xref: /onnv-gate/usr/src/lib/libc/port/gen/getauxv.c (revision 0:68f95e015346)
1*0Sstevel@tonic-gate /*
2*0Sstevel@tonic-gate  * CDDL HEADER START
3*0Sstevel@tonic-gate  *
4*0Sstevel@tonic-gate  * The contents of this file are subject to the terms of the
5*0Sstevel@tonic-gate  * Common Development and Distribution License, Version 1.0 only
6*0Sstevel@tonic-gate  * (the "License").  You may not use this file except in compliance
7*0Sstevel@tonic-gate  * with the License.
8*0Sstevel@tonic-gate  *
9*0Sstevel@tonic-gate  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10*0Sstevel@tonic-gate  * or http://www.opensolaris.org/os/licensing.
11*0Sstevel@tonic-gate  * See the License for the specific language governing permissions
12*0Sstevel@tonic-gate  * and limitations under the License.
13*0Sstevel@tonic-gate  *
14*0Sstevel@tonic-gate  * When distributing Covered Code, include this CDDL HEADER in each
15*0Sstevel@tonic-gate  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16*0Sstevel@tonic-gate  * If applicable, add the following below this CDDL HEADER, with the
17*0Sstevel@tonic-gate  * fields enclosed by brackets "[]" replaced with your own identifying
18*0Sstevel@tonic-gate  * information: Portions Copyright [yyyy] [name of copyright owner]
19*0Sstevel@tonic-gate  *
20*0Sstevel@tonic-gate  * CDDL HEADER END
21*0Sstevel@tonic-gate  */
22*0Sstevel@tonic-gate /*
23*0Sstevel@tonic-gate  * Copyright 2004 Sun Microsystems, Inc.  All rights reserved.
24*0Sstevel@tonic-gate  * Use is subject to license terms.
25*0Sstevel@tonic-gate  */
26*0Sstevel@tonic-gate 
27*0Sstevel@tonic-gate #pragma ident	"%Z%%M%	%I%	%E% SMI"
28*0Sstevel@tonic-gate 
29*0Sstevel@tonic-gate #include "lint.h"
30*0Sstevel@tonic-gate #include <libc.h>
31*0Sstevel@tonic-gate #include <fcntl.h>
32*0Sstevel@tonic-gate #include <stdlib.h>
33*0Sstevel@tonic-gate #include <unistd.h>
34*0Sstevel@tonic-gate #include <sys/types.h>
35*0Sstevel@tonic-gate #include <sys/stat.h>
36*0Sstevel@tonic-gate #include <sys/auxv.h>
37*0Sstevel@tonic-gate #include <mtlib.h>
38*0Sstevel@tonic-gate #include <thread.h>
39*0Sstevel@tonic-gate #include <synch.h>
40*0Sstevel@tonic-gate 
41*0Sstevel@tonic-gate static mutex_t auxlock = DEFAULTMUTEX;
42*0Sstevel@tonic-gate 
43*0Sstevel@tonic-gate /*
44*0Sstevel@tonic-gate  * Get auxiliary entry.
45*0Sstevel@tonic-gate  * Returns pointer to entry, or 0 if entry does not exist.
46*0Sstevel@tonic-gate  */
47*0Sstevel@tonic-gate static auxv_t *
48*0Sstevel@tonic-gate _getaux(int type)
49*0Sstevel@tonic-gate {
50*0Sstevel@tonic-gate 	static auxv_t *auxb = NULL;
51*0Sstevel@tonic-gate 	static size_t nauxv = 0;
52*0Sstevel@tonic-gate 	ssize_t i;
53*0Sstevel@tonic-gate 
54*0Sstevel@tonic-gate 	/*
55*0Sstevel@tonic-gate 	 * The first time through, read the initial aux vector that was
56*0Sstevel@tonic-gate 	 * passed to the process at exec(2).  Only do this once.
57*0Sstevel@tonic-gate 	 */
58*0Sstevel@tonic-gate 	if (auxb == NULL) {
59*0Sstevel@tonic-gate 		struct stat statb;
60*0Sstevel@tonic-gate 		int fd;
61*0Sstevel@tonic-gate 
62*0Sstevel@tonic-gate 		lmutex_lock(&auxlock);
63*0Sstevel@tonic-gate 
64*0Sstevel@tonic-gate 		if (auxb == NULL) {
65*0Sstevel@tonic-gate 			if ((fd = open("/proc/self/auxv", O_RDONLY)) != -1 &&
66*0Sstevel@tonic-gate 			    fstat(fd, &statb) != -1)
67*0Sstevel@tonic-gate 				auxb = libc_malloc(
68*0Sstevel@tonic-gate 				    statb.st_size + sizeof (auxv_t));
69*0Sstevel@tonic-gate 
70*0Sstevel@tonic-gate 			if (auxb != NULL) {
71*0Sstevel@tonic-gate 				i = read(fd, auxb, statb.st_size);
72*0Sstevel@tonic-gate 				if (i != -1) {
73*0Sstevel@tonic-gate 					nauxv = i / sizeof (auxv_t);
74*0Sstevel@tonic-gate 					auxb[nauxv].a_type = AT_NULL;
75*0Sstevel@tonic-gate 				} else {
76*0Sstevel@tonic-gate 					libc_free(auxb);
77*0Sstevel@tonic-gate 					auxb = NULL;
78*0Sstevel@tonic-gate 				}
79*0Sstevel@tonic-gate 			}
80*0Sstevel@tonic-gate 
81*0Sstevel@tonic-gate 			if (fd != -1)
82*0Sstevel@tonic-gate 				(void) close(fd);
83*0Sstevel@tonic-gate 		}
84*0Sstevel@tonic-gate 
85*0Sstevel@tonic-gate 		lmutex_unlock(&auxlock);
86*0Sstevel@tonic-gate 	}
87*0Sstevel@tonic-gate 
88*0Sstevel@tonic-gate 	/*
89*0Sstevel@tonic-gate 	 * Scan the auxiliary entries looking for the required type.
90*0Sstevel@tonic-gate 	 */
91*0Sstevel@tonic-gate 	for (i = 0; i < nauxv; i++)
92*0Sstevel@tonic-gate 		if (auxb[i].a_type == type)
93*0Sstevel@tonic-gate 			return (&auxb[i]);
94*0Sstevel@tonic-gate 
95*0Sstevel@tonic-gate 	/*
96*0Sstevel@tonic-gate 	 * No auxiliary array (static executable) or entry not found.
97*0Sstevel@tonic-gate 	 */
98*0Sstevel@tonic-gate 	return ((auxv_t *)0);
99*0Sstevel@tonic-gate }
100*0Sstevel@tonic-gate 
101*0Sstevel@tonic-gate /*
102*0Sstevel@tonic-gate  * These two routines are utilities exported to the rest of libc.
103*0Sstevel@tonic-gate  */
104*0Sstevel@tonic-gate 
105*0Sstevel@tonic-gate long
106*0Sstevel@tonic-gate ___getauxval(int type)
107*0Sstevel@tonic-gate {
108*0Sstevel@tonic-gate 	auxv_t *auxp;
109*0Sstevel@tonic-gate 
110*0Sstevel@tonic-gate 	if ((auxp = _getaux(type)) != (auxv_t *)0)
111*0Sstevel@tonic-gate 		return (auxp->a_un.a_val);
112*0Sstevel@tonic-gate 	return (0);
113*0Sstevel@tonic-gate }
114*0Sstevel@tonic-gate 
115*0Sstevel@tonic-gate void *
116*0Sstevel@tonic-gate ___getauxptr(int type)
117*0Sstevel@tonic-gate {
118*0Sstevel@tonic-gate 	auxv_t *auxp;
119*0Sstevel@tonic-gate 
120*0Sstevel@tonic-gate 	if ((auxp = _getaux(type)) != (auxv_t *)0)
121*0Sstevel@tonic-gate 		return (auxp->a_un.a_ptr);
122*0Sstevel@tonic-gate 	return (0);
123*0Sstevel@tonic-gate }
124