| /* |
| * This code is mainly taken from Doug Potter's page |
| * |
| * http://www-theorie.physik.unizh.ch/~dpotter/howto/daemonize |
| * |
| * I contacted him 2007-04-16 about the license for the original code, |
| * he replied it is Public Domain. Use the URL above to get the original |
| * Public Domain version if you want it. |
| * |
| * This version is LGPL2 and is (c)2006 - 2013 Andy Green <andy@warmcat.com> |
| */ |
| |
| #include <stdlib.h> |
| #include <string.h> |
| #include <stdio.h> |
| #include <signal.h> |
| #include <sys/types.h> |
| #include <sys/stat.h> |
| #include <fcntl.h> |
| #include <limits.h> |
| #include <unistd.h> |
| #include <errno.h> |
| |
| #include "private-libwebsockets.h" |
| |
| int pid_daemon; |
| static char *lock_path; |
| |
| int get_daemonize_pid() |
| { |
| return pid_daemon; |
| } |
| |
| static void |
| child_handler(int signum) |
| { |
| int fd; |
| int len; |
| int sent; |
| char sz[20]; |
| |
| switch (signum) { |
| |
| case SIGALRM: /* timedout daemonizing */ |
| exit(1); |
| break; |
| |
| case SIGUSR1: /* positive confirmation we daemonized well */ |
| /* Create the lock file as the current user */ |
| |
| fd = open(lock_path, O_TRUNC | O_RDWR | O_CREAT, 0640); |
| if (fd < 0) { |
| fprintf(stderr, |
| "unable to create lock file %s, code=%d (%s)\n", |
| lock_path, errno, strerror(errno)); |
| exit(1); |
| } |
| len = sprintf(sz, "%u", pid_daemon); |
| sent = write(fd, sz, len); |
| if (sent != len) |
| fprintf(stderr, |
| "unable write pid to lock file %s, code=%d (%s)\n", |
| lock_path, errno, strerror(errno)); |
| |
| close(fd); |
| exit(!!(sent == len)); |
| |
| case SIGCHLD: /* daemonization failed */ |
| exit(1); |
| break; |
| } |
| } |
| |
| static void lws_daemon_closing(int sigact) |
| { |
| if (getpid() == pid_daemon) |
| if (lock_path) { |
| unlink(lock_path); |
| free(lock_path); |
| lock_path = NULL; |
| } |
| |
| kill(getpid(), SIGKILL); |
| } |
| |
| /* |
| * You just need to call this from your main(), when it |
| * returns you are all set "in the background" decoupled |
| * from the console you were started from. |
| * |
| * The process context you called from has been terminated then. |
| */ |
| |
| LWS_VISIBLE int |
| lws_daemonize(const char *_lock_path) |
| { |
| pid_t sid, parent; |
| int fd; |
| char buf[10]; |
| int n, ret; |
| struct sigaction act; |
| |
| /* already a daemon */ |
| if (getppid() == 1) |
| return 1; |
| |
| fd = open(_lock_path, O_RDONLY); |
| if (fd >= 0) { |
| n = read(fd, buf, sizeof(buf)); |
| close(fd); |
| if (n) { |
| n = atoi(buf); |
| ret = kill(n, 0); |
| if (ret >= 0) { |
| fprintf(stderr, |
| "Daemon already running from pid %d\n", n); |
| exit(1); |
| } |
| fprintf(stderr, |
| "Removing stale lock file %s from dead pid %d\n", |
| _lock_path, n); |
| unlink(lock_path); |
| } |
| } |
| |
| n = strlen(_lock_path) + 1; |
| lock_path = malloc(n); |
| if (!lock_path) { |
| fprintf(stderr, "Out of mem in lws_daemonize\n"); |
| return 1; |
| } |
| strcpy(lock_path, _lock_path); |
| |
| /* Trap signals that we expect to recieve */ |
| signal(SIGCHLD, child_handler); /* died */ |
| signal(SIGUSR1, child_handler); /* was happy */ |
| signal(SIGALRM, child_handler); /* timeout daemonizing */ |
| |
| /* Fork off the parent process */ |
| pid_daemon = fork(); |
| if (pid_daemon < 0) { |
| fprintf(stderr, "unable to fork daemon, code=%d (%s)", |
| errno, strerror(errno)); |
| exit(1); |
| } |
| |
| /* If we got a good PID, then we can exit the parent process. */ |
| if (pid_daemon > 0) { |
| |
| /* |
| * Wait for confirmation signal from the child via |
| * SIGCHILD / USR1, or for two seconds to elapse |
| * (SIGALRM). pause() should not return. |
| */ |
| alarm(2); |
| |
| pause(); |
| /* should not be reachable */ |
| exit(1); |
| } |
| |
| /* At this point we are executing as the child process */ |
| parent = getppid(); |
| pid_daemon = getpid(); |
| |
| /* Cancel certain signals */ |
| signal(SIGCHLD, SIG_DFL); /* A child process dies */ |
| signal(SIGTSTP, SIG_IGN); /* Various TTY signals */ |
| signal(SIGTTOU, SIG_IGN); |
| signal(SIGTTIN, SIG_IGN); |
| signal(SIGHUP, SIG_IGN); /* Ignore hangup signal */ |
| |
| /* Change the file mode mask */ |
| umask(0); |
| |
| /* Create a new SID for the child process */ |
| sid = setsid(); |
| if (sid < 0) { |
| fprintf(stderr, |
| "unable to create a new session, code %d (%s)", |
| errno, strerror(errno)); |
| exit(1); |
| } |
| |
| /* |
| * Change the current working directory. This prevents the current |
| * directory from being locked; hence not being able to remove it. |
| */ |
| if (chdir("/") < 0) { |
| fprintf(stderr, |
| "unable to change directory to %s, code %d (%s)", |
| "/", errno, strerror(errno)); |
| exit(1); |
| } |
| |
| /* Redirect standard files to /dev/null */ |
| if (!freopen("/dev/null", "r", stdin)) |
| fprintf(stderr, "unable to freopen() stdin, code %d (%s)", |
| errno, strerror(errno)); |
| |
| if (!freopen("/dev/null", "w", stdout)) |
| fprintf(stderr, "unable to freopen() stdout, code %d (%s)", |
| errno, strerror(errno)); |
| |
| if (!freopen("/dev/null", "w", stderr)) |
| fprintf(stderr, "unable to freopen() stderr, code %d (%s)", |
| errno, strerror(errno)); |
| |
| /* Tell the parent process that we are A-okay */ |
| kill(parent, SIGUSR1); |
| |
| act.sa_handler = lws_daemon_closing; |
| sigemptyset(&act.sa_mask); |
| act.sa_flags = 0; |
| |
| sigaction(SIGTERM, &act, NULL); |
| |
| /* return to continue what is now "the daemon" */ |
| |
| return 0; |
| } |
| |