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/plain/src/sd-daemon.h
62 http://cgit.freedesktop.org/systemd/plain/src/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(7) 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 #if (__GNUC__ >= 4) && !defined(SD_EXPORT_SYMBOLS)
80 #define _sd_hidden_ __attribute__ ((visibility("hidden")))
87 Log levels for usage on stderr:
89 fprintf(stderr, SD_NOTICE "Hello World!\n");
91 This is similar to printk() usage in the kernel.
93 #define SD_EMERG "<0>" /* system is unusable */
94 #define SD_ALERT "<1>" /* action must be taken immediately */
95 #define SD_CRIT "<2>" /* critical conditions */
96 #define SD_ERR "<3>" /* error conditions */
97 #define SD_WARNING "<4>" /* warning conditions */
98 #define SD_NOTICE "<5>" /* normal but significant condition */
99 #define SD_INFO "<6>" /* informational */
100 #define SD_DEBUG "<7>" /* debug-level messages */
102 /* The first passed file descriptor is fd 3 */
103 #define SD_LISTEN_FDS_START 3
106 Returns how many file descriptors have been passed, or a negative
107 errno code on failure. Optionally, removes the $LISTEN_FDS and
108 $LISTEN_PID file descriptors from the environment (recommended, but
109 problematic in threaded environments). If r is the return value of
110 this function you'll find the file descriptors passed as fds
111 SD_LISTEN_FDS_START to SD_LISTEN_FDS_START+r-1. Returns a negative
112 errno style error code on failure. This function call ensures that
113 the FD_CLOEXEC flag is set for the passed file descriptors, to make
114 sure they are not passed on to child processes. If FD_CLOEXEC shall
115 not be set, the caller needs to unset it after this call for all file
116 descriptors that are used.
118 See sd_listen_fds(3) for more information.
120 int sd_listen_fds(int unset_environment) _sd_hidden_;
123 Helper call for identifying a passed file descriptor. Returns 1 if
124 the file descriptor is a FIFO in the file system stored under the
125 specified path, 0 otherwise. If path is NULL a path name check will
126 not be done and the call only verifies if the file descriptor
127 refers to a FIFO. Returns a negative errno style error code on
130 See sd_is_fifo(3) for more information.
132 int sd_is_fifo(int fd, const char *path) _sd_hidden_;
135 Helper call for identifying a passed file descriptor. Returns 1 if
136 the file descriptor is a socket of the specified family (AF_INET,
137 ...) and type (SOCK_DGRAM, SOCK_STREAM, ...), 0 otherwise. If
138 family is 0 a socket family check will not be done. If type is 0 a
139 socket type check will not be done and the call only verifies if
140 the file descriptor refers to a socket. If listening is > 0 it is
141 verified that the socket is in listening mode. (i.e. listen() has
142 been called) If listening is == 0 it is verified that the socket is
143 not in listening mode. If listening is < 0 no listening mode check
144 is done. Returns a negative errno style error code on failure.
146 See sd_is_socket(3) for more information.
148 int sd_is_socket(int fd, int family, int type, int listening) _sd_hidden_;
151 Helper call for identifying a passed file descriptor. Returns 1 if
152 the file descriptor is an Internet socket, of the specified family
153 (either AF_INET or AF_INET6) and the specified type (SOCK_DGRAM,
154 SOCK_STREAM, ...), 0 otherwise. If version is 0 a protocol version
155 check is not done. If type is 0 a socket type check will not be
156 done. If port is 0 a socket port check will not be done. The
157 listening flag is used the same way as in sd_is_socket(). Returns a
158 negative errno style error code on failure.
160 See sd_is_socket_inet(3) for more information.
162 int sd_is_socket_inet(int fd, int family, int type, int listening, uint16_t port) _sd_hidden_;
165 Helper call for identifying a passed file descriptor. Returns 1 if
166 the file descriptor is an AF_UNIX socket of the specified type
167 (SOCK_DGRAM, SOCK_STREAM, ...) and path, 0 otherwise. If type is 0
168 a socket type check will not be done. If path is NULL a socket path
169 check will not be done. For normal AF_UNIX sockets set length to
170 0. For abstract namespace sockets set length to the length of the
171 socket name (including the initial 0 byte), and pass the full
172 socket path in path (including the initial 0 byte). The listening
173 flag is used the same way as in sd_is_socket(). Returns a negative
174 errno style error code on failure.
176 See sd_is_socket_unix(3) for more information.
178 int sd_is_socket_unix(int fd, int type, int listening, const char *path, size_t length) _sd_hidden_;
181 Informs systemd about changed daemon state. This takes a number of
182 newline separated environment-style variable assignments in a
183 string. The following variables are known:
185 READY=1 Tells systemd that daemon startup is finished (only
186 relevant for services of Type=notify). The passed
187 argument is a boolean "1" or "0". Since there is
188 little value in signaling non-readiness the only
189 value daemons should send is "READY=1".
191 STATUS=... Passes a single-line status string back to systemd
192 that describes the daemon state. This is free-from
193 and can be used for various purposes: general state
194 feedback, fsck-like programs could pass completion
195 percentages and failing programs could pass a human
196 readable error message. Example: "STATUS=Completed
197 66% of file system check..."
199 ERRNO=... If a daemon fails, the errno-style error code,
200 formatted as string. Example: "ERRNO=2" for ENOENT.
202 BUSERROR=... If a daemon fails, the D-Bus error-style error
203 code. Example: "BUSERROR=org.freedesktop.DBus.Error.TimedOut"
205 MAINPID=... The main pid of a daemon, in case systemd did not
206 fork off the process itself. Example: "MAINPID=4711"
208 Daemons can choose to send additional variables. However, it is
209 recommended to prefix variable names not listed above with X_.
211 Returns a negative errno-style error code on failure. Returns > 0
212 if systemd could be notified, 0 if it couldn't possibly because
213 systemd is not running.
215 Example: When a daemon finished starting up, it could issue this
216 call to notify systemd about it:
218 sd_notify(0, "READY=1");
220 See sd_notifyf() for more complete examples.
222 See sd_notify(3) for more information.
224 int sd_notify(int unset_environment, const char *state) _sd_hidden_;
227 Similar to sd_notify() but takes a format string.
229 Example 1: A daemon could send the following after initialization:
231 sd_notifyf(0, "READY=1\n"
232 "STATUS=Processing requests...\n"
234 (unsigned long) getpid());
236 Example 2: A daemon could send the following shortly before
239 sd_notifyf(0, "STATUS=Failed to start up: %s\n"
244 See sd_notifyf(3) for more information.
246 int sd_notifyf(int unset_environment, const char *format, ...) _sd_printf_attr_(2,3) _sd_hidden_;
249 Returns > 0 if the system was booted with systemd. Returns < 0 on
250 error. Returns 0 if the system was not booted with systemd. Note
251 that all of the functions above handle non-systemd boots just
252 fine. You should NOT protect them with a call to this function. Also
253 note that this function checks whether the system, not the user
254 session is controlled by systemd. However the functions above work
255 for both user and system services.
257 See sd_booted(3) for more information.
259 int sd_booted(void) _sd_hidden_;