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regsub.c
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regsub.c
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/*
* regsub
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <ctype.h>
#include <regexp.h>
#include "regmagic.h"
/*
- regsub - perform substitutions after a regexp match
*/
void
regsub(rp, source, dest)
const regexp *rp;
const char *source;
char *dest;
{
register regexp * const prog = (regexp *)rp;
register char *src = (char *)source;
register char *dst = dest;
register char c;
register int no;
register size_t len;
if (prog == NULL || source == NULL || dest == NULL) {
regerror("NULL parameter to regsub");
return;
}
if ((unsigned char)*(prog->program) != MAGIC) {
regerror("damaged regexp");
return;
}
while ((c = *src++) != '\0') {
if (c == '&')
no = 0;
else if (c == '\\' && isdigit(*src))
no = *src++ - '0';
else
no = -1;
if (no < 0) { /* Ordinary character. */
if (c == '\\' && (*src == '\\' || *src == '&'))
c = *src++;
*dst++ = c;
} else if (prog->startp[no] != NULL && prog->endp[no] != NULL &&
prog->endp[no] > prog->startp[no]) {
len = prog->endp[no] - prog->startp[no];
(void) strncpy(dst, prog->startp[no], len);
dst += len;
if (*(dst-1) == '\0') { /* strncpy hit NUL. */
regerror("damaged match string");
return;
}
}
}
*dst++ = '\0';
}