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Revision 240 - (hide annotations) (download)
Tue Sep 11 15:47:20 2007 UTC (7 years, 3 months ago) by ph10
File size: 141107 byte(s)
Refactoring to reduce the number of relocations in a shared library.

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

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