Annotation of mandoc/compat_recallocarray.c, Revision 1.1
1.1 ! schwarze 1: #include "config.h"
! 2:
! 3: #if HAVE_RECALLOCARRAY
! 4:
! 5: int dummy;
! 6:
! 7: #else
! 8:
! 9: /* $Id: compat_reallocarray.c,v 1.4 2014/12/11 09:05:01 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 */
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