include daemonization file whoops

Signed-off-by: Andy Green <andy.green@linaro.org>

diff --git a/lib/daemonize.c b/lib/daemonize.c
new file mode 100644 (file)
index 0000000..1d0c800
--- /dev/null
+++ 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);
+}
+