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revision 91 by nigel, Sat Feb 24 21:41:34 2007 UTC revision 111 by ph10, Thu Mar 8 16:53:09 2007 UTC
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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
3    
4    Version 7.1 05-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 maintain/132html script that I use to
25        generate HTML has been updated to handle .nf/.fi and to complain if it
26        encounters .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. The emulated memmove() function in pcre_internal.h (provided for those
64        environments that have neither memmove() nor bcopy()) was defining its
65        arguments as char * instead of void *.
66    
67    11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
68        and Detrail to create the HTML documentation, the .txt form of the man
69        pages, and it removes trailing spaces from listed files. It also creates
70        pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
71        case, it wraps all the #defines with #ifndefs. This script should be run
72        before "make dist".
73    
74    
75    Version 7.0 19-Dec-06
76    ---------------------
77    
78     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
79        moving to gcc 4.1.1.
80    
81     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
82        sys/time.h, which is documented as needed for this function. It doesn't
83        seem to matter on Linux, but it showed up on some releases of OS X.
84    
85     3. It seems that there are systems where bytes whose values are greater than
86        127 match isprint() in the "C" locale. The "C" locale should be the
87        default when a C program starts up. In most systems, only ASCII printing
88        characters match isprint(). This difference caused the output from pcretest
89        to vary, making some of the tests fail. I have changed pcretest so that:
90    
91        (a) When it is outputting text in the compiled version of a pattern, bytes
92            other than 32-126 are always shown as hex escapes.
93    
94        (b) When it is outputting text that is a matched part of a subject string,
95            it does the same, unless a different locale has been set for the match
96            (using the /L modifier). In this case, it uses isprint() to decide.
97    
98     4. Fixed a major bug that caused incorrect computation of the amount of memory
99        required for a compiled pattern when options that changed within the
100        pattern affected the logic of the preliminary scan that determines the
101        length. The relevant options are -x, and -i in UTF-8 mode. The result was
102        that the computed length was too small. The symptoms of this bug were
103        either the PCRE error "internal error: code overflow" from pcre_compile(),
104        or a glibc crash with a message such as "pcretest: free(): invalid next
105        size (fast)". Examples of patterns that provoked this bug (shown in
106        pcretest format) are:
107    
108          /(?-x: )/x
109          /(?x)(?-x: \s*#\s*)/
110          /((?i)[\x{c0}])/8
111          /(?i:[\x{c0}])/8
112    
113        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
114        is now done differently.
115    
116     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
117        wrapper classes; (b) implement a new function in the C++ scanner that is
118        more efficient than the old way of doing things because it avoids levels of
119        recursion in the regex matching; (c) add a paragraph to the documentation
120        for the FullMatch() function.
121    
122     6. The escape sequence \n was being treated as whatever was defined as
123        "newline". Not only was this contrary to the documentation, which states
124        that \n is character 10 (hex 0A), but it also went horribly wrong when
125        "newline" was defined as CRLF. This has been fixed.
126    
127     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
128        was being set to -1 for the "end of line" case (supposedly a value that no
129        character can have). Though this value is never used (the check for end of
130        line is "zero bytes in current character"), it caused compiler complaints.
131        I've changed it to 0xffffffff.
132    
133     8. In pcre_version.c, the version string was being built by a sequence of
134        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
135        string (as it is for production releases) called a macro with an empty
136        argument. The C standard says the result of this is undefined. The gcc
137        compiler treats it as an empty string (which was what was wanted) but it is
138        reported that Visual C gives an error. The source has been hacked around to
139        avoid this problem.
140    
141     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
142        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
143        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
144        of them did).
145    
146    10. Originally, pcretest opened its input and output without "b"; then I was
147        told that "b" was needed in some environments, so it was added for release
148        5.0 to both the input and output. (It makes no difference on Unix-like
149        systems.) Later I was told that it is wrong for the input on Windows. I've
150        now abstracted the modes into two macros, to make it easier to fiddle with
151        them, and removed "b" from the input mode under Windows.
152    
153    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
154    
155    12. Added -help and --help to pcretest as an official way of being reminded
156        of the options.
157    
158    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
159        and pcrecpp.cc because they annoy compilers at high warning levels.
160    
161    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
162    
163    15. Fixed an occurrence of == in configure.ac that should have been = (shell
164        scripts are not C programs :-) and which was not noticed because it works
165        on Linux.
166    
167    16. pcretest is supposed to handle any length of pattern and data line (as one
168        line or as a continued sequence of lines) by extending its input buffer if
169        necessary. This feature was broken for very long pattern lines, leading to
170        a string of junk being passed to pcre_compile() if the pattern was longer
171        than about 50K.
172    
173    17. I have done a major re-factoring of the way pcre_compile() computes the
174        amount of memory needed for a compiled pattern. Previously, there was code
175        that made a preliminary scan of the pattern in order to do this. That was
176        OK when PCRE was new, but as the facilities have expanded, it has become
177        harder and harder to keep it in step with the real compile phase, and there
178        have been a number of bugs (see for example, 4 above). I have now found a
179        cunning way of running the real compile function in a "fake" mode that
180        enables it to compute how much memory it would need, while actually only
181        ever using a few hundred bytes of working memory and without too many
182        tests of the mode. This should make future maintenance and development
183        easier. A side effect of this work is that the limit of 200 on the nesting
184        depth of parentheses has been removed (though this was never a serious
185        limitation, I suspect). However, there is a downside: pcre_compile() now
186        runs more slowly than before (30% or more, depending on the pattern). I
187        hope this isn't a big issue. There is no effect on runtime performance.
188    
189    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
190        newline (only possible for the last line of a file) and it was a
191        pattern that set a locale (followed by /Lsomething), pcretest crashed.
192    
193    19. Added additional timing features to pcretest. (1) The -tm option now times
194        matching only, not compiling. (2) Both -t and -tm can be followed, as a
195        separate command line item, by a number that specifies the number of
196        repeats to use when timing. The default is 50000; this gives better
197        precision, but takes uncomfortably long for very large patterns.
198    
199    20. Extended pcre_study() to be more clever in cases where a branch of a
200        subpattern has no definite first character. For example, (a*|b*)[cd] would
201        previously give no result from pcre_study(). Now it recognizes that the
202        first character must be a, b, c, or d.
203    
204    21. There was an incorrect error "recursive call could loop indefinitely" if
205        a subpattern (or the entire pattern) that was being tested for matching an
206        empty string contained only one non-empty item after a nested subpattern.
207        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
208        incorrectly, because the \d was being skipped in the check.
209    
210    22. The pcretest program now has a new pattern option /B and a command line
211        option -b, which is equivalent to adding /B to every pattern. This causes
212        it to show the compiled bytecode, without the additional information that
213        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
214        is the same as /B/I).
215    
216    23. A new optimization is now able automatically to treat some sequences such
217        as a*b as a*+b. More specifically, if something simple (such as a character
218        or a simple class like \d) has an unlimited quantifier, and is followed by
219        something that cannot possibly match the quantified thing, the quantifier
220        is automatically "possessified".
221    
222    24. A recursive reference to a subpattern whose number was greater than 39
223        went wrong under certain circumstances in UTF-8 mode. This bug could also
224        have affected the operation of pcre_study().
225    
226    25. Realized that a little bit of performance could be had by replacing
227        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
228    
229    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
230    
231    27. Possessive quantifiers such as a++ were previously implemented by turning
232        them into atomic groups such as ($>a+). Now they have their own opcodes,
233        which improves performance. This includes the automatically created ones
234        from 23 above.
235    
236    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
237        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
238        the first matched character to be a colon. This applied both to named and
239        numbered groups.
240    
241    29. The ucpinternal.h header file was missing its idempotency #ifdef.
242    
243    30. I was sent a "project" file called libpcre.a.dev which I understand makes
244        building PCRE on Windows easier, so I have included it in the distribution.
245    
246    31. There is now a check in pcretest against a ridiculously large number being
247        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
248        loop, the loop is abandoned.
249    
250    32. Forward references to subpatterns in conditions such as (?(2)...) where
251        subpattern 2 is defined later cause pcre_compile() to search forwards in
252        the pattern for the relevant set of parentheses. This search went wrong
253        when there were unescaped parentheses in a character class, parentheses
254        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
255    
256    33. "Subroutine" calls and backreferences were previously restricted to
257        referencing subpatterns earlier in the regex. This restriction has now
258        been removed.
259    
260    34. Added a number of extra features that are going to be in Perl 5.10. On the
261        whole, these are just syntactic alternatives for features that PCRE had
262        previously implemented using the Python syntax or my own invention. The
263        other formats are all retained for compatibility.
264    
265        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
266            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
267            also .NET compatible.
268    
269        (b) A recursion or subroutine call to a named group can now be defined as
270            (?&name) as well as (?P>name).
271    
272        (c) A backreference to a named group can now be defined as \k<name> or
273            \k'name' as well as (?P=name). The new forms, as well as being in Perl
274            5.10, are also .NET compatible.
275    
276        (d) A conditional reference to a named group can now use the syntax
277            (?(<name>) or (?('name') as well as (?(name).
278    
279        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
280            groups (named and numbered) that are never evaluated inline, but can be
281            called as "subroutines" from elsewhere. In effect, the DEFINE condition
282            is always false. There may be only one alternative in such a group.
283    
284        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
285            as the simple (?(R). The condition is true only if the most recent
286            recursion is that of the given number or name. It does not search out
287            through the entire recursion stack.
288    
289        (g) The escape \gN or \g{N} has been added, where N is a positive or
290            negative number, specifying an absolute or relative reference.
291    
292    35. Tidied to get rid of some further signed/unsigned compiler warnings and
293        some "unreachable code" warnings.
294    
295    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
296        things, this adds five new scripts.
297    
298    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
299        There were also incompatibilities regarding the handling of \Q..\E inside
300        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
301        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
302    
303    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
304        matches an empty string, and forcibly breaks the loop. There were bugs in
305        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
306        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
307        separate and independent bugs (that affected different cases) have been
308        fixed.
309    
310    39. Refactored the code to abolish the use of different opcodes for small
311        capturing bracket numbers. This is a tidy that I avoided doing when I
312        removed the limit on the number of capturing brackets for 3.5 back in 2001.
313        The new approach is not only tidier, it makes it possible to reduce the
314        memory needed to fix the previous bug (38).
315    
316    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
317        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
318        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
319        mode.
320    
321    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
322        report.
323    
324    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
325        copy construction and assignment in the C++ wrapper.
326    
327    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
328        couple of bugs that could have given wrong results in the "--newline=crlf"
329        case.
330    
331    44. Added a number of casts and did some reorganization of signed/unsigned int
332        variables following suggestions from Dair Grant. Also renamed the variable
333        "this" as "item" because it is a C++ keyword.
334    
335    45. Arranged for dftables to add
336    
337          #include "pcre_internal.h"
338    
339        to pcre_chartables.c because without it, gcc 4.x may remove the array
340        definition from the final binary if PCRE is built into a static library and
341        dead code stripping is activated.
342    
343    46. For an unanchored pattern, if a match attempt fails at the start of a
344        newline sequence, and the newline setting is CRLF or ANY, and the next two
345        characters are CRLF, advance by two characters instead of one.
346    
347    
348  Version 6.7 04-Jul-06  Version 6.7 04-Jul-06
349  ---------------------  ---------------------
350    

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