1 /* $Id: compat_recallocarray.c,v 1.2 2020/06/15 01:37:15 schwarze Exp $ */ 2 /* $OpenBSD: recallocarray.c,v 1.1 2017/03/06 18:44:21 otto Exp $ */ 3 /* 4 * Copyright (c) 2008, 2017 Otto Moerbeek <otto@drijf.net> 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 #include "config.h" 19 20 #include <sys/types.h> 21 #include <errno.h> 22 #include <stdlib.h> 23 #include <stdint.h> 24 #include <string.h> 25 26 /* 27 * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX 28 * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW 29 */ 30 #define MUL_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4)) 31 32 /* 33 * Even though specified in POSIX, the PAGESIZE and PAGE_SIZE 34 * macros have very poor portability. Since we only use this 35 * to avoid free() overhead for small shrinking, simply pick 36 * an arbitrary number. 37 */ 38 #define getpagesize() (1UL << 12) 39 40 41 void * 42 recallocarray(void *ptr, size_t oldnmemb, size_t newnmemb, size_t size) 43 { 44 size_t oldsize, newsize; 45 void *newptr; 46 47 if (ptr == NULL) 48 return calloc(newnmemb, size); 49 50 if ((newnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) && 51 newnmemb > 0 && SIZE_MAX / newnmemb < size) { 52 errno = ENOMEM; 53 return NULL; 54 } 55 newsize = newnmemb * size; 56 57 if ((oldnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) && 58 oldnmemb > 0 && SIZE_MAX / oldnmemb < size) { 59 errno = EINVAL; 60 return NULL; 61 } 62 oldsize = oldnmemb * size; 63 64 /* 65 * Don't bother too much if we're shrinking just a bit, 66 * we do not shrink for series of small steps, oh well. 67 */ 68 if (newsize <= oldsize) { 69 size_t d = oldsize - newsize; 70 71 if (d < oldsize / 2 && d < getpagesize()) { 72 memset((char *)ptr + newsize, 0, d); 73 return ptr; 74 } 75 } 76 77 newptr = malloc(newsize); 78 if (newptr == NULL) 79 return NULL; 80 81 if (newsize > oldsize) { 82 memcpy(newptr, ptr, oldsize); 83 memset((char *)newptr + oldsize, 0, newsize - oldsize); 84 } else 85 memcpy(newptr, ptr, newsize); 86 87 /* 88 * At this point, the OpenBSD implementation calls 89 * explicit_bzero() on the old memory before it is 90 * freed. Since explicit_bzero() is hard to implement 91 * portably and we don't handle confidential data in 92 * mandoc in the first place, simply free the memory 93 * without clearing it. 94 */ 95 96 free(ptr); 97 98 return newptr; 99 } 100