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Annotation of embedaddon/tmux/compat/recallocarray.c, revision 1.1.1.1

1.1       misho       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: #include "compat.h"
                     25: 
                     26: /*
                     27:  * This is sqrt(SIZE_MAX+1), as s1*s2 <= SIZE_MAX
                     28:  * if both s1 < MUL_NO_OVERFLOW and s2 < MUL_NO_OVERFLOW
                     29:  */
                     30: #define MUL_NO_OVERFLOW ((size_t)1 << (sizeof(size_t) * 4))
                     31: 
                     32: void *
                     33: recallocarray(void *ptr, size_t oldnmemb, size_t newnmemb, size_t size)
                     34: {
                     35:        size_t oldsize, newsize;
                     36:        void *newptr;
                     37: 
                     38:        if (ptr == NULL)
                     39:                return calloc(newnmemb, size);
                     40: 
                     41:        if ((newnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
                     42:            newnmemb > 0 && SIZE_MAX / newnmemb < size) {
                     43:                errno = ENOMEM;
                     44:                return NULL;
                     45:        }
                     46:        newsize = newnmemb * size;
                     47: 
                     48:        if ((oldnmemb >= MUL_NO_OVERFLOW || size >= MUL_NO_OVERFLOW) &&
                     49:            oldnmemb > 0 && SIZE_MAX / oldnmemb < size) {
                     50:                errno = EINVAL;
                     51:                return NULL;
                     52:        }
                     53:        oldsize = oldnmemb * size;
                     54: 
                     55:        /*
                     56:         * Don't bother too much if we're shrinking just a bit,
                     57:         * we do not shrink for series of small steps, oh well.
                     58:         */
                     59:        if (newsize <= oldsize) {
                     60:                size_t d = oldsize - newsize;
                     61: 
                     62:                if (d < oldsize / 2 && d < (size_t)getpagesize()) {
                     63:                        memset((char *)ptr + newsize, 0, d);
                     64:                        return ptr;
                     65:                }
                     66:        }
                     67: 
                     68:        newptr = malloc(newsize);
                     69:        if (newptr == NULL)
                     70:                return NULL;
                     71: 
                     72:        if (newsize > oldsize) {
                     73:                memcpy(newptr, ptr, oldsize);
                     74:                memset((char *)newptr + oldsize, 0, newsize - oldsize);
                     75:        } else
                     76:                memcpy(newptr, ptr, newsize);
                     77: 
                     78:        explicit_bzero(ptr, oldsize);
                     79:        free(ptr);
                     80: 
                     81:        return newptr;
                     82: }