X-Git-Url: http://ftp.carnet.hr/carnet-debian/scm?p=ossec-hids.git;a=blobdiff_plain;f=src%2Fexternal%2Fpcre2-10.32%2Fdoc%2Fpcre2posix.3;fp=src%2Fexternal%2Fpcre2-10.32%2Fdoc%2Fpcre2posix.3;h=0d8b2c2409a09d1d53860460842ed845cee90d75;hp=0000000000000000000000000000000000000000;hb=3f728675941dc69d4e544d3a880a56240a6e394a;hpb=927951d1c1ad45ba9e7325f07d996154a91c911b diff --git a/src/external/pcre2-10.32/doc/pcre2posix.3 b/src/external/pcre2-10.32/doc/pcre2posix.3 new file mode 100644 index 0000000..0d8b2c2 --- /dev/null +++ b/src/external/pcre2-10.32/doc/pcre2posix.3 @@ -0,0 +1,305 @@ +.TH PCRE2POSIX 3 "15 June 2017" "PCRE2 10.30" +.SH NAME +PCRE2 - Perl-compatible regular expressions (revised API) +.SH "SYNOPSIS" +.rs +.sp +.B #include +.PP +.nf +.B int regcomp(regex_t *\fIpreg\fP, const char *\fIpattern\fP, +.B " int \fIcflags\fP);" +.sp +.B int regexec(const regex_t *\fIpreg\fP, const char *\fIstring\fP, +.B " size_t \fInmatch\fP, regmatch_t \fIpmatch\fP[], int \fIeflags\fP);" +.sp +.B "size_t regerror(int \fIerrcode\fP, const regex_t *\fIpreg\fP," +.B " char *\fIerrbuf\fP, size_t \fIerrbuf_size\fP);" +.sp +.B void regfree(regex_t *\fIpreg\fP); +.fi +. +.SH DESCRIPTION +.rs +.sp +This set of functions provides a POSIX-style API for the PCRE2 regular +expression 8-bit library. See the +.\" HREF +\fBpcre2api\fP +.\" +documentation for a description of PCRE2's native API, which contains much +additional functionality. There are no POSIX-style wrappers for PCRE2's 16-bit +and 32-bit libraries. +.P +The functions described here are just wrapper functions that ultimately call +the PCRE2 native API. Their prototypes are defined in the \fBpcre2posix.h\fP +header file, and on Unix systems the library itself is called +\fBlibpcre2-posix.a\fP, so can be accessed by adding \fB-lpcre2-posix\fP to the +command for linking an application that uses them. Because the POSIX functions +call the native ones, it is also necessary to add \fB-lpcre2-8\fP. +.P +Those POSIX option bits that can reasonably be mapped to PCRE2 native options +have been implemented. In addition, the option REG_EXTENDED is defined with the +value zero. This has no effect, but since programs that are written to the +POSIX interface often use it, this makes it easier to slot in PCRE2 as a +replacement library. Other POSIX options are not even defined. +.P +There are also some options that are not defined by POSIX. These have been +added at the request of users who want to make use of certain PCRE2-specific +features via the POSIX calling interface or to add BSD or GNU functionality. +.P +When PCRE2 is called via these functions, it is only the API that is POSIX-like +in style. The syntax and semantics of the regular expressions themselves are +still those of Perl, subject to the setting of various PCRE2 options, as +described below. "POSIX-like in style" means that the API approximates to the +POSIX definition; it is not fully POSIX-compatible, and in multi-unit encoding +domains it is probably even less compatible. +.P +The header for these functions is supplied as \fBpcre2posix.h\fP to avoid any +potential clash with other POSIX libraries. It can, of course, be renamed or +aliased as \fBregex.h\fP, which is the "correct" name. It provides two +structure types, \fIregex_t\fP for compiled internal forms, and +\fIregmatch_t\fP for returning captured substrings. It also defines some +constants whose names start with "REG_"; these are used for setting options and +identifying error codes. +. +. +.SH "COMPILING A PATTERN" +.rs +.sp +The function \fBregcomp()\fP is called to compile a pattern into an +internal form. By default, the pattern is a C string terminated by a binary +zero (but see REG_PEND below). The \fIpreg\fP argument is a pointer to a +\fBregex_t\fP structure that is used as a base for storing information about +the compiled regular expression. (It is also used for input when REG_PEND is +set.) +.P +The argument \fIcflags\fP is either zero, or contains one or more of the bits +defined by the following macros: +.sp + REG_DOTALL +.sp +The PCRE2_DOTALL option is set when the regular expression is passed for +compilation to the native function. Note that REG_DOTALL is not part of the +POSIX standard. +.sp + REG_ICASE +.sp +The PCRE2_CASELESS option is set when the regular expression is passed for +compilation to the native function. +.sp + REG_NEWLINE +.sp +The PCRE2_MULTILINE option is set when the regular expression is passed for +compilation to the native function. Note that this does \fInot\fP mimic the +defined POSIX behaviour for REG_NEWLINE (see the following section). +.sp + REG_NOSPEC +.sp +The PCRE2_LITERAL option is set when the regular expression is passed for +compilation to the native function. This disables all meta characters in the +pattern, causing it to be treated as a literal string. The only other options +that are allowed with REG_NOSPEC are REG_ICASE, REG_NOSUB, REG_PEND, and +REG_UTF. Note that REG_NOSPEC is not part of the POSIX standard. +.sp + REG_NOSUB +.sp +When a pattern that is compiled with this flag is passed to \fBregexec()\fP for +matching, the \fInmatch\fP and \fIpmatch\fP arguments are ignored, and no +captured strings are returned. Versions of the PCRE library prior to 10.22 used +to set the PCRE2_NO_AUTO_CAPTURE compile option, but this no longer happens +because it disables the use of backreferences. +.sp + REG_PEND +.sp +If this option is set, the \fBreg_endp\fP field in the \fIpreg\fP structure +(which has the type const char *) must be set to point to the character beyond +the end of the pattern before calling \fBregcomp()\fP. The pattern itself may +now contain binary zeros, which are treated as data characters. Without +REG_PEND, a binary zero terminates the pattern and the \fBre_endp\fP field is +ignored. This is a GNU extension to the POSIX standard and should be used with +caution in software intended to be portable to other systems. +.sp + REG_UCP +.sp +The PCRE2_UCP option is set when the regular expression is passed for +compilation to the native function. This causes PCRE2 to use Unicode properties +when matchine \ed, \ew, etc., instead of just recognizing ASCII values. Note +that REG_UCP is not part of the POSIX standard. +.sp + REG_UNGREEDY +.sp +The PCRE2_UNGREEDY option is set when the regular expression is passed for +compilation to the native function. Note that REG_UNGREEDY is not part of the +POSIX standard. +.sp + REG_UTF +.sp +The PCRE2_UTF option is set when the regular expression is passed for +compilation to the native function. This causes the pattern itself and all data +strings used for matching it to be treated as UTF-8 strings. Note that REG_UTF +is not part of the POSIX standard. +.P +In the absence of these flags, no options are passed to the native function. +This means the the regex is compiled with PCRE2 default semantics. In +particular, the way it handles newline characters in the subject string is the +Perl way, not the POSIX way. Note that setting PCRE2_MULTILINE has only +\fIsome\fP of the effects specified for REG_NEWLINE. It does not affect the way +newlines are matched by the dot metacharacter (they are not) or by a negative +class such as [^a] (they are). +.P +The yield of \fBregcomp()\fP is zero on success, and non-zero otherwise. The +\fIpreg\fP structure is filled in on success, and one other member of the +structure (as well as \fIre_endp\fP) is public: \fIre_nsub\fP contains the +number of capturing subpatterns in the regular expression. Various error codes +are defined in the header file. +.P +NOTE: If the yield of \fBregcomp()\fP is non-zero, you must not attempt to +use the contents of the \fIpreg\fP structure. If, for example, you pass it to +\fBregexec()\fP, the result is undefined and your program is likely to crash. +. +. +.SH "MATCHING NEWLINE CHARACTERS" +.rs +.sp +This area is not simple, because POSIX and Perl take different views of things. +It is not possible to get PCRE2 to obey POSIX semantics, but then PCRE2 was +never intended to be a POSIX engine. The following table lists the different +possibilities for matching newline characters in Perl and PCRE2: +.sp + Default Change with +.sp + . matches newline no PCRE2_DOTALL + newline matches [^a] yes not changeable + $ matches \en at end yes PCRE2_DOLLAR_ENDONLY + $ matches \en in middle no PCRE2_MULTILINE + ^ matches \en in middle no PCRE2_MULTILINE +.sp +This is the equivalent table for a POSIX-compatible pattern matcher: +.sp + Default Change with +.sp + . matches newline yes REG_NEWLINE + newline matches [^a] yes REG_NEWLINE + $ matches \en at end no REG_NEWLINE + $ matches \en in middle no REG_NEWLINE + ^ matches \en in middle no REG_NEWLINE +.sp +This behaviour is not what happens when PCRE2 is called via its POSIX +API. By default, PCRE2's behaviour is the same as Perl's, except that there is +no equivalent for PCRE2_DOLLAR_ENDONLY in Perl. In both PCRE2 and Perl, there +is no way to stop newline from matching [^a]. +.P +Default POSIX newline handling can be obtained by setting PCRE2_DOTALL and +PCRE2_DOLLAR_ENDONLY when calling \fBpcre2_compile()\fP directly, but there is +no way to make PCRE2 behave exactly as for the REG_NEWLINE action. When using +the POSIX API, passing REG_NEWLINE to PCRE2's \fBregcomp()\fP function +causes PCRE2_MULTILINE to be passed to \fBpcre2_compile()\fP, and REG_DOTALL +passes PCRE2_DOTALL. There is no way to pass PCRE2_DOLLAR_ENDONLY. +. +. +.SH "MATCHING A PATTERN" +.rs +.sp +The function \fBregexec()\fP is called to match a compiled pattern \fIpreg\fP +against a given \fIstring\fP, which is by default terminated by a zero byte +(but see REG_STARTEND below), subject to the options in \fIeflags\fP. These can +be: +.sp + REG_NOTBOL +.sp +The PCRE2_NOTBOL option is set when calling the underlying PCRE2 matching +function. +.sp + REG_NOTEMPTY +.sp +The PCRE2_NOTEMPTY option is set when calling the underlying PCRE2 matching +function. Note that REG_NOTEMPTY is not part of the POSIX standard. However, +setting this option can give more POSIX-like behaviour in some situations. +.sp + REG_NOTEOL +.sp +The PCRE2_NOTEOL option is set when calling the underlying PCRE2 matching +function. +.sp + REG_STARTEND +.sp +When this option is set, the subject string starts at \fIstring\fP + +\fIpmatch[0].rm_so\fP and ends at \fIstring\fP + \fIpmatch[0].rm_eo\fP, which +should point to the first character beyond the string. There may be binary +zeros within the subject string, and indeed, using REG_STARTEND is the only +way to pass a subject string that contains a binary zero. +.P +Whatever the value of \fIpmatch[0].rm_so\fP, the offsets of the matched string +and any captured substrings are still given relative to the start of +\fIstring\fP itself. (Before PCRE2 release 10.30 these were given relative to +\fIstring\fP + \fIpmatch[0].rm_so\fP, but this differs from other +implementations.) +.P +This is a BSD extension, compatible with but not specified by IEEE Standard +1003.2 (POSIX.2), and should be used with caution in software intended to be +portable to other systems. Note that a non-zero \fIrm_so\fP does not imply +REG_NOTBOL; REG_STARTEND affects only the location and length of the string, +not how it is matched. Setting REG_STARTEND and passing \fIpmatch\fP as NULL +are mutually exclusive; the error REG_INVARG is returned. +.P +If the pattern was compiled with the REG_NOSUB flag, no data about any matched +strings is returned. The \fInmatch\fP and \fIpmatch\fP arguments of +\fBregexec()\fP are ignored (except possibly as input for REG_STARTEND). +.P +The value of \fInmatch\fP may be zero, and the value \fIpmatch\fP may be NULL +(unless REG_STARTEND is set); in both these cases no data about any matched +strings is returned. +.P +Otherwise, the portion of the string that was matched, and also any captured +substrings, are returned via the \fIpmatch\fP argument, which points to an +array of \fInmatch\fP structures of type \fIregmatch_t\fP, containing the +members \fIrm_so\fP and \fIrm_eo\fP. These contain the byte offset to the first +character of each substring and the offset to the first character after the end +of each substring, respectively. The 0th element of the vector relates to the +entire portion of \fIstring\fP that was matched; subsequent elements relate to +the capturing subpatterns of the regular expression. Unused entries in the +array have both structure members set to -1. +.P +A successful match yields a zero return; various error codes are defined in the +header file, of which REG_NOMATCH is the "expected" failure code. +. +. +.SH "ERROR MESSAGES" +.rs +.sp +The \fBregerror()\fP function maps a non-zero errorcode from either +\fBregcomp()\fP or \fBregexec()\fP to a printable message. If \fIpreg\fP is not +NULL, the error should have arisen from the use of that structure. A message +terminated by a binary zero is placed in \fIerrbuf\fP. If the buffer is too +short, only the first \fIerrbuf_size\fP - 1 characters of the error message are +used. The yield of the function is the size of buffer needed to hold the whole +message, including the terminating zero. This value is greater than +\fIerrbuf_size\fP if the message was truncated. +. +. +.SH MEMORY USAGE +.rs +.sp +Compiling a regular expression causes memory to be allocated and associated +with the \fIpreg\fP structure. The function \fBregfree()\fP frees all such +memory, after which \fIpreg\fP may no longer be used as a compiled expression. +. +. +.SH AUTHOR +.rs +.sp +.nf +Philip Hazel +University Computing Service +Cambridge, England. +.fi +. +. +.SH REVISION +.rs +.sp +.nf +Last updated: 15 June 2017 +Copyright (c) 1997-2017 University of Cambridge. +.fi