/* $Source: /u/mark/src/pax/RCS/regexp.c,v $ * * $Revision: 1.2 $ * * regexp.c - regular expression matching * * DESCRIPTION * * Underneath the reformatting and comment blocks which were added to * make it consistent with the rest of the code, you will find a * modified version of Henry Specer's regular expression library. * Henry's functions were modified to provide the minimal regular * expression matching, as required by P1003. Henry's code was * copyrighted, and copy of the copyright message and restrictions * are provided, verbatim, below: * * Copyright (c) 1986 by University of Toronto. * Written by Henry Spencer. Not derived from licensed software. * * Permission is granted to anyone to use this software for any * purpose on any computer system, and to redistribute it freely, * 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 defects in it. * * 2. The origin of this software must not be misrepresented, either * by explicit claim or by omission. * * 3. Altered versions must be plainly marked as such, and must not * be misrepresented as being the original software. * * Beware that some of this code is subtly aware of the way operator * precedence is structured in regular expressions. Serious changes in * regular-expression syntax might require a total rethink. * * AUTHORS * * Mark H. Colburn, NAPS International (mark@jhereg.mn.org) * Henry Spencer, University of Torronto (henry@utzoo.edu) * * Sponsored by The USENIX Association for public distribution. * * $Log: regexp.c,v $ * Revision 1.2 89/02/12 10:05:39 mark * 1.2 release fixes * * Revision 1.1 88/12/23 18:02:32 mark * Initial revision * */ /* Headers */ #include "pax.h" #ifndef lint static char *Ident = "$Id: regexp.c,v 1.2 89/02/12 10:05:39 mark Exp $"; #endif /* * The "internal use only" fields in regexp.h are present to pass info from * compile to execute that permits the execute phase to run lots faster on * simple cases. They are: * * regstart char that must begin a match; '\0' if none obvious * reganch is the match anchored (at beginning-of-line only)? * regmust string (pointer into program) that match must include, or NULL * regmlen length of regmust string * * Regstart and reganch permit very fast decisions on suitable starting points * for a match, cutting down the work a lot. Regmust permits fast rejection * of lines that cannot possibly match. The regmust tests are costly enough * that regcomp() supplies a regmust only if the r.e. contains something * potentially expensive (at present, the only such thing detected is * or + * at the start of the r.e., which can involve a lot of backup). Regmlen is * supplied because the test in regexec() needs it and regcomp() is computing * it anyway. */ /* * Structure for regexp "program". This is essentially a linear encoding * of a nondeterministic finite-state machine (aka syntax charts or * "railroad normal form" in parsing technology). Each node is an opcode * plus a "nxt" pointer, possibly plus an operand. "Nxt" pointers of * all nodes except BRANCH implement concatenation; a "nxt" pointer with * a BRANCH on both ends of it is connecting two alternatives. (Here we * have one of the subtle syntax dependencies: an individual BRANCH (as * opposed to a collection of them) is never concatenated with anything * because of operator precedence.) The operand of some types of node is * a literal string; for others, it is a node leading into a sub-FSM. In * particular, the operand of a BRANCH node is the first node of the branch. * (NB this is *not* a tree structure: the tail of the branch connects * to the thing following the set of BRANCHes.) The opcodes are: */ /* definition number opnd? meaning */ #define END 0 /* no End of program. */ #define BOL 1 /* no Match "" at beginning of line. */ #define EOL 2 /* no Match "" at end of line. */ #define ANY 3 /* no Match any one character. */ #define ANYOF 4 /* str Match any character in this string. */ #define ANYBUT 5 /* str Match any character not in this * string. */ #define BRANCH 6 /* node Match this alternative, or the * nxt... */ #define BACK 7 /* no Match "", "nxt" ptr points backward. */ #define EXACTLY 8 /* str Match this string. */ #define NOTHING 9 /* no Match empty string. */ #define STAR 10 /* node Match this (simple) thing 0 or more * times. */ #define OPEN 20 /* no Mark this point in input as start of * #n. */ /* OPEN+1 is number 1, etc. */ #define CLOSE 30 /* no Analogous to OPEN. */ /* * Opcode notes: * * BRANCH The set of branches constituting a single choice are hooked * together with their "nxt" pointers, since precedence prevents * anything being concatenated to any individual branch. The * "nxt" pointer of the last BRANCH in a choice points to the * thing following the whole choice. This is also where the * final "nxt" pointer of each individual branch points; each * branch starts with the operand node of a BRANCH node. * * BACK Normal "nxt" pointers all implicitly point forward; BACK * exists to make loop structures possible. * * STAR complex '*', are implemented as circular BRANCH structures * using BACK. Simple cases (one character per match) are * implemented with STAR for speed and to minimize recursive * plunges. * * OPEN,CLOSE ...are numbered at compile time. */ /* * A node is one char of opcode followed by two chars of "nxt" pointer. * "Nxt" pointers are stored as two 8-bit pieces, high order first. The * value is a positive offset from the opcode of the node containing it. * An operand, if any, simply follows the node. (Note that much of the * code generation knows about this implicit relationship.) * * Using two bytes for the "nxt" pointer is vast overkill for most things, * but allows patterns to get big without disasters. */ #define OP(p) (*(p)) #define NEXT(p) (((*((p)+1)&0377)<<8) + (*((p)+2)&0377)) #define OPERAND(p) ((p) + 3) /* * Utility definitions. */ #define FAIL(m) { regerror(m); return(NULL); } #define ISMULT(c) ((c) == '*') #define META "^$.[()|*\\" #ifndef CHARBITS #define UCHARAT(p) ((int)*(unsigned char *)(p)) #else #define UCHARAT(p) ((int)*(p)&CHARBITS) #endif /* * Flags to be passed up and down. */ #define HASWIDTH 01 /* Known never to match null string. */ #define SIMPLE 02 /* Simple enough to be STAR operand. */ #define SPSTART 04 /* Starts with * */ #define WORST 0 /* Worst case. */ /* * Global work variables for regcomp(). */ static char *regparse; /* Input-scan pointer. */ static int regnpar; /* () count. */ static char regdummy; static char *regcode; /* Code-emit pointer; ®dummy = don't. */ static long regsize; /* Code size. */ /* * Forward declarations for regcomp()'s friends. */ #ifndef STATIC #define STATIC static #endif STATIC char *reg(int, int *); /* Xn */ STATIC char *regbranch(int *); /* Xn */ STATIC char *regpiece(int *); /* Xn */ STATIC char *regatom(int *); /* Xn */ STATIC char *regnode(char); /* Xn */ STATIC char *regnext(register char *); /* Xn */ STATIC void regc(char); /* Xn */ STATIC void reginsert(char, char *); /* Xn */ STATIC void regtail(char *, char *); /* Xn */ STATIC void regoptail(char *, char *); /* Xn */ #ifdef STRCSPN STATIC size_t strcspn(const char *, const char *); /* Xn */ #endif /* - regcomp - compile a regular expression into internal code * * We can't allocate space until we know how big the compiled form will be, * but we can't compile it (and thus know how big it is) until we've got a * place to put the code. So we cheat: we compile it twice, once with code * generation turned off and size counting turned on, and once "for real". * This also means that we don't allocate space until we are sure that the * thing really will compile successfully, and we never have to move the * code and thus invalidate pointers into it. (Note that it has to be in * one piece because free() must be able to free it all.) * * Beware that the optimization-preparation code in here knows about some * of the structure of the compiled regexp. */ regexp *regcomp(char *exp) /* Xn */ { register regexp *r; register char *scan; register char *longest; register size_t len; int flags; if (exp == (char *)NULL) FAIL("NULL argument"); /* First pass: determine size, legality. */ regparse = exp; regnpar = 1; regsize = 0L; regcode = ®dummy; regc(MAGIC); if (reg(0, &flags) == (char *)NULL) return ((regexp *)NULL); /* Small enough for pointer-storage convention? */ if (regsize >= 32767L) /* Probably could be 65535L. */ FAIL("regexp too big"); /* Allocate space. */ r = (regexp *) malloc(sizeof(regexp) + (unsigned) regsize); if (r == (regexp *) NULL) FAIL("out of space"); /* Second pass: emit code. */ regparse = exp; regnpar = 1; regcode = r->program; regc(MAGIC); if (reg(0, &flags) == NULL) return ((regexp *) NULL); /* Dig out information for optimizations. */ r->regstart = '\0'; /* Worst-case defaults. */ r->reganch = 0; r->regmust = NULL; r->regmlen = 0; scan = r->program + 1; /* First BRANCH. */ if (OP(regnext(scan)) == END) { /* Only one top-level choice. */ scan = OPERAND(scan); /* Starting-point info. */ if (OP(scan) == EXACTLY) r->regstart = *OPERAND(scan); else if (OP(scan) == BOL) r->reganch++; /* * If there's something expensive in the r.e., find the longest * literal string that must appear and make it the regmust. Resolve * ties in favor of later strings, since the regstart check works * with the beginning of the r.e. and avoiding duplication * strengthens checking. Not a strong reason, but sufficient in the * absence of others. */ if (flags & SPSTART) { longest = NULL; len = 0; for (; scan != NULL; scan = regnext(scan)) if (OP(scan) == EXACTLY && strlen(OPERAND(scan)) >= len) { longest = OPERAND(scan); len = strlen(OPERAND(scan)); } r->regmust = longest; r->regmlen = len; } } return (r); } /* - reg - regular expression, i.e. main body or parenthesized thing * * Caller must absorb opening parenthesis. * * Combining parenthesis handling with the base level of regular expression * is a trifle forced, but the need to tie the tails of the branches to what * follows makes it hard to avoid. */ static char *reg(int paren, int *flagp) /* Xn */ { register char *ret; register char *br; register char *ender; register int parno; int flags; *flagp = HASWIDTH; /* Tentatively. */ /* Make an OPEN node, if parenthesized. */ #ifdef DF_TRACE_DEBUG printf("DF_TRACE_DEBUG: static char *reg() in regexp.c\n"); #endif if (paren) { if (regnpar >= NSUBEXP) FAIL("too many ()"); parno = regnpar; regnpar++; ret = regnode((char)(OPEN + parno)); } else ret = (char *)NULL; /* Pick up the branches, linking them together. */ br = regbranch(&flags); if (br == (char *)NULL) return ((char *)NULL); if (ret != (char *)NULL) regtail(ret, br); /* OPEN -> first. */ else ret = br; if (!(flags & HASWIDTH)) *flagp &= ~HASWIDTH; *flagp |= flags & SPSTART; while (*regparse == '|') { regparse++; br = regbranch(&flags); if (br == (char *)NULL) return ((char *)NULL); regtail(ret, br); /* BRANCH -> BRANCH. */ if (!(flags & HASWIDTH)) *flagp &= ~HASWIDTH; *flagp |= flags & SPSTART; } /* Make a closing node, and hook it on the end. */ ender = regnode((char)((paren) ? CLOSE + parno : END)); regtail(ret, ender); /* Hook the tails of the branches to the closing node. */ for (br = ret; br != (char *)NULL; br = regnext(br)) regoptail(br, ender); /* Check for proper termination. */ if (paren && *regparse++ != ')') { FAIL("unmatched ()"); } else if (!paren && *regparse != '\0') { if (*regparse == ')') { FAIL("unmatched ()"); } else FAIL("junk on end");/* "Can't happen". */ /* NOTREACHED */ } return (ret); } /* - regbranch - one alternative of an | operator * * Implements the concatenation operator. */ static char *regbranch(int *flagp) /* Xn */ { register char *ret; register char *chain; register char *latest; int flags; *flagp = WORST; /* Tentatively. */ #ifdef DF_TRACE_DEBUG printf("DF_TRACE_DEBUG: static char *regbranch() in regexp.c\n"); #endif ret = regnode(BRANCH); chain = (char *)NULL; while (*regparse != '\0' && *regparse != '|' && *regparse != ')') { latest = regpiece(&flags); if (latest == (char *)NULL) return ((char *)NULL); *flagp |= flags & HASWIDTH; if (chain == (char *)NULL) /* First piece. */ *flagp |= flags & SPSTART; else regtail(chain, latest); chain = latest; } if (chain == (char *)NULL) /* Loop ran zero times. */ regnode(NOTHING); return (ret); } /* - regpiece - something followed by possible [*] * * Note that the branching code sequence used for * is somewhat optimized: * they use the same NOTHING node as both the endmarker for their branch * list and the body of the last branch. It might seem that this node could * be dispensed with entirely, but the endmarker role is not redundant. */ static char *regpiece(int *flagp) /* Xn */ { register char *ret; register char op; int flags; ret = regatom(&flags); if (ret == (char *)NULL) return ((char *)NULL); op = *regparse; if (!ISMULT(op)) { *flagp = flags; return (ret); } if (!(flags & HASWIDTH)) FAIL("* operand could be empty"); *flagp = (WORST | SPSTART); if (op == '*' && (flags & SIMPLE)) reginsert(STAR, ret); else if (op == '*') { /* Emit x* as (x&|), where & means "self". */ reginsert(BRANCH, ret); /* Either x */ regoptail(ret, regnode(BACK)); /* and loop */ regoptail(ret, ret); /* back */ regtail(ret, regnode(BRANCH)); /* or */ regtail(ret, regnode(NOTHING)); /* null. */ } regparse++; if (ISMULT(*regparse)) FAIL("nested *"); return (ret); } /* - regatom - the lowest level * * Optimization: gobbles an entire sequence of ordinary characters so that * it can turn them into a single node, which is smaller to store and * faster to run. Backslashed characters are exceptions, each becoming a * separate node; the code is simpler that way and it's not worth fixing. */ static char *regatom(int *flagp) /* Xn */ { register char *ret; int flags; *flagp = WORST; /* Tentatively. */ switch (*regparse++) { case '^': ret = regnode(BOL); break; case '$': ret = regnode(EOL); break; case '.': ret = regnode(ANY); *flagp |= HASWIDTH | SIMPLE; break; case '[':{ register int class; register int classend; if (*regparse == '^') { /* Complement of range. */ ret = regnode(ANYBUT); regparse++; } else ret = regnode(ANYOF); if (*regparse == ']' || *regparse == '-') regc(*regparse++); while (*regparse != '\0' && *regparse != ']') { if (*regparse == '-') { regparse++; if (*regparse == ']' || *regparse == '\0') regc('-'); else { class = UCHARAT(regparse - 2) + 1; classend = UCHARAT(regparse); if (class > classend + 1) FAIL("invalid [] range"); for (; class <= classend; class++) regc((char)class); regparse++; } } else regc(*regparse++); } regc('\0'); if (*regparse != ']') FAIL("unmatched []"); regparse++; *flagp |= HASWIDTH | SIMPLE; } break; case '(': ret = reg(1, &flags); if (ret == (char *)NULL) return ((char *)NULL); *flagp |= flags & (HASWIDTH | SPSTART); break; case '\0': case '|': case ')': FAIL("internal urp"); /* Supposed to be caught earlier. */ case '*': FAIL("* follows nothing"); case '\\': if (*regparse == '\0') FAIL("trailing \\"); ret = regnode(EXACTLY); regc(*regparse++); regc('\0'); *flagp |= HASWIDTH | SIMPLE; break; default:{ register uint len; /* Xn */ register char ender; regparse--; len = strcspn(regparse, META); ender = *(regparse + len); if (len > 1 && ISMULT(ender)) len--; /* Back off clear of * operand. */ *flagp |= HASWIDTH; if (len == 1) *flagp |= SIMPLE; ret = regnode(EXACTLY); while (len > 0) { regc(*regparse++); len--; } regc('\0'); } break; } return (ret); } /* - regnode - emit a node */ static char *regnode(char op) /* Xn */ { register char *ret; register char *ptr; ret = regcode; #ifdef DF_TRACE_DEBUG printf("DF_TRACE_DEBUG: static char *regnode() in regexp.c\n"); #endif if (ret == ®dummy) { regsize += 3; return (ret); } ptr = ret; *ptr++ = op; *ptr++ = '\0'; /* Null "nxt" pointer. */ *ptr++ = '\0'; regcode = ptr; return (ret); } /* - regc - emit (if appropriate) a byte of code */ static void regc(char b) /* Xn */ { #ifdef DF_TRACE_DEBUG printf("DF_TRACE_DEBUG: static void regc() in regexp.c\n"); #endif if (regcode != ®dummy) *regcode++ = b; else regsize++; } /* - reginsert - insert an operator in front of already-emitted operand * * Means relocating the operand. */ static void reginsert(char op, char *opnd) /* Xn */ { register char *src; register char *dst; register char *place; #ifdef DF_TRACE_DEBUG printf("DF_TRACE_DEBUG: static void reginsert() in regexp.c\n"); #endif if (regcode == ®dummy) { regsize += 3; return; } src = regcode; regcode += 3; dst = regcode; while (src > opnd) *--dst = *--src; place = opnd; /* Op node, where operand used to be. */ *place++ = op; *place++ = '\0'; *place++ = '\0'; } /* - regtail - set the next-pointer at the end of a node chain */ static void regtail(char *p, char *val) /* Xn */ { register char *scan; register char *temp; register int offset; if (p == ®dummy) return; /* Find last node. */ scan = p; for (;;) { temp = regnext(scan); if (temp == (char *)NULL) break; scan = temp; } if (OP(scan) == BACK) offset = (int)(scan - val); else offset = (int)(val - scan); *(scan + 1) = (offset >> 8) & 0377; *(scan + 2) = offset & 0377; } /* - regoptail - regtail on operand of first argument; nop if operandless */ static void regoptail(char *p, char *val) /* Xn */ { /* "Operandless" and "op != BRANCH" are synonymous in practice. */ if (p == (char *)NULL || p == ®dummy || OP(p) != BRANCH) return; regtail(OPERAND(p), val); } /* * regexec and friends */ /* * Global work variables for regexec(). */ static char *reginput; /* String-input pointer. */ static char *regbol; /* Beginning of input, for ^ check. */ static char **regstartp; /* Pointer to startp array. */ static char **regendp; /* Ditto for endp. */ /* * Forwards. */ STATIC int regtry(regexp *, char *); /* Xn */ STATIC int regmatch(char *); /* Xn */ STATIC int regrepeat(char *); /* Xn */ /* Xn */ #ifdef DEBUG /* Xn */ int regnarrate = 0; /* Xn */ void regdump(regexp *); /* Xn */ STATIC char *regprop(char *); /* Xn */ #endif /* Xn */ /* - regexec - match a regexp against a string */ int regexec(register regexp *prog, register char *string) /* Xn */ { register char *s; /* Be paranoid... */ #ifdef DF_TRACE_DEBUG printf("DF_TRACE_DEBUG: int regexec() in regexp.c\n"); #endif if (prog == (regexp *)NULL || string == (char *)NULL) { regerror("NULL parameter"); return (0); } /* Check validity of program. */ if (UCHARAT(prog->program) != MAGIC) { regerror("corrupted program"); return (0); } /* If there is a "must appear" string, look for it. */ if (prog->regmust != (char *)NULL) { s = string; while ((s = strchr(s, prog->regmust[0])) != (char *)NULL) { if (strncmp(s, prog->regmust, prog->regmlen) == 0) break; /* Found it. */ s++; } if (s == (char *)NULL) /* Not present. */ return (0); } /* Mark beginning of line for ^ . */ regbol = string; /* Simplest case: anchored match need be tried only once. */ if (prog->reganch) return (regtry(prog, string)); /* Messy cases: unanchored match. */ s = string; if (prog->regstart != '\0') /* We know what char it must start with. */ while ((s = strchr(s, prog->regstart)) != (char *)NULL) { if (regtry(prog, s)) return (1); s++; } else /* We don't -- general case. */ do { if (regtry(prog, s)) return (1); } while (*s++ != '\0'); /* Failure. */ return (0); } /* - regtry - try match at specific point */ static int regtry(regexp *prog, char *string) { register int i; register char **sp; register char **ep; reginput = string; regstartp = prog->startp; regendp = prog->endp; sp = prog->startp; ep = prog->endp; for (i = NSUBEXP; i > 0; i--) { *sp++ = (char *)NULL; *ep++ = (char *)NULL; } if (regmatch(prog->program + 1)) { prog->startp[0] = string; prog->endp[0] = reginput; return (1); } else return (0); } /* - regmatch - main matching routine * * Conceptually the strategy is simple: check to see whether the current * node matches, call self recursively to see whether the rest matches, * and then act accordingly. In practice we make some effort to avoid * recursion, in particular by going through "ordinary" nodes (that don't * need to know whether the rest of the match failed) by a loop instead of * by recursion. */ static int regmatch(char *prog) { register char *scan; /* Current node. */ char *nxt; /* nxt node. */ scan = prog; #ifdef DEBUG #ifdef DF_TRACE_DEBUG printf("DF_TRACE_DEBUG: static int regmatch() in regexp.c\n"); #endif if (scan != (char *)NULL && regnarrate) fprintf(stderr, "%s(\n", regprop(scan)); #endif while (scan != (char *)NULL) { #ifdef DEBUG if (regnarrate) fprintf(stderr, "%s...\n", regprop(scan)); #endif nxt = regnext(scan); switch (OP(scan)) { case BOL: if (reginput != regbol) return (0); break; case EOL: if (*reginput != '\0') return (0); break; case ANY: if (*reginput == '\0') return (0); reginput++; break; case EXACTLY:{ register int len; register char *opnd; opnd = OPERAND(scan); /* Inline the first character, for speed. */ if (*opnd != *reginput) return (0); len = strlen(opnd); if (len > 1 && strncmp(opnd, reginput, len) != 0) return (0); reginput += len; } break; case ANYOF: if (*reginput == '\0' || strchr(OPERAND(scan), *reginput) == (char *)NULL) return (0); reginput++; break; case ANYBUT: if (*reginput == '\0' || strchr(OPERAND(scan), *reginput) != (char *)NULL) return (0); reginput++; break; case NOTHING: break; case BACK: break; case OPEN + 1: case OPEN + 2: case OPEN + 3: case OPEN + 4: case OPEN + 5: case OPEN + 6: case OPEN + 7: case OPEN + 8: case OPEN + 9:{ register int no; register char *save; no = OP(scan) - OPEN; save = reginput; if (regmatch(nxt)) { /* * Don't set startp if some later invocation of the same * parentheses already has. */ if (regstartp[no] == (char *)NULL) regstartp[no] = save; return (1); } else return (0); } case CLOSE + 1: case CLOSE + 2: case CLOSE + 3: case CLOSE + 4: case CLOSE + 5: case CLOSE + 6: case CLOSE + 7: case CLOSE + 8: case CLOSE + 9:{ register int no; register char *save; no = OP(scan) - CLOSE; save = reginput; if (regmatch(nxt)) { /* * Don't set endp if some later invocation of the same * parentheses already has. */ if (regendp[no] == (char *)NULL) regendp[no] = save; return (1); } else return (0); } case BRANCH:{ register char *save; if (OP(nxt) != BRANCH) /* No choice. */ nxt = OPERAND(scan); /* Avoid recursion. */ else { do { save = reginput; if (regmatch(OPERAND(scan))) return (1); reginput = save; scan = regnext(scan); } while (scan != (char *)NULL && OP(scan) == BRANCH); return (0); /* NOTREACHED */ } break; /* Xn */ } /* Xn */ case STAR:{ register char nextch; register int no; register char *save; register int minimum; /* * Lookahead to avoid useless match attempts when we know * what character comes next. */ nextch = '\0'; if (OP(nxt) == EXACTLY) nextch = *OPERAND(nxt); minimum = (OP(scan) == STAR) ? 0 : 1; save = reginput; no = regrepeat(OPERAND(scan)); while (no >= minimum) { /* If it could work, try it. */ if (nextch == '\0' || *reginput == nextch) if (regmatch(nxt)) return (1); /* Couldn't or didn't -- back up. */ no--; reginput = save + no; } return (0); } case END: return (1); /* Success! */ default: regerror("memory corruption"); return (0); } scan = nxt; } /* * We get here only if there's trouble -- normally "case END" is the * terminating point. */ regerror("corrupted pointers"); return (0); } /* - regrepeat - repeatedly match something simple, report how many */ static int regrepeat(char *p) { register int count = 0; register char *scan; register char *opnd; scan = reginput; opnd = OPERAND(p); switch (OP(p)) { case ANY: count = strlen(scan); scan += count; break; case EXACTLY: while (*opnd == *scan) { count++; scan++; } break; case ANYOF: while (*scan != '\0' && strchr(opnd, *scan) != (char *)NULL) { count++; scan++; } break; case ANYBUT: while (*scan != '\0' && strchr(opnd, *scan) == (char *)NULL) { count++; scan++; } break; default: /* Oh dear. Called inappropriately. */ regerror("internal foulup"); count = 0; /* Best compromise. */ break; } reginput = scan; return (count); } /* - regnext - dig the "nxt" pointer out of a node */ static char *regnext(register char *p) { register int offset; if (p == ®dummy) return ((char *)NULL); offset = NEXT(p); if (offset == 0) return ((char *)NULL); if (OP(p) == BACK) return (p - offset); else return (p + offset); } #ifdef DEBUG #if 0 /* Xn */ STATIC char *regprop(); #endif /* Xn */ /* - regdump - dump a regexp onto stdout in vaguely comprehensible form */ void regdump(regexp *r) { register char *s; register char op = EXACTLY; /* Arbitrary non-END op. */ register char *nxt; #if 0 /* Xn */ extern char *strchr(); #endif /* Xn */ s = r->program + 1; while (op != END) { /* While that wasn't END last time... */ op = OP(s); printf("%2d%s", s - r->program, regprop(s)); /* Where, what. */ nxt = regnext(s); if (nxt == (char *)NULL) /* nxt ptr. */ printf("(0)"); else printf("(%d)", (s - r->program) + (nxt - s)); s += 3; if (op == ANYOF || op == ANYBUT || op == EXACTLY) { /* Literal string, where present. */ while (*s != '\0') { putchar(*s); s++; } s++; } putchar('\n'); } /* Header fields of interest. */ if (r->regstart != '\0') printf("start `%c' ", r->regstart); if (r->reganch) printf("anchored "); if (r->regmust != (char *)NULL) printf("must have \"%s\"", r->regmust); printf("\n"); } /* - regprop - printable representation of opcode */ static char *regprop(char *op) { register char *p; static char buf[50]; strcpy(buf, ":"); switch (OP(op)) { case BOL: p = "BOL"; break; case EOL: p = "EOL"; break; case ANY: p = "ANY"; break; case ANYOF: p = "ANYOF"; break; case ANYBUT: p = "ANYBUT"; break; case BRANCH: p = "BRANCH"; break; case EXACTLY: p = "EXACTLY"; break; case NOTHING: p = "NOTHING"; break; case BACK: p = "BACK"; break; case END: p = "END"; break; case OPEN + 1: case OPEN + 2: case OPEN + 3: case OPEN + 4: case OPEN + 5: case OPEN + 6: case OPEN + 7: case OPEN + 8: case OPEN + 9: sprintf(buf + strlen(buf), "OPEN%d", OP(op) - OPEN); p = (char *)NULL; break; case CLOSE + 1: case CLOSE + 2: case CLOSE + 3: case CLOSE + 4: case CLOSE + 5: case CLOSE + 6: case CLOSE + 7: case CLOSE + 8: case CLOSE + 9: sprintf(buf + strlen(buf), "CLOSE%d", OP(op) - CLOSE); p = (char *)NULL; break; case STAR: p = "STAR"; break; default: regerror("corrupted opcode"); break; } if (p != (char *)NULL) strcat(buf, p); return (buf); } #endif /* * The following is provided for those people who do not have strcspn() in * their C libraries. They should get off their butts and do something * about it; at least one public-domain implementation of those (highly * useful) string routines has been published on Usenet. */ #ifdef STRCSPN /* * strcspn - find length of initial segment of s1 consisting entirely * of characters not from s2 */ static size_t strcspn(const char *s1, const char *s2) /* Xn */ { #ifdef __STDC__ /* Xn */ register const char *scan1; /* Xn */ register const char *scan2; /* Xn */ register size_t count; /* Xn */ #else /* Xn */ register char *scan1; register char *scan2; register uint count; /* Xn */ #endif /* Xn */ count = 0; for (scan1 = s1; *scan1 != '\0'; scan1++) { for (scan2 = s2; *scan2 != '\0';) /* ++ moved down. */ if (*scan1 == *scan2++) return (count); count++; } return (count); } #endif /* - regsub - perform substitutions after a regexp match */ void regsub(regexp *prog, char *source, char *dest) { register char *src; register char *dst; register char c; register int no; register int len; extern char *strncpy(); if (prog == (regexp *)NULL || source == (char *)NULL || dest == (char *)NULL) { regerror("NULL parm to regsub"); return; } if (UCHARAT(prog->program) != MAGIC) { regerror("damaged regexp fed to regsub"); return; } src = source; dst = dest; while ((c = *src++) != '\0') { if (c == '&') no = 0; else if (c == '\\' && '0' <= *src && *src <= '9') no = *src++ - '0'; else no = -1; if (no < 0) { /* Ordinary character. */ if (c == '\\' && (*src == '\\' || *src == '&')) c = *src++; *dst++ = c; } else if (prog->startp[no] != (char *)NULL && prog->endp[no] != (char *)NULL) { len = (int)(prog->endp[no] - prog->startp[no]); strncpy(dst, prog->startp[no], len); dst += len; if (len != 0 && *(dst - 1) == '\0') { /* strncpy hit NUL. */ regerror("damaged match string"); return; } } } *dst++ = '\0'; } void regerror(char *s) { fprintf(stderr, "regexp(3): %s", s); exit(1); }