1 /* $OpenBSD: strnsubst.c,v 1.2 2003/06/12 03:23:22 millert Exp $ */ 2 /* $FreeBSD: strnsubst.c,v 1.6 2002/06/22 12:58:42 jmallett Exp $ */ 3 4 /* 5 * Copyright (c) 2002 J. Mallett. All rights reserved. 6 * You may do whatever you want with this file as long as 7 * the above copyright and this notice remain intact, along 8 * with the following statement: 9 * For the man who taught me vi, and who got too old, too young. 10 */ 11 12 #ifndef lint 13 static const char rcsid[] = "$OpenBSD: strnsubst.c,v 1.2 2003/06/12 03:23:22 millert Exp $"; 14 #endif /* not lint */ 15 16 #include <err.h> 17 #include <stdio.h> 18 #include <stdlib.h> 19 #include <string.h> 20 #include <unistd.h> 21 22 void strnsubst(char **, const char *, const char *, size_t); 23 24 /* 25 * Replaces str with a string consisting of str with match replaced with 26 * replstr as many times as can be done before the constructed string is 27 * maxsize bytes large. It does not free the string pointed to by str, it 28 * is up to the calling program to be sure that the original contents of 29 * str as well as the new contents are handled in an appropriate manner. 30 * If replstr is NULL, then that internally is changed to a nil-string, so 31 * that we can still pretend to do somewhat meaningful substitution. 32 * No value is returned. 33 */ 34 void 35 strnsubst(char **str, const char *match, const char *replstr, size_t maxsize) 36 { 37 char *s1, *s2, *this; 38 size_t matchlen, repllen, s2len, n; 39 40 if ((s1 = *str) == NULL) 41 return; 42 if ((s2 = malloc(maxsize)) == NULL) 43 err(1, NULL); 44 45 if (replstr == NULL) 46 replstr = ""; 47 48 if (match == NULL || *match == '\0' || strlen(s1) >= maxsize) { 49 strlcpy(s2, s1, maxsize); 50 goto done; 51 } 52 53 *s2 = '\0'; 54 s2len = 0; 55 matchlen = strlen(match); 56 repllen = strlen(replstr); 57 for (;;) { 58 if ((this = strstr(s1, match)) == NULL) 59 break; 60 n = snprintf(s2 + s2len, maxsize - s2len, "%.*s%s", 61 (int)(this - s1), s1, replstr); 62 if (n == -1 || n + s2len + strlen(this + matchlen) >= maxsize) 63 break; /* out of room */ 64 s2len += n; 65 s1 = this + matchlen; 66 } 67 strlcpy(s2 + s2len, s1, maxsize - s2len); 68 done: 69 *str = s2; 70 return; 71 } 72 73 #ifdef TEST 74 #include <stdio.h> 75 76 int 77 main(void) 78 { 79 char *x, *y, *z, *za; 80 81 x = "{}%$"; 82 strnsubst(&x, "%$", "{} enpury!", 255); 83 y = x; 84 strnsubst(&y, "}{}", "ybir", 255); 85 z = y; 86 strnsubst(&z, "{", "v ", 255); 87 za = z; 88 strnsubst(&z, NULL, za, 255); 89 if (strcmp(z, "v ybir enpury!") == 0) 90 printf("strnsubst() seems to work!\n"); 91 else 92 printf("strnsubst() is broken.\n"); 93 printf("%s\n", z); 94 free(x); 95 free(y); 96 free(z); 97 free(za); 98 return 0; 99 } 100 #endif 101