1 /* $NetBSD: rumpuser_daemonize.c,v 1.3 2012/07/27 09:09:05 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 "rumpuser_port.h" 29 30 #if !defined(lint) 31 __RCSID("$NetBSD: rumpuser_daemonize.c,v 1.3 2012/07/27 09:09:05 pooka Exp $"); 32 #endif /* !lint */ 33 34 #include <sys/types.h> 35 #include <sys/socket.h> 36 37 #include <errno.h> 38 #include <fcntl.h> 39 #include <paths.h> 40 #include <stdio.h> 41 #include <unistd.h> 42 43 static int isdaemonizing; 44 static int daemonpipe[2]; 45 46 #include <rump/rumpuser.h> 47 48 int 49 rumpuser_daemonize_begin(void) 50 { 51 ssize_t n; 52 int error; 53 54 if (isdaemonizing) 55 return EINPROGRESS; 56 isdaemonizing = 1; 57 58 /* 59 * For daemons we need to fork. However, since we can't fork 60 * after rump_init (which creates threads), do it now. Add 61 * a little pipe trickery to make sure we don't exit until the 62 * service is fully inited (i.e. interlocked daemonization). 63 * Actually, use sucketpair since that allows to easily steer 64 * clear of the dreaded sigpipe. 65 * 66 * Note: We do *NOT* host chdir("/"). It's up to the caller to 67 * take care of that or not. 68 */ 69 if (socketpair(PF_LOCAL, SOCK_STREAM, 0, daemonpipe) == -1) { 70 return errno; 71 } 72 73 switch (fork()) { 74 case 0: 75 if (setsid() == -1) { 76 rumpuser_daemonize_done(errno); 77 } 78 return 0; 79 case -1: 80 return errno; 81 default: 82 close(daemonpipe[1]); 83 n = recv(daemonpipe[0], &error, sizeof(error), MSG_NOSIGNAL); 84 if (n == -1) 85 error = errno; 86 else if (n != sizeof(error)) 87 error = ESRCH; 88 _exit(error); 89 /*NOTREACHED*/ 90 } 91 } 92 93 int 94 rumpuser_daemonize_done(int error) 95 { 96 ssize_t n; 97 int fd; 98 99 if (!isdaemonizing) 100 return ENOENT; 101 102 if (error == 0) { 103 fd = open(_PATH_DEVNULL, O_RDWR); 104 if (fd == -1) { 105 error = errno; 106 goto out; 107 } 108 dup2(fd, STDIN_FILENO); 109 dup2(fd, STDOUT_FILENO); 110 dup2(fd, STDERR_FILENO); 111 if (fd > STDERR_FILENO) 112 close(fd); 113 } 114 115 out: 116 n = send(daemonpipe[1], &error, sizeof(error), MSG_NOSIGNAL); 117 if (n != sizeof(error)) 118 return EPIPE; 119 else if (n == -1) 120 return errno; 121 close(daemonpipe[0]); 122 close(daemonpipe[1]); 123 124 return 0; 125 } 126