1 #include "config.h" 2 3 #if HAVE_RECALLOCARRAY 4 5 int dummy; 6 7 #else 8 9 /* $Id: compat_recallocarray.c,v 1.1 2017/06/12 19:05:47 schwarze Exp $ */ 10 /* $OpenBSD: malloc.c,v 1.225 2017/05/13 07:11:29 otto Exp $ */ 11 /* 12 * Copyright (c) 2017 Otto Moerbeek <otto@drijf.net> 13 * 14 * Permission to use, copy, modify, and distribute this software for any 15 * purpose with or without fee is hereby granted, provided that the above 16 * copyright notice and this permission notice appear in all copies. 17 * 18 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 19 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 20 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 21 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 22 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 23 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 24 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 25 */ 26 27 #include <sys/types.h> 28 #include <errno.h> 29 #include <stdint.h> 30 #include <stdlib.h> 31 #include <string.h> 32 33 /* 34 * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX 35 * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW 36 */ 37 #define MUL_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4)) 38 39 /* 40 * Even though specified in POSIX, the PAGESIZE and PAGE_SIZE 41 * macros have very poor portability. Since we only use this 42 * to avoid free() overhead for small shrinking, simply pick 43 * an arbitrary number. 44 */ 45 #define MALLOC_PAGESIZE (1UL << 12) 46 47 48 void * 49 recallocarray(void *ptr, size_t oldnmemb, size_t newnmemb, size_t size) 50 { 51 size_t oldsize, newsize; 52 void *newptr; 53 54 if (ptr == NULL) 55 return calloc(newnmemb, size); 56 57 if ((newnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) && 58 newnmemb > 0 && SIZE_MAX / newnmemb < size) { 59 errno = ENOMEM; 60 return NULL; 61 } 62 newsize = newnmemb * size; 63 64 if ((oldnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) && 65 oldnmemb > 0 && SIZE_MAX / oldnmemb < size) { 66 errno = EINVAL; 67 return NULL; 68 } 69 oldsize = oldnmemb * size; 70 71 /* 72 * Don't bother too much if we're shrinking just a bit, 73 * we do not shrink for series of small steps, oh well. 74 */ 75 if (newsize <= oldsize) { 76 size_t d = oldsize - newsize; 77 78 if (d < oldsize / 2 && d < MALLOC_PAGESIZE) { 79 memset((char *)ptr + newsize, 0, d); 80 return ptr; 81 } 82 } 83 84 newptr = malloc(newsize); 85 if (newptr == NULL) 86 return NULL; 87 88 if (newsize > oldsize) { 89 memcpy(newptr, ptr, oldsize); 90 memset((char *)newptr + oldsize, 0, newsize - oldsize); 91 } else 92 memcpy(newptr, ptr, newsize); 93 94 /* 95 * At this point, the OpenBSD implementation calls 96 * explicit_bzero() on the old memory before it is 97 * freed. Since explicit_bzero() is hard to implement 98 * portably and we don't handle confidential data in 99 * mandoc in the first place, simply free the memory 100 * without clearing it. 101 */ 102 103 free(ptr); 104 105 return newptr; 106 } 107 108 #endif /* !HAVE_RECALLOCARRAY */ 109