usr/src/lib/libidmap/common/sized_array.c

   1 /*
   2  * CDDL HEADER START
   3  *
   4  * The contents of this file are subject to the terms of the
   5  * Common Development and Distribution License (the "License").
   6  * You may not use this file except in compliance with the License.
   7  *
   8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
   9  * or http://www.opensolaris.org/os/licensing.
  10  * See the License for the specific language governing permissions
  11  * and limitations under the License.
  12  *
  13  * When distributing Covered Code, include this CDDL HEADER in each
  14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
  18  *
  19  * CDDL HEADER END
  20  */
  21
  22 /*
  23  * Copyright 2009 Sun Microsystems, Inc.  All rights reserved.
  24  * Use is subject to license terms.
  25  */
  26
  27 /*
  28  * Much like calloc, but with functions to report the size of the
  29  * allocation given only the pointer.
  30  */
  31
  32 #include <assert.h>
  33 #include <string.h>
  34 #include <malloc.h>
  35 #include "sized_array.h"
  36
  37 /*
  38  * Assumes that int is at least 32 bits and that nothing needs more than
  39  * 8-byte alignment.
  40  */
  41
  42 /* COOKIE provides some bad-pointer protection. */
  43 #define COOKIE  "SACOOKIE"
  44
  45 struct sized_array {
  46         int     n;
  47         int     sz;
  48 #if     defined(COOKIE)
  49         char    cookie[8];
  50 #endif
  51 };
  52
  53
  54 void *
  55 sized_array(size_t n, size_t sz)
  56 {
  57         struct sized_array *sa;
  58         size_t total;
  59
  60         total = sizeof (struct sized_array) + n*sz;
  61
  62         sa = malloc(total);
  63
  64         if (sa == NULL)
  65                 return (NULL);
  66
  67         (void) memset(sa, 0, total);
  68
  69         sa->n = n;
  70         sa->sz = sz;
  71
  72 #if     defined(COOKIE)
  73         (void) memcpy(sa->cookie, COOKIE, sizeof (sa->cookie));
  74 #endif
  75
  76         return ((void *)(sa + 1));
  77 }
  78
  79 void
  80 sized_array_free(void *p)
  81 {
  82         struct sized_array *sa;
  83
  84         if (p == NULL)
  85                 return;
  86
  87         sa = ((struct sized_array *)p)-1;
  88
  89 #if     defined(COOKIE)
  90         assert(memcmp(sa->cookie, COOKIE, sizeof (sa->cookie)) == 0);
  91 #endif
  92
  93         free(sa);
  94 }
  95
  96 size_t
  97 sized_array_n(void *p)
  98 {
  99         struct sized_array *sa;
 100
 101         sa = ((struct sized_array *)p)-1;
 102
 103 #if     defined(COOKIE)
 104         assert(memcmp(sa->cookie, COOKIE, sizeof (sa->cookie)) == 0);
 105 #endif
 106
 107         return (sa->n);
 108 }
 109
 110 size_t
 111 sized_array_sz(void *p)
 112 {
 113         struct sized_array *sa;
 114
 115         sa = ((struct sized_array *)p)-1;
 116
 117 #if     defined(COOKIE)
 118         assert(memcmp(sa->cookie, COOKIE, sizeof (sa->cookie)) == 0);
 119 #endif
 120
 121         return (sa->sz);
 122 }