ChangeLog for PCRE ------------------ Version 4.5 01-Dec-03 --------------------- 1. There has been some re-arrangement of the code for the match() function so that it can be compiled in a version that does not call itself recursively. Instead, it keeps those local variables that need separate instances for each "recursion" in a frame on the heap, and gets/frees frames whenever it needs to "recurse". Keeping track of where control must go is done by means of setjmp/longjmp. The whole thing is implemented by a set of macros that hide most of the details from the main code, and operates only if NO_RECURSE is defined while compiling pcre.c. If PCRE is built using the "configure" mechanism, "--disable-stack-for-recursion" turns on this way of operating. To make it easier for callers to provide specially tailored get/free functions for this usage, two new functions, pcre_stack_malloc, and pcre_stack_free, are used. They are always called in strict stacking order, and the size of block requested is always the same. The PCRE_CONFIG_STACKRECURSE info parameter can be used to find out whether PCRE has been compiled to use the stack or the heap for recursion. The -C option of pcretest uses this to show which version is compiled. A new data escape \S, is added to pcretest; it causes the amounts of store obtained and freed by both kinds of malloc/free at match time to be added to the output. 2. Changed the locale test to use "fr_FR" instead of "fr" because that's what's available on my current Linux desktop machine. 3. When matching a UTF-8 string, the test for a valid string at the start has been extended. If start_offset is not zero, PCRE now checks that it points to a byte that is the start of a UTF-8 character. If not, it returns PCRE_ERROR_BADUTF8_OFFSET (-11). Note: the whole string is still checked; this is necessary because there may be backward assertions in the pattern. When matching the same subject several times, it may save resources to use PCRE_NO_UTF8_CHECK on all but the first call if the string is long. 4. The code for checking the validity of UTF-8 strings has been tightened so that it rejects (a) strings containing 0xfe or 0xff bytes and (b) strings containing "overlong sequences". 5. Fixed a bug (appearing twice) that I could not find any way of exploiting! I had written "if ((digitab[*p++] && chtab_digit) == 0)" where the "&&" should have been "&", but it just so happened that all the cases this let through by mistake were picked up later in the function. 6. I had used a variable called "isblank" - this is a C99 function, causing some compilers to warn. To avoid this, I renamed it (as "blankclass"). 7. Cosmetic: (a) only output another newline at the end of pcretest if it is prompting; (b) run "./pcretest /dev/null" at the start of the test script so the version is shown; (c) stop "make test" echoing "./RunTest". 8. Added patches from David Burgess to enable PCRE to run on EBCDIC systems. 9. The prototype for memmove() for systems that don't have it was using size_t, but the inclusion of the header that defines size_t was later. I've moved the #includes for the C headers earlier to avoid this. 10. Added some adjustments to the code to make it easier to compiler on certain special systems: (a) Some "const" qualifiers were missing. (b) Added the macro EXPORT before all exported functions; by default this is defined to be empty. (c) Changed the dftables auxiliary program (that builds chartables.c) so that it reads its output file name as an argument instead of writing to the standard output and assuming this can be redirected. 11. In UTF-8 mode, if a recursive reference (e.g. (?1)) followed a character class containing characters with values greater than 255, PCRE compilation went into a loop. 12. A recursive reference to a subpattern that was within another subpattern that had a minimum quantifier of zero caused PCRE to crash. For example, (x(y(?2))z)? provoked this bug with a subject that got as far as the recursion. If the recursively-called subpattern itself had a zero repeat, that was OK. 13. In pcretest, the buffer for reading a data line was set at 30K, but the buffer into which it was copied (for escape processing) was still set at 1024, so long lines caused crashes. 14. A pattern such as /[ab]{1,3}+/ failed to compile, giving the error "internal error: code overflow...". This applied to any character class that was followed by a possessive quantifier. 15. Modified the Makefile to add libpcre.la as a prerequisite for libpcreposix.la because I was told this is needed for a parallel build to work. 16. If a pattern that contained .* following optional items at the start was studied, the wrong optimizing data was generated, leading to matching errors. For example, studying /[ab]*.*c/ concluded, erroneously, that any matching string must start with a or b or c. The correct conclusion for this pattern is that a match can start with any character. Version 4.4 13-Aug-03 --------------------- 1. In UTF-8 mode, a character class containing characters with values between 127 and 255 was not handled correctly if the compiled pattern was studied. In fixing this, I have also improved the studying algorithm for such classes (slightly). 2. Three internal functions had redundant arguments passed to them. Removal might give a very teeny performance improvement. 3. Documentation bug: the value of the capture_top field in a callout is *one more than* the number of the hightest numbered captured substring. 4. The Makefile linked pcretest and pcregrep with -lpcre, which could result in incorrectly linking with a previously installed version. They now link explicitly with libpcre.la. 5. configure.in no longer needs to recognize Cygwin specially. 6. A problem in pcre.in for Windows platforms is fixed. 7. If a pattern was successfully studied, and the -d (or /D) flag was given to pcretest, it used to include the size of the study block as part of its output. Unfortunately, the structure contains a field that has a different size on different hardware architectures. This meant that the tests that showed this size failed. As the block is currently always of a fixed size, this information isn't actually particularly useful in pcretest output, so I have just removed it. 8. Three pre-processor statements accidentally did not start in column 1. Sadly, there are *still* compilers around that complain, even though standard C has not required this for well over a decade. Sigh. 9. In pcretest, the code for checking callouts passed small integers in the callout_data field, which is a void * field. However, some picky compilers complained about the casts involved for this on 64-bit systems. Now pcretest passes the address of the small integer instead, which should get rid of the warnings. 10. By default, when in UTF-8 mode, PCRE now checks for valid UTF-8 strings at both compile and run time, and gives an error if an invalid UTF-8 sequence is found. There is a option for disabling this check in cases where the string is known to be correct and/or the maximum performance is wanted. 11. In response to a bug report, I changed one line in Makefile.in from -Wl,--out-implib,.libs/lib@WIN_PREFIX@pcreposix.dll.a \ to -Wl,--out-implib,.libs/@WIN_PREFIX@libpcreposix.dll.a \ to look similar to other lines, but I have no way of telling whether this is the right thing to do, as I do not use Windows. No doubt I'll get told if it's wrong... Version 4.3 21-May-03 --------------------- 1. Two instances of @WIN_PREFIX@ omitted from the Windows targets in the Makefile. 2. Some refactoring to improve the quality of the code: (i) The utf8_table... variables are now declared "const". (ii) The code for \cx, which used the "case flipping" table to upper case lower case letters, now just substracts 32. This is ASCII-specific, but the whole concept of \cx is ASCII-specific, so it seems reasonable. (iii) PCRE was using its character types table to recognize decimal and hexadecimal digits in the pattern. This is silly, because it handles only 0-9, a-f, and A-F, but the character types table is locale- specific, which means strange things might happen. A private table is now used for this - though it costs 256 bytes, a table is much faster than multiple explicit tests. Of course, the standard character types table is still used for matching digits in subject strings against \d. (iv) Strictly, the identifier ESC_t is reserved by POSIX (all identifiers ending in _t are). So I've renamed it as ESC_tee. 3. The first argument for regexec() in the POSIX wrapper should have been defined as "const". 4. Changed pcretest to use malloc() for its buffers so that they can be Electric Fenced for debugging. 5. There were several places in the code where, in UTF-8 mode, PCRE would try to read one or more bytes before the start of the subject string. Often this had no effect on PCRE's behaviour, but in some circumstances it could provoke a segmentation fault. 6. A lookbehind at the start of a pattern in UTF-8 mode could also cause PCRE to try to read one or more bytes before the start of the subject string. 7. A lookbehind in a pattern matched in non-UTF-8 mode on a PCRE compiled with UTF-8 support could misbehave in various ways if the subject string contained bytes with the 0x80 bit set and the 0x40 bit unset in a lookbehind area. (PCRE was not checking for the UTF-8 mode flag, and trying to move back over UTF-8 characters.) Version 4.2 14-Apr-03 --------------------- 1. Typo "#if SUPPORT_UTF8" instead of "#ifdef SUPPORT_UTF8" fixed. 2. Changes to the building process, supplied by Ronald Landheer-Cieslak [ON_WINDOWS]: new variable, "#" on non-Windows platforms [NOT_ON_WINDOWS]: new variable, "#" on Windows platforms [WIN_PREFIX]: new variable, "cyg" for Cygwin * Makefile.in: use autoconf substitution for OBJEXT, EXEEXT, BUILD_OBJEXT and BUILD_EXEEXT Note: automatic setting of the BUILD variables is not yet working set CPPFLAGS and BUILD_CPPFLAGS (but don't use yet) - should be used at compile-time but not at link-time [LINK]: use for linking executables only make different versions for Windows and non-Windows [LINKLIB]: new variable, copy of UNIX-style LINK, used for linking libraries [LINK_FOR_BUILD]: new variable [OBJEXT]: use throughout [EXEEXT]: use throughout : new target : new target : use native compiler : use native linker : handle Windows platform correctly : ditto : ditto copy DLL to top builddir before testing As part of these changes, -no-undefined was removed again. This was reported to give trouble on HP-UX 11.0, so getting rid of it seems like a good idea in any case. 3. Some tidies to get rid of compiler warnings: . In the match_data structure, match_limit was an unsigned long int, whereas match_call_count was an int. I've made them both unsigned long ints. . In pcretest the fact that a const uschar * doesn't automatically cast to a void * provoked a warning. . Turning on some more compiler warnings threw up some "shadow" variables and a few more missing casts. 4. If PCRE was complied with UTF-8 support, but called without the PCRE_UTF8 option, a class that contained a single character with a value between 128 and 255 (e.g. /[\xFF]/) caused PCRE to crash. 5. If PCRE was compiled with UTF-8 support, but called without the PCRE_UTF8 option, a class that contained several characters, but with at least one whose value was between 128 and 255 caused PCRE to crash. Version 4.1 12-Mar-03 --------------------- 1. Compiling with gcc -pedantic found a couple of places where casts were needed, and a string in dftables.c that was longer than standard compilers are required to support. 2. Compiling with Sun's compiler found a few more places where the code could be tidied up in order to avoid warnings. 3. The variables for cross-compiling were called HOST_CC and HOST_CFLAGS; the first of these names is deprecated in the latest Autoconf in favour of the name CC_FOR_BUILD, because "host" is typically used to mean the system on which the compiled code will be run. I can't find a reference for HOST_CFLAGS, but by analogy I have changed it to CFLAGS_FOR_BUILD. 4. Added -no-undefined to the linking command in the Makefile, because this is apparently helpful for Windows. To make it work, also added "-L. -lpcre" to the linking step for the pcreposix library. 5. PCRE was failing to diagnose the case of two named groups with the same name. 6. A problem with one of PCRE's optimizations was discovered. PCRE remembers a literal character that is needed in the subject for a match, and scans along to ensure that it is present before embarking on the full matching process. This saves time in cases of nested unlimited repeats that are never going to match. Problem: the scan can take a lot of time if the subject is very long (e.g. megabytes), thus penalizing straightforward matches. It is now done only if the amount of subject to be scanned is less than 1000 bytes. 7. A lesser problem with the same optimization is that it was recording the first character of an anchored pattern as "needed", thus provoking a search right along the subject, even when the first match of the pattern was going to fail. The "needed" character is now not set for anchored patterns, unless it follows something in the pattern that is of non-fixed length. Thus, it still fulfils its original purpose of finding quick non-matches in cases of nested unlimited repeats, but isn't used for simple anchored patterns such as /^abc/. Version 4.0 17-Feb-03 --------------------- 1. If a comment in an extended regex that started immediately after a meta-item extended to the end of string, PCRE compiled incorrect data. This could lead to all kinds of weird effects. Example: /#/ was bad; /()#/ was bad; /a#/ was not. 2. Moved to autoconf 2.53 and libtool 1.4.2. 3. Perl 5.8 no longer needs "use utf8" for doing UTF-8 things. Consequently, the special perltest8 script is no longer needed - all the tests can be run from a single perltest script. 4. From 5.004, Perl has not included the VT character (0x0b) in the set defined by \s. It has now been removed in PCRE. This means it isn't recognized as whitespace in /x regexes too, which is the same as Perl. Note that the POSIX class [:space:] *does* include VT, thereby creating a mess. 5. Added the class [:blank:] (a GNU extension from Perl 5.8) to match only space and tab. 6. Perl 5.005 was a long time ago. It's time to amalgamate the tests that use its new features into the main test script, reducing the number of scripts. 7. Perl 5.8 has changed the meaning of patterns like /a(?i)b/. Earlier versions were backward compatible, and made the (?i) apply to the whole pattern, as if /i were given. Now it behaves more logically, and applies the option setting only to what follows. PCRE has been changed to follow suit. However, if it finds options settings right at the start of the pattern, it extracts them into the global options, as before. Thus, they show up in the info data. 8. Added support for the \Q...\E escape sequence. Characters in between are treated as literals. This is slightly different from Perl in that $ and @ are also handled as literals inside the quotes. In Perl, they will cause variable interpolation. Note the following examples: Pattern PCRE matches Perl matches \Qabc$xyz\E abc$xyz abc followed by the contents of $xyz \Qabc\$xyz\E abc\$xyz abc\$xyz \Qabc\E\$\Qxyz\E abc$xyz abc$xyz For compatibility with Perl, \Q...\E sequences are recognized inside character classes as well as outside them. 9. Re-organized 3 code statements in pcretest to avoid "overflow in floating-point constant arithmetic" warnings from a Microsoft compiler. Added a (size_t) cast to one statement in pcretest and one in pcreposix to avoid signed/unsigned warnings. 10. SunOS4 doesn't have strtoul(). This was used only for unpicking the -o option for pcretest, so I've replaced it by a simple function that does just that job. 11. pcregrep was ending with code 0 instead of 2 for the commands "pcregrep" or "pcregrep -". 12. Added "possessive quantifiers" ?+, *+, ++, and {,}+ which come from Sun's Java package. This provides some syntactic sugar for simple cases of what my documentation calls "once-only subpatterns". A pattern such as x*+ is the same as (?>x*). In other words, if what is inside (?>...) is just a single repeated item, you can use this simplified notation. Note that only makes sense with greedy quantifiers. Consequently, the use of the possessive quantifier forces greediness, whatever the setting of the PCRE_UNGREEDY option. 13. A change of greediness default within a pattern was not taking effect at the current level for patterns like /(b+(?U)a+)/. It did apply to parenthesized subpatterns that followed. Patterns like /b+(?U)a+/ worked because the option was abstracted outside. 14. PCRE now supports the \G assertion. It is true when the current matching position is at the start point of the match. This differs from \A when the starting offset is non-zero. Used with the /g option of pcretest (or similar code), it works in the same way as it does for Perl's /g option. If all alternatives of a regex begin with \G, the expression is anchored to the start match position, and the "anchored" flag is set in the compiled expression. 15. Some bugs concerning the handling of certain option changes within patterns have been fixed. These applied to options other than (?ims). For example, "a(?x: b c )d" did not match "XabcdY" but did match "Xa b c dY". It should have been the other way round. Some of this was related to change 7 above. 16. PCRE now gives errors for /[.x.]/ and /[=x=]/ as unsupported POSIX features, as Perl does. Previously, PCRE gave the warnings only for /[[.x.]]/ and /[[=x=]]/. PCRE now also gives an error for /[:name:]/ because it supports POSIX classes only within a class (e.g. /[[:alpha:]]/). 17. Added support for Perl's \C escape. This matches one byte, even in UTF8 mode. Unlike ".", it always matches newline, whatever the setting of PCRE_DOTALL. However, PCRE does not permit \C to appear in lookbehind assertions. Perl allows it, but it doesn't (in general) work because it can't calculate the length of the lookbehind. At least, that's the case for Perl 5.8.0 - I've been told they are going to document that it doesn't work in future. 18. Added an error diagnosis for escapes that PCRE does not support: these are \L, \l, \N, \P, \p, \U, \u, and \X. 19. Although correctly diagnosing a missing ']' in a character class, PCRE was reading past the end of the pattern in cases such as /[abcd/. 20. PCRE was getting more memory than necessary for patterns with classes that contained both POSIX named classes and other characters, e.g. /[[:space:]abc/. 21. Added some code, conditional on #ifdef VPCOMPAT, to make life easier for compiling PCRE for use with Virtual Pascal. 22. Small fix to the Makefile to make it work properly if the build is done outside the source tree. 23. Added a new extension: a condition to go with recursion. If a conditional subpattern starts with (?(R) the "true" branch is used if recursion has happened, whereas the "false" branch is used only at the top level. 24. When there was a very long string of literal characters (over 255 bytes without UTF support, over 250 bytes with UTF support), the computation of how much memory was required could be incorrect, leading to segfaults or other strange effects. 25. PCRE was incorrectly assuming anchoring (either to start of subject or to start of line for a non-DOTALL pattern) when a pattern started with (.*) and there was a subsequent back reference to those brackets. This meant that, for example, /(.*)\d+\1/ failed to match "abc123bc". Unfortunately, it isn't possible to check for precisely this case. All we can do is abandon the optimization if .* occurs inside capturing brackets when there are any back references whatsoever. (See below for a better fix that came later.) 26. The handling of the optimization for finding the first character of a non-anchored pattern, and for finding a character that is required later in the match were failing in some cases. This didn't break the matching; it just failed to optimize when it could. The way this is done has been re-implemented. 27. Fixed typo in error message for invalid (?R item (it said "(?p"). 28. Added a new feature that provides some of the functionality that Perl provides with (?{...}). The facility is termed a "callout". The way it is done in PCRE is for the caller to provide an optional function, by setting pcre_callout to its entry point. Like pcre_malloc and pcre_free, this is a global variable. By default it is unset, which disables all calling out. To get the function called, the regex must include (?C) at appropriate points. This is, in fact, equivalent to (?C0), and any number <= 255 may be given with (?C). This provides a means of identifying different callout points. When PCRE reaches such a point in the regex, if pcre_callout has been set, the external function is called. It is provided with data in a structure called pcre_callout_block, which is defined in pcre.h. If the function returns 0, matching continues; if it returns a non-zero value, the match at the current point fails. However, backtracking will occur if possible. [This was changed later and other features added - see item 49 below.] 29. pcretest is upgraded to test the callout functionality. It provides a callout function that displays information. By default, it shows the start of the match and the current position in the text. There are some new data escapes to vary what happens: \C+ in addition, show current contents of captured substrings \C- do not supply a callout function \C!n return 1 when callout number n is reached \C!n!m return 1 when callout number n is reached for the mth time 30. If pcregrep was called with the -l option and just a single file name, it output "" if a match was found, instead of the file name. 31. Improve the efficiency of the POSIX API to PCRE. If the number of capturing slots is less than POSIX_MALLOC_THRESHOLD, use a block on the stack to pass to pcre_exec(). This saves a malloc/free per call. The default value of POSIX_MALLOC_THRESHOLD is 10; it can be changed by --with-posix-malloc-threshold when configuring. 32. The default maximum size of a compiled pattern is 64K. There have been a few cases of people hitting this limit. The code now uses macros to handle the storing of links as offsets within the compiled pattern. It defaults to 2-byte links, but this can be changed to 3 or 4 bytes by --with-link-size when configuring. Tests 2 and 5 work only with 2-byte links because they output debugging information about compiled patterns. 33. Internal code re-arrangements: (a) Moved the debugging function for printing out a compiled regex into its own source file (printint.c) and used #include to pull it into pcretest.c and, when DEBUG is defined, into pcre.c, instead of having two separate copies. (b) Defined the list of op-code names for debugging as a macro in internal.h so that it is next to the definition of the opcodes. (c) Defined a table of op-code lengths for simpler skipping along compiled code. This is again a macro in internal.h so that it is next to the definition of the opcodes. 34. Added support for recursive calls to individual subpatterns, along the lines of Robin Houston's patch (but implemented somewhat differently). 35. Further mods to the Makefile to help Win32. Also, added code to pcregrep to allow it to read and process whole directories in Win32. This code was contributed by Lionel Fourquaux; it has not been tested by me. 36. Added support for named subpatterns. The Python syntax (?P...) is used to name a group. Names consist of alphanumerics and underscores, and must be unique. Back references use the syntax (?P=name) and recursive calls use (?P>name) which is a PCRE extension to the Python extension. Groups still have numbers. The function pcre_fullinfo() can be used after compilation to extract a name/number map. There are three relevant calls: PCRE_INFO_NAMEENTRYSIZE yields the size of each entry in the map PCRE_INFO_NAMECOUNT yields the number of entries PCRE_INFO_NAMETABLE yields a pointer to the map. The map is a vector of fixed-size entries. The size of each entry depends on the length of the longest name used. The first two bytes of each entry are the group number, most significant byte first. There follows the corresponding name, zero terminated. The names are in alphabetical order. 37. Make the maximum literal string in the compiled code 250 for the non-UTF-8 case instead of 255. Making it the same both with and without UTF-8 support means that the same test output works with both. 38. There was a case of malloc(0) in the POSIX testing code in pcretest. Avoid calling malloc() with a zero argument. 39. Change 25 above had to resort to a heavy-handed test for the .* anchoring optimization. I've improved things by keeping a bitmap of backreferences with numbers 1-31 so that if .* occurs inside capturing brackets that are not in fact referenced, the optimization can be applied. It is unlikely that a relevant occurrence of .* (i.e. one which might indicate anchoring or forcing the match to follow \n) will appear inside brackets with a number greater than 31, but if it does, any back reference > 31 suppresses the optimization. 40. Added a new compile-time option PCRE_NO_AUTO_CAPTURE. This has the effect of disabling numbered capturing parentheses. Any opening parenthesis that is not followed by ? behaves as if it were followed by ?: but named parentheses can still be used for capturing (and they will acquire numbers in the usual way). 41. Redesigned the return codes from the match() function into yes/no/error so that errors can be passed back from deep inside the nested calls. A malloc failure while inside a recursive subpattern call now causes the PCRE_ERROR_NOMEMORY return instead of quietly going wrong. 42. It is now possible to set a limit on the number of times the match() function is called in a call to pcre_exec(). This facility makes it possible to limit the amount of recursion and backtracking, though not in a directly obvious way, because the match() function is used in a number of different circumstances. The count starts from zero for each position in the subject string (for non-anchored patterns). The default limit is, for compatibility, a large number, namely 10 000 000. You can change this in two ways: (a) When configuring PCRE before making, you can use --with-match-limit=n to set a default value for the compiled library. (b) For each call to pcre_exec(), you can pass a pcre_extra block in which a different value is set. See 45 below. If the limit is exceeded, pcre_exec() returns PCRE_ERROR_MATCHLIMIT. 43. Added a new function pcre_config(int, void *) to enable run-time extraction of things that can be changed at compile time. The first argument specifies what is wanted and the second points to where the information is to be placed. The current list of available information is: PCRE_CONFIG_UTF8 The output is an integer that is set to one if UTF-8 support is available; otherwise it is set to zero. PCRE_CONFIG_NEWLINE The output is an integer that it set to the value of the code that is used for newline. It is either LF (10) or CR (13). PCRE_CONFIG_LINK_SIZE The output is an integer that contains the number of bytes used for internal linkage in compiled expressions. The value is 2, 3, or 4. See item 32 above. PCRE_CONFIG_POSIX_MALLOC_THRESHOLD The output is an integer that contains the threshold above which the POSIX interface uses malloc() for output vectors. See item 31 above. PCRE_CONFIG_MATCH_LIMIT The output is an unsigned integer that contains the default limit of the number of match() calls in a pcre_exec() execution. See 42 above. 44. pcretest has been upgraded by the addition of the -C option. This causes it to extract all the available output from the new pcre_config() function, and to output it. The program then exits immediately. 45. A need has arisen to pass over additional data with calls to pcre_exec() in order to support additional features. One way would have been to define pcre_exec2() (for example) with extra arguments, but this would not have been extensible, and would also have required all calls to the original function to be mapped to the new one. Instead, I have chosen to extend the mechanism that is used for passing in "extra" data from pcre_study(). The pcre_extra structure is now exposed and defined in pcre.h. It currently contains the following fields: flags a bitmap indicating which of the following fields are set study_data opaque data from pcre_study() match_limit a way of specifying a limit on match() calls for a specific call to pcre_exec() callout_data data for callouts (see 49 below) The flag bits are also defined in pcre.h, and are PCRE_EXTRA_STUDY_DATA PCRE_EXTRA_MATCH_LIMIT PCRE_EXTRA_CALLOUT_DATA The pcre_study() function now returns one of these new pcre_extra blocks, with the actual study data pointed to by the study_data field, and the PCRE_EXTRA_STUDY_DATA flag set. This can be passed directly to pcre_exec() as before. That is, this change is entirely upwards-compatible and requires no change to existing code. If you want to pass in additional data to pcre_exec(), you can either place it in a pcre_extra block provided by pcre_study(), or create your own pcre_extra block. 46. pcretest has been extended to test the PCRE_EXTRA_MATCH_LIMIT feature. If a data string contains the escape sequence \M, pcretest calls pcre_exec() several times with different match limits, until it finds the minimum value needed for pcre_exec() to complete. The value is then output. This can be instructive; for most simple matches the number is quite small, but for pathological cases it gets very large very quickly. 47. There's a new option for pcre_fullinfo() called PCRE_INFO_STUDYSIZE. It returns the size of the data block pointed to by the study_data field in a pcre_extra block, that is, the value that was passed as the argument to pcre_malloc() when PCRE was getting memory in which to place the information created by pcre_study(). The fourth argument should point to a size_t variable. pcretest has been extended so that this information is shown after a successful pcre_study() call when information about the compiled regex is being displayed. 48. Cosmetic change to Makefile: there's no need to have / after $(DESTDIR) because what follows is always an absolute path. (Later: it turns out that this is more than cosmetic for MinGW, because it doesn't like empty path components.) 49. Some changes have been made to the callout feature (see 28 above): (i) A callout function now has three choices for what it returns: 0 => success, carry on matching > 0 => failure at this point, but backtrack if possible < 0 => serious error, return this value from pcre_exec() Negative values should normally be chosen from the set of PCRE_ERROR_xxx values. In particular, returning PCRE_ERROR_NOMATCH forces a standard "match failed" error. The error number PCRE_ERROR_CALLOUT is reserved for use by callout functions. It will never be used by PCRE itself. (ii) The pcre_extra structure (see 45 above) has a void * field called callout_data, with corresponding flag bit PCRE_EXTRA_CALLOUT_DATA. The pcre_callout_block structure has a field of the same name. The contents of the field passed in the pcre_extra structure are passed to the callout function in the corresponding field in the callout block. This makes it easier to use the same callout-containing regex from multiple threads. For testing, the pcretest program has a new data escape \C*n pass the number n (may be negative) as callout_data If the callout function in pcretest receives a non-zero value as callout_data, it returns that value. 50. Makefile wasn't handling CFLAGS properly when compiling dftables. Also, there were some redundant $(CFLAGS) in commands that are now specified as $(LINK), which already includes $(CFLAGS). 51. Extensions to UTF-8 support are listed below. These all apply when (a) PCRE has been compiled with UTF-8 support *and* pcre_compile() has been compiled with the PCRE_UTF8 flag. Patterns that are compiled without that flag assume one-byte characters throughout. Note that case-insensitive matching applies only to characters whose values are less than 256. PCRE doesn't support the notion of cases for higher-valued characters. (i) A character class whose characters are all within 0-255 is handled as a bit map, and the map is inverted for negative classes. Previously, a character > 255 always failed to match such a class; however it should match if the class was a negative one (e.g. [^ab]). This has been fixed. (ii) A negated character class with a single character < 255 is coded as "not this character" (OP_NOT). This wasn't working properly when the test character was multibyte, either singly or repeated. (iii) Repeats of multibyte characters are now handled correctly in UTF-8 mode, for example: \x{100}{2,3}. (iv) The character escapes \b, \B, \d, \D, \s, \S, \w, and \W (either singly or repeated) now correctly test multibyte characters. However, PCRE doesn't recognize any characters with values greater than 255 as digits, spaces, or word characters. Such characters always match \D, \S, and \W, and never match \d, \s, or \w. (v) Classes may now contain characters and character ranges with values greater than 255. For example: [ab\x{100}-\x{400}]. (vi) pcregrep now has a --utf-8 option (synonym -u) which makes it call PCRE in UTF-8 mode. 52. The info request value PCRE_INFO_FIRSTCHAR has been renamed PCRE_INFO_FIRSTBYTE because it is a byte value. However, the old name is retained for backwards compatibility. (Note that LASTLITERAL is also a byte value.) 53. The single man page has become too large. I have therefore split it up into a number of separate man pages. These also give rise to individual HTML pages; these are now put in a separate directory, and there is an index.html page that lists them all. Some hyperlinking between the pages has been installed. 54. Added convenience functions for handling named capturing parentheses. 55. Unknown escapes inside character classes (e.g. [\M]) and escapes that aren't interpreted therein (e.g. [\C]) are literals in Perl. This is now also true in PCRE, except when the PCRE_EXTENDED option is set, in which case they are faulted. 56. Introduced HOST_CC and HOST_CFLAGS which can be set in the environment when calling configure. These values are used when compiling the dftables.c program which is run to generate the source of the default character tables. They default to the values of CC and CFLAGS. If you are cross-compiling PCRE, you will need to set these values. 57. Updated the building process for Windows DLL, as provided by Fred Cox. Version 3.9 02-Jan-02 --------------------- 1. A bit of extraneous text had somehow crept into the pcregrep documentation. 2. If --disable-static was given, the building process failed when trying to build pcretest and pcregrep. (For some reason it was using libtool to compile them, which is not right, as they aren't part of the library.) Version 3.8 18-Dec-01 --------------------- 1. The experimental UTF-8 code was completely screwed up. It was packing the bytes in the wrong order. How dumb can you get? Version 3.7 29-Oct-01 --------------------- 1. In updating pcretest to check change 1 of version 3.6, I screwed up. This caused pcretest, when used on the test data, to segfault. Unfortunately, this didn't happen under Solaris 8, where I normally test things. 2. The Makefile had to be changed to make it work on BSD systems, where 'make' doesn't seem to recognize that ./xxx and xxx are the same file. (This entry isn't in ChangeLog distributed with 3.7 because I forgot when I hastily made this fix an hour or so after the initial 3.7 release.) Version 3.6 23-Oct-01 --------------------- 1. Crashed with /(sens|respons)e and \1ibility/ and "sense and sensibility" if offsets passed as NULL with zero offset count. 2. The config.guess and config.sub files had not been updated when I moved to the latest autoconf. Version 3.5 15-Aug-01 --------------------- 1. Added some missing #if !defined NOPOSIX conditionals in pcretest.c that had been forgotten. 2. By using declared but undefined structures, we can avoid using "void" definitions in pcre.h while keeping the internal definitions of the structures private. 3. The distribution is now built using autoconf 2.50 and libtool 1.4. From a user point of view, this means that both static and shared libraries are built by default, but this can be individually controlled. More of the work of handling this static/shared cases is now inside libtool instead of PCRE's make file. 4. The pcretest utility is now installed along with pcregrep because it is useful for users (to test regexs) and by doing this, it automatically gets relinked by libtool. The documentation has been turned into a man page, so there are now .1, .txt, and .html versions in /doc. 5. Upgrades to pcregrep: (i) Added long-form option names like gnu grep. (ii) Added --help to list all options with an explanatory phrase. (iii) Added -r, --recursive to recurse into sub-directories. (iv) Added -f, --file to read patterns from a file. 6. pcre_exec() was referring to its "code" argument before testing that argument for NULL (and giving an error if it was NULL). 7. Upgraded Makefile.in to allow for compiling in a different directory from the source directory. 8. Tiny buglet in pcretest: when pcre_fullinfo() was called to retrieve the options bits, the pointer it was passed was to an int instead of to an unsigned long int. This mattered only on 64-bit systems. 9. Fixed typo (3.4/1) in pcre.h again. Sigh. I had changed pcre.h (which is generated) instead of pcre.in, which it its source. Also made the same change in several of the .c files. 10. A new release of gcc defines printf() as a macro, which broke pcretest because it had an ifdef in the middle of a string argument for printf(). Fixed by using separate calls to printf(). 11. Added --enable-newline-is-cr and --enable-newline-is-lf to the configure script, to force use of CR or LF instead of \n in the source. On non-Unix systems, the value can be set in config.h. 12. The limit of 200 on non-capturing parentheses is a _nesting_ limit, not an absolute limit. Changed the text of the error message to make this clear, and likewise updated the man page. 13. The limit of 99 on the number of capturing subpatterns has been removed. The new limit is 65535, which I hope will not be a "real" limit. Version 3.4 22-Aug-00 --------------------- 1. Fixed typo in pcre.h: unsigned const char * changed to const unsigned char *. 2. Diagnose condition (?(0) as an error instead of crashing on matching. Version 3.3 01-Aug-00 --------------------- 1. If an octal character was given, but the value was greater than \377, it was not getting masked to the least significant bits, as documented. This could lead to crashes in some systems. 2. Perl 5.6 (if not earlier versions) accepts classes like [a-\d] and treats the hyphen as a literal. PCRE used to give an error; it now behaves like Perl. 3. Added the functions pcre_free_substring() and pcre_free_substring_list(). These just pass their arguments on to (pcre_free)(), but they are provided because some uses of PCRE bind it to non-C systems that can call its functions, but cannot call free() or pcre_free() directly. 4. Add "make test" as a synonym for "make check". Corrected some comments in the Makefile. 5. Add $(DESTDIR)/ in front of all the paths in the "install" target in the Makefile. 6. Changed the name of pgrep to pcregrep, because Solaris has introduced a command called pgrep for grepping around the active processes. 7. Added the beginnings of support for UTF-8 character strings. 8. Arranged for the Makefile to pass over the settings of CC, CFLAGS, and RANLIB to ./ltconfig so that they are used by libtool. I think these are all the relevant ones. (AR is not passed because ./ltconfig does its own figuring out for the ar command.) Version 3.2 12-May-00 --------------------- This is purely a bug fixing release. 1. If the pattern /((Z)+|A)*/ was matched agained ZABCDEFG it matched Z instead of ZA. This was just one example of several cases that could provoke this bug, which was introduced by change 9 of version 2.00. The code for breaking infinite loops after an iteration that matches an empty string was't working correctly. 2. The pcretest program was not imitating Perl correctly for the pattern /a*/g when matched against abbab (for example). After matching an empty string, it wasn't forcing anchoring when setting PCRE_NOTEMPTY for the next attempt; this caused it to match further down the string than it should. 3. The code contained an inclusion of sys/types.h. It isn't clear why this was there because it doesn't seem to be needed, and it causes trouble on some systems, as it is not a Standard C header. It has been removed. 4. Made 4 silly changes to the source to avoid stupid compiler warnings that were reported on the Macintosh. The changes were from while ((c = *(++ptr)) != 0 && c != '\n'); to while ((c = *(++ptr)) != 0 && c != '\n') ; Totally extraordinary, but if that's what it takes... 5. PCRE is being used in one environment where neither memmove() nor bcopy() is available. Added HAVE_BCOPY and an autoconf test for it; if neither HAVE_MEMMOVE nor HAVE_BCOPY is set, use a built-in emulation function which assumes the way PCRE uses memmove() (always moving upwards). 6. PCRE is being used in one environment where strchr() is not available. There was only one use in pcre.c, and writing it out to avoid strchr() probably gives faster code anyway. Version 3.1 09-Feb-00 --------------------- The only change in this release is the fixing of some bugs in Makefile.in for the "install" target: (1) It was failing to install pcreposix.h. (2) It was overwriting the pcre.3 man page with the pcreposix.3 man page. Version 3.0 01-Feb-00 --------------------- 1. Add support for the /+ modifier to perltest (to output $` like it does in pcretest). 2. Add support for the /g modifier to perltest. 3. Fix pcretest so that it behaves even more like Perl for /g when the pattern matches null strings. 4. Fix perltest so that it doesn't do unwanted things when fed an empty pattern. Perl treats empty patterns specially - it reuses the most recent pattern, which is not what we want. Replace // by /(?#)/ in order to avoid this effect. 5. The POSIX interface was broken in that it was just handing over the POSIX captured string vector to pcre_exec(), but (since release 2.00) PCRE has required a bigger vector, with some working space on the end. This means that the POSIX wrapper now has to get and free some memory, and copy the results. 6. Added some simple autoconf support, placing the test data and the documentation in separate directories, re-organizing some of the information files, and making it build pcre-config (a GNU standard). Also added libtool support for building PCRE as a shared library, which is now the default. 7. Got rid of the leading zero in the definition of PCRE_MINOR because 08 and 09 are not valid octal constants. Single digits will be used for minor values less than 10. 8. Defined REG_EXTENDED and REG_NOSUB as zero in the POSIX header, so that existing programs that set these in the POSIX interface can use PCRE without modification. 9. Added a new function, pcre_fullinfo() with an extensible interface. It can return all that pcre_info() returns, plus additional data. The pcre_info() function is retained for compatibility, but is considered to be obsolete. 10. Added experimental recursion feature (?R) to handle one common case that Perl 5.6 will be able to do with (?p{...}). 11. Added support for POSIX character classes like [:alpha:], which Perl is adopting. Version 2.08 31-Aug-99 ---------------------- 1. When startoffset was not zero and the pattern began with ".*", PCRE was not trying to match at the startoffset position, but instead was moving forward to the next newline as if a previous match had failed. 2. pcretest was not making use of PCRE_NOTEMPTY when repeating for /g and /G, and could get into a loop if a null string was matched other than at the start of the subject. 3. Added definitions of PCRE_MAJOR and PCRE_MINOR to pcre.h so the version can be distinguished at compile time, and for completeness also added PCRE_DATE. 5. Added Paul Sokolovsky's minor changes to make it easy to compile a Win32 DLL in GnuWin32 environments. Version 2.07 29-Jul-99 ---------------------- 1. The documentation is now supplied in plain text form and HTML as well as in the form of man page sources. 2. C++ compilers don't like assigning (void *) values to other pointer types. In particular this affects malloc(). Although there is no problem in Standard C, I've put in casts to keep C++ compilers happy. 3. Typo on pcretest.c; a cast of (unsigned char *) in the POSIX regexec() call should be (const char *). 4. If NOPOSIX is defined, pcretest.c compiles without POSIX support. This may be useful for non-Unix systems who don't want to bother with the POSIX stuff. However, I haven't made this a standard facility. The documentation doesn't mention it, and the Makefile doesn't support it. 5. The Makefile now contains an "install" target, with editable destinations at the top of the file. The pcretest program is not installed. 6. pgrep -V now gives the PCRE version number and date. 7. Fixed bug: a zero repetition after a literal string (e.g. /abcde{0}/) was causing the entire string to be ignored, instead of just the last character. 8. If a pattern like /"([^\\"]+|\\.)*"/ is applied in the normal way to a non-matching string, it can take a very, very long time, even for strings of quite modest length, because of the nested recursion. PCRE now does better in some of these cases. It does this by remembering the last required literal character in the pattern, and pre-searching the subject to ensure it is present before running the real match. In other words, it applies a heuristic to detect some types of certain failure quickly, and in the above example, if presented with a string that has no trailing " it gives "no match" very quickly. 9. A new runtime option PCRE_NOTEMPTY causes null string matches to be ignored; other alternatives are tried instead. Version 2.06 09-Jun-99 ---------------------- 1. Change pcretest's output for amount of store used to show just the code space, because the remainder (the data block) varies in size between 32-bit and 64-bit systems. 2. Added an extra argument to pcre_exec() to supply an offset in the subject to start matching at. This allows lookbehinds to work when searching for multiple occurrences in a string. 3. Added additional options to pcretest for testing multiple occurrences: /+ outputs the rest of the string that follows a match /g loops for multiple occurrences, using the new startoffset argument /G loops for multiple occurrences by passing an incremented pointer 4. PCRE wasn't doing the "first character" optimization for patterns starting with \b or \B, though it was doing it for other lookbehind assertions. That is, it wasn't noticing that a match for a pattern such as /\bxyz/ has to start with the letter 'x'. On long subject strings, this gives a significant speed-up. Version 2.05 21-Apr-99 ---------------------- 1. Changed the type of magic_number from int to long int so that it works properly on 16-bit systems. 2. Fixed a bug which caused patterns starting with .* not to work correctly when the subject string contained newline characters. PCRE was assuming anchoring for such patterns in all cases, which is not correct because .* will not pass a newline unless PCRE_DOTALL is set. It now assumes anchoring only if DOTALL is set at top level; otherwise it knows that patterns starting with .* must be retried after every newline in the subject. Version 2.04 18-Feb-99 ---------------------- 1. For parenthesized subpatterns with repeats whose minimum was zero, the computation of the store needed to hold the pattern was incorrect (too large). If such patterns were nested a few deep, this could multiply and become a real problem. 2. Added /M option to pcretest to show the memory requirement of a specific pattern. Made -m a synonym of -s (which does this globally) for compatibility. 3. Subpatterns of the form (regex){n,m} (i.e. limited maximum) were being compiled in such a way that the backtracking after subsequent failure was pessimal. Something like (a){0,3} was compiled as (a)?(a)?(a)? instead of ((a)((a)(a)?)?)? with disastrous performance if the maximum was of any size. Version 2.03 02-Feb-99 ---------------------- 1. Fixed typo and small mistake in man page. 2. Added 4th condition (GPL supersedes if conflict) and created separate LICENCE file containing the conditions. 3. Updated pcretest so that patterns such as /abc\/def/ work like they do in Perl, that is the internal \ allows the delimiter to be included in the pattern. Locked out the use of \ as a delimiter. If \ immediately follows the final delimiter, add \ to the end of the pattern (to test the error). 4. Added the convenience functions for extracting substrings after a successful match. Updated pcretest to make it able to test these functions. Version 2.02 14-Jan-99 ---------------------- 1. Initialized the working variables associated with each extraction so that their saving and restoring doesn't refer to uninitialized store. 2. Put dummy code into study.c in order to trick the optimizer of the IBM C compiler for OS/2 into generating correct code. Apparently IBM isn't going to fix the problem. 3. Pcretest: the timing code wasn't using LOOPREPEAT for timing execution calls, and wasn't printing the correct value for compiling calls. Increased the default value of LOOPREPEAT, and the number of significant figures in the times. 4. Changed "/bin/rm" in the Makefile to "-rm" so it works on Windows NT. 5. Renamed "deftables" as "dftables" to get it down to 8 characters, to avoid a building problem on Windows NT with a FAT file system. Version 2.01 21-Oct-98 ---------------------- 1. Changed the API for pcre_compile() to allow for the provision of a pointer to character tables built by pcre_maketables() in the current locale. If NULL is passed, the default tables are used. Version 2.00 24-Sep-98 ---------------------- 1. Since the (>?) facility is in Perl 5.005, don't require PCRE_EXTRA to enable it any more. 2. Allow quantification of (?>) groups, and make it work correctly. 3. The first character computation wasn't working for (?>) groups. 4. Correct the implementation of \Z (it is permitted to match on the \n at the end of the subject) and add 5.005's \z, which really does match only at the very end of the subject. 5. Remove the \X "cut" facility; Perl doesn't have it, and (?> is neater. 6. Remove the ability to specify CASELESS, MULTILINE, DOTALL, and DOLLAR_END_ONLY at runtime, to make it possible to implement the Perl 5.005 localized options. All options to pcre_study() were also removed. 7. Add other new features from 5.005: $(?<= positive lookbehind $(?a*))*/ (a PCRE_EXTRA facility). Version 1.00 18-Nov-97 ---------------------- 1. Added compile-time macros to support systems such as SunOS4 which don't have memmove() or strerror() but have other things that can be used instead. 2. Arranged that "make clean" removes the executables. Version 0.99 27-Oct-97 ---------------------- 1. Fixed bug in code for optimizing classes with only one character. It was initializing a 32-byte map regardless, which could cause it to run off the end of the memory it had got. 2. Added, conditional on PCRE_EXTRA, the proposed (?>REGEX) construction. Version 0.98 22-Oct-97 ---------------------- 1. Fixed bug in code for handling temporary memory usage when there are more back references than supplied space in the ovector. This could cause segfaults. Version 0.97 21-Oct-97 ---------------------- 1. Added the \X "cut" facility, conditional on PCRE_EXTRA. 2. Optimized negated single characters not to use a bit map. 3. Brought error texts together as macro definitions; clarified some of them; fixed one that was wrong - it said "range out of order" when it meant "invalid escape sequence". 4. Changed some char * arguments to const char *. 5. Added PCRE_NOTBOL and PCRE_NOTEOL (from POSIX). 6. Added the POSIX-style API wrapper in pcreposix.a and testing facilities in pcretest. Version 0.96 16-Oct-97 ---------------------- 1. Added a simple "pgrep" utility to the distribution. 2. Fixed an incompatibility with Perl: "{" is now treated as a normal character unless it appears in one of the precise forms "{ddd}", "{ddd,}", or "{ddd,ddd}" where "ddd" means "one or more decimal digits". 3. Fixed serious bug. If a pattern had a back reference, but the call to pcre_exec() didn't supply a large enough ovector to record the related identifying subpattern, the match always failed. PCRE now remembers the number of the largest back reference, and gets some temporary memory in which to save the offsets during matching if necessary, in order to ensure that backreferences always work. 4. Increased the compatibility with Perl in a number of ways: (a) . no longer matches \n by default; an option PCRE_DOTALL is provided to request this handling. The option can be set at compile or exec time. (b) $ matches before a terminating newline by default; an option PCRE_DOLLAR_ENDONLY is provided to override this (but not in multiline mode). The option can be set at compile or exec time. (c) The handling of \ followed by a digit other than 0 is now supposed to be the same as Perl's. If the decimal number it represents is less than 10 or there aren't that many previous left capturing parentheses, an octal escape is read. Inside a character class, it's always an octal escape, even if it is a single digit. (d) An escaped but undefined alphabetic character is taken as a literal, unless PCRE_EXTRA is set. Currently this just reserves the remaining escapes. (e) {0} is now permitted. (The previous item is removed from the compiled pattern). 5. Changed all the names of code files so that the basic parts are no longer than 10 characters, and abolished the teeny "globals.c" file. 6. Changed the handling of character classes; they are now done with a 32-byte bit map always. 7. Added the -d and /D options to pcretest to make it possible to look at the internals of compilation without having to recompile pcre. Version 0.95 23-Sep-97 ---------------------- 1. Fixed bug in pre-pass concerning escaped "normal" characters such as \x5c or \x20 at the start of a run of normal characters. These were being treated as real characters, instead of the source characters being re-checked. Version 0.94 18-Sep-97 ---------------------- 1. The functions are now thread-safe, with the caveat that the global variables containing pointers to malloc() and free() or alternative functions are the same for all threads. 2. Get pcre_study() to generate a bitmap of initial characters for non- anchored patterns when this is possible, and use it if passed to pcre_exec(). Version 0.93 15-Sep-97 ---------------------- 1. /(b)|(:+)/ was computing an incorrect first character. 2. Add pcre_study() to the API and the passing of pcre_extra to pcre_exec(), but not actually doing anything yet. 3. Treat "-" characters in classes that cannot be part of ranges as literals, as Perl does (e.g. [-az] or [az-]). 4. Set the anchored flag if a branch starts with .* or .*? because that tests all possible positions. 5. Split up into different modules to avoid including unneeded functions in a compiled binary. However, compile and exec are still in one module. The "study" function is split off. 6. The character tables are now in a separate module whose source is generated by an auxiliary program - but can then be edited by hand if required. There are now no calls to isalnum(), isspace(), isdigit(), isxdigit(), tolower() or toupper() in the code. 7. Turn the malloc/free funtions variables into pcre_malloc and pcre_free and make them global. Abolish the function for setting them, as the caller can now set them directly. Version 0.92 11-Sep-97 ---------------------- 1. A repeat with a fixed maximum and a minimum of 1 for an ordinary character (e.g. /a{1,3}/) was broken (I mis-optimized it). 2. Caseless matching was not working in character classes if the characters in the pattern were in upper case. 3. Make ranges like [W-c] work in the same way as Perl for caseless matching. 4. Make PCRE_ANCHORED public and accept as a compile option. 5. Add an options word to pcre_exec() and accept PCRE_ANCHORED and PCRE_CASELESS at run time. Add escapes \A and \I to pcretest to cause it to pass them. 6. Give an error if bad option bits passed at compile or run time. 7. Add PCRE_MULTILINE at compile and exec time, and (?m) as well. Add \M to pcretest to cause it to pass that flag. 8. Add pcre_info(), to get the number of identifying subpatterns, the stored options, and the first character, if set. 9. Recognize C+ or C{n,m} where n >= 1 as providing a fixed starting character. Version 0.91 10-Sep-97 ---------------------- 1. PCRE was failing to diagnose unlimited repeats of subpatterns that could match the empty string as in /(a*)*/. It was looping and ultimately crashing. 2. PCRE was looping on encountering an indefinitely repeated back reference to a subpattern that had matched an empty string, e.g. /(a|)\1*/. It now does what Perl does - treats the match as successful. ****