D-Bus  1.6.12
sd-daemon.h
1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
2 
3 #ifndef foosddaemonhfoo
4 #define foosddaemonhfoo
5 
6 /***
7  Copyright 2010 Lennart Poettering
8 
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:
16 
17  The above copyright notice and this permission notice shall be
18  included in all copies or substantial portions of the Software.
19 
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
27  SOFTWARE.
28 ***/
29 
30 #include <sys/types.h>
31 #include <inttypes.h>
32 
33 #ifdef __cplusplus
34 extern "C" {
35 #endif
36 
37 /*
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.
43 
44  The following functionality is provided:
45 
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
50 
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).
54 
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
57  them.
58 
59  You may find an up-to-date version of these source files online:
60 
61  http://cgit.freedesktop.org/systemd/plain/src/sd-daemon.h
62  http://cgit.freedesktop.org/systemd/plain/src/sd-daemon.c
63 
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.
66 
67  See sd-daemon(7) for more information.
68 */
69 
70 #if __GNUC__ >= 4
71 #define _sd_printf_attr_(a,b) __attribute__ ((format (printf, a, b)))
72 #define _sd_hidden_ __attribute__ ((visibility("hidden")))
73 #else
74 #define _sd_printf_attr_(a,b)
75 #define _sd_hidden_
76 #endif
77 
78 /*
79  Log levels for usage on stderr:
80 
81  fprintf(stderr, SD_NOTICE "Hello World!\n");
82 
83  This is similar to printk() usage in the kernel.
84 */
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 */
93 
94 /* The first passed file descriptor is fd 3 */
95 #define SD_LISTEN_FDS_START 3
96 
97 /*
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.
109 
110  See sd_listen_fds(3) for more information.
111 */
112 int sd_listen_fds(int unset_environment) _sd_hidden_;
113 
114 /*
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
120  failure.
121 
122  See sd_is_fifo(3) for more information.
123 */
124 int sd_is_fifo(int fd, const char *path) _sd_hidden_;
125 
126 /*
127  Helper call for identifying a passed file descriptor. Returns 1 if
128  the file descriptor is a socket of the specified family (AF_INET,
129  ...) and type (SOCK_DGRAM, SOCK_STREAM, ...), 0 otherwise. If
130  family is 0 a socket family check will not be done. If type is 0 a
131  socket type check will not be done and the call only verifies if
132  the file descriptor refers to a socket. If listening is > 0 it is
133  verified that the socket is in listening mode. (i.e. listen() has
134  been called) If listening is == 0 it is verified that the socket is
135  not in listening mode. If listening is < 0 no listening mode check
136  is done. Returns a negative errno style error code on failure.
137 
138  See sd_is_socket(3) for more information.
139 */
140 int sd_is_socket(int fd, int family, int type, int listening) _sd_hidden_;
141 
142 /*
143  Helper call for identifying a passed file descriptor. Returns 1 if
144  the file descriptor is an Internet socket, of the specified family
145  (either AF_INET or AF_INET6) and the specified type (SOCK_DGRAM,
146  SOCK_STREAM, ...), 0 otherwise. If version is 0 a protocol version
147  check is not done. If type is 0 a socket type check will not be
148  done. If port is 0 a socket port check will not be done. The
149  listening flag is used the same way as in sd_is_socket(). Returns a
150  negative errno style error code on failure.
151 
152  See sd_is_socket_inet(3) for more information.
153 */
154 int sd_is_socket_inet(int fd, int family, int type, int listening, uint16_t port) _sd_hidden_;
155 
156 /*
157  Helper call for identifying a passed file descriptor. Returns 1 if
158  the file descriptor is an AF_UNIX socket of the specified type
159  (SOCK_DGRAM, SOCK_STREAM, ...) and path, 0 otherwise. If type is 0
160  a socket type check will not be done. If path is NULL a socket path
161  check will not be done. For normal AF_UNIX sockets set length to
162  0. For abstract namespace sockets set length to the length of the
163  socket name (including the initial 0 byte), and pass the full
164  socket path in path (including the initial 0 byte). The listening
165  flag is used the same way as in sd_is_socket(). Returns a negative
166  errno style error code on failure.
167 
168  See sd_is_socket_unix(3) for more information.
169 */
170 int sd_is_socket_unix(int fd, int type, int listening, const char *path, size_t length) _sd_hidden_;
171 
172 /*
173  Informs systemd about changed daemon state. This takes a number of
174  newline seperated environment-style variable assignments in a
175  string. The following variables are known:
176 
177  READY=1 Tells systemd that daemon startup is finished (only
178  relevant for services of Type=notify). The passed
179  argument is a boolean "1" or "0". Since there is
180  little value in signalling non-readiness the only
181  value daemons should send is "READY=1".
182 
183  STATUS=... Passes a single-line status string back to systemd
184  that describes the daemon state. This is free-from
185  and can be used for various purposes: general state
186  feedback, fsck-like programs could pass completion
187  percentages and failing programs could pass a human
188  readable error message. Example: "STATUS=Completed
189  66% of file system check..."
190 
191  ERRNO=... If a daemon fails, the errno-style error code,
192  formatted as string. Example: "ERRNO=2" for ENOENT.
193 
194  BUSERROR=... If a daemon fails, the D-Bus error-style error
195  code. Example: "BUSERROR=org.freedesktop.DBus.Error.TimedOut"
196 
197  MAINPID=... The main pid of a daemon, in case systemd did not
198  fork off the process itself. Example: "MAINPID=4711"
199 
200  Daemons can choose to send additional variables. However, it is
201  recommened to prefix variable names not listed above with X_.
202 
203  Returns a negative errno-style error code on failure. Returns > 0
204  if systemd could be notified, 0 if it couldn't possibly because
205  systemd is not running.
206 
207  Example: When a daemon finished starting up, it could issue this
208  call to notify systemd about it:
209 
210  sd_notify(0, "READY=1");
211 
212  See sd_notifyf() for more complete examples.
213 
214  See sd_notify(3) for more information.
215 */
216 int sd_notify(int unset_environment, const char *state) _sd_hidden_;
217 
218 /*
219  Similar to sd_notify() but takes a format string.
220 
221  Example 1: A daemon could send the following after initialization:
222 
223  sd_notifyf(0, "READY=1\n"
224  "STATUS=Processing requests...\n"
225  "MAINPID=%lu",
226  (unsigned long) getpid());
227 
228  Example 2: A daemon could send the following shortly before
229  exiting, on failure:
230 
231  sd_notifyf(0, "STATUS=Failed to start up: %s\n"
232  "ERRNO=%i",
233  strerror(errno),
234  errno);
235 
236  See sd_notifyf(3) for more information.
237 */
238 int sd_notifyf(int unset_environment, const char *format, ...) _sd_printf_attr_(2,3) _sd_hidden_;
239 
240 /*
241  Returns > 0 if the system was booted with systemd. Returns < 0 on
242  error. Returns 0 if the system was not booted with systemd. Note
243  that all of the functions above handle non-systemd boots just
244  fine. You should NOT protect them with a call to this function. Also
245  note that this function checks whether the system, not the user
246  session is controlled by systemd. However the functions above work
247  for both session and system services.
248 
249  See sd_booted(3) for more information.
250 */
251 int sd_booted(void) _sd_hidden_;
252 
253 #ifdef __cplusplus
254 }
255 #endif
256 
257 #endif