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131 lines
4.4 KiB
131 lines
4.4 KiB
/*
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* UCW Library -- Daemonization
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*
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* (c) 2012--2014 Martin Mares <mj@ucw.cz>
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*
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* This software may be freely distributed and used according to the terms
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* of the GNU Lesser General Public License.
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*/
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#ifndef _UCW_DAEMON_H
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#define _UCW_DAEMON_H
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#include <sys/types.h>
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#ifdef CONFIG_UCW_CLEAN_ABI
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#define daemon_control ucw_daemon_control
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#define daemon_exit ucw_daemon_exit
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#define daemon_init ucw_daemon_init
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#define daemon_resolve_ugid ucw_daemon_resolve_ugid
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#define daemon_run ucw_daemon_run
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#define daemon_switch_ugid ucw_daemon_switch_ugid
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#endif
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/** Parameters passed to the daemon helper. **/
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struct daemon_params {
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uint flags; // DAEMON_FLAG_xxx
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const char *pid_file; // A path to PID file (optional)
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const char *run_as_user; // User name or "#uid" (optional)
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const char *run_as_group; // Group name or "#gid" (optional)
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// Internal
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uid_t run_as_uid;
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uid_t run_as_gid;
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int want_setuid;
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int want_setgid;
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int pid_fd;
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};
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/** Flags passed to the daemon helper. **/
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enum daemon_flags {
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DAEMON_FLAG_PRESERVE_CWD = 1, // Skip chdir("/")
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DAEMON_FLAG_SIMULATE = 2, // Simulate daemonization (avoid fork etc.)
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};
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/**
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* Daemon initialization. Should be run after parsing of options.
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* It resolves the UID and GID to run with and locks the PID file.
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* Upon error, it calls @die().
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**/
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void daemon_init(struct daemon_params *dp);
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/**
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* Run the daemon. Should be run when everything is initialized. It forks off
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* a new process and does all necessary setup. Inside the new process, it calls
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* @body (and when it returns, it exits the process). In the original process, it writes
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* the PID file and returns.
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*
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* When `DAEMON_FLAG_SIMULATE` is set, it justs calls @body. This is useful
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* for running of daemons in a debugger.
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**/
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void daemon_run(struct daemon_params *dp, void (*body)(struct daemon_params *dp));
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/**
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* Clean up when the daemon is about to exit. It removes the PID file.
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**/
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void daemon_exit(struct daemon_params *dp);
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/**
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* Parse `run_as_user` and `run_as_group` and remember the results in internal fields.
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* This is called automatically by daemon_init(), but also provided as a separate
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* function in case you want to use daemon_switch_ugid(). Upon parse error, it calls die().
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**/
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void daemon_resolve_ugid(struct daemon_params *dp);
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/**
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* Switch user and group as specified by the `run_as_user` and `run_as_group`.
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* This is performed automatically by daemon_run(), but sometimes you might want to
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* switch the user and group separately. In this case, you have to call daemon_resolve_ugid()
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* beforehand.
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**/
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void daemon_switch_ugid(struct daemon_params *dp);
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#define DAEMON_ERR_LEN 256
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/** Parameters passed to @daemon_control() **/
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struct daemon_control_params {
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const char *pid_file; // A path to PID file
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const char *guard_file; // A path to guard file
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int action; // Action to perform (DAEMON_CONTROL_xxx)
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char * const *argv; // Daemon's arguments, NULL-terminated (for DAEMON_CONTROL_START)
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int signal; // Signal to send (for DAEMON_CONTROL_SIGNAL)
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char error_msg[DAEMON_ERR_LEN]; // A detailed error message returned (for DAEMON_STATUS_ERROR)
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};
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enum daemon_control_action {
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DAEMON_CONTROL_CHECK = 1,
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DAEMON_CONTROL_START,
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DAEMON_CONTROL_STOP,
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DAEMON_CONTROL_SIGNAL,
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};
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/**
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* Perform an action on a daemon:
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*
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* * `DAEMON_CONTROL_START` to start the daemon
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* * `DAEMON_CONTROL_STOP` to stop the daemon (send `SIGTERM` or `dc->signal` if non-zero)
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* * `DAEMON_CONTROL_CHECK` to check that the daemon is running
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* * `DAEMON_CONTROL_SIGNAL` to send a signal to the daemon (send `SIGHUP` or `dc->signal` if non-zero)
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*
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* The function returns a status code:
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*
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* * `DAEMON_STATUS_OK` if the action has been performed successfully
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* * `DAEMON_STATUS_ALREADY_DONE` if the daemon is already in the requested state
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* * `DAEMON_STATUS_NOT_RUNNING` if the action failed, because the daemon is not running
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* * `DAEMON_STATUS_ERROR` if the action failed for some other reason (in this case,
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* `dc->error_msg` contains a full error message)
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* * `DAEMON_STATUS_STALE` if the daemon was in an undefined state (e.g., a stale PID file);
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* for `DAEMON_CONTROL_START`, it means success
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**/
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enum daemon_control_status daemon_control(struct daemon_control_params *dc);
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// XXX: Also used as exit codes of the ucw-daemon-control utility.
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enum daemon_control_status {
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DAEMON_STATUS_OK = 0,
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DAEMON_STATUS_ALREADY_DONE = 100,
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DAEMON_STATUS_NOT_RUNNING = 101,
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DAEMON_STATUS_ERROR = 102,
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DAEMON_STATUS_STALE = 103,
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};
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#endif
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