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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).
33    Version 7.0 19-Dec-06
34    ---------------------
36     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
37        moving to gcc 4.1.1.
39     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
40        sys/time.h, which is documented as needed for this function. It doesn't
41        seem to matter on Linux, but it showed up on some releases of OS X.
43     3. It seems that there are systems where bytes whose values are greater than
44        127 match isprint() in the "C" locale. The "C" locale should be the
45        default when a C program starts up. In most systems, only ASCII printing
46        characters match isprint(). This difference caused the output from pcretest
47        to vary, making some of the tests fail. I have changed pcretest so that:
49        (a) When it is outputting text in the compiled version of a pattern, bytes
50            other than 32-126 are always shown as hex escapes.
52        (b) When it is outputting text that is a matched part of a subject string,
53            it does the same, unless a different locale has been set for the match
54            (using the /L modifier). In this case, it uses isprint() to decide.
56     4. Fixed a major bug that caused incorrect computation of the amount of memory
57        required for a compiled pattern when options that changed within the
58        pattern affected the logic of the preliminary scan that determines the
59        length. The relevant options are -x, and -i in UTF-8 mode. The result was
60        that the computed length was too small. The symptoms of this bug were
61        either the PCRE error "internal error: code overflow" from pcre_compile(),
62        or a glibc crash with a message such as "pcretest: free(): invalid next
63        size (fast)". Examples of patterns that provoked this bug (shown in
64        pcretest format) are:
66          /(?-x: )/x
67          /(?x)(?-x: \s*#\s*)/
68          /((?i)[\x{c0}])/8
69          /(?i:[\x{c0}])/8
71        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
72        is now done differently.
74     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
75        wrapper classes; (b) implement a new function in the C++ scanner that is
76        more efficient than the old way of doing things because it avoids levels of
77        recursion in the regex matching; (c) add a paragraph to the documentation
78        for the FullMatch() function.
80     6. The escape sequence \n was being treated as whatever was defined as
81        "newline". Not only was this contrary to the documentation, which states
82        that \n is character 10 (hex 0A), but it also went horribly wrong when
83        "newline" was defined as CRLF. This has been fixed.
85     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
86        was being set to -1 for the "end of line" case (supposedly a value that no
87        character can have). Though this value is never used (the check for end of
88        line is "zero bytes in current character"), it caused compiler complaints.
89        I've changed it to 0xffffffff.
91     8. In pcre_version.c, the version string was being built by a sequence of
92        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
93        string (as it is for production releases) called a macro with an empty
94        argument. The C standard says the result of this is undefined. The gcc
95        compiler treats it as an empty string (which was what was wanted) but it is
96        reported that Visual C gives an error. The source has been hacked around to
97        avoid this problem.
99     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
100        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
101        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
102        of them did).
104    10. Originally, pcretest opened its input and output without "b"; then I was
105        told that "b" was needed in some environments, so it was added for release
106        5.0 to both the input and output. (It makes no difference on Unix-like
107        systems.) Later I was told that it is wrong for the input on Windows. I've
108        now abstracted the modes into two macros, to make it easier to fiddle with
109        them, and removed "b" from the input mode under Windows.
111    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
113    12. Added -help and --help to pcretest as an official way of being reminded
114        of the options.
116    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
117        and pcrecpp.cc because they annoy compilers at high warning levels.
119    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
121    15. Fixed an occurrence of == in configure.ac that should have been = (shell
122        scripts are not C programs :-) and which was not noticed because it works
123        on Linux.
125    16. pcretest is supposed to handle any length of pattern and data line (as one
126        line or as a continued sequence of lines) by extending its input buffer if
127        necessary. This feature was broken for very long pattern lines, leading to
128        a string of junk being passed to pcre_compile() if the pattern was longer
129        than about 50K.
131    17. I have done a major re-factoring of the way pcre_compile() computes the
132        amount of memory needed for a compiled pattern. Previously, there was code
133        that made a preliminary scan of the pattern in order to do this. That was
134        OK when PCRE was new, but as the facilities have expanded, it has become
135        harder and harder to keep it in step with the real compile phase, and there
136        have been a number of bugs (see for example, 4 above). I have now found a
137        cunning way of running the real compile function in a "fake" mode that
138        enables it to compute how much memory it would need, while actually only
139        ever using a few hundred bytes of working memory and without too many
140        tests of the mode. This should make future maintenance and development
141        easier. A side effect of this work is that the limit of 200 on the nesting
142        depth of parentheses has been removed (though this was never a serious
143        limitation, I suspect). However, there is a downside: pcre_compile() now
144        runs more slowly than before (30% or more, depending on the pattern). I
145        hope this isn't a big issue. There is no effect on runtime performance.
147    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
148        newline (only possible for the last line of a file) and it was a
149        pattern that set a locale (followed by /Lsomething), pcretest crashed.
151    19. Added additional timing features to pcretest. (1) The -tm option now times
152        matching only, not compiling. (2) Both -t and -tm can be followed, as a
153        separate command line item, by a number that specifies the number of
154        repeats to use when timing. The default is 50000; this gives better
155        precision, but takes uncomfortably long for very large patterns.
157    20. Extended pcre_study() to be more clever in cases where a branch of a
158        subpattern has no definite first character. For example, (a*|b*)[cd] would
159        previously give no result from pcre_study(). Now it recognizes that the
160        first character must be a, b, c, or d.
162    21. There was an incorrect error "recursive call could loop indefinitely" if
163        a subpattern (or the entire pattern) that was being tested for matching an
164        empty string contained only one non-empty item after a nested subpattern.
165        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
166        incorrectly, because the \d was being skipped in the check.
168    22. The pcretest program now has a new pattern option /B and a command line
169        option -b, which is equivalent to adding /B to every pattern. This causes
170        it to show the compiled bytecode, without the additional information that
171        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
172        is the same as /B/I).
174    23. A new optimization is now able automatically to treat some sequences such
175        as a*b as a*+b. More specifically, if something simple (such as a character
176        or a simple class like \d) has an unlimited quantifier, and is followed by
177        something that cannot possibly match the quantified thing, the quantifier
178        is automatically "possessified".
180    24. A recursive reference to a subpattern whose number was greater than 39
181        went wrong under certain circumstances in UTF-8 mode. This bug could also
182        have affected the operation of pcre_study().
184    25. Realized that a little bit of performance could be had by replacing
185        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
187    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
189    27. Possessive quantifiers such as a++ were previously implemented by turning
190        them into atomic groups such as ($>a+). Now they have their own opcodes,
191        which improves performance. This includes the automatically created ones
192        from 23 above.
194    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
195        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
196        the first matched character to be a colon. This applied both to named and
197        numbered groups.
199    29. The ucpinternal.h header file was missing its idempotency #ifdef.
201    30. I was sent a "project" file called libpcre.a.dev which I understand makes
202        building PCRE on Windows easier, so I have included it in the distribution.
204    31. There is now a check in pcretest against a ridiculously large number being
205        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
206        loop, the loop is abandoned.
208    32. Forward references to subpatterns in conditions such as (?(2)...) where
209        subpattern 2 is defined later cause pcre_compile() to search forwards in
210        the pattern for the relevant set of parentheses. This search went wrong
211        when there were unescaped parentheses in a character class, parentheses
212        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
214    33. "Subroutine" calls and backreferences were previously restricted to
215        referencing subpatterns earlier in the regex. This restriction has now
216        been removed.
218    34. Added a number of extra features that are going to be in Perl 5.10. On the
219        whole, these are just syntactic alternatives for features that PCRE had
220        previously implemented using the Python syntax or my own invention. The
221        other formats are all retained for compatibility.
223        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
224            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
225            also .NET compatible.
227        (b) A recursion or subroutine call to a named group can now be defined as
228            (?&name) as well as (?P>name).
230        (c) A backreference to a named group can now be defined as \k<name> or
231            \k'name' as well as (?P=name). The new forms, as well as being in Perl
232            5.10, are also .NET compatible.
234        (d) A conditional reference to a named group can now use the syntax
235            (?(<name>) or (?('name') as well as (?(name).
237        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
238            groups (named and numbered) that are never evaluated inline, but can be
239            called as "subroutines" from elsewhere. In effect, the DEFINE condition
240            is always false. There may be only one alternative in such a group.
242        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
243            as the simple (?(R). The condition is true only if the most recent
244            recursion is that of the given number or name. It does not search out
245            through the entire recursion stack.
247        (g) The escape \gN or \g{N} has been added, where N is a positive or
248            negative number, specifying an absolute or relative reference.
250    35. Tidied to get rid of some further signed/unsigned compiler warnings and
251        some "unreachable code" warnings.
253    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
254        things, this adds five new scripts.
256    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
257        There were also incompatibilities regarding the handling of \Q..\E inside
258        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
259        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
261    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
262        matches an empty string, and forcibly breaks the loop. There were bugs in
263        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
264        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
265        separate and independent bugs (that affected different cases) have been
266        fixed.
268    39. Refactored the code to abolish the use of different opcodes for small
269        capturing bracket numbers. This is a tidy that I avoided doing when I
270        removed the limit on the number of capturing brackets for 3.5 back in 2001.
271        The new approach is not only tidier, it makes it possible to reduce the
272        memory needed to fix the previous bug (38).
274    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
275        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
276        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
277        mode.
279    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
280        report.
282    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
283        copy construction and assignment in the C++ wrapper.
285    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
286        couple of bugs that could have given wrong results in the "--newline=crlf"
287        case.
289    44. Added a number of casts and did some reorganization of signed/unsigned int
290        variables following suggestions from Dair Grant. Also renamed the variable
291        "this" as "item" because it is a C++ keyword.
293    45. Arranged for dftables to add
295          #include "pcre_internal.h"
297        to pcre_chartables.c because without it, gcc 4.x may remove the array
298        definition from the final binary if PCRE is built into a static library and
299        dead code stripping is activated.
301    46. For an unanchored pattern, if a match attempt fails at the start of a
302        newline sequence, and the newline setting is CRLF or ANY, and the next two
303        characters are CRLF, advance by two characters instead of one.
306    Version 6.7 04-Jul-06
307    ---------------------
309     1. In order to handle tests when input lines are enormously long, pcretest has
310        been re-factored so that it automatically extends its buffers when
311        necessary. The code is crude, but this _is_ just a test program. The
312        default size has been increased from 32K to 50K.
314     2. The code in pcre_study() was using the value of the re argument before
315        testing it for NULL. (Of course, in any sensible call of the function, it
316        won't be NULL.)
318     3. The memmove() emulation function in pcre_internal.h, which is used on
319        systems that lack both memmove() and bcopy() - that is, hardly ever -
320        was missing a "static" storage class specifier.
322     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
323        containing an extended class (one that cannot be represented by a bitmap
324        because it contains high-valued characters or Unicode property items, e.g.
325        [\pZ]). Almost always one would set UTF-8 mode when processing such a
326        pattern, but PCRE should not loop if you do not (it no longer does).
327        [Detail: two cases were found: (a) a repeated subpattern containing an
328        extended class; (b) a recursive reference to a subpattern that followed a
329        previous extended class. It wasn't skipping over the extended class
330        correctly when UTF-8 mode was not set.]
332     5. A negated single-character class was not being recognized as fixed-length
333        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
334        compile error "lookbehind assertion is not fixed length".
336     6. The RunPerlTest auxiliary script was showing an unexpected difference
337        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
338        write a Perl script that can interpret lines of an input file either as
339        byte characters or as UTF-8, which is what "perltest" was being required to
340        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
341        can't do is switch easily at run time between having the "use utf8;" pragma
342        or not. In the end, I fudged it by using the RunPerlTest script to insert
343        "use utf8;" explicitly for the UTF-8 tests.
345     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
346        the end of the subject string, contrary to the documentation and to what
347        Perl does. This was true of both matching functions. Now it matches only at
348        the start of the subject and immediately after *internal* newlines.
350     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
351        a pointer to an int instead of a pointer to an unsigned long int. This
352        caused problems on 64-bit systems.
354     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
355        instance of the 'standard' template library not being so standard".
357    10. There was no check on the number of named subpatterns nor the maximum
358        length of a subpattern name. The product of these values is used to compute
359        the size of the memory block for a compiled pattern. By supplying a very
360        long subpattern name and a large number of named subpatterns, the size
361        computation could be caused to overflow. This is now prevented by limiting
362        the length of names to 32 characters, and the number of named subpatterns
363        to 10,000.
365    11. Subpatterns that are repeated with specific counts have to be replicated in
366        the compiled pattern. The size of memory for this was computed from the
367        length of the subpattern and the repeat count. The latter is limited to
368        65535, but there was no limit on the former, meaning that integer overflow
369        could in principle occur. The compiled length of a repeated subpattern is
370        now limited to 30,000 bytes in order to prevent this.
372    12. Added the optional facility to have named substrings with the same name.
374    13. Added the ability to use a named substring as a condition, using the
375        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
376        are numbers (not recommended). Forward references are permitted.
378    14. Added forward references in named backreferences (if you see what I mean).
380    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
381        pattern could run off the end of the subject. For example, the pattern
382        "(?s)(.{1,5})"8 did this with the subject "ab".
384    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
385        PCRE_CASELESS was set when matching characters that were quantified with ?
386        or *.
388    17. A character class other than a single negated character that had a minimum
389        but no maximum quantifier - for example [ab]{6,} - was not handled
390        correctly by pce_dfa_exec(). It would match only one character.
392    18. A valid (though odd) pattern that looked like a POSIX character
393        class but used an invalid character after [ (for example [[,abc,]]) caused
394        pcre_compile() to give the error "Failed: internal error: code overflow" or
395        in some cases to crash with a glibc free() error. This could even happen if
396        the pattern terminated after [[ but there just happened to be a sequence of
397        letters, a binary zero, and a closing ] in the memory that followed.
399    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
400        over the years. Originally (before any Unicode support), just the bottom 8
401        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
402        output from "man perlunicode" includes this:
404          The regular expression compiler produces polymorphic opcodes.  That
405          is, the pattern adapts to the data and automatically switches to
406          the Unicode character scheme when presented with Unicode data--or
407          instead uses a traditional byte scheme when presented with byte
408          data.
410        Sadly, a wide octal escape does not cause a switch, and in a string with
411        no other multibyte characters, these octal escapes are treated as before.
412        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
413        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
414        Unicode string.
416        I have not perpetrated such confusion in PCRE. Up till now, it took just
417        the bottom 8 bits, as in old Perl. I have now made octal escapes with
418        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
419        translate to the appropriate multibyte character.
421    29. Applied some refactoring to reduce the number of warnings from Microsoft
422        and Borland compilers. This has included removing the fudge introduced
423        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
424        a warning about an unused variable.
426    21. PCRE has not included VT (character 0x0b) in the set of whitespace
427        characters since release 4.0, because Perl (from release 5.004) does not.
428        [Or at least, is documented not to: some releases seem to be in conflict
429        with the documentation.] However, when a pattern was studied with
430        pcre_study() and all its branches started with \s, PCRE still included VT
431        as a possible starting character. Of course, this did no harm; it just
432        caused an unnecessary match attempt.
434    22. Removed a now-redundant internal flag bit that recorded the fact that case
435        dependency changed within the pattern. This was once needed for "required
436        byte" processing, but is no longer used. This recovers a now-scarce options
437        bit. Also moved the least significant internal flag bit to the most-
438        significant bit of the word, which was not previously used (hangover from
439        the days when it was an int rather than a uint) to free up another bit for
440        the future.
442    23. Added support for CRLF line endings as well as CR and LF. As well as the
443        default being selectable at build time, it can now be changed at runtime
444        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
445        specify that it is scanning data with non-default line endings.
447    24. Changed the definition of CXXLINK to make it agree with the definition of
448        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
450    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
451        recursions. This makes a big different to stack usage for some patterns.
453    26. If a subpattern containing a named recursion or subroutine reference such
454        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
455        the space required for the compiled pattern went wrong and gave too small a
456        value. Depending on the environment, this could lead to "Failed: internal
457        error: code overflow at offset 49" or "glibc detected double free or
458        corruption" errors.
460    27. Applied patches from Google (a) to support the new newline modes and (b) to
461        advance over multibyte UTF-8 characters in GlobalReplace.
463    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
464        difference for some implementation of PCRE in some Windows version.
466    29. Added some extra testing facilities to pcretest:
468        \q<number>   in a data line sets the "match limit" value
469        \Q<number>   in a data line sets the "match recursion limt" value
470        -S <number>  sets the stack size, where <number> is in megabytes
472        The -S option isn't available for Windows.
475  Version 6.6 06-Feb-06  Version 6.6 06-Feb-06
476  ---------------------  ---------------------

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