1 #ifndef foosddaemonhfoo
2 #define foosddaemonhfoo
5 This file is part of systemd.
7 Copyright 2013 Lennart Poettering
9 systemd is free software; you can redistribute it and/or modify it
10 under the terms of the GNU Lesser General Public License as published by
11 the Free Software Foundation; either version 2.1 of the License, or
12 (at your option) any later version.
14 systemd is distributed in the hope that it will be useful, but
15 WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 Lesser General Public License for more details.
19 You should have received a copy of the GNU Lesser General Public License
20 along with systemd; If not, see <http://www.gnu.org/licenses/>.
24 #include <sys/types.h>
26 #include "_sd-common.h"
28 _SD_BEGIN_DECLARATIONS;
31 The following functionality is provided:
33 - Support for logging with log levels on stderr
34 - File descriptor passing for socket-based activation
35 - Daemon startup and status notification
36 - Detection of systemd boots
38 See sd-daemon(3) for more information.
42 Log levels for usage on stderr:
44 fprintf(stderr, SD_NOTICE "Hello World!\n");
46 This is similar to printk() usage in the kernel.
48 #define SD_EMERG "<0>" /* system is unusable */
49 #define SD_ALERT "<1>" /* action must be taken immediately */
50 #define SD_CRIT "<2>" /* critical conditions */
51 #define SD_ERR "<3>" /* error conditions */
52 #define SD_WARNING "<4>" /* warning conditions */
53 #define SD_NOTICE "<5>" /* normal but significant condition */
54 #define SD_INFO "<6>" /* informational */
55 #define SD_DEBUG "<7>" /* debug-level messages */
57 /* The first passed file descriptor is fd 3 */
58 #define SD_LISTEN_FDS_START 3
60 #if 0 /// UNNEEDED by elogind
62 Returns how many file descriptors have been passed, or a negative
63 errno code on failure. Optionally, removes the $LISTEN_FDS and
64 $LISTEN_PID file descriptors from the environment (recommended, but
65 problematic in threaded environments). If r is the return value of
66 this function you'll find the file descriptors passed as fds
67 SD_LISTEN_FDS_START to SD_LISTEN_FDS_START+r-1. Returns a negative
68 errno style error code on failure. This function call ensures that
69 the FD_CLOEXEC flag is set for the passed file descriptors, to make
70 sure they are not passed on to child processes. If FD_CLOEXEC shall
71 not be set, the caller needs to unset it after this call for all file
72 descriptors that are used.
74 See sd_listen_fds(3) for more information.
76 int sd_listen_fds(int unset_environment);
78 int sd_listen_fds_with_names(int unset_environment, char ***names);
81 Helper call for identifying a passed file descriptor. Returns 1 if
82 the file descriptor is a FIFO in the file system stored under the
83 specified path, 0 otherwise. If path is NULL a path name check will
84 not be done and the call only verifies if the file descriptor
85 refers to a FIFO. Returns a negative errno style error code on
88 See sd_is_fifo(3) for more information.
90 int sd_is_fifo(int fd, const char *path);
93 Helper call for identifying a passed file descriptor. Returns 1 if
94 the file descriptor is a special character device on the file
95 system stored under the specified path, 0 otherwise.
96 If path is NULL a path name check will not be done and the call
97 only verifies if the file descriptor refers to a special character.
98 Returns a negative errno style error code on failure.
100 See sd_is_special(3) for more information.
102 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);
121 #if 0 /// UNNEEDED by elogind
123 Helper call for identifying a passed file descriptor. Returns 1 if
124 the file descriptor is an Internet socket, of the specified family
125 (either AF_INET or AF_INET6) and the specified type (SOCK_DGRAM,
126 SOCK_STREAM, ...), 0 otherwise. If version is 0 a protocol version
127 check is not done. If type is 0 a socket type check will not be
128 done. If port is 0 a socket port check will not be done. The
129 listening flag is used the same way as in sd_is_socket(). Returns a
130 negative errno style error code on failure.
132 See sd_is_socket_inet(3) for more information.
134 int sd_is_socket_inet(int fd, int family, int type, int listening, uint16_t port);
137 Helper call for identifying a passed file descriptor. Returns 1 if
138 the file descriptor is an AF_UNIX socket of the specified type
139 (SOCK_DGRAM, SOCK_STREAM, ...) and path, 0 otherwise. If type is 0
140 a socket type check will not be done. If path is NULL a socket path
141 check will not be done. For normal AF_UNIX sockets set length to
142 0. For abstract namespace sockets set length to the length of the
143 socket name (including the initial 0 byte), and pass the full
144 socket path in path (including the initial 0 byte). The listening
145 flag is used the same way as in sd_is_socket(). Returns a negative
146 errno style error code on failure.
148 See sd_is_socket_unix(3) for more information.
150 int sd_is_socket_unix(int fd, int type, int listening, const char *path, size_t length);
153 Helper call for identifying a passed file descriptor. Returns 1 if
154 the file descriptor is a POSIX Message Queue of the specified name,
155 0 otherwise. If path is NULL a message queue name check is not
156 done. Returns a negative errno style error code on failure.
158 See sd_is_mq(3) for more information.
160 int sd_is_mq(int fd, const char *path);
164 Informs systemd about changed daemon state. This takes a number of
165 newline separated environment-style variable assignments in a
166 string. The following variables are known:
168 READY=1 Tells systemd that daemon startup is finished (only
169 relevant for services of Type=notify). The passed
170 argument is a boolean "1" or "0". Since there is
171 little value in signaling non-readiness the only
172 value daemons should send is "READY=1".
174 STATUS=... Passes a single-line status string back to systemd
175 that describes the daemon state. This is free-form
176 and can be used for various purposes: general state
177 feedback, fsck-like programs could pass completion
178 percentages and failing programs could pass a human
179 readable error message. Example: "STATUS=Completed
180 66% of file system check..."
182 ERRNO=... If a daemon fails, the errno-style error code,
183 formatted as string. Example: "ERRNO=2" for ENOENT.
185 BUSERROR=... If a daemon fails, the D-Bus error-style error
186 code. Example: "BUSERROR=org.freedesktop.DBus.Error.TimedOut"
188 MAINPID=... The main pid of a daemon, in case systemd did not
189 fork off the process itself. Example: "MAINPID=4711"
191 WATCHDOG=1 Tells systemd to update the watchdog timestamp.
192 Services using this feature should do this in
193 regular intervals. A watchdog framework can use the
194 timestamps to detect failed services. Also see
195 sd_watchdog_enabled() below.
197 FDSTORE=1 Store the file descriptors passed along with the
198 message in the per-service file descriptor store,
199 and pass them to the main process again on next
200 invocation. This variable is only supported with
201 sd_pid_notify_with_fds().
203 Daemons can choose to send additional variables. However, it is
204 recommended to prefix variable names not listed above with X_.
206 Returns a negative errno-style error code on failure. Returns > 0
207 if systemd could be notified, 0 if it couldn't possibly because
208 systemd is not running.
210 Example: When a daemon finished starting up, it could issue this
211 call to notify systemd about it:
213 sd_notify(0, "READY=1");
215 See sd_notifyf() for more complete examples.
217 See sd_notify(3) for more information.
219 int sd_notify(int unset_environment, const char *state);
221 #if 0 /// UNNEEDED by elogind
223 Similar to sd_notify() but takes a format string.
225 Example 1: A daemon could send the following after initialization:
227 sd_notifyf(0, "READY=1\n"
228 "STATUS=Processing requests...\n"
230 (unsigned long) getpid());
232 Example 2: A daemon could send the following shortly before
235 sd_notifyf(0, "STATUS=Failed to start up: %s\n"
240 See sd_notifyf(3) for more information.
242 int sd_notifyf(int unset_environment, const char *format, ...) _sd_printf_(2,3);
245 Similar to sd_notify(), but send the message on behalf of another
246 process, if the appropriate permissions are available.
248 int sd_pid_notify(pid_t pid, int unset_environment, const char *state);
251 Similar to sd_notifyf(), but send the message on behalf of another
252 process, if the appropriate permissions are available.
254 int sd_pid_notifyf(pid_t pid, int unset_environment, const char *format, ...) _sd_printf_(3,4);
258 Similar to sd_pid_notify(), but also passes the specified fd array
259 to the service manager for storage. This is particularly useful for
262 int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char *state, const int *fds, unsigned n_fds);
264 #if 0 /// UNNEEDED by elogind
266 Returns > 0 if the system was booted with systemd. Returns < 0 on
267 error. Returns 0 if the system was not booted with systemd. Note
268 that all of the functions above handle non-systemd boots just
269 fine. You should NOT protect them with a call to this function. Also
270 note that this function checks whether the system, not the user
271 session is controlled by systemd. However the functions above work
272 for both user and system services.
274 See sd_booted(3) for more information.
280 Returns > 0 if the service manager expects watchdog keep-alive
281 events to be sent regularly via sd_notify(0, "WATCHDOG=1"). Returns
282 0 if it does not expect this. If the usec argument is non-NULL
283 returns the watchdog timeout in µs after which the service manager
284 will act on a process that has not sent a watchdog keep alive
285 message. This function is useful to implement services that
286 recognize automatically if they are being run under supervision of
287 systemd with WatchdogSec= set. It is recommended for clients to
288 generate keep-alive pings via sd_notify(0, "WATCHDOG=1") every half
289 of the returned time.
291 See sd_watchdog_enabled(3) for more information.
293 int sd_watchdog_enabled(int unset_environment, uint64_t *usec);
295 _SD_END_DECLARATIONS;