xref: /illumos-gate/usr/src/lib/libidmap/common/sized_array.c (revision 0a1278f26ea4b7c8c0285d4f2d6c5b680904aa01)
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 }
123