wide octal escape does not cause a switch, and in a string with
498        no other multibyte characters, these octal escapes are treated as before.
499        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
500        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
501        Unicode string.
502    
503        I have not perpetrated such confusion in PCRE. Up till now, it took just
504        the bottom 8 bits, as in old Perl. I have now made octal escapes with
505        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
506        translate to the appropriate multibyte character.
507    
508    29. Applied some refactoring to reduce the number of warnings from Microsoft
509        and Borland compilers. This has included removing the fudge introduced
510        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
511        a warning about an unused variable.
512    
513    21. PCRE has not included VT (character 0x0b) in the set of whitespace
514        characters since release 4.0, because Perl (from release 5.004) does not.
515        [Or at least, is documented not to: some releases seem to be in conflict
516        with the documentation.] However, when a pattern was studied with
517        pcre_study() and all its branches started with \s, PCRE still included VT
518        as a possible starting character. Of course, this did no harm; it just
519        caused an unnecessary match attempt.
520    
521    22. Removed a now-redundant internal flag bit that recorded the fact that case
522        dependency changed within the pattern. This was once needed for "required
523        byte" processing, but is no longer used. This recovers a now-scarce options
524        bit. Also moved the least significant internal flag bit to the most-
525        significant bit of the word, which was not previously used (hangover from
526        the days when it was an int rather than a uint) to free up another bit for
527        the future.
528    
529    23. Added support for CRLF line endings as well as CR and LF. As well as the
530        default being selectable at build time, it can now be changed at runtime
531        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
532        specify that it is scanning data with non-default line endings.
533    
534    24. Changed the definition of CXXLINK to make it agree with the definition of
535        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
536    
537    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
538        recursions. This makes a big different to stack usage for some patterns.
539    
540    26. If a subpattern containing a named recursion or subroutine reference such
541        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
542        the space required for the compiled pattern went wrong and gave too small a
543        value. Depending on the environment, this could lead to "Failed: internal
544        error: code overflow at offset 49" or "glibc detected double free or
545        corruption" errors.
546    
547    27. Applied patches from Google (a) to support the new newline modes and (b) to
548        advance over multibyte UTF-8 characters in GlobalReplace.
549    
550    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
551        difference for some implementation of PCRE in some Windows version.
552    
553    29. Added some extra testing facilities to pcretest:
554    
555        \q<number>   in a data line sets the "match limit" value
556        \Q<number>   in a data line sets the "match recursion limt" value
557        -S <number>  sets the stack size, where <number> is in megabytes
558    
559        The -S option isn't available for Windows.
560    
561    
562    Version 6.6 06-Feb-06
563    ---------------------
564    
565     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
566        in pcreposix.h. I have copied the definition from pcre.h.
567    
568     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
569        because pcre.h is no longer a built file.
570    
571     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
572        not normally included in the compiled code.
573    
574    
575    Version 6.5 01-Feb-06
576    ---------------------
577    
578     1. When using the partial match feature with pcre_dfa_exec(), it was not
579        anchoring the second and subsequent partial matches at the new starting
580        point. This could lead to incorrect results. For example, with the pattern
581        /1234/, partially matching against "123" and then "a4" gave a match.
582    
583     2. Changes to pcregrep:
584    
585        (a) All non-match returns from pcre_exec() were being treated as failures
586            to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
587            error message is output. Some extra information is given for the
588            PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
589            probably the only errors that are likely to be caused by users (by
590            specifying a regex that has nested indefinite repeats, for instance).
591            If there are more than 20 of these errors, pcregrep is abandoned.
592    
593        (b) A binary zero was treated as data while matching, but terminated the
594            output line if it was written out. This has been fixed: binary zeroes
595            are now no different to any other data bytes.
596    
597        (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
598            used to set a locale for matching. The --locale=xxxx long option has
599            been added (no short equivalent) to specify a locale explicitly on the
600            pcregrep command, overriding the environment variables.
601    
602        (d) When -B was used with -n, some line numbers in the output were one less
603            than they should have been.
604    
605        (e) Added the -o (--only-matching) option.
606    
607        (f) If -A or -C was used with -c (count only), some lines of context were
608            accidentally printed for the final match.
609    
610        (g) Added the -H (--with-filename) option.
611    
612        (h) The combination of options -rh failed to suppress file names for files
613            that were found from directory arguments.
614    
615        (i) Added the -D (--devices) and -d (--directories) options.
616    
617        (j) Added the -F (--fixed-strings) option.
618    
619        (k) Allow "-" to be used as a file name for -f as well as for a data file.
620    
621        (l) Added the --colo(u)r option.
622    
623        (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
624            is not present by default.
625    
626     3. A nasty bug was discovered in the handling of recursive patterns, that is,
627        items such as (?R) or (?1), when the recursion could match a number of
628        alternatives. If it matched one of the alternatives, but subsequently,
629        outside the recursion, there was a failure, the code tried to back up into
630        the recursion. However, because of the way PCRE is implemented, this is not
631        possible, and the result was an incorrect result from the match.
632    
633        In order to prevent this happening, the specification of recursion has
634        been changed so that all such subpatterns are automatically treated as
635        atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
636    
637     4. I had overlooked the fact that, in some locales, there are characters for
638        which isalpha() is true but neither isupper() nor islower() are true. In
639        the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
640        and ordfeminine) are like this. This affected the treatment of \w and \W
641        when they appeared in character classes, but not when they appeared outside
642        a character class. The bit map for "word" characters is now created
643        separately from the results of isalnum() instead of just taking it from the
644        upper, lower, and digit maps. (Plus the underscore character, of course.)
645    
646     5. The above bug also affected the handling of POSIX character classes such as
647        [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
648        permanent tables. Instead, the bit maps for such a class were previously
649        created as the appropriate unions of the upper, lower, and digit bitmaps.
650        Now they are created by subtraction from the [[:word:]] class, which has
651        its own bitmap.
652    
653     6. The [[:blank:]] character class matches horizontal, but not vertical space.
654        It is created by subtracting the vertical space characters (\x09, \x0a,
655        \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
656        subtraction was done in the overall bitmap for a character class, meaning
657        that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
658        be recognized. This bug has been fixed.
659    
660     7. Patches from the folks at Google:
661    
662          (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
663          real life, but is still worth protecting against".
664    
665          (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
666          regular expressions".
667    
668          (c) pcre_scanner.cc: avoid use of std::count() because not all systems
669          have it.
670    
671          (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
672          "configure" and the latter not, in order to fix a problem somebody had
673          with compiling the Arg class on HP-UX.
674    
675          (e) Improve the error-handling of the C++ wrapper a little bit.
676    
677          (f) New tests for checking recursion limiting.
678    
679     8. The pcre_memmove() function, which is used only if the environment does not
680        have a standard memmove() function (and is therefore rarely compiled),
681        contained two bugs: (a) use of int instead of size_t, and (b) it was not
682        returning a result (though PCRE never actually uses the result).
683    
684     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
685        large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
686        returned instead of calling malloc() with an overflowing number that would
687        most likely cause subsequent chaos.
688    
689    10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
690    
691    11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
692        with this option is matched, the nmatch and pmatch options of regexec() are
693        ignored.
694    
695    12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
696        provided in case anyone wants to the the POSIX interface with UTF-8
697        strings.
698    
699    13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
700        C++ linking (needed for some HP-UX environments).
701    
702    14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
703        (unused parameter) and in the pcre_printint() function (omitted "default"
704        switch label when the default is to do nothing).
705    
706    15. Added some code to make it possible, when PCRE is compiled as a C++
707        library, to replace subject pointers for pcre_exec() with a smart pointer
708        class, thus making it possible to process discontinuous strings.
709    
710    16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
711        much the same function. They were added by different people who were trying
712        to make PCRE easy to compile on non-Unix systems. It has been suggested
713        that PCRE_EXPORT be abolished now that there is more automatic apparatus
714        for compiling on Windows systems. I have therefore replaced it with
715        PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
716        defaults to "extern" for C or "extern C" for C++, which works fine on
717        Unix-like systems. It is now possible to override the value of PCRE_DATA_
718        SCOPE with something explicit in config.h. In addition:
719    
720        (a) pcreposix.h still had just "extern" instead of either of these macros;
721            I have replaced it with PCRE_DATA_SCOPE.
722    
723        (b) Functions such as _pcre_xclass(), which are internal to the library,
724            but external in the C sense, all had PCRE_EXPORT in their definitions.
725            This is apparently wrong for the Windows case, so I have removed it.
726            (It makes no difference on Unix-like systems.)
727    
728    17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
729        of recursive calls to match(). This is different to MATCH_LIMIT because
730        that limits the total number of calls to match(), not all of which increase
731        the depth of recursion. Limiting the recursion depth limits the amount of
732        stack (or heap if NO_RECURSE is set) that is used. The default can be set
733        when PCRE is compiled, and changed at run time. A patch from Google adds
734        this functionality to the C++ interface.
735    
736    18. Changes to the handling of Unicode character properties:
737    
738        (a) Updated the table to Unicode 4.1.0.
739    
740        (b) Recognize characters that are not in the table as "Cn" (undefined).
741    
742        (c) I revised the way the table is implemented to a much improved format
743            which includes recognition of ranges. It now supports the ranges that
744            are defined in UnicodeData.txt, and it also amalgamates other
745            characters into ranges. This has reduced the number of entries in the
746            table from around 16,000 to around 3,000, thus reducing its size
747            considerably. I realized I did not need to use a tree structure after
748            all - a binary chop search is just as efficient. Having reduced the
749            number of entries, I extended their size from 6 bytes to 8 bytes to
750            allow for more data.
751    
752        (d) Added support for Unicode script names via properties such as \p{Han}.
753    
754    19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
755        matching that character.
756    
757    20. When matching a repeated Unicode property with a minimum greater than zero,
758        (for example \pL{2,}), PCRE could look past the end of the subject if it
759        reached it while seeking the minimum number of characters. This could
760        happen only if some of the characters were more than one byte long, because
761        there is a check for at least the minimum number of bytes.
762    
763    21. Refactored the implementation of \p and \P so as to be more general, to
764        allow for more different types of property in future. This has changed the
765        compiled form incompatibly. Anybody with saved compiled patterns that use
766        \p or \P will have to recompile them.
767    
768    22. Added "Any" and "L&" to the supported property types.
769    
770    23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
771        but give a compile time error if the value is greater than 0xff.
772    
773    24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
774        accidentally not being installed or uninstalled.
775    
776    25. The pcre.h file was built from pcre.h.in, but the only changes that were
777        made were to insert the current release number. This seemed silly, because
778        it made things harder for people building PCRE on systems that don't run
779        "configure". I have turned pcre.h into a distributed file, no longer built
780        by "configure", with the version identification directly included. There is
781        no longer a pcre.h.in file.
782    
783        However, this change necessitated a change to the pcre-config script as
784        well. It is built from pcre-config.in, and one of the substitutions was the
785        release number. I have updated configure.ac so that ./configure now finds
786        the release number by grepping pcre.h.
787    
788    26. Added the ability to run the tests under valgrind.
789    
790    
791    Version 6.4 05-Sep-05
792    ---------------------
793    
794     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
795        "--" to be printed when multiple files were scanned, even when none of the
796        -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
797        consider it to be a bug, and have restored the previous behaviour.
798    
799     2. A couple of code tidies to get rid of compiler warnings.
800    
801     3. The pcretest program used to cheat by referring to symbols in the library
802        whose names begin with _pcre_. These are internal symbols that are not
803        really supposed to be visible externally, and in some environments it is
804        possible to suppress them. The cheating is now confined to including
805        certain files from the library's source, which is a bit cleaner.
806    
807     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
808        file's purpose clearer.
809    
810     5. Reorganized pcre_ucp_findchar().
811    
812    
813    Version 6.3 15-Aug-05
814    ---------------------
815    
816     1. The file libpcre.pc.in did not have general read permission in the tarball.
817    
818     2. There were some problems when building without C++ support:
819    
820        (a) If C++ support was not built, "make install" and "make test" still
821            tried to test it.
822    
823        (b) There were problems when the value of CXX was explicitly set. Some
824            changes have been made to try to fix these, and ...
825    
826        (c) --disable-cpp can now be used to explicitly disable C++ support.
827    
828        (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
829            backslash in a target when C++ was disabled. This confuses some
830            versions of "make", apparently. Using an intermediate variable solves
831            this. (Same for CPP_LOBJ.)
832    
833     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
834        (non-Windows) now includes $(CFLAGS) because these flags are sometimes
835        necessary on certain architectures.
836    
837     4. Added a setting of -export-symbols-regex to the link command to remove
838        those symbols that are exported in the C sense, but actually are local
839        within the library, and not documented. Their names all begin with
840        "_pcre_". This is not a perfect job, because (a) we have to except some
841        symbols that pcretest ("illegally") uses, and (b) the facility isn't always
842        available (and never for static libraries). I have made a note to try to
843        find a way round (a) in the future.
844    
845    
846    Version 6.2 01-Aug-05
847    ---------------------
848    
849     1. There was no test for integer overflow of quantifier values. A construction
850        such as {1111111111111111} would give undefined results. What is worse, if
851        a minimum quantifier for a parenthesized subpattern overflowed and became
852        negative, the calculation of the memory size went wrong. This could have
853        led to memory overwriting.
854    
855     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
856    
857     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
858        operating environments where this matters.
859    
860     4. Applied Giuseppe Maxia's patch to add additional features for controlling
861        PCRE options from within the C++ wrapper.
862    
863     5. Named capturing subpatterns were not being correctly counted when a pattern
864        was compiled. This caused two problems: (a) If there were more than 100
865        such subpatterns, the calculation of the memory needed for the whole
866        compiled pattern went wrong, leading to an overflow error. (b) Numerical
867        back references of the form \12, where the number was greater than 9, were
868        not recognized as back references, even though there were sufficient
869        previous subpatterns.
870    
871     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
872        versions of gcc, e.g. 2.95.4.
873    
874    
875    Version 6.1 21-Jun-05
876    ---------------------
877    
878     1. There was one reference to the variable "posix" in pcretest.c that was not
879        surrounded by "#if !defined NOPOSIX".
880    
881     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
882        the cross-check on the old pcre_info() function, for the benefit of the
883        cut-down version of PCRE that is currently imported into Exim.
884    
885     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
886        allocation error. I've done the easy fix, which wastes 2 bytes for sensible
887        patterns that start (?i) but I don't think that matters. The use of (?i) is
888        just an example; this all applies to the other options as well.
889    
890     4. Since libtool seems to echo the compile commands it is issuing, the output
891        from "make" can be reduced a bit by putting "@" in front of each libtool
892        compile command.
893    
894     5. Patch from the folks at Google for configure.in to be a bit more thorough
895        in checking for a suitable C++ installation before trying to compile the
896        C++ stuff. This should fix a reported problem when a compiler was present,
897        but no suitable headers.
898    
899     6. The man pages all had just "PCRE" as their title. I have changed them to
900        be the relevant file name. I have also arranged that these names are
901        retained in the file doc/pcre.txt, which is a concatenation in text format
902        of all the man pages except the little individual ones for each function.
903    
904     7. The NON-UNIX-USE file had not been updated for the different set of source
905        files that come with release 6. I also added a few comments about the C++
906        wrapper.
907    
908    
909    Version 6.0 07-Jun-05
910    ---------------------
911    
912     1. Some minor internal re-organization to help with my DFA experiments.
913    
914     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
915        didn't matter for the library itself when fully configured, but did matter
916        when compiling without UCP support, or within Exim, where the ucp files are
917        not imported.
918    
919     3. Refactoring of the library code to split up the various functions into
920        different source modules. The addition of the new DFA matching code (see
921        below) to a single monolithic source would have made it really too
922        unwieldy, quite apart from causing all the code to be include in a
923        statically linked application, when only some functions are used. This is
924        relevant even without the DFA addition now that patterns can be compiled in
925        one application and matched in another.
926    
927        The downside of splitting up is that there have to be some external
928        functions and data tables that are used internally in different modules of
929        the library but which are not part of the API. These have all had their
930        names changed to start with "_pcre_" so that they are unlikely to clash
931        with other external names.
932    
933     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
934        a different (DFA) algorithm. Although it is slower than the original
935        function, it does have some advantages for certain types of matching
936        problem.
937    
938     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
939        including restarting after a partial match.
940    
941     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
942        defined when compiling for Windows was sent to me. I have put it into the
943        code, though I have no means of testing or verifying it.
944    
945     7. Added the pcre_refcount() auxiliary function.
946    
947     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
948        match before or at the first newline in the subject string. In pcretest,
949        the /f option on a pattern can be used to set this.
950    
951     9. A repeated \w when used in UTF-8 mode with characters greater than 256
952        would behave wrongly. This has been present in PCRE since release 4.0.
953    
954    10. A number of changes to the pcregrep command:
955    
956        (a) Refactored how -x works; insert ^(...)$ instead of setting
957            PCRE_ANCHORED and checking the length, in preparation for adding
958            something similar for -w.
959    
960        (b) Added the -w (match as a word) option.
961    
962        (c) Refactored the way lines are read and buffered so as to have more
963            than one at a time available.
964    
965        (d) Implemented a pcregrep test script.
966    
967        (e) Added the -M (multiline match) option. This allows patterns to match
968            over several lines of the subject. The buffering ensures that at least
969            8K, or the rest of the document (whichever is the shorter) is available
970            for matching (and similarly the previous 8K for lookbehind assertions).
971    
972        (f) Changed the --help output so that it now says
973    
974              -w, --word-regex(p)
975    
976            instead of two lines, one with "regex" and the other with "regexp"
977            because that confused at least one person since the short forms are the
978            same. (This required a bit of code, as the output is generated
979            automatically from a table. It wasn't just a text change.)
980    
981        (g) -- can be used to terminate pcregrep options if the next thing isn't an
982            option but starts with a hyphen. Could be a pattern or a path name
983            starting with a hyphen, for instance.
984    
985        (h) "-" can be given as a file name to represent stdin.
986    
987        (i) When file names are being printed, "(standard input)" is used for
988            the standard input, for compatibility with GNU grep. Previously
989            "<stdin>" was used.
990    
991        (j) The option --label=xxx can be used to supply a name to be used for
992            stdin when file names are being printed. There is no short form.
993    
994        (k) Re-factored the options decoding logic because we are going to add
995            two more options that take data. Such options can now be given in four
996            different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
997    
998        (l) Added the -A, -B, and -C options for requesting that lines of context
999            around matches be printed.
1000    
1001        (m) Added the -L option to print the names of files that do not contain
1002            any matching lines, that is, the complement of -l.
1003    
1004        (n) The return code is 2 if any file cannot be opened, but pcregrep does
1005            continue to scan other files.
1006    
1007        (o) The -s option was incorrectly implemented. For compatibility with other
1008            greps, it now suppresses the error message for a non-existent or non-
1009            accessible file (but not the return code). There is a new option called
1010            -q that suppresses the output of matching lines, which was what -s was
1011            previously doing.
1012    
1013        (p) Added --include and --exclude options to specify files for inclusion
1014            and exclusion when recursing.
1015    
1016    11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1017        Hopefully, it now does.
1018    
1019    12. Missing cast in pcre_study().
1020    
1021    13. Added an "uninstall" target to the makefile.
1022    
1023    14. Replaced "extern" in the function prototypes in Makefile.in with
1024        "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1025        world, but is set differently for Windows.
1026    
1027    15. Added a second compiling function called pcre_compile2(). The only
1028        difference is that it has an extra argument, which is a pointer to an
1029        integer error code. When there is a compile-time failure, this is set
1030        non-zero, in addition to the error test pointer being set to point to an
1031        error message. The new argument may be NULL if no error number is required
1032        (but then you may as well call pcre_compile(), which is now just a
1033        wrapper). This facility is provided because some applications need a
1034        numeric error indication, but it has also enabled me to tidy up the way
1035        compile-time errors are handled in the POSIX wrapper.
1036    
1037    16. Added VPATH=.libs to the makefile; this should help when building with one
1038        prefix path and installing with another. (Or so I'm told by someone who
1039        knows more about this stuff than I do.)
1040    
1041    17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1042        passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1043        match everything, including newlines. This is not POSIX-compatible, but
1044        somebody wanted the feature. From pcretest it can be activated by using
1045        both the P and the s flags.
1046    
1047    18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1048    
1049    19. libpcre.pc was being incorrectly installed as executable.
1050    
1051    20. A couple of places in pcretest check for end-of-line by looking for '\n';
1052        it now also looks for '\r' so that it will work unmodified on Windows.
1053    
1054    21. Added Google's contributed C++ wrapper to the distribution.
1055    
1056    22. Added some untidy missing memory free() calls in pcretest, to keep
1057        Electric Fence happy when testing.
1058    
1059    
1060    
1061  Version 5.0 13-Sep-04  Version 5.0 13-Sep-04
1062  ---------------------  ---------------------
1063    

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