1 /* SPDX-License-Identifier: LGPL-2.1+ */
2 #ifndef foosddaemonhfoo
3 #define foosddaemonhfoo
6 This file is part of systemd.
8 Copyright 2013 Lennart Poettering
10 systemd is free software; you can redistribute it and/or modify it
11 under the terms of the GNU Lesser General Public License as published by
12 the Free Software Foundation; either version 2.1 of the License, or
13 (at your option) any later version.
15 systemd is distributed in the hope that it will be useful, but
16 WITHOUT ANY WARRANTY; without even the implied warranty of
17 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
18 Lesser General Public License for more details.
20 You should have received a copy of the GNU Lesser General Public License
21 along with systemd; If not, see <http://www.gnu.org/licenses/>.
25 #include <sys/types.h>
26 #include <sys/socket.h>
28 #include "_sd-common.h"
30 _SD_BEGIN_DECLARATIONS;
33 The following functionality is provided:
35 - Support for logging with log levels on stderr
36 - File descriptor passing for socket-based activation
37 - Daemon startup and status notification
38 - Detection of systemd boots
40 See sd-daemon(3) for more information.
44 Log levels for usage on stderr:
46 fprintf(stderr, SD_NOTICE "Hello World!\n");
48 This is similar to printk() usage in the kernel.
50 #define SD_EMERG "<0>" /* system is unusable */
51 #define SD_ALERT "<1>" /* action must be taken immediately */
52 #define SD_CRIT "<2>" /* critical conditions */
53 #define SD_ERR "<3>" /* error conditions */
54 #define SD_WARNING "<4>" /* warning conditions */
55 #define SD_NOTICE "<5>" /* normal but significant condition */
56 #define SD_INFO "<6>" /* informational */
57 #define SD_DEBUG "<7>" /* debug-level messages */
59 /* The first passed file descriptor is fd 3 */
60 #define SD_LISTEN_FDS_START 3
63 Returns how many file descriptors have been passed, or a negative
64 errno code on failure. Optionally, removes the $LISTEN_FDS and
65 $LISTEN_PID file descriptors from the environment (recommended, but
66 problematic in threaded environments). If r is the return value of
67 this function you'll find the file descriptors passed as fds
68 SD_LISTEN_FDS_START to SD_LISTEN_FDS_START+r-1. Returns a negative
69 errno style error code on failure. This function call ensures that
70 the FD_CLOEXEC flag is set for the passed file descriptors, to make
71 sure they are not passed on to child processes. If FD_CLOEXEC shall
72 not be set, the caller needs to unset it after this call for all file
73 descriptors that are used.
75 See sd_listen_fds(3) for more information.
77 int sd_listen_fds(int unset_environment);
79 int sd_listen_fds_with_names(int unset_environment, char ***names);
82 Helper call for identifying a passed file descriptor. Returns 1 if
83 the file descriptor is a FIFO in the file system stored under the
84 specified path, 0 otherwise. If path is NULL a path name check will
85 not be done and the call only verifies if the file descriptor
86 refers to a FIFO. Returns a negative errno style error code on
89 See sd_is_fifo(3) for more information.
91 int sd_is_fifo(int fd, const char *path);
94 Helper call for identifying a passed file descriptor. Returns 1 if
95 the file descriptor is a special character device on the file
96 system stored under the specified path, 0 otherwise.
97 If path is NULL a path name check will not be done and the call
98 only verifies if the file descriptor refers to a special character.
99 Returns a negative errno style error code on failure.
101 See sd_is_special(3) for more information.
103 int sd_is_special(int fd, const char *path);
106 Helper call for identifying a passed file descriptor. Returns 1 if
107 the file descriptor is a socket of the specified family (AF_INET,
108 ...) and type (SOCK_DGRAM, SOCK_STREAM, ...), 0 otherwise. If
109 family is 0 a socket family check will not be done. If type is 0 a
110 socket type check will not be done and the call only verifies if
111 the file descriptor refers to a socket. If listening is > 0 it is
112 verified that the socket is in listening mode. (i.e. listen() has
113 been called) If listening is == 0 it is verified that the socket is
114 not in listening mode. If listening is < 0 no listening mode check
115 is done. Returns a negative errno style error code on failure.
117 See sd_is_socket(3) for more information.
119 int sd_is_socket(int fd, int family, int type, int listening);
122 Helper call for identifying a passed file descriptor. Returns 1 if
123 the file descriptor is an Internet socket, of the specified family
124 (either AF_INET or AF_INET6) and the specified type (SOCK_DGRAM,
125 SOCK_STREAM, ...), 0 otherwise. If version is 0 a protocol version
126 check is not done. If type is 0 a socket type check will not be
127 done. If port is 0 a socket port check will not be done. The
128 listening flag is used the same way as in sd_is_socket(). Returns a
129 negative errno style error code on failure.
131 See sd_is_socket_inet(3) for more information.
133 int sd_is_socket_inet(int fd, int family, int type, int listening, uint16_t port);
136 Helper call for identifying a passed file descriptor. Returns 1 if the
137 file descriptor is an Internet socket of the specified type
138 (SOCK_DGRAM, SOCK_STREAM, ...), and if the address of the socket is
139 the same as the address specified by addr. The listening flag is used
140 the same way as in sd_is_socket(). Returns a negative errno style
141 error code on failure.
143 See sd_is_socket_sockaddr(3) for more information.
145 int sd_is_socket_sockaddr(int fd, int type, const struct sockaddr* addr, unsigned addr_len, int listening);
148 Helper call for identifying a passed file descriptor. Returns 1 if
149 the file descriptor is an AF_UNIX socket of the specified type
150 (SOCK_DGRAM, SOCK_STREAM, ...) and path, 0 otherwise. If type is 0
151 a socket type check will not be done. If path is NULL a socket path
152 check will not be done. For normal AF_UNIX sockets set length to
153 0. For abstract namespace sockets set length to the length of the
154 socket name (including the initial 0 byte), and pass the full
155 socket path in path (including the initial 0 byte). The listening
156 flag is used the same way as in sd_is_socket(). Returns a negative
157 errno style error code on failure.
159 See sd_is_socket_unix(3) for more information.
161 int sd_is_socket_unix(int fd, int type, int listening, const char *path, size_t length);
163 #if 0 /** UNNEEDED by elogind **/
165 Helper call for identifying a passed file descriptor. Returns 1 if
166 the file descriptor is a POSIX Message Queue of the specified name,
167 0 otherwise. If path is NULL a message queue name check is not
168 done. Returns a negative errno style error code on failure.
170 See sd_is_mq(3) for more information.
172 int sd_is_mq(int fd, const char *path);
176 Informs systemd about changed daemon state. This takes a number of
177 newline separated environment-style variable assignments in a
178 string. The following variables are known:
180 MAINPID=... The main PID of a daemon, in case elogind did not
181 fork off the process itself. Example: "MAINPID=4711"
183 READY=1 Tells elogind that daemon startup or daemon reload
184 is finished (only relevant for services of Type=notify).
185 The passed argument is a boolean "1" or "0". Since there
186 is little value in signaling non-readiness the only
187 value daemons should send is "READY=1".
189 RELOADING=1 Tell elogind that the daemon began reloading its
190 configuration. When the configuration has been
191 reloaded completely, READY=1 should be sent to inform
194 STOPPING=1 Tells elogind that the daemon is about to go down.
196 STATUS=... Passes a single-line status string back to systemd
197 that describes the daemon state. This is free-form
198 and can be used for various purposes: general state
199 feedback, fsck-like programs could pass completion
200 percentages and failing programs could pass a human
201 readable error message. Example: "STATUS=Completed
202 66% of file system check..."
204 ERRNO=... If a daemon fails, the errno-style error code,
205 formatted as string. Example: "ERRNO=2" for ENOENT.
207 BUSERROR=... If a daemon fails, the D-Bus error-style error
208 code. Example: "BUSERROR=org.freedesktop.DBus.Error.TimedOut"
210 WATCHDOG=1 Tells systemd to update the watchdog timestamp.
211 Services using this feature should do this in
212 regular intervals. A watchdog framework can use the
213 timestamps to detect failed services. Also see
214 sd_watchdog_enabled() below.
217 Reset watchdog_usec value during runtime.
218 To reset watchdog_usec value, start the service again.
219 Example: "WATCHDOG_USEC=20000000"
221 FDSTORE=1 Store the file descriptors passed along with the
222 message in the per-service file descriptor store,
223 and pass them to the main process again on next
224 invocation. This variable is only supported with
225 sd_pid_notify_with_fds().
228 Remove one or more file descriptors from the file
229 descriptor store, identified by the name specified
230 in FDNAME=, see below.
232 FDNAME= A name to assign to new file descriptors stored in the
233 file descriptor store, or the name of the file descriptors
234 to remove in case of FDSTOREREMOVE=1.
236 Daemons can choose to send additional variables. However, it is
237 recommended to prefix variable names not listed above with X_.
239 Returns a negative errno-style error code on failure. Returns > 0
240 if systemd could be notified, 0 if it couldn't possibly because
241 systemd is not running.
243 Example: When a daemon finished starting up, it could issue this
244 call to notify systemd about it:
246 sd_notify(0, "READY=1");
248 See sd_notifyf() for more complete examples.
250 See sd_notify(3) for more information.
252 int sd_notify(int unset_environment, const char *state);
255 Similar to sd_notify() but takes a format string.
257 Example 1: A daemon could send the following after initialization:
259 sd_notifyf(0, "READY=1\n"
260 "STATUS=Processing requests...\n"
262 (unsigned long) getpid());
264 Example 2: A daemon could send the following shortly before
267 sd_notifyf(0, "STATUS=Failed to start up: %s\n"
272 See sd_notifyf(3) for more information.
274 int sd_notifyf(int unset_environment, const char *format, ...) _sd_printf_(2,3);
277 Similar to sd_notify(), but send the message on behalf of another
278 process, if the appropriate permissions are available.
280 int sd_pid_notify(pid_t pid, int unset_environment, const char *state);
283 Similar to sd_notifyf(), but send the message on behalf of another
284 process, if the appropriate permissions are available.
286 int sd_pid_notifyf(pid_t pid, int unset_environment, const char *format, ...) _sd_printf_(3,4);
289 Similar to sd_pid_notify(), but also passes the specified fd array
290 to the service manager for storage. This is particularly useful for
293 int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char *state, const int *fds, unsigned n_fds);
296 Returns > 0 if the system was booted with systemd. Returns < 0 on
297 error. Returns 0 if the system was not booted with systemd. Note
298 that all of the functions above handle non-systemd boots just
299 fine. You should NOT protect them with a call to this function. Also
300 note that this function checks whether the system, not the user
301 session is controlled by systemd. However the functions above work
302 for both user and system services.
304 See sd_booted(3) for more information.
309 Returns > 0 if the service manager expects watchdog keep-alive
310 events to be sent regularly via sd_notify(0, "WATCHDOG=1"). Returns
311 0 if it does not expect this. If the usec argument is non-NULL
312 returns the watchdog timeout in µs after which the service manager
313 will act on a process that has not sent a watchdog keep alive
314 message. This function is useful to implement services that
315 recognize automatically if they are being run under supervision of
316 systemd with WatchdogSec= set. It is recommended for clients to
317 generate keep-alive pings via sd_notify(0, "WATCHDOG=1") every half
318 of the returned time.
320 See sd_watchdog_enabled(3) for more information.
322 int sd_watchdog_enabled(int unset_environment, uint64_t *usec);
324 _SD_END_DECLARATIONS;