1 /* $OpenBSD: recallocarray.c,v 1.1 2017/03/06 18:44:21 otto Exp $ */ 2 /* 3 * Copyright (c) 2008, 2017 Otto Moerbeek <otto@drijf.net> 4 * 5 * Permission to use, copy, modify, and distribute this software for any 6 * purpose with or without fee is hereby granted, provided that the above 7 * copyright notice and this permission notice appear in all copies. 8 * 9 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 10 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 11 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 12 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 13 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 14 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 15 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 16 */ 17 18 #include <errno.h> 19 #include <stdlib.h> 20 #include <stdint.h> 21 #include <string.h> 22 #include <unistd.h> 23 24 /* 25 * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX 26 * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW 27 */ 28 #define MUL_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4)) 29 30 void * 31 recallocarray(void *ptr, size_t oldnmemb, size_t newnmemb, size_t size) 32 { 33 size_t oldsize, newsize; 34 void *newptr; 35 36 if (ptr == NULL) 37 return calloc(newnmemb, size); 38 39 if ((newnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) && 40 newnmemb > 0 && SIZE_MAX / newnmemb < size) { 41 errno = ENOMEM; 42 return NULL; 43 } 44 newsize = newnmemb * size; 45 46 if ((oldnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) && 47 oldnmemb > 0 && SIZE_MAX / oldnmemb < size) { 48 errno = EINVAL; 49 return NULL; 50 } 51 oldsize = oldnmemb * size; 52 53 /* 54 * Don't bother too much if we're shrinking just a bit, 55 * we do not shrink for series of small steps, oh well. 56 */ 57 if (newsize <= oldsize) { 58 size_t d = oldsize - newsize; 59 60 if (d < oldsize / 2 && d < getpagesize()) { 61 memset((char *)ptr + newsize, 0, d); 62 return ptr; 63 } 64 } 65 66 newptr = malloc(newsize); 67 if (newptr == NULL) 68 return NULL; 69 70 if (newsize > oldsize) { 71 memcpy(newptr, ptr, oldsize); 72 memset((char *)newptr + oldsize, 0, newsize - oldsize); 73 } else 74 memcpy(newptr, ptr, newsize); 75 76 explicit_bzero(ptr, oldsize); 77 free(ptr); 78 79 return newptr; 80 } 81