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 258
