1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
3 #ifndef foosddaemonhfoo
4 #define foosddaemonhfoo
7 Copyright 2010 Lennart Poettering
9 Permission is hereby granted, free of charge, to any person
10 obtaining a copy of this software and associated documentation files
11 (the "Software"), to deal in the Software without restriction,
12 including without limitation the rights to use, copy, modify, merge,
13 publish, distribute, sublicense, and/or sell copies of the Software,
14 and to permit persons to whom the Software is furnished to do so,
15 subject to the following conditions:
17 The above copyright notice and this permission notice shall be
18 included in all copies or substantial portions of the Software.
20 THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
21 EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
22 MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
23 NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
24 BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
25 ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
26 CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
30 #include <sys/types.h>
38 Reference implementation of a few systemd related interfaces for
39 writing daemons. These interfaces are trivial to implement. To
40 simplify porting we provide this reference implementation.
41 Applications are welcome to reimplement the algorithms described
42 here if they do not want to include these two source files.
44 The following functionality is provided:
46 - Support for logging with log levels on stderr
47 - File descriptor passing for socket-based activation
48 - Daemon startup and status notification
49 - Detection of systemd boots
51 You may compile this with -DDISABLE_SYSTEMD to disable systemd
52 support. This makes all those calls NOPs that are directly related to
53 systemd (i.e. only sd_is_xxx() will stay useful).
55 Since this is drop-in code we don't want any of our symbols to be
56 exported in any case. Hence we declare hidden visibility for all of
59 You may find an up-to-date version of these source files online:
61 http://cgit.freedesktop.org/systemd/systemd/plain/src/systemd/sd-daemon.h
62 http://cgit.freedesktop.org/systemd/systemd/plain/src/libsystemd-daemon/sd-daemon.c
64 This should compile on non-Linux systems, too, but with the
65 exception of the sd_is_xxx() calls all functions will become NOPs.
67 See sd-daemon(3) for more information.
70 #ifndef _sd_printf_attr_
72 # define _sd_printf_attr_(a,b) __attribute__ ((format (printf, a, b)))
74 # define _sd_printf_attr_(a,b)
79 Log levels for usage on stderr:
81 fprintf(stderr, SD_NOTICE "Hello World!\n");
83 This is similar to printk() usage in the kernel.
85 #define SD_EMERG "<0>" /* system is unusable */
86 #define SD_ALERT "<1>" /* action must be taken immediately */
87 #define SD_CRIT "<2>" /* critical conditions */
88 #define SD_ERR "<3>" /* error conditions */
89 #define SD_WARNING "<4>" /* warning conditions */
90 #define SD_NOTICE "<5>" /* normal but significant condition */
91 #define SD_INFO "<6>" /* informational */
92 #define SD_DEBUG "<7>" /* debug-level messages */
94 /* The first passed file descriptor is fd 3 */
95 #define SD_LISTEN_FDS_START 3
98 Returns how many file descriptors have been passed, or a negative
99 errno code on failure. Optionally, removes the $LISTEN_FDS and
100 $LISTEN_PID file descriptors from the environment (recommended, but
101 problematic in threaded environments). If r is the return value of
102 this function you'll find the file descriptors passed as fds
103 SD_LISTEN_FDS_START to SD_LISTEN_FDS_START+r-1. Returns a negative
104 errno style error code on failure. This function call ensures that
105 the FD_CLOEXEC flag is set for the passed file descriptors, to make
106 sure they are not passed on to child processes. If FD_CLOEXEC shall
107 not be set, the caller needs to unset it after this call for all file
108 descriptors that are used.
110 See sd_listen_fds(3) for more information.
112 int sd_listen_fds(int unset_environment);
115 Helper call for identifying a passed file descriptor. Returns 1 if
116 the file descriptor is a FIFO in the file system stored under the
117 specified path, 0 otherwise. If path is NULL a path name check will
118 not be done and the call only verifies if the file descriptor
119 refers to a FIFO. Returns a negative errno style error code on
122 See sd_is_fifo(3) for more information.
124 int sd_is_fifo(int fd, const char *path);
127 Helper call for identifying a passed file descriptor. Returns 1 if
128 the file descriptor is a special character device on the file
129 system stored under the specified path, 0 otherwise.
130 If path is NULL a path name check will not be done and the call
131 only verifies if the file descriptor refers to a special character.
132 Returns a negative errno style error code on failure.
134 See sd_is_special(3) for more information.
136 int sd_is_special(int fd, const char *path);
139 Helper call for identifying a passed file descriptor. Returns 1 if
140 the file descriptor is a socket of the specified family (AF_INET,
141 ...) and type (SOCK_DGRAM, SOCK_STREAM, ...), 0 otherwise. If
142 family is 0 a socket family check will not be done. If type is 0 a
143 socket type check will not be done and the call only verifies if
144 the file descriptor refers to a socket. If listening is > 0 it is
145 verified that the socket is in listening mode. (i.e. listen() has
146 been called) If listening is == 0 it is verified that the socket is
147 not in listening mode. If listening is < 0 no listening mode check
148 is done. Returns a negative errno style error code on failure.
150 See sd_is_socket(3) for more information.
152 int sd_is_socket(int fd, int family, int type, int listening);
155 Helper call for identifying a passed file descriptor. Returns 1 if
156 the file descriptor is an Internet socket, of the specified family
157 (either AF_INET or AF_INET6) and the specified type (SOCK_DGRAM,
158 SOCK_STREAM, ...), 0 otherwise. If version is 0 a protocol version
159 check is not done. If type is 0 a socket type check will not be
160 done. If port is 0 a socket port check will not be done. The
161 listening flag is used the same way as in sd_is_socket(). Returns a
162 negative errno style error code on failure.
164 See sd_is_socket_inet(3) for more information.
166 int sd_is_socket_inet(int fd, int family, int type, int listening, uint16_t port);
169 Helper call for identifying a passed file descriptor. Returns 1 if
170 the file descriptor is an AF_UNIX socket of the specified type
171 (SOCK_DGRAM, SOCK_STREAM, ...) and path, 0 otherwise. If type is 0
172 a socket type check will not be done. If path is NULL a socket path
173 check will not be done. For normal AF_UNIX sockets set length to
174 0. For abstract namespace sockets set length to the length of the
175 socket name (including the initial 0 byte), and pass the full
176 socket path in path (including the initial 0 byte). The listening
177 flag is used the same way as in sd_is_socket(). Returns a negative
178 errno style error code on failure.
180 See sd_is_socket_unix(3) for more information.
182 int sd_is_socket_unix(int fd, int type, int listening, const char *path, size_t length);
185 Helper call for identifying a passed file descriptor. Returns 1 if
186 the file descriptor is a POSIX Message Queue of the specified name,
187 0 otherwise. If path is NULL a message queue name check is not
188 done. Returns a negative errno style error code on failure.
190 See sd_is_mq(3) for more information.
192 int sd_is_mq(int fd, const char *path);
195 Informs systemd about changed daemon state. This takes a number of
196 newline separated environment-style variable assignments in a
197 string. The following variables are known:
199 READY=1 Tells systemd that daemon startup is finished (only
200 relevant for services of Type=notify). The passed
201 argument is a boolean "1" or "0". Since there is
202 little value in signaling non-readiness the only
203 value daemons should send is "READY=1".
205 STATUS=... Passes a single-line status string back to systemd
206 that describes the daemon state. This is free-from
207 and can be used for various purposes: general state
208 feedback, fsck-like programs could pass completion
209 percentages and failing programs could pass a human
210 readable error message. Example: "STATUS=Completed
211 66% of file system check..."
213 ERRNO=... If a daemon fails, the errno-style error code,
214 formatted as string. Example: "ERRNO=2" for ENOENT.
216 BUSERROR=... If a daemon fails, the D-Bus error-style error
217 code. Example: "BUSERROR=org.freedesktop.DBus.Error.TimedOut"
219 MAINPID=... The main pid of a daemon, in case systemd did not
220 fork off the process itself. Example: "MAINPID=4711"
222 WATCHDOG=1 Tells systemd to update the watchdog timestamp.
223 Services using this feature should do this in
224 regular intervals. A watchdog framework can use the
225 timestamps to detect failed services. Also see
226 sd_watchdog_enabled() below.
228 Daemons can choose to send additional variables. However, it is
229 recommended to prefix variable names not listed above with X_.
231 Returns a negative errno-style error code on failure. Returns > 0
232 if systemd could be notified, 0 if it couldn't possibly because
233 systemd is not running.
235 Example: When a daemon finished starting up, it could issue this
236 call to notify systemd about it:
238 sd_notify(0, "READY=1");
240 See sd_notifyf() for more complete examples.
242 See sd_notify(3) for more information.
244 int sd_notify(int unset_environment, const char *state);
247 Similar to sd_notify() but takes a format string.
249 Example 1: A daemon could send the following after initialization:
251 sd_notifyf(0, "READY=1\n"
252 "STATUS=Processing requests...\n"
254 (unsigned long) getpid());
256 Example 2: A daemon could send the following shortly before
259 sd_notifyf(0, "STATUS=Failed to start up: %s\n"
264 See sd_notifyf(3) for more information.
266 int sd_notifyf(int unset_environment, const char *format, ...) _sd_printf_attr_(2,3);
269 Returns > 0 if the system was booted with systemd. Returns < 0 on
270 error. Returns 0 if the system was not booted with systemd. Note
271 that all of the functions above handle non-systemd boots just
272 fine. You should NOT protect them with a call to this function. Also
273 note that this function checks whether the system, not the user
274 session is controlled by systemd. However the functions above work
275 for both user and system services.
277 See sd_booted(3) for more information.
282 Returns > 0 if the service manager expects watchdog keep-alive
283 events to be sent regularly via sd_notify(0, "WATCHDOG=1"). Returns
284 0 if it does not expect this. If the usec argument is non-NULL
285 returns the watchdog timeout in µs after which the service manager
286 will act on a process that has not sent a watchdog keep alive
287 message. This function is useful to implement services that
288 recognize automatically if they are being run under supervision of
289 systemd with WatchdogSec= set. It is recommended for clients to
290 generate keep-alive pings via sd_notify(0, "WATCHDOG=1") every half
291 of the returned time.
293 See sd_watchdog_enabled(3) for more information.
295 int sd_watchdog_enabled(int unset_environment, uint64_t *usec);