/*
*
* 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.
*
*
* This version modified by Ian Phillipps to return pointer to terminating
* NUL on substitution string. [ Temp mail address ex-igp@camcon.co.uk ]
*
* Altered by amylaar to support excompatible option and the
* operators \< and >\ . ( 7.Sep. 1991 )
*
* regsub altered by amylaar to take an additional parameter specifying
* maximum number of bytes that can be written to the memory region
* pointed to by dest
*
* 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.
*
*/
/* Headers */
#include "std.h"
#include "regexp.h"
#include "lpc_incl.h"
#include "comm.h"
#include "ed.h"
/*
* 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.
*/
/*
* The first byte of the regexp internal "program" is actually this magic
* number; the start node begins in the second byte.
*/
#define MAGIC 0234
/*
* 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 PLUS 11 /* node Match this (simple) thing 1 or more
* times. */
#define WORDSTART 12 /* node matching a start of a word */
#define WORDEND 13 /* node matching an end of a word */
#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,PLUS '?', and complex '*' and '+', are implemented as circular
* BRANCH structures using BACK. Simple cases (one character
* per match) are implemented with STAR and PLUS 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))
/* stralloc.h */
#undef NEXT
#define NEXT(p) (((*((p)+1)&0377)<<8) + (*((p)+2)&0377))
#define OPERAND(p) ((p) + 3)
/*
* Utility definitions.
*/
#define SPECIAL 0x100
#define LBRAC ('('|SPECIAL)
#define RBRAC (')'|SPECIAL)
#define ASTERIX ('*'|SPECIAL)
#define PLUSS ('+'|SPECIAL)
#define QMARK ('?'|SPECIAL)
#define OR_OP ('|'|SPECIAL)
#define DOLLAR ('$'|SPECIAL)
#define DOT ('.'|SPECIAL)
#define CARET ('^'|SPECIAL)
#define LSQBRAC ('['|SPECIAL)
#define RSQBRAC (']'|SPECIAL)
#define LSHBRAC ('<'|SPECIAL)
#define RSHBRAC ('>'|SPECIAL)
#define FAIL(m) { regerror(m); return(NULL); }
#define ISMULT(c) ((c) == ASTERIX || (c) == PLUSS || (c) == QMARK)
#define META "^$.[()|?+*\\"
/* Linux seems to define CHARBITS to 8 in values.h; not sure what system
* defines CHARBITS in a form we can use or how to tell (check in configure?)
* Just use 8 bits for now.
*/
#if 0
#if defined(linux)
# ifndef CHARBITS
# define CHARBITS 0xff
# endif
# define UCHARAT(p) ((int)*(unsigned char *)(p))
#else
# ifndef CHARBITS
# define CHARBITS 0xff
# define UCHARAT(p) ((int)*(unsigned char *)(p))
# else
# define UCHARAT(p) ((int)*(p)&CHARBITS)
# endif
#endif
#else
# undef CHARBITS
# define CHARBITS 0xff
# define UCHARAT(p) ((int) *(unsigned char *)(p))
#endif
#define ISWORDPART(c) ( isalnum((unsigned char)c) || (c) == '_' )
/*
* Flags to be passed up and down.
*/
#define HASWIDTH 01 /* Known never to match null string. */
#define SIMPLE 02 /* Simple enough to be STAR/PLUS operand. */
#define SPSTART 04 /* Starts with * or +. */
#define WORST 0 /* Worst case. */
/*
* Global work variables for regcomp().
*/
int regexp_user;
const char *regexp_error;
static short *regparse; /* Input-scan pointer. */
static int regnpar; /* () count. */
static char regdummy;
static char *regcode; /* Code-emit pointer; ®dummy = don't. */
static int regsize; /* Code size. */
/*
* Forward declarations for regcomp()'s friends.
*/
#ifndef STATIC
#define STATIC static
#endif
STATIC char *reg PROT((int, int *));
STATIC char *regbranch PROT((int *));
STATIC char *regpiece PROT((int *));
STATIC char *regatom PROT((int *));
STATIC char *regnode PROT((char));
STATIC char *regnext PROT((char *));
STATIC void regc PROT((char));
STATIC void reginsert PROT((char, char *));
STATIC void regtail PROT((char *, char *));
STATIC void regoptail PROT((char *, char *));
#ifdef STRCSPN
STATIC int strcspn();
#endif
STATIC void regerror P1(const char *, s) {
switch (regexp_user) {
case ED_REGEXP:
ED_OUTPUTV(ED_DEST, "ed: regular expression error: %s", s);
break;
case EFUN_REGEXP:
regexp_error = s;
break;
}
}
/*
- 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 P2(unsigned char *, exp,
int, excompat) /* \( \) operators like in unix ex */
{
register regexp *r;
register unsigned char *scan;
register char *longest;
register int len;
int flags;
short *exp2, *dest, c;
if (!exp)
FAIL("NULL argument\n");
exp2 = (short *)
DXALLOC((strlen((char *)exp) + 1) * (sizeof(short[8]) / sizeof(char[8])),
TAG_TEMPORARY, "regcomp: 1");
for (scan = exp, dest = exp2; (c = *scan++);) {
switch (c) {
case '(':
case ')':
*dest++ = excompat ? c : c | SPECIAL;
break;
case '.':
case '*':
case '+':
case '?':
case '|':
case '$':
case '^':
case '[':
case ']':
*dest++ = c | SPECIAL;
break;
case '\\':
switch (c = *scan++) {
case 0:
FREE(exp2);
FAIL("Regular expression cannot end with '\\'. Use \"\\\\\".\n");
break;
case '(':
case ')':
*dest++ = excompat ? c | SPECIAL : c;
break;
case '<':
case '>':
*dest++ = c | SPECIAL;
break;
case '{':
case '}':
FREE(exp2);
FAIL("sorry, unimplemented operator\n");
case 'b':
*dest++ = '\b';
break;
case 't':
*dest++ = '\t';
break;
case 'r':
*dest++ = '\r';
break;
default:
*dest++ = c;
}
break;
default:
*dest++ = c;
}
}
*dest = 0;
/* First pass: determine size, legality. */
regparse = exp2;
regnpar = 1;
regsize = 0L;
regcode = ®dummy;
regc((char) MAGIC);
if (reg(0, &flags) == (char *) NULL) {
FREE(exp2);
return ((regexp *) NULL);
}
/* Small enough for pointer-storage convention? */
if (regsize >= 32767L) /* Probably could be 65535L. */
{
FREE(exp2);
FAIL("regexp too big\n");
}
/* Allocate space. */
r = (regexp *) DXALLOC(sizeof(regexp) + (unsigned) regsize,
TAG_TEMPORARY, "regcomp: 2");
if (r == (regexp *) NULL) {
FREE(exp2);
FAIL("out of space\n");
}
/* Second pass: emit code. */
regparse = exp2;
regnpar = 1;
regcode = (char *)(r->program);
regc((char) MAGIC);
if (reg(0, &flags) == NULL) {
FREE(exp2);
FREE(r);
return ((regexp *) NULL);
}
/* Dig out information for optimizations. */
r->regstart = '\0'; /* Worst-case defaults. */
r->reganch = 0;
r->regmust = NULL;
r->regmlen = 0;
scan = (unsigned char *)(r->program + 1); /* First BRANCH. */
if (OP(regnext((char *)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 = (unsigned char *)regnext((char *)scan)) {
char *tmp = (char *)OPERAND(scan);
int tlen;
if (OP(scan) == EXACTLY && (tlen = strlen(tmp)) >= len) {
longest = tmp;
len = tlen;
}
}
r->regmust = longest;
r->regmlen = len;
}
}
FREE((char *) exp2);
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 P2(int, paren, /* Parenthesized? */
int *, flagp)
{
register char *ret;
register char *br;
register char *ender;
register int parno = 0;
int flags;
*flagp = HASWIDTH; /* Tentatively. */
/* Make an OPEN node, if parenthesized. */
if (paren) {
if (regnpar >= NSUBEXP)
FAIL("too many ()\n");
parno = regnpar;
regnpar++;
ret = regnode(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 == OR_OP) {
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((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++ != RBRAC) {
FAIL("unmatched ()\n");
} else if (!paren && *regparse != '\0') {
if (*regparse == RBRAC) {
FAIL("unmatched ()\n");
} else
FAIL("junk on end\n");/* "Can't happen". */
/* NOTREACHED */
}
return (ret);
}
/*
- regbranch - one alternative of an | operator
*
* Implements the concatenation operator.
*/
static char *regbranch P1(int *, flagp)
{
register char *ret;
register char *chain;
register char *latest;
int flags;
*flagp = WORST; /* Tentatively. */
ret = regnode(BRANCH);
chain = (char *) NULL;
while (*regparse != '\0' && *regparse != OR_OP && *regparse != RBRAC) {
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 ? and the general cases of
* * and + are 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 P1(int *, flagp)
{
register char *ret;
register short op;
register char *nxt;
int flags;
ret = regatom(&flags);
if (ret == (char *) NULL)
return ((char *) NULL);
op = *regparse;
if (!ISMULT(op)) {
*flagp = flags;
return (ret);
}
if (!(flags & HASWIDTH) && op != QMARK)
FAIL("*+ operand could be empty\n");
*flagp = (op != PLUSS) ? (WORST | SPSTART) : (WORST | HASWIDTH);
if (op == ASTERIX && (flags & SIMPLE))
reginsert(STAR, ret);
else if (op == ASTERIX) {
/* 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. */
} else if (op == PLUSS && (flags & SIMPLE))
reginsert(PLUS, ret);
else if (op == PLUSS) {
/* Emit x+ as x(&|), where & means "self". */
nxt = regnode(BRANCH); /* Either */
regtail(ret, nxt);
regtail(regnode(BACK), ret); /* loop back */
regtail(nxt, regnode(BRANCH)); /* or */
regtail(ret, regnode(NOTHING)); /* null. */
} else if (op == QMARK) {
/* Emit x? as (x|) */
reginsert(BRANCH, ret); /* Either x */
regtail(ret, regnode(BRANCH)); /* or */
nxt = regnode(NOTHING); /* null. */
regtail(ret, nxt);
regoptail(ret, nxt);
}
regparse++;
if (ISMULT(*regparse))
FAIL("nested *?+\n");
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.
*/
static char *regatom P1(int *, flagp)
{
register char *ret;
int flags;
*flagp = WORST; /* Tentatively. */
switch (*regparse++) {
case CARET:
ret = regnode(BOL);
break;
case DOLLAR:
ret = regnode(EOL);
break;
case DOT:
ret = regnode(ANY);
*flagp |= HASWIDTH | SIMPLE;
break;
case LSHBRAC:
ret = regnode(WORDSTART);
break;
case RSHBRAC:
ret = regnode(WORDEND);
break;
case LSQBRAC:{
register int class;
register int classend;
if (*regparse == CARET) { /* Complement of range. */
ret = regnode(ANYBUT);
regparse++;
} else
ret = regnode(ANYOF);
if (*regparse == RSQBRAC || *regparse == '-')
regc(*regparse++);
while (*regparse != '\0' && *regparse != RSQBRAC) {
if (*regparse == '-') {
regparse++;
if (*regparse == RSQBRAC || *regparse == '\0')
regc('-');
else {
class = (CHARBITS & *(regparse - 2)) + 1;
classend = (CHARBITS & *(regparse));
if (class > classend + 1)
FAIL("invalid [] range\n");
for (; class <= classend; class++)
regc(class);
regparse++;
}
} else
regc(*regparse++);
}
regc('\0');
if (*regparse != RSQBRAC)
FAIL("unmatched []\n");
regparse++;
*flagp |= HASWIDTH | SIMPLE;
}
break;
case LBRAC:
ret = reg(1, &flags);
if (ret == (char *) NULL)
return ((char *) NULL);
*flagp |= flags & (HASWIDTH | SPSTART);
break;
case '\0':
case OR_OP:
case RBRAC:
FAIL("internal urp\n"); /* Supposed to be caught earlier. */
break;
case ASTERIX:
FAIL("* follows nothing\n");
break;
case PLUSS:
FAIL("+ follows nothing\n");
break;
case QMARK:
FAIL("? follows nothing\n");
break;
default:{
register int len;
register short ender;
regparse--;
for (len = 0; regparse[len] &&
!(regparse[len] & SPECIAL) && regparse[len] != RSQBRAC; len++);
if (len <= 0) {
FAIL("unexpected ]\n");
}
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 P1(char, op)
{
register char *ret;
register char *ptr;
ret = regcode;
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 P1(char, b)
{
if (regcode != ®dummy)
*regcode++ = b;
else
regsize++;
}
/*
- reginsert - insert an operator in front of already-emitted operand
*
* Means relocating the operand.
*/
static void reginsert P2(char, op, char *, opnd)
{
register char *src;
register char *dst;
register char *place;
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 P2(char *, p, char *, val)
{
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 = scan - val;
else
offset = val - scan;
*(scan + 1) = (offset >> 8) & 0377;
*(scan + 2) = offset & 0377;
}
/*
- regoptail - regtail on operand of first argument; nop if operandless
*/
static void regoptail P2(char *, p, char *, val)
{
/* "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 const char *reginput; /* String-input pointer. */
static const char *regbol; /* Beginning of input, for ^ check. */
static const char **regstartp; /* Pointer to startp array. */
static const char **regendp; /* Ditto for endp. */
/*
* Forwards.
*/
STATIC int regtry PROT((regexp *, const char *));
STATIC int regmatch PROT((char *));
STATIC int regrepeat PROT((char *));
#ifdef DEBUG
int regnarrate = 0;
void regdump PROT((regexp *));
STATIC char *regprop PROT((char *));
#endif
/*
- regexec - match a regexp against a string
*/
int regexec P2(register regexp *, prog, register const char *, string)
{
register const char *s;
/* Be paranoid... */
if (prog == (regexp *) NULL || string == (char *) NULL) {
regerror("NULL parameter\n");
return (0);
}
/* Check validity of program. */
if (UCHARAT(prog->program) != MAGIC) {
regerror("corrupted program\n");
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 P2(regexp *, prog, const char *, string)
{
register int i;
register const char **sp;
register const 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 P1(char *, prog)
{
register char *scan; /* Current node. */
char *nxt; /* nxt node. */
scan = prog;
#ifdef DEBUG
if (scan != (char *) NULL && regnarrate)
debug_message("%s(\n", regprop(scan));
#endif
while (scan != (char *) NULL) {
#ifdef DEBUG
if (regnarrate)
debug_message("%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 WORDSTART:
if (reginput == regbol)
break;
if (*reginput == '\0' ||
ISWORDPART(*(reginput - 1)) || !ISWORDPART(*reginput))
return (0);
break;
case WORDEND:
if (*reginput == '\0')
break;
if (reginput == regbol ||
!ISWORDPART(*(reginput - 1)) || ISWORDPART(*reginput))
return (0);
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 const 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);
}
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:{
register int no;
register const 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);
}
break;
case BRANCH:{
register const 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;
case STAR:
case PLUS:{
register char nextch;
register int no;
register const 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);
}
break;
case END:
return (1); /* Success! */
break;
default:
regerror("memory corruption\n");
return (0);
break;
}
scan = nxt;
}
/*
* We get here only if there's trouble -- normally "case END" is the
* terminating point.
*/
regerror("corrupted pointers\n");
return (0);
}
/*
- regrepeat - repeatedly match something simple, report how many
*/
static int regrepeat P1(char *, p)
{
register int count = 0;
register const 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\n");
count = 0; /* Best compromise. */
break;
}
reginput = scan;
return (count);
}
/*
- regnext - dig the "nxt" pointer out of a node
*/
static char *regnext P1(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
STATIC char *regprop PROT((char *));
/*
- regdump - dump a regexp onto stdout in vaguely comprehensible form
*/
void regdump P1(regexp *, r)
{
register char *s;
register char op = EXACTLY; /* Arbitrary non-END op. */
register char *nxt;
#ifdef _AIX
extern char *strchr();
#endif /* _AIX */
s = r->program + 1;
while (op != END) { /* While that wasn't END last time... */
op = OP(s);
printf("%2d%s", (int) (s - r->program), regprop(s)); /* Where, what. */
nxt = regnext(s);
if (nxt == (char *) NULL) /* nxt ptr. */
printf("(0)");
else
printf("(%d)", (int) ((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 P1(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 WORDSTART:
p = "WORDSTART";
break;
case WORDEND:
p = "WORDEND";
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;
case PLUS:
p = "PLUS";
break;
default:
regerror("corrupted opcode\n");
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 int strcspn P2(char *, s1, char *, s2)
{
register char *scan1;
register char *scan2;
register int count;
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
*/
char *regsub P4(regexp *, prog, char *, source, char *, dest, int, n)
{
register char *src;
register char *dst;
register char c;
register int no;
register int len;
if (prog == (regexp *) NULL ||
source == (char *) NULL || dest == (char *) NULL) {
regerror("NULL parm to regsub\n");
return NULL;
}
if (UCHARAT(prog->program) != MAGIC) {
regerror("damaged regexp fed to regsub\n");
return NULL;
}
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++;
if (--n < 0) { /* amylaar */
regerror("line too long\n");
return NULL;
}
*dst++ = c;
} else if (prog->startp[no] != (char *) NULL &&
prog->endp[no] != (char *) NULL) {
len = prog->endp[no] - prog->startp[no];
if ((n -= len) < 0) { /* amylaar */
regerror("line too long\n");
return NULL;
}
strncpy(dst, prog->startp[no], len);
dst += len;
if (len != 0 && *(dst - 1) == '\0') { /* strncpy hit NUL. */
regerror("damaged match string\n");
return NULL;
}
}
}
if (--n < 0) { /* amylaar */
regerror("line too long\n");
return NULL;
}
*dst = '\0';
return dst;
}
