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 2008 Sun Microsystems, Inc. All rights reserved.
24 * Use is subject to license terms.
25 */
26
27 #include "lint.h"
28 #include <libc.h>
29 #include <fcntl.h>
30 #include <stdlib.h>
31 #include <unistd.h>
32 #include <sys/types.h>
33 #include <sys/stat.h>
34 #include <sys/auxv.h>
35 #include <mtlib.h>
36 #include <thread.h>
37 #include <synch.h>
38 #include <atomic.h>
39
40 static mutex_t auxlock = DEFAULTMUTEX;
41
42 /*
43 * Get auxiliary entry.
44 * Returns pointer to entry, or 0 if entry does not exist.
45 */
46 static auxv_t *
_getaux(int type)47 _getaux(int type)
48 {
49 static auxv_t *auxb = NULL;
50 static size_t nauxv = 0;
51 ssize_t i;
52
53 /*
54 * The first time through, read the initial aux vector that was
55 * passed to the process at exec(2). Only do this once.
56 */
57 if (auxb == NULL) {
58 lmutex_lock(&auxlock);
59 if (auxb == NULL) {
60 struct stat statb;
61 auxv_t *buf = NULL;
62 int fd;
63
64 if ((fd = open("/proc/self/auxv", O_RDONLY)) != -1 &&
65 fstat(fd, &statb) != -1)
66 buf = libc_malloc(
67 statb.st_size + sizeof (auxv_t));
68
69 if (buf != NULL) {
70 i = read(fd, buf, statb.st_size);
71 if (i != -1) {
72 nauxv = i / sizeof (auxv_t);
73 buf[nauxv].a_type = AT_NULL;
74 } else {
75 libc_free(buf);
76 buf = NULL;
77 }
78 }
79
80 if (fd != -1)
81 (void) close(fd);
82
83 membar_producer();
84 auxb = buf;
85 }
86 lmutex_unlock(&auxlock);
87 }
88 membar_consumer();
89
90 /*
91 * Scan the auxiliary entries looking for the required type.
92 */
93 for (i = 0; i < nauxv; i++)
94 if (auxb[i].a_type == type)
95 return (&auxb[i]);
96
97 /*
98 * No auxiliary array (static executable) or entry not found.
99 */
100 return ((auxv_t *)0);
101 }
102
103 /*
104 * These two routines are utilities exported to the rest of libc.
105 */
106
107 long
___getauxval(int type)108 ___getauxval(int type)
109 {
110 auxv_t *auxp;
111
112 if ((auxp = _getaux(type)) != (auxv_t *)0)
113 return (auxp->a_un.a_val);
114 return (0);
115 }
116
117 void *
___getauxptr(int type)118 ___getauxptr(int type)
119 {
120 auxv_t *auxp;
121
122 if ((auxp = _getaux(type)) != (auxv_t *)0)
123 return (auxp->a_un.a_ptr);
124 return (0);
125 }
126