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38dff9a439
s1 was 0 length, and replstr was 0 length, etc., we would end up subtracting one from zero and seeing if it was greater than the size_t (unsigned) var maxsize... This would cause us to return a string consisting of essentially only match, which is not the right behaviour if we have 0 length inpline.
82 lines
1.9 KiB
C
82 lines
1.9 KiB
C
/* $xMach: strnsubst.c,v 1.3 2002/02/23 02:10:24 jmallett Exp $ */
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/*
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* Copyright (c) 2002 J. Mallett. All rights reserved.
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* You may do whatever you want with this file as long as
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* the above copyright and this notice remain intact, along
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* with the following statement:
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* For the man who taught me vi, and who got too old, too young.
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include <err.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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void strnsubst(char **, const char *, const char *, size_t);
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/*
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* Replaces str with a string consisting of str with match replaced with
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* replstr as many times as can be done before the constructed string is
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* maxsize bytes large. It does not free the string pointed to by str, it
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* is up to the calling program to be sure that the original contents of
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* str as well as the new contents are handled in an appropriate manner.
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* No value is returned.
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*/
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void
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strnsubst(char **str, const char *match, const char *replstr, size_t maxsize)
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{
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char *s1, *s2, *this;
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s1 = *str;
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if (s1 == NULL)
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return;
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s2 = calloc(maxsize, 1);
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if (s2 == NULL)
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err(1, "calloc");
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if (match == NULL || replstr == NULL || maxsize == strlen(s1)) {
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strlcpy(s2, s1, maxsize);
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goto done;
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}
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for (;;) {
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this = strstr(s1, match);
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if (this == NULL)
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break;
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if ((strlen(s2) + ((uintptr_t)this - (uintptr_t)s1) +
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(strlen(replstr) - 1)) > maxsize && *replstr != '\0') {
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strlcat(s2, s1, maxsize);
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goto done;
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}
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strncat(s2, s1, (uintptr_t)this - (uintptr_t)s1);
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strcat(s2, replstr);
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s1 = this + strlen(match);
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}
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strcat(s2, s1);
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done:
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*str = s2;
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return;
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}
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#ifdef TEST
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#include <stdio.h>
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int
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main(void)
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{
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char *x, *y;
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y = x = "{}{}{}";
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strnsubst(&x, "{}", "v ybir whyv! ", 12);
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if (strcmp(x, "v ybir whyv! ") == 0)
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printf("strnsubst() seems to work as expected.\n");
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printf("x: %s\ny: %s\n", x, y);
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free(x);
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return 0;
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}
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#endif
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