1 /******************************************************************************* 2 * Copyright (C) 2004-2008 Intel Corp. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions are met: 6 * 7 * - Redistributions of source code must retain the above copyright notice, 8 * this list of conditions and the following disclaimer. 9 * 10 * - Redistributions in binary form must reproduce the above copyright notice, 11 * this list of conditions and the following disclaimer in the documentation 12 * and/or other materials provided with the distribution. 13 * 14 * - Neither the name of Intel Corp. nor the names of its 15 * contributors may be used to endorse or promote products derived from this 16 * software without specific prior written permission. 17 * 18 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS ``AS IS'' 19 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 21 * ARE DISCLAIMED. IN NO EVENT SHALL Intel Corp. OR THE CONTRIBUTORS 22 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 23 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 24 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 25 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 26 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 27 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 28 * POSSIBILITY OF SUCH DAMAGE. 29 *******************************************************************************/ 30 31 #ifdef HAVE_CONFIG_H 32 #include "config.h" 33 #endif 34 35 #ifdef DAEMON 36 37 #include <cstdio> 38 #include <cstdlib> 39 #include <cstring> 40 #include <cerrno> 41 #include <csignal> 42 #include <unistd.h> 43 #include <sys/types.h> 44 #include <sys/stat.h> 45 #include <fcntl.h> 46 #include <syslog.h> 47 #include <pwd.h> 48 49 #include "daemonize.h" 50 51 static RETSIGTYPE child_handler(int signum) 52 { 53 switch (signum) { 54 case SIGALRM: 55 exit(EXIT_FAILURE); 56 break; 57 case SIGUSR1: 58 exit(EXIT_SUCCESS); 59 break; 60 case SIGCHLD: 61 exit(EXIT_FAILURE); 62 break; 63 } 64 } 65 66 void daemonize() 67 { 68 pid_t pid, sid, parent; 69 70 /* Drop user if there is one, and we were run as root */ 71 if (getuid() == 0 || geteuid() == 0) { 72 struct passwd *pw = getpwnam(RUN_AS_USER); 73 if (pw) { 74 //syslog(LOG_NOTICE, "setting user to " RUN_AS_USER); 75 setuid(pw->pw_uid); 76 } 77 } 78 79 /* Trap signals that we expect to recieve */ 80 signal(SIGCHLD, child_handler); 81 signal(SIGUSR1, child_handler); 82 signal(SIGALRM, child_handler); 83 84 /* Fork off the parent process */ 85 pid = fork(); 86 if (pid < 0) { 87 syslog(LOG_ERR, "unable to fork daemon, code=%d (%s)", 88 errno, strerror(errno)); 89 exit(EXIT_FAILURE); 90 } 91 /* If we got a good PID, then we can exit the parent process. */ 92 if (pid > 0) { 93 94 /* Wait for confirmation from the child via SIGTERM or SIGCHLD, or 95 for two seconds to elapse (SIGALRM). pause() should not return. */ 96 alarm(2); 97 pause(); 98 99 exit(EXIT_FAILURE); 100 } 101 102 /* At this point we are executing as the child process */ 103 parent = getppid(); 104 105 signal(SIGCHLD, SIG_DFL); 106 signal(SIGUSR1, SIG_DFL); 107 signal(SIGALRM, SIG_DFL); 108 setTerminationHandler(); 109 110 /* Create a new SID for the child process */ 111 sid = setsid(); 112 if (sid < 0) { 113 syslog(LOG_ERR, 114 "unable to create a new session, code %d (%s)", 115 errno, strerror(errno)); 116 exit(EXIT_FAILURE); 117 } 118 119 /* Change the current working directory. This prevents the current 120 directory from being locked; hence not being able to remove it. */ 121 if ((chdir("/")) < 0) { 122 syslog(LOG_ERR, 123 "unable to change directory to %s, code %d (%s)", 124 "/", errno, strerror(errno)); 125 exit(EXIT_FAILURE); 126 } 127 128 /* Redirect standard files to /dev/null */ 129 freopen("/dev/null", "r", stdin); 130 freopen("/dev/null", "w", stdout); 131 freopen("/dev/null", "w", stderr); 132 133 /* Tell the parent process that we are A-okay */ 134 kill(parent, SIGUSR1); 135 } 136 137 #endif //DAEMON 138 139