1 /* $NetBSD: expandm.c,v 1.13 2024/10/04 08:37:20 rillig Exp $ */ 2 3 /*- 4 * Copyright (c) 2019 The NetBSD Foundation, Inc. 5 * All rights reserved. 6 * 7 * This code is derived from software contributed to The NetBSD Foundation 8 * by Christos Zoulas. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 29 * POSSIBILITY OF SUCH DAMAGE. 30 */ 31 #include <sys/cdefs.h> 32 __RCSID("$NetBSD: expandm.c,v 1.13 2024/10/04 08:37:20 rillig Exp $"); 33 34 #include <limits.h> 35 #include <stdio.h> 36 #include <string.h> 37 #include <stdlib.h> 38 #include <errno.h> 39 40 #include "expandm.h" 41 42 #ifdef TEST 43 #undef INT_MAX 44 #define INT_MAX 31 45 #endif 46 47 48 const char * __attribute__((__format_arg__(1))) 49 expandm(const char *fmt, const char *sf, char **rbuf) 50 { 51 const int err = errno; 52 const char *e = NULL; 53 char *buf, *nbuf; 54 const char *ptr, *m; 55 56 buf = NULL; 57 for (ptr = fmt; (m = strstr(ptr, "%m")) != NULL; ptr = m + 2) { 58 size_t cnt = 0; 59 size_t nlen; 60 61 for (const char *p = m; p >= ptr && *p == '%'; p--) 62 cnt++; 63 64 nlen = (size_t)(m - ptr); 65 /* 66 * we can't exceed INT_MAX because int is used as 67 * a format width 68 */ 69 if (__predict_false(nlen >= INT_MAX)) { 70 size_t blen = buf ? strlen(buf) : 0; 71 size_t tlen; 72 73 /* 74 * if we would overflow a ptrdiff_t when computing 75 * tlen, then don't bother. The format string is 76 * simply too large to be converted. 77 */ 78 if (blen >= PTRDIFF_MAX || 79 nlen >= PTRDIFF_MAX - blen || 80 nlen >= SIZE_T_MAX - blen) 81 goto out; 82 83 tlen = nlen + blen; 84 85 nbuf = realloc(buf, tlen + 1); 86 if (nbuf == NULL) 87 goto out; 88 89 memcpy(nbuf + blen, ptr, nlen); 90 nbuf[tlen] = '\0'; 91 ptr += nlen; 92 buf = nbuf; 93 } 94 95 if (__predict_true(e == NULL && (cnt & 1) != 0)) 96 e = strerror(err); 97 if (asprintf(&nbuf, "%s%.*s%s", buf ? buf : "", 98 (int)(m - ptr), ptr, (cnt & 1) ? e : "%m") == -1) 99 goto out; 100 free(buf); 101 buf = nbuf; 102 } 103 104 if (asprintf(&nbuf, "%s%s%s", buf ? buf : "", ptr, sf ? sf : "") == -1) 105 goto out; 106 107 free(buf); 108 if (rbuf) 109 *rbuf = nbuf; 110 errno = err; 111 return nbuf; 112 out: 113 free(buf); 114 if (rbuf) 115 *rbuf = NULL; 116 errno = err; 117 return fmt; 118 } 119 120 #ifdef TEST 121 int 122 main(int argc, char *argv[]) 123 { 124 errno = ERANGE; 125 printf("%s\n", expandm(argc > 1 ? argv[1] : "Message %%m=%m: %%%m%%", 126 "...", NULL)); 127 return 0; 128 } 129 #endif 130