1 /* $NetBSD: fdpass.c,v 1.1 2012/08/13 11:15:05 christos Exp $ */
2 /* $OpenBSD: monitor_fdpass.c,v 1.19 2010/01/12 00:58:25 djm Exp $ */
3 /*
4 * Copyright 2001 Niels Provos <provos@citi.umich.edu>
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 *
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 <sys/cdefs.h>
29 __RCSID("$NetBSD: fdpass.c,v 1.1 2012/08/13 11:15:05 christos Exp $");
30 #include <sys/types.h>
31 #include <sys/socket.h>
32 #include <sys/uio.h>
33 #include <sys/wait.h>
34
35 #include <stdio.h>
36 #include <errno.h>
37 #include <err.h>
38 #include <stdlib.h>
39 #include <unistd.h>
40 #include <fcntl.h>
41 #include <poll.h>
42 #include <string.h>
43
44 static int debug;
45
46 static int
send_fd(int sock,int fd)47 send_fd(int sock, int fd)
48 {
49 struct msghdr msg;
50 union {
51 struct cmsghdr hdr;
52 char buf[1024];
53 } cmsgbuf;
54 struct cmsghdr *cmsg;
55 struct iovec vec;
56 char ch = '\0';
57 ssize_t n;
58 struct pollfd pfd;
59
60 if (sizeof(cmsgbuf.buf) < CMSG_SPACE(sizeof(int)))
61 errx(1, "%s: %zu < %zu, recompile", __func__,
62 sizeof(cmsgbuf.buf), CMSG_SPACE(sizeof(int)));
63
64 memset(&msg, 0, sizeof(msg));
65 msg.msg_control = &cmsgbuf.buf;
66 msg.msg_controllen = CMSG_SPACE(sizeof(int));
67 cmsg = CMSG_FIRSTHDR(&msg);
68 cmsg->cmsg_len = CMSG_LEN(sizeof(int));
69 cmsg->cmsg_level = SOL_SOCKET;
70 cmsg->cmsg_type = SCM_RIGHTS;
71 *(int *)CMSG_DATA(cmsg) = fd;
72 msg.msg_controllen = cmsg->cmsg_len;
73
74 vec.iov_base = &ch;
75 vec.iov_len = 1;
76 msg.msg_iov = &vec;
77 msg.msg_iovlen = 1;
78
79 pfd.fd = sock;
80 pfd.events = POLLOUT;
81 while ((n = sendmsg(sock, &msg, 0)) == -1 &&
82 (errno == EAGAIN || errno == EINTR)) {
83 (void)poll(&pfd, 1, -1);
84 }
85 switch (n) {
86 case -1:
87 err(1, "%s: sendmsg(%d)", __func__, fd);
88 case 1:
89 if (debug)
90 fprintf(stderr, "%d: send fd %d\n", getpid(), fd);
91 return 0;
92 default:
93 errx(1, "%s: sendmsg: expected sent 1 got %ld",
94 __func__, (long)n);
95 }
96 }
97
98 static int
recv_fd(int sock)99 recv_fd(int sock)
100 {
101 struct msghdr msg;
102 union {
103 struct cmsghdr hdr;
104 char buf[1024];
105 } cmsgbuf;
106 struct cmsghdr *cmsg;
107 struct iovec vec;
108 ssize_t n;
109 char ch;
110 int fd;
111 struct pollfd pfd;
112
113 if (sizeof(cmsgbuf.buf) < CMSG_SPACE(sizeof(int)))
114 errx(1, "%s: %zu < %zu, recompile", __func__,
115 sizeof(cmsgbuf.buf), CMSG_SPACE(sizeof(int)));
116
117 memset(&msg, 0, sizeof(msg));
118 vec.iov_base = &ch;
119 vec.iov_len = 1;
120 msg.msg_iov = &vec;
121 msg.msg_iovlen = 1;
122 msg.msg_control = &cmsgbuf.buf;
123 msg.msg_controllen = CMSG_SPACE(sizeof(int));
124
125 pfd.fd = sock;
126 pfd.events = POLLIN;
127 while ((n = recvmsg(sock, &msg, 0)) == -1 &&
128 (errno == EAGAIN || errno == EINTR)) {
129 (void)poll(&pfd, 1, -1);
130 }
131 switch (n) {
132 case -1:
133 err(1, "%s: recvmsg", __func__);
134 case 1:
135 break;
136 default:
137 errx(1, "%s: recvmsg: expected received 1 got %ld",
138 __func__, (long)n);
139 }
140
141 cmsg = CMSG_FIRSTHDR(&msg);
142 if (cmsg == NULL)
143 errx(1, "%s: no message header", __func__);
144
145 if (cmsg->cmsg_type != SCM_RIGHTS)
146 err(1, "%s: expected type %d got %d", __func__,
147 SCM_RIGHTS, cmsg->cmsg_type);
148 fd = (*(int *)CMSG_DATA(cmsg));
149 if (debug)
150 fprintf(stderr, "%d: recv fd %d\n", getpid(), fd);
151 return fd;
152 }
153
154 static void usage(void) __attribute__((__noreturn__));
155
156 static void
usage(void)157 usage(void)
158 {
159 fprintf(stderr, "Usage: %s [-vd] -i <input> -o <output>\n"
160 "\t %s [-v] -p <progname>\n", getprogname(), getprogname());
161 exit(EXIT_FAILURE);
162 }
163
164 int
main(int argc,char * argv[])165 main(int argc, char *argv[])
166 {
167 int s[2], fd, status, c, verbose;
168 char buf[1024], *prog;
169
170 prog = NULL;
171 s[0] = s[1] = -1;
172 verbose = 0;
173
174 while ((c = getopt(argc, argv, "di:o:p:")) != -1)
175 switch (c) {
176 case 'd':
177 debug++;
178 break;
179 case 'i':
180 s[0] = atoi(optarg);
181 break;
182 case 'o':
183 s[1] = atoi(optarg);
184 break;
185 case 'p':
186 prog = optarg;
187 break;
188 default:
189 usage();
190 }
191
192 if ((s[0] == -1 && s[1] != -1) || (s[0] != -1 && s[1] == -1))
193 usage();
194
195 if (s[0] == -1) {
196 if (socketpair(AF_LOCAL, SOCK_DGRAM, 0, s) == -1)
197 err(1, "socketpair");
198 } else
199 goto recv;
200
201 switch (fork()) {
202 case -1:
203 err(1, "fork");
204 default:
205 fd = open("foo", O_RDWR|O_CREAT|O_TRUNC, 0666);
206 if (fd == -1)
207 err(1, "open");
208 send_fd(s[0], fd);
209 wait(&status);
210 return 0;
211 case 0:
212 if (prog != NULL) {
213 char i[64], o[64];
214 snprintf(i, sizeof(i), "%d", s[0]);
215 snprintf(o, sizeof(o), "%d", s[1]);
216 execlp(prog, prog, "-i", i, "-o", o, NULL);
217 err(1, "execlp");
218 }
219 recv:
220 fd = recv_fd(s[1]);
221 if (verbose) {
222 snprintf(buf, sizeof(buf), "ls -l /proc/%d/fd",
223 getpid());
224 system(buf);
225 }
226 if (write(fd, "foo\n", 4) == -1)
227 err(1, "write");
228 close(fd);
229 return 0;
230 }
231 }
232