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 (at) 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 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 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 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 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
Indexes created Sat Sep 20 22:09:52 GMT 2025