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>
25 #include <sys/socket.h>
27 #include "_sd-common.h"
29 _SD_BEGIN_DECLARATIONS;
32 The following functionality is provided:
34 - Support for logging with log levels on stderr
35 - File descriptor passing for socket-based activation
36 - Daemon startup and status notification
37 - Detection of systemd boots
39 See sd-daemon(3) for more information.
43 Log levels for usage on stderr:
45 fprintf(stderr, SD_NOTICE "Hello World!\n");
47 This is similar to printk() usage in the kernel.
49 #define SD_EMERG "<0>" /* system is unusable */
50 #define SD_ALERT "<1>" /* action must be taken immediately */
51 #define SD_CRIT "<2>" /* critical conditions */
52 #define SD_ERR "<3>" /* error conditions */
53 #define SD_WARNING "<4>" /* warning conditions */
54 #define SD_NOTICE "<5>" /* normal but significant condition */
55 #define SD_INFO "<6>" /* informational */
56 #define SD_DEBUG "<7>" /* debug-level messages */
58 /* The first passed file descriptor is fd 3 */
59 #define SD_LISTEN_FDS_START 3
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);
80 #if 0 /// UNNEEDED by elogind
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);
107 Helper call for identifying a passed file descriptor. Returns 1 if
108 the file descriptor is a socket of the specified family (AF_INET,
109 ...) and type (SOCK_DGRAM, SOCK_STREAM, ...), 0 otherwise. If
110 family is 0 a socket family check will not be done. If type is 0 a
111 socket type check will not be done and the call only verifies if
112 the file descriptor refers to a socket. If listening is > 0 it is
113 verified that the socket is in listening mode. (i.e. listen() has
114 been called) If listening is == 0 it is verified that the socket is
115 not in listening mode. If listening is < 0 no listening mode check
116 is done. Returns a negative errno style error code on failure.
118 See sd_is_socket(3) for more information.
120 int sd_is_socket(int fd, int family, int type, int listening);
122 #if 0 /// UNNEEDED by elogind
124 Helper call for identifying a passed file descriptor. Returns 1 if
125 the file descriptor is an Internet socket, of the specified family
126 (either AF_INET or AF_INET6) and the specified type (SOCK_DGRAM,
127 SOCK_STREAM, ...), 0 otherwise. If version is 0 a protocol version
128 check is not done. If type is 0 a socket type check will not be
129 done. If port is 0 a socket port check will not be done. The
130 listening flag is used the same way as in sd_is_socket(). Returns a
131 negative errno style error code on failure.
133 See sd_is_socket_inet(3) for more information.
135 int sd_is_socket_inet(int fd, int family, int type, int listening, uint16_t port);
138 Helper call for identifying a passed file descriptor. Returns 1 if the
139 file descriptor is an Internet socket of the specified type
140 (SOCK_DGRAM, SOCK_STREAM, ...), and if the address of the socket is
141 the same as the address specified by addr. The listening flag is used
142 the same way as in sd_is_socket(). Returns a negative errno style
143 error code on failure.
145 See sd_is_socket_sockaddr(3) for more information.
147 int sd_is_socket_sockaddr(int fd, int type, const struct sockaddr* addr, unsigned addr_len, int listening);
150 Helper call for identifying a passed file descriptor. Returns 1 if
151 the file descriptor is an AF_UNIX socket of the specified type
152 (SOCK_DGRAM, SOCK_STREAM, ...) and path, 0 otherwise. If type is 0
153 a socket type check will not be done. If path is NULL a socket path
154 check will not be done. For normal AF_UNIX sockets set length to
155 0. For abstract namespace sockets set length to the length of the
156 socket name (including the initial 0 byte), and pass the full
157 socket path in path (including the initial 0 byte). The listening
158 flag is used the same way as in sd_is_socket(). Returns a negative
159 errno style error code on failure.
161 See sd_is_socket_unix(3) for more information.
163 int sd_is_socket_unix(int fd, int type, int listening, const char *path, size_t length);
166 Helper call for identifying a passed file descriptor. Returns 1 if
167 the file descriptor is a POSIX Message Queue of the specified name,
168 0 otherwise. If path is NULL a message queue name check is not
169 done. Returns a negative errno style error code on failure.
171 See sd_is_mq(3) for more information.
173 int sd_is_mq(int fd, const char *path);
177 Informs systemd about changed daemon state. This takes a number of
178 newline separated environment-style variable assignments in a
179 string. The following variables are known:
181 READY=1 Tells systemd that daemon startup is finished (only
182 relevant for services of Type=notify). The passed
183 argument is a boolean "1" or "0". Since there is
184 little value in signaling non-readiness the only
185 value daemons should send is "READY=1".
187 STATUS=... Passes a single-line status string back to systemd
188 that describes the daemon state. This is free-form
189 and can be used for various purposes: general state
190 feedback, fsck-like programs could pass completion
191 percentages and failing programs could pass a human
192 readable error message. Example: "STATUS=Completed
193 66% of file system check..."
195 ERRNO=... If a daemon fails, the errno-style error code,
196 formatted as string. Example: "ERRNO=2" for ENOENT.
198 BUSERROR=... If a daemon fails, the D-Bus error-style error
199 code. Example: "BUSERROR=org.freedesktop.DBus.Error.TimedOut"
201 MAINPID=... The main pid of a daemon, in case systemd did not
202 fork off the process itself. Example: "MAINPID=4711"
204 WATCHDOG=1 Tells systemd to update the watchdog timestamp.
205 Services using this feature should do this in
206 regular intervals. A watchdog framework can use the
207 timestamps to detect failed services. Also see
208 sd_watchdog_enabled() below.
210 FDSTORE=1 Store the file descriptors passed along with the
211 message in the per-service file descriptor store,
212 and pass them to the main process again on next
213 invocation. This variable is only supported with
214 sd_pid_notify_with_fds().
217 Reset watchdog_usec value during runtime.
218 To reset watchdog_usec value, start the service again.
219 Example: "WATCHDOG_USEC=20000000"
221 Daemons can choose to send additional variables. However, it is
222 recommended to prefix variable names not listed above with X_.
224 Returns a negative errno-style error code on failure. Returns > 0
225 if systemd could be notified, 0 if it couldn't possibly because
226 systemd is not running.
228 Example: When a daemon finished starting up, it could issue this
229 call to notify systemd about it:
231 sd_notify(0, "READY=1");
233 See sd_notifyf() for more complete examples.
235 See sd_notify(3) for more information.
237 int sd_notify(int unset_environment, const char *state);
239 #if 0 /// UNNEEDED by elogind
241 Similar to sd_notify() but takes a format string.
243 Example 1: A daemon could send the following after initialization:
245 sd_notifyf(0, "READY=1\n"
246 "STATUS=Processing requests...\n"
248 (unsigned long) getpid());
250 Example 2: A daemon could send the following shortly before
253 sd_notifyf(0, "STATUS=Failed to start up: %s\n"
258 See sd_notifyf(3) for more information.
260 int sd_notifyf(int unset_environment, const char *format, ...) _sd_printf_(2,3);
263 Similar to sd_notify(), but send the message on behalf of another
264 process, if the appropriate permissions are available.
266 int sd_pid_notify(pid_t pid, int unset_environment, const char *state);
269 Similar to sd_notifyf(), but send the message on behalf of another
270 process, if the appropriate permissions are available.
272 int sd_pid_notifyf(pid_t pid, int unset_environment, const char *format, ...) _sd_printf_(3,4);
276 Similar to sd_pid_notify(), but also passes the specified fd array
277 to the service manager for storage. This is particularly useful for
280 int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char *state, const int *fds, unsigned n_fds);
283 Returns > 0 if the system was booted with systemd. Returns < 0 on
284 error. Returns 0 if the system was not booted with systemd. Note
285 that all of the functions above handle non-systemd boots just
286 fine. You should NOT protect them with a call to this function. Also
287 note that this function checks whether the system, not the user
288 session is controlled by systemd. However the functions above work
289 for both user and system services.
291 See sd_booted(3) for more information.
296 Returns > 0 if the service manager expects watchdog keep-alive
297 events to be sent regularly via sd_notify(0, "WATCHDOG=1"). Returns
298 0 if it does not expect this. If the usec argument is non-NULL
299 returns the watchdog timeout in µs after which the service manager
300 will act on a process that has not sent a watchdog keep alive
301 message. This function is useful to implement services that
302 recognize automatically if they are being run under supervision of
303 systemd with WatchdogSec= set. It is recommended for clients to
304 generate keep-alive pings via sd_notify(0, "WATCHDOG=1") every half
305 of the returned time.
307 See sd_watchdog_enabled(3) for more information.
309 int sd_watchdog_enabled(int unset_environment, uint64_t *usec);
311 _SD_END_DECLARATIONS;