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include daemonization file whoops
Signed-off-by: Andy Green <andy.green@linaro.org>
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lib/daemonize.c
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151
lib/daemonize.c
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/*
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* This code is mainly taken from Doug Potter's page
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*
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* http://www-theorie.physik.unizh.ch/~dpotter/howto/daemonize
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*
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* I contacted him 2007-04-16 about the license for the original code,
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* he replied it is Public Domain. Use the URL above to get the original
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* Public Domain version if you want it.
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*
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* This version is LGPL2 and is (c)2006 - 2013 Andy Green <andy@warmcat.com>
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*/
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#include <stdlib.h>
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#include <string.h>
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#include <stdio.h>
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#include <signal.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <limits.h>
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#include <unistd.h>
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#include <errno.h>
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static int pid_daemon;
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static char lock_path[PATH_MAX];
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static void child_handler(int signum)
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{
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int fd;
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char sz[20];
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switch (signum) {
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case SIGALRM: /* timedout daemonizing */
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exit(1);
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break;
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case SIGUSR1: /* positive confirmation we daemonized well */
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/* Create the lock file as the current user */
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fd = open(lock_path, O_TRUNC | O_RDWR | O_CREAT, 0640);
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if (fd < 0) {
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fprintf(stderr, "unable to create lock"
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" file %s, code=%d (%s)",
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lock_path, errno, strerror(errno));
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exit(1);
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}
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sprintf(sz, "%u", pid_daemon);
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write(fd, sz, strlen(sz));
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close(fd);
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exit(0);
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case SIGCHLD: /* daemonization failed */
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exit(1);
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break;
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}
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}
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/*
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* You just need to call this from your main(), when it
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* returns you are all set "in the background" decoupled
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* from the console you were started from.
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*
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* The process context you called from has been terminated then.
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*/
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int lws_daemonize(const char *_lock_path)
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{
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pid_t sid, parent;
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/* already a daemon */
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if (getppid() == 1)
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return (1);
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strncpy(lock_path, _lock_path, sizeof lock_path);
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lock_path[sizeof(lock_path) - 1] = '\0';
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/* Trap signals that we expect to recieve */
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signal(SIGCHLD, child_handler); /* died */
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signal(SIGUSR1, child_handler); /* was happy */
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signal(SIGALRM, child_handler); /* timeout daemonizing */
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/* Fork off the parent process */
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pid_daemon = fork();
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if (pid_daemon < 0) {
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fprintf(stderr, "unable to fork daemon, code=%d (%s)",
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errno, strerror(errno));
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exit(1);
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}
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/* If we got a good PID, then we can exit the parent process. */
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if (pid_daemon > 0) {
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/*
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* Wait for confirmation signal from the child via
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* SIGCHILD / USR1, or for two seconds to elapse
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* (SIGALRM). pause() should not return.
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*/
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alarm(2);
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pause();
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/* should not be reachable */
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exit(1);
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}
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/* At this point we are executing as the child process */
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parent = getppid();
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/* Cancel certain signals */
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signal(SIGCHLD, SIG_DFL); /* A child process dies */
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signal(SIGTSTP, SIG_IGN); /* Various TTY signals */
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signal(SIGTTOU, SIG_IGN);
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signal(SIGTTIN, SIG_IGN);
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signal(SIGHUP, SIG_IGN); /* Ignore hangup signal */
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/* Change the file mode mask */
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umask(0);
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/* Create a new SID for the child process */
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sid = setsid();
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if (sid < 0) {
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fprintf(stderr,
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"unable to create a new session, code %d (%s)",
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errno, strerror(errno));
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exit(1);
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}
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/*
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* Change the current working directory. This prevents the current
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* directory from being locked; hence not being able to remove it.
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*/
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if ((chdir("/")) < 0) {
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fprintf(stderr,
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"unable to change directory to %s, code %d (%s)",
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"/", errno, strerror(errno));
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exit(1);
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}
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/* Redirect standard files to /dev/null */
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freopen("/dev/null", "r", stdin);
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freopen("/dev/null", "w", stdout);
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freopen("/dev/null", "w", stderr);
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/* Tell the parent process that we are A-okay */
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kill(parent, SIGUSR1);
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/* return to continue what is now "the daemon" */
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return (0);
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}
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