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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, for the benefit
30        of those who have to compile without Autotools (compare pcre.h).
31    
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.
36    
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.
40    
41     7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
42        that is needed.
43    
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.
50    
51    
52    Version 7.0 19-Dec-06
53    ---------------------
54    
55     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
56        moving to gcc 4.1.1.
57    
58     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
59        sys/time.h, which is documented as needed for this function. It doesn't
60        seem to matter on Linux, but it showed up on some releases of OS X.
61    
62     3. It seems that there are systems where bytes whose values are greater than
63        127 match isprint() in the "C" locale. The "C" locale should be the
64        default when a C program starts up. In most systems, only ASCII printing
65        characters match isprint(). This difference caused the output from pcretest
66        to vary, making some of the tests fail. I have changed pcretest so that:
67    
68        (a) When it is outputting text in the compiled version of a pattern, bytes
69            other than 32-126 are always shown as hex escapes.
70    
71        (b) When it is outputting text that is a matched part of a subject string,
72            it does the same, unless a different locale has been set for the match
73            (using the /L modifier). In this case, it uses isprint() to decide.
74    
75     4. Fixed a major bug that caused incorrect computation of the amount of memory
76        required for a compiled pattern when options that changed within the
77        pattern affected the logic of the preliminary scan that determines the
78        length. The relevant options are -x, and -i in UTF-8 mode. The result was
79        that the computed length was too small. The symptoms of this bug were
80        either the PCRE error "internal error: code overflow" from pcre_compile(),
81        or a glibc crash with a message such as "pcretest: free(): invalid next
82        size (fast)". Examples of patterns that provoked this bug (shown in
83        pcretest format) are:
84    
85          /(?-x: )/x
86          /(?x)(?-x: \s*#\s*)/
87          /((?i)[\x{c0}])/8
88          /(?i:[\x{c0}])/8
89    
90        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
91        is now done differently.
92    
93     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
94        wrapper classes; (b) implement a new function in the C++ scanner that is
95        more efficient than the old way of doing things because it avoids levels of
96        recursion in the regex matching; (c) add a paragraph to the documentation
97        for the FullMatch() function.
98    
99     6. The escape sequence \n was being treated as whatever was defined as
100        "newline". Not only was this contrary to the documentation, which states
101        that \n is character 10 (hex 0A), but it also went horribly wrong when
102        "newline" was defined as CRLF. This has been fixed.
103    
104     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
105        was being set to -1 for the "end of line" case (supposedly a value that no
106        character can have). Though this value is never used (the check for end of
107        line is "zero bytes in current character"), it caused compiler complaints.
108        I've changed it to 0xffffffff.
109    
110     8. In pcre_version.c, the version string was being built by a sequence of
111        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
112        string (as it is for production releases) called a macro with an empty
113        argument. The C standard says the result of this is undefined. The gcc
114        compiler treats it as an empty string (which was what was wanted) but it is
115        reported that Visual C gives an error. The source has been hacked around to
116        avoid this problem.
117    
118     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
119        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
120        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
121        of them did).
122    
123    10. Originally, pcretest opened its input and output without "b"; then I was
124        told that "b" was needed in some environments, so it was added for release
125        5.0 to both the input and output. (It makes no difference on Unix-like
126        systems.) Later I was told that it is wrong for the input on Windows. I've
127        now abstracted the modes into two macros, to make it easier to fiddle with
128        them, and removed "b" from the input mode under Windows.
129    
130    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
131    
132    12. Added -help and --help to pcretest as an official way of being reminded
133        of the options.
134    
135    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
136        and pcrecpp.cc because they annoy compilers at high warning levels.
137    
138    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
139    
140    15. Fixed an occurrence of == in configure.ac that should have been = (shell
141        scripts are not C programs :-) and which was not noticed because it works
142        on Linux.
143    
144    16. pcretest is supposed to handle any length of pattern and data line (as one
145        line or as a continued sequence of lines) by extending its input buffer if
146        necessary. This feature was broken for very long pattern lines, leading to
147        a string of junk being passed to pcre_compile() if the pattern was longer
148        than about 50K.
149    
150    17. I have done a major re-factoring of the way pcre_compile() computes the
151        amount of memory needed for a compiled pattern. Previously, there was code
152        that made a preliminary scan of the pattern in order to do this. That was
153        OK when PCRE was new, but as the facilities have expanded, it has become
154        harder and harder to keep it in step with the real compile phase, and there
155        have been a number of bugs (see for example, 4 above). I have now found a
156        cunning way of running the real compile function in a "fake" mode that
157        enables it to compute how much memory it would need, while actually only
158        ever using a few hundred bytes of working memory and without too many
159        tests of the mode. This should make future maintenance and development
160        easier. A side effect of this work is that the limit of 200 on the nesting
161        depth of parentheses has been removed (though this was never a serious
162        limitation, I suspect). However, there is a downside: pcre_compile() now
163        runs more slowly than before (30% or more, depending on the pattern). I
164        hope this isn't a big issue. There is no effect on runtime performance.
165    
166    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
167        newline (only possible for the last line of a file) and it was a
168        pattern that set a locale (followed by /Lsomething), pcretest crashed.
169    
170    19. Added additional timing features to pcretest. (1) The -tm option now times
171        matching only, not compiling. (2) Both -t and -tm can be followed, as a
172        separate command line item, by a number that specifies the number of
173        repeats to use when timing. The default is 50000; this gives better
174        precision, but takes uncomfortably long for very large patterns.
175    
176    20. Extended pcre_study() to be more clever in cases where a branch of a
177        subpattern has no definite first character. For example, (a*|b*)[cd] would
178        previously give no result from pcre_study(). Now it recognizes that the
179        first character must be a, b, c, or d.
180    
181    21. There was an incorrect error "recursive call could loop indefinitely" if
182        a subpattern (or the entire pattern) that was being tested for matching an
183        empty string contained only one non-empty item after a nested subpattern.
184        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
185        incorrectly, because the \d was being skipped in the check.
186    
187    22. The pcretest program now has a new pattern option /B and a command line
188        option -b, which is equivalent to adding /B to every pattern. This causes
189        it to show the compiled bytecode, without the additional information that
190        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
191        is the same as /B/I).
192    
193    23. A new optimization is now able automatically to treat some sequences such
194        as a*b as a*+b. More specifically, if something simple (such as a character
195        or a simple class like \d) has an unlimited quantifier, and is followed by
196        something that cannot possibly match the quantified thing, the quantifier
197        is automatically "possessified".
198    
199    24. A recursive reference to a subpattern whose number was greater than 39
200        went wrong under certain circumstances in UTF-8 mode. This bug could also
201        have affected the operation of pcre_study().
202    
203    25. Realized that a little bit of performance could be had by replacing
204        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
205    
206    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
207    
208    27. Possessive quantifiers such as a++ were previously implemented by turning
209        them into atomic groups such as ($>a+). Now they have their own opcodes,
210        which improves performance. This includes the automatically created ones
211        from 23 above.
212    
213    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
214        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
215        the first matched character to be a colon. This applied both to named and
216        numbered groups.
217    
218    29. The ucpinternal.h header file was missing its idempotency #ifdef.
219    
220    30. I was sent a "project" file called libpcre.a.dev which I understand makes
221        building PCRE on Windows easier, so I have included it in the distribution.
222    
223    31. There is now a check in pcretest against a ridiculously large number being
224        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
225        loop, the loop is abandoned.
226    
227    32. Forward references to subpatterns in conditions such as (?(2)...) where
228        subpattern 2 is defined later cause pcre_compile() to search forwards in
229        the pattern for the relevant set of parentheses. This search went wrong
230        when there were unescaped parentheses in a character class, parentheses
231        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
232    
233    33. "Subroutine" calls and backreferences were previously restricted to
234        referencing subpatterns earlier in the regex. This restriction has now
235        been removed.
236    
237    34. Added a number of extra features that are going to be in Perl 5.10. On the
238        whole, these are just syntactic alternatives for features that PCRE had
239        previously implemented using the Python syntax or my own invention. The
240        other formats are all retained for compatibility.
241    
242        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
243            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
244            also .NET compatible.
245    
246        (b) A recursion or subroutine call to a named group can now be defined as
247            (?&name) as well as (?P>name).
248    
249        (c) A backreference to a named group can now be defined as \k<name> or
250            \k'name' as well as (?P=name). The new forms, as well as being in Perl
251            5.10, are also .NET compatible.
252    
253        (d) A conditional reference to a named group can now use the syntax
254            (?(<name>) or (?('name') as well as (?(name).
255    
256        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
257            groups (named and numbered) that are never evaluated inline, but can be
258            called as "subroutines" from elsewhere. In effect, the DEFINE condition
259            is always false. There may be only one alternative in such a group.
260    
261        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
262            as the simple (?(R). The condition is true only if the most recent
263            recursion is that of the given number or name. It does not search out
264            through the entire recursion stack.
265    
266        (g) The escape \gN or \g{N} has been added, where N is a positive or
267            negative number, specifying an absolute or relative reference.
268    
269    35. Tidied to get rid of some further signed/unsigned compiler warnings and
270        some "unreachable code" warnings.
271    
272    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
273        things, this adds five new scripts.
274    
275    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
276        There were also incompatibilities regarding the handling of \Q..\E inside
277        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
278        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
279    
280    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
281        matches an empty string, and forcibly breaks the loop. There were bugs in
282        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
283        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
284        separate and independent bugs (that affected different cases) have been
285        fixed.
286    
287    39. Refactored the code to abolish the use of different opcodes for small
288        capturing bracket numbers. This is a tidy that I avoided doing when I
289        removed the limit on the number of capturing brackets for 3.5 back in 2001.
290        The new approach is not only tidier, it makes it possible to reduce the
291        memory needed to fix the previous bug (38).
292    
293    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
294        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
295        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
296        mode.
297    
298    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
299        report.
300    
301    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
302        copy construction and assignment in the C++ wrapper.
303    
304    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
305        couple of bugs that could have given wrong results in the "--newline=crlf"
306        case.
307    
308    44. Added a number of casts and did some reorganization of signed/unsigned int
309        variables following suggestions from Dair Grant. Also renamed the variable
310        "this" as "item" because it is a C++ keyword.
311    
312    45. Arranged for dftables to add
313    
314          #include "pcre_internal.h"
315    
316        to pcre_chartables.c because without it, gcc 4.x may remove the array
317        definition from the final binary if PCRE is built into a static library and
318        dead code stripping is activated.
319    
320    46. For an unanchored pattern, if a match attempt fails at the start of a
321        newline sequence, and the newline setting is CRLF or ANY, and the next two
322        characters are CRLF, advance by two characters instead of one.
323    
324    
325    Version 6.7 04-Jul-06
326    ---------------------
327    
328     1. In order to handle tests when input lines are enormously long, pcretest has
329        been re-factored so that it automatically extends its buffers when
330        necessary. The code is crude, but this _is_ just a test program. The
331        default size has been increased from 32K to 50K.
332    
333     2. The code in pcre_study() was using the value of the re argument before
334        testing it for NULL. (Of course, in any sensible call of the function, it
335        won't be NULL.)
336    
337     3. The memmove() emulation function in pcre_internal.h, which is used on
338        systems that lack both memmove() and bcopy() - that is, hardly ever -
339        was missing a "static" storage class specifier.
340    
341     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
342        containing an extended class (one that cannot be represented by a bitmap
343        because it contains high-valued characters or Unicode property items, e.g.
344        [\pZ]). Almost always one would set UTF-8 mode when processing such a
345        pattern, but PCRE should not loop if you do not (it no longer does).
346        [Detail: two cases were found: (a) a repeated subpattern containing an
347        extended class; (b) a recursive reference to a subpattern that followed a
348        previous extended class. It wasn't skipping over the extended class
349        correctly when UTF-8 mode was not set.]
350    
351     5. A negated single-character class was not being recognized as fixed-length
352        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
353        compile error "lookbehind assertion is not fixed length".
354    
355     6. The RunPerlTest auxiliary script was showing an unexpected difference
356        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
357        write a Perl script that can interpret lines of an input file either as
358        byte characters or as UTF-8, which is what "perltest" was being required to
359        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
360        can't do is switch easily at run time between having the "use utf8;" pragma
361        or not. In the end, I fudged it by using the RunPerlTest script to insert
362        "use utf8;" explicitly for the UTF-8 tests.
363    
364     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
365        the end of the subject string, contrary to the documentation and to what
366        Perl does. This was true of both matching functions. Now it matches only at
367        the start of the subject and immediately after *internal* newlines.
368    
369     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
370        a pointer to an int instead of a pointer to an unsigned long int. This
371        caused problems on 64-bit systems.
372    
373     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
374        instance of the 'standard' template library not being so standard".
375    
376    10. There was no check on the number of named subpatterns nor the maximum
377        length of a subpattern name. The product of these values is used to compute
378        the size of the memory block for a compiled pattern. By supplying a very
379        long subpattern name and a large number of named subpatterns, the size
380        computation could be caused to overflow. This is now prevented by limiting
381        the length of names to 32 characters, and the number of named subpatterns
382        to 10,000.
383    
384    11. Subpatterns that are repeated with specific counts have to be replicated in
385        the compiled pattern. The size of memory for this was computed from the
386        length of the subpattern and the repeat count. The latter is limited to
387        65535, but there was no limit on the former, meaning that integer overflow
388        could in principle occur. The compiled length of a repeated subpattern is
389        now limited to 30,000 bytes in order to prevent this.
390    
391    12. Added the optional facility to have named substrings with the same name.
392    
393    13. Added the ability to use a named substring as a condition, using the
394        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
395        are numbers (not recommended). Forward references are permitted.
396    
397    14. Added forward references in named backreferences (if you see what I mean).
398    
399    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
400        pattern could run off the end of the subject. For example, the pattern
401        "(?s)(.{1,5})"8 did this with the subject "ab".
402    
403    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
404        PCRE_CASELESS was set when matching characters that were quantified with ?
405        or *.
406    
407    17. A character class other than a single negated character that had a minimum
408        but no maximum quantifier - for example [ab]{6,} - was not handled
409        correctly by pce_dfa_exec(). It would match only one character.
410    
411    18. A valid (though odd) pattern that looked like a POSIX character
412        class but used an invalid character after [ (for example [[,abc,]]) caused
413        pcre_compile() to give the error "Failed: internal error: code overflow" or
414        in some cases to crash with a glibc free() error. This could even happen if
415        the pattern terminated after [[ but there just happened to be a sequence of
416        letters, a binary zero, and a closing ] in the memory that followed.
417    
418    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
419        over the years. Originally (before any Unicode support), just the bottom 8
420        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
421        output from "man perlunicode" includes this:
422    
423          The regular expression compiler produces polymorphic opcodes.  That
424          is, the pattern adapts to the data and automatically switches to
425          the Unicode character scheme when presented with Unicode data--or
426          instead uses a traditional byte scheme when presented with byte
427          data.
428    
429        Sadly, a wide octal escape does not cause a switch, and in a string with
430        no other multibyte characters, these octal escapes are treated as before.
431        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
432        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
433        Unicode string.
434    
435        I have not perpetrated such confusion in PCRE. Up till now, it took just
436        the bottom 8 bits, as in old Perl. I have now made octal escapes with
437        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
438        translate to the appropriate multibyte character.
439    
440    29. Applied some refactoring to reduce the number of warnings from Microsoft
441        and Borland compilers. This has included removing the fudge introduced
442        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
443        a warning about an unused variable.
444    
445    21. PCRE has not included VT (character 0x0b) in the set of whitespace
446        characters since release 4.0, because Perl (from release 5.004) does not.
447        [Or at least, is documented not to: some releases seem to be in conflict
448        with the documentation.] However, when a pattern was studied with
449        pcre_study() and all its branches started with \s, PCRE still included VT
450        as a possible starting character. Of course, this did no harm; it just
451        caused an unnecessary match attempt.
452    
453    22. Removed a now-redundant internal flag bit that recorded the fact that case
454        dependency changed within the pattern. This was once needed for "required
455        byte" processing, but is no longer used. This recovers a now-scarce options
456        bit. Also moved the least significant internal flag bit to the most-
457        significant bit of the word, which was not previously used (hangover from
458        the days when it was an int rather than a uint) to free up another bit for
459        the future.
460    
461    23. Added support for CRLF line endings as well as CR and LF. As well as the
462        default being selectable at build time, it can now be changed at runtime
463        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
464        specify that it is scanning data with non-default line endings.
465    
466    24. Changed the definition of CXXLINK to make it agree with the definition of
467        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
468    
469    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
470        recursions. This makes a big different to stack usage for some patterns.
471    
472    26. If a subpattern containing a named recursion or subroutine reference such
473        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
474        the space required for the compiled pattern went wrong and gave too small a
475        value. Depending on the environment, this could lead to "Failed: internal
476        error: code overflow at offset 49" or "glibc detected double free or
477        corruption" errors.
478    
479    27. Applied patches from Google (a) to support the new newline modes and (b) to
480        advance over multibyte UTF-8 characters in GlobalReplace.
481    
482    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
483        difference for some implementation of PCRE in some Windows version.
484    
485    29. Added some extra testing facilities to pcretest:
486    
487        \q<number>   in a data line sets the "match limit" value
488        \Q<number>   in a data line sets the "match recursion limt" value
489        -S <number>  sets the stack size, where <number> is in megabytes
490    
491        The -S option isn't available for Windows.
492    
493    
494    Version 6.6 06-Feb-06
495    ---------------------
496    
497     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
498        in pcreposix.h. I have copied the definition from pcre.h.
499    
500     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
501        because pcre.h is no longer a built file.
502    
503     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
504        not normally included in the compiled code.
505    
506    
507  Version 6.5 01-Feb-06  Version 6.5 01-Feb-06
508  ---------------------  ---------------------
509    

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