#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)
int pid_fd;
};
+/** Flags passed to the daemon helper. **/
enum daemon_flags {
DAEMON_FLAG_PRESERVE_CWD = 1, // Skip chdir("/")
};
+/**
+ * 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.
+ **/
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,
+ 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
+ *
+ * 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)
+ **/
+enum daemon_control_status daemon_control(struct daemon_control_params *dc);
+
+enum daemon_control_status {
+ DAEMON_STATUS_OK = 0,
+ DAEMON_STATUS_ALREADY_DONE = 100,
+ DAEMON_STATUS_NOT_RUNNING = 101,
+ DAEMON_STATUS_ERROR = 102,
+};
+
#endif