diff options
Diffstat (limited to 'compat/recallocarray.c')
-rw-r--r-- | compat/recallocarray.c | 82 |
1 files changed, 82 insertions, 0 deletions
diff --git a/compat/recallocarray.c b/compat/recallocarray.c new file mode 100644 index 0000000..74a919a --- /dev/null +++ b/compat/recallocarray.c @@ -0,0 +1,82 @@ +/* $OpenBSD: recallocarray.c,v 1.1 2017/03/06 18:44:21 otto Exp $ */ +/* + * Copyright (c) 2008, 2017 Otto Moerbeek <otto@drijf.net> + * + * Permission to use, copy, modify, and distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES + * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF + * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR + * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES + * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN + * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF + * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. + */ + +#include <errno.h> +#include <stdlib.h> +#include <stdint.h> +#include <string.h> +#include <unistd.h> + +#include "compat.h" + +/* + * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX + * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW + */ +#define MUL_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4)) + +void * +recallocarray(void *ptr, size_t oldnmemb, size_t newnmemb, size_t size) +{ + size_t oldsize, newsize; + void *newptr; + + if (ptr == NULL) + return calloc(newnmemb, size); + + if ((newnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) && + newnmemb > 0 && SIZE_MAX / newnmemb < size) { + errno = ENOMEM; + return NULL; + } + newsize = newnmemb * size; + + if ((oldnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) && + oldnmemb > 0 && SIZE_MAX / oldnmemb < size) { + errno = EINVAL; + return NULL; + } + oldsize = oldnmemb * size; + + /* + * Don't bother too much if we're shrinking just a bit, + * we do not shrink for series of small steps, oh well. + */ + if (newsize <= oldsize) { + size_t d = oldsize - newsize; + + if (d < oldsize / 2 && d < (size_t)getpagesize()) { + memset((char *)ptr + newsize, 0, d); + return ptr; + } + } + + newptr = malloc(newsize); + if (newptr == NULL) + return NULL; + + if (newsize > oldsize) { + memcpy(newptr, ptr, oldsize); + memset((char *)newptr + oldsize, 0, newsize - oldsize); + } else + memcpy(newptr, ptr, newsize); + + explicit_bzero(ptr, oldsize); + free(ptr); + + return newptr; +} |