/* $Id$ */
/* $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 "config.h"
#include <sys/types.h>
#include <errno.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.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))
/*
* Even though specified in POSIX, the PAGESIZE and PAGE_SIZE
* macros have very poor portability. Since we only use this
* to avoid free() overhead for small shrinking, simply pick
* an arbitrary number.
*/
#define getpagesize() (1UL << 12)
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 < 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);
/*
* At this point, the OpenBSD implementation calls
* explicit_bzero() on the old memory before it is
* freed. Since explicit_bzero() is hard to implement
* portably and we don't handle confidential data in
* mandoc in the first place, simply free the memory
* without clearing it.
*/
free(ptr);
return newptr;
}
