1 /* $OpenBSD: __mktemp4.c,v 1.1 2024/01/19 19:45:02 millert Exp $ */ 2 /* 3 * Copyright (c) 1996-1998, 2008 Theo de Raadt 4 * Copyright (c) 1997, 2008-2009, 2024 Todd C. Miller 5 * 6 * Permission to use, copy, modify, and distribute this software for any 7 * purpose with or without fee is hereby granted, provided that the above 8 * copyright notice and this permission notice appear in all copies. 9 * 10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17 */ 18 19 #include <errno.h> 20 #include <limits.h> 21 #include <stdlib.h> 22 #include <string.h> 23 24 #define TEMPCHARS "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789" 25 #define NUM_CHARS (sizeof(TEMPCHARS) - 1) 26 #define MIN_X 6 27 28 #ifndef nitems 29 #define nitems(_a) (sizeof((_a)) / sizeof((_a)[0])) 30 #endif 31 32 /* 33 * Internal driver for the mktemp(3) family of functions. 34 * The supplied callback does the actual work of testing or 35 * creating the file/directory. 36 */ 37 int 38 __mktemp4(char *path, int slen, int flags, int (*cb)(const char *, int)) 39 { 40 char *start, *cp, *ep; 41 const char tempchars[] = TEMPCHARS; 42 unsigned int tries; 43 size_t len; 44 int ret; 45 46 len = strlen(path); 47 if (len < MIN_X || slen < 0 || (size_t)slen > len - MIN_X) { 48 errno = EINVAL; 49 return -1; 50 } 51 ep = path + len - slen; 52 53 for (start = ep; start > path && start[-1] == 'X'; start--) 54 ; 55 if (ep - start < MIN_X) { 56 errno = EINVAL; 57 return -1; 58 } 59 60 tries = INT_MAX; 61 do { 62 cp = start; 63 do { 64 unsigned short rbuf[16]; 65 unsigned int i; 66 67 /* 68 * Avoid lots of arc4random() calls by using 69 * a buffer sized for up to 16 Xs at a time. 70 */ 71 arc4random_buf(rbuf, sizeof(rbuf)); 72 for (i = 0; i < nitems(rbuf) && cp != ep; i++) 73 *cp++ = tempchars[rbuf[i] % NUM_CHARS]; 74 } while (cp != ep); 75 76 ret = cb(path, flags); 77 if (ret != -1 || errno != EEXIST) 78 return ret; 79 } while (--tries); 80 81 errno = EEXIST; 82 return -1; 83 } 84