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/*
28 * Copyright 2019 OmniOS Community Edition (OmniOSce) Association.
29 */
30
31#pragma weak _isaexec = isaexec
32
33#include "lint.h"
34#include <sys/types.h>
35#include <sys/systeminfo.h>
36#include <unistd.h>
37#include <string.h>
38#include <errno.h>
39#include <limits.h>
40#include <stdarg.h>
41#include <stdlib.h>
42
43/*
44 * This is a utility routine to allow wrapper programs to simply
45 * implement the isalist exec algorithms.  See PSARC/1997/220.
46 */
47int
48isaexec(const char *execname, char *const *argv, char *const *envp)
49{
50	const char *fname;
51	char *isalist;
52	char *pathname;
53	char *str;
54	char *lasts;
55	size_t isalen = 255;		/* wild guess */
56	size_t len;
57	int saved_errno;
58
59	/*
60	 * Extract the isalist(5) for userland from the kernel.
61	 */
62	isalist = malloc(isalen);
63	do {
64		long ret = sysinfo(SI_ISALIST, isalist, isalen);
65		if (ret == -1l) {
66			free(isalist);
67			errno = ENOENT;
68			return (-1);
69		}
70		if (ret > isalen) {
71			isalen = ret;
72			isalist = reallocf(isalist, isalen);
73		} else {
74			break;
75		}
76	} while (isalist != NULL);
77
78	if (isalist == NULL) {
79		/*
80		 * Then either a malloc or a realloc failed.
81		 */
82		errno = EAGAIN;
83		return (-1);
84	}
85
86	/*
87	 * Allocate a full pathname buffer.  The sum of the lengths of the
88	 * 'path' and isalist strings is guaranteed to be big enough.
89	 */
90	len = strlen(execname) + isalen;
91	if ((pathname = malloc(len)) == NULL) {
92		free(isalist);
93		errno = EAGAIN;
94		return (-1);
95	}
96
97	/*
98	 * Break the exec name into directory and file name components.
99	 */
100	(void) strcpy(pathname, execname);
101	if ((str = strrchr(pathname, '/')) != NULL) {
102		*++str = '\0';
103		fname = execname + (str - pathname);
104	} else {
105		fname = execname;
106		*pathname = '\0';
107	}
108	len = strlen(pathname);
109
110	/*
111	 * For each name in the isa list, look for an executable file
112	 * with the given file name in the corresponding subdirectory.
113	 * If it's there, exec it.  If it's not there, or the exec
114	 * fails, then run the next version ..
115	 */
116	str = strtok_r(isalist, " ", &lasts);
117	saved_errno = ENOENT;
118	do {
119		(void) strcpy(pathname + len, str);
120		(void) strcat(pathname + len, "/");
121		(void) strcat(pathname + len, fname);
122		if (access(pathname, X_OK) == 0) {
123			/*
124			 * File exists and is marked executable.  Attempt
125			 * to execute the file from the subdirectory,
126			 * using the user-supplied argv and envp.
127			 */
128			(void) execve(pathname, argv, envp);
129
130			/*
131			 * If we failed to exec because of a temporary
132			 * resource shortage, it's better to let our
133			 * caller handle it (free memory, sleep for a while,
134			 * or whatever before retrying) rather than drive
135			 * on to run the "less capable" version.
136			 */
137			if (errno == EAGAIN) {
138				saved_errno = errno;
139				break;
140			}
141		}
142	} while ((str = strtok_r(NULL, " ", &lasts)) != NULL);
143
144	free(pathname);
145	free(isalist);
146
147	errno = saved_errno;
148	return (-1);
149}
150