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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    
45    Version 7.0 19-Dec-06
46    ---------------------
47    
48     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
49        moving to gcc 4.1.1.
50    
51     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
52        sys/time.h, which is documented as needed for this function. It doesn't
53        seem to matter on Linux, but it showed up on some releases of OS X.
54    
55     3. It seems that there are systems where bytes whose values are greater than
56        127 match isprint() in the "C" locale. The "C" locale should be the
57        default when a C program starts up. In most systems, only ASCII printing
58        characters match isprint(). This difference caused the output from pcretest
59        to vary, making some of the tests fail. I have changed pcretest so that:
60    
61        (a) When it is outputting text in the compiled version of a pattern, bytes
62            other than 32-126 are always shown as hex escapes.
63    
64        (b) When it is outputting text that is a matched part of a subject string,
65            it does the same, unless a different locale has been set for the match
66            (using the /L modifier). In this case, it uses isprint() to decide.
67    
68     4. Fixed a major bug that caused incorrect computation of the amount of memory
69        required for a compiled pattern when options that changed within the
70        pattern affected the logic of the preliminary scan that determines the
71        length. The relevant options are -x, and -i in UTF-8 mode. The result was
72        that the computed length was too small. The symptoms of this bug were
73        either the PCRE error "internal error: code overflow" from pcre_compile(),
74        or a glibc crash with a message such as "pcretest: free(): invalid next
75        size (fast)". Examples of patterns that provoked this bug (shown in
76        pcretest format) are:
77    
78          /(?-x: )/x
79          /(?x)(?-x: \s*#\s*)/
80          /((?i)[\x{c0}])/8
81          /(?i:[\x{c0}])/8
82    
83        HOWEVER: Change 17 below makes this fix obsolete as the memory computation
84        is now done differently.
85    
86     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
87        wrapper classes; (b) implement a new function in the C++ scanner that is
88        more efficient than the old way of doing things because it avoids levels of
89        recursion in the regex matching; (c) add a paragraph to the documentation
90        for the FullMatch() function.
91    
92     6. The escape sequence \n was being treated as whatever was defined as
93        "newline". Not only was this contrary to the documentation, which states
94        that \n is character 10 (hex 0A), but it also went horribly wrong when
95        "newline" was defined as CRLF. This has been fixed.
96    
97     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
98        was being set to -1 for the "end of line" case (supposedly a value that no
99        character can have). Though this value is never used (the check for end of
100        line is "zero bytes in current character"), it caused compiler complaints.
101        I've changed it to 0xffffffff.
102    
103     8. In pcre_version.c, the version string was being built by a sequence of
104        C macros that, in the event of PCRE_PRERELEASE being defined as an empty
105        string (as it is for production releases) called a macro with an empty
106        argument. The C standard says the result of this is undefined. The gcc
107        compiler treats it as an empty string (which was what was wanted) but it is
108        reported that Visual C gives an error. The source has been hacked around to
109        avoid this problem.
110    
111     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
112        builds of pcretest, and changed the call to _setmode() to use _O_BINARY
113        instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
114        of them did).
115    
116    10. Originally, pcretest opened its input and output without "b"; then I was
117        told that "b" was needed in some environments, so it was added for release
118        5.0 to both the input and output. (It makes no difference on Unix-like
119        systems.) Later I was told that it is wrong for the input on Windows. I've
120        now abstracted the modes into two macros, to make it easier to fiddle with
121        them, and removed "b" from the input mode under Windows.
122    
123    11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
124    
125    12. Added -help and --help to pcretest as an official way of being reminded
126        of the options.
127    
128    13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
129        and pcrecpp.cc because they annoy compilers at high warning levels.
130    
131    14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
132    
133    15. Fixed an occurrence of == in configure.ac that should have been = (shell
134        scripts are not C programs :-) and which was not noticed because it works
135        on Linux.
136    
137    16. pcretest is supposed to handle any length of pattern and data line (as one
138        line or as a continued sequence of lines) by extending its input buffer if
139        necessary. This feature was broken for very long pattern lines, leading to
140        a string of junk being passed to pcre_compile() if the pattern was longer
141        than about 50K.
142    
143    17. I have done a major re-factoring of the way pcre_compile() computes the
144        amount of memory needed for a compiled pattern. Previously, there was code
145        that made a preliminary scan of the pattern in order to do this. That was
146        OK when PCRE was new, but as the facilities have expanded, it has become
147        harder and harder to keep it in step with the real compile phase, and there
148        have been a number of bugs (see for example, 4 above). I have now found a
149        cunning way of running the real compile function in a "fake" mode that
150        enables it to compute how much memory it would need, while actually only
151        ever using a few hundred bytes of working memory and without too many
152        tests of the mode. This should make future maintenance and development
153        easier. A side effect of this work is that the limit of 200 on the nesting
154        depth of parentheses has been removed (though this was never a serious
155        limitation, I suspect). However, there is a downside: pcre_compile() now
156        runs more slowly than before (30% or more, depending on the pattern). I
157        hope this isn't a big issue. There is no effect on runtime performance.
158    
159    18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
160        newline (only possible for the last line of a file) and it was a
161        pattern that set a locale (followed by /Lsomething), pcretest crashed.
162    
163    19. Added additional timing features to pcretest. (1) The -tm option now times
164        matching only, not compiling. (2) Both -t and -tm can be followed, as a
165        separate command line item, by a number that specifies the number of
166        repeats to use when timing. The default is 50000; this gives better
167        precision, but takes uncomfortably long for very large patterns.
168    
169    20. Extended pcre_study() to be more clever in cases where a branch of a
170        subpattern has no definite first character. For example, (a*|b*)[cd] would
171        previously give no result from pcre_study(). Now it recognizes that the
172        first character must be a, b, c, or d.
173    
174    21. There was an incorrect error "recursive call could loop indefinitely" if
175        a subpattern (or the entire pattern) that was being tested for matching an
176        empty string contained only one non-empty item after a nested subpattern.
177        For example, the pattern (?>\x{100}*)\d(?R) provoked this error
178        incorrectly, because the \d was being skipped in the check.
179    
180    22. The pcretest program now has a new pattern option /B and a command line
181        option -b, which is equivalent to adding /B to every pattern. This causes
182        it to show the compiled bytecode, without the additional information that
183        -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
184        is the same as /B/I).
185    
186    23. A new optimization is now able automatically to treat some sequences such
187        as a*b as a*+b. More specifically, if something simple (such as a character
188        or a simple class like \d) has an unlimited quantifier, and is followed by
189        something that cannot possibly match the quantified thing, the quantifier
190        is automatically "possessified".
191    
192    24. A recursive reference to a subpattern whose number was greater than 39
193        went wrong under certain circumstances in UTF-8 mode. This bug could also
194        have affected the operation of pcre_study().
195    
196    25. Realized that a little bit of performance could be had by replacing
197        (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
198    
199    26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
200    
201    27. Possessive quantifiers such as a++ were previously implemented by turning
202        them into atomic groups such as ($>a+). Now they have their own opcodes,
203        which improves performance. This includes the automatically created ones
204        from 23 above.
205    
206    28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
207        lookahead was broken if it was not anchored. PCRE was mistakenly expecting
208        the first matched character to be a colon. This applied both to named and
209        numbered groups.
210    
211    29. The ucpinternal.h header file was missing its idempotency #ifdef.
212    
213    30. I was sent a "project" file called libpcre.a.dev which I understand makes
214        building PCRE on Windows easier, so I have included it in the distribution.
215    
216    31. There is now a check in pcretest against a ridiculously large number being
217        returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
218        loop, the loop is abandoned.
219    
220    32. Forward references to subpatterns in conditions such as (?(2)...) where
221        subpattern 2 is defined later cause pcre_compile() to search forwards in
222        the pattern for the relevant set of parentheses. This search went wrong
223        when there were unescaped parentheses in a character class, parentheses
224        escaped with \Q...\E, or parentheses in a #-comment in /x mode.
225    
226    33. "Subroutine" calls and backreferences were previously restricted to
227        referencing subpatterns earlier in the regex. This restriction has now
228        been removed.
229    
230    34. Added a number of extra features that are going to be in Perl 5.10. On the
231        whole, these are just syntactic alternatives for features that PCRE had
232        previously implemented using the Python syntax or my own invention. The
233        other formats are all retained for compatibility.
234    
235        (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
236            as (?P<name>...). The new forms, as well as being in Perl 5.10, are
237            also .NET compatible.
238    
239        (b) A recursion or subroutine call to a named group can now be defined as
240            (?&name) as well as (?P>name).
241    
242        (c) A backreference to a named group can now be defined as \k<name> or
243            \k'name' as well as (?P=name). The new forms, as well as being in Perl
244            5.10, are also .NET compatible.
245    
246        (d) A conditional reference to a named group can now use the syntax
247            (?(<name>) or (?('name') as well as (?(name).
248    
249        (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
250            groups (named and numbered) that are never evaluated inline, but can be
251            called as "subroutines" from elsewhere. In effect, the DEFINE condition
252            is always false. There may be only one alternative in such a group.
253    
254        (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
255            as the simple (?(R). The condition is true only if the most recent
256            recursion is that of the given number or name. It does not search out
257            through the entire recursion stack.
258    
259        (g) The escape \gN or \g{N} has been added, where N is a positive or
260            negative number, specifying an absolute or relative reference.
261    
262    35. Tidied to get rid of some further signed/unsigned compiler warnings and
263        some "unreachable code" warnings.
264    
265    36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
266        things, this adds five new scripts.
267    
268    37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
269        There were also incompatibilities regarding the handling of \Q..\E inside
270        character classes, for example with patterns like [\Qa\E-\Qz\E] where the
271        hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
272    
273    38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
274        matches an empty string, and forcibly breaks the loop. There were bugs in
275        this code in non-simple cases. For a pattern such as  ^(a()*)*  matched
276        against  aaaa  the result was just "a" rather than "aaaa", for example. Two
277        separate and independent bugs (that affected different cases) have been
278        fixed.
279    
280    39. Refactored the code to abolish the use of different opcodes for small
281        capturing bracket numbers. This is a tidy that I avoided doing when I
282        removed the limit on the number of capturing brackets for 3.5 back in 2001.
283        The new approach is not only tidier, it makes it possible to reduce the
284        memory needed to fix the previous bug (38).
285    
286    40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
287        sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
288        processing dot, circumflex, or dollar metacharacters, or #-comments in /x
289        mode.
290    
291    41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
292        report.
293    
294    42. Applied patch, originally from Ari Pollak, modified by Google, to allow
295        copy construction and assignment in the C++ wrapper.
296    
297    43. Updated pcregrep to support "--newline=any". In the process, I fixed a
298        couple of bugs that could have given wrong results in the "--newline=crlf"
299        case.
300    
301    44. Added a number of casts and did some reorganization of signed/unsigned int
302        variables following suggestions from Dair Grant. Also renamed the variable
303        "this" as "item" because it is a C++ keyword.
304    
305    45. Arranged for dftables to add
306    
307          #include "pcre_internal.h"
308    
309        to pcre_chartables.c because without it, gcc 4.x may remove the array
310        definition from the final binary if PCRE is built into a static library and
311        dead code stripping is activated.
312    
313    46. For an unanchored pattern, if a match attempt fails at the start of a
314        newline sequence, and the newline setting is CRLF or ANY, and the next two
315        characters are CRLF, advance by two characters instead of one.
316    
317    
318    Version 6.7 04-Jul-06
319    ---------------------
320    
321     1. In order to handle tests when input lines are enormously long, pcretest has
322        been re-factored so that it automatically extends its buffers when
323        necessary. The code is crude, but this _is_ just a test program. The
324        default size has been increased from 32K to 50K.
325    
326     2. The code in pcre_study() was using the value of the re argument before
327        testing it for NULL. (Of course, in any sensible call of the function, it
328        won't be NULL.)
329    
330     3. The memmove() emulation function in pcre_internal.h, which is used on
331        systems that lack both memmove() and bcopy() - that is, hardly ever -
332        was missing a "static" storage class specifier.
333    
334     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
335        containing an extended class (one that cannot be represented by a bitmap
336        because it contains high-valued characters or Unicode property items, e.g.
337        [\pZ]). Almost always one would set UTF-8 mode when processing such a
338        pattern, but PCRE should not loop if you do not (it no longer does).
339        [Detail: two cases were found: (a) a repeated subpattern containing an
340        extended class; (b) a recursive reference to a subpattern that followed a
341        previous extended class. It wasn't skipping over the extended class
342        correctly when UTF-8 mode was not set.]
343    
344     5. A negated single-character class was not being recognized as fixed-length
345        in lookbehind assertions such as (?<=[^f]), leading to an incorrect
346        compile error "lookbehind assertion is not fixed length".
347    
348     6. The RunPerlTest auxiliary script was showing an unexpected difference
349        between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
350        write a Perl script that can interpret lines of an input file either as
351        byte characters or as UTF-8, which is what "perltest" was being required to
352        do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
353        can't do is switch easily at run time between having the "use utf8;" pragma
354        or not. In the end, I fudged it by using the RunPerlTest script to insert
355        "use utf8;" explicitly for the UTF-8 tests.
356    
357     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
358        the end of the subject string, contrary to the documentation and to what
359        Perl does. This was true of both matching functions. Now it matches only at
360        the start of the subject and immediately after *internal* newlines.
361    
362     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
363        a pointer to an int instead of a pointer to an unsigned long int. This
364        caused problems on 64-bit systems.
365    
366     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
367        instance of the 'standard' template library not being so standard".
368    
369    10. There was no check on the number of named subpatterns nor the maximum
370        length of a subpattern name. The product of these values is used to compute
371        the size of the memory block for a compiled pattern. By supplying a very
372        long subpattern name and a large number of named subpatterns, the size
373        computation could be caused to overflow. This is now prevented by limiting
374        the length of names to 32 characters, and the number of named subpatterns
375        to 10,000.
376    
377    11. Subpatterns that are repeated with specific counts have to be replicated in
378        the compiled pattern. The size of memory for this was computed from the
379        length of the subpattern and the repeat count. The latter is limited to
380        65535, but there was no limit on the former, meaning that integer overflow
381        could in principle occur. The compiled length of a repeated subpattern is
382        now limited to 30,000 bytes in order to prevent this.
383    
384    12. Added the optional facility to have named substrings with the same name.
385    
386    13. Added the ability to use a named substring as a condition, using the
387        Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
388        are numbers (not recommended). Forward references are permitted.
389    
390    14. Added forward references in named backreferences (if you see what I mean).
391    
392    15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
393        pattern could run off the end of the subject. For example, the pattern
394        "(?s)(.{1,5})"8 did this with the subject "ab".
395    
396    16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
397        PCRE_CASELESS was set when matching characters that were quantified with ?
398        or *.
399    
400    17. A character class other than a single negated character that had a minimum
401        but no maximum quantifier - for example [ab]{6,} - was not handled
402        correctly by pce_dfa_exec(). It would match only one character.
403    
404    18. A valid (though odd) pattern that looked like a POSIX character
405        class but used an invalid character after [ (for example [[,abc,]]) caused
406        pcre_compile() to give the error "Failed: internal error: code overflow" or
407        in some cases to crash with a glibc free() error. This could even happen if
408        the pattern terminated after [[ but there just happened to be a sequence of
409        letters, a binary zero, and a closing ] in the memory that followed.
410    
411    19. Perl's treatment of octal escapes in the range \400 to \777 has changed
412        over the years. Originally (before any Unicode support), just the bottom 8
413        bits were taken. Thus, for example, \500 really meant \100. Nowadays the
414        output from "man perlunicode" includes this:
415    
416          The regular expression compiler produces polymorphic opcodes.  That
417          is, the pattern adapts to the data and automatically switches to
418          the Unicode character scheme when presented with Unicode data--or
419          instead uses a traditional byte scheme when presented with byte
420          data.
421    
422        Sadly, a wide octal escape does not cause a switch, and in a string with
423        no other multibyte characters, these octal escapes are treated as before.
424        Thus, in Perl, the pattern  /\500/ actually matches \100 but the pattern
425        /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
426        Unicode string.
427    
428        I have not perpetrated such confusion in PCRE. Up till now, it took just
429        the bottom 8 bits, as in old Perl. I have now made octal escapes with
430        values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
431        translate to the appropriate multibyte character.
432    
433    29. Applied some refactoring to reduce the number of warnings from Microsoft
434        and Borland compilers. This has included removing the fudge introduced
435        seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
436        a warning about an unused variable.
437    
438    21. PCRE has not included VT (character 0x0b) in the set of whitespace
439        characters since release 4.0, because Perl (from release 5.004) does not.
440        [Or at least, is documented not to: some releases seem to be in conflict
441        with the documentation.] However, when a pattern was studied with
442        pcre_study() and all its branches started with \s, PCRE still included VT
443        as a possible starting character. Of course, this did no harm; it just
444        caused an unnecessary match attempt.
445    
446    22. Removed a now-redundant internal flag bit that recorded the fact that case
447        dependency changed within the pattern. This was once needed for "required
448        byte" processing, but is no longer used. This recovers a now-scarce options
449        bit. Also moved the least significant internal flag bit to the most-
450        significant bit of the word, which was not previously used (hangover from
451        the days when it was an int rather than a uint) to free up another bit for
452        the future.
453    
454    23. Added support for CRLF line endings as well as CR and LF. As well as the
455        default being selectable at build time, it can now be changed at runtime
456        via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
457        specify that it is scanning data with non-default line endings.
458    
459    24. Changed the definition of CXXLINK to make it agree with the definition of
460        LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
461    
462    25. Applied Ian Taylor's patches to avoid using another stack frame for tail
463        recursions. This makes a big different to stack usage for some patterns.
464    
465    26. If a subpattern containing a named recursion or subroutine reference such
466        as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
467        the space required for the compiled pattern went wrong and gave too small a
468        value. Depending on the environment, this could lead to "Failed: internal
469        error: code overflow at offset 49" or "glibc detected double free or
470        corruption" errors.
471    
472    27. Applied patches from Google (a) to support the new newline modes and (b) to
473        advance over multibyte UTF-8 characters in GlobalReplace.
474    
475    28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
476        difference for some implementation of PCRE in some Windows version.
477    
478    29. Added some extra testing facilities to pcretest:
479    
480        \q<number>   in a data line sets the "match limit" value
481        \Q<number>   in a data line sets the "match recursion limt" value
482        -S <number>  sets the stack size, where <number> is in megabytes
483    
484        The -S option isn't available for Windows.
485    
486    
487    Version 6.6 06-Feb-06
488    ---------------------
489    
490     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
491        in pcreposix.h. I have copied the definition from pcre.h.
492    
493     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
494        because pcre.h is no longer a built file.
495    
496     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
497        not normally included in the compiled code.
498    
499    
500  Version 6.5 01-Feb-06  Version 6.5 01-Feb-06
501  ---------------------  ---------------------
502    

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