Home | History | Annotate | Download | only in gen
      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 #pragma ident	"%Z%%M%	%I%	%E% SMI"
     28 
     29 #include "lint.h"
     30 #include <libc.h>
     31 #include <fcntl.h>
     32 #include <stdlib.h>
     33 #include <unistd.h>
     34 #include <sys/types.h>
     35 #include <sys/stat.h>
     36 #include <sys/auxv.h>
     37 #include <mtlib.h>
     38 #include <thread.h>
     39 #include <synch.h>
     40 #include <atomic.h>
     41 
     42 static mutex_t auxlock = DEFAULTMUTEX;
     43 
     44 /*
     45  * Get auxiliary entry.
     46  * Returns pointer to entry, or 0 if entry does not exist.
     47  */
     48 static auxv_t *
     49 _getaux(int type)
     50 {
     51 	static auxv_t *auxb = NULL;
     52 	static size_t nauxv = 0;
     53 	ssize_t i;
     54 
     55 	/*
     56 	 * The first time through, read the initial aux vector that was
     57 	 * passed to the process at exec(2).  Only do this once.
     58 	 */
     59 	if (auxb == NULL) {
     60 		lmutex_lock(&auxlock);
     61 		if (auxb == NULL) {
     62 			struct stat statb;
     63 			auxv_t *buf = NULL;
     64 			int fd;
     65 
     66 			if ((fd = open("/proc/self/auxv", O_RDONLY)) != -1 &&
     67 			    fstat(fd, &statb) != -1)
     68 				buf = libc_malloc(
     69 				    statb.st_size + sizeof (auxv_t));
     70 
     71 			if (buf != NULL) {
     72 				i = read(fd, buf, statb.st_size);
     73 				if (i != -1) {
     74 					nauxv = i / sizeof (auxv_t);
     75 					buf[nauxv].a_type = AT_NULL;
     76 				} else {
     77 					libc_free(buf);
     78 					buf = NULL;
     79 				}
     80 			}
     81 
     82 			if (fd != -1)
     83 				(void) close(fd);
     84 
     85 			membar_producer();
     86 			auxb = buf;
     87 		}
     88 		lmutex_unlock(&auxlock);
     89 	}
     90 	membar_consumer();
     91 
     92 	/*
     93 	 * Scan the auxiliary entries looking for the required type.
     94 	 */
     95 	for (i = 0; i < nauxv; i++)
     96 		if (auxb[i].a_type == type)
     97 			return (&auxb[i]);
     98 
     99 	/*
    100 	 * No auxiliary array (static executable) or entry not found.
    101 	 */
    102 	return ((auxv_t *)0);
    103 }
    104 
    105 /*
    106  * These two routines are utilities exported to the rest of libc.
    107  */
    108 
    109 long
    110 ___getauxval(int type)
    111 {
    112 	auxv_t *auxp;
    113 
    114 	if ((auxp = _getaux(type)) != (auxv_t *)0)
    115 		return (auxp->a_un.a_val);
    116 	return (0);
    117 }
    118 
    119 void *
    120 ___getauxptr(int type)
    121 {
    122 	auxv_t *auxp;
    123 
    124 	if ((auxp = _getaux(type)) != (auxv_t *)0)
    125 		return (auxp->a_un.a_ptr);
    126 	return (0);
    127 }
    128