1/*
 2 * Copyright (c) 2002 J. Mallett.  All rights reserved.
 3 * You may do whatever you want with this file as long as
 4 * the above copyright and this notice remain intact, along
 5 * with the following statement:
 6 * 	For the man who taught me vi, and who got too old, too young.
 7 */
 8
 9#include <stdio.h>
10#include <stdlib.h>
11#include <string.h>
12
13#include "../util.h"
14
15/*
16 * Replaces str with a string consisting of str with match replaced with
17 * replstr as many times as can be done before the constructed string is
18 * maxsize bytes large.  It does not free the string pointed to by str, it
19 * is up to the calling program to be sure that the original contents of
20 * str as well as the new contents are handled in an appropriate manner.
21 * If replstr is NULL, then that internally is changed to a nil-string, so
22 * that we can still pretend to do somewhat meaningful substitution.
23 * No value is returned.
24 */
25void
26strnsubst(char **str, const char *match, const char *replstr, size_t maxsize)
27{
28  char  *s1, *s2, *this;
29  size_t matchlen, s2len;
30  int    n;
31
32  if ((s1 = *str) == NULL)
33    return;
34  s2 = emalloc(maxsize);
35
36  if (replstr == NULL)
37    replstr = "";
38
39  if (match == NULL || *match == '\0' || strlen(s1) >= maxsize) {
40    strlcpy(s2, s1, maxsize);
41    goto done;
42  }
43
44  *s2      = '\0';
45  s2len    = 0;
46  matchlen = strlen(match);
47  for (;;) {
48    if ((this = strstr(s1, match)) == NULL)
49      break;
50    n = snprintf(s2 + s2len, maxsize - s2len, "%.*s%s", (int)(this - s1), s1, replstr);
51    if (n == -1 || n + s2len + strlen(this + matchlen) >= maxsize)
52      break; /* out of room */
53    s2len += n;
54    s1 = this + matchlen;
55  }
56  strlcpy(s2 + s2len, s1, maxsize - s2len);
57done:
58  *str = s2;
59  return;
60}