*** /dev/null Sat Apr 27 03:30:39 2024
--- - Sat Apr 27 03:31:58 2024
***************
*** 0 ****
--- 1,120 ----
+ /*
+ ** daemon.c -- daemonize current process
+ ** Copyright (c) 1999-2000 Ralf S. Engelschall, All Rights Reserved.
+ **
+ ** See "Unix Programming Frequently Asked Questions":
+ ** http://www.erlenstar.demon.co.uk/unix/faq_2.html#SEC10
+ */
+
+ #include <fcntl.h>
+ #include <unistd.h>
+ #include <signal.h>
+ #include <sys/stat.h>
+ #include <sys/ioctl.h>
+
+ #include "daemon.h"
+
+ int daemonize(int nochdir, int noclose)
+ {
+ int fd;
+ int rc;
+
+ /*
+ * if we are started from init,
+ * no need to become daemon.
+ */
+ #if 0
+ if (getppid() == 1)
+ return;
+ #endif
+
+ /*
+ * Ignore tty related signals
+ */
+ #ifdef SIGTTOU
+ signal(SIGTTOU, SIG_IGN);
+ #endif
+ #ifdef SIGTTIN
+ signal(SIGTTIN, SIG_IGN);
+ #endif
+ #ifdef SIGTSTP
+ signal(SIGTSTP, SIG_IGN);
+ #endif
+
+ /*
+ * fork so the parent can exit, this returns control to the command line
+ * or shell invoking your program. This step is required so that the new
+ * process is guaranteed not to be a process group leader (The next step,
+ * setsid, would fail if you're a process group leader).
+ */
+ rc = fork();
+ switch (rc) {
+ case -1: return -1;
+ case 0: break;
+ default: _exit(0); /* exit original process */
+ }
+
+ /*
+ * setsid to become a process group and session group leader. Since a
+ * controlling terminal is associated with a session, and this new session
+ * has not yet acquired a controlling terminal our process now has no
+ * controlling terminal, which is a Good Thing for daemons.
+ */
+ #ifdef HAVE_SETSID
+ if (setsid() == -1)
+ return -1;
+ #else
+ if (setpgid(0, getpid()) == -1)
+ return -1;
+ #ifndef _PATH_TTY
+ #define _PATH_TTY "/dev/tty"
+ #endif
+ if ((fd = open(_PATH_TTY, O_RDWR)) == -1)
+ return -1;
+ ioctl(fd, TIOCNOTTY, NULL);
+ close(fd);
+ #endif
+
+ /*
+ * fork again so the parent, (the session group leader), can exit. This
+ * means that we, as a non-session group leader, can never regain a
+ * controlling terminal.
+ */
+ rc = fork();
+ switch (rc) {
+ case -1: return -1;
+ case 0: break;
+ default: _exit(0); /* exit original process */
+ }
+
+ /*
+ * chdir("/") to ensure that our process doesn't keep any directory in
+ * use. Failure to do this could make it so that an administrator couldn't
+ * unmount a filesystem, because it was our current directory.
+ * [Equivalently, we could change to any directory containing files
+ * important to the daemon's operation.]
+ */
+ if (!nochdir)
+ chdir("/");
+
+ /*
+ * give us complete control over the permissions of anything we write. We
+ * don't know what umask we may have inherited. [This step is optional]
+ */
+ umask(0);
+
+ /*
+ * close fds 0, 1, and 2. This releases the standard in, out, and error we
+ * inherited from our parent process. We have no way of knowing where
+ * these fds might have been redirected to.
+ */
+ if (!noclose && (fd = open("/dev/null", O_RDWR, 0)) != -1) {
+ dup2(fd, STDIN_FILENO);
+ dup2(fd, STDOUT_FILENO);
+ dup2(fd, STDERR_FILENO);
+ if (fd > 2)
+ close(fd);
+ }
+ return 0;
+ }
+
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