100 lines
2.8 KiB
C
100 lines
2.8 KiB
C
/* $Id: compat_recallocarray.c,v 1.2 2020/06/15 01:37:15 schwarze Exp $ */
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/* $OpenBSD: recallocarray.c,v 1.1 2017/03/06 18:44:21 otto Exp $ */
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/*
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* Copyright (c) 2008, 2017 Otto Moerbeek <otto@drijf.net>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include "config.h"
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#include <sys/types.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <stdint.h>
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#include <string.h>
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/*
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* This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
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* if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
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*/
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#define MUL_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4))
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/*
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* Even though specified in POSIX, the PAGESIZE and PAGE_SIZE
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* macros have very poor portability. Since we only use this
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* to avoid free() overhead for small shrinking, simply pick
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* an arbitrary number.
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*/
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#define getpagesize() (1UL << 12)
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void *
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recallocarray(void *ptr, size_t oldnmemb, size_t newnmemb, size_t size)
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{
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size_t oldsize, newsize;
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void *newptr;
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if (ptr == NULL)
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return calloc(newnmemb, size);
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if ((newnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
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newnmemb > 0 && SIZE_MAX / newnmemb < size) {
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errno = ENOMEM;
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return NULL;
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}
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newsize = newnmemb * size;
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if ((oldnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
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oldnmemb > 0 && SIZE_MAX / oldnmemb < size) {
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errno = EINVAL;
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return NULL;
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}
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oldsize = oldnmemb * size;
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/*
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* Don't bother too much if we're shrinking just a bit,
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* we do not shrink for series of small steps, oh well.
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*/
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if (newsize <= oldsize) {
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size_t d = oldsize - newsize;
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if (d < oldsize / 2 && d < getpagesize()) {
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memset((char *)ptr + newsize, 0, d);
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return ptr;
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}
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}
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newptr = malloc(newsize);
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if (newptr == NULL)
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return NULL;
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if (newsize > oldsize) {
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memcpy(newptr, ptr, oldsize);
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memset((char *)newptr + oldsize, 0, newsize - oldsize);
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} else
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memcpy(newptr, ptr, newsize);
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/*
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* At this point, the OpenBSD implementation calls
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* explicit_bzero() on the old memory before it is
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* freed. Since explicit_bzero() is hard to implement
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* portably and we don't handle confidential data in
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* mandoc in the first place, simply free the memory
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* without clearing it.
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*/
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free(ptr);
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return newptr;
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}
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