1/* $xMach: strnsubst.c,v 1.3 2002/02/23 02:10:24 jmallett Exp $ */ 2 3/* 4 * Copyright (c) 2002 J. Mallett. All rights reserved. 5 * You may do whatever you want with this file as long as 6 * the above copyright and this notice remain intact, along 7 * with the following statement: 8 * For the man who taught me vi, and who got too old, too young. 9 */ 10 11#include <sys/cdefs.h> 12#ifndef lint 13#if 0 14__FBSDID("$FreeBSD: src/usr.bin/xargs/strnsubst.c,v 1.8 2005/12/30 23:22:50 jmallett Exp $"); 15#endif 16__RCSID("$NetBSD$"); 17#endif /* not lint */ 18 19#include <err.h> 20#include <stdlib.h> 21#include <string.h> 22#include <unistd.h> 23#include <stdint.h> 24 25void strnsubst(char **, const char *, const char *, size_t); 26 27/* 28 * Replaces str with a string consisting of str with match replaced with 29 * replstr as many times as can be done before the constructed string is 30 * maxsize bytes large. It does not free the string pointed to by str, it 31 * is up to the calling program to be sure that the original contents of 32 * str as well as the new contents are handled in an appropriate manner. 33 * If replstr is NULL, then that internally is changed to a nil-string, so 34 * that we can still pretend to do somewhat meaningful substitution. 35 * No value is returned. 36 */ 37void 38strnsubst(char **str, const char *match, const char *replstr, size_t maxsize) 39{ 40 char *s1, *s2, *this; 41 42 s1 = *str; 43 if (s1 == NULL) 44 return; 45 /* 46 * If maxsize is 0 then set it to to the length of s1, because we have 47 * to duplicate s1. XXX we maybe should double-check whether the match 48 * appears in s1. If it doesn't, then we also have to set the length 49 * to the length of s1, to avoid modifying the argument. It may make 50 * sense to check if maxsize is <= strlen(s1), because in that case we 51 * want to return the unmodified string, too. 52 */ 53 if (maxsize == 0) { 54 match = NULL; 55 maxsize = strlen(s1) + 1; 56 } 57 s2 = calloc(maxsize, 1); 58 if (s2 == NULL) 59 err(1, "calloc"); 60 61 if (replstr == NULL) 62 replstr = ""; 63 64 if (match == NULL || replstr == NULL || maxsize == strlen(s1)) { 65 (void)strlcpy(s2, s1, maxsize); 66 goto done; 67 } 68 69 for (;;) { 70 this = strstr(s1, match); 71 if (this == NULL) 72 break; 73 if ((strlen(s2) + strlen(s1) + strlen(replstr) - 74 strlen(match) + 1) > maxsize) { 75 (void)strlcat(s2, s1, maxsize); 76 goto done; 77 } 78 (void)strncat(s2, s1, (uintptr_t)this - (uintptr_t)s1); 79 (void)strcat(s2, replstr); 80 s1 = this + strlen(match); 81 } 82 (void)strcat(s2, s1); 83done: 84 *str = s2; 85 return; 86} 87 88#ifdef TEST 89#include <stdio.h> 90 91int 92main(void) 93{ 94 char *x, *y, *z, *za; 95 96 x = "{}%$"; 97 strnsubst(&x, "%$", "{} enpury!", 255); 98 y = x; 99 strnsubst(&y, "}{}", "ybir", 255); 100 z = y; 101 strnsubst(&z, "{", "v ", 255); 102 za = z; 103 strnsubst(&z, NULL, za, 255); 104 if (strcmp(z, "v ybir enpury!") == 0) 105 (void)printf("strnsubst() seems to work!\n"); 106 else 107 (void)printf("strnsubst() is broken.\n"); 108 (void)printf("%s\n", z); 109 free(x); 110 free(y); 111 free(z); 112 free(za); 113 return 0; 114} 115#endif 116