Heap: Interface cleanup

[libucw.git] / ucw / daemon.h

diff --git a/ucw/daemon.h b/ucw/daemon.h
index 13f8c37a144df01711d3a953ab50b33bdc24a888..c5beacc060ca8186171e91fad6a9ef3b3878dffa 100644 (file)
--- a/ucw/daemon.h
+++ b/ucw/daemon.h
@@ -12,6 +12,7 @@
 
 #include <sys/types.h>
 
+/** Parameters passed to the daemon helper. **/
 struct daemon_params {
   uns flags;                           // DAEMON_FLAG_xxx
   const char *pid_file;                        // A path to PID file (optional)
@@ -26,14 +27,81 @@ struct daemon_params {
   int pid_fd;
 };
 
+/** Flags passed to the daemon helper. **/
 enum daemon_flags {
   DAEMON_FLAG_PRESERVE_CWD = 1,                // Skip chdir("/")
+  DAEMON_FLAG_SIMULATE = 2,            // Simulate daemonization (avoid fork etc.)
 };
 
+/**
+ * Daemon initialization. Should be run after parsing of options.
+ * It resolves the UID and GID to run with and locks the PID file.
+ * Upon error, it calls @die().
+ **/
 void daemon_init(struct daemon_params *dp);
 
+/**
+ * Run the daemon. Should be run when everything is initialized. It forks off
+ * a new process and does all necessary setup. Inside the new process, it calls
+ * @body (and when it returns, it exits the process). In the original process, it writes
+ * the PID file and returns.
+ *
+ * When `DAEMON_FLAG_SIMULATE` is set, it justs calls @body. This is useful
+ * for running of daemons in a debugger.
+ **/
 void daemon_run(struct daemon_params *dp, void (*body)(struct daemon_params *dp));
 
+/**
+ * Clean up when the daemon is about to exit. It removes the PID file.
+ **/
 void daemon_exit(struct daemon_params *dp);
 
+#define DAEMON_ERR_LEN 256
+
+/** Parameters passed to daemon_control() **/
+struct daemon_control_params {
+  const char *pid_file;                // A path to PID file
+  const char *guard_file;      // A path to guard file
+  int action;                  // Action to perform (DAEMON_CONTROL_xxx)
+  char * const *argv;          // Daemon's arguments, NULL-terminated (for DAEMON_CONTROL_START)
+  int signal;                  // Signal to send (for DAEMON_CONTROL_SIGNAL)
+  char error_msg[DAEMON_ERR_LEN];      // A detailed error message returned (for DAEMON_STATUS_ERROR)
+};
+
+enum daemon_control_action {
+  DAEMON_CONTROL_CHECK = 1,
+  DAEMON_CONTROL_START,
+  DAEMON_CONTROL_STOP,
+  DAEMON_CONTROL_SIGNAL,
+};
+
+/**
+ * Perform an action on a daemon:
+ *
+ * * `DAEMON_CONTROL_START` to start the daemon
+ * * `DAEMON_CONTROL_STOP` to stop the daemon (send `SIGTERM` or `dc->signal` if non-zero)
+ * * `DAEMON_CONTROL_CHECK` to check that the daemon is running
+ * * `DAEMON_CONTROL_SIGNAL` to send a signal to the daemon (send `SIGHUP` or `dc->signal` if non-zero)
+ *
+ * The function returns a status code:
+ *
+ * * `DAEMON_STATUS_OK` if the action has been performed successfully
+ * * `DAEMON_STATUS_ALREADY_DONE` if the daemon is already in the requested state
+ * * `DAEMON_STATUS_NOT_RUNNING` if the action failed, because the daemon is not running
+ * * `DAEMON_STATUS_ERROR` if the action failed for some other reason (in this case,
+ *   `dc->error_msg` contains a full error message)
+ * * `DAEMON_STATUS_STALE` if the daemon was in an undefined state (e.g., a stale PID file);
+ *   for `DAEMON_CONTROL_START`, it means success
+ **/
+enum daemon_control_status daemon_control(struct daemon_control_params *dc);
+
+// XXX: Also used as exit codes of the daemon-control utility.
+enum daemon_control_status {
+  DAEMON_STATUS_OK = 0,
+  DAEMON_STATUS_ALREADY_DONE = 100,
+  DAEMON_STATUS_NOT_RUNNING = 101,
+  DAEMON_STATUS_ERROR = 102,
+  DAEMON_STATUS_STALE = 103,
+};
+
 #endif