include daemonization file whoops

Signed-off-by: Andy Green <andy.green@linaro.org>
2025-03-16 00:00:07 +01:00 · 2013-01-17 15:49:27 +08:00 · 2013-01-17 15:49:27 +08:00 · b2de95d2d4
commit b2de95d2d4
parent eff73742bc
1 changed files with 151 additions and 0 deletions
--- a/lib/daemonize.c
+++ b/lib/daemonize.c
@ -0,0 +1,151 @@
+/*
+ * 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>
+
+static int pid_daemon;
+static char lock_path[PATH_MAX];
+
+static void child_handler(int signum)
+{
+	int fd;
+	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)",
+				lock_path, errno, strerror(errno));
+			exit(1);
+		}
+		sprintf(sz, "%u", pid_daemon);
+		write(fd, sz, strlen(sz));
+		close(fd);
+		exit(0);
+
+	case SIGCHLD: /* daemonization failed */
+		exit(1);
+		break;
+	}
+}
+
+/*
+ * 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.
+ */
+
+int lws_daemonize(const char *_lock_path)
+{
+	pid_t sid, parent;
+
+	/* already a daemon */
+	if (getppid() == 1)
+		return (1);
+
+	strncpy(lock_path, _lock_path, sizeof lock_path);
+	lock_path[sizeof(lock_path) - 1] = '\0';
+
+	/* 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();
+
+	/* 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 */
+	freopen("/dev/null", "r", stdin);
+	freopen("/dev/null", "w", stdout);
+	freopen("/dev/null", "w", stderr);
+
+	/* Tell the parent process that we are A-okay */
+	kill(parent, SIGUSR1);
+
+	/* return to continue what is now "the daemon" */
+
+	return (0);
+}
+