1 /* $NetBSD: rumpuser_daemonize.c,v 1.2 2011/01/22 14:18:55 pooka Exp $ */ 2 3 /* 4 * Copyright (c) 2010 Antti Kantee. All Rights Reserved. 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS 16 * OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 17 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 18 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 21 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 #include <sys/cdefs.h> 29 #if !defined(lint) 30 __RCSID("$NetBSD: rumpuser_daemonize.c,v 1.2 2011/01/22 14:18:55 pooka Exp $"); 31 #endif /* !lint */ 32 33 #include <sys/types.h> 34 #include <sys/socket.h> 35 36 #include <errno.h> 37 #include <fcntl.h> 38 #include <paths.h> 39 #include <stdio.h> 40 #include <unistd.h> 41 42 static int isdaemonizing; 43 static int daemonpipe[2]; 44 45 #include <rump/rumpuser.h> 46 47 int 48 rumpuser_daemonize_begin(void) 49 { 50 ssize_t n; 51 int error; 52 53 if (isdaemonizing) 54 return EINPROGRESS; 55 isdaemonizing = 1; 56 57 /* 58 * For daemons we need to fork. However, since we can't fork 59 * after rump_init (which creates threads), do it now. Add 60 * a little pipe trickery to make sure we don't exit until the 61 * service is fully inited (i.e. interlocked daemonization). 62 * Actually, use sucketpair since that allows to easily steer 63 * clear of the dreaded sigpipe. 64 * 65 * Note: We do *NOT* host chdir("/"). It's up to the caller to 66 * take care of that or not. 67 */ 68 if (socketpair(PF_LOCAL, SOCK_STREAM, 0, daemonpipe) == -1) { 69 return errno; 70 } 71 72 switch (fork()) { 73 case 0: 74 if (setsid() == -1) { 75 rumpuser_daemonize_done(errno); 76 } 77 return 0; 78 case -1: 79 return errno; 80 default: 81 close(daemonpipe[1]); 82 n = recv(daemonpipe[0], &error, sizeof(error), MSG_NOSIGNAL); 83 if (n == -1) 84 error = errno; 85 else if (n != sizeof(error)) 86 error = ESRCH; 87 _exit(error); 88 /*NOTREACHED*/ 89 } 90 } 91 92 int 93 rumpuser_daemonize_done(int error) 94 { 95 ssize_t n; 96 int fd; 97 98 if (!isdaemonizing) 99 return ENOENT; 100 101 if (error == 0) { 102 fd = open(_PATH_DEVNULL, O_RDWR); 103 if (fd == -1) { 104 error = errno; 105 goto out; 106 } 107 dup2(fd, STDIN_FILENO); 108 dup2(fd, STDOUT_FILENO); 109 dup2(fd, STDERR_FILENO); 110 if (fd > STDERR_FILENO) 111 close(fd); 112 } 113 114 out: 115 n = send(daemonpipe[1], &error, sizeof(error), MSG_NOSIGNAL); 116 if (n != sizeof(error)) 117 return EPIPE; 118 else if (n == -1) 119 return errno; 120 close(daemonpipe[0]); 121 close(daemonpipe[1]); 122 123 return 0; 124 } 125