1 /*
2  * This file is part of strace test suite.
3  *
4  * Copyright (c) 2016 Dmitry V. Levin <ldv@altlinux.org>
5  * All rights reserved.
6  *
7  * Redistribution and use in source and binary forms, with or without
8  * modification, are permitted provided that the following conditions
9  * are met:
10  * 1. Redistributions of source code must retain the above copyright
11  *    notice, this list of conditions and the following disclaimer.
12  * 2. Redistributions in binary form must reproduce the above copyright
13  *    notice, this list of conditions and the following disclaimer in the
14  *    documentation and/or other materials provided with the distribution.
15  * 3. The name of the author may not be used to endorse or promote products
16  *    derived from this software without specific prior written permission.
17  *
18  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28  */
29 
30 #include "tests.h"
31 #include <assert.h>
32 #include <stdio.h>
33 #include <stdlib.h>
34 #include <string.h>
35 #include <unistd.h>
36 #include <sys/param.h>
37 
38 unsigned long
inode_of_sockfd(const int fd)39 inode_of_sockfd(const int fd)
40 {
41 	assert(fd >= 0);
42 
43 	char linkpath[sizeof("/proc/self/fd/%u") + sizeof(int) * 3];
44 	assert(snprintf(linkpath, sizeof(linkpath), "/proc/self/fd/%u", fd)
45 	       < (int) sizeof(linkpath));
46 
47 	char path[PATH_MAX + 1];
48 	const ssize_t path_len = readlink(linkpath, path, sizeof(path) - 1);
49 	if (path_len < 0)
50 		perror_msg_and_fail("readlink: %s", linkpath);
51 	path[path_len] = '\0';
52 
53 	static const char prefix[] = "socket:[";
54 	const size_t prefix_len = sizeof(prefix) - 1;
55 	assert(strncmp(path, prefix, prefix_len) == 0
56 	       && path[path_len - 1] == ']');
57 
58 	return strtoul(path + prefix_len, NULL, 10);
59 }
60