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1  ChangeLog for PCRE  ChangeLog for PCRE
2  ------------------  ------------------
4    Version 7.1 05-Mar-07
5    ---------------------
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.
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.
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.
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, for the benefit
30        of those who have to compile without Autotools (compare pcre.h).
32     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
33        Weber: (1) pcre_internal.h was missing some function renames; (2) updated
34        makevp.bat for the current PCRE, using the additional files !compile.txt,
35        !linklib.txt, and pcregexp.pas.
37     6. A Windows user reported a minor discrepancy with test 2, which turned out
38        to be caused by a trailing space on an input line that had got lost in his
39        copy. The trailing space was an accident, so I've just removed it.
41     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
42        that is needed.
44     8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
45        as "const" (a) because they are and (b) because it helps the PHP
46        maintainers who have recently made a script to detect big data structures
47        in the php code that should be moved to the .rodata section. I remembered
48        to update Builducptable as well, so it won't revert if ucptable.h is ever
49        re-created.
51     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
52        pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
53        order to be able to cut out the UTF-8 tables in the latter when UTF-8
54        support is not required. This saves 1.5-2K of code, which is important in
55        some applications.
57        Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
58        so as not to refer to the tables, even though these functions will never be
59        called when UTF-8 support is disabled. Otherwise there are problems with a
60        shared library.
62    10. The emulated memmove() function in pcre_internal.h (provided for those
63        environments that have neither memmove() nor bcopy()) was defining its
64        arguments as char * instead of void *.
67    Version 7.0 19-Dec-06
68    ---------------------
70     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
71        moving to gcc 4.1.1.
73     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
74        sys/time.h, which is documented as needed for this function. It doesn't
75        seem to matter on Linux, but it showed up on some releases of OS X.
77     3. It seems that there are systems where bytes whose values are greater than
78        127 match isprint() in the "C" locale. The "C" locale should be the
79        default when a C program starts up. In most systems, only ASCII printing
80        characters match isprint(). This difference caused the output from pcretest
81        to vary, making some of the tests fail. I have changed pcretest so that:
83        (a) When it is outputting text in the compiled version of a pattern, bytes
84            other than 32-126 are always shown as hex escapes.
86        (b) When it is outputting text that is a matched part of a subject string,
87            it does the same, unless a different locale has been set for the match
88            (using the /L modifier). In this case, it uses isprint() to decide.
90     4. Fixed a major bug that caused incorrect computation of the amount of memory
91        required for a compiled pattern when options that changed within the
92        pattern affected the logic of the preliminary scan that determines the
93        length. The relevant options are -x, and -i in UTF-8 mode. The result was
94        that the computed length was too small. The symptoms of this bug were
95        either the PCRE error "internal error: code overflow" from pcre_compile(),
96        or a glibc crash with a message such as "pcretest: free(): invalid next
97        size (fast)". Examples of patterns that provoked this bug (shown in
98        pcretest format) are:
100          /(?-x: )/x
101          /(?x)(?-x: \s*#\s*)/
102          /((?i)[\x{c0}])/8
103          /(?i:[\x{c0}])/8
105        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
106        is now done differently.
108     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
109        wrapper classes; (b) implement a new function in the C++ scanner that is
110        more efficient than the old way of doing things because it avoids levels of
111        recursion in the regex matching; (c) add a paragraph to the documentation
112        for the FullMatch() function.
114     6. The escape sequence \n was being treated as whatever was defined as
115        "newline". Not only was this contrary to the documentation, which states
116        that \n is character 10 (hex 0A), but it also went horribly wrong when
117        "newline" was defined as CRLF. This has been fixed.
119     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
120        was being set to -1 for the "end of line" case (supposedly a value that no
121        character can have). Though this value is never used (the check for end of
122        line is "zero bytes in current character"), it caused compiler complaints.
123        I've changed it to 0xffffffff.
125     8. In pcre_version.c, the version string was being built by a sequence of
126        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
127        string (as it is for production releases) called a macro with an empty
128        argument. The C standard says the result of this is undefined. The gcc
129        compiler treats it as an empty string (which was what was wanted) but it is
130        reported that Visual C gives an error. The source has been hacked around to
131        avoid this problem.
133     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
134        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
135        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
136        of them did).
138    10. Originally, pcretest opened its input and output without "b"; then I was
139        told that "b" was needed in some environments, so it was added for release
140        5.0 to both the input and output. (It makes no difference on Unix-like
141        systems.) Later I was told that it is wrong for the input on Windows. I've
142        now abstracted the modes into two macros, to make it easier to fiddle with
143        them, and removed "b" from the input mode under Windows.
145    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
147    12. Added -help and --help to pcretest as an official way of being reminded
148        of the options.
150    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
151        and pcrecpp.cc because they annoy compilers at high warning levels.
153    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
155    15. Fixed an occurrence of == in configure.ac that should have been = (shell
156        scripts are not C programs :-) and which was not noticed because it works
157        on Linux.
159    16. pcretest is supposed to handle any length of pattern and data line (as one
160        line or as a continued sequence of lines) by extending its input buffer if
161        necessary. This feature was broken for very long pattern lines, leading to
162        a string of junk being passed to pcre_compile() if the pattern was longer
163        than about 50K.
165    17. I have done a major re-factoring of the way pcre_compile() computes the
166        amount of memory needed for a compiled pattern. Previously, there was code
167        that made a preliminary scan of the pattern in order to do this. That was
168        OK when PCRE was new, but as the facilities have expanded, it has become
169        harder and harder to keep it in step with the real compile phase, and there
170        have been a number of bugs (see for example, 4 above). I have now found a
171        cunning way of running the real compile function in a "fake" mode that
172        enables it to compute how much memory it would need, while actually only
173        ever using a few hundred bytes of working memory and without too many
174        tests of the mode. This should make future maintenance and development
175        easier. A side effect of this work is that the limit of 200 on the nesting
176        depth of parentheses has been removed (though this was never a serious
177        limitation, I suspect). However, there is a downside: pcre_compile() now
178        runs more slowly than before (30% or more, depending on the pattern). I
179        hope this isn't a big issue. There is no effect on runtime performance.
181    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
182        newline (only possible for the last line of a file) and it was a
183        pattern that set a locale (followed by /Lsomething), pcretest crashed.
185    19. Added additional timing features to pcretest. (1) The -tm option now times
186        matching only, not compiling. (2) Both -t and -tm can be followed, as a
187        separate command line item, by a number that specifies the number of
188        repeats to use when timing. The default is 50000; this gives better
189        precision, but takes uncomfortably long for very large patterns.
191    20. Extended pcre_study() to be more clever in cases where a branch of a
192        subpattern has no definite first character. For example, (a*|b*)[cd] would
193        previously give no result from pcre_study(). Now it recognizes that the
194        first character must be a, b, c, or d.
196    21. There was an incorrect error "recursive call could loop indefinitely" if
197        a subpattern (or the entire pattern) that was being tested for matching an
198        empty string contained only one non-empty item after a nested subpattern.
199        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
200        incorrectly, because the \d was being skipped in the check.
202    22. The pcretest program now has a new pattern option /B and a command line
203        option -b, which is equivalent to adding /B to every pattern. This causes
204        it to show the compiled bytecode, without the additional information that
205        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
206        is the same as /B/I).
208    23. A new optimization is now able automatically to treat some sequences such
209        as a*b as a*+b. More specifically, if something simple (such as a character
210        or a simple class like \d) has an unlimited quantifier, and is followed by
211        something that cannot possibly match the quantified thing, the quantifier
212        is automatically "possessified".
214    24. A recursive reference to a subpattern whose number was greater than 39
215        went wrong under certain circumstances in UTF-8 mode. This bug could also
216        have affected the operation of pcre_study().
218    25. Realized that a little bit of performance could be had by replacing
219        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
221    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
223    27. Possessive quantifiers such as a++ were previously implemented by turning
224        them into atomic groups such as ($>a+). Now they have their own opcodes,
225        which improves performance. This includes the automatically created ones
226        from 23 above.
228    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
229        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
230        the first matched character to be a colon. This applied both to named and
231        numbered groups.
233    29. The ucpinternal.h header file was missing its idempotency #ifdef.
235    30. I was sent a "project" file called libpcre.a.dev which I understand makes
236        building PCRE on Windows easier, so I have included it in the distribution.
238    31. There is now a check in pcretest against a ridiculously large number being
239        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
240        loop, the loop is abandoned.
242    32. Forward references to subpatterns in conditions such as (?(2)...) where
243        subpattern 2 is defined later cause pcre_compile() to search forwards in
244        the pattern for the relevant set of parentheses. This search went wrong
245        when there were unescaped parentheses in a character class, parentheses
246        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
248    33. "Subroutine" calls and backreferences were previously restricted to
249        referencing subpatterns earlier in the regex. This restriction has now
250        been removed.
252    34. Added a number of extra features that are going to be in Perl 5.10. On the
253        whole, these are just syntactic alternatives for features that PCRE had
254        previously implemented using the Python syntax or my own invention. The
255        other formats are all retained for compatibility.
257        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
258            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
259            also .NET compatible.
261        (b) A recursion or subroutine call to a named group can now be defined as
262            (?&name) as well as (?P>name).
264        (c) A backreference to a named group can now be defined as \k<name> or
265            \k'name' as well as (?P=name). The new forms, as well as being in Perl
266            5.10, are also .NET compatible.
268        (d) A conditional reference to a named group can now use the syntax
269            (?(<name>) or (?('name') as well as (?(name).
271        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
272            groups (named and numbered) that are never evaluated inline, but can be
273            called as "subroutines" from elsewhere. In effect, the DEFINE condition
274            is always false. There may be only one alternative in such a group.
276        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
277            as the simple (?(R). The condition is true only if the most recent
278            recursion is that of the given number or name. It does not search out
279            through the entire recursion stack.
281        (g) The escape \gN or \g{N} has been added, where N is a positive or
282            negative number, specifying an absolute or relative reference.
284    35. Tidied to get rid of some further signed/unsigned compiler warnings and
285        some "unreachable code" warnings.
287    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
288        things, this adds five new scripts.
290    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
291        There were also incompatibilities regarding the handling of \Q..\E inside
292        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
293        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
295    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
296        matches an empty string, and forcibly breaks the loop. There were bugs in
297        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
298        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
299        separate and independent bugs (that affected different cases) have been
300        fixed.
302    39. Refactored the code to abolish the use of different opcodes for small
303        capturing bracket numbers. This is a tidy that I avoided doing when I
304        removed the limit on the number of capturing brackets for 3.5 back in 2001.
305        The new approach is not only tidier, it makes it possible to reduce the
306        memory needed to fix the previous bug (38).
308    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
309        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
310        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
311        mode.
313    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
314        report.
316    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
317        copy construction and assignment in the C++ wrapper.
319    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
320        couple of bugs that could have given wrong results in the "--newline=crlf"
321        case.
323    44. Added a number of casts and did some reorganization of signed/unsigned int
324        variables following suggestions from Dair Grant. Also renamed the variable
325        "this" as "item" because it is a C++ keyword.
327    45. Arranged for dftables to add
329          #include "pcre_internal.h"
331        to pcre_chartables.c because without it, gcc 4.x may remove the array
332        definition from the final binary if PCRE is built into a static library and
333        dead code stripping is activated.
335    46. For an unanchored pattern, if a match attempt fails at the start of a
336        newline sequence, and the newline setting is CRLF or ANY, and the next two
337        characters are CRLF, advance by two characters instead of one.
340    Version 6.7 04-Jul-06
341    ---------------------
343     1. In order to handle tests when input lines are enormously long, pcretest has
344        been re-factored so that it automatically extends its buffers when
345        necessary. The code is crude, but this _is_ just a test program. The
346        default size has been increased from 32K to 50K.
348     2. The code in pcre_study() was using the value of the re argument before
349        testing it for NULL. (Of course, in any sensible call of the function, it
350        won't be NULL.)
352     3. The memmove() emulation function in pcre_internal.h, which is used on
353        systems that lack both memmove() and bcopy() - that is, hardly ever -
354        was missing a "static" storage class specifier.
356     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
357        containing an extended class (one that cannot be represented by a bitmap
358        because it contains high-valued characters or Unicode property items, e.g.
359        [\pZ]). Almost always one would set UTF-8 mode when processing such a
360        pattern, but PCRE should not loop if you do not (it no longer does).
361        [Detail: two cases were found: (a) a repeated subpattern containing an
362        extended class; (b) a recursive reference to a subpattern that followed a
363        previous extended class. It wasn't skipping over the extended class
364        correctly when UTF-8 mode was not set.]
366     5. A negated single-character class was not being recognized as fixed-length
367        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
368        compile error "lookbehind assertion is not fixed length".
370     6. The RunPerlTest auxiliary script was showing an unexpected difference
371        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
372        write a Perl script that can interpret lines of an input file either as
373        byte characters or as UTF-8, which is what "perltest" was being required to
374        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
375        can't do is switch easily at run time between having the "use utf8;" pragma
376        or not. In the end, I fudged it by using the RunPerlTest script to insert
377        "use utf8;" explicitly for the UTF-8 tests.
379     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
380        the end of the subject string, contrary to the documentation and to what
381        Perl does. This was true of both matching functions. Now it matches only at
382        the start of the subject and immediately after *internal* newlines.
384     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
385        a pointer to an int instead of a pointer to an unsigned long int. This
386        caused problems on 64-bit systems.
388     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
389        instance of the 'standard' template library not being so standard".
391    10. There was no check on the number of named subpatterns nor the maximum
392        length of a subpattern name. The product of these values is used to compute
393        the size of the memory block for a compiled pattern. By supplying a very
394        long subpattern name and a large number of named subpatterns, the size
395        computation could be caused to overflow. This is now prevented by limiting
396        the length of names to 32 characters, and the number of named subpatterns
397        to 10,000.
399    11. Subpatterns that are repeated with specific counts have to be replicated in
400        the compiled pattern. The size of memory for this was computed from the
401        length of the subpattern and the repeat count. The latter is limited to
402        65535, but there was no limit on the former, meaning that integer overflow
403        could in principle occur. The compiled length of a repeated subpattern is
404        now limited to 30,000 bytes in order to prevent this.
406    12. Added the optional facility to have named substrings with the same name.
408    13. Added the ability to use a named substring as a condition, using the
409        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
410        are numbers (not recommended). Forward references are permitted.
412    14. Added forward references in named backreferences (if you see what I mean).
414    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
415        pattern could run off the end of the subject. For example, the pattern
416        "(?s)(.{1,5})"8 did this with the subject "ab".
418    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
419        PCRE_CASELESS was set when matching characters that were quantified with ?
420        or *.
422    17. A character class other than a single negated character that had a minimum
423        but no maximum quantifier - for example [ab]{6,} - was not handled
424        correctly by pce_dfa_exec(). It would match only one character.
426    18. A valid (though odd) pattern that looked like a POSIX character
427        class but used an invalid character after [ (for example [[,abc,]]) caused
428        pcre_compile() to give the error "Failed: internal error: code overflow" or
429        in some cases to crash with a glibc free() error. This could even happen if
430        the pattern terminated after [[ but there just happened to be a sequence of
431        letters, a binary zero, and a closing ] in the memory that followed.
433    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
434        over the years. Originally (before any Unicode support), just the bottom 8
435        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
436        output from "man perlunicode" includes this:
438          The regular expression compiler produces polymorphic opcodes.  That
439          is, the pattern adapts to the data and automatically switches to
440          the Unicode character scheme when presented with Unicode data--or
441          instead uses a traditional byte scheme when presented with byte
442          data.
444        Sadly, a wide octal escape does not cause a switch, and in a string with
445        no other multibyte characters, these octal escapes are treated as before.
446        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
447        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
448        Unicode string.
450        I have not perpetrated such confusion in PCRE. Up till now, it took just
451        the bottom 8 bits, as in old Perl. I have now made octal escapes with
452        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
453        translate to the appropriate multibyte character.
455    29. Applied some refactoring to reduce the number of warnings from Microsoft
456        and Borland compilers. This has included removing the fudge introduced
457        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
458        a warning about an unused variable.
460    21. PCRE has not included VT (character 0x0b) in the set of whitespace
461        characters since release 4.0, because Perl (from release 5.004) does not.
462        [Or at least, is documented not to: some releases seem to be in conflict
463        with the documentation.] However, when a pattern was studied with
464        pcre_study() and all its branches started with \s, PCRE still included VT
465        as a possible starting character. Of course, this did no harm; it just
466        caused an unnecessary match attempt.
468    22. Removed a now-redundant internal flag bit that recorded the fact that case
469        dependency changed within the pattern. This was once needed for "required
470        byte" processing, but is no longer used. This recovers a now-scarce options
471        bit. Also moved the least significant internal flag bit to the most-
472        significant bit of the word, which was not previously used (hangover from
473        the days when it was an int rather than a uint) to free up another bit for
474        the future.
476    23. Added support for CRLF line endings as well as CR and LF. As well as the
477        default being selectable at build time, it can now be changed at runtime
478        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
479        specify that it is scanning data with non-default line endings.
481    24. Changed the definition of CXXLINK to make it agree with the definition of
482        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
484    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
485        recursions. This makes a big different to stack usage for some patterns.
487    26. If a subpattern containing a named recursion or subroutine reference such
488        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
489        the space required for the compiled pattern went wrong and gave too small a
490        value. Depending on the environment, this could lead to "Failed: internal
491        error: code overflow at offset 49" or "glibc detected double free or
492        corruption" errors.
494    27. Applied patches from Google (a) to support the new newline modes and (b) to
495        advance over multibyte UTF-8 characters in GlobalReplace.
497    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
498        difference for some implementation of PCRE in some Windows version.
500    29. Added some extra testing facilities to pcretest:
502        \q<number>   in a data line sets the "match limit" value
503        \Q<number>   in a data line sets the "match recursion limt" value
504        -S <number>  sets the stack size, where <number> is in megabytes
506        The -S option isn't available for Windows.
509    Version 6.6 06-Feb-06
510    ---------------------
512     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
513        in pcreposix.h. I have copied the definition from pcre.h.
515     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
516        because pcre.h is no longer a built file.
518     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
519        not normally included in the compiled code.
522  Version 6.5 01-Feb-06  Version 6.5 01-Feb-06
523  ---------------------  ---------------------

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