daemonize module
authorRusty Russell <rusty@rustcorp.com.au>
Wed, 15 Apr 2009 02:47:28 +0000 (12:17 +0930)
committerRusty Russell <rusty@rustcorp.com.au>
Wed, 15 Apr 2009 02:47:28 +0000 (12:17 +0930)
ccan/daemonize/_info.c [new file with mode: 0644]
ccan/daemonize/daemonize.c [new file with mode: 0644]
ccan/daemonize/daemonize.h [new file with mode: 0644]

diff --git a/ccan/daemonize/_info.c b/ccan/daemonize/_info.c
new file mode 100644 (file)
index 0000000..2bdcaa9
--- /dev/null
@@ -0,0 +1,54 @@
+#include <stdio.h>
+#include <string.h>
+#include "config.h"
+
+/**
+ * daemonize - routine to turn a process into a well-behaved daemon.
+ *
+ * Daemons should detach themselves thoroughly from the process which launched
+ * them, and not prevent any filesystems from being unmounted.  daemonize()
+ * helps with the process.
+ *
+ * Example:
+ *     #include <ccan/daemonize/daemonize.h>
+ *     #include <ccan/str/str.h>
+ *     #include <err.h>
+ *     #include <unistd.h>
+ *     #include <stdlib.h>
+ *     
+ *     static void usage(const char *name)
+ *     {
+ *             errx(1, "Usage: %s [--daemonize]\n", name);
+ *     }
+ *     
+ *     // Wait for a minute, possibly as a daemon.
+ *     int main(int argc, char *argv[])
+ *     {
+ *             if (argc != 1) {
+ *                     if (argc == 2 && streq(argv[1], "--daemonize")) {
+ *                             if (!daemonize())
+ *                                     err(1, "Failed to become daemon");
+ *                     } else
+ *                             usage(argv[1]);
+ *             }
+ *             sleep(60);
+ *             exit(0);
+ *     }
+ *
+ * Licence: BSD (2 clause, ie. MIT)
+ */
+int main(int argc, char *argv[])
+{
+       if (argc != 2)
+               return 1;
+
+       if (strcmp(argv[1], "depends") == 0) {
+               return 0;
+       }
+
+       if (strcmp(argv[1], "libs") == 0) {
+               return 0;
+       }
+
+       return 1;
+}
diff --git a/ccan/daemonize/daemonize.c b/ccan/daemonize/daemonize.c
new file mode 100644 (file)
index 0000000..861b0fc
--- /dev/null
@@ -0,0 +1,31 @@
+#include <ccan/daemonize/daemonize.h>
+#include <unistd.h>
+#include <stdlib.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+
+/* This code is based on Stevens Advanced Programming in the UNIX
+ * Environment. */
+bool daemonize(void)
+{
+       pid_t pid;
+
+       /* Separate from our parent via fork, so init inherits us. */
+       if ((pid = fork()) < 0)
+               return false;
+       if (pid != 0)
+               exit(0);
+
+       /* Don't hold files open. */
+       close(STDIN_FILENO);
+       close(STDOUT_FILENO);
+       close(STDERR_FILENO);
+
+       /* Session leader so ^C doesn't whack us. */
+       setsid();
+       /* Move off any mount points we might be in. */
+       chdir("/");
+       /* Discard our parent's old-fashioned umask prejudices. */
+       umask(0);
+       return true;
+}
diff --git a/ccan/daemonize/daemonize.h b/ccan/daemonize/daemonize.h
new file mode 100644 (file)
index 0000000..cc425a4
--- /dev/null
@@ -0,0 +1,19 @@
+#ifndef CCAN_DAEMONIZE_H
+#define CCAN_DAEMONIZE_H
+#include <stdbool.h>
+
+/**
+ * daemonize - turn this process into a daemon.
+ *
+ * This routine forks us off to become a daemon.  It returns false on failure
+ * (ie. fork() failed) and sets errno.
+ *
+ * Side effects for programmers to be aware of:
+ *  - PID changes (our parent exits, we become child of init)
+ *  - stdin, stdout and stderr file descriptors are closed
+ *  - Current working directory changes to /
+ *  - Umask is set to 0.
+ */
+bool daemonize(void);
+
+#endif /* CCAN_DAEMONIZE_H */