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Change Log for PCRE2 -------------------- Version 10.23 14-February-2017 ------------------------------ 1. Extended pcre2test with the utf8_input modifier so that it is able to generate all possible 16-bit and 32-bit code unit values in non-UTF modes. 2. In any wide-character mode (8-bit UTF or any 16-bit or 32-bit mode), without PCRE2_UCP set, a negative character type such as \D in a positive class should cause all characters greater than 255 to match, whatever else is in the class. There was a bug that caused this not to happen if a Unicode property item was added to such a class, for example [\D\P{Nd}] or [\W\pL]. 3. There has been a major re-factoring of the pcre2_compile.c file. Most syntax checking is now done in the pre-pass that identifies capturing groups. This has reduced the amount of duplication and made the code tidier. While doing this, some minor bugs and Perl incompatibilities were fixed, including: (a) \Q\E in the middle of a quantifier such as A+\Q\E+ is now ignored instead of giving an invalid quantifier error. (b) {0} can now be used after a group in a lookbehind assertion; previously this caused an "assertion is not fixed length" error. (c) Perl always treats (?(DEFINE) as a "define" group, even if a group with the name "DEFINE" exists. PCRE2 now does likewise. (d) A recursion condition test such as (?(R2)...) must now refer to an existing subpattern. (e) A conditional recursion test such as (?(R)...) misbehaved if there was a group whose name began with "R". (f) When testing zero-terminated patterns under valgrind, the terminating zero is now marked "no access". This catches bugs that would otherwise show up only with non-zero-terminated patterns. (g) A hyphen appearing immediately after a POSIX character class (for example /[[:ascii:]-z]/) now generates an error. Perl does accept this as a literal, but gives a warning, so it seems best to fail it in PCRE. (h) An empty \Q\E sequence may appear after a callout that precedes an assertion condition (it is, of course, ignored). One effect of the refactoring is that some error numbers and messages have changed, and the pattern offset given for compiling errors is not always the right-most character that has been read. In particular, for a variable-length lookbehind assertion it now points to the start of the assertion. Another change is that when a callout appears before a group, the "length of next pattern item" that is passed now just gives the length of the opening parenthesis item, not the length of the whole group. A length of zero is now given only for a callout at the end of the pattern. Automatic callouts are no longer inserted before and after explicit callouts in the pattern. A number of bugs in the refactored code were subsequently fixed during testing before release, but after the code was made available in the repository. Many of the bugs were discovered by fuzzing testing. Several of them were related to the change from assuming a zero-terminated pattern (which previously had required non-zero terminated strings to be copied). These bugs were never in fully released code, but are noted here for the record. (a) An overall recursion such as (?0) inside a lookbehind assertion was not being diagnosed as an error. (b) In utf mode, the length of a *MARK (or other verb) name was being checked in characters instead of code units, which could lead to bad code being compiled, leading to unpredictable behaviour. (c) In extended /x mode, characters whose code was greater than 255 caused a lookup outside one of the global tables. A similar bug existed for wide characters in *VERB names. (d) The amount of memory needed for a compiled pattern was miscalculated if a lookbehind contained more than one toplevel branch and the first branch was of length zero. (e) In UTF-8 or UTF-16 modes with PCRE2_EXTENDED (/x) set and a non-zero- terminated pattern, if a # comment ran on to the end of the pattern, one or more code units past the end were being read. (f) An unterminated repeat at the end of a non-zero-terminated pattern (e.g. "{2,2") could cause reading beyond the pattern. (g) When reading a callout string, if the end delimiter was at the end of the pattern one further code unit was read. (h) An unterminated number after \g' could cause reading beyond the pattern. (i) An insufficient memory size was being computed for compiling with PCRE2_AUTO_CALLOUT. (j) A conditional group with an assertion condition used more memory than was allowed for it during parsing, so too many of them could therefore overrun a buffer. (k) If parsing a pattern exactly filled the buffer, the internal test for overrun did not check when the final META_END item was added. (l) If a lookbehind contained a subroutine call, and the called group contained an option setting such as (?s), and the PCRE2_ANCHORED option was set, unpredictable behaviour could occur. The underlying bug was incorrect code and insufficient checking while searching for the end of the called subroutine in the parsed pattern. (m) Quantifiers following (*VERB)s were not being diagnosed as errors. (n) The use of \Q...\E in a (*VERB) name when PCRE2_ALT_VERBNAMES and PCRE2_AUTO_CALLOUT were both specified caused undetermined behaviour. (o) If \Q was preceded by a quantified item, and the following \E was followed by '?' or '+', and there was at least one literal character between them, an internal error "unexpected repeat" occurred (example: /.+\QX\E+/). (p) A buffer overflow could occur while sorting the names in the group name list (depending on the order in which the names were seen). (q) A conditional group that started with a callout was not doing the right check for a following assertion, leading to compiling bad code. Example: /(?(C'XX))?!XX/ (r) If a character whose code point was greater than 0xffff appeared within a lookbehind that was within another lookbehind, the calculation of the lookbehind length went wrong and could provoke an internal error. (t) The sequence \E- or \Q\E- after a POSIX class in a character class caused an internal error. Now the hyphen is treated as a literal. 4. Back references are now permitted in lookbehind assertions when there are no duplicated group numbers (that is, (?| has not been used), and, if the reference is by name, there is only one group of that name. The referenced group must, of course be of fixed length. 5. pcre2test has been upgraded so that, when run under valgrind with valgrind support enabled, reading past the end of the pattern is detected, both when compiling and during callout processing. 6. \g{+<number>} (e.g. \g{+2} ) is now supported. It is a "forward back reference" and can be useful in repetitions (compare \g{-<number>} ). Perl does not recognize this syntax. 7. Automatic callouts are no longer generated before and after callouts in the pattern. 8. When pcre2test was outputing information from a callout, the caret indicator for the current position in the subject line was incorrect if it was after an escape sequence for a character whose code point was greater than \x{ff}. 9. Change 19 for 10.22 had a typo (PCRE_STATIC_RUNTIME should be PCRE2_STATIC_RUNTIME). Fix from David Gaussmann. 10. Added --max-buffer-size to pcre2grep, to allow for automatic buffer expansion when long lines are encountered. Original patch by Dmitry Cherniachenko. 11. If pcre2grep was compiled with JIT support, but the library was compiled without it (something that neither ./configure nor CMake allow, but it can be done by editing config.h), pcre2grep was giving a JIT error. Now it detects this situation and does not try to use JIT. 12. Added some "const" qualifiers to variables in pcre2grep. 13. Added Dmitry Cherniachenko's patch for colouring output in Windows (untested by me). Also, look for GREP_COLOUR or GREP_COLOR if the environment variables PCRE2GREP_COLOUR and PCRE2GREP_COLOR are not found. 14. Add the -t (grand total) option to pcre2grep. 15. A number of bugs have been mended relating to match start-up optimizations when the first thing in a pattern is a positive lookahead. These all applied only when PCRE2_NO_START_OPTIMIZE was *not* set: (a) A pattern such as (?=.*X)X$ was incorrectly optimized as if it needed both an initial 'X' and a following 'X'. (b) Some patterns starting with an assertion that started with .* were incorrectly optimized as having to match at the start of the subject or after a newline. There are cases where this is not true, for example, (?=.*[A-Z])(?=.{8,16})(?!.*[\s]) matches after the start in lines that start with spaces. Starting .* in an assertion is no longer taken as an indication of matching at the start (or after a newline). 16. The "offset" modifier in pcre2test was not being ignored (as documented) when the POSIX API was in use. 17. Added --enable-fuzz-support to "configure", causing an non-installed library containing a test function that can be called by fuzzers to be compiled. A non-installed binary to run the test function locally, called pcre2fuzzcheck is also compiled. 18. A pattern with PCRE2_DOTALL (/s) set but not PCRE2_NO_DOTSTAR_ANCHOR, and which started with .* inside a positive lookahead was incorrectly being compiled as implicitly anchored. 19. Removed all instances of "register" declarations, as they are considered obsolete these days and in any case had become very haphazard. 20. Add strerror() to pcre2test for failed file opening. 21. Make pcre2test -C list valgrind support when it is enabled. 22. Add the use_length modifier to pcre2test. 23. Fix an off-by-one bug in pcre2test for the list of names for 'get' and 'copy' modifiers. 24. Add PCRE2_CALL_CONVENTION into the prototype declarations in pcre2.h as it is apparently needed there as well as in the function definitions. (Why did nobody ask for this in PCRE1?) 25. Change the _PCRE2_H and _PCRE2_UCP_H guard macros in the header files to PCRE2_H_IDEMPOTENT_GUARD and PCRE2_UCP_H_IDEMPOTENT_GUARD to be more standard compliant and unique. 26. pcre2-config --libs-posix was listing -lpcre2posix instead of -lpcre2-posix. Also, the CMake build process was building the library with the wrong name. 27. In pcre2test, give some offset information for errors in hex patterns. This uses the C99 formatting sequence %td, except for MSVC which doesn't support it - %lu is used instead. 28. Implemented pcre2_code_copy_with_tables(), and added pushtablescopy to pcre2test for testing it. 29. Fix small memory leak in pcre2test. 30. Fix out-of-bounds read for partial matching of /./ against an empty string when the newline type is CRLF. 31. Fix a bug in pcre2test that caused a crash when a locale was set either in the current pattern or a previous one and a wide character was matched. 32. The appearance of \p, \P, or \X in a substitution string when PCRE2_SUBSTITUTE_EXTENDED was set caused a segmentation fault (NULL dereference). 33. If the starting offset was specified as greater than the subject length in a call to pcre2_substitute() an out-of-bounds memory reference could occur. 34. When PCRE2 was compiled to use the heap instead of the stack for recursive calls to match(), a repeated minimizing caseless back reference, or a maximizing one where the two cases had different numbers of code units, followed by a caseful back reference, could lose the caselessness of the first repeated back reference (example: /(Z)(a)\2{1,2}?(?-i)\1X/i should match ZaAAZX but didn't). 35. When a pattern is too complicated, PCRE2 gives up trying to find a minimum matching length and just records zero. Typically this happens when there are too many nested or recursive back references. If the limit was reached in certain recursive cases it failed to be triggered and an internal error could be the result. 36. The pcre2_dfa_match() function now takes note of the recursion limit for the internal recursive calls that are used for lookrounds and recursions within the pattern. 37. More refactoring has got rid of the internal could_be_empty_branch() function (around 400 lines of code, including comments) by keeping track of could-be-emptiness as the pattern is compiled instead of scanning compiled groups. (This would have been much harder before the refactoring of #3 above.) This lifts a restriction on the number of branches in a group (more than about 1100 would give "pattern is too complicated"). 38. Add the "-ac" command line option to pcre2test as a synonym for "-pattern auto_callout". 39. In a library with Unicode support, incorrect data was compiled for a pattern with PCRE2_UCP set without PCRE2_UTF if a class required all wide characters to match (for example, /[\s[:^ascii:]]/). 40. The callout_error modifier has been added to pcre2test to make it possible to return PCRE2_ERROR_CALLOUT from a callout. 41. A minor change to pcre2grep: colour reset is now "<esc>[0m" instead of "<esc>[00m". 42. The limit in the auto-possessification code that was intended to catch overly-complicated patterns and not spend too much time auto-possessifying was being reset too often, resulting in very long compile times for some patterns. Now such patterns are no longer completely auto-possessified. 43. Applied Jason Hood's revised patch for RunTest.bat. 44. Added a new Windows script RunGrepTest.bat, courtesy of Jason Hood. 45. Minor cosmetic fix to pcre2test: move a variable that is not used under Windows into the "not Windows" code. 46. Applied Jason Hood's patches to upgrade pcre2grep under Windows and tidy some of the code: * normalised the Windows condition by ensuring WIN32 is defined; * enables the callout feature under Windows; * adds globbing (Microsoft's implementation expands quoted args), using a tweaked opendirectory; * implements the is_*_tty functions for Windows; * --color=always will write the ANSI sequences to file; * add sequences 4 (underline works on Win10) and 5 (blink as bright background, relatively standard on DOS/Win); * remove the (char *) casts for the now-const strings; * remove GREP_COLOUR (grep's command line allowed the 'u', but not the environment), parsing GREP_COLORS instead; * uses the current colour if not set, rather than black; * add print_match for the undefined case; * fixes a typo. In addition, colour settings containing anything other than digits and semicolon are ignored, and the colour controls are no longer output for empty strings. 47. Detecting patterns that are too large inside the length-measuring loop saves processing ridiculously long patterns to their end. 48. Ignore PCRE2_CASELESS when processing \h, \H, \v, and \V in classes as it just wastes time. In the UTF case it can also produce redundant entries in XCLASS lists caused by characters with multiple other cases and pairs of characters in the same "not-x" sublists. 49. A pattern such as /(?=(a\K))/ can report the end of the match being before its start; pcre2test was not handling this correctly when using the POSIX interface (it was OK with the native interface). 50. In pcre2grep, ignore all JIT compile errors. This means that pcre2grep will continue to work, falling back to interpretation if anything goes wrong with JIT. 51. Applied patches from Christian Persch to configure.ac to make use of the AC_USE_SYSTEM_EXTENSIONS macro and to test for functions used by the JIT modules. 52. Minor fixes to pcre2grep from Jason Hood: * fixed some spacing; * Windows doesn't usually use single quotes, so I've added a define to use appropriate quotes [in an example]; * LC_ALL was displayed as "LCC_ALL"; * numbers 11, 12 & 13 should end in "th"; * use double quotes in usage message. 53. When autopossessifying, skip empty branches without recursion, to reduce stack usage for the benefit of clang with -fsanitize-address, which uses huge stack frames. Example pattern: /X?(R||){3335}/. Fixes oss-fuzz issue 553. 54. A pattern with very many explicit back references to a group that is a long way from the start of the pattern could take a long time to compile because searching for the referenced group in order to find the minimum length was being done repeatedly. Now up to 128 group minimum lengths are cached and the attempt to find a minimum length is abandoned if there is a back reference to a group whose number is greater than 128. (In that case, the pattern is so complicated that this optimization probably isn't worth it.) This fixes oss-fuzz issue 557. 55. Issue 32 for 10.22 below was not correctly fixed. If pcre2grep in multiline mode with --only-matching matched several lines, it restarted scanning at the next line instead of moving on to the end of the matched string, which can be several lines after the start. 56. Applied Jason Hood's new patch for RunGrepTest.bat that updates it in line with updates to the non-Windows version. Version 10.22 29-July-2016 -------------------------- 1. Applied Jason Hood's patches to RunTest.bat and testdata/wintestoutput3 to fix problems with running the tests under Windows. 2. Implemented a facility for quoting literal characters within hexadecimal patterns in pcre2test, to make it easier to create patterns with just a few non-printing characters. 3. Binary zeros are not supported in pcre2test input files. It now detects them and gives an error. 4. Updated the valgrind parameters in RunTest: (a) changed smc-check=all to smc-check=all-non-file; (b) changed obj:* in the suppression file to obj:??? so that it matches only unknown objects. 5. Updated the maintenance script maint/ManyConfigTests to make it easier to select individual groups of tests. 6. When the POSIX wrapper function regcomp() is called, the REG_NOSUB option used to set PCRE2_NO_AUTO_CAPTURE when calling pcre2_compile(). However, this disables the use of back references (and subroutine calls), which are supported by other implementations of regcomp() with RE_NOSUB. Therefore, REG_NOSUB no longer causes PCRE2_NO_AUTO_CAPTURE to be set, though it still ignores nmatch and pmatch when regexec() is called. 7. Because of 6 above, pcre2test has been modified with a new modifier called posix_nosub, to call regcomp() with REG_NOSUB. Previously the no_auto_capture modifier had this effect. That option is now ignored when the POSIX API is in use. 8. Minor tidies to the pcre2demo.c sample program, including more comments about its 8-bit-ness. 9. Detect unmatched closing parentheses and give the error in the pre-scan instead of later. Previously the pre-scan carried on and could give a misleading incorrect error message. For example, /(?J)(?'a'))(?'a')/ gave a message about invalid duplicate group names. 10. It has happened that pcre2test was accidentally linked with another POSIX regex library instead of libpcre2-posix. In this situation, a call to regcomp() (in the other library) may succeed, returning zero, but of course putting its own data into the regex_t block. In one example the re_pcre2_code field was left as NULL, which made pcre2test think it had not got a compiled POSIX regex, so it treated the next line as another pattern line, resulting in a confusing error message. A check has been added to pcre2test to see if the data returned from a successful call of regcomp() are valid for PCRE2's regcomp(). If they are not, an error message is output and the pcre2test run is abandoned. The message points out the possibility of a mis-linking. Hopefully this will avoid some head-scratching the next time this happens. 11. A pattern such as /(?<=((?C)0))/, which has a callout inside a lookbehind assertion, caused pcre2test to output a very large number of spaces when the callout was taken, making the program appearing to loop. 12. A pattern that included (*ACCEPT) in the middle of a sufficiently deeply nested set of parentheses of sufficient size caused an overflow of the compiling workspace (which was diagnosed, but of course is not desirable). 13. Detect missing closing parentheses during the pre-pass for group identification. 14. Changed some integer variable types and put in a number of casts, following a report of compiler warnings from Visual Studio 2013 and a few tests with gcc's -Wconversion (which still throws up a lot). 15. Implemented pcre2_code_copy(), and added pushcopy and #popcopy to pcre2test for testing it. 16. Change 66 for 10.21 introduced the use of snprintf() in PCRE2's version of regerror(). When the error buffer is too small, my version of snprintf() puts a binary zero in the final byte. Bug #1801 seems to show that other versions do not do this, leading to bad output from pcre2test when it was checking for buffer overflow. It no longer assumes a binary zero at the end of a too-small regerror() buffer. 17. Fixed typo ("&&" for "&") in pcre2_study(). Fortunately, this could not actually affect anything, by sheer luck. 18. Two minor fixes for MSVC compilation: (a) removal of apparently incorrect "const" qualifiers in pcre2test and (b) defining snprintf as _snprintf for older MSVC compilers. This has been done both in src/pcre2_internal.h for most of the library, and also in src/pcre2posix.c, which no longer includes pcre2_internal.h (see 24 below). 19. Applied Chris Wilson's patch (Bugzilla #1681) to CMakeLists.txt for MSVC static compilation. Subsequently applied Chris Wilson's second patch, putting the first patch under a new option instead of being unconditional when PCRE_STATIC is set. 20. Updated pcre2grep to set stdout as binary when run under Windows, so as not to convert \r\n at the ends of reflected lines into \r\r\n. This required ensuring that other output that is written to stdout (e.g. file names) uses the appropriate line terminator: \r\n for Windows, \n otherwise. 21. When a line is too long for pcre2grep's internal buffer, show the maximum length in the error message. 22. Added support for string callouts to pcre2grep (Zoltan's patch with PH additions). 23. RunTest.bat was missing a "set type" line for test 22. 24. The pcre2posix.c file was including pcre2_internal.h, and using some "private" knowledge of the data structures. This is unnecessary; the code has been re-factored and no longer includes pcre2_internal.h. 25. A racing condition is fixed in JIT reported by Mozilla. 26. Minor code refactor to avoid "array subscript is below array bounds" compiler warning. 27. Minor code refactor to avoid "left shift of negative number" warning. 28. Add a bit more sanity checking to pcre2_serialize_decode() and document that it expects trusted data. 29. Fix typo in pcre2_jit_test.c 30. Due to an oversight, pcre2grep was not making use of JIT when available. This is now fixed. 31. The RunGrepTest script is updated to use the valgrind suppressions file when testing with JIT under valgrind (compare 10.21/51 below). The suppressions file is updated so that is now the same as for PCRE1: it suppresses the Memcheck warnings Addr16 and Cond in unknown objects (that is, JIT-compiled code). Also changed smc-check=all to smc-check=all-non-file as was done for RunTest (see 4 above). 32. Implemented the PCRE2_NO_JIT option for pcre2_match(). 33. Fix typo that gave a compiler error when JIT not supported. 34. Fix comment describing the returns from find_fixedlength(). 35. Fix potential negative index in pcre2test. 36. Calls to pcre2_get_error_message() with error numbers that are never returned by PCRE2 functions were returning empty strings. Now the error code PCRE2_ERROR_BADDATA is returned. A facility has been added to pcre2test to show the texts for given error numbers (i.e. to call pcre2_get_error_message() and display what it returns) and a few representative error codes are now checked in RunTest. 37. Added "&& !defined(__INTEL_COMPILER)" to the test for __GNUC__ in pcre2_match.c, in anticipation that this is needed for the same reason it was recently added to pcrecpp.cc in PCRE1. 38. Using -o with -M in pcre2grep could cause unnecessary repeated output when the match extended over a line boundary, as it tried to find more matches "on the same line" - but it was already over the end. 39. Allow \C in lookbehinds and DFA matching in UTF-32 mode (by converting it to the same code as '.' when PCRE2_DOTALL is set). 40. Fix two clang compiler warnings in pcre2test when only one code unit width is supported. 41. Upgrade RunTest to automatically re-run test 2 with a large (64M) stack if it fails when running the interpreter with a 16M stack (and if changing the stack size via pcre2test is possible). This avoids having to manually set a large stack size when testing with clang. 42. Fix register overwite in JIT when SSE2 acceleration is enabled. 43. Detect integer overflow in pcre2test pattern and data repetition counts. 44. In pcre2test, ignore "allcaptures" after DFA matching. 45. Fix unaligned accesses on x86. Patch by Marc Mutz. 46. Fix some more clang compiler warnings. Version 10.21 12-January-2016 ----------------------------- 1. Improve matching speed of patterns starting with + or * in JIT. 2. Use memchr() to find the first character in an unanchored match in 8-bit mode in the interpreter. This gives a significant speed improvement. 3. Removed a redundant copy of the opcode_possessify table in the pcre2_auto_possessify.c source. 4. Fix typos in dftables.c for z/OS. 5. Change 36 for 10.20 broke the handling of [[:>:]] and [[:<:]] in that processing them could involve a buffer overflow if the following character was an opening parenthesis. 6. Change 36 for 10.20 also introduced a bug in processing this pattern: /((?x)(*:0))#(?'/. Specifically: if a setting of (?x) was followed by a (*MARK) setting (which (*:0) is), then (?x) did not get unset at the end of its group during the scan for named groups, and hence the external # was incorrectly treated as a comment and the invalid (?' at the end of the pattern was not diagnosed. This caused a buffer overflow during the real compile. This bug was discovered by Karl Skomski with the LLVM fuzzer. 7. Moved the pcre2_find_bracket() function from src/pcre2_compile.c into its own source module to avoid a circular dependency between src/pcre2_compile.c and src/pcre2_study.c 8. A callout with a string argument containing an opening square bracket, for example /(?C$[$)(?<]/, was incorrectly processed and could provoke a buffer overflow. This bug was discovered by Karl Skomski with the LLVM fuzzer. 9. The handling of callouts during the pre-pass for named group identification has been tightened up. 10. The quantifier {1} can be ignored, whether greedy, non-greedy, or possessive. This is a very minor optimization. 11. A possessively repeated conditional group that could match an empty string, for example, /(?(R))*+/, was incorrectly compiled. 12. The Unicode tables have been updated to Unicode 8.0.0 (thanks to Christian Persch). 13. An empty comment (?#) in a pattern was incorrectly processed and could provoke a buffer overflow. This bug was discovered by Karl Skomski with the LLVM fuzzer. 14. Fix infinite recursion in the JIT compiler when certain patterns such as /(?:|a|){100}x/ are analysed. 15. Some patterns with character classes involving [: and \\ were incorrectly compiled and could cause reading from uninitialized memory or an incorrect error diagnosis. Examples are: /[[:\\](?<[::]/ and /[[:\\](?'abc')[a:]. The first of these bugs was discovered by Karl Skomski with the LLVM fuzzer. 16. Pathological patterns containing many nested occurrences of [: caused pcre2_compile() to run for a very long time. This bug was found by the LLVM fuzzer. 17. A missing closing parenthesis for a callout with a string argument was not being diagnosed, possibly leading to a buffer overflow. This bug was found by the LLVM fuzzer. 18. A conditional group with only one branch has an implicit empty alternative branch and must therefore be treated as potentially matching an empty string. 19. If (?R was followed by - or + incorrect behaviour happened instead of a diagnostic. This bug was discovered by Karl Skomski with the LLVM fuzzer. 20. Another bug that was introduced by change 36 for 10.20: conditional groups whose condition was an assertion preceded by an explicit callout with a string argument might be incorrectly processed, especially if the string contained \Q. This bug was discovered by Karl Skomski with the LLVM fuzzer. 21. Compiling PCRE2 with the sanitize options of clang showed up a number of very pedantic coding infelicities and a buffer overflow while checking a UTF-8 string if the final multi-byte UTF-8 character was truncated. 22. For Perl compatibility in EBCDIC environments, ranges such as a-z in a class, where both values are literal letters in the same case, omit the non-letter EBCDIC code points within the range. 23. Finding the minimum matching length of complex patterns with back references and/or recursions can take a long time. There is now a cut-off that gives up trying to find a minimum length when things get too complex. 24. An optimization has been added that speeds up finding the minimum matching length for patterns containing repeated capturing groups or recursions. 25. If a pattern contained a back reference to a group whose number was duplicated as a result of appearing in a (?|...) group, the computation of the minimum matching length gave a wrong result, which could cause incorrect "no match" errors. For such patterns, a minimum matching length cannot at present be computed. 26. Added a check for integer overflow in conditions (?(<digits>) and (?(R<digits>). This omission was discovered by Karl Skomski with the LLVM fuzzer. 27. Fixed an issue when \p{Any} inside an xclass did not read the current character. 28. If pcre2grep was given the -q option with -c or -l, or when handling a binary file, it incorrectly wrote output to stdout. 29. The JIT compiler did not restore the control verb head in case of *THEN control verbs. This issue was found by Karl Skomski with a custom LLVM fuzzer. 30. The way recursive references such as (?3) are compiled has been re-written because the old way was the cause of many issues. Now, conversion of the group number into a pattern offset does not happen until the pattern has been completely compiled. This does mean that detection of all infinitely looping recursions is postponed till match time. In the past, some easy ones were detected at compile time. This re-writing was done in response to yet another bug found by the LLVM fuzzer. 31. A test for a back reference to a non-existent group was missing for items such as \987. This caused incorrect code to be compiled. This issue was found by Karl Skomski with a custom LLVM fuzzer. 32. Error messages for syntax errors following \g and \k were giving inaccurate offsets in the pattern. 33. Improve the performance of starting single character repetitions in JIT. 34. (*LIMIT_MATCH=) now gives an error instead of setting the value to 0. 35. Error messages for syntax errors in *LIMIT_MATCH and *LIMIT_RECURSION now give the right offset instead of zero. 36. The JIT compiler should not check repeats after a {0,1} repeat byte code. This issue was found by Karl Skomski with a custom LLVM fuzzer. 37. The JIT compiler should restore the control chain for empty possessive repeats. This issue was found by Karl Skomski with a custom LLVM fuzzer. 38. A bug which was introduced by the single character repetition optimization was fixed. 39. Match limit check added to recursion. This issue was found by Karl Skomski with a custom LLVM fuzzer. 40. Arrange for the UTF check in pcre2_match() and pcre2_dfa_match() to look only at the part of the subject that is relevant when the starting offset is non-zero. 41. Improve first character match in JIT with SSE2 on x86. 42. Fix two assertion fails in JIT. These issues were found by Karl Skomski with a custom LLVM fuzzer. 43. Correct the setting of CMAKE_C_FLAGS in CMakeLists.txt (patch from Roy Ivy III). 44. Fix bug in RunTest.bat for new test 14, and adjust the script for the added test (there are now 20 in total). 45. Fixed a corner case of range optimization in JIT. 46. Add the ${*MARK} facility to pcre2_substitute(). 47. Modifier lists in pcre2test were splitting at spaces without the required commas. 48. Implemented PCRE2_ALT_VERBNAMES. 49. Fixed two issues in JIT. These were found by Karl Skomski with a custom LLVM fuzzer. 50. The pcre2test program has been extended by adding the #newline_default command. This has made it possible to run the standard tests when PCRE2 is compiled with either CR or CRLF as the default newline convention. As part of this work, the new command was added to several test files and the testing scripts were modified. The pcre2grep tests can now also be run when there is no LF in the default newline convention. 51. The RunTest script has been modified so that, when JIT is used and valgrind is specified, a valgrind suppressions file is set up to ignore "Invalid read of size 16" errors because these are false positives when the hardware supports the SSE2 instruction set. 52. It is now possible to have comment lines amid the subject strings in pcre2test (and perltest.sh) input. 53. Implemented PCRE2_USE_OFFSET_LIMIT and pcre2_set_offset_limit(). 54. Add the null_context modifier to pcre2test so that calling pcre2_compile() and the matching functions with NULL contexts can be tested. 55. Implemented PCRE2_SUBSTITUTE_EXTENDED. 56. In a character class such as [\W\p{Any}] where both a negative-type escape ("not a word character") and a property escape were present, the property escape was being ignored. 57. Fixed integer overflow for patterns whose minimum matching length is very, very large. 58. Implemented --never-backslash-C. 59. Change 55 above introduced a bug by which certain patterns provoked the erroneous error "\ at end of pattern". 60. The special sequences [[:<:]] and [[:>:]] gave rise to incorrect compiling errors or other strange effects if compiled in UCP mode. Found with libFuzzer and AddressSanitizer. 61. Whitespace at the end of a pcre2test pattern line caused a spurious error message if there were only single-character modifiers. It should be ignored. 62. The use of PCRE2_NO_AUTO_CAPTURE could cause incorrect compilation results or segmentation errors for some patterns. Found with libFuzzer and AddressSanitizer. 63. Very long names in (*MARK) or (*THEN) etc. items could provoke a buffer overflow. 64. Improve error message for overly-complicated patterns. 65. Implemented an optional replication feature for patterns in pcre2test, to make it easier to test long repetitive patterns. The tests for 63 above are converted to use the new feature. 66. In the POSIX wrapper, if regerror() was given too small a buffer, it could misbehave. 67. In pcre2_substitute() in UTF mode, the UTF validity check on the replacement string was happening before the length setting when the replacement string was zero-terminated. 68. In pcre2_substitute() in UTF mode, PCRE2_NO_UTF_CHECK can be set for the second and subsequent calls to pcre2_match(). 69. There was no check for integer overflow for a replacement group number in pcre2_substitute(). An added check for a number greater than the largest group number in the pattern means this is not now needed. 70. The PCRE2-specific VERSION condition didn't work correctly if only one digit was given after the decimal point, or if more than two digits were given. It now works with one or two digits, and gives a compile time error if more are given. 71. In pcre2_substitute() there was the possibility of reading one code unit beyond the end of the replacement string. 72. The code for checking a subject's UTF-32 validity for a pattern with a lookbehind involved an out-of-bounds pointer, which could potentially cause trouble in some environments. 73. The maximum lookbehind length was incorrectly calculated for patterns such as /(?<=(a)(?-1))x/ which have a recursion within a backreference. 74. Give an error if a lookbehind assertion is longer than 65535 code units. 75. Give an error in pcre2_substitute() if a match ends before it starts (as a result of the use of \K). 76. Check the length of subpattern names and the names in (*MARK:xx) etc. dynamically to avoid the possibility of integer overflow. 77. Implement pcre2_set_max_pattern_length() so that programs can restrict the size of patterns that they are prepared to handle. 78. (*NO_AUTO_POSSESS) was not working. 79. Adding group information caching improves the speed of compiling when checking whether a group has a fixed length and/or could match an empty string, especially when recursion or subroutine calls are involved. However, this cannot be used when (?| is present in the pattern because the same number may be used for groups of different sizes. To catch runaway patterns in this situation, counts have been introduced to the functions that scan for empty branches or compute fixed lengths. 80. Allow for the possibility of the size of the nest_save structure not being a factor of the size of the compiling workspace (it currently is). 81. Check for integer overflow in minimum length calculation and cap it at 65535. 82. Small optimizations in code for finding the minimum matching length. 83. Lock out configuring for EBCDIC with non-8-bit libraries. 84. Test for error code <= 0 in regerror(). 85. Check for too many replacements (more than INT_MAX) in pcre2_substitute(). 86. Avoid the possibility of computing with an out-of-bounds pointer (though not dereferencing it) while handling lookbehind assertions. 87. Failure to get memory for the match data in regcomp() is now given as a regcomp() error instead of waiting for regexec() to pick it up. 88. In pcre2_substitute(), ensure that CRLF is not split when it is a valid newline sequence. 89. Paranoid check in regcomp() for bad error code from pcre2_compile(). 90. Run test 8 (internal offsets and code sizes) for link sizes 3 and 4 as well as for link size 2. 91. Document that JIT has a limit on pattern size, and give more information about JIT compile failures in pcre2test. 92. Implement PCRE2_INFO_HASBACKSLASHC. 93. Re-arrange valgrind support code in pcre2test to avoid spurious reports with JIT (possibly caused by SSE2?). 94. Support offset_limit in JIT. 95. A sequence such as [[:punct:]b] that is, a POSIX character class followed by a single ASCII character in a class item, was incorrectly compiled in UCP mode. The POSIX class got lost, but only if the single character followed it. 96. [:punct:] in UCP mode was matching some characters in the range 128-255 that should not have been matched. 97. If [:^ascii:] or [:^xdigit:] are present in a non-negated class, all characters with code points greater than 255 are in the class. When a Unicode property was also in the class (if PCRE2_UCP is set, escapes such as \w are turned into Unicode properties), wide characters were not correctly handled, and could fail to match. 98. In pcre2test, make the "startoffset" modifier a synonym of "offset", because it sets the "startoffset" parameter for pcre2_match(). 99. If PCRE2_AUTO_CALLOUT was set on a pattern that had a (?# comment between an item and its qualifier (for example, A(?#comment)?B) pcre2_compile() misbehaved. This bug was found by the LLVM fuzzer. 100. The error for an invalid UTF pattern string always gave the code unit offset as zero instead of where the invalidity was found. 101. Further to 97 above, negated classes such as [^[:^ascii:]\d] were also not working correctly in UCP mode. 102. Similar to 99 above, if an isolated \E was present between an item and its qualifier when PCRE2_AUTO_CALLOUT was set, pcre2_compile() misbehaved. This bug was found by the LLVM fuzzer. 103. The POSIX wrapper function regexec() crashed if the option REG_STARTEND was set when the pmatch argument was NULL. It now returns REG_INVARG. 104. Allow for up to 32-bit numbers in the ordin() function in pcre2grep. 105. An empty \Q\E sequence between an item and its qualifier caused pcre2_compile() to misbehave when auto callouts were enabled. This bug was found by the LLVM fuzzer. 106. If both PCRE2_ALT_VERBNAMES and PCRE2_EXTENDED were set, and a (*MARK) or other verb "name" ended with whitespace immediately before the closing parenthesis, pcre2_compile() misbehaved. Example: /(*:abc )/, but only when both those options were set. 107. In a number of places pcre2_compile() was not handling NULL characters correctly, and pcre2test with the "bincode" modifier was not always correctly displaying fields containing NULLS: (a) Within /x extended #-comments (b) Within the "name" part of (*MARK) and other *verbs (c) Within the text argument of a callout 108. If a pattern that was compiled with PCRE2_EXTENDED started with white space or a #-type comment that was followed by (?-x), which turns off PCRE2_EXTENDED, and there was no subsequent (?x) to turn it on again, pcre2_compile() assumed that (?-x) applied to the whole pattern and consequently mis-compiled it. This bug was found by the LLVM fuzzer. The fix for this bug means that a setting of any of the (?imsxJU) options at the start of a pattern is no longer transferred to the options that are returned by PCRE2_INFO_ALLOPTIONS. In fact, this was an anachronism that should have changed when the effects of those options were all moved to compile time. 109. An escaped closing parenthesis in the "name" part of a (*verb) when PCRE2_ALT_VERBNAMES was set caused pcre2_compile() to malfunction. This bug was found by the LLVM fuzzer. 110. Implemented PCRE2_SUBSTITUTE_UNSET_EMPTY, and updated pcre2test to make it possible to test it. 111. "Harden" pcre2test against ridiculously large values in modifiers and command line arguments. 112. Implemented PCRE2_SUBSTITUTE_UNKNOWN_UNSET and PCRE2_SUBSTITUTE_OVERFLOW_ LENGTH. 113. Fix printing of *MARK names that contain binary zeroes in pcre2test. Version 10.20 30-June-2015 -------------------------- 1. Callouts with string arguments have been added. 2. Assertion code generator in JIT has been optimized. 3. The invalid pattern (?(?C) has a missing assertion condition at the end. The pcre2_compile() function read past the end of the input before diagnosing an error. This bug was discovered by the LLVM fuzzer. 4. Implemented pcre2_callout_enumerate(). 5. Fix JIT compilation of conditional blocks whose assertion is converted to (*FAIL). E.g: /(?(?!))/. 6. The pattern /(?(?!)^)/ caused references to random memory. This bug was discovered by the LLVM fuzzer. 7. The assertion (?!) is optimized to (*FAIL). This was not handled correctly when this assertion was used as a condition, for example (?(?!)a|b). In pcre2_match() it worked by luck; in pcre2_dfa_match() it gave an incorrect error about an unsupported item. 8. For some types of pattern, for example /Z*(|d*){216}/, the auto- possessification code could take exponential time to complete. A recursion depth limit of 1000 has been imposed to limit the resources used by this optimization. This infelicity was discovered by the LLVM fuzzer. 9. A pattern such as /(*UTF)[\S\V\H]/, which contains a negated special class such as \S in non-UCP mode, explicit wide characters (> 255) can be ignored because \S ensures they are all in the class. The code for doing this was interacting badly with the code for computing the amount of space needed to compile the pattern, leading to a buffer overflow. This bug was discovered by the LLVM fuzzer. 10. A pattern such as /((?2)+)((?1))/ which has mutual recursion nested inside other kinds of group caused stack overflow at compile time. This bug was discovered by the LLVM fuzzer. 11. A pattern such as /(?1)(?#?'){8}(a)/ which had a parenthesized comment between a subroutine call and its quantifier was incorrectly compiled, leading to buffer overflow or other errors. This bug was discovered by the LLVM fuzzer. 12. The illegal pattern /(?(?<E>.*!.*)?)/ was not being diagnosed as missing an assertion after (?(. The code was failing to check the character after (?(?< for the ! or = that would indicate a lookbehind assertion. This bug was discovered by the LLVM fuzzer. 13. A pattern such as /X((?2)()*+){2}+/ which has a possessive quantifier with a fixed maximum following a group that contains a subroutine reference was incorrectly compiled and could trigger buffer overflow. This bug was discovered by the LLVM fuzzer. 14. Negative relative recursive references such as (?-7) to non-existent subpatterns were not being diagnosed and could lead to unpredictable behaviour. This bug was discovered by the LLVM fuzzer. 15. The bug fixed in 14 was due to an integer variable that was unsigned when it should have been signed. Some other "int" variables, having been checked, have either been changed to uint32_t or commented as "must be signed". 16. A mutual recursion within a lookbehind assertion such as (?<=((?2))((?1))) caused a stack overflow instead of the diagnosis of a non-fixed length lookbehind assertion. This bug was discovered by the LLVM fuzzer. 17. The use of \K in a positive lookbehind assertion in a non-anchored pattern (e.g. /(?<=\Ka)/) could make pcre2grep loop. 18. There was a similar problem to 17 in pcre2test for global matches, though the code there did catch the loop. 19. If a greedy quantified \X was preceded by \C in UTF mode (e.g. \C\X*), and a subsequent item in the pattern caused a non-match, backtracking over the repeated \X did not stop, but carried on past the start of the subject, causing reference to random memory and/or a segfault. There were also some other cases where backtracking after \C could crash. This set of bugs was discovered by the LLVM fuzzer. 20. The function for finding the minimum length of a matching string could take a very long time if mutual recursion was present many times in a pattern, for example, /((?2){73}(?2))((?1))/. A better mutual recursion detection method has been implemented. This infelicity was discovered by the LLVM fuzzer. 21. Implemented PCRE2_NEVER_BACKSLASH_C. 22. The feature for string replication in pcre2test could read from freed memory if the replication required a buffer to be extended, and it was not working properly in 16-bit and 32-bit modes. This issue was discovered by a fuzzer: see http://lcamtuf.coredump.cx/afl/. 23. Added the PCRE2_ALT_CIRCUMFLEX option. 24. Adjust the treatment of \8 and \9 to be the same as the current Perl behaviour. 25. Static linking against the PCRE2 library using the pkg-config module was failing on missing pthread symbols. 26. If a group that contained a recursive back reference also contained a forward reference subroutine call followed by a non-forward-reference subroutine call, for example /.((?2)(?R)\1)()/, pcre2_compile() failed to compile correct code, leading to undefined behaviour or an internally detected error. This bug was discovered by the LLVM fuzzer. 27. Quantification of certain items (e.g. atomic back references) could cause incorrect code to be compiled when recursive forward references were involved. For example, in this pattern: /(?1)()((((((\1++))\x85)+)|))/. This bug was discovered by the LLVM fuzzer. 28. A repeated conditional group whose condition was a reference by name caused a buffer overflow if there was more than one group with the given name. This bug was discovered by the LLVM fuzzer. 29. A recursive back reference by name within a group that had the same name as another group caused a buffer overflow. For example: /(?J)(?'d'(?'d'\g{d}))/. This bug was discovered by the LLVM fuzzer. 30. A forward reference by name to a group whose number is the same as the current group, for example in this pattern: /(?|(\k'Pm')|(?'Pm'))/, caused a buffer overflow at compile time. This bug was discovered by the LLVM fuzzer. 31. Fix -fsanitize=undefined warnings for left shifts of 1 by 31 (it treats 1 as an int; fixed by writing it as 1u). 32. Fix pcre2grep compile when -std=c99 is used with gcc, though it still gives a warning for "fileno" unless -std=gnu99 us used. 33. A lookbehind assertion within a set of mutually recursive subpatterns could provoke a buffer overflow. This bug was discovered by the LLVM fuzzer. 34. Give an error for an empty subpattern name such as (?''). 35. Make pcre2test give an error if a pattern that follows #forbud_utf contains \P, \p, or \X. 36. The way named subpatterns are handled has been refactored. There is now a pre-pass over the regex which does nothing other than identify named subpatterns and count the total captures. This means that information about named patterns is known before the rest of the compile. In particular, it means that forward references can be checked as they are encountered. Previously, the code for handling forward references was contorted and led to several errors in computing the memory requirements for some patterns, leading to buffer overflows. 37. There was no check for integer overflow in subroutine calls such as (?123). 38. The table entry for \l in EBCDIC environments was incorrect, leading to its being treated as a literal 'l' instead of causing an error. 39. If a non-capturing group containing a conditional group that could match an empty string was repeated, it was not identified as matching an empty string itself. For example: /^(?:(?(1)x|)+)+$()/. 40. In an EBCDIC environment, pcretest was mishandling the escape sequences \a and \e in test subject lines. 41. In an EBCDIC environment, \a in a pattern was converted to the ASCII instead of the EBCDIC value. 42. The handling of \c in an EBCDIC environment has been revised so that it is now compatible with the specification in Perl's perlebcdic page. 43. Single character repetition in JIT has been improved. 20-30% speedup was achieved on certain patterns. 44. The EBCDIC character 0x41 is a non-breaking space, equivalent to 0xa0 in ASCII/Unicode. This has now been added to the list of characters that are recognized as white space in EBCDIC. 45. When PCRE2 was compiled without Unicode support, the use of \p and \P gave an error (correctly) when used outside a class, but did not give an error within a class. 46. \h within a class was incorrectly compiled in EBCDIC environments. 47. JIT should return with error when the compiled pattern requires more stack space than the maximum. 48. Fixed a memory leak in pcre2grep when a locale is set. Version 10.10 06-March-2015 --------------------------- 1. When a pattern is compiled, it remembers the highest back reference so that when matching, if the ovector is too small, extra memory can be obtained to use instead. A conditional subpattern whose condition is a check on a capture having happened, such as, for example in the pattern /^(?:(a)|b)(?(1)A|B)/, is another kind of back reference, but it was not setting the highest backreference number. This mattered only if pcre2_match() was called with an ovector that was too small to hold the capture, and there was no other kind of back reference (a situation which is probably quite rare). The effect of the bug was that the condition was always treated as FALSE when the capture could not be consulted, leading to a incorrect behaviour by pcre2_match(). This bug has been fixed. 2. Functions for serialization and deserialization of sets of compiled patterns have been added. 3. The value that is returned by PCRE2_INFO_SIZE has been corrected to remove excess code units at the end of the data block that may occasionally occur if the code for calculating the size over-estimates. This change stops the serialization code copying uninitialized data, to which valgrind objects. The documentation of PCRE2_INFO_SIZE was incorrect in stating that the size did not include the general overhead. This has been corrected. 4. All code units in every slot in the table of group names are now set, again in order to avoid accessing uninitialized data when serializing. 5. The (*NO_JIT) feature is implemented. 6. If a bug that caused pcre2_compile() to use more memory than allocated was triggered when using valgrind, the code in (3) above passed a stupidly large value to valgrind. This caused a crash instead of an "internal error" return. 7. A reference to a duplicated named group (either a back reference or a test for being set in a conditional) that occurred in a part of the pattern where PCRE2_DUPNAMES was not set caused the amount of memory needed for the pattern to be incorrectly calculated, leading to overwriting. 8. A mutually recursive set of back references such as (\2)(\1) caused a segfault at compile time (while trying to find the minimum matching length). The infinite loop is now broken (with the minimum length unset, that is, zero). 9. If an assertion that was used as a condition was quantified with a minimum of zero, matching went wrong. In particular, if the whole group had unlimited repetition and could match an empty string, a segfault was likely. The pattern (?(?=0)?)+ is an example that caused this. Perl allows assertions to be quantified, but not if they are being used as conditions, so the above pattern is faulted by Perl. PCRE2 has now been changed so that it also rejects such patterns. 10. The error message for an invalid quantifier has been changed from "nothing to repeat" to "quantifier does not follow a repeatable item". 11. If a bad UTF string is compiled with NO_UTF_CHECK, it may succeed, but scanning the compiled pattern in subsequent auto-possessification can get out of step and lead to an unknown opcode. Previously this could have caused an infinite loop. Now it generates an "internal error" error. This is a tidyup, not a bug fix; passing bad UTF with NO_UTF_CHECK is documented as having an undefined outcome. 12. A UTF pattern containing a "not" match of a non-ASCII character and a subroutine reference could loop at compile time. Example: /[^\xff]((?1))/. 13. The locale test (RunTest 3) has been upgraded. It now checks that a locale that is found in the output of "locale -a" can actually be set by pcre2test before it is accepted. Previously, in an environment where a locale was listed but would not set (an example does exist), the test would "pass" without actually doing anything. Also the fr_CA locale has been added to the list of locales that can be used. 14. Fixed a bug in pcre2_substitute(). If a replacement string ended in a capturing group number without parentheses, the last character was incorrectly literally included at the end of the replacement string. 15. A possessive capturing group such as (a)*+ with a minimum repeat of zero failed to allow the zero-repeat case if pcre2_match() was called with an ovector too small to capture the group. 16. Improved error message in pcre2test when setting the stack size (-S) fails. 17. Fixed two bugs in CMakeLists.txt: (1) Some lines had got lost in the transfer from PCRE1, meaning that CMake configuration failed if "build tests" was selected. (2) The file src/pcre2_serialize.c had not been added to the list of PCRE2 sources, which caused a failure to build pcre2test. 18. Fixed typo in pcre2_serialize.c (DECL instead of DEFN) that causes problems only on Windows. 19. Use binary input when reading back saved serialized patterns in pcre2test. 20. Added RunTest.bat for running the tests under Windows. 21. "make distclean" was not removing config.h, a file that may be created for use with CMake. 22. A pattern such as "((?2){0,1999}())?", which has a group containing a forward reference repeated a large (but limited) number of times within a repeated outer group that has a zero minimum quantifier, caused incorrect code to be compiled, leading to the error "internal error: previously-checked referenced subpattern not found" when an incorrect memory address was read. This bug was reported as "heap overflow", discovered by Kai Lu of Fortinet's FortiGuard Labs. (Added 24-March-2015: CVE-2015-2325 was given to this.) 23. A pattern such as "((?+1)(\1))/" containing a forward reference subroutine call within a group that also contained a recursive back reference caused incorrect code to be compiled. This bug was reported as "heap overflow", discovered by Kai Lu of Fortinet's FortiGuard Labs. (Added 24-March-2015: CVE-2015-2326 was given to this.) 24. Computing the size of the JIT read-only data in advance has been a source of various issues, and new ones are still appear unfortunately. To fix existing and future issues, size computation is eliminated from the code, and replaced by on-demand memory allocation. 25. A pattern such as /(?i)[A-`]/, where characters in the other case are adjacent to the end of the range, and the range contained characters with more than one other case, caused incorrect behaviour when compiled in UTF mode. In that example, the range a-j was left out of the class. Version 10.00 05-January-2015 ----------------------------- Version 10.00 is the first release of PCRE2, a revised API for the PCRE library. Changes prior to 10.00 are logged in the ChangeLog file for the old API, up to item 20 for release 8.36. The code of the library was heavily revised as part of the new API implementation. Details of each and every modification were not individually logged. In addition to the API changes, the following changes were made. They are either new functionality, or bug fixes and other noticeable changes of behaviour that were implemented after the code had been forked. 1. Including Unicode support at build time is now enabled by default, but it can optionally be disabled. It is not enabled by default at run time (no change). 2. The test program, now called pcre2test, was re-specified and almost completely re-written. Its input is not compatible with input for pcretest. 3. Patterns may start with (*NOTEMPTY) or (*NOTEMPTY_ATSTART) to set the PCRE2_NOTEMPTY or PCRE2_NOTEMPTY_ATSTART options for every subject line that is matched by that pattern. 4. For the benefit of those who use PCRE2 via some other application, that is, not writing the function calls themselves, it is possible to check the PCRE2 version by matching a pattern such as /(?(VERSION>=10)yes|no)/ against a string such as "yesno". 5. There are case-equivalent Unicode characters whose encodings use different numbers of code units in UTF-8. U+023A and U+2C65 are one example. (It is theoretically possible for this to happen in UTF-16 too.) If a backreference to a group containing one of these characters was greedily repeated, and during the match a backtrack occurred, the subject might be backtracked by the wrong number of code units. For example, if /^(\x{23a})\1*(.)/ is matched caselessly (and in UTF-8 mode) against "\x{23a}\x{2c65}\x{2c65}\x{2c65}", group 2 should capture the final character, which is the three bytes E2, B1, and A5 in UTF-8. Incorrect backtracking meant that group 2 captured only the last two bytes. This bug has been fixed; the new code is slower, but it is used only when the strings matched by the repetition are not all the same length. 6. A pattern such as /()a/ was not setting the "first character must be 'a'" information. This applied to any pattern with a group that matched no characters, for example: /(?:(?=.)|(?<!x))a/. 7. When an (*ACCEPT) is triggered inside capturing parentheses, it arranges for those parentheses to be closed with whatever has been captured so far. However, it was failing to mark any other groups between the highest capture so far and the currrent group as "unset". Thus, the ovector for those groups contained whatever was previously there. An example is the pattern /(x)|((*ACCEPT))/ when matched against "abcd". 8. The pcre2_substitute() function has been implemented. 9. If an assertion used as a condition was quantified with a minimum of zero (an odd thing to do, but it happened), SIGSEGV or other misbehaviour could occur. 10. The PCRE2_NO_DOTSTAR_ANCHOR option has been implemented. ****
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