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Revision 291 - (hide annotations) (download)
Wed Dec 26 18:46:46 2007 UTC (6 years, 11 months ago) by ph10
File size: 146814 byte(s)
Update CMake files for new build-arguments.

1 nigel 3 ChangeLog for PCRE
2     ------------------
3    
4 ph10 289 Version 7.5 23-Dec-07
5 ph10 263 ---------------------
6    
7     1. Applied a patch from Craig: "This patch makes it possible to 'ignore'
8     values in parens when parsing an RE using the C++ wrapper."
9 ph10 286
10 ph10 264 2. Negative specials like \S did not work in character classes in UTF-8 mode.
11     Characters greater than 255 were excluded from the class instead of being
12     included.
13 ph10 286
14     3. The same bug as (2) above applied to negated POSIX classes such as
15 ph10 265 [:^space:].
16 ph10 286
17 ph10 267 4. PCRECPP_STATIC was referenced in pcrecpp_internal.h, but nowhere was it
18     defined or documented. It seems to have been a typo for PCRE_STATIC, so
19 ph10 286 I have changed it.
20    
21 ph10 268 5. The construct (?&) was not diagnosed as a syntax error (it referenced the
22 ph10 286 first named subpattern) and a construct such as (?&a) would reference the
23     first named subpattern whose name started with "a" (in other words, the
24 ph10 272 length check was missing). Both these problems are fixed. "Subpattern name
25     expected" is now given for (?&) (a zero-length name), and this patch also
26     makes it give the same error for \k'' (previously it complained that that
27     was a reference to a non-existent subpattern).
28 ph10 286
29 ph10 269 6. The erroneous patterns (?+-a) and (?-+a) give different error messages;
30 ph10 286 this is right because (?- can be followed by option settings as well as by
31 ph10 269 digits. I have, however, made the messages clearer.
32 ph10 286
33 ph10 270 7. Patterns such as (?(1)a|b) (a pattern that contains fewer subpatterns
34     than the number used in the conditional) now cause a compile-time error.
35     This is actually not compatible with Perl, which accepts such patterns, but
36     treats the conditional as always being FALSE (as PCRE used to), but it
37     seems to me that giving a diagnostic is better.
38 ph10 286
39 ph10 274 8. Change "alphameric" to the more common word "alphanumeric" in comments
40 ph10 275 and messages.
41 ph10 286
42     9. Fix two occurrences of "backslash" in comments that should have been
43     "backspace".
44    
45     10. Remove two redundant lines of code that can never be obeyed (their function
46     was moved elsewhere).
47    
48     11. The program that makes PCRE's Unicode character property table had a bug
49     which caused it to generate incorrect table entries for sequences of
50 ph10 277 characters that have the same character type, but are in different scripts.
51 ph10 286 It amalgamated them into a single range, with the script of the first of
52 ph10 277 them. In other words, some characters were in the wrong script. There were
53     thirteen such cases, affecting characters in the following ranges:
54 ph10 286
55 ph10 277 U+002b0 - U+002c1
56     U+0060c - U+0060d
57 ph10 286 U+0061e - U+00612
58 ph10 277 U+0064b - U+0065e
59     U+0074d - U+0076d
60     U+01800 - U+01805
61     U+01d00 - U+01d77
62     U+01d9b - U+01dbf
63     U+0200b - U+0200f
64     U+030fc - U+030fe
65     U+03260 - U+0327f
66     U+0fb46 - U+0fbb1
67     U+10450 - U+1049d
68 ph10 286
69 ph10 279 12. The -o option (show only the matching part of a line) for pcregrep was not
70     compatible with GNU grep in that, if there was more than one match in a
71     line, it showed only the first of them. It now behaves in the same way as
72     GNU grep.
73 ph10 286
74     13. If the -o and -v options were combined for pcregrep, it printed a blank
75     line for every non-matching line. GNU grep prints nothing, and pcregrep now
76     does the same. The return code can be used to tell if there were any
77     non-matching lines.
78    
79 ph10 289 14. Added --file-offsets and --line-offsets to pcregrep.
80    
81     15. The pattern (?=something)(?R) was not being diagnosed as a potentially
82 ph10 282 infinitely looping recursion. The bug was that positive lookaheads were not
83 ph10 286 being skipped when checking for a possible empty match (negative lookaheads
84     and both kinds of lookbehind were skipped).
85    
86 ph10 289 16. Fixed two typos in the Windows-only code in pcregrep.c, and moved the
87 ph10 284 inclusion of <windows.h> to before rather than after the definition of
88     INVALID_FILE_ATTRIBUTES (patch from David Byron).
89 ph10 263
90 ph10 289 17. Specifying a possessive quantifier with a specific limit for a Unicode
91 ph10 286 character property caused pcre_compile() to compile bad code, which led at
92     runtime to PCRE_ERROR_INTERNAL (-14). Examples of patterns that caused this
93     are: /\p{Zl}{2,3}+/8 and /\p{Cc}{2}+/8. It was the possessive "+" that
94     caused the error; without that there was no problem.
95 ph10 263
96 ph10 289 18. Added --enable-pcregrep-libz and --enable-pcregrep-libbz2.
97 ph10 286
98 ph10 289 19. Added --enable-pcretest-libreadline.
99 ph10 286
100 ph10 289 20. In pcrecpp.cc, the variable 'count' was incremented twice in
101 ph10 288 RE::GlobalReplace(). As a result, the number of replacements returned was
102     double what it should be. I have removed one of the increments.
103 ph10 291
104     21. Several CMake things:
105 ph10 287
106 ph10 291 (1) Arranged that, when cmake is used on Unix, the libraries end up with
107     the names libpcre and libpcreposix.
108    
109     (2) Arranged for pcretest and pcregrep to link with the newly-built
110     libraries, not previously installed ones.
111    
112     (3) Added PCRE_SUPPORT_LIBREADLINE, PCRE_SUPPORT_LIBZ, PCRE_SUPPORT_LIBBZ2.
113 ph10 288
114 ph10 291
115 ph10 260 Version 7.4 21-Sep-07
116 ph10 230 ---------------------
117    
118     1. Change 7.3/28 was implemented for classes by looking at the bitmap. This
119 ph10 231 means that a class such as [\s] counted as "explicit reference to CR or
120     LF". That isn't really right - the whole point of the change was to try to
121     help when there was an actual mention of one of the two characters. So now
122     the change happens only if \r or \n (or a literal CR or LF) character is
123 ph10 230 encountered.
124 ph10 231
125     2. The 32-bit options word was also used for 6 internal flags, but the numbers
126     of both had grown to the point where there were only 3 bits left.
127     Fortunately, there was spare space in the data structure, and so I have
128     moved the internal flags into a new 16-bit field to free up more option
129 ph10 230 bits.
130 ph10 231
131     3. The appearance of (?J) at the start of a pattern set the DUPNAMES option,
132     but did not set the internal JCHANGED flag - either of these is enough to
133     control the way the "get" function works - but the PCRE_INFO_JCHANGED
134     facility is supposed to tell if (?J) was ever used, so now (?J) at the
135 ph10 230 start sets both bits.
136    
137 ph10 231 4. Added options (at build time, compile time, exec time) to change \R from
138     matching any Unicode line ending sequence to just matching CR, LF, or CRLF.
139 ph10 230
140 ph10 243 5. doc/pcresyntax.html was missing from the distribution.
141    
142     6. Put back the definition of PCRE_ERROR_NULLWSLIMIT, for backward
143 ph10 233 compatibility, even though it is no longer used.
144 ph10 243
145     7. Added macro for snprintf to pcrecpp_unittest.cc and also for strtoll and
146 ph10 254 strtoull to pcrecpp.cc to select the available functions in WIN32 when the
147 ph10 259 windows.h file is present (where different names are used). [This was
148 ph10 257 reversed later after testing - see 16 below.]
149 ph10 243
150     8. Changed all #include <config.h> to #include "config.h". There were also
151 ph10 236 some further <pcre.h> cases that I changed to "pcre.h".
152 ph10 243
153 ph10 239 9. When pcregrep was used with the --colour option, it missed the line ending
154 ph10 243 sequence off the lines that it output.
155    
156     10. It was pointed out to me that arrays of string pointers cause lots of
157     relocations when a shared library is dynamically loaded. A technique of
158     using a single long string with a table of offsets can drastically reduce
159     these. I have refactored PCRE in four places to do this. The result is
160 ph10 240 dramatic:
161 ph10 243
162 ph10 240 Originally: 290
163     After changing UCP table: 187
164 ph10 243 After changing error message table: 43
165 ph10 240 After changing table of "verbs" 36
166     After changing table of Posix names 22
167 ph10 243
168 ph10 240 Thanks to the folks working on Gregex for glib for this insight.
169 ph10 247
170 ph10 244 11. --disable-stack-for-recursion caused compiling to fail unless -enable-
171 ph10 247 unicode-properties was also set.
172    
173 ph10 248 12. Updated the tests so that they work when \R is defaulted to ANYCRLF.
174 ph10 231
175 ph10 253 13. Added checks for ANY and ANYCRLF to pcrecpp.cc where it previously
176     checked only for CRLF.
177 ph10 233
178 ph10 259 14. Added casts to pcretest.c to avoid compiler warnings.
179    
180 ph10 256 15. Added Craig's patch to various pcrecpp modules to avoid compiler warnings.
181 ph10 253
182 ph10 257 16. Added Craig's patch to remove the WINDOWS_H tests, that were not working,
183 ph10 259 and instead check for _strtoi64 explicitly, and avoid the use of snprintf()
184     entirely. This removes changes made in 7 above.
185 ph10 256
186 ph10 261 17. The CMake files have been updated, and there is now more information about
187     building with CMake in the NON-UNIX-USE document.
188 ph10 257
189 ph10 261
190 ph10 228 Version 7.3 28-Aug-07
191 ph10 157 ---------------------
192    
193 ph10 189 1. In the rejigging of the build system that eventually resulted in 7.1, the
194     line "#include <pcre.h>" was included in pcre_internal.h. The use of angle
195     brackets there is not right, since it causes compilers to look for an
196     installed pcre.h, not the version that is in the source that is being
197     compiled (which of course may be different). I have changed it back to:
198 ph10 197
199 ph10 189 #include "pcre.h"
200 ph10 197
201     I have a vague recollection that the change was concerned with compiling in
202     different directories, but in the new build system, that is taken care of
203     by the VPATH setting the Makefile.
204    
205 ph10 190 2. The pattern .*$ when run in not-DOTALL UTF-8 mode with newline=any failed
206     when the subject happened to end in the byte 0x85 (e.g. if the last
207     character was \x{1ec5}). *Character* 0x85 is one of the "any" newline
208     characters but of course it shouldn't be taken as a newline when it is part
209     of another character. The bug was that, for an unlimited repeat of . in
210     not-DOTALL UTF-8 mode, PCRE was advancing by bytes rather than by
211     characters when looking for a newline.
212 ph10 197
213     3. A small performance improvement in the DOTALL UTF-8 mode .* case.
214    
215     4. Debugging: adjusted the names of opcodes for different kinds of parentheses
216     in debug output.
217    
218 ph10 201 5. Arrange to use "%I64d" instead of "%lld" and "%I64u" instead of "%llu" for
219     long printing in the pcrecpp unittest when running under MinGW.
220 ph10 189
221 ph10 197 6. ESC_K was left out of the EBCDIC table.
222 ph10 189
223 ph10 197 7. Change 7.0/38 introduced a new limit on the number of nested non-capturing
224     parentheses; I made it 1000, which seemed large enough. Unfortunately, the
225     limit also applies to "virtual nesting" when a pattern is recursive, and in
226     this case 1000 isn't so big. I have been able to remove this limit at the
227     expense of backing off one optimization in certain circumstances. Normally,
228     when pcre_exec() would call its internal match() function recursively and
229     immediately return the result unconditionally, it uses a "tail recursion"
230     feature to save stack. However, when a subpattern that can match an empty
231     string has an unlimited repetition quantifier, it no longer makes this
232     optimization. That gives it a stack frame in which to save the data for
233     checking that an empty string has been matched. Previously this was taken
234     from the 1000-entry workspace that had been reserved. So now there is no
235     explicit limit, but more stack is used.
236 ph10 189
237 ph10 200 8. Applied Daniel's patches to solve problems with the import/export magic
238     syntax that is required for Windows, and which was going wrong for the
239     pcreposix and pcrecpp parts of the library. These were overlooked when this
240     problem was solved for the main library.
241 ph10 197
242 ph10 202 9. There were some crude static tests to avoid integer overflow when computing
243     the size of patterns that contain repeated groups with explicit upper
244     limits. As the maximum quantifier is 65535, the maximum group length was
245     set at 30,000 so that the product of these two numbers did not overflow a
246     32-bit integer. However, it turns out that people want to use groups that
247     are longer than 30,000 bytes (though not repeat them that many times).
248     Change 7.0/17 (the refactoring of the way the pattern size is computed) has
249     made it possible to implement the integer overflow checks in a much more
250     dynamic way, which I have now done. The artificial limitation on group
251     length has been removed - we now have only the limit on the total length of
252     the compiled pattern, which depends on the LINK_SIZE setting.
253 ph10 208
254     10. Fixed a bug in the documentation for get/copy named substring when
255     duplicate names are permitted. If none of the named substrings are set, the
256     functions return PCRE_ERROR_NOSUBSTRING (7); the doc said they returned an
257     empty string.
258    
259     11. Because Perl interprets \Q...\E at a high level, and ignores orphan \E
260     instances, patterns such as [\Q\E] or [\E] or even [^\E] cause an error,
261     because the ] is interpreted as the first data character and the
262     terminating ] is not found. PCRE has been made compatible with Perl in this
263     regard. Previously, it interpreted [\Q\E] as an empty class, and [\E] could
264     cause memory overwriting.
265    
266 ph10 206 10. Like Perl, PCRE automatically breaks an unlimited repeat after an empty
267     string has been matched (to stop an infinite loop). It was not recognizing
268 ph10 208 a conditional subpattern that could match an empty string if that
269 ph10 206 subpattern was within another subpattern. For example, it looped when
270 ph10 208 trying to match (((?(1)X|))*) but it was OK with ((?(1)X|)*) where the
271 ph10 206 condition was not nested. This bug has been fixed.
272 ph10 208
273 ph10 207 12. A pattern like \X?\d or \P{L}?\d in non-UTF-8 mode could cause a backtrack
274     past the start of the subject in the presence of bytes with the top bit
275     set, for example "\x8aBCD".
276 ph10 211
277 ph10 210 13. Added Perl 5.10 experimental backtracking controls (*FAIL), (*F), (*PRUNE),
278     (*SKIP), (*THEN), (*COMMIT), and (*ACCEPT).
279 ph10 200
280 ph10 211 14. Optimized (?!) to (*FAIL).
281 ph10 202
282 ph10 212 15. Updated the test for a valid UTF-8 string to conform to the later RFC 3629.
283     This restricts code points to be within the range 0 to 0x10FFFF, excluding
284     the "low surrogate" sequence 0xD800 to 0xDFFF. Previously, PCRE allowed the
285     full range 0 to 0x7FFFFFFF, as defined by RFC 2279. Internally, it still
286     does: it's just the validity check that is more restrictive.
287 ph10 220
288     16. Inserted checks for integer overflows during escape sequence (backslash)
289     processing, and also fixed erroneous offset values for syntax errors during
290     backslash processing.
291    
292 ph10 214 17. Fixed another case of looking too far back in non-UTF-8 mode (cf 12 above)
293 ph10 220 for patterns like [\PPP\x8a]{1,}\x80 with the subject "A\x80".
294    
295 ph10 215 18. An unterminated class in a pattern like (?1)\c[ with a "forward reference"
296     caused an overrun.
297 ph10 220
298     19. A pattern like (?:[\PPa*]*){8,} which had an "extended class" (one with
299     something other than just ASCII characters) inside a group that had an
300     unlimited repeat caused a loop at compile time (while checking to see
301     whether the group could match an empty string).
302    
303 ph10 217 20. Debugging a pattern containing \p or \P could cause a crash. For example,
304     [\P{Any}] did so. (Error in the code for printing property names.)
305 ph10 210
306 ph10 220 21. An orphan \E inside a character class could cause a crash.
307    
308     22. A repeated capturing bracket such as (A)? could cause a wild memory
309 ph10 218 reference during compilation.
310 ph10 220
311     23. There are several functions in pcre_compile() that scan along a compiled
312     expression for various reasons (e.g. to see if it's fixed length for look
313 ph10 218 behind). There were bugs in these functions when a repeated \p or \P was
314 ph10 220 present in the pattern. These operators have additional parameters compared
315     with \d, etc, and these were not being taken into account when moving along
316 ph10 218 the compiled data. Specifically:
317 ph10 220
318     (a) A item such as \p{Yi}{3} in a lookbehind was not treated as fixed
319     length.
320    
321     (b) An item such as \pL+ within a repeated group could cause crashes or
322 ph10 218 loops.
323 ph10 220
324 ph10 218 (c) A pattern such as \p{Yi}+(\P{Yi}+)(?1) could give an incorrect
325 ph10 220 "reference to non-existent subpattern" error.
326    
327 ph10 221 (d) A pattern like (\P{Yi}{2}\277)? could loop at compile time.
328    
329 ph10 219 24. A repeated \S or \W in UTF-8 mode could give wrong answers when multibyte
330 ph10 220 characters were involved (for example /\S{2}/8g with "A\x{a3}BC").
331 ph10 211
332 ph10 222 25. Using pcregrep in multiline, inverted mode (-Mv) caused it to loop.
333 ph10 218
334 ph10 227 26. Patterns such as [\P{Yi}A] which include \p or \P and just one other
335 ph10 223 character were causing crashes (broken optimization).
336 ph10 227
337 ph10 224 27. Patterns such as (\P{Yi}*\277)* (group with possible zero repeat containing
338 ph10 227 \p or \P) caused a compile-time loop.
339    
340 ph10 226 28. More problems have arisen in unanchored patterns when CRLF is a valid line
341     break. For example, the unstudied pattern [\r\n]A does not match the string
342     "\r\nA" because change 7.0/46 below moves the current point on by two
343     characters after failing to match at the start. However, the pattern \nA
344 ph10 227 *does* match, because it doesn't start till \n, and if [\r\n]A is studied,
345     the same is true. There doesn't seem any very clean way out of this, but
346     what I have chosen to do makes the common cases work: PCRE now takes note
347     of whether there can be an explicit match for \r or \n anywhere in the
348     pattern, and if so, 7.0/46 no longer applies. As part of this change,
349     there's a new PCRE_INFO_HASCRORLF option for finding out whether a compiled
350     pattern has explicit CR or LF references.
351 ph10 222
352 ph10 227 29. Added (*CR) etc for changing newline setting at start of pattern.
353 ph10 223
354 ph10 227
355 ph10 189 Version 7.2 19-Jun-07
356     ---------------------
357    
358 ph10 157 1. If the fr_FR locale cannot be found for test 3, try the "french" locale,
359     which is apparently normally available under Windows.
360 ph10 159
361     2. Re-jig the pcregrep tests with different newline settings in an attempt
362     to make them independent of the local environment's newline setting.
363 ph10 157
364 ph10 160 3. Add code to configure.ac to remove -g from the CFLAGS default settings.
365 ph10 165
366 ph10 161 4. Some of the "internals" tests were previously cut out when the link size
367     was not 2, because the output contained actual offsets. The recent new
368 ph10 165 "Z" feature of pcretest means that these can be cut out, making the tests
369     usable with all link sizes.
370    
371 ph10 164 5. Implemented Stan Switzer's goto replacement for longjmp() when not using
372     stack recursion. This gives a massive performance boost under BSD, but just
373 ph10 165 a small improvement under Linux. However, it saves one field in the frame
374 ph10 164 in all cases.
375 ph10 172
376 ph10 166 6. Added more features from the forthcoming Perl 5.10:
377 ph10 172
378 ph10 166 (a) (?-n) (where n is a string of digits) is a relative subroutine or
379     recursion call. It refers to the nth most recently opened parentheses.
380 ph10 172
381 ph10 166 (b) (?+n) is also a relative subroutine call; it refers to the nth next
382 ph10 172 to be opened parentheses.
383    
384     (c) Conditions that refer to capturing parentheses can be specified
385 ph10 167 relatively, for example, (?(-2)... or (?(+3)...
386 ph10 172
387 ph10 168 (d) \K resets the start of the current match so that everything before
388 ph10 172 is not part of it.
389    
390 ph10 171 (e) \k{name} is synonymous with \k<name> and \k'name' (.NET compatible).
391 ph10 172
392 ph10 171 (f) \g{name} is another synonym - part of Perl 5.10's unification of
393 ph10 172 reference syntax.
394 ph10 182
395 ph10 175 (g) (?| introduces a group in which the numbering of parentheses in each
396 ph10 182 alternative starts with the same number.
397 ph10 172
398 ph10 182 (h) \h, \H, \v, and \V match horizontal and vertical whitespace.
399    
400 ph10 172 7. Added two new calls to pcre_fullinfo(): PCRE_INFO_OKPARTIAL and
401     PCRE_INFO_JCHANGED.
402    
403     8. A pattern such as (.*(.)?)* caused pcre_exec() to fail by either not
404     terminating or by crashing. Diagnosed by Viktor Griph; it was in the code
405 ph10 170 for detecting groups that can match an empty string.
406 ph10 159
407 ph10 172 9. A pattern with a very large number of alternatives (more than several
408     hundred) was running out of internal workspace during the pre-compile
409     phase, where pcre_compile() figures out how much memory will be needed. A
410     bit of new cunning has reduced the workspace needed for groups with
411     alternatives. The 1000-alternative test pattern now uses 12 bytes of
412     workspace instead of running out of the 4096 that are available.
413 ph10 182
414 ph10 176 10. Inserted some missing (unsigned int) casts to get rid of compiler warnings.
415 ph10 172
416 ph10 179 11. Applied patch from Google to remove an optimization that didn't quite work.
417     The report of the bug said:
418 ph10 182
419 ph10 179 pcrecpp::RE("a*").FullMatch("aaa") matches, while
420     pcrecpp::RE("a*?").FullMatch("aaa") does not, and
421 ph10 182 pcrecpp::RE("a*?\\z").FullMatch("aaa") does again.
422 ph10 185
423 ph10 184 12. If \p or \P was used in non-UTF-8 mode on a character greater than 127
424 ph10 185 it matched the wrong number of bytes.
425 ph10 172
426 ph10 179
427 ph10 155 Version 7.1 24-Apr-07
428 ph10 98 ---------------------
429    
430 ph10 111 1. Applied Bob Rossi and Daniel G's patches to convert the build system to one
431 ph10 122 that is more "standard", making use of automake and other Autotools. There
432 ph10 99 is some re-arrangement of the files and adjustment of comments consequent
433     on this.
434 ph10 111
435     2. Part of the patch fixed a problem with the pcregrep tests. The test of -r
436     for recursive directory scanning broke on some systems because the files
437     are not scanned in any specific order and on different systems the order
438     was different. A call to "sort" has been inserted into RunGrepTest for the
439     approprate test as a short-term fix. In the longer term there may be an
440 ph10 100 alternative.
441 ph10 111
442 ph10 100 3. I had an email from Eric Raymond about problems translating some of PCRE's
443 ph10 111 man pages to HTML (despite the fact that I distribute HTML pages, some
444     people do their own conversions for various reasons). The problems
445     concerned the use of low-level troff macros .br and .in. I have therefore
446     removed all such uses from the man pages (some were redundant, some could
447 ph10 113 be replaced by .nf/.fi pairs). The 132html script that I use to generate
448     HTML has been updated to handle .nf/.fi and to complain if it encounters
449     .br or .in.
450 ph10 111
451 ph10 100 4. Updated comments in configure.ac that get placed in config.h.in and also
452 ph10 123 arranged for config.h to be included in the distribution, with the name
453 ph10 111 config.h.generic, for the benefit of those who have to compile without
454     Autotools (compare pcre.h, which is now distributed as pcre.h.generic).
455    
456     5. Updated the support (such as it is) for Virtual Pascal, thanks to Stefan
457     Weber: (1) pcre_internal.h was missing some function renames; (2) updated
458 ph10 127 makevp.bat for the current PCRE, using the additional files
459 ph10 135 makevp_c.txt, makevp_l.txt, and pcregexp.pas.
460 ph10 111
461     6. A Windows user reported a minor discrepancy with test 2, which turned out
462     to be caused by a trailing space on an input line that had got lost in his
463 ph10 102 copy. The trailing space was an accident, so I've just removed it.
464 ph10 111
465 ph10 104 7. Add -Wl,-R... flags in pcre-config.in for *BSD* systems, as I'm told
466 ph10 111 that is needed.
467    
468 ph10 105 8. Mark ucp_table (in ucptable.h) and ucp_gentype (in pcre_ucp_searchfuncs.c)
469     as "const" (a) because they are and (b) because it helps the PHP
470     maintainers who have recently made a script to detect big data structures
471 ph10 111 in the php code that should be moved to the .rodata section. I remembered
472     to update Builducptable as well, so it won't revert if ucptable.h is ever
473 ph10 105 re-created.
474 ph10 111
475     9. Added some extra #ifdef SUPPORT_UTF8 conditionals into pcretest.c,
476 ph10 107 pcre_printint.src, pcre_compile.c, pcre_study.c, and pcre_tables.c, in
477 ph10 111 order to be able to cut out the UTF-8 tables in the latter when UTF-8
478     support is not required. This saves 1.5-2K of code, which is important in
479 ph10 107 some applications.
480 ph10 111
481 ph10 110 Later: more #ifdefs are needed in pcre_ord2utf8.c and pcre_valid_utf8.c
482 ph10 111 so as not to refer to the tables, even though these functions will never be
483     called when UTF-8 support is disabled. Otherwise there are problems with a
484     shared library.
485    
486 ph10 118 10. Fixed two bugs in the emulated memmove() function in pcre_internal.h:
487    
488     (a) It was defining its arguments as char * instead of void *.
489    
490 ph10 123 (b) It was assuming that all moves were upwards in memory; this was true
491     a long time ago when I wrote it, but is no longer the case.
492    
493 ph10 118 The emulated memove() is provided for those environments that have neither
494 ph10 123 memmove() nor bcopy(). I didn't think anyone used it these days, but that
495 ph10 118 is clearly not the case, as these two bugs were recently reported.
496 ph10 123
497 ph10 111 11. The script PrepareRelease is now distributed: it calls 132html, CleanTxt,
498 ph10 123 and Detrail to create the HTML documentation, the .txt form of the man
499     pages, and it removes trailing spaces from listed files. It also creates
500     pcre.h.generic and config.h.generic from pcre.h and config.h. In the latter
501     case, it wraps all the #defines with #ifndefs. This script should be run
502 ph10 111 before "make dist".
503 ph10 123
504 ph10 115 12. Fixed two fairly obscure bugs concerned with quantified caseless matching
505     with Unicode property support.
506 ph10 123
507     (a) For a maximizing quantifier, if the two different cases of the
508     character were of different lengths in their UTF-8 codings (there are
509     some cases like this - I found 11), and the matching function had to
510 ph10 115 back up over a mixture of the two cases, it incorrectly assumed they
511     were both the same length.
512 ph10 123
513     (b) When PCRE was configured to use the heap rather than the stack for
514     recursion during matching, it was not correctly preserving the data for
515     the other case of a UTF-8 character when checking ahead for a match
516     while processing a minimizing repeat. If the check also involved
517 ph10 115 matching a wide character, but failed, corruption could cause an
518     erroneous result when trying to check for a repeat of the original
519     character.
520 ph10 123
521 ph10 116 13. Some tidying changes to the testing mechanism:
522 ph10 98
523 ph10 116 (a) The RunTest script now detects the internal link size and whether there
524     is UTF-8 and UCP support by running ./pcretest -C instead of relying on
525 ph10 123 values substituted by "configure". (The RunGrepTest script already did
526     this for UTF-8.) The configure.ac script no longer substitutes the
527     relevant variables.
528    
529 ph10 116 (b) The debugging options /B and /D in pcretest show the compiled bytecode
530     with length and offset values. This means that the output is different
531     for different internal link sizes. Test 2 is skipped for link sizes
532     other than 2 because of this, bypassing the problem. Unfortunately,
533     there was also a test in test 3 (the locale tests) that used /B and
534 ph10 123 failed for link sizes other than 2. Rather than cut the whole test out,
535     I have added a new /Z option to pcretest that replaces the length and
536     offset values with spaces. This is now used to make test 3 independent
537 ph10 122 of link size. (Test 2 will be tidied up later.)
538 ph10 123
539     14. If erroroffset was passed as NULL to pcre_compile, it provoked a
540 ph10 122 segmentation fault instead of returning the appropriate error message.
541 ph10 134
542 ph10 131 15. In multiline mode when the newline sequence was set to "any", the pattern
543 ph10 134 ^$ would give a match between the \r and \n of a subject such as "A\r\nB".
544     This doesn't seem right; it now treats the CRLF combination as the line
545     ending, and so does not match in that case. It's only a pattern such as ^$
546     that would hit this one: something like ^ABC$ would have failed after \r
547     and then tried again after \r\n.
548    
549 ph10 131 16. Changed the comparison command for RunGrepTest from "diff -u" to "diff -ub"
550 ph10 134 in an attempt to make files that differ only in their line terminators
551     compare equal. This works on Linux.
552 ph10 142
553 ph10 141 17. Under certain error circumstances pcregrep might try to free random memory
554     as it exited. This is now fixed, thanks to valgrind.
555 ph10 142
556 ph10 141 19. In pcretest, if the pattern /(?m)^$/g<any> was matched against the string
557 ph10 142 "abc\r\n\r\n", it found an unwanted second match after the second \r. This
558     was because its rules for how to advance for /g after matching an empty
559 ph10 143 string at the end of a line did not allow for this case. They now check for
560     it specially.
561 ph10 150
562     20. pcretest is supposed to handle patterns and data of any length, by
563     extending its buffers when necessary. It was getting this wrong when the
564 ph10 147 buffer for a data line had to be extended.
565 ph10 150
566 ph10 149 21. Added PCRE_NEWLINE_ANYCRLF which is like ANY, but matches only CR, LF, or
567 ph10 150 CRLF as a newline sequence.
568 ph10 152
569 ph10 151 22. Code for handling Unicode properties in pcre_dfa_exec() wasn't being cut
570 ph10 152 out by #ifdef SUPPORT_UCP. This did no harm, as it could never be used, but
571     I have nevertheless tidied it up.
572 ph10 111
573 ph10 152 23. Added some casts to kill warnings from HP-UX ia64 compiler.
574 ph10 123
575 ph10 153 24. Added a man page for pcre-config.
576 ph10 152
577 ph10 153
578 nigel 93 Version 7.0 19-Dec-06
579     ---------------------
580    
581     1. Fixed a signed/unsigned compiler warning in pcre_compile.c, shown up by
582     moving to gcc 4.1.1.
583    
584     2. The -S option for pcretest uses setrlimit(); I had omitted to #include
585     sys/time.h, which is documented as needed for this function. It doesn't
586     seem to matter on Linux, but it showed up on some releases of OS X.
587    
588     3. It seems that there are systems where bytes whose values are greater than
589     127 match isprint() in the "C" locale. The "C" locale should be the
590     default when a C program starts up. In most systems, only ASCII printing
591     characters match isprint(). This difference caused the output from pcretest
592     to vary, making some of the tests fail. I have changed pcretest so that:
593    
594     (a) When it is outputting text in the compiled version of a pattern, bytes
595     other than 32-126 are always shown as hex escapes.
596    
597     (b) When it is outputting text that is a matched part of a subject string,
598     it does the same, unless a different locale has been set for the match
599     (using the /L modifier). In this case, it uses isprint() to decide.
600    
601     4. Fixed a major bug that caused incorrect computation of the amount of memory
602     required for a compiled pattern when options that changed within the
603     pattern affected the logic of the preliminary scan that determines the
604     length. The relevant options are -x, and -i in UTF-8 mode. The result was
605     that the computed length was too small. The symptoms of this bug were
606     either the PCRE error "internal error: code overflow" from pcre_compile(),
607     or a glibc crash with a message such as "pcretest: free(): invalid next
608     size (fast)". Examples of patterns that provoked this bug (shown in
609     pcretest format) are:
610    
611     /(?-x: )/x
612     /(?x)(?-x: \s*#\s*)/
613     /((?i)[\x{c0}])/8
614     /(?i:[\x{c0}])/8
615    
616     HOWEVER: Change 17 below makes this fix obsolete as the memory computation
617     is now done differently.
618    
619     5. Applied patches from Google to: (a) add a QuoteMeta function to the C++
620     wrapper classes; (b) implement a new function in the C++ scanner that is
621     more efficient than the old way of doing things because it avoids levels of
622     recursion in the regex matching; (c) add a paragraph to the documentation
623     for the FullMatch() function.
624    
625     6. The escape sequence \n was being treated as whatever was defined as
626     "newline". Not only was this contrary to the documentation, which states
627     that \n is character 10 (hex 0A), but it also went horribly wrong when
628     "newline" was defined as CRLF. This has been fixed.
629    
630     7. In pcre_dfa_exec.c the value of an unsigned integer (the variable called c)
631     was being set to -1 for the "end of line" case (supposedly a value that no
632     character can have). Though this value is never used (the check for end of
633     line is "zero bytes in current character"), it caused compiler complaints.
634     I've changed it to 0xffffffff.
635    
636     8. In pcre_version.c, the version string was being built by a sequence of
637     C macros that, in the event of PCRE_PRERELEASE being defined as an empty
638     string (as it is for production releases) called a macro with an empty
639     argument. The C standard says the result of this is undefined. The gcc
640     compiler treats it as an empty string (which was what was wanted) but it is
641     reported that Visual C gives an error. The source has been hacked around to
642     avoid this problem.
643    
644     9. On the advice of a Windows user, included <io.h> and <fcntl.h> in Windows
645     builds of pcretest, and changed the call to _setmode() to use _O_BINARY
646     instead of 0x8000. Made all the #ifdefs test both _WIN32 and WIN32 (not all
647     of them did).
648    
649     10. Originally, pcretest opened its input and output without "b"; then I was
650     told that "b" was needed in some environments, so it was added for release
651     5.0 to both the input and output. (It makes no difference on Unix-like
652     systems.) Later I was told that it is wrong for the input on Windows. I've
653     now abstracted the modes into two macros, to make it easier to fiddle with
654     them, and removed "b" from the input mode under Windows.
655    
656     11. Added pkgconfig support for the C++ wrapper library, libpcrecpp.
657    
658     12. Added -help and --help to pcretest as an official way of being reminded
659     of the options.
660    
661     13. Removed some redundant semicolons after macro calls in pcrecpparg.h.in
662     and pcrecpp.cc because they annoy compilers at high warning levels.
663    
664     14. A bit of tidying/refactoring in pcre_exec.c in the main bumpalong loop.
665    
666     15. Fixed an occurrence of == in configure.ac that should have been = (shell
667     scripts are not C programs :-) and which was not noticed because it works
668     on Linux.
669    
670     16. pcretest is supposed to handle any length of pattern and data line (as one
671     line or as a continued sequence of lines) by extending its input buffer if
672     necessary. This feature was broken for very long pattern lines, leading to
673     a string of junk being passed to pcre_compile() if the pattern was longer
674     than about 50K.
675    
676     17. I have done a major re-factoring of the way pcre_compile() computes the
677     amount of memory needed for a compiled pattern. Previously, there was code
678     that made a preliminary scan of the pattern in order to do this. That was
679     OK when PCRE was new, but as the facilities have expanded, it has become
680     harder and harder to keep it in step with the real compile phase, and there
681     have been a number of bugs (see for example, 4 above). I have now found a
682     cunning way of running the real compile function in a "fake" mode that
683     enables it to compute how much memory it would need, while actually only
684     ever using a few hundred bytes of working memory and without too many
685     tests of the mode. This should make future maintenance and development
686     easier. A side effect of this work is that the limit of 200 on the nesting
687     depth of parentheses has been removed (though this was never a serious
688     limitation, I suspect). However, there is a downside: pcre_compile() now
689     runs more slowly than before (30% or more, depending on the pattern). I
690     hope this isn't a big issue. There is no effect on runtime performance.
691    
692     18. Fixed a minor bug in pcretest: if a pattern line was not terminated by a
693     newline (only possible for the last line of a file) and it was a
694     pattern that set a locale (followed by /Lsomething), pcretest crashed.
695    
696     19. Added additional timing features to pcretest. (1) The -tm option now times
697     matching only, not compiling. (2) Both -t and -tm can be followed, as a
698     separate command line item, by a number that specifies the number of
699     repeats to use when timing. The default is 50000; this gives better
700     precision, but takes uncomfortably long for very large patterns.
701    
702     20. Extended pcre_study() to be more clever in cases where a branch of a
703     subpattern has no definite first character. For example, (a*|b*)[cd] would
704     previously give no result from pcre_study(). Now it recognizes that the
705     first character must be a, b, c, or d.
706    
707     21. There was an incorrect error "recursive call could loop indefinitely" if
708     a subpattern (or the entire pattern) that was being tested for matching an
709     empty string contained only one non-empty item after a nested subpattern.
710     For example, the pattern (?>\x{100}*)\d(?R) provoked this error
711     incorrectly, because the \d was being skipped in the check.
712    
713     22. The pcretest program now has a new pattern option /B and a command line
714     option -b, which is equivalent to adding /B to every pattern. This causes
715     it to show the compiled bytecode, without the additional information that
716     -d shows. The effect of -d is now the same as -b with -i (and similarly, /D
717     is the same as /B/I).
718    
719     23. A new optimization is now able automatically to treat some sequences such
720     as a*b as a*+b. More specifically, if something simple (such as a character
721     or a simple class like \d) has an unlimited quantifier, and is followed by
722     something that cannot possibly match the quantified thing, the quantifier
723     is automatically "possessified".
724    
725     24. A recursive reference to a subpattern whose number was greater than 39
726     went wrong under certain circumstances in UTF-8 mode. This bug could also
727     have affected the operation of pcre_study().
728    
729     25. Realized that a little bit of performance could be had by replacing
730     (c & 0xc0) == 0xc0 with c >= 0xc0 when processing UTF-8 characters.
731    
732     26. Timing data from pcretest is now shown to 4 decimal places instead of 3.
733    
734     27. Possessive quantifiers such as a++ were previously implemented by turning
735     them into atomic groups such as ($>a+). Now they have their own opcodes,
736     which improves performance. This includes the automatically created ones
737     from 23 above.
738    
739     28. A pattern such as (?=(\w+))\1: which simulates an atomic group using a
740     lookahead was broken if it was not anchored. PCRE was mistakenly expecting
741     the first matched character to be a colon. This applied both to named and
742     numbered groups.
743    
744     29. The ucpinternal.h header file was missing its idempotency #ifdef.
745    
746     30. I was sent a "project" file called libpcre.a.dev which I understand makes
747     building PCRE on Windows easier, so I have included it in the distribution.
748    
749     31. There is now a check in pcretest against a ridiculously large number being
750     returned by pcre_exec() or pcre_dfa_exec(). If this happens in a /g or /G
751     loop, the loop is abandoned.
752    
753     32. Forward references to subpatterns in conditions such as (?(2)...) where
754     subpattern 2 is defined later cause pcre_compile() to search forwards in
755     the pattern for the relevant set of parentheses. This search went wrong
756     when there were unescaped parentheses in a character class, parentheses
757     escaped with \Q...\E, or parentheses in a #-comment in /x mode.
758    
759     33. "Subroutine" calls and backreferences were previously restricted to
760     referencing subpatterns earlier in the regex. This restriction has now
761     been removed.
762    
763     34. Added a number of extra features that are going to be in Perl 5.10. On the
764     whole, these are just syntactic alternatives for features that PCRE had
765     previously implemented using the Python syntax or my own invention. The
766     other formats are all retained for compatibility.
767    
768     (a) Named groups can now be defined as (?<name>...) or (?'name'...) as well
769     as (?P<name>...). The new forms, as well as being in Perl 5.10, are
770     also .NET compatible.
771    
772     (b) A recursion or subroutine call to a named group can now be defined as
773     (?&name) as well as (?P>name).
774    
775     (c) A backreference to a named group can now be defined as \k<name> or
776     \k'name' as well as (?P=name). The new forms, as well as being in Perl
777     5.10, are also .NET compatible.
778    
779     (d) A conditional reference to a named group can now use the syntax
780     (?(<name>) or (?('name') as well as (?(name).
781    
782     (e) A "conditional group" of the form (?(DEFINE)...) can be used to define
783     groups (named and numbered) that are never evaluated inline, but can be
784     called as "subroutines" from elsewhere. In effect, the DEFINE condition
785     is always false. There may be only one alternative in such a group.
786    
787     (f) A test for recursion can be given as (?(R1).. or (?(R&name)... as well
788     as the simple (?(R). The condition is true only if the most recent
789     recursion is that of the given number or name. It does not search out
790     through the entire recursion stack.
791    
792     (g) The escape \gN or \g{N} has been added, where N is a positive or
793     negative number, specifying an absolute or relative reference.
794    
795     35. Tidied to get rid of some further signed/unsigned compiler warnings and
796     some "unreachable code" warnings.
797    
798     36. Updated the Unicode property tables to Unicode version 5.0.0. Amongst other
799     things, this adds five new scripts.
800    
801     37. Perl ignores orphaned \E escapes completely. PCRE now does the same.
802     There were also incompatibilities regarding the handling of \Q..\E inside
803     character classes, for example with patterns like [\Qa\E-\Qz\E] where the
804     hyphen was adjacent to \Q or \E. I hope I've cleared all this up now.
805    
806     38. Like Perl, PCRE detects when an indefinitely repeated parenthesized group
807     matches an empty string, and forcibly breaks the loop. There were bugs in
808     this code in non-simple cases. For a pattern such as ^(a()*)* matched
809     against aaaa the result was just "a" rather than "aaaa", for example. Two
810     separate and independent bugs (that affected different cases) have been
811     fixed.
812    
813     39. Refactored the code to abolish the use of different opcodes for small
814     capturing bracket numbers. This is a tidy that I avoided doing when I
815     removed the limit on the number of capturing brackets for 3.5 back in 2001.
816     The new approach is not only tidier, it makes it possible to reduce the
817     memory needed to fix the previous bug (38).
818    
819     40. Implemented PCRE_NEWLINE_ANY to recognize any of the Unicode newline
820     sequences (http://unicode.org/unicode/reports/tr18/) as "newline" when
821     processing dot, circumflex, or dollar metacharacters, or #-comments in /x
822     mode.
823    
824     41. Add \R to match any Unicode newline sequence, as suggested in the Unicode
825     report.
826    
827     42. Applied patch, originally from Ari Pollak, modified by Google, to allow
828     copy construction and assignment in the C++ wrapper.
829    
830     43. Updated pcregrep to support "--newline=any". In the process, I fixed a
831     couple of bugs that could have given wrong results in the "--newline=crlf"
832     case.
833    
834     44. Added a number of casts and did some reorganization of signed/unsigned int
835     variables following suggestions from Dair Grant. Also renamed the variable
836     "this" as "item" because it is a C++ keyword.
837    
838     45. Arranged for dftables to add
839    
840     #include "pcre_internal.h"
841    
842     to pcre_chartables.c because without it, gcc 4.x may remove the array
843     definition from the final binary if PCRE is built into a static library and
844     dead code stripping is activated.
845    
846     46. For an unanchored pattern, if a match attempt fails at the start of a
847     newline sequence, and the newline setting is CRLF or ANY, and the next two
848     characters are CRLF, advance by two characters instead of one.
849    
850    
851 nigel 91 Version 6.7 04-Jul-06
852     ---------------------
853    
854     1. In order to handle tests when input lines are enormously long, pcretest has
855     been re-factored so that it automatically extends its buffers when
856     necessary. The code is crude, but this _is_ just a test program. The
857     default size has been increased from 32K to 50K.
858    
859     2. The code in pcre_study() was using the value of the re argument before
860     testing it for NULL. (Of course, in any sensible call of the function, it
861     won't be NULL.)
862    
863     3. The memmove() emulation function in pcre_internal.h, which is used on
864     systems that lack both memmove() and bcopy() - that is, hardly ever -
865     was missing a "static" storage class specifier.
866    
867     4. When UTF-8 mode was not set, PCRE looped when compiling certain patterns
868     containing an extended class (one that cannot be represented by a bitmap
869     because it contains high-valued characters or Unicode property items, e.g.
870     [\pZ]). Almost always one would set UTF-8 mode when processing such a
871     pattern, but PCRE should not loop if you do not (it no longer does).
872     [Detail: two cases were found: (a) a repeated subpattern containing an
873     extended class; (b) a recursive reference to a subpattern that followed a
874     previous extended class. It wasn't skipping over the extended class
875     correctly when UTF-8 mode was not set.]
876    
877     5. A negated single-character class was not being recognized as fixed-length
878     in lookbehind assertions such as (?<=[^f]), leading to an incorrect
879     compile error "lookbehind assertion is not fixed length".
880    
881     6. The RunPerlTest auxiliary script was showing an unexpected difference
882     between PCRE and Perl for UTF-8 tests. It turns out that it is hard to
883     write a Perl script that can interpret lines of an input file either as
884     byte characters or as UTF-8, which is what "perltest" was being required to
885     do for the non-UTF-8 and UTF-8 tests, respectively. Essentially what you
886     can't do is switch easily at run time between having the "use utf8;" pragma
887     or not. In the end, I fudged it by using the RunPerlTest script to insert
888     "use utf8;" explicitly for the UTF-8 tests.
889    
890     7. In multiline (/m) mode, PCRE was matching ^ after a terminating newline at
891     the end of the subject string, contrary to the documentation and to what
892     Perl does. This was true of both matching functions. Now it matches only at
893     the start of the subject and immediately after *internal* newlines.
894    
895     8. A call of pcre_fullinfo() from pcretest to get the option bits was passing
896     a pointer to an int instead of a pointer to an unsigned long int. This
897     caused problems on 64-bit systems.
898    
899     9. Applied a patch from the folks at Google to pcrecpp.cc, to fix "another
900     instance of the 'standard' template library not being so standard".
901    
902     10. There was no check on the number of named subpatterns nor the maximum
903     length of a subpattern name. The product of these values is used to compute
904     the size of the memory block for a compiled pattern. By supplying a very
905     long subpattern name and a large number of named subpatterns, the size
906     computation could be caused to overflow. This is now prevented by limiting
907     the length of names to 32 characters, and the number of named subpatterns
908     to 10,000.
909    
910     11. Subpatterns that are repeated with specific counts have to be replicated in
911     the compiled pattern. The size of memory for this was computed from the
912     length of the subpattern and the repeat count. The latter is limited to
913     65535, but there was no limit on the former, meaning that integer overflow
914     could in principle occur. The compiled length of a repeated subpattern is
915     now limited to 30,000 bytes in order to prevent this.
916    
917     12. Added the optional facility to have named substrings with the same name.
918    
919     13. Added the ability to use a named substring as a condition, using the
920     Python syntax: (?(name)yes|no). This overloads (?(R)... and names that
921     are numbers (not recommended). Forward references are permitted.
922    
923     14. Added forward references in named backreferences (if you see what I mean).
924    
925     15. In UTF-8 mode, with the PCRE_DOTALL option set, a quantified dot in the
926     pattern could run off the end of the subject. For example, the pattern
927     "(?s)(.{1,5})"8 did this with the subject "ab".
928    
929     16. If PCRE_DOTALL or PCRE_MULTILINE were set, pcre_dfa_exec() behaved as if
930     PCRE_CASELESS was set when matching characters that were quantified with ?
931     or *.
932    
933     17. A character class other than a single negated character that had a minimum
934     but no maximum quantifier - for example [ab]{6,} - was not handled
935     correctly by pce_dfa_exec(). It would match only one character.
936    
937     18. A valid (though odd) pattern that looked like a POSIX character
938     class but used an invalid character after [ (for example [[,abc,]]) caused
939     pcre_compile() to give the error "Failed: internal error: code overflow" or
940     in some cases to crash with a glibc free() error. This could even happen if
941     the pattern terminated after [[ but there just happened to be a sequence of
942     letters, a binary zero, and a closing ] in the memory that followed.
943    
944     19. Perl's treatment of octal escapes in the range \400 to \777 has changed
945     over the years. Originally (before any Unicode support), just the bottom 8
946     bits were taken. Thus, for example, \500 really meant \100. Nowadays the
947     output from "man perlunicode" includes this:
948    
949     The regular expression compiler produces polymorphic opcodes. That
950     is, the pattern adapts to the data and automatically switches to
951     the Unicode character scheme when presented with Unicode data--or
952     instead uses a traditional byte scheme when presented with byte
953     data.
954    
955     Sadly, a wide octal escape does not cause a switch, and in a string with
956     no other multibyte characters, these octal escapes are treated as before.
957     Thus, in Perl, the pattern /\500/ actually matches \100 but the pattern
958     /\500|\x{1ff}/ matches \500 or \777 because the whole thing is treated as a
959     Unicode string.
960    
961     I have not perpetrated such confusion in PCRE. Up till now, it took just
962     the bottom 8 bits, as in old Perl. I have now made octal escapes with
963     values greater than \377 illegal in non-UTF-8 mode. In UTF-8 mode they
964     translate to the appropriate multibyte character.
965    
966     29. Applied some refactoring to reduce the number of warnings from Microsoft
967     and Borland compilers. This has included removing the fudge introduced
968     seven years ago for the OS/2 compiler (see 2.02/2 below) because it caused
969     a warning about an unused variable.
970    
971     21. PCRE has not included VT (character 0x0b) in the set of whitespace
972     characters since release 4.0, because Perl (from release 5.004) does not.
973     [Or at least, is documented not to: some releases seem to be in conflict
974     with the documentation.] However, when a pattern was studied with
975     pcre_study() and all its branches started with \s, PCRE still included VT
976     as a possible starting character. Of course, this did no harm; it just
977     caused an unnecessary match attempt.
978    
979     22. Removed a now-redundant internal flag bit that recorded the fact that case
980     dependency changed within the pattern. This was once needed for "required
981     byte" processing, but is no longer used. This recovers a now-scarce options
982     bit. Also moved the least significant internal flag bit to the most-
983     significant bit of the word, which was not previously used (hangover from
984     the days when it was an int rather than a uint) to free up another bit for
985     the future.
986    
987     23. Added support for CRLF line endings as well as CR and LF. As well as the
988     default being selectable at build time, it can now be changed at runtime
989     via the PCRE_NEWLINE_xxx flags. There are now options for pcregrep to
990     specify that it is scanning data with non-default line endings.
991    
992     24. Changed the definition of CXXLINK to make it agree with the definition of
993     LINK in the Makefile, by replacing LDFLAGS to CXXFLAGS.
994    
995     25. Applied Ian Taylor's patches to avoid using another stack frame for tail
996     recursions. This makes a big different to stack usage for some patterns.
997    
998     26. If a subpattern containing a named recursion or subroutine reference such
999     as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
1000     the space required for the compiled pattern went wrong and gave too small a
1001     value. Depending on the environment, this could lead to "Failed: internal
1002     error: code overflow at offset 49" or "glibc detected double free or
1003     corruption" errors.
1004    
1005     27. Applied patches from Google (a) to support the new newline modes and (b) to
1006     advance over multibyte UTF-8 characters in GlobalReplace.
1007    
1008     28. Change free() to pcre_free() in pcredemo.c. Apparently this makes a
1009     difference for some implementation of PCRE in some Windows version.
1010    
1011     29. Added some extra testing facilities to pcretest:
1012    
1013     \q<number> in a data line sets the "match limit" value
1014     \Q<number> in a data line sets the "match recursion limt" value
1015     -S <number> sets the stack size, where <number> is in megabytes
1016    
1017     The -S option isn't available for Windows.
1018    
1019    
1020 nigel 89 Version 6.6 06-Feb-06
1021     ---------------------
1022    
1023     1. Change 16(a) for 6.5 broke things, because PCRE_DATA_SCOPE was not defined
1024     in pcreposix.h. I have copied the definition from pcre.h.
1025    
1026     2. Change 25 for 6.5 broke compilation in a build directory out-of-tree
1027     because pcre.h is no longer a built file.
1028    
1029     3. Added Jeff Friedl's additional debugging patches to pcregrep. These are
1030     not normally included in the compiled code.
1031    
1032    
1033 nigel 87 Version 6.5 01-Feb-06
1034     ---------------------
1035    
1036     1. When using the partial match feature with pcre_dfa_exec(), it was not
1037     anchoring the second and subsequent partial matches at the new starting
1038     point. This could lead to incorrect results. For example, with the pattern
1039     /1234/, partially matching against "123" and then "a4" gave a match.
1040    
1041     2. Changes to pcregrep:
1042    
1043     (a) All non-match returns from pcre_exec() were being treated as failures
1044     to match the line. Now, unless the error is PCRE_ERROR_NOMATCH, an
1045     error message is output. Some extra information is given for the
1046     PCRE_ERROR_MATCHLIMIT and PCRE_ERROR_RECURSIONLIMIT errors, which are
1047     probably the only errors that are likely to be caused by users (by
1048     specifying a regex that has nested indefinite repeats, for instance).
1049     If there are more than 20 of these errors, pcregrep is abandoned.
1050    
1051     (b) A binary zero was treated as data while matching, but terminated the
1052     output line if it was written out. This has been fixed: binary zeroes
1053     are now no different to any other data bytes.
1054    
1055     (c) Whichever of the LC_ALL or LC_CTYPE environment variables is set is
1056     used to set a locale for matching. The --locale=xxxx long option has
1057     been added (no short equivalent) to specify a locale explicitly on the
1058     pcregrep command, overriding the environment variables.
1059    
1060     (d) When -B was used with -n, some line numbers in the output were one less
1061     than they should have been.
1062    
1063     (e) Added the -o (--only-matching) option.
1064    
1065     (f) If -A or -C was used with -c (count only), some lines of context were
1066     accidentally printed for the final match.
1067    
1068     (g) Added the -H (--with-filename) option.
1069    
1070     (h) The combination of options -rh failed to suppress file names for files
1071     that were found from directory arguments.
1072    
1073     (i) Added the -D (--devices) and -d (--directories) options.
1074    
1075     (j) Added the -F (--fixed-strings) option.
1076    
1077     (k) Allow "-" to be used as a file name for -f as well as for a data file.
1078    
1079     (l) Added the --colo(u)r option.
1080    
1081     (m) Added Jeffrey Friedl's -S testing option, but within #ifdefs so that it
1082     is not present by default.
1083    
1084     3. A nasty bug was discovered in the handling of recursive patterns, that is,
1085     items such as (?R) or (?1), when the recursion could match a number of
1086     alternatives. If it matched one of the alternatives, but subsequently,
1087     outside the recursion, there was a failure, the code tried to back up into
1088     the recursion. However, because of the way PCRE is implemented, this is not
1089     possible, and the result was an incorrect result from the match.
1090    
1091     In order to prevent this happening, the specification of recursion has
1092     been changed so that all such subpatterns are automatically treated as
1093     atomic groups. Thus, for example, (?R) is treated as if it were (?>(?R)).
1094    
1095     4. I had overlooked the fact that, in some locales, there are characters for
1096     which isalpha() is true but neither isupper() nor islower() are true. In
1097     the fr_FR locale, for instance, the \xAA and \xBA characters (ordmasculine
1098     and ordfeminine) are like this. This affected the treatment of \w and \W
1099     when they appeared in character classes, but not when they appeared outside
1100     a character class. The bit map for "word" characters is now created
1101     separately from the results of isalnum() instead of just taking it from the
1102     upper, lower, and digit maps. (Plus the underscore character, of course.)
1103    
1104     5. The above bug also affected the handling of POSIX character classes such as
1105     [[:alpha:]] and [[:alnum:]]. These do not have their own bit maps in PCRE's
1106     permanent tables. Instead, the bit maps for such a class were previously
1107     created as the appropriate unions of the upper, lower, and digit bitmaps.
1108     Now they are created by subtraction from the [[:word:]] class, which has
1109     its own bitmap.
1110    
1111     6. The [[:blank:]] character class matches horizontal, but not vertical space.
1112     It is created by subtracting the vertical space characters (\x09, \x0a,
1113     \x0b, \x0c) from the [[:space:]] bitmap. Previously, however, the
1114     subtraction was done in the overall bitmap for a character class, meaning
1115     that a class such as [\x0c[:blank:]] was incorrect because \x0c would not
1116     be recognized. This bug has been fixed.
1117    
1118     7. Patches from the folks at Google:
1119    
1120     (a) pcrecpp.cc: "to handle a corner case that may or may not happen in
1121     real life, but is still worth protecting against".
1122    
1123     (b) pcrecpp.cc: "corrects a bug when negative radixes are used with
1124     regular expressions".
1125    
1126     (c) pcre_scanner.cc: avoid use of std::count() because not all systems
1127     have it.
1128    
1129     (d) Split off pcrecpparg.h from pcrecpp.h and had the former built by
1130     "configure" and the latter not, in order to fix a problem somebody had
1131     with compiling the Arg class on HP-UX.
1132    
1133     (e) Improve the error-handling of the C++ wrapper a little bit.
1134    
1135     (f) New tests for checking recursion limiting.
1136    
1137     8. The pcre_memmove() function, which is used only if the environment does not
1138     have a standard memmove() function (and is therefore rarely compiled),
1139     contained two bugs: (a) use of int instead of size_t, and (b) it was not
1140     returning a result (though PCRE never actually uses the result).
1141    
1142     9. In the POSIX regexec() interface, if nmatch is specified as a ridiculously
1143     large number - greater than INT_MAX/(3*sizeof(int)) - REG_ESPACE is
1144     returned instead of calling malloc() with an overflowing number that would
1145     most likely cause subsequent chaos.
1146    
1147     10. The debugging option of pcretest was not showing the NO_AUTO_CAPTURE flag.
1148    
1149     11. The POSIX flag REG_NOSUB is now supported. When a pattern that was compiled
1150     with this option is matched, the nmatch and pmatch options of regexec() are
1151     ignored.
1152    
1153     12. Added REG_UTF8 to the POSIX interface. This is not defined by POSIX, but is
1154     provided in case anyone wants to the the POSIX interface with UTF-8
1155     strings.
1156    
1157     13. Added CXXLDFLAGS to the Makefile parameters to provide settings only on the
1158     C++ linking (needed for some HP-UX environments).
1159    
1160     14. Avoid compiler warnings in get_ucpname() when compiled without UCP support
1161     (unused parameter) and in the pcre_printint() function (omitted "default"
1162     switch label when the default is to do nothing).
1163    
1164     15. Added some code to make it possible, when PCRE is compiled as a C++
1165     library, to replace subject pointers for pcre_exec() with a smart pointer
1166     class, thus making it possible to process discontinuous strings.
1167    
1168     16. The two macros PCRE_EXPORT and PCRE_DATA_SCOPE are confusing, and perform
1169     much the same function. They were added by different people who were trying
1170     to make PCRE easy to compile on non-Unix systems. It has been suggested
1171     that PCRE_EXPORT be abolished now that there is more automatic apparatus
1172     for compiling on Windows systems. I have therefore replaced it with
1173     PCRE_DATA_SCOPE. This is set automatically for Windows; if not set it
1174     defaults to "extern" for C or "extern C" for C++, which works fine on
1175     Unix-like systems. It is now possible to override the value of PCRE_DATA_
1176     SCOPE with something explicit in config.h. In addition:
1177    
1178     (a) pcreposix.h still had just "extern" instead of either of these macros;
1179     I have replaced it with PCRE_DATA_SCOPE.
1180    
1181     (b) Functions such as _pcre_xclass(), which are internal to the library,
1182     but external in the C sense, all had PCRE_EXPORT in their definitions.
1183     This is apparently wrong for the Windows case, so I have removed it.
1184     (It makes no difference on Unix-like systems.)
1185    
1186     17. Added a new limit, MATCH_LIMIT_RECURSION, which limits the depth of nesting
1187     of recursive calls to match(). This is different to MATCH_LIMIT because
1188     that limits the total number of calls to match(), not all of which increase
1189     the depth of recursion. Limiting the recursion depth limits the amount of
1190     stack (or heap if NO_RECURSE is set) that is used. The default can be set
1191     when PCRE is compiled, and changed at run time. A patch from Google adds
1192     this functionality to the C++ interface.
1193    
1194     18. Changes to the handling of Unicode character properties:
1195    
1196     (a) Updated the table to Unicode 4.1.0.
1197    
1198     (b) Recognize characters that are not in the table as "Cn" (undefined).
1199    
1200     (c) I revised the way the table is implemented to a much improved format
1201     which includes recognition of ranges. It now supports the ranges that
1202     are defined in UnicodeData.txt, and it also amalgamates other
1203     characters into ranges. This has reduced the number of entries in the
1204     table from around 16,000 to around 3,000, thus reducing its size
1205     considerably. I realized I did not need to use a tree structure after
1206     all - a binary chop search is just as efficient. Having reduced the
1207     number of entries, I extended their size from 6 bytes to 8 bytes to
1208     allow for more data.
1209    
1210     (d) Added support for Unicode script names via properties such as \p{Han}.
1211    
1212     19. In UTF-8 mode, a backslash followed by a non-Ascii character was not
1213     matching that character.
1214    
1215     20. When matching a repeated Unicode property with a minimum greater than zero,
1216     (for example \pL{2,}), PCRE could look past the end of the subject if it
1217     reached it while seeking the minimum number of characters. This could
1218     happen only if some of the characters were more than one byte long, because
1219     there is a check for at least the minimum number of bytes.
1220    
1221     21. Refactored the implementation of \p and \P so as to be more general, to
1222     allow for more different types of property in future. This has changed the
1223     compiled form incompatibly. Anybody with saved compiled patterns that use
1224     \p or \P will have to recompile them.
1225    
1226     22. Added "Any" and "L&" to the supported property types.
1227    
1228     23. Recognize \x{...} as a code point specifier, even when not in UTF-8 mode,
1229     but give a compile time error if the value is greater than 0xff.
1230    
1231     24. The man pages for pcrepartial, pcreprecompile, and pcre_compile2 were
1232     accidentally not being installed or uninstalled.
1233    
1234     25. The pcre.h file was built from pcre.h.in, but the only changes that were
1235     made were to insert the current release number. This seemed silly, because
1236     it made things harder for people building PCRE on systems that don't run
1237     "configure". I have turned pcre.h into a distributed file, no longer built
1238     by "configure", with the version identification directly included. There is
1239     no longer a pcre.h.in file.
1240    
1241     However, this change necessitated a change to the pcre-config script as
1242     well. It is built from pcre-config.in, and one of the substitutions was the
1243     release number. I have updated configure.ac so that ./configure now finds
1244     the release number by grepping pcre.h.
1245    
1246     26. Added the ability to run the tests under valgrind.
1247    
1248    
1249 nigel 85 Version 6.4 05-Sep-05
1250     ---------------------
1251    
1252     1. Change 6.0/10/(l) to pcregrep introduced a bug that caused separator lines
1253     "--" to be printed when multiple files were scanned, even when none of the
1254     -A, -B, or -C options were used. This is not compatible with Gnu grep, so I
1255     consider it to be a bug, and have restored the previous behaviour.
1256    
1257     2. A couple of code tidies to get rid of compiler warnings.
1258    
1259     3. The pcretest program used to cheat by referring to symbols in the library
1260     whose names begin with _pcre_. These are internal symbols that are not
1261     really supposed to be visible externally, and in some environments it is
1262     possible to suppress them. The cheating is now confined to including
1263     certain files from the library's source, which is a bit cleaner.
1264    
1265     4. Renamed pcre.in as pcre.h.in to go with pcrecpp.h.in; it also makes the
1266     file's purpose clearer.
1267    
1268     5. Reorganized pcre_ucp_findchar().
1269    
1270    
1271 nigel 83 Version 6.3 15-Aug-05
1272     ---------------------
1273    
1274     1. The file libpcre.pc.in did not have general read permission in the tarball.
1275    
1276     2. There were some problems when building without C++ support:
1277    
1278     (a) If C++ support was not built, "make install" and "make test" still
1279     tried to test it.
1280    
1281     (b) There were problems when the value of CXX was explicitly set. Some
1282     changes have been made to try to fix these, and ...
1283    
1284     (c) --disable-cpp can now be used to explicitly disable C++ support.
1285    
1286     (d) The use of @CPP_OBJ@ directly caused a blank line preceded by a
1287     backslash in a target when C++ was disabled. This confuses some
1288     versions of "make", apparently. Using an intermediate variable solves
1289     this. (Same for CPP_LOBJ.)
1290    
1291     3. $(LINK_FOR_BUILD) now includes $(CFLAGS_FOR_BUILD) and $(LINK)
1292     (non-Windows) now includes $(CFLAGS) because these flags are sometimes
1293     necessary on certain architectures.
1294    
1295     4. Added a setting of -export-symbols-regex to the link command to remove
1296     those symbols that are exported in the C sense, but actually are local
1297     within the library, and not documented. Their names all begin with
1298     "_pcre_". This is not a perfect job, because (a) we have to except some
1299     symbols that pcretest ("illegally") uses, and (b) the facility isn't always
1300     available (and never for static libraries). I have made a note to try to
1301     find a way round (a) in the future.
1302    
1303    
1304 nigel 81 Version 6.2 01-Aug-05
1305     ---------------------
1306    
1307     1. There was no test for integer overflow of quantifier values. A construction
1308     such as {1111111111111111} would give undefined results. What is worse, if
1309     a minimum quantifier for a parenthesized subpattern overflowed and became
1310     negative, the calculation of the memory size went wrong. This could have
1311     led to memory overwriting.
1312    
1313     2. Building PCRE using VPATH was broken. Hopefully it is now fixed.
1314    
1315     3. Added "b" to the 2nd argument of fopen() in dftables.c, for non-Unix-like
1316     operating environments where this matters.
1317    
1318     4. Applied Giuseppe Maxia's patch to add additional features for controlling
1319     PCRE options from within the C++ wrapper.
1320    
1321     5. Named capturing subpatterns were not being correctly counted when a pattern
1322     was compiled. This caused two problems: (a) If there were more than 100
1323     such subpatterns, the calculation of the memory needed for the whole
1324     compiled pattern went wrong, leading to an overflow error. (b) Numerical
1325     back references of the form \12, where the number was greater than 9, were
1326     not recognized as back references, even though there were sufficient
1327     previous subpatterns.
1328    
1329     6. Two minor patches to pcrecpp.cc in order to allow it to compile on older
1330     versions of gcc, e.g. 2.95.4.
1331    
1332    
1333 nigel 79 Version 6.1 21-Jun-05
1334     ---------------------
1335    
1336     1. There was one reference to the variable "posix" in pcretest.c that was not
1337     surrounded by "#if !defined NOPOSIX".
1338    
1339     2. Make it possible to compile pcretest without DFA support, UTF8 support, or
1340     the cross-check on the old pcre_info() function, for the benefit of the
1341     cut-down version of PCRE that is currently imported into Exim.
1342    
1343     3. A (silly) pattern starting with (?i)(?-i) caused an internal space
1344     allocation error. I've done the easy fix, which wastes 2 bytes for sensible
1345     patterns that start (?i) but I don't think that matters. The use of (?i) is
1346     just an example; this all applies to the other options as well.
1347    
1348     4. Since libtool seems to echo the compile commands it is issuing, the output
1349     from "make" can be reduced a bit by putting "@" in front of each libtool
1350     compile command.
1351    
1352     5. Patch from the folks at Google for configure.in to be a bit more thorough
1353     in checking for a suitable C++ installation before trying to compile the
1354     C++ stuff. This should fix a reported problem when a compiler was present,
1355     but no suitable headers.
1356    
1357     6. The man pages all had just "PCRE" as their title. I have changed them to
1358     be the relevant file name. I have also arranged that these names are
1359     retained in the file doc/pcre.txt, which is a concatenation in text format
1360     of all the man pages except the little individual ones for each function.
1361    
1362     7. The NON-UNIX-USE file had not been updated for the different set of source
1363     files that come with release 6. I also added a few comments about the C++
1364     wrapper.
1365    
1366    
1367 nigel 77 Version 6.0 07-Jun-05
1368     ---------------------
1369    
1370     1. Some minor internal re-organization to help with my DFA experiments.
1371    
1372     2. Some missing #ifdef SUPPORT_UCP conditionals in pcretest and printint that
1373     didn't matter for the library itself when fully configured, but did matter
1374     when compiling without UCP support, or within Exim, where the ucp files are
1375     not imported.
1376    
1377     3. Refactoring of the library code to split up the various functions into
1378     different source modules. The addition of the new DFA matching code (see
1379     below) to a single monolithic source would have made it really too
1380     unwieldy, quite apart from causing all the code to be include in a
1381     statically linked application, when only some functions are used. This is
1382     relevant even without the DFA addition now that patterns can be compiled in
1383     one application and matched in another.
1384    
1385     The downside of splitting up is that there have to be some external
1386     functions and data tables that are used internally in different modules of
1387     the library but which are not part of the API. These have all had their
1388     names changed to start with "_pcre_" so that they are unlikely to clash
1389     with other external names.
1390    
1391     4. Added an alternate matching function, pcre_dfa_exec(), which matches using
1392     a different (DFA) algorithm. Although it is slower than the original
1393     function, it does have some advantages for certain types of matching
1394     problem.
1395    
1396     5. Upgrades to pcretest in order to test the features of pcre_dfa_exec(),
1397     including restarting after a partial match.
1398    
1399     6. A patch for pcregrep that defines INVALID_FILE_ATTRIBUTES if it is not
1400     defined when compiling for Windows was sent to me. I have put it into the
1401     code, though I have no means of testing or verifying it.
1402    
1403     7. Added the pcre_refcount() auxiliary function.
1404    
1405     8. Added the PCRE_FIRSTLINE option. This constrains an unanchored pattern to
1406     match before or at the first newline in the subject string. In pcretest,
1407     the /f option on a pattern can be used to set this.
1408    
1409     9. A repeated \w when used in UTF-8 mode with characters greater than 256
1410     would behave wrongly. This has been present in PCRE since release 4.0.
1411    
1412     10. A number of changes to the pcregrep command:
1413    
1414     (a) Refactored how -x works; insert ^(...)$ instead of setting
1415     PCRE_ANCHORED and checking the length, in preparation for adding
1416     something similar for -w.
1417    
1418     (b) Added the -w (match as a word) option.
1419    
1420     (c) Refactored the way lines are read and buffered so as to have more
1421     than one at a time available.
1422    
1423     (d) Implemented a pcregrep test script.
1424    
1425     (e) Added the -M (multiline match) option. This allows patterns to match
1426     over several lines of the subject. The buffering ensures that at least
1427     8K, or the rest of the document (whichever is the shorter) is available
1428     for matching (and similarly the previous 8K for lookbehind assertions).
1429    
1430     (f) Changed the --help output so that it now says
1431    
1432     -w, --word-regex(p)
1433    
1434     instead of two lines, one with "regex" and the other with "regexp"
1435     because that confused at least one person since the short forms are the
1436     same. (This required a bit of code, as the output is generated
1437     automatically from a table. It wasn't just a text change.)
1438    
1439     (g) -- can be used to terminate pcregrep options if the next thing isn't an
1440     option but starts with a hyphen. Could be a pattern or a path name
1441     starting with a hyphen, for instance.
1442    
1443     (h) "-" can be given as a file name to represent stdin.
1444    
1445     (i) When file names are being printed, "(standard input)" is used for
1446     the standard input, for compatibility with GNU grep. Previously
1447     "<stdin>" was used.
1448    
1449     (j) The option --label=xxx can be used to supply a name to be used for
1450     stdin when file names are being printed. There is no short form.
1451    
1452     (k) Re-factored the options decoding logic because we are going to add
1453     two more options that take data. Such options can now be given in four
1454     different ways, e.g. "-fname", "-f name", "--file=name", "--file name".
1455    
1456     (l) Added the -A, -B, and -C options for requesting that lines of context
1457     around matches be printed.
1458    
1459     (m) Added the -L option to print the names of files that do not contain
1460     any matching lines, that is, the complement of -l.
1461    
1462     (n) The return code is 2 if any file cannot be opened, but pcregrep does
1463     continue to scan other files.
1464    
1465     (o) The -s option was incorrectly implemented. For compatibility with other
1466     greps, it now suppresses the error message for a non-existent or non-
1467     accessible file (but not the return code). There is a new option called
1468     -q that suppresses the output of matching lines, which was what -s was
1469     previously doing.
1470    
1471     (p) Added --include and --exclude options to specify files for inclusion
1472     and exclusion when recursing.
1473    
1474     11. The Makefile was not using the Autoconf-supported LDFLAGS macro properly.
1475     Hopefully, it now does.
1476    
1477     12. Missing cast in pcre_study().
1478    
1479     13. Added an "uninstall" target to the makefile.
1480    
1481     14. Replaced "extern" in the function prototypes in Makefile.in with
1482     "PCRE_DATA_SCOPE", which defaults to 'extern' or 'extern "C"' in the Unix
1483     world, but is set differently for Windows.
1484    
1485     15. Added a second compiling function called pcre_compile2(). The only
1486     difference is that it has an extra argument, which is a pointer to an
1487     integer error code. When there is a compile-time failure, this is set
1488     non-zero, in addition to the error test pointer being set to point to an
1489     error message. The new argument may be NULL if no error number is required
1490     (but then you may as well call pcre_compile(), which is now just a
1491     wrapper). This facility is provided because some applications need a
1492     numeric error indication, but it has also enabled me to tidy up the way
1493     compile-time errors are handled in the POSIX wrapper.
1494    
1495     16. Added VPATH=.libs to the makefile; this should help when building with one
1496     prefix path and installing with another. (Or so I'm told by someone who
1497     knows more about this stuff than I do.)
1498    
1499     17. Added a new option, REG_DOTALL, to the POSIX function regcomp(). This
1500     passes PCRE_DOTALL to the pcre_compile() function, making the "." character
1501     match everything, including newlines. This is not POSIX-compatible, but
1502     somebody wanted the feature. From pcretest it can be activated by using
1503     both the P and the s flags.
1504    
1505     18. AC_PROG_LIBTOOL appeared twice in Makefile.in. Removed one.
1506    
1507     19. libpcre.pc was being incorrectly installed as executable.
1508    
1509     20. A couple of places in pcretest check for end-of-line by looking for '\n';
1510     it now also looks for '\r' so that it will work unmodified on Windows.
1511    
1512     21. Added Google's contributed C++ wrapper to the distribution.
1513    
1514     22. Added some untidy missing memory free() calls in pcretest, to keep
1515     Electric Fence happy when testing.
1516    
1517    
1518    
1519 nigel 75 Version 5.0 13-Sep-04
1520     ---------------------
1521    
1522     1. Internal change: literal characters are no longer packed up into items
1523     containing multiple characters in a single byte-string. Each character
1524     is now matched using a separate opcode. However, there may be more than one
1525     byte in the character in UTF-8 mode.
1526    
1527     2. The pcre_callout_block structure has two new fields: pattern_position and
1528     next_item_length. These contain the offset in the pattern to the next match
1529     item, and its length, respectively.
1530    
1531     3. The PCRE_AUTO_CALLOUT option for pcre_compile() requests the automatic
1532     insertion of callouts before each pattern item. Added the /C option to
1533     pcretest to make use of this.
1534    
1535     4. On the advice of a Windows user, the lines
1536    
1537     #if defined(_WIN32) || defined(WIN32)
1538     _setmode( _fileno( stdout ), 0x8000 );
1539     #endif /* defined(_WIN32) || defined(WIN32) */
1540    
1541     have been added to the source of pcretest. This apparently does useful
1542     magic in relation to line terminators.
1543    
1544     5. Changed "r" and "w" in the calls to fopen() in pcretest to "rb" and "wb"
1545     for the benefit of those environments where the "b" makes a difference.
1546    
1547     6. The icc compiler has the same options as gcc, but "configure" doesn't seem
1548     to know about it. I have put a hack into configure.in that adds in code
1549     to set GCC=yes if CC=icc. This seems to end up at a point in the
1550     generated configure script that is early enough to affect the setting of
1551     compiler options, which is what is needed, but I have no means of testing
1552     whether it really works. (The user who reported this had patched the
1553     generated configure script, which of course I cannot do.)
1554    
1555     LATER: After change 22 below (new libtool files), the configure script
1556     seems to know about icc (and also ecc). Therefore, I have commented out
1557     this hack in configure.in.
1558    
1559     7. Added support for pkg-config (2 patches were sent in).
1560    
1561     8. Negated POSIX character classes that used a combination of internal tables
1562     were completely broken. These were [[:^alpha:]], [[:^alnum:]], and
1563     [[:^ascii]]. Typically, they would match almost any characters. The other
1564     POSIX classes were not broken in this way.
1565    
1566     9. Matching the pattern "\b.*?" against "ab cd", starting at offset 1, failed
1567     to find the match, as PCRE was deluded into thinking that the match had to
1568     start at the start point or following a newline. The same bug applied to
1569     patterns with negative forward assertions or any backward assertions
1570     preceding ".*" at the start, unless the pattern required a fixed first
1571     character. This was a failing pattern: "(?!.bcd).*". The bug is now fixed.
1572    
1573     10. In UTF-8 mode, when moving forwards in the subject after a failed match
1574     starting at the last subject character, bytes beyond the end of the subject
1575     string were read.
1576    
1577     11. Renamed the variable "class" as "classbits" to make life easier for C++
1578     users. (Previously there was a macro definition, but it apparently wasn't
1579     enough.)
1580    
1581     12. Added the new field "tables" to the extra data so that tables can be passed
1582     in at exec time, or the internal tables can be re-selected. This allows
1583     a compiled regex to be saved and re-used at a later time by a different
1584     program that might have everything at different addresses.
1585    
1586     13. Modified the pcre-config script so that, when run on Solaris, it shows a
1587     -R library as well as a -L library.
1588    
1589     14. The debugging options of pcretest (-d on the command line or D on a
1590     pattern) showed incorrect output for anything following an extended class
1591     that contained multibyte characters and which was followed by a quantifier.
1592    
1593     15. Added optional support for general category Unicode character properties
1594     via the \p, \P, and \X escapes. Unicode property support implies UTF-8
1595     support. It adds about 90K to the size of the library. The meanings of the
1596     inbuilt class escapes such as \d and \s have NOT been changed.
1597    
1598     16. Updated pcredemo.c to include calls to free() to release the memory for the
1599     compiled pattern.
1600    
1601     17. The generated file chartables.c was being created in the source directory
1602     instead of in the building directory. This caused the build to fail if the
1603     source directory was different from the building directory, and was
1604     read-only.
1605    
1606     18. Added some sample Win commands from Mark Tetrode into the NON-UNIX-USE
1607     file. No doubt somebody will tell me if they don't make sense... Also added
1608     Dan Mooney's comments about building on OpenVMS.
1609    
1610     19. Added support for partial matching via the PCRE_PARTIAL option for
1611     pcre_exec() and the \P data escape in pcretest.
1612    
1613     20. Extended pcretest with 3 new pattern features:
1614    
1615     (i) A pattern option of the form ">rest-of-line" causes pcretest to
1616     write the compiled pattern to the file whose name is "rest-of-line".
1617     This is a straight binary dump of the data, with the saved pointer to
1618     the character tables forced to be NULL. The study data, if any, is
1619     written too. After writing, pcretest reads a new pattern.
1620    
1621     (ii) If, instead of a pattern, "<rest-of-line" is given, pcretest reads a
1622     compiled pattern from the given file. There must not be any
1623     occurrences of "<" in the file name (pretty unlikely); if there are,
1624     pcretest will instead treat the initial "<" as a pattern delimiter.
1625     After reading in the pattern, pcretest goes on to read data lines as
1626     usual.
1627    
1628     (iii) The F pattern option causes pcretest to flip the bytes in the 32-bit
1629     and 16-bit fields in a compiled pattern, to simulate a pattern that
1630     was compiled on a host of opposite endianness.
1631    
1632     21. The pcre-exec() function can now cope with patterns that were compiled on
1633     hosts of opposite endianness, with this restriction:
1634    
1635     As for any compiled expression that is saved and used later, the tables
1636     pointer field cannot be preserved; the extra_data field in the arguments
1637     to pcre_exec() should be used to pass in a tables address if a value
1638     other than the default internal tables were used at compile time.
1639    
1640     22. Calling pcre_exec() with a negative value of the "ovecsize" parameter is
1641     now diagnosed as an error. Previously, most of the time, a negative number
1642     would have been treated as zero, but if in addition "ovector" was passed as
1643     NULL, a crash could occur.
1644    
1645     23. Updated the files ltmain.sh, config.sub, config.guess, and aclocal.m4 with
1646     new versions from the libtool 1.5 distribution (the last one is a copy of
1647     a file called libtool.m4). This seems to have fixed the need to patch
1648     "configure" to support Darwin 1.3 (which I used to do). However, I still
1649     had to patch ltmain.sh to ensure that ${SED} is set (it isn't on my
1650     workstation).
1651    
1652     24. Changed the PCRE licence to be the more standard "BSD" licence.
1653    
1654    
1655 nigel 73 Version 4.5 01-Dec-03
1656     ---------------------
1657    
1658     1. There has been some re-arrangement of the code for the match() function so
1659     that it can be compiled in a version that does not call itself recursively.
1660     Instead, it keeps those local variables that need separate instances for
1661     each "recursion" in a frame on the heap, and gets/frees frames whenever it
1662     needs to "recurse". Keeping track of where control must go is done by means
1663     of setjmp/longjmp. The whole thing is implemented by a set of macros that
1664     hide most of the details from the main code, and operates only if
1665     NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the
1666     "configure" mechanism, "--disable-stack-for-recursion" turns on this way of
1667     operating.
1668    
1669     To make it easier for callers to provide specially tailored get/free
1670     functions for this usage, two new functions, pcre_stack_malloc, and
1671     pcre_stack_free, are used. They are always called in strict stacking order,
1672     and the size of block requested is always the same.
1673    
1674     The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether
1675     PCRE has been compiled to use the stack or the heap for recursion. The
1676     -C option of pcretest uses this to show which version is compiled.
1677    
1678     A new data escape \S, is added to pcretest; it causes the amounts of store
1679     obtained and freed by both kinds of malloc/free at match time to be added
1680     to the output.
1681    
1682     2. Changed the locale test to use "fr_FR" instead of "fr" because that's
1683     what's available on my current Linux desktop machine.
1684    
1685     3. When matching a UTF-8 string, the test for a valid string at the start has
1686     been extended. If start_offset is not zero, PCRE now checks that it points
1687     to a byte that is the start of a UTF-8 character. If not, it returns
1688     PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked;
1689     this is necessary because there may be backward assertions in the pattern.
1690     When matching the same subject several times, it may save resources to use
1691     PCRE_NO_UTF8_CHECK on all but the first call if the string is long.
1692    
1693     4. The code for checking the validity of UTF-8 strings has been tightened so
1694     that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings
1695     containing "overlong sequences".
1696    
1697     5. Fixed a bug (appearing twice) that I could not find any way of exploiting!
1698     I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&"
1699     should have been "&", but it just so happened that all the cases this let
1700     through by mistake were picked up later in the function.
1701    
1702     6. I had used a variable called "isblank" - this is a C99 function, causing
1703     some compilers to warn. To avoid this, I renamed it (as "blankclass").
1704    
1705     7. Cosmetic: (a) only output another newline at the end of pcretest if it is
1706     prompting; (b) run "./pcretest /dev/null" at the start of the test script
1707     so the version is shown; (c) stop "make test" echoing "./RunTest".
1708    
1709     8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems.
1710    
1711     9. The prototype for memmove() for systems that don't have it was using
1712     size_t, but the inclusion of the header that defines size_t was later. I've
1713     moved the #includes for the C headers earlier to avoid this.
1714    
1715     10. Added some adjustments to the code to make it easier to compiler on certain
1716     special systems:
1717    
1718     (a) Some "const" qualifiers were missing.
1719     (b) Added the macro EXPORT before all exported functions; by default this
1720     is defined to be empty.
1721     (c) Changed the dftables auxiliary program (that builds chartables.c) so
1722     that it reads its output file name as an argument instead of writing
1723     to the standard output and assuming this can be redirected.
1724    
1725     11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character
1726     class containing characters with values greater than 255, PCRE compilation
1727     went into a loop.
1728    
1729     12. A recursive reference to a subpattern that was within another subpattern
1730     that had a minimum quantifier of zero caused PCRE to crash. For example,
1731     (x(y(?2))z)? provoked this bug with a subject that got as far as the
1732     recursion. If the recursively-called subpattern itself had a zero repeat,
1733     that was OK.
1734    
1735     13. In pcretest, the buffer for reading a data line was set at 30K, but the
1736     buffer into which it was copied (for escape processing) was still set at
1737     1024, so long lines caused crashes.
1738    
1739     14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error
1740     "internal error: code overflow...". This applied to any character class
1741     that was followed by a possessive quantifier.
1742    
1743     15. Modified the Makefile to add libpcre.la as a prerequisite for
1744     libpcreposix.la because I was told this is needed for a parallel build to
1745     work.
1746    
1747     16. If a pattern that contained .* following optional items at the start was
1748     studied, the wrong optimizing data was generated, leading to matching
1749     errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any
1750     matching string must start with a or b or c. The correct conclusion for
1751     this pattern is that a match can start with any character.
1752    
1753    
1754 nigel 71 Version 4.4 13-Aug-03
1755     ---------------------
1756    
1757     1. In UTF-8 mode, a character class containing characters with values between
1758     127 and 255 was not handled correctly if the compiled pattern was studied.
1759     In fixing this, I have also improved the studying algorithm for such
1760     classes (slightly).
1761    
1762     2. Three internal functions had redundant arguments passed to them. Removal
1763     might give a very teeny performance improvement.
1764    
1765     3. Documentation bug: the value of the capture_top field in a callout is *one
1766     more than* the number of the hightest numbered captured substring.
1767    
1768     4. The Makefile linked pcretest and pcregrep with -lpcre, which could result
1769     in incorrectly linking with a previously installed version. They now link
1770     explicitly with libpcre.la.
1771    
1772     5. configure.in no longer needs to recognize Cygwin specially.
1773    
1774     6. A problem in pcre.in for Windows platforms is fixed.
1775    
1776     7. If a pattern was successfully studied, and the -d (or /D) flag was given to
1777     pcretest, it used to include the size of the study block as part of its
1778     output. Unfortunately, the structure contains a field that has a different
1779     size on different hardware architectures. This meant that the tests that
1780     showed this size failed. As the block is currently always of a fixed size,
1781     this information isn't actually particularly useful in pcretest output, so
1782     I have just removed it.
1783    
1784     8. Three pre-processor statements accidentally did not start in column 1.
1785     Sadly, there are *still* compilers around that complain, even though
1786     standard C has not required this for well over a decade. Sigh.
1787    
1788     9. In pcretest, the code for checking callouts passed small integers in the
1789     callout_data field, which is a void * field. However, some picky compilers
1790     complained about the casts involved for this on 64-bit systems. Now
1791     pcretest passes the address of the small integer instead, which should get
1792     rid of the warnings.
1793    
1794     10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at
1795     both compile and run time, and gives an error if an invalid UTF-8 sequence
1796     is found. There is a option for disabling this check in cases where the
1797     string is known to be correct and/or the maximum performance is wanted.
1798    
1799     11. In response to a bug report, I changed one line in Makefile.in from
1800    
1801     -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \
1802     to
1803     -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \
1804    
1805     to look similar to other lines, but I have no way of telling whether this
1806     is the right thing to do, as I do not use Windows. No doubt I'll get told
1807     if it's wrong...
1808    
1809    
1810 nigel 69 Version 4.3 21-May-03
1811     ---------------------
1812    
1813     1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the
1814     Makefile.
1815    
1816     2. Some refactoring to improve the quality of the code:
1817    
1818     (i) The utf8_table... variables are now declared "const".
1819    
1820     (ii) The code for \cx, which used the "case flipping" table to upper case
1821     lower case letters, now just substracts 32. This is ASCII-specific,
1822     but the whole concept of \cx is ASCII-specific, so it seems
1823     reasonable.
1824    
1825     (iii) PCRE was using its character types table to recognize decimal and
1826     hexadecimal digits in the pattern. This is silly, because it handles
1827     only 0-9, a-f, and A-F, but the character types table is locale-
1828     specific, which means strange things might happen. A private
1829     table is now used for this - though it costs 256 bytes, a table is
1830     much faster than multiple explicit tests. Of course, the standard
1831     character types table is still used for matching digits in subject
1832     strings against \d.
1833    
1834     (iv) Strictly, the identifier ESC_t is reserved by POSIX (all identifiers
1835     ending in _t are). So I've renamed it as ESC_tee.
1836    
1837     3. The first argument for regexec() in the POSIX wrapper should have been
1838     defined as "const".
1839    
1840     4. Changed pcretest to use malloc() for its buffers so that they can be
1841     Electric Fenced for debugging.
1842    
1843     5. There were several places in the code where, in UTF-8 mode, PCRE would try
1844     to read one or more bytes before the start of the subject string. Often this
1845     had no effect on PCRE's behaviour, but in some circumstances it could
1846     provoke a segmentation fault.
1847    
1848     6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE
1849     to try to read one or more bytes before the start of the subject string.
1850    
1851     7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with
1852     UTF-8 support could misbehave in various ways if the subject string
1853     contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind
1854     area. (PCRE was not checking for the UTF-8 mode flag, and trying to move
1855     back over UTF-8 characters.)
1856    
1857    
1858 nigel 67 Version 4.2 14-Apr-03
1859     ---------------------
1860    
1861     1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed.
1862    
1863     2. Changes to the building process, supplied by Ronald Landheer-Cieslak
1864     [ON_WINDOWS]: new variable, "#" on non-Windows platforms
1865     [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms
1866     [WIN_PREFIX]: new variable, "cyg" for Cygwin
1867     * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT
1868     and BUILD_EXEEXT
1869     Note: automatic setting of the BUILD variables is not yet working
1870     set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at
1871     compile-time but not at link-time
1872     [LINK]: use for linking executables only
1873     make different versions for Windows and non-Windows
1874     [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking
1875     libraries
1876     [LINK_FOR_BUILD]: new variable
1877     [OBJEXT]: use throughout
1878     [EXEEXT]: use throughout
1879     <winshared>: new target
1880     <wininstall>: new target
1881     <dftables.o>: use native compiler
1882     <dftables>: use native linker
1883     <install>: handle Windows platform correctly
1884     <clean>: ditto
1885     <check>: ditto
1886     copy DLL to top builddir before testing
1887    
1888     As part of these changes, -no-undefined was removed again. This was reported
1889     to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea
1890     in any case.
1891    
1892     3. Some tidies to get rid of compiler warnings:
1893    
1894     . In the match_data structure, match_limit was an unsigned long int, whereas
1895     match_call_count was an int. I've made them both unsigned long ints.
1896    
1897     . In pcretest the fact that a const uschar * doesn't automatically cast to
1898     a void * provoked a warning.
1899    
1900     . Turning on some more compiler warnings threw up some "shadow" variables
1901     and a few more missing casts.
1902    
1903     4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8
1904     option, a class that contained a single character with a value between 128
1905     and 255 (e.g. /[\xFF]/) caused PCRE to crash.
1906    
1907     5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8
1908     option, a class that contained several characters, but with at least one
1909     whose value was between 128 and 255 caused PCRE to crash.
1910    
1911    
1912 nigel 65 Version 4.1 12-Mar-03
1913     ---------------------
1914 nigel 63
1915 nigel 65 1. Compiling with gcc -pedantic found a couple of places where casts were
1916     needed, and a string in dftables.c that was longer than standard compilers are
1917     required to support.
1918    
1919     2. Compiling with Sun's compiler found a few more places where the code could
1920     be tidied up in order to avoid warnings.
1921    
1922     3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the
1923     first of these names is deprecated in the latest Autoconf in favour of the name
1924     CC_FOR_BUILD, because "host" is typically used to mean the system on which the
1925     compiled code will be run. I can't find a reference for HOST_CFLAGS, but by
1926     analogy I have changed it to CFLAGS_FOR_BUILD.
1927    
1928     4. Added -no-undefined to the linking command in the Makefile, because this is
1929     apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the
1930     linking step for the pcreposix library.
1931    
1932     5. PCRE was failing to diagnose the case of two named groups with the same
1933     name.
1934    
1935     6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a
1936     literal character that is needed in the subject for a match, and scans along to
1937     ensure that it is present before embarking on the full matching process. This
1938     saves time in cases of nested unlimited repeats that are never going to match.
1939     Problem: the scan can take a lot of time if the subject is very long (e.g.
1940     megabytes), thus penalizing straightforward matches. It is now done only if the
1941     amount of subject to be scanned is less than 1000 bytes.
1942    
1943     7. A lesser problem with the same optimization is that it was recording the
1944     first character of an anchored pattern as "needed", thus provoking a search
1945     right along the subject, even when the first match of the pattern was going to
1946     fail. The "needed" character is now not set for anchored patterns, unless it
1947     follows something in the pattern that is of non-fixed length. Thus, it still
1948     fulfils its original purpose of finding quick non-matches in cases of nested
1949     unlimited repeats, but isn't used for simple anchored patterns such as /^abc/.
1950    
1951    
1952     Version 4.0 17-Feb-03
1953     ---------------------
1954    
1955 nigel 63 1. If a comment in an extended regex that started immediately after a meta-item
1956     extended to the end of string, PCRE compiled incorrect data. This could lead to
1957     all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not.
1958    
1959     2. Moved to autoconf 2.53 and libtool 1.4.2.
1960    
1961     3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently,
1962     the special perltest8 script is no longer needed - all the tests can be run
1963     from a single perltest script.
1964    
1965     4. From 5.004, Perl has not included the VT character (0x0b) in the set defined
1966     by \s. It has now been removed in PCRE. This means it isn't recognized as
1967     whitespace in /x regexes too, which is the same as Perl. Note that the POSIX
1968     class [:space:] *does* include VT, thereby creating a mess.
1969    
1970     5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only
1971     space and tab.
1972    
1973     6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use
1974     its new features into the main test script, reducing the number of scripts.
1975    
1976     7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions
1977     were backward compatible, and made the (?i) apply to the whole pattern, as if
1978     /i were given. Now it behaves more logically, and applies the option setting
1979     only to what follows. PCRE has been changed to follow suit. However, if it
1980     finds options settings right at the start of the pattern, it extracts them into
1981     the global options, as before. Thus, they show up in the info data.
1982    
1983     8. Added support for the \Q...\E escape sequence. Characters in between are
1984     treated as literals. This is slightly different from Perl in that $ and @ are
1985     also handled as literals inside the quotes. In Perl, they will cause variable
1986     interpolation. Note the following examples:
1987    
1988     Pattern PCRE matches Perl matches
1989    
1990     \Qabc$xyz\E abc$xyz abc followed by the contents of $xyz
1991     \Qabc\$xyz\E abc\$xyz abc\$xyz
1992     \Qabc\E\$\Qxyz\E abc$xyz abc$xyz
1993    
1994     For compatibility with Perl, \Q...\E sequences are recognized inside character
1995     classes as well as outside them.
1996    
1997     9. Re-organized 3 code statements in pcretest to avoid "overflow in
1998     floating-point constant arithmetic" warnings from a Microsoft compiler. Added a
1999     (size_t) cast to one statement in pcretest and one in pcreposix to avoid
2000     signed/unsigned warnings.
2001    
2002     10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o
2003     option for pcretest, so I've replaced it by a simple function that does just
2004     that job.
2005    
2006     11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or
2007     "pcregrep -".
2008    
2009     12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's
2010     Java package. This provides some syntactic sugar for simple cases of what my
2011     documentation calls "once-only subpatterns". A pattern such as x*+ is the same
2012     as (?>x*). In other words, if what is inside (?>...) is just a single repeated
2013     item, you can use this simplified notation. Note that only makes sense with
2014     greedy quantifiers. Consequently, the use of the possessive quantifier forces
2015     greediness, whatever the setting of the PCRE_UNGREEDY option.
2016    
2017     13. A change of greediness default within a pattern was not taking effect at
2018     the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized
2019     subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option
2020     was abstracted outside.
2021    
2022     14. PCRE now supports the \G assertion. It is true when the current matching
2023     position is at the start point of the match. This differs from \A when the
2024     starting offset is non-zero. Used with the /g option of pcretest (or similar
2025     code), it works in the same way as it does for Perl's /g option. If all
2026     alternatives of a regex begin with \G, the expression is anchored to the start
2027     match position, and the "anchored" flag is set in the compiled expression.
2028    
2029     15. Some bugs concerning the handling of certain option changes within patterns
2030     have been fixed. These applied to options other than (?ims). For example,
2031     "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have
2032     been the other way round. Some of this was related to change 7 above.
2033    
2034     16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX
2035     features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/
2036     and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports
2037     POSIX classes only within a class (e.g. /[[:alpha:]]/).
2038    
2039     17. Added support for Perl's \C escape. This matches one byte, even in UTF8
2040     mode. Unlike ".", it always matches newline, whatever the setting of
2041     PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind
2042     assertions. Perl allows it, but it doesn't (in general) work because it can't
2043     calculate the length of the lookbehind. At least, that's the case for Perl
2044     5.8.0 - I've been told they are going to document that it doesn't work in
2045     future.
2046    
2047     18. Added an error diagnosis for escapes that PCRE does not support: these are
2048     \L, \l, \N, \P, \p, \U, \u, and \X.
2049    
2050     19. Although correctly diagnosing a missing ']' in a character class, PCRE was
2051     reading past the end of the pattern in cases such as /[abcd/.
2052    
2053     20. PCRE was getting more memory than necessary for patterns with classes that
2054     contained both POSIX named classes and other characters, e.g. /[[:space:]abc/.
2055    
2056     21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for
2057     compiling PCRE for use with Virtual Pascal.
2058    
2059     22. Small fix to the Makefile to make it work properly if the build is done
2060     outside the source tree.
2061    
2062     23. Added a new extension: a condition to go with recursion. If a conditional
2063     subpattern starts with (?(R) the "true" branch is used if recursion has
2064     happened, whereas the "false" branch is used only at the top level.
2065    
2066     24. When there was a very long string of literal characters (over 255 bytes
2067     without UTF support, over 250 bytes with UTF support), the computation of how
2068     much memory was required could be incorrect, leading to segfaults or other
2069     strange effects.
2070    
2071     25. PCRE was incorrectly assuming anchoring (either to start of subject or to
2072     start of line for a non-DOTALL pattern) when a pattern started with (.*) and
2073     there was a subsequent back reference to those brackets. This meant that, for
2074     example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't
2075     possible to check for precisely this case. All we can do is abandon the
2076     optimization if .* occurs inside capturing brackets when there are any back
2077     references whatsoever. (See below for a better fix that came later.)
2078    
2079     26. The handling of the optimization for finding the first character of a
2080     non-anchored pattern, and for finding a character that is required later in the
2081     match were failing in some cases. This didn't break the matching; it just
2082     failed to optimize when it could. The way this is done has been re-implemented.
2083    
2084     27. Fixed typo in error message for invalid (?R item (it said "(?p").
2085    
2086     28. Added a new feature that provides some of the functionality that Perl
2087     provides with (?{...}). The facility is termed a "callout". The way it is done
2088     in PCRE is for the caller to provide an optional function, by setting
2089     pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a
2090     global variable. By default it is unset, which disables all calling out. To get
2091     the function called, the regex must include (?C) at appropriate points. This
2092     is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C).
2093     This provides a means of identifying different callout points. When PCRE
2094     reaches such a point in the regex, if pcre_callout has been set, the external
2095     function is called. It is provided with data in a structure called
2096     pcre_callout_block, which is defined in pcre.h. If the function returns 0,
2097     matching continues; if it returns a non-zero value, the match at the current
2098     point fails. However, backtracking will occur if possible. [This was changed
2099     later and other features added - see item 49 below.]
2100    
2101     29. pcretest is upgraded to test the callout functionality. It provides a
2102     callout function that displays information. By default, it shows the start of
2103     the match and the current position in the text. There are some new data escapes
2104     to vary what happens:
2105    
2106     \C+ in addition, show current contents of captured substrings
2107     \C- do not supply a callout function
2108     \C!n return 1 when callout number n is reached
2109     \C!n!m return 1 when callout number n is reached for the mth time
2110    
2111     30. If pcregrep was called with the -l option and just a single file name, it
2112     output "<stdin>" if a match was found, instead of the file name.
2113    
2114     31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing
2115     slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to
2116     pcre_exec(). This saves a malloc/free per call. The default value of
2117     POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold
2118     when configuring.
2119    
2120     32. The default maximum size of a compiled pattern is 64K. There have been a
2121     few cases of people hitting this limit. The code now uses macros to handle the
2122     storing of links as offsets within the compiled pattern. It defaults to 2-byte
2123     links, but this can be changed to 3 or 4 bytes by --with-link-size when
2124     configuring. Tests 2 and 5 work only with 2-byte links because they output
2125     debugging information about compiled patterns.
2126    
2127     33. Internal code re-arrangements:
2128    
2129     (a) Moved the debugging function for printing out a compiled regex into
2130     its own source file (printint.c) and used #include to pull it into
2131     pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two
2132     separate copies.
2133    
2134     (b) Defined the list of op-code names for debugging as a macro in
2135     internal.h so that it is next to the definition of the opcodes.
2136    
2137     (c) Defined a table of op-code lengths for simpler skipping along compiled
2138     code. This is again a macro in internal.h so that it is next to the
2139     definition of the opcodes.
2140    
2141     34. Added support for recursive calls to individual subpatterns, along the
2142     lines of Robin Houston's patch (but implemented somewhat differently).
2143    
2144     35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to
2145     allow it to read and process whole directories in Win32. This code was
2146     contributed by Lionel Fourquaux; it has not been tested by me.
2147    
2148     36. Added support for named subpatterns. The Python syntax (?P<name>...) is
2149     used to name a group. Names consist of alphanumerics and underscores, and must
2150     be unique. Back references use the syntax (?P=name) and recursive calls use
2151     (?P>name) which is a PCRE extension to the Python extension. Groups still have
2152     numbers. The function pcre_fullinfo() can be used after compilation to extract
2153     a name/number map. There are three relevant calls:
2154    
2155     PCRE_INFO_NAMEENTRYSIZE yields the size of each entry in the map
2156     PCRE_INFO_NAMECOUNT yields the number of entries
2157     PCRE_INFO_NAMETABLE yields a pointer to the map.
2158    
2159     The map is a vector of fixed-size entries. The size of each entry depends on
2160     the length of the longest name used. The first two bytes of each entry are the
2161     group number, most significant byte first. There follows the corresponding
2162     name, zero terminated. The names are in alphabetical order.
2163    
2164     37. Make the maximum literal string in the compiled code 250 for the non-UTF-8
2165     case instead of 255. Making it the same both with and without UTF-8 support
2166     means that the same test output works with both.
2167    
2168     38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid
2169     calling malloc() with a zero argument.
2170    
2171     39. Change 25 above had to resort to a heavy-handed test for the .* anchoring
2172     optimization. I've improved things by keeping a bitmap of backreferences with
2173     numbers 1-31 so that if .* occurs inside capturing brackets that are not in
2174     fact referenced, the optimization can be applied. It is unlikely that a
2175     relevant occurrence of .* (i.e. one which might indicate anchoring or forcing
2176     the match to follow \n) will appear inside brackets with a number greater than
2177     31, but if it does, any back reference > 31 suppresses the optimization.
2178    
2179     40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect
2180     of disabling numbered capturing parentheses. Any opening parenthesis that is
2181     not followed by ? behaves as if it were followed by ?: but named parentheses
2182     can still be used for capturing (and they will acquire numbers in the usual
2183     way).
2184    
2185     41. Redesigned the return codes from the match() function into yes/no/error so
2186     that errors can be passed back from deep inside the nested calls. A malloc
2187     failure while inside a recursive subpattern call now causes the
2188     PCRE_ERROR_NOMEMORY return instead of quietly going wrong.
2189    
2190     42. It is now possible to set a limit on the number of times the match()
2191     function is called in a call to pcre_exec(). This facility makes it possible to
2192     limit the amount of recursion and backtracking, though not in a directly
2193     obvious way, because the match() function is used in a number of different
2194     circumstances. The count starts from zero for each position in the subject
2195     string (for non-anchored patterns). The default limit is, for compatibility, a
2196     large number, namely 10 000 000. You can change this in two ways:
2197    
2198     (a) When configuring PCRE before making, you can use --with-match-limit=n
2199     to set a default value for the compiled library.
2200    
2201     (b) For each call to pcre_exec(), you can pass a pcre_extra block in which
2202     a different value is set. See 45 below.
2203    
2204     If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT.
2205    
2206     43. Added a new function pcre_config(int, void *) to enable run-time extraction
2207     of things that can be changed at compile time. The first argument specifies
2208     what is wanted and the second points to where the information is to be placed.
2209     The current list of available information is:
2210    
2211     PCRE_CONFIG_UTF8
2212    
2213     The output is an integer that is set to one if UTF-8 support is available;
2214     otherwise it is set to zero.
2215    
2216     PCRE_CONFIG_NEWLINE
2217    
2218     The output is an integer that it set to the value of the code that is used for
2219     newline. It is either LF (10) or CR (13).
2220    
2221     PCRE_CONFIG_LINK_SIZE
2222    
2223     The output is an integer that contains the number of bytes used for internal
2224     linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above.
2225    
2226     PCRE_CONFIG_POSIX_MALLOC_THRESHOLD
2227    
2228     The output is an integer that contains the threshold above which the POSIX
2229     interface uses malloc() for output vectors. See item 31 above.
2230    
2231     PCRE_CONFIG_MATCH_LIMIT
2232    
2233     The output is an unsigned integer that contains the default limit of the number
2234     of match() calls in a pcre_exec() execution. See 42 above.
2235    
2236     44. pcretest has been upgraded by the addition of the -C option. This causes it
2237     to extract all the available output from the new pcre_config() function, and to
2238     output it. The program then exits immediately.
2239    
2240     45. A need has arisen to pass over additional data with calls to pcre_exec() in
2241     order to support additional features. One way would have been to define
2242     pcre_exec2() (for example) with extra arguments, but this would not have been
2243     extensible, and would also have required all calls to the original function to
2244     be mapped to the new one. Instead, I have chosen to extend the mechanism that
2245     is used for passing in "extra" data from pcre_study().
2246    
2247     The pcre_extra structure is now exposed and defined in pcre.h. It currently
2248     contains the following fields:
2249    
2250     flags a bitmap indicating which of the following fields are set
2251     study_data opaque data from pcre_study()
2252     match_limit a way of specifying a limit on match() calls for a specific
2253     call to pcre_exec()
2254     callout_data data for callouts (see 49 below)
2255    
2256     The flag bits are also defined in pcre.h, and are
2257    
2258     PCRE_EXTRA_STUDY_DATA
2259     PCRE_EXTRA_MATCH_LIMIT
2260     PCRE_EXTRA_CALLOUT_DATA
2261    
2262     The pcre_study() function now returns one of these new pcre_extra blocks, with
2263     the actual study data pointed to by the study_data field, and the
2264     PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as
2265     before. That is, this change is entirely upwards-compatible and requires no
2266     change to existing code.
2267    
2268     If you want to pass in additional data to pcre_exec(), you can either place it
2269     in a pcre_extra block provided by pcre_study(), or create your own pcre_extra
2270     block.
2271    
2272     46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a
2273     data string contains the escape sequence \M, pcretest calls pcre_exec() several
2274     times with different match limits, until it finds the minimum value needed for
2275     pcre_exec() to complete. The value is then output. This can be instructive; for
2276     most simple matches the number is quite small, but for pathological cases it
2277     gets very large very quickly.
2278    
2279     47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It
2280     returns the size of the data block pointed to by the study_data field in a
2281     pcre_extra block, that is, the value that was passed as the argument to
2282     pcre_malloc() when PCRE was getting memory in which to place the information
2283     created by pcre_study(). The fourth argument should point to a size_t variable.
2284     pcretest has been extended so that this information is shown after a successful
2285     pcre_study() call when information about the compiled regex is being displayed.
2286    
2287     48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR)
2288     because what follows is always an absolute path. (Later: it turns out that this
2289     is more than cosmetic for MinGW, because it doesn't like empty path
2290     components.)
2291    
2292     49. Some changes have been made to the callout feature (see 28 above):
2293    
2294     (i) A callout function now has three choices for what it returns:
2295    
2296     0 => success, carry on matching
2297     > 0 => failure at this point, but backtrack if possible
2298     < 0 => serious error, return this value from pcre_exec()
2299    
2300     Negative values should normally be chosen from the set of PCRE_ERROR_xxx
2301     values. In particular, returning PCRE_ERROR_NOMATCH forces a standard
2302     "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for
2303     use by callout functions. It will never be used by PCRE itself.
2304    
2305     (ii) The pcre_extra structure (see 45 above) has a void * field called
2306     callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The
2307     pcre_callout_block structure has a field of the same name. The contents of
2308     the field passed in the pcre_extra structure are passed to the callout
2309     function in the corresponding field in the callout block. This makes it
2310     easier to use the same callout-containing regex from multiple threads. For
2311     testing, the pcretest program has a new data escape
2312    
2313     \C*n pass the number n (may be negative) as callout_data
2314    
2315     If the callout function in pcretest receives a non-zero value as
2316     callout_data, it returns that value.
2317    
2318     50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also,
2319     there were some redundant $(CFLAGS) in commands that are now specified as
2320     $(LINK), which already includes $(CFLAGS).
2321    
2322     51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE
2323     has been compiled with UTF-8 support *and* pcre_compile() has been compiled
2324     with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume
2325     one-byte characters throughout. Note that case-insensitive matching applies
2326     only to characters whose values are less than 256. PCRE doesn't support the
2327     notion of cases for higher-valued characters.
2328    
2329     (i) A character class whose characters are all within 0-255 is handled as
2330     a bit map, and the map is inverted for negative classes. Previously, a
2331     character > 255 always failed to match such a class; however it should
2332     match if the class was a negative one (e.g. [^ab]). This has been fixed.
2333    
2334     (ii) A negated character class with a single character < 255 is coded as
2335     "not this character" (OP_NOT). This wasn't working properly when the test
2336     character was multibyte, either singly or repeated.
2337    
2338     (iii) Repeats of multibyte characters are now handled correctly in UTF-8
2339     mode, for example: \x{100}{2,3}.
2340    
2341     (iv) The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either
2342     singly or repeated) now correctly test multibyte characters. However,
2343     PCRE doesn't recognize any characters with values greater than 255 as
2344     digits, spaces, or word characters. Such characters always match \D, \S,
2345     and \W, and never match \d, \s, or \w.
2346    
2347     (v) Classes may now contain characters and character ranges with values
2348     greater than 255. For example: [ab\x{100}-\x{400}].
2349    
2350     (vi) pcregrep now has a --utf-8 option (synonym -u) which makes it call
2351     PCRE in UTF-8 mode.
2352    
2353     52. The info request value PCRE_INFO_FIRSTCHAR has been renamed
2354     PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is
2355     retained for backwards compatibility. (Note that LASTLITERAL is also a byte
2356     value.)
2357    
2358     53. The single man page has become too large. I have therefore split it up into
2359     a number of separate man pages. These also give rise to individual HTML pages;
2360     these are now put in a separate directory, and there is an index.html page that
2361     lists them all. Some hyperlinking between the pages has been installed.
2362    
2363     54. Added convenience functions for handling named capturing parentheses.
2364    
2365     55. Unknown escapes inside character classes (e.g. [\M]) and escapes that
2366     aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also
2367     true in PCRE, except when the PCRE_EXTENDED option is set, in which case they
2368     are faulted.
2369    
2370     56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when
2371     calling configure. These values are used when compiling the dftables.c program
2372     which is run to generate the source of the default character tables. They
2373     default to the values of CC and CFLAGS. If you are cross-compiling PCRE,
2374     you will need to set these values.
2375    
2376     57. Updated the building process for Windows DLL, as provided by Fred Cox.
2377    
2378    
2379     Version 3.9 02-Jan-02
2380 nigel 61 ---------------------
2381    
2382     1. A bit of extraneous text had somehow crept into the pcregrep documentation.
2383    
2384     2. If --disable-static was given, the building process failed when trying to
2385     build pcretest and pcregrep. (For some reason it was using libtool to compile
2386     them, which is not right, as they aren't part of the library.)
2387    
2388    
2389 nigel 59 Version 3.8 18-Dec-01
2390     ---------------------
2391    
2392     1. The experimental UTF-8 code was completely screwed up. It was packing the
2393     bytes in the wrong order. How dumb can you get?
2394    
2395    
2396 nigel 57 Version 3.7 29-Oct-01
2397     ---------------------
2398    
2399     1. In updating pcretest to check change 1 of version 3.6, I screwed up.
2400     This caused pcretest, when used on the test data, to segfault. Unfortunately,
2401     this didn't happen under Solaris 8, where I normally test things.
2402    
2403 nigel 59 2. The Makefile had to be changed to make it work on BSD systems, where 'make'
2404     doesn't seem to recognize that ./xxx and xxx are the same file. (This entry
2405     isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made
2406     this fix an hour or so after the initial 3.7 release.)
2407 nigel 57
2408 nigel 59
2409 nigel 55 Version 3.6 23-Oct-01
2410     ---------------------
2411    
2412     1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if
2413     offsets passed as NULL with zero offset count.
2414    
2415     2. The config.guess and config.sub files had not been updated when I moved to
2416     the latest autoconf.
2417    
2418    
2419 nigel 53 Version 3.5 15-Aug-01
2420     ---------------------
2421 nigel 5
2422 nigel 53 1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that
2423     had been forgotten.
2424    
2425     2. By using declared but undefined structures, we can avoid using "void"
2426     definitions in pcre.h while keeping the internal definitions of the structures
2427     private.
2428    
2429     3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a
2430     user point of view, this means that both static and shared libraries are built
2431     by default, but this can be individually controlled. More of the work of
2432     handling this static/shared cases is now inside libtool instead of PCRE's make
2433     file.
2434    
2435     4. The pcretest utility is now installed along with pcregrep because it is
2436     useful for users (to test regexs) and by doing this, it automatically gets
2437     relinked by libtool. The documentation has been turned into a man page, so
2438     there are now .1, .txt, and .html versions in /doc.
2439    
2440     5. Upgrades to pcregrep:
2441     (i) Added long-form option names like gnu grep.
2442     (ii) Added --help to list all options with an explanatory phrase.
2443     (iii) Added -r, --recursive to recurse into sub-directories.
2444     (iv) Added -f, --file to read patterns from a file.
2445    
2446     6. pcre_exec() was referring to its "code" argument before testing that
2447     argument for NULL (and giving an error if it was NULL).
2448    
2449     7. Upgraded Makefile.in to allow for compiling in a different directory from
2450     the source directory.
2451    
2452     8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the
2453     options bits, the pointer it was passed was to an int instead of to an unsigned
2454     long int. This mattered only on 64-bit systems.
2455    
2456     9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is
2457     generated) instead of pcre.in, which it its source. Also made the same change
2458     in several of the .c files.
2459    
2460     10. A new release of gcc defines printf() as a macro, which broke pcretest
2461     because it had an ifdef in the middle of a string argument for printf(). Fixed
2462     by using separate calls to printf().
2463    
2464     11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure
2465     script, to force use of CR or LF instead of \n in the source. On non-Unix
2466     systems, the value can be set in config.h.
2467    
2468     12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an
2469     absolute limit. Changed the text of the error message to make this clear, and
2470     likewise updated the man page.
2471    
2472     13. The limit of 99 on the number of capturing subpatterns has been removed.
2473     The new limit is 65535, which I hope will not be a "real" limit.
2474    
2475    
2476 nigel 51 Version 3.4 22-Aug-00
2477     ---------------------
2478    
2479     1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *.
2480    
2481     2. Diagnose condition (?(0) as an error instead of crashing on matching.
2482    
2483    
2484 nigel 49 Version 3.3 01-Aug-00
2485     ---------------------
2486    
2487     1. If an octal character was given, but the value was greater than \377, it
2488     was not getting masked to the least significant bits, as documented. This could
2489     lead to crashes in some systems.
2490    
2491     2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats
2492     the hyphen as a literal. PCRE used to give an error; it now behaves like Perl.
2493    
2494     3. Added the functions pcre_free_substring() and pcre_free_substring_list().
2495     These just pass their arguments on to (pcre_free)(), but they are provided
2496     because some uses of PCRE bind it to non-C systems that can call its functions,
2497     but cannot call free() or pcre_free() directly.
2498    
2499     4. Add "make test" as a synonym for "make check". Corrected some comments in
2500     the Makefile.
2501    
2502     5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the
2503     Makefile.
2504    
2505     6. Changed the name of pgrep to pcregrep, because Solaris has introduced a
2506     command called pgrep for grepping around the active processes.
2507    
2508     7. Added the beginnings of support for UTF-8 character strings.
2509    
2510     8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and
2511     RANLIB to ./ltconfig so that they are used by libtool. I think these are all
2512     the relevant ones. (AR is not passed because ./ltconfig does its own figuring
2513     out for the ar command.)
2514    
2515    
2516 nigel 47 Version 3.2 12-May-00
2517     ---------------------
2518    
2519     This is purely a bug fixing release.
2520    
2521     1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead
2522     of ZA. This was just one example of several cases that could provoke this bug,
2523     which was introduced by change 9 of version 2.00. The code for breaking
2524     infinite loops after an iteration that matches an empty string was't working
2525     correctly.
2526    
2527     2. The pcretest program was not imitating Perl correctly for the pattern /a*/g
2528     when matched against abbab (for example). After matching an empty string, it
2529     wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this
2530     caused it to match further down the string than it should.
2531    
2532     3. The code contained an inclusion of sys/types.h. It isn't clear why this
2533     was there because it doesn't seem to be needed, and it causes trouble on some
2534     systems, as it is not a Standard C header. It has been removed.
2535    
2536     4. Made 4 silly changes to the source to avoid stupid compiler warnings that
2537     were reported on the Macintosh. The changes were from
2538    
2539     while ((c = *(++ptr)) != 0 && c != '\n');
2540     to
2541     while ((c = *(++ptr)) != 0 && c != '\n') ;
2542    
2543     Totally extraordinary, but if that's what it takes...
2544    
2545     5. PCRE is being used in one environment where neither memmove() nor bcopy() is
2546     available. Added HAVE_BCOPY and an autoconf test for it; if neither
2547     HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which
2548     assumes the way PCRE uses memmove() (always moving upwards).
2549    
2550     6. PCRE is being used in one environment where strchr() is not available. There
2551     was only one use in pcre.c, and writing it out to avoid strchr() probably gives
2552     faster code anyway.
2553    
2554    
2555 nigel 45 Version 3.1 09-Feb-00
2556     ---------------------
2557    
2558     The only change in this release is the fixing of some bugs in Makefile.in for
2559     the "install" target:
2560    
2561     (1) It was failing to install pcreposix.h.
2562    
2563     (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page.
2564    
2565    
2566 nigel 43 Version 3.0 01-Feb-00
2567     ---------------------
2568 nigel 41
2569     1. Add support for the /+ modifier to perltest (to output $` like it does in
2570     pcretest).
2571    
2572     2. Add support for the /g modifier to perltest.
2573    
2574     3. Fix pcretest so that it behaves even more like Perl for /g when the pattern
2575     matches null strings.
2576    
2577     4. Fix perltest so that it doesn't do unwanted things when fed an empty
2578     pattern. Perl treats empty patterns specially - it reuses the most recent
2579     pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this
2580     effect.
2581    
2582     5. The POSIX interface was broken in that it was just handing over the POSIX
2583     captured string vector to pcre_exec(), but (since release 2.00) PCRE has
2584     required a bigger vector, with some working space on the end. This means that
2585     the POSIX wrapper now has to get and free some memory, and copy the results.
2586    
2587 nigel 43 6. Added some simple autoconf support, placing the test data and the
2588     documentation in separate directories, re-organizing some of the
2589     information files, and making it build pcre-config (a GNU standard). Also added
2590     libtool support for building PCRE as a shared library, which is now the
2591     default.
2592 nigel 41
2593 nigel 43 7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and
2594     09 are not valid octal constants. Single digits will be used for minor values
2595     less than 10.
2596    
2597     8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that
2598     existing programs that set these in the POSIX interface can use PCRE without
2599     modification.
2600    
2601     9. Added a new function, pcre_fullinfo() with an extensible interface. It can
2602     return all that pcre_info() returns, plus additional data. The pcre_info()
2603     function is retained for compatibility, but is considered to be obsolete.
2604    
2605     10. Added experimental recursion feature (?R) to handle one common case that
2606     Perl 5.6 will be able to do with (?p{...}).
2607    
2608     11. Added support for POSIX character classes like [:alpha:], which Perl is
2609     adopting.
2610    
2611    
2612 nigel 39 Version 2.08 31-Aug-99
2613     ----------------------
2614    
2615     1. When startoffset was not zero and the pattern began with ".*", PCRE was not
2616     trying to match at the startoffset position, but instead was moving forward to
2617     the next newline as if a previous match had failed.
2618    
2619     2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G,
2620     and could get into a loop if a null string was matched other than at the start
2621     of the subject.
2622    
2623     3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can
2624     be distinguished at compile time, and for completeness also added PCRE_DATE.
2625    
2626     5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL
2627     in GnuWin32 environments.
2628    
2629    
2630 nigel 37 Version 2.07 29-Jul-99
2631     ----------------------
2632    
2633     1. The documentation is now supplied in plain text form and HTML as well as in
2634     the form of man page sources.
2635    
2636     2. C++ compilers don't like assigning (void *) values to other pointer types.
2637     In particular this affects malloc(). Although there is no problem in Standard
2638     C, I've put in casts to keep C++ compilers happy.
2639    
2640     3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call
2641     should be (const char *).
2642    
2643     4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may
2644     be useful for non-Unix systems who don't want to bother with the POSIX stuff.
2645     However, I haven't made this a standard facility. The documentation doesn't
2646     mention it, and the Makefile doesn't support it.
2647    
2648     5. The Makefile now contains an "install" target, with editable destinations at
2649     the top of the file. The pcretest program is not installed.
2650    
2651     6. pgrep -V now gives the PCRE version number and date.
2652    
2653     7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was
2654     causing the entire string to be ignored, instead of just the last character.
2655    
2656     8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a
2657     non-matching string, it can take a very, very long time, even for strings of
2658     quite modest length, because of the nested recursion. PCRE now does better in
2659     some of these cases. It does this by remembering the last required literal
2660     character in the pattern, and pre-searching the subject to ensure it is present
2661     before running the real match. In other words, it applies a heuristic to detect
2662     some types of certain failure quickly, and in the above example, if presented
2663     with a string that has no trailing " it gives "no match" very quickly.
2664    
2665     9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored;
2666     other alternatives are tried instead.
2667    
2668    
2669 nigel 35 Version 2.06 09-Jun-99
2670     ----------------------
2671    
2672     1. Change pcretest's output for amount of store used to show just the code
2673     space, because the remainder (the data block) varies in size between 32-bit and
2674     64-bit systems.
2675    
2676     2. Added an extra argument to pcre_exec() to supply an offset in the subject to
2677     start matching at. This allows lookbehinds to work when searching for multiple
2678     occurrences in a string.
2679    
2680     3. Added additional options to pcretest for testing multiple occurrences:
2681    
2682     /+ outputs the rest of the string that follows a match
2683     /g loops for multiple occurrences, using the new startoffset argument
2684     /G loops for multiple occurrences by passing an incremented pointer
2685    
2686     4. PCRE wasn't doing the "first character" optimization for patterns starting
2687     with \b or \B, though it was doing it for other lookbehind assertions. That is,
2688     it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with
2689     the letter 'x'. On long subject strings, this gives a significant speed-up.
2690    
2691    
2692 nigel 33 Version 2.05 21-Apr-99
2693     ----------------------
2694    
2695     1. Changed the type of magic_number from int to long int so that it works
2696     properly on 16-bit systems.
2697    
2698     2. Fixed a bug which caused patterns starting with .* not to work correctly
2699     when the subject string contained newline characters. PCRE was assuming
2700     anchoring for such patterns in all cases, which is not correct because .* will
2701     not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if
2702     DOTALL is set at top level; otherwise it knows that patterns starting with .*
2703     must be retried after every newline in the subject.
2704    
2705    
2706 nigel 31 Version 2.04 18-Feb-99
2707     ----------------------
2708    
2709     1. For parenthesized subpatterns with repeats whose minimum was zero, the
2710     computation of the store needed to hold the pattern was incorrect (too large).
2711     If such patterns were nested a few deep, this could multiply and become a real
2712     problem.
2713    
2714     2. Added /M option to pcretest to show the memory requirement of a specific
2715     pattern. Made -m a synonym of -s (which does this globally) for compatibility.
2716    
2717     3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being
2718     compiled in such a way that the backtracking after subsequent failure was
2719     pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of
2720     ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size.
2721    
2722    
2723 nigel 29 Version 2.03 02-Feb-99
2724     ----------------------
2725    
2726     1. Fixed typo and small mistake in man page.
2727    
2728 nigel 31 2. Added 4th condition (GPL supersedes if conflict) and created separate
2729     LICENCE file containing the conditions.
2730 nigel 29
2731     3. Updated pcretest so that patterns such as /abc\/def/ work like they do in
2732     Perl, that is the internal \ allows the delimiter to be included in the
2733     pattern. Locked out the use of \ as a delimiter. If \ immediately follows
2734     the final delimiter, add \ to the end of the pattern (to test the error).
2735    
2736     4. Added the convenience functions for extracting substrings after a successful
2737     match. Updated pcretest to make it able to test these functions.
2738    
2739    
2740 nigel 27 Version 2.02 14-Jan-99
2741     ----------------------
2742    
2743     1. Initialized the working variables associated with each extraction so that
2744     their saving and restoring doesn't refer to uninitialized store.
2745    
2746     2. Put dummy code into study.c in order to trick the optimizer of the IBM C
2747     compiler for OS/2 into generating correct code. Apparently IBM isn't going to
2748     fix the problem.
2749    
2750     3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution
2751     calls, and wasn't printing the correct value for compiling calls. Increased the
2752     default value of LOOPREPEAT, and the number of significant figures in the
2753     times.
2754    
2755     4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT.
2756    
2757     5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid
2758     a building problem on Windows NT with a FAT file system.
2759    
2760    
2761 nigel 25 Version 2.01 21-Oct-98
2762     ----------------------
2763    
2764     1. Changed the API for pcre_compile() to allow for the provision of a pointer
2765     to character tables built by pcre_maketables() in the current locale. If NULL
2766     is passed, the default tables are used.
2767    
2768    
2769 nigel 23 Version 2.00 24-Sep-98
2770 nigel 21 ----------------------
2771    
2772 nigel 23 1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable
2773     it any more.
2774    
2775     2. Allow quantification of (?>) groups, and make it work correctly.
2776    
2777     3. The first character computation wasn't working for (?>) groups.
2778    
2779     4. Correct the implementation of \Z (it is permitted to match on the \n at the
2780     end of the subject) and add 5.005's \z, which really does match only at the
2781     very end of the subject.
2782    
2783     5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater.
2784    
2785     6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and
2786     DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005
2787     localized options. All options to pcre_study() were also removed.
2788    
2789     7. Add other new features from 5.005:
2790    
2791     $(?<= positive lookbehind
2792     $(?<! negative lookbehind
2793     (?imsx-imsx) added the unsetting capability
2794     such a setting is global if at outer level; local otherwise
2795     (?imsx-imsx:) non-capturing groups with option setting
2796     (?(cond)re|re) conditional pattern matching
2797    
2798     A backreference to itself in a repeated group matches the previous
2799     captured string.
2800    
2801     8. General tidying up of studying (both automatic and via "study")
2802     consequential on the addition of new assertions.
2803    
2804     9. As in 5.005, unlimited repeated groups that could match an empty substring
2805     are no longer faulted at compile time. Instead, the loop is forcibly broken at
2806     runtime if any iteration does actually match an empty substring.
2807    
2808     10. Include the RunTest script in the distribution.
2809    
2810     11. Added tests from the Perl 5.005_02 distribution. This showed up a few
2811     discrepancies, some of which were old and were also with respect to 5.004. They
2812     have now been fixed.
2813    
2814    
2815     Version 1.09 28-Apr-98
2816     ----------------------
2817    
2818 nigel 21 1. A negated single character class followed by a quantifier with a minimum
2819     value of one (e.g. [^x]{1,6} ) was not compiled correctly. This could lead to
2820     program crashes, or just wrong answers. This did not apply to negated classes
2821     containing more than one character, or to minima other than one.
2822    
2823    
2824 nigel 19 Version 1.08 27-Mar-98
2825     ----------------------
2826    
2827     1. Add PCRE_UNGREEDY to invert the greediness of quantifiers.
2828    
2829     2. Add (?U) and (?X) to set PCRE_UNGREEDY and PCRE_EXTRA respectively. The
2830     latter must appear before anything that relies on it in the pattern.
2831    
2832    
2833 nigel 17 Version 1.07 16-Feb-98
2834     ----------------------
2835    
2836     1. A pattern such as /((a)*)*/ was not being diagnosed as in error (unlimited
2837     repeat of a potentially empty string).
2838    
2839    
2840 nigel 15 Version 1.06 23-Jan-98
2841     ----------------------
2842    
2843     1. Added Markus Oberhumer's little patches for C++.
2844    
2845     2. Literal strings longer than 255 characters were broken.
2846    
2847    
2848 nigel 13 Version 1.05 23-Dec-97
2849     ----------------------
2850    
2851     1. Negated character classes containing more than one character were failing if
2852     PCRE_CASELESS was set at run time.
2853    
2854    
2855 nigel 11 Version 1.04 19-Dec-97
2856     ----------------------
2857    
2858     1. Corrected the man page, where some "const" qualifiers had been omitted.
2859    
2860     2. Made debugging output print "{0,xxx}" instead of just "{,xxx}" to agree with
2861     input syntax.
2862    
2863     3. Fixed memory leak which occurred when a regex with back references was
2864     matched with an offsets vector that wasn't big enough. The temporary memory
2865     that is used in this case wasn't being freed if the match failed.
2866    
2867     4. Tidied pcretest to ensure it frees memory that it gets.
2868    
2869     5. Temporary memory was being obtained in the case where the passed offsets
2870     vector was exactly big enough.
2871    
2872     6. Corrected definition of offsetof() from change 5 below.
2873    
2874     7. I had screwed up change 6 below and broken the rules for the use of
2875     setjmp(). Now fixed.
2876    
2877    
2878 nigel 9 Version 1.03 18-Dec-97
2879     ----------------------
2880    
2881     1. A erroneous regex with a missing opening parenthesis was correctly
2882     diagnosed, but PCRE attempted to access brastack[-1], which could cause crashes
2883     on some systems.
2884    
2885     2. Replaced offsetof(real_pcre, code) by offsetof(real_pcre, code[0]) because
2886     it was reported that one broken compiler failed on the former because "code" is
2887     also an independent variable.
2888    
2889     3. The erroneous regex a[]b caused an array overrun reference.
2890    
2891     4. A regex ending with a one-character negative class (e.g. /[^k]$/) did not
2892     fail on data ending with that character. (It was going on too far, and checking
2893     the next character, typically a binary zero.) This was specific to the
2894     optimized code for single-character negative classes.
2895    
2896     5. Added a contributed patch from the TIN world which does the following:
2897    
2898     + Add an undef for memmove, in case the the system defines a macro for it.
2899    
2900     + Add a definition of offsetof(), in case there isn't one. (I don't know
2901     the reason behind this - offsetof() is part of the ANSI standard - but
2902     it does no harm).
2903    
2904     + Reduce the ifdef's in pcre.c using macro DPRINTF, thereby eliminating
2905     most of the places where whitespace preceded '#'. I have given up and
2906     allowed the remaining 2 cases to be at the margin.
2907    
2908     + Rename some variables in pcre to eliminate shadowing. This seems very
2909     pedantic, but does no harm, of course.
2910    
2911     6. Moved the call to setjmp() into its own function, to get rid of warnings
2912     from gcc -Wall, and avoided calling it at all unless PCRE_EXTRA is used.
2913    
2914     7. Constructs such as \d{8,} were compiling into the equivalent of
2915 nigel 11 \d{8}\d{0,65527} instead of \d{8}\d* which didn't make much difference to the
2916 nigel 9 outcome, but in this particular case used more store than had been allocated,
2917     which caused the bug to be discovered because it threw up an internal error.
2918    
2919     8. The debugging code in both pcre and pcretest for outputting the compiled
2920     form of a regex was going wrong in the case of back references followed by
2921     curly-bracketed repeats.
2922    
2923    
2924 nigel 7 Version 1.02 12-Dec-97
2925     ----------------------
2926    
2927     1. Typos in pcre.3 and comments in the source fixed.
2928    
2929     2. Applied a contributed patch to get rid of places where it used to remove
2930     'const' from variables, and fixed some signed/unsigned and uninitialized
2931     variable warnings.
2932    
2933     3. Added the "runtest" target to Makefile.
2934    
2935     4. Set default compiler flag to -O2 rather than just -O.
2936    
2937    
2938 nigel 5 Version 1.01 19-Nov-97
2939     ----------------------
2940    
2941     1. PCRE was failing to diagnose unlimited repeat of empty string for patterns
2942     like /([ab]*)*/, that is, for classes with more than one character in them.
2943    
2944     2. Likewise, it wasn't diagnosing patterns with "once-only" subpatterns, such
2945     as /((?>a*))*/ (a PCRE_EXTRA facility).
2946    
2947    
2948     Version 1.00 18-Nov-97
2949     ----------------------
2950    
2951     1. Added compile-time macros to support systems such as SunOS4 which don't have
2952     memmove() or strerror() but have other things that can be used instead.
2953    
2954     2. Arranged that "make clean" removes the executables.
2955    
2956    
2957 nigel 3 Version 0.99 27-Oct-97
2958     ----------------------
2959    
2960     1. Fixed bug in code for optimizing classes with only one character. It was
2961     initializing a 32-byte map regardless, which could cause it to run off the end
2962     of the memory it had got.
2963    
2964     2. Added, conditional on PCRE_EXTRA, the proposed (?>REGEX) construction.
2965    
2966    
2967     Version 0.98 22-Oct-97
2968     ----------------------
2969    
2970     1. Fixed bug in code for handling temporary memory usage when there are more
2971     back references than supplied space in the ovector. This could cause segfaults.
2972    
2973    
2974     Version 0.97 21-Oct-97
2975     ----------------------
2976    
2977     1. Added the \X "cut" facility, conditional on PCRE_EXTRA.
2978    
2979     2. Optimized negated single characters not to use a bit map.
2980    
2981     3. Brought error texts together as macro definitions; clarified some of them;
2982     fixed one that was wrong - it said "range out of order" when it meant "invalid
2983     escape sequence".
2984    
2985     4. Changed some char * arguments to const char *.
2986    
2987     5. Added PCRE_NOTBOL and PCRE_NOTEOL (from POSIX).
2988    
2989     6. Added the POSIX-style API wrapper in pcreposix.a and testing facilities in
2990     pcretest.
2991    
2992    
2993     Version 0.96 16-Oct-97
2994     ----------------------
2995    
2996     1. Added a simple "pgrep" utility to the distribution.
2997    
2998     2. Fixed an incompatibility with Perl: "{" is now treated as a normal character
2999     unless it appears in one of the precise forms "{ddd}", "{ddd,}", or "{ddd,ddd}"
3000     where "ddd" means "one or more decimal digits".
3001    
3002     3. Fixed serious bug. If a pattern had a back reference, but the call to
3003     pcre_exec() didn't supply a large enough ovector to record the related
3004     identifying subpattern, the match always failed. PCRE now remembers the number
3005     of the largest back reference, and gets some temporary memory in which to save
3006     the offsets during matching if necessary, in order to ensure that
3007     backreferences always work.
3008    
3009     4. Increased the compatibility with Perl in a number of ways:
3010    
3011     (a) . no longer matches \n by default; an option PCRE_DOTALL is provided
3012     to request this handling. The option can be set at compile or exec time.
3013    
3014     (b) $ matches before a terminating newline by default; an option
3015     PCRE_DOLLAR_ENDONLY is provided to override this (but not in multiline
3016     mode). The option can be set at compile or exec time.
3017    
3018     (c) The handling of \ followed by a digit other than 0 is now supposed to be
3019     the same as Perl's. If the decimal number it represents is less than 10
3020     or there aren't that many previous left capturing parentheses, an octal
3021     escape is read. Inside a character class, it's always an octal escape,
3022     even if it is a single digit.
3023    
3024     (d) An escaped but undefined alphabetic character is taken as a literal,
3025     unless PCRE_EXTRA is set. Currently this just reserves the remaining
3026     escapes.
3027    
3028     (e) {0} is now permitted. (The previous item is removed from the compiled
3029     pattern).
3030    
3031     5. Changed all the names of code files so that the basic parts are no longer
3032     than 10 characters, and abolished the teeny "globals.c" file.
3033    
3034     6. Changed the handling of character classes; they are now done with a 32-byte
3035     bit map always.
3036    
3037     7. Added the -d and /D options to pcretest to make it possible to look at the
3038     internals of compilation without having to recompile pcre.
3039    
3040    
3041     Version 0.95 23-Sep-97
3042     ----------------------
3043    
3044     1. Fixed bug in pre-pass concerning escaped "normal" characters such as \x5c or
3045     \x20 at the start of a run of normal characters. These were being treated as
3046     real characters, instead of the source characters being re-checked.
3047    
3048    
3049     Version 0.94 18-Sep-97
3050     ----------------------
3051    
3052     1. The functions are now thread-safe, with the caveat that the global variables
3053     containing pointers to malloc() and free() or alternative functions are the
3054     same for all threads.
3055    
3056     2. Get pcre_study() to generate a bitmap of initial characters for non-
3057     anchored patterns when this is possible, and use it if passed to pcre_exec().
3058    
3059    
3060     Version 0.93 15-Sep-97
3061     ----------------------
3062    
3063     1. /(b)|(:+)/ was computing an incorrect first character.
3064    
3065     2. Add pcre_study() to the API and the passing of pcre_extra to pcre_exec(),
3066     but not actually doing anything yet.
3067    
3068     3. Treat "-" characters in classes that cannot be part of ranges as literals,
3069     as Perl does (e.g. [-az] or [az-]).
3070    
3071     4. Set the anchored flag if a branch starts with .* or .*? because that tests
3072     all possible positions.
3073    
3074     5. Split up into different modules to avoid including unneeded functions in a
3075     compiled binary. However, compile and exec are still in one module. The "study"
3076     function is split off.
3077    
3078     6. The character tables are now in a separate module whose source is generated
3079     by an auxiliary program - but can then be edited by hand if required. There are
3080     now no calls to isalnum(), isspace(), isdigit(), isxdigit(), tolower() or
3081     toupper() in the code.
3082    
3083     7. Turn the malloc/free funtions variables into pcre_malloc and pcre_free and
3084     make them global. Abolish the function for setting them, as the caller can now
3085     set them directly.
3086    
3087    
3088     Version 0.92 11-Sep-97
3089     ----------------------
3090    
3091     1. A repeat with a fixed maximum and a minimum of 1 for an ordinary character
3092     (e.g. /a{1,3}/) was broken (I mis-optimized it).
3093    
3094     2. Caseless matching was not working in character classes if the characters in
3095     the pattern were in upper case.
3096    
3097     3. Make ranges like [W-c] work in the same way as Perl for caseless matching.
3098    
3099     4. Make PCRE_ANCHORED public and accept as a compile option.
3100    
3101     5. Add an options word to pcre_exec() and accept PCRE_ANCHORED and
3102     PCRE_CASELESS at run time. Add escapes \A and \I to pcretest to cause it to
3103     pass them.
3104    
3105     6. Give an error if bad option bits passed at compile or run time.
3106    
3107     7. Add PCRE_MULTILINE at compile and exec time, and (?m) as well. Add \M to
3108     pcretest to cause it to pass that flag.
3109    
3110     8. Add pcre_info(), to get the number of identifying subpatterns, the stored
3111     options, and the first character, if set.
3112    
3113     9. Recognize C+ or C{n,m} where n >= 1 as providing a fixed starting character.
3114    
3115    
3116     Version 0.91 10-Sep-97
3117     ----------------------
3118    
3119     1. PCRE was failing to diagnose unlimited repeats of subpatterns that could
3120     match the empty string as in /(a*)*/. It was looping and ultimately crashing.
3121    
3122     2. PCRE was looping on encountering an indefinitely repeated back reference to
3123     a subpattern that had matched an empty string, e.g. /(a|)\1*/. It now does what
3124     Perl does - treats the match as successful.
3125    
3126     ****

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