src/systemd/sd-daemon.h - systemd - Git at Google

 /* SPDX-License-Identifier: LGPL-2.1-or-later */
 #ifndef foosddaemonhfoo
 #define foosddaemonhfoo

 /***
   systemd is free software; you can redistribute it and/or modify it
   under the terms of the GNU Lesser General Public License as published by
   the Free Software Foundation; either version 2.1 of the License, or
   (at your option) any later version.

   systemd is distributed in the hope that it will be useful, but
   WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with systemd; If not, see <https://www.gnu.org/licenses/>.
 ***/

 #include <inttypes.h>
 #include <sys/types.h>
 #include <sys/socket.h>

 #include "_sd-common.h"

 _SD_BEGIN_DECLARATIONS;

 /*
   The following functionality is provided:

   - Support for logging with log levels on stderr
   - File descriptor passing for socket-based activation
   - Daemon startup and status notification
   - Detection of systemd boots

   See sd-daemon(3) for more information.
 */

 /*
   Log levels for usage on stderr:

           fprintf(stderr, SD_NOTICE "Hello World!\n");

   This is similar to printk() usage in the kernel.
 */
 #define SD_EMERG   "<0>"  /* system is unusable */
 #define SD_ALERT   "<1>"  /* action must be taken immediately */
 #define SD_CRIT    "<2>"  /* critical conditions */
 #define SD_ERR     "<3>"  /* error conditions */
 #define SD_WARNING "<4>"  /* warning conditions */
 #define SD_NOTICE  "<5>"  /* normal but significant condition */
 #define SD_INFO    "<6>"  /* informational */
 #define SD_DEBUG   "<7>"  /* debug-level messages */

 /* The first passed file descriptor is fd 3 */
 #define SD_LISTEN_FDS_START 3

 /*
   Returns how many file descriptors have been passed, or a negative
   errno code on failure. Optionally, removes the $LISTEN_FDS and
   $LISTEN_PID file descriptors from the environment (recommended, but
   problematic in threaded environments). If r is the return value of
   this function you'll find the file descriptors passed as fds
   SD_LISTEN_FDS_START to SD_LISTEN_FDS_START+r-1. Returns a negative
   errno style error code on failure. This function call ensures that
   the FD_CLOEXEC flag is set for the passed file descriptors, to make
   sure they are not passed on to child processes. If FD_CLOEXEC shall
   not be set, the caller needs to unset it after this call for all file
   descriptors that are used.

   See sd_listen_fds(3) for more information.
 */
 int sd_listen_fds(int unset_environment);

 int sd_listen_fds_with_names(int unset_environment, char ***names);

 /*
   Helper call for identifying a passed file descriptor. Returns 1 if
   the file descriptor is a FIFO in the file system stored under the
   specified path, 0 otherwise. If path is NULL a path name check will
   not be done and the call only verifies if the file descriptor
   refers to a FIFO. Returns a negative errno style error code on
   failure.

   See sd_is_fifo(3) for more information.
 */
 int sd_is_fifo(int fd, const char *path);

 /*
   Helper call for identifying a passed file descriptor. Returns 1 if
   the file descriptor is a special character device on the file
   system stored under the specified path, 0 otherwise.
   If path is NULL a path name check will not be done and the call
   only verifies if the file descriptor refers to a special character.
   Returns a negative errno style error code on failure.

   See sd_is_special(3) for more information.
 */
 int sd_is_special(int fd, const char *path);

 /*
   Helper call for identifying a passed file descriptor. Returns 1 if
   the file descriptor is a socket of the specified family (AF_INET,
   ...) and type (SOCK_DGRAM, SOCK_STREAM, ...), 0 otherwise. If
   family is 0 a socket family check will not be done. If type is 0 a
   socket type check will not be done and the call only verifies if
   the file descriptor refers to a socket. If listening is > 0 it is
   verified that the socket is in listening mode. (i.e. listen() has
   been called) If listening is == 0 it is verified that the socket is
   not in listening mode. If listening is < 0 no listening mode check
   is done. Returns a negative errno style error code on failure.

   See sd_is_socket(3) for more information.
 */
 int sd_is_socket(int fd, int family, int type, int listening);

 /*
   Helper call for identifying a passed file descriptor. Returns 1 if
   the file descriptor is an Internet socket, of the specified family
   (either AF_INET or AF_INET6) and the specified type (SOCK_DGRAM,
   SOCK_STREAM, ...), 0 otherwise. If version is 0 a protocol version
   check is not done. If type is 0 a socket type check will not be
   done. If port is 0 a socket port check will not be done. The
   listening flag is used the same way as in sd_is_socket(). Returns a
   negative errno style error code on failure.

   See sd_is_socket_inet(3) for more information.
 */
 int sd_is_socket_inet(int fd, int family, int type, int listening, uint16_t port);

 /*
   Helper call for identifying a passed file descriptor. Returns 1 if the
   file descriptor is an Internet socket of the specified type
   (SOCK_DGRAM, SOCK_STREAM, ...), and if the address of the socket is
   the same as the address specified by addr. The listening flag is used
   the same way as in sd_is_socket(). Returns a negative errno style
   error code on failure.

   See sd_is_socket_sockaddr(3) for more information.
 */
 int sd_is_socket_sockaddr(int fd, int type, const struct sockaddr* addr, unsigned addr_len, int listening);

 /*
   Helper call for identifying a passed file descriptor. Returns 1 if
   the file descriptor is an AF_UNIX socket of the specified type
   (SOCK_DGRAM, SOCK_STREAM, ...) and path, 0 otherwise. If type is 0
   a socket type check will not be done. If path is NULL a socket path
   check will not be done. For normal AF_UNIX sockets set length to
   0. For abstract namespace sockets set length to the length of the
   socket name (including the initial 0 byte), and pass the full
   socket path in path (including the initial 0 byte). The listening
   flag is used the same way as in sd_is_socket(). Returns a negative
   errno style error code on failure.

   See sd_is_socket_unix(3) for more information.
 */
 int sd_is_socket_unix(int fd, int type, int listening, const char *path, size_t length);

 /*
   Helper call for identifying a passed file descriptor. Returns 1 if
   the file descriptor is a POSIX Message Queue of the specified name,
   0 otherwise. If path is NULL a message queue name check is not
   done. Returns a negative errno style error code on failure.

   See sd_is_mq(3) for more information.
 */
 int sd_is_mq(int fd, const char *path);

 /*
   Informs systemd about changed daemon state. This takes a number of
   newline separated environment-style variable assignments in a
   string. The following variables are known:

      MAINPID=...  The main PID of a daemon, in case systemd did not
                   fork off the process itself. Example: "MAINPID=4711"

      READY=1      Tells systemd that daemon startup or daemon reload
                   is finished (only relevant for services of Type=notify).
                   The passed argument is a boolean "1" or "0". Since there
                   is little value in signaling non-readiness the only
                   value daemons should send is "READY=1".

      RELOADING=1  Tell systemd that the daemon began reloading its
                   configuration. When the configuration has been
                   reloaded completely, READY=1 should be sent to inform
                   systemd about this.

      STOPPING=1   Tells systemd that the daemon is about to go down.

      STATUS=...   Passes a single-line status string back to systemd
                   that describes the daemon state. This is free-form
                   and can be used for various purposes: general state
                   feedback, fsck-like programs could pass completion
                   percentages and failing programs could pass a human
                   readable error message. Example: "STATUS=Completed
                   66% of file system check..."

      ERRNO=...    If a daemon fails, the errno-style error code,
                   formatted as string. Example: "ERRNO=2" for ENOENT.

      BUSERROR=... If a daemon fails, the D-Bus error-style error
                   code. Example: "BUSERROR=org.freedesktop.DBus.Error.TimedOut"

      WATCHDOG=1   Tells systemd to update the watchdog timestamp.
                   Services using this feature should do this in
                   regular intervals. A watchdog framework can use the
                   timestamps to detect failed services. Also see
                   sd_watchdog_enabled() below.

      WATCHDOG_USEC=...
                   Reset watchdog_usec value during runtime.
                   To reset watchdog_usec value, start the service again.
                   Example: "WATCHDOG_USEC=20000000"

      FDSTORE=1    Store the file descriptors passed along with the
                   message in the per-service file descriptor store,
                   and pass them to the main process again on next
                   invocation. This variable is only supported with
                   sd_pid_notify_with_fds().

      FDSTOREREMOVE=1
                   Remove one or more file descriptors from the file
                   descriptor store, identified by the name specified
                   in FDNAME=, see below.

      FDNAME=      A name to assign to new file descriptors stored in the
                   file descriptor store, or the name of the file descriptors
                   to remove in case of FDSTOREREMOVE=1.

   Daemons can choose to send additional variables. However, it is
   recommended to prefix variable names not listed above with X_.

   Returns a negative errno-style error code on failure. Returns > 0
   if systemd could be notified, 0 if it couldn't possibly because
   systemd is not running.

   Example: When a daemon finished starting up, it could issue this
   call to notify systemd about it:

      sd_notify(0, "READY=1");

   See sd_notifyf() for more complete examples.

   See sd_notify(3) for more information.
 */
 int sd_notify(int unset_environment, const char *state);

 /*
   Similar to sd_notify() but takes a format string.

   Example 1: A daemon could send the following after initialization:

      sd_notifyf(0, "READY=1\n"
                    "STATUS=Processing requests...\n"
                    "MAINPID=%lu",
                    (unsigned long) getpid());

   Example 2: A daemon could send the following shortly before
   exiting, on failure:

      sd_notifyf(0, "STATUS=Failed to start up: %s\n"
                    "ERRNO=%i",
                    strerror_r(errnum, (char[1024]){}, 1024),
                    errnum);

   See sd_notifyf(3) for more information.
 */
 int sd_notifyf(int unset_environment, const char *format, ...) _sd_printf_(2,3);

 /*
   Similar to sd_notify(), but send the message on behalf of another
   process, if the appropriate permissions are available.
 */
 int sd_pid_notify(pid_t pid, int unset_environment, const char *state);

 /*
   Similar to sd_notifyf(), but send the message on behalf of another
   process, if the appropriate permissions are available.
 */
 int sd_pid_notifyf(pid_t pid, int unset_environment, const char *format, ...) _sd_printf_(3,4);

 /*
   Similar to sd_pid_notify(), but also passes the specified fd array
   to the service manager for storage. This is particularly useful for
   FDSTORE=1 messages.
 */
 int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char *state, const int *fds, unsigned n_fds);

 /*
   Returns > 0 if synchronization with systemd succeeded.  Returns < 0
   on error. Returns 0 if $NOTIFY_SOCKET was not set. Note that the
   timeout parameter of this function call takes the timeout in µs, and
   will be passed to ppoll(2), hence the behaviour will be similar to
   ppoll(2). This function can be called after sending a status message
   to systemd, if one needs to synchronize against reception of the
   status messages sent before this call is made. Therefore, this
   cannot be used to know if the status message was processed
   successfully, but to only synchronize against its consumption.
 */
 int sd_notify_barrier(int unset_environment, uint64_t timeout);

 /*
   Returns > 0 if the system was booted with systemd. Returns < 0 on
   error. Returns 0 if the system was not booted with systemd. Note
   that all of the functions above handle non-systemd boots just
   fine. You should NOT protect them with a call to this function. Also
   note that this function checks whether the system, not the user
   session is controlled by systemd. However the functions above work
   for both user and system services.

   See sd_booted(3) for more information.
 */
 int sd_booted(void);

 /*
   Returns > 0 if the service manager expects watchdog keep-alive
   events to be sent regularly via sd_notify(0, "WATCHDOG=1"). Returns
   0 if it does not expect this. If the usec argument is non-NULL
   returns the watchdog timeout in µs after which the service manager
   will act on a process that has not sent a watchdog keep alive
   message. This function is useful to implement services that
   recognize automatically if they are being run under supervision of
   systemd with WatchdogSec= set. It is recommended for clients to
   generate keep-alive pings via sd_notify(0, "WATCHDOG=1") every half
   of the returned time.

   See sd_watchdog_enabled(3) for more information.
 */
 int sd_watchdog_enabled(int unset_environment, uint64_t *usec);

 _SD_END_DECLARATIONS;

 #endif
	/* SPDX-License-Identifier: LGPL-2.1-or-later */
	#ifndef foosddaemonhfoo
	#define foosddaemonhfoo

	/***
	systemd is free software; you can redistribute it and/or modify it
	under the terms of the GNU Lesser General Public License as published by
	the Free Software Foundation; either version 2.1 of the License, or
	(at your option) any later version.

	systemd is distributed in the hope that it will be useful, but
	WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
	Lesser General Public License for more details.

	You should have received a copy of the GNU Lesser General Public License
	along with systemd; If not, see <https://www.gnu.org/licenses/>.
	***/

	#include <inttypes.h>
	#include <sys/types.h>
	#include <sys/socket.h>

	#include "_sd-common.h"

	_SD_BEGIN_DECLARATIONS;

	/*
	The following functionality is provided:

	- Support for logging with log levels on stderr
	- File descriptor passing for socket-based activation
	- Daemon startup and status notification
	- Detection of systemd boots

	See sd-daemon(3) for more information.
	*/

	/*
	Log levels for usage on stderr:

	fprintf(stderr, SD_NOTICE "Hello World!\n");

	This is similar to printk() usage in the kernel.
	*/
	#define SD_EMERG "<0>" /* system is unusable */
	#define SD_ALERT "<1>" /* action must be taken immediately */
	#define SD_CRIT "<2>" /* critical conditions */
	#define SD_ERR "<3>" /* error conditions */
	#define SD_WARNING "<4>" /* warning conditions */
	#define SD_NOTICE "<5>" /* normal but significant condition */
	#define SD_INFO "<6>" /* informational */
	#define SD_DEBUG "<7>" /* debug-level messages */

	/* The first passed file descriptor is fd 3 */
	#define SD_LISTEN_FDS_START 3

	/*
	Returns how many file descriptors have been passed, or a negative
	errno code on failure. Optionally, removes the $LISTEN_FDS and
	$LISTEN_PID file descriptors from the environment (recommended, but
	problematic in threaded environments). If r is the return value of
	this function you'll find the file descriptors passed as fds
	SD_LISTEN_FDS_START to SD_LISTEN_FDS_START+r-1. Returns a negative
	errno style error code on failure. This function call ensures that
	the FD_CLOEXEC flag is set for the passed file descriptors, to make
	sure they are not passed on to child processes. If FD_CLOEXEC shall
	not be set, the caller needs to unset it after this call for all file
	descriptors that are used.

	See sd_listen_fds(3) for more information.
	*/
	int sd_listen_fds(int unset_environment);

	int sd_listen_fds_with_names(int unset_environment, char ***names);

	/*
	Helper call for identifying a passed file descriptor. Returns 1 if
	the file descriptor is a FIFO in the file system stored under the
	specified path, 0 otherwise. If path is NULL a path name check will
	not be done and the call only verifies if the file descriptor
	refers to a FIFO. Returns a negative errno style error code on
	failure.

	See sd_is_fifo(3) for more information.
	*/
	int sd_is_fifo(int fd, const char *path);

	/*
	Helper call for identifying a passed file descriptor. Returns 1 if
	the file descriptor is a special character device on the file
	system stored under the specified path, 0 otherwise.
	If path is NULL a path name check will not be done and the call
	only verifies if the file descriptor refers to a special character.
	Returns a negative errno style error code on failure.

	See sd_is_special(3) for more information.
	*/
	int sd_is_special(int fd, const char *path);

	/*
	Helper call for identifying a passed file descriptor. Returns 1 if
	the file descriptor is a socket of the specified family (AF_INET,
	...) and type (SOCK_DGRAM, SOCK_STREAM, ...), 0 otherwise. If
	family is 0 a socket family check will not be done. If type is 0 a
	socket type check will not be done and the call only verifies if
	the file descriptor refers to a socket. If listening is > 0 it is
	verified that the socket is in listening mode. (i.e. listen() has
	been called) If listening is == 0 it is verified that the socket is
	not in listening mode. If listening is < 0 no listening mode check
	is done. Returns a negative errno style error code on failure.

	See sd_is_socket(3) for more information.
	*/
	int sd_is_socket(int fd, int family, int type, int listening);

	/*
	Helper call for identifying a passed file descriptor. Returns 1 if
	the file descriptor is an Internet socket, of the specified family
	(either AF_INET or AF_INET6) and the specified type (SOCK_DGRAM,
	SOCK_STREAM, ...), 0 otherwise. If version is 0 a protocol version
	check is not done. If type is 0 a socket type check will not be
	done. If port is 0 a socket port check will not be done. The
	listening flag is used the same way as in sd_is_socket(). Returns a
	negative errno style error code on failure.

	See sd_is_socket_inet(3) for more information.
	*/
	int sd_is_socket_inet(int fd, int family, int type, int listening, uint16_t port);

	/*
	Helper call for identifying a passed file descriptor. Returns 1 if the
	file descriptor is an Internet socket of the specified type
	(SOCK_DGRAM, SOCK_STREAM, ...), and if the address of the socket is
	the same as the address specified by addr. The listening flag is used
	the same way as in sd_is_socket(). Returns a negative errno style
	error code on failure.

	See sd_is_socket_sockaddr(3) for more information.
	*/
	int sd_is_socket_sockaddr(int fd, int type, const struct sockaddr* addr, unsigned addr_len, int listening);

	/*
	Helper call for identifying a passed file descriptor. Returns 1 if
	the file descriptor is an AF_UNIX socket of the specified type
	(SOCK_DGRAM, SOCK_STREAM, ...) and path, 0 otherwise. If type is 0
	a socket type check will not be done. If path is NULL a socket path
	check will not be done. For normal AF_UNIX sockets set length to
	0. For abstract namespace sockets set length to the length of the
	socket name (including the initial 0 byte), and pass the full
	socket path in path (including the initial 0 byte). The listening
	flag is used the same way as in sd_is_socket(). Returns a negative
	errno style error code on failure.

	See sd_is_socket_unix(3) for more information.
	*/
	int sd_is_socket_unix(int fd, int type, int listening, const char *path, size_t length);

	/*
	Helper call for identifying a passed file descriptor. Returns 1 if
	the file descriptor is a POSIX Message Queue of the specified name,
	0 otherwise. If path is NULL a message queue name check is not
	done. Returns a negative errno style error code on failure.

	See sd_is_mq(3) for more information.
	*/
	int sd_is_mq(int fd, const char *path);

	/*
	Informs systemd about changed daemon state. This takes a number of
	newline separated environment-style variable assignments in a
	string. The following variables are known:

	MAINPID=... The main PID of a daemon, in case systemd did not
	fork off the process itself. Example: "MAINPID=4711"

	READY=1 Tells systemd that daemon startup or daemon reload
	is finished (only relevant for services of Type=notify).
	The passed argument is a boolean "1" or "0". Since there
	is little value in signaling non-readiness the only
	value daemons should send is "READY=1".

	RELOADING=1 Tell systemd that the daemon began reloading its
	configuration. When the configuration has been
	reloaded completely, READY=1 should be sent to inform
	systemd about this.

	STOPPING=1 Tells systemd that the daemon is about to go down.

	STATUS=... Passes a single-line status string back to systemd
	that describes the daemon state. This is free-form
	and can be used for various purposes: general state
	feedback, fsck-like programs could pass completion
	percentages and failing programs could pass a human
	readable error message. Example: "STATUS=Completed
	66% of file system check..."

	ERRNO=... If a daemon fails, the errno-style error code,
	formatted as string. Example: "ERRNO=2" for ENOENT.

	BUSERROR=... If a daemon fails, the D-Bus error-style error
	code. Example: "BUSERROR=org.freedesktop.DBus.Error.TimedOut"

	WATCHDOG=1 Tells systemd to update the watchdog timestamp.
	Services using this feature should do this in
	regular intervals. A watchdog framework can use the
	timestamps to detect failed services. Also see
	sd_watchdog_enabled() below.

	WATCHDOG_USEC=...
	Reset watchdog_usec value during runtime.
	To reset watchdog_usec value, start the service again.
	Example: "WATCHDOG_USEC=20000000"

	FDSTORE=1 Store the file descriptors passed along with the
	message in the per-service file descriptor store,
	and pass them to the main process again on next
	invocation. This variable is only supported with
	sd_pid_notify_with_fds().

	FDSTOREREMOVE=1
	Remove one or more file descriptors from the file
	descriptor store, identified by the name specified
	in FDNAME=, see below.

	FDNAME= A name to assign to new file descriptors stored in the
	file descriptor store, or the name of the file descriptors
	to remove in case of FDSTOREREMOVE=1.

	Daemons can choose to send additional variables. However, it is
	recommended to prefix variable names not listed above with X_.

	Returns a negative errno-style error code on failure. Returns > 0
	if systemd could be notified, 0 if it couldn't possibly because
	systemd is not running.

	Example: When a daemon finished starting up, it could issue this
	call to notify systemd about it:

	sd_notify(0, "READY=1");

	See sd_notifyf() for more complete examples.

	See sd_notify(3) for more information.
	*/
	int sd_notify(int unset_environment, const char *state);

	/*
	Similar to sd_notify() but takes a format string.

	Example 1: A daemon could send the following after initialization:

	sd_notifyf(0, "READY=1\n"
	"STATUS=Processing requests...\n"
	"MAINPID=%lu",
	(unsigned long) getpid());

	Example 2: A daemon could send the following shortly before
	exiting, on failure:

	sd_notifyf(0, "STATUS=Failed to start up: %s\n"
	"ERRNO=%i",
	strerror_r(errnum, (char[1024]){}, 1024),
	errnum);

	See sd_notifyf(3) for more information.
	*/
	int sd_notifyf(int unset_environment, const char *format, ...) _sd_printf_(2,3);

	/*
	Similar to sd_notify(), but send the message on behalf of another
	process, if the appropriate permissions are available.
	*/
	int sd_pid_notify(pid_t pid, int unset_environment, const char *state);

	/*
	Similar to sd_notifyf(), but send the message on behalf of another
	process, if the appropriate permissions are available.
	*/
	int sd_pid_notifyf(pid_t pid, int unset_environment, const char *format, ...) _sd_printf_(3,4);

	/*
	Similar to sd_pid_notify(), but also passes the specified fd array
	to the service manager for storage. This is particularly useful for
	FDSTORE=1 messages.
	*/
	int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char state, const int fds, unsigned n_fds);

	/*
	Returns > 0 if synchronization with systemd succeeded. Returns < 0
	on error. Returns 0 if $NOTIFY_SOCKET was not set. Note that the
	timeout parameter of this function call takes the timeout in µs, and
	will be passed to ppoll(2), hence the behaviour will be similar to
	ppoll(2). This function can be called after sending a status message
	to systemd, if one needs to synchronize against reception of the
	status messages sent before this call is made. Therefore, this
	cannot be used to know if the status message was processed
	successfully, but to only synchronize against its consumption.
	*/
	int sd_notify_barrier(int unset_environment, uint64_t timeout);

	/*
	Returns > 0 if the system was booted with systemd. Returns < 0 on
	error. Returns 0 if the system was not booted with systemd. Note
	that all of the functions above handle non-systemd boots just
	fine. You should NOT protect them with a call to this function. Also
	note that this function checks whether the system, not the user
	session is controlled by systemd. However the functions above work
	for both user and system services.

	See sd_booted(3) for more information.
	*/
	int sd_booted(void);

	/*
	Returns > 0 if the service manager expects watchdog keep-alive
	events to be sent regularly via sd_notify(0, "WATCHDOG=1"). Returns
	0 if it does not expect this. If the usec argument is non-NULL
	returns the watchdog timeout in µs after which the service manager
	will act on a process that has not sent a watchdog keep alive
	message. This function is useful to implement services that
	recognize automatically if they are being run under supervision of
	systemd with WatchdogSec= set. It is recommended for clients to
	generate keep-alive pings via sd_notify(0, "WATCHDOG=1") every half
	of the returned time.

	See sd_watchdog_enabled(3) for more information.
	*/
	int sd_watchdog_enabled(int unset_environment, uint64_t *usec);

	_SD_END_DECLARATIONS;

	#endif