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
61 Returns how many file descriptors have been passed, or a negative
62 errno code on failure. Optionally, removes the $LISTEN_FDS and
63 $LISTEN_PID file descriptors from the environment (recommended, but
64 problematic in threaded environments). If r is the return value of
65 this function you'll find the file descriptors passed as fds
66 SD_LISTEN_FDS_START to SD_LISTEN_FDS_START+r-1. Returns a negative
67 errno style error code on failure. This function call ensures that
68 the FD_CLOEXEC flag is set for the passed file descriptors, to make
69 sure they are not passed on to child processes. If FD_CLOEXEC shall
70 not be set, the caller needs to unset it after this call for all file
71 descriptors that are used.
73 See sd_listen_fds(3) for more information.
75 int sd_listen_fds(int unset_environment);
77 int sd_listen_fds_with_names(int unset_environment, char ***names);
79 #if 0 /// UNNEEDED by elogind
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 the
138 file descriptor is an Internet socket of the specified type
139 (SOCK_DGRAM, SOCK_STREAM, ...), and if the address of the socket is
140 the same as the address specified by addr. The listening flag is used
141 the same way as in sd_is_socket(). Returns a negative errno style
142 error code on failure.
144 See sd_is_socket_sockaddr(3) for more information.
146 int sd_is_socket_sockaddr(int fd, int type, const struct sockaddr* addr, unsigned addr_len, int listening);
149 Helper call for identifying a passed file descriptor. Returns 1 if
150 the file descriptor is an AF_UNIX socket of the specified type
151 (SOCK_DGRAM, SOCK_STREAM, ...) and path, 0 otherwise. If type is 0
152 a socket type check will not be done. If path is NULL a socket path
153 check will not be done. For normal AF_UNIX sockets set length to
154 0. For abstract namespace sockets set length to the length of the
155 socket name (including the initial 0 byte), and pass the full
156 socket path in path (including the initial 0 byte). The listening
157 flag is used the same way as in sd_is_socket(). Returns a negative
158 errno style error code on failure.
160 See sd_is_socket_unix(3) for more information.
162 int sd_is_socket_unix(int fd, int type, int listening, const char *path, size_t length);
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 READY=1 Tells systemd that daemon startup is finished (only
181 relevant for services of Type=notify). The passed
182 argument is a boolean "1" or "0". Since there is
183 little value in signaling non-readiness the only
184 value daemons should send is "READY=1".
186 STATUS=... Passes a single-line status string back to systemd
187 that describes the daemon state. This is free-form
188 and can be used for various purposes: general state
189 feedback, fsck-like programs could pass completion
190 percentages and failing programs could pass a human
191 readable error message. Example: "STATUS=Completed
192 66% of file system check..."
194 ERRNO=... If a daemon fails, the errno-style error code,
195 formatted as string. Example: "ERRNO=2" for ENOENT.
197 BUSERROR=... If a daemon fails, the D-Bus error-style error
198 code. Example: "BUSERROR=org.freedesktop.DBus.Error.TimedOut"
200 MAINPID=... The main pid of a daemon, in case systemd did not
201 fork off the process itself. Example: "MAINPID=4711"
203 WATCHDOG=1 Tells systemd to update the watchdog timestamp.
204 Services using this feature should do this in
205 regular intervals. A watchdog framework can use the
206 timestamps to detect failed services. Also see
207 sd_watchdog_enabled() below.
209 FDSTORE=1 Store the file descriptors passed along with the
210 message in the per-service file descriptor store,
211 and pass them to the main process again on next
212 invocation. This variable is only supported with
213 sd_pid_notify_with_fds().
216 Reset watchdog_usec value during runtime.
217 To reset watchdog_usec value, start the service again.
218 Example: "WATCHDOG_USEC=20000000"
220 Daemons can choose to send additional variables. However, it is
221 recommended to prefix variable names not listed above with X_.
223 Returns a negative errno-style error code on failure. Returns > 0
224 if systemd could be notified, 0 if it couldn't possibly because
225 systemd is not running.
227 Example: When a daemon finished starting up, it could issue this
228 call to notify systemd about it:
230 sd_notify(0, "READY=1");
232 See sd_notifyf() for more complete examples.
234 See sd_notify(3) for more information.
236 int sd_notify(int unset_environment, const char *state);
238 #if 0 /// UNNEEDED by elogind
240 Similar to sd_notify() but takes a format string.
242 Example 1: A daemon could send the following after initialization:
244 sd_notifyf(0, "READY=1\n"
245 "STATUS=Processing requests...\n"
247 (unsigned long) getpid());
249 Example 2: A daemon could send the following shortly before
252 sd_notifyf(0, "STATUS=Failed to start up: %s\n"
257 See sd_notifyf(3) for more information.
259 int sd_notifyf(int unset_environment, const char *format, ...) _sd_printf_(2,3);
262 Similar to sd_notify(), but send the message on behalf of another
263 process, if the appropriate permissions are available.
265 int sd_pid_notify(pid_t pid, int unset_environment, const char *state);
268 Similar to sd_notifyf(), but send the message on behalf of another
269 process, if the appropriate permissions are available.
271 int sd_pid_notifyf(pid_t pid, int unset_environment, const char *format, ...) _sd_printf_(3,4);
275 Similar to sd_pid_notify(), but also passes the specified fd array
276 to the service manager for storage. This is particularly useful for
279 int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char *state, const int *fds, unsigned n_fds);
282 Returns > 0 if the system was booted with systemd. Returns < 0 on
283 error. Returns 0 if the system was not booted with systemd. Note
284 that all of the functions above handle non-systemd boots just
285 fine. You should NOT protect them with a call to this function. Also
286 note that this function checks whether the system, not the user
287 session is controlled by systemd. However the functions above work
288 for both user and system services.
290 See sd_booted(3) for more information.
295 Returns > 0 if the service manager expects watchdog keep-alive
296 events to be sent regularly via sd_notify(0, "WATCHDOG=1"). Returns
297 0 if it does not expect this. If the usec argument is non-NULL
298 returns the watchdog timeout in µs after which the service manager
299 will act on a process that has not sent a watchdog keep alive
300 message. This function is useful to implement services that
301 recognize automatically if they are being run under supervision of
302 systemd with WatchdogSec= set. It is recommended for clients to
303 generate keep-alive pings via sd_notify(0, "WATCHDOG=1") every half
304 of the returned time.
306 See sd_watchdog_enabled(3) for more information.
308 int sd_watchdog_enabled(int unset_environment, uint64_t *usec);
310 _SD_END_DECLARATIONS;