2 * UCW Library -- Daemonization
4 * (c) 2012--2014 Martin Mares <mj@ucw.cz>
6 * This software may be freely distributed and used according to the terms
7 * of the GNU Lesser General Public License.
13 #include <sys/types.h>
15 #ifdef CONFIG_UCW_CLEAN_ABI
16 #define daemon_control ucw_daemon_control
17 #define daemon_exit ucw_daemon_exit
18 #define daemon_init ucw_daemon_init
19 #define daemon_run ucw_daemon_run
22 /** Parameters passed to the daemon helper. **/
23 struct daemon_params {
24 uns flags; // DAEMON_FLAG_xxx
25 const char *pid_file; // A path to PID file (optional)
26 const char *run_as_user; // User name or "#uid" (optional)
27 const char *run_as_group; // Group name or "#gid" (optional)
37 /** Flags passed to the daemon helper. **/
39 DAEMON_FLAG_PRESERVE_CWD = 1, // Skip chdir("/")
40 DAEMON_FLAG_SIMULATE = 2, // Simulate daemonization (avoid fork etc.)
44 * Daemon initialization. Should be run after parsing of options.
45 * It resolves the UID and GID to run with and locks the PID file.
46 * Upon error, it calls @die().
48 void daemon_init(struct daemon_params *dp);
51 * Run the daemon. Should be run when everything is initialized. It forks off
52 * a new process and does all necessary setup. Inside the new process, it calls
53 * @body (and when it returns, it exits the process). In the original process, it writes
54 * the PID file and returns.
56 * When `DAEMON_FLAG_SIMULATE` is set, it justs calls @body. This is useful
57 * for running of daemons in a debugger.
59 void daemon_run(struct daemon_params *dp, void (*body)(struct daemon_params *dp));
62 * Clean up when the daemon is about to exit. It removes the PID file.
64 void daemon_exit(struct daemon_params *dp);
67 * Parse `run_as_user` and `run_as_group` and remember the results in internal fields.
68 * This is called automatically by daemon_init(), but also provided as a separate
69 * function in case you want to use daemon_switch_ugid(). Upon parse error, it calls die().
71 void daemon_resolve_ugid(struct daemon_params *dp);
74 * Switch user and group as specified by the `run_as_user` and `run_as_group`.
75 * This is performed automatically by daemon_run(), but sometimes you might want to
76 * switch the user and group separately. In this case, you have to call daemon_resolve_ugid()
79 void daemon_switch_ugid(struct daemon_params *dp);
81 #define DAEMON_ERR_LEN 256
83 /** Parameters passed to @daemon_control() **/
84 struct daemon_control_params {
85 const char *pid_file; // A path to PID file
86 const char *guard_file; // A path to guard file
87 int action; // Action to perform (DAEMON_CONTROL_xxx)
88 char * const *argv; // Daemon's arguments, NULL-terminated (for DAEMON_CONTROL_START)
89 int signal; // Signal to send (for DAEMON_CONTROL_SIGNAL)
90 char error_msg[DAEMON_ERR_LEN]; // A detailed error message returned (for DAEMON_STATUS_ERROR)
93 enum daemon_control_action {
94 DAEMON_CONTROL_CHECK = 1,
97 DAEMON_CONTROL_SIGNAL,
101 * Perform an action on a daemon:
103 * * `DAEMON_CONTROL_START` to start the daemon
104 * * `DAEMON_CONTROL_STOP` to stop the daemon (send `SIGTERM` or `dc->signal` if non-zero)
105 * * `DAEMON_CONTROL_CHECK` to check that the daemon is running
106 * * `DAEMON_CONTROL_SIGNAL` to send a signal to the daemon (send `SIGHUP` or `dc->signal` if non-zero)
108 * The function returns a status code:
110 * * `DAEMON_STATUS_OK` if the action has been performed successfully
111 * * `DAEMON_STATUS_ALREADY_DONE` if the daemon is already in the requested state
112 * * `DAEMON_STATUS_NOT_RUNNING` if the action failed, because the daemon is not running
113 * * `DAEMON_STATUS_ERROR` if the action failed for some other reason (in this case,
114 * `dc->error_msg` contains a full error message)
115 * * `DAEMON_STATUS_STALE` if the daemon was in an undefined state (e.g., a stale PID file);
116 * for `DAEMON_CONTROL_START`, it means success
118 enum daemon_control_status daemon_control(struct daemon_control_params *dc);
120 // XXX: Also used as exit codes of the ucw-daemon-control utility.
121 enum daemon_control_status {
122 DAEMON_STATUS_OK = 0,
123 DAEMON_STATUS_ALREADY_DONE = 100,
124 DAEMON_STATUS_NOT_RUNNING = 101,
125 DAEMON_STATUS_ERROR = 102,
126 DAEMON_STATUS_STALE = 103,