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revision 91 by nigel, Sat Feb 24 21:41:34 2007 UTC revision 141 by ph10, Fri Mar 30 15:46:27 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
36        makevp_c.txt, makevp_l.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    15. In multiline mode when the newline sequence was set to "any", the pattern
120        ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
121        This doesn't seem right; it now treats the CRLF combination as the line
122        ending, and so does not match in that case. It's only a pattern such as ^$
123        that would hit this one: something like ^ABC$ would have failed after \r
124        and then tried again after \r\n.
125    
126    16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
127        in an attempt to make files that differ only in their line terminators
128        compare equal. This works on Linux.
129    
130    17. Under certain error circumstances pcregrep might try to free random memory
131        as it exited. This is now fixed, thanks to valgrind.
132    
133    19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
134        "abc\r\n\r\n", it found an unwanted second match after the second \r. This
135        was because its rules for how to advance for /g after matching an empty
136        string did not allow for this case. They now check for it specially.
137    
138    
139    Version 7.0 19-Dec-06
140    ---------------------
141    
142     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
143        moving to gcc 4.1.1.
144    
145     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
146        sys/time.h, which is documented as needed for this function. It doesn't
147        seem to matter on Linux, but it showed up on some releases of OS X.
148    
149     3. It seems that there are systems where bytes whose values are greater than
150        127 match isprint() in the "C" locale. The "C" locale should be the
151        default when a C program starts up. In most systems, only ASCII printing
152        characters match isprint(). This difference caused the output from pcretest
153        to vary, making some of the tests fail. I have changed pcretest so that:
154    
155        (a) When it is outputting text in the compiled version of a pattern, bytes
156            other than 32-126 are always shown as hex escapes.
157    
158        (b) When it is outputting text that is a matched part of a subject string,
159            it does the same, unless a different locale has been set for the match
160            (using the /L modifier). In this case, it uses isprint() to decide.
161    
162     4. Fixed a major bug that caused incorrect computation of the amount of memory
163        required for a compiled pattern when options that changed within the
164        pattern affected the logic of the preliminary scan that determines the
165        length. The relevant options are -x, and -i in UTF-8 mode. The result was
166        that the computed length was too small. The symptoms of this bug were
167        either the PCRE error "internal error: code overflow" from pcre_compile(),
168        or a glibc crash with a message such as "pcretest: free(): invalid next
169        size (fast)". Examples of patterns that provoked this bug (shown in
170        pcretest format) are:
171    
172          /(?-x: )/x
173          /(?x)(?-x: \s*#\s*)/
174          /((?i)[\x{c0}])/8
175          /(?i:[\x{c0}])/8
176    
177        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
178        is now done differently.
179    
180     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
181        wrapper classes; (b) implement a new function in the C++ scanner that is
182        more efficient than the old way of doing things because it avoids levels of
183        recursion in the regex matching; (c) add a paragraph to the documentation
184        for the FullMatch() function.
185    
186     6. The escape sequence \n was being treated as whatever was defined as
187        "newline". Not only was this contrary to the documentation, which states
188        that \n is character 10 (hex 0A), but it also went horribly wrong when
189        "newline" was defined as CRLF. This has been fixed.
190    
191     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
192        was being set to -1 for the "end of line" case (supposedly a value that no
193        character can have). Though this value is never used (the check for end of
194        line is "zero bytes in current character"), it caused compiler complaints.
195        I've changed it to 0xffffffff.
196    
197     8. In pcre_version.c, the version string was being built by a sequence of
198        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
199        string (as it is for production releases) called a macro with an empty
200        argument. The C standard says the result of this is undefined. The gcc
201        compiler treats it as an empty string (which was what was wanted) but it is
202        reported that Visual C gives an error. The source has been hacked around to
203        avoid this problem.
204    
205     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
206        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
207        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
208        of them did).
209    
210    10. Originally, pcretest opened its input and output without "b"; then I was
211        told that "b" was needed in some environments, so it was added for release
212        5.0 to both the input and output. (It makes no difference on Unix-like
213        systems.) Later I was told that it is wrong for the input on Windows. I've
214        now abstracted the modes into two macros, to make it easier to fiddle with
215        them, and removed "b" from the input mode under Windows.
216    
217    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
218    
219    12. Added -help and --help to pcretest as an official way of being reminded
220        of the options.
221    
222    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
223        and pcrecpp.cc because they annoy compilers at high warning levels.
224    
225    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
226    
227    15. Fixed an occurrence of == in configure.ac that should have been = (shell
228        scripts are not C programs :-) and which was not noticed because it works
229        on Linux.
230    
231    16. pcretest is supposed to handle any length of pattern and data line (as one
232        line or as a continued sequence of lines) by extending its input buffer if
233        necessary. This feature was broken for very long pattern lines, leading to
234        a string of junk being passed to pcre_compile() if the pattern was longer
235        than about 50K.
236    
237    17. I have done a major re-factoring of the way pcre_compile() computes the
238        amount of memory needed for a compiled pattern. Previously, there was code
239        that made a preliminary scan of the pattern in order to do this. That was
240        OK when PCRE was new, but as the facilities have expanded, it has become
241        harder and harder to keep it in step with the real compile phase, and there
242        have been a number of bugs (see for example, 4 above). I have now found a
243        cunning way of running the real compile function in a "fake" mode that
244        enables it to compute how much memory it would need, while actually only
245        ever using a few hundred bytes of working memory and without too many
246        tests of the mode. This should make future maintenance and development
247        easier. A side effect of this work is that the limit of 200 on the nesting
248        depth of parentheses has been removed (though this was never a serious
249        limitation, I suspect). However, there is a downside: pcre_compile() now
250        runs more slowly than before (30% or more, depending on the pattern). I
251        hope this isn't a big issue. There is no effect on runtime performance.
252    
253    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
254        newline (only possible for the last line of a file) and it was a
255        pattern that set a locale (followed by /Lsomething), pcretest crashed.
256    
257    19. Added additional timing features to pcretest. (1) The -tm option now times
258        matching only, not compiling. (2) Both -t and -tm can be followed, as a
259        separate command line item, by a number that specifies the number of
260        repeats to use when timing. The default is 50000; this gives better
261        precision, but takes uncomfortably long for very large patterns.
262    
263    20. Extended pcre_study() to be more clever in cases where a branch of a
264        subpattern has no definite first character. For example, (a*|b*)[cd] would
265        previously give no result from pcre_study(). Now it recognizes that the
266        first character must be a, b, c, or d.
267    
268    21. There was an incorrect error "recursive call could loop indefinitely" if
269        a subpattern (or the entire pattern) that was being tested for matching an
270        empty string contained only one non-empty item after a nested subpattern.
271        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
272        incorrectly, because the \d was being skipped in the check.
273    
274    22. The pcretest program now has a new pattern option /B and a command line
275        option -b, which is equivalent to adding /B to every pattern. This causes
276        it to show the compiled bytecode, without the additional information that
277        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
278        is the same as /B/I).
279    
280    23. A new optimization is now able automatically to treat some sequences such
281        as a*b as a*+b. More specifically, if something simple (such as a character
282        or a simple class like \d) has an unlimited quantifier, and is followed by
283        something that cannot possibly match the quantified thing, the quantifier
284        is automatically "possessified".
285    
286    24. A recursive reference to a subpattern whose number was greater than 39
287        went wrong under certain circumstances in UTF-8 mode. This bug could also
288        have affected the operation of pcre_study().
289    
290    25. Realized that a little bit of performance could be had by replacing
291        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
292    
293    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
294    
295    27. Possessive quantifiers such as a++ were previously implemented by turning
296        them into atomic groups such as ($>a+). Now they have their own opcodes,
297        which improves performance. This includes the automatically created ones
298        from 23 above.
299    
300    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
301        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
302        the first matched character to be a colon. This applied both to named and
303        numbered groups.
304    
305    29. The ucpinternal.h header file was missing its idempotency #ifdef.
306    
307    30. I was sent a "project" file called libpcre.a.dev which I understand makes
308        building PCRE on Windows easier, so I have included it in the distribution.
309    
310    31. There is now a check in pcretest against a ridiculously large number being
311        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
312        loop, the loop is abandoned.
313    
314    32. Forward references to subpatterns in conditions such as (?(2)...) where
315        subpattern 2 is defined later cause pcre_compile() to search forwards in
316        the pattern for the relevant set of parentheses. This search went wrong
317        when there were unescaped parentheses in a character class, parentheses
318        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
319    
320    33. "Subroutine" calls and backreferences were previously restricted to
321        referencing subpatterns earlier in the regex. This restriction has now
322        been removed.
323    
324    34. Added a number of extra features that are going to be in Perl 5.10. On the
325        whole, these are just syntactic alternatives for features that PCRE had
326        previously implemented using the Python syntax or my own invention. The
327        other formats are all retained for compatibility.
328    
329        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
330            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
331            also .NET compatible.
332    
333        (b) A recursion or subroutine call to a named group can now be defined as
334            (?&name) as well as (?P>name).
335    
336        (c) A backreference to a named group can now be defined as \k<name> or
337            \k'name' as well as (?P=name). The new forms, as well as being in Perl
338            5.10, are also .NET compatible.
339    
340        (d) A conditional reference to a named group can now use the syntax
341            (?(<name>) or (?('name') as well as (?(name).
342    
343        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
344            groups (named and numbered) that are never evaluated inline, but can be
345            called as "subroutines" from elsewhere. In effect, the DEFINE condition
346            is always false. There may be only one alternative in such a group.
347    
348        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
349            as the simple (?(R). The condition is true only if the most recent
350            recursion is that of the given number or name. It does not search out
351            through the entire recursion stack.
352    
353        (g) The escape \gN or \g{N} has been added, where N is a positive or
354            negative number, specifying an absolute or relative reference.
355    
356    35. Tidied to get rid of some further signed/unsigned compiler warnings and
357        some "unreachable code" warnings.
358    
359    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
360        things, this adds five new scripts.
361    
362    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
363        There were also incompatibilities regarding the handling of \Q..\E inside
364        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
365        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
366    
367    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
368        matches an empty string, and forcibly breaks the loop. There were bugs in
369        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
370        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
371        separate and independent bugs (that affected different cases) have been
372        fixed.
373    
374    39. Refactored the code to abolish the use of different opcodes for small
375        capturing bracket numbers. This is a tidy that I avoided doing when I
376        removed the limit on the number of capturing brackets for 3.5 back in 2001.
377        The new approach is not only tidier, it makes it possible to reduce the
378        memory needed to fix the previous bug (38).
379    
380    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
381        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
382        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
383        mode.
384    
385    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
386        report.
387    
388    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
389        copy construction and assignment in the C++ wrapper.
390    
391    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
392        couple of bugs that could have given wrong results in the "--newline=crlf"
393        case.
394    
395    44. Added a number of casts and did some reorganization of signed/unsigned int
396        variables following suggestions from Dair Grant. Also renamed the variable
397        "this" as "item" because it is a C++ keyword.
398    
399    45. Arranged for dftables to add
400    
401          #include "pcre_internal.h"
402    
403        to pcre_chartables.c because without it, gcc 4.x may remove the array
404        definition from the final binary if PCRE is built into a static library and
405        dead code stripping is activated.
406    
407    46. For an unanchored pattern, if a match attempt fails at the start of a
408        newline sequence, and the newline setting is CRLF or ANY, and the next two
409        characters are CRLF, advance by two characters instead of one.
410    
411    
412  Version 6.7 04-Jul-06  Version 6.7 04-Jul-06
413  ---------------------  ---------------------
414    

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