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Annotation of embedaddon/tmux/compat/recallocarray.c, revision 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: }