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/* $xMach: strnsubst.c,v 1.3 2002/02/23 02:10:24 jmallett Exp $ */
/*
* Copyright (c) 2002 J. Mallett. All rights reserved.
* You may do whatever you want with this file as long as
* the above copyright and this notice remain intact, along
* with the following statement:
* For the man who taught me vi, and who got too old, too young.
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <err.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
void strnsubst(char **, const char *, const char *, size_t);
/*
* Replaces str with a string consisting of str with match replaced with
* replstr as many times as can be done before the constructed string is
* maxsize bytes large. It does not free the string pointed to by str, it
* is up to the calling program to be sure that the original contents of
* str as well as the new contents are handled in an appropriate manner.
* If replstr is NULL, then that internally is changed to a nil-string, so
* that we can still pretend to do somewhat meaningful substitution.
* No value is returned.
*/
void
strnsubst(char **str, const char *match, const char *replstr, size_t maxsize)
{
char *s1, *s2, *this;
s1 = *str;
if (s1 == NULL)
return;
s2 = calloc(maxsize, 1);
if (s2 == NULL)
err(1, "calloc");
if (replstr == NULL)
replstr = "";
if (match == NULL || replstr == NULL || maxsize == strlen(s1)) {
strlcpy(s2, s1, maxsize);
goto done;
}
for (;;) {
this = strstr(s1, match);
if (this == NULL)
break;
if ((strlen(s2) + ((uintptr_t)this - (uintptr_t)s1) +
(strlen(replstr) - 1)) > maxsize && *replstr != '\0') {
strlcat(s2, s1, maxsize);
goto done;
}
strncat(s2, s1, (uintptr_t)this - (uintptr_t)s1);
strcat(s2, replstr);
s1 = this + strlen(match);
}
strcat(s2, s1);
done:
*str = s2;
return;
}
#ifdef TEST
#include <stdio.h>
int
main(void)
{
char *x, *y;
y = x = "{}{}{}";
strnsubst(&x, "{}", "v ybir whyv! ", 12);
if (strcmp(x, "v ybir whyv! ") == 0)
printf("strnsubst() seems to work as expected.\n");
printf("x: %s\ny: %s\n", x, y);
free(x);
return 0;
}
#endif
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