1 /*
2  * Copyright (c) 2014-2015 Dmitry V. Levin <ldv@altlinux.org>
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. The name of the author may not be used to endorse or promote products
14  *    derived from this software without specific prior written permission.
15  *
16  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
17  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
18  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
19  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
20  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
21  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
22  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
23  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
24  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
25  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
26  */
27 
28 #include <assert.h>
29 #include <string.h>
30 #include <stdlib.h>
31 #include <unistd.h>
32 #include <errno.h>
33 #include <fcntl.h>
34 #include <sys/socket.h>
35 #include <sys/wait.h>
36 
main(int ac,const char ** av)37 int main(int ac, const char **av)
38 {
39 	int i;
40 	int data = 0;
41 	struct iovec iov = {
42 		.iov_base = &data,
43 		.iov_len = sizeof(iov)
44 	};
45 
46 	while ((i = open("/dev/null", O_RDWR)) < 3)
47 		assert(i >= 0);
48 	(void) close(3);
49 
50 	int sv[2];
51 	assert(socketpair(AF_UNIX, SOCK_STREAM, 0, sv) == 0);
52 	int one = 1;
53 	assert(setsockopt(sv[0], SOL_SOCKET, SO_PASSCRED, &one, sizeof(one)) == 0);
54 
55 	pid_t pid = fork();
56 	assert(pid >= 0);
57 
58 	if (pid) {
59 		assert(close(sv[0]) == 0);
60 		assert(dup2(sv[1], 1) == 1);
61 		assert(close(sv[1]) == 0);
62 
63 		int fds[ac];
64 		assert((fds[0] = open("/dev/null", O_RDWR)) == 3);
65 		for (i = 1; i < ac; ++i)
66 			assert((fds[i] = open(av[i], O_RDONLY)) == i + 3);
67 
68 		union {
69 			struct cmsghdr cmsg;
70 			char buf[CMSG_LEN(sizeof(fds))];
71 		} control;
72 
73 		control.cmsg.cmsg_level = SOL_SOCKET;
74 		control.cmsg.cmsg_type = SCM_RIGHTS;
75 		control.cmsg.cmsg_len = CMSG_LEN(sizeof(fds));
76 		memcpy(CMSG_DATA(&control.cmsg), fds, sizeof(fds));
77 
78 		struct msghdr mh = {
79 			.msg_iov = &iov,
80 			.msg_iovlen = 1,
81 			.msg_control = &control,
82 			.msg_controllen = sizeof(control)
83 		};
84 
85 		assert(sendmsg(1, &mh, 0) == sizeof(iov));
86 		assert(close(1) == 0);
87 
88                 int status;
89 		assert(waitpid(pid, &status, 0) == pid);
90 		assert(status == 0);
91 	} else {
92 		assert(close(sv[1]) == 0);
93 		assert(dup2(sv[0], 0) == 0);
94 		assert(close(sv[0]) == 0);
95 
96 		struct cmsghdr control[4 + ac * sizeof(int) / sizeof(struct cmsghdr)];
97 
98 		struct msghdr mh = {
99 			.msg_iov = &iov,
100 			.msg_iovlen = 1,
101 			.msg_control = control,
102 			.msg_controllen = sizeof(control)
103 		};
104 
105 		assert(recvmsg(0, &mh, 0) == sizeof(iov));
106 		assert(close(0) == 0);
107 	}
108 
109 	return 0;
110 }
111