/*~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ * $Id: regexec.c,v 1.2 2005/02/22 22:01:25 swift Exp $ *~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/ /** This C source code implements the regcomp() component of a POSIX regular expression parser library. Henry Spencer was the author of the C source code library on which this is based. Most of the source remains unmodified from Spencer's version. The following copyright notice was included with Henry's distribution: \begin{verbatim} Copyright 1992, 1993, 1994, 1997 Henry Spencer. All rights reserved. This software is not subject to any license of the American Telephone and Telegraph Company or of the Regents of the University of California. Permission is granted to anyone to use this software for any purpose on any computer system, and to alter it and redistribute it, subject to the following restrictions: 1. The author is not responsible for the consequences of use of this software, no matter how awful, even if they arise from flaws in it. 2. The origin of this software must not be misrepresented, either by explicit claim or by omission. Since few users ever read sources, credits must appear in the documentation. 3. Altered versions must be plainly marked as such, and must not be misrepresented as being the original software. Since few users ever read sources, credits must appear in the documentation. 4. This notice may not be removed or altered. \end{verbatim} No modifications have been made to the functionality of regcomp(). The nature of the modifications are mostly repackaging of the source code. The following documetation was cut from the man (3) page that accompanied Spencer's distribution. \begin{verbatim} REGEX(3) REGEX(3) NAME regcomp, regexec, regerror, regfree - regular-expression library SYNOPSIS #include int regexec(const regex_t *preg, const char *string, size_t nmatch, regmatch_t pmatch[], int eflags); DESCRIPTION These routines implement POSIX 1003.2 regular expressions (``RE''s); see regex(7). Regcomp compiles an RE written as a string into an internal form, regexec matches that internal form against a string and reports results, regerror transforms error codes from either into human- readable messages, and regfree frees any dynamically-allo- cated storage used by the internal form of an RE. The header declares two structure types, regex_t and regmatch_t, the former for compiled internal forms and the latter for match reporting. It also declares the four functions, a type regoff_t, and a number of constants with names starting with ``REG_''. Regexec matches the compiled RE pointed to by preg against the string, subject to the flags in eflags, and reports results using nmatch, pmatch, and the returned value. The RE must have been compiled by a previous invocation of regcomp. The compiled form is not altered during execu- tion of regexec, so a single compiled RE can be used simultaneously by multiple threads. By default, the NUL-terminated string pointed to by string is considered to be the text of an entire line, with the NUL indicating the end of the line. (That is, any other end-of-line marker is considered to have been removed and replaced by the NUL.) The eflags argument is the bitwise OR of zero or more of the following flags: REG_NOTBOL The first character of the string is not the beginning of a line, so the `^' anchor should not match before it. This does not affect the behavior of newlines under REG_NEWLINE. REG_NOTEOL The NUL terminating the string does not end a line, so the `$' anchor should not match before it. This does not affect the behav- ior of newlines under REG_NEWLINE. REG_STARTEND The string is considered to start at string + pmatch[0].rm_so and to have a ter- minating NUL located at string + pmatch[0].rm_eo (there need not actually be a NUL at that location), regardless of the value of nmatch. See below for the defini- tion of pmatch and nmatch. This is an extension, compatible with but not specified by POSIX 1003.2, and should be used with caution in software intended to be portable to other systems. Note that a non-zero rm_so does not imply REG_NOTBOL; REG_STAR- TEND affects only the location of the string, not how it is matched. See regex(7) for a discussion of what is matched in situa- tions where an RE or a portion thereof could match any of several substrings of string. Normally, regexec returns 0 for success and the non-zero code REG_NOMATCH for failure. Other non-zero error codes may be returned in exceptional situations; see DIAGNOS- TICS. If REG_NOSUB was specified in the compilation of the RE, or if nmatch is 0, regexec ignores the pmatch argument (but see below for the case where REG_STARTEND is speci- fied). Otherwise, pmatch points to an array of nmatch structures of type regmatch_t. Such a structure has at least the members rm_so and rm_eo, both of type regoff_t (a signed arithmetic type at least as large as an off_t and a ssize_t), containing respectively the offset of the first character of a substring and the offset of the first character after the end of the substring. Offsets are measured from the beginning of the string argument given to regexec. An empty substring is denoted by equal off- sets, both indicating the character following the empty substring. The 0th member of the pmatch array is filled in to indi- cate what substring of string was matched by the entire RE. Remaining members report what substring was matched by parenthesized subexpressions within the RE; member i reports subexpression i, with subexpressions counted (starting at 1) by the order of their opening parentheses in the RE, left to right. Unused entries in the array-- corresponding either to subexpressions that did not par- ticipate in the match at all, or to subexpressions that do not exist in the RE (that is, i > preg->re_nsub)--have both rm_so and rm_eo set to -1. If a subexpression par- ticipated in the match several times, the reported sub- string is the last one it matched. (Note, as an example in particular, that when the RE `(b*)+' matches `bbb', the parenthesized subexpression matches the three `b's and then an infinite number of empty strings following the last `b', so the reported substring is one of the emp- ties.) If REG_STARTEND is specified, pmatch must point to at least one regmatch_t (even if nmatch is 0 or REG_NOSUB was specified), to hold the input offsets for REG_STARTEND. Use for output is still entirely controlled by nmatch; if nmatch is 0 or REG_NOSUB was specified, the value of pmatch[0] will not be changed by a successful regexec. None of these functions references global variables except for tables of constants; all are safe for use from multi- ple threads if the arguments are safe. IMPLEMENTATION CHOICES There are a number of decisions that 1003.2 leaves up to the implementor, either by explicitly saying ``undefined'' or by virtue of them being forbidden by the RE grammar. This implementation treats them as follows. See regex(7) for a discussion of the definition of case- independent matching. There is no particular limit on the length of REs, except insofar as memory is limited. Memory usage is approxi- mately linear in RE size, and largely insensitive to RE complexity, except for bounded repetitions. See BUGS for one short RE using them that will run almost any system out of memory. A backslashed character other than one specifically given a magic meaning by 1003.2 (such magic meanings occur only in obsolete [``basic''] REs) is taken as an ordinary char- acter. Any unmatched [ is a REG_EBRACK error. Equivalence classes cannot begin or end bracket-expression ranges. The endpoint of one range cannot begin another. RE_DUP_MAX, the limit on repetition counts in bounded rep- etitions, is 255. A repetition operator (?, *, +, or bounds) cannot follow another repetition operator. A repetition operator cannot begin an expression or subexpression or follow `^' or `|'. `|' cannot appear first or last in a (sub)expression or after another `|', i.e. an operand of `|' cannot be an empty subexpression. An empty parenthesized subexpres- sion, `()', is legal and matches an empty (sub)string. An empty string is not a legal RE. A `{' followed by a digit is considered the beginning of bounds for a bounded repetition, which must then follow the syntax for bounds. A `{' not followed by a digit is considered an ordinary character. `^' and `$' beginning and ending subexpressions in obso- lete (``basic'') REs are anchors, not ordinary characters. SEE ALSO POSIX 1003.2, sections 2.8 (Regular Expression Notation) and B.5 (C Binding for Regular Expression Matching). DIAGNOSTICS Non-zero error codes from regcomp and regexec include the following: REG_NOMATCH regexec() failed to match REG_BADPAT invalid regular expression REG_ECOLLATE invalid collating element REG_ECTYPE invalid character class REG_EESCAPE \ applied to unescapable character REG_ESUBREG invalid backreference number REG_EBRACK brackets [ ] not balanced REG_EPAREN parentheses ( ) not balanced REG_EBRACE braces { } not balanced REG_BADBR invalid repetition count(s) in { } REG_ERANGE invalid character range in [ ] REG_ESPACE ran out of memory REG_BADRPT ?, *, or + operand invalid REG_EMPTY empty (sub)expression REG_ASSERT ``can't happen''--you found a bug REG_INVARG invalid argument, e.g. negative-length string HISTORY Written by Henry Spencer, henry@zoo.toronto.edu. BUGS This is an alpha release with known defects. Please report problems. There is one known functionality bug. The implementation of internationalization is incomplete: the locale is always assumed to be the default one of 1003.2, and only the collating elements etc. of that locale are available. The back-reference code is subtle and doubts linger about its correctness in complex cases. Regexec performance is poor. This will improve with later releases. Nmatch exceeding 0 is expensive; nmatch exceeding 1 is worse. Regexec is largely insensitive to RE complexity except that back references are massively expensive. RE length does matter; in particular, there is a strong speed bonus for keeping RE length under about 30 characters, with most special characters counting roughly double. \end{verbatim} * RCS log of revisions to the C source code. * * \begin{verbatim} * $Log: regexec.c,v $ * Revision 1.2 2005/02/22 22:01:25 swift * Eliminated GNU regex implementation. * * Revision 1.2 2003/07/02 17:27:20 swift * The name of the file 'regengine.c' was shortened to 'regengin.c' for * conformance with the ANSI standard and because the HiTech compiler used to * write embedded firmware has a limit of 8 characters for filenames (excluding * extension) in include statements. * * Revision 1.1 2002/10/08 23:54:23 swift * Initial revision * \end{verbatim} *~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~*/ #define RegexecChangeLog "$RCSfile: regexec.c,v $ $Revision: 1.2 $ $Date: 2005/02/22 22:01:25 $" /* * the outer shell of regexec() * * This file includes regengine.c *twice*, after muchos fiddling with the * macros that code uses. This lets the same code operate on two different * representations for state sets. */ #include #include #include #include #include #include "regex.h" #include "regutils.h" #include "regex2.h" #ifdef REDEBUG static int nope = 0; /* for use in asserts; shuts lint up */ #endif /* REDEBUG */ /* macros for manipulating states, small version */ #define states unsigned #define states1 unsigned /* for later use in regexec() decision */ #define CLEAR(v) ((v) = 0) #define SET0(v, n) ((v) &= ~((unsigned)1 << (n))) #define SET1(v, n) ((v) |= (unsigned)1 << (n)) #define ISSET(v, n) ((v) & ((unsigned)1 << (n))) #define ASSIGN(d, s) ((d) = (s)) #define EQ(a, b) ((a) == (b)) #define STATEVARS int dummy /* dummy version */ #define STATESETUP(m, n) /* nothing */ #define STATETEARDOWN(m) /* nothing */ #define SETUP(v) ((v) = 0) #define onestate unsigned #define INIT(o, n) ((o) = (unsigned)1 << (n)) #define INC(o) ((o) <<= 1) #define ISSTATEIN(v, o) ((v) & (o)) /* some abbreviations; note that some of these know variable names! */ /* do "if I'm here, I can also be there" etc without branches */ #define FWD(dst, src, n) ((dst) |= ((unsigned)(src)&(here)) << (n)) #define BACK(dst, src, n) ((dst) |= ((unsigned)(src)&(here)) >> (n)) #define ISSETBACK(v, n) ((v) & ((unsigned)here >> (n))) /* function names */ #define SNAMES /* regengine.c looks after details */ #include "regengin.c" /* now undo things */ #undef states #undef CLEAR #undef SET0 #undef SET1 #undef ISSET #undef ASSIGN #undef EQ #undef STATEVARS #undef STATESETUP #undef STATETEARDOWN #undef SETUP #undef onestate #undef INIT #undef INC #undef ISSTATEIN #undef FWD #undef BACK #undef ISSETBACK #undef SNAMES /* macros for manipulating states, large version */ #define states char * #define CLEAR(v) memset(v, 0, m->g->nstates) #define SET0(v, n) ((v)[n] = 0) #define SET1(v, n) ((v)[n] = 1) #define ISSET(v, n) ((v)[n]) #define ASSIGN(d, s) memcpy(d, s, m->g->nstates) #define EQ(a, b) (memcmp(a, b, m->g->nstates) == 0) #define STATEVARS int vn; char *space #define STATESETUP(m, nv) { (m)->space = malloc((nv)*(m)->g->nstates); \ if ((m)->space == NULL) return(REG_ESPACE); \ (m)->vn = 0; } #define STATETEARDOWN(m) { free((m)->space); } #define SETUP(v) ((v) = &m->space[m->vn++ * m->g->nstates]) #define onestate int #define INIT(o, n) ((o) = (n)) #define INC(o) ((o)++) #define ISSTATEIN(v, o) ((v)[o]) /* some abbreviations; note that some of these know variable names! */ /* do "if I'm here, I can also be there" etc without branches */ #define FWD(dst, src, n) ((dst)[here+(n)] |= (src)[here]) #define BACK(dst, src, n) ((dst)[here-(n)] |= (src)[here]) #define ISSETBACK(v, n) ((v)[here - (n)]) /* function names */ #define LNAMES /* flag */ #include "regengin.c" /* - regexec - interface for matching = extern int regexec(const regex_t *, const char *, size_t, \ = regmatch_t [], int); = #define REG_NOTBOL 00001 = #define REG_NOTEOL 00002 = #define REG_STARTEND 00004 = #define REG_TRACE 00400 // tracing of execution = #define REG_LARGE 01000 // force large representation = #define REG_BACKR 02000 // force use of backref code * * We put this here so we can exploit knowledge of the state representation * when choosing which matcher to call. Also, by this point the matchers * have been prototyped. */ int /* 0 success, REG_NOMATCH failure */ regexec(preg, string, nmatch, pmatch, eflags) const regex_t *preg; const char *string; size_t nmatch; regmatch_t pmatch[]; int eflags; { register struct re_guts *g = preg->re_g; #ifdef REDEBUG # define GOODFLAGS(f) (f) #else # define GOODFLAGS(f) ((f)&(REG_NOTBOL|REG_NOTEOL|REG_STARTEND)) #endif if (preg->re_magic != MAGIC1 || g->magic != MAGIC2) return(REG_BADPAT); assert(!(g->iflags&BAD)); if (g->iflags&BAD) /* backstop for no-debug case */ return(REG_BADPAT); eflags = GOODFLAGS(eflags); if (g->nstates <= (sopno)(CHAR_BIT*sizeof(states1)) && !(eflags®_LARGE)) return(smatcher(g, (char *)string, nmatch, pmatch, eflags)); else return(lmatcher(g, (char *)string, nmatch, pmatch, eflags)); }