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/* $OpenBSD: strnsubst.c,v 1.5 2009/10/27 23:59:50 deraadt Exp $ */ |
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/* $FreeBSD: strnsubst.c,v 1.6 2002/06/22 12:58:42 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 <err.h> |
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#include <stdio.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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* If replstr is NULL, then that internally is changed to a nil-string, so |
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* that we can still pretend to do somewhat meaningful substitution. |
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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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size_t matchlen, repllen, s2len; |
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int n; |
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if ((s1 = *str) == NULL) |
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return; |
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if ((s2 = malloc(maxsize)) == NULL) |
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err(1, NULL); |
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if (replstr == NULL) |
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replstr = ""; |
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if (match == NULL || *match == '\0' || strlen(s1) >= maxsize) { |
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strlcpy(s2, s1, maxsize); |
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goto done; |
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} |
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*s2 = '\0'; |
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s2len = 0; |
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matchlen = strlen(match); |
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repllen = strlen(replstr); |
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for (;;) { |
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if ((this = strstr(s1, match)) == NULL) |
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break; |
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n = snprintf(s2 + s2len, maxsize - s2len, "%.*s%s", |
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(int)(this - s1), s1, replstr); |
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if (n == -1 || n + s2len + strlen(this + matchlen) >= maxsize) |
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break; /* out of room */ |
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s2len += n; |
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s1 = this + matchlen; |
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} |
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strlcpy(s2 + s2len, s1, maxsize - s2len); |
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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, *z, *za; |
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x = "{}%$"; |
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strnsubst(&x, "%$", "{} enpury!", 255); |
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y = x; |
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strnsubst(&y, "}{}", "ybir", 255); |
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z = y; |
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strnsubst(&z, "{", "v ", 255); |
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za = z; |
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strnsubst(&z, NULL, za, 255); |
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if (strcmp(z, "v ybir enpury!") == 0) |
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printf("strnsubst() seems to work!\n"); |
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else |
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printf("strnsubst() is broken.\n"); |
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printf("%s\n", z); |
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free(x); |
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free(y); |
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free(z); |
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free(za); |
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return 0; |
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} |
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#endif |