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

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