1 /* $NetBSD: rumpuser_daemonize.c,v 1.4 2012/11/18 19:29:40 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 1.4 2012/11/18 19:29:40 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 <stdio.h> 40 #include <unistd.h> 41 42 #ifdef __sun__ 43 #define _PATH_DEVNULL "/dev/null" 44 #else 45 #include <paths.h> 46 #endif 47 48 static int isdaemonizing; 49 static int daemonpipe[2]; 50 51 #include <rump/rumpuser.h> 52 53 int 54 rumpuser_daemonize_begin(void) 55 { 56 ssize_t n; 57 int error; 58 59 if (isdaemonizing) 60 return EINPROGRESS; 61 isdaemonizing = 1; 62 63 /* 64 * For daemons we need to fork. However, since we can't fork 65 * after rump_init (which creates threads), do it now. Add 66 * a little pipe trickery to make sure we don't exit until the 67 * service is fully inited (i.e. interlocked daemonization). 68 * Actually, use sucketpair since that allows to easily steer 69 * clear of the dreaded sigpipe. 70 * 71 * Note: We do *NOT* host chdir("/"). It's up to the caller to 72 * take care of that or not. 73 */ 74 if (socketpair(PF_LOCAL, SOCK_STREAM, 0, daemonpipe) == -1) { 75 return errno; 76 } 77 78 switch (fork()) { 79 case 0: 80 if (setsid() == -1) { 81 rumpuser_daemonize_done(errno); 82 } 83 return 0; 84 case -1: 85 return errno; 86 default: 87 close(daemonpipe[1]); 88 n = recv(daemonpipe[0], &error, sizeof(error), MSG_NOSIGNAL); 89 if (n == -1) 90 error = errno; 91 else if (n != sizeof(error)) 92 error = ESRCH; 93 _exit(error); 94 /*NOTREACHED*/ 95 } 96 } 97 98 int 99 rumpuser_daemonize_done(int error) 100 { 101 ssize_t n; 102 int fd; 103 104 if (!isdaemonizing) 105 return ENOENT; 106 107 if (error == 0) { 108 fd = open(_PATH_DEVNULL, O_RDWR); 109 if (fd == -1) { 110 error = errno; 111 goto out; 112 } 113 dup2(fd, STDIN_FILENO); 114 dup2(fd, STDOUT_FILENO); 115 dup2(fd, STDERR_FILENO); 116 if (fd > STDERR_FILENO) 117 close(fd); 118 } 119 120 out: 121 n = send(daemonpipe[1], &error, sizeof(error), MSG_NOSIGNAL); 122 if (n != sizeof(error)) 123 return EPIPE; 124 else if (n == -1) 125 return errno; 126 close(daemonpipe[0]); 127 close(daemonpipe[1]); 128 129 return 0; 130 } 131