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 #else
  73 #define _sd_printf_attr_(a,b)
  74 #endif
  75
  76 #if (__GNUC__ >= 4) && !defined(SD_EXPORT_SYMBOLS)
  77 #define _sd_hidden_ __attribute__ ((visibility("hidden")))
  78 #else
  79 #define _sd_hidden_
  80 #endif
  81
  82 /*
  83   Log levels for usage on stderr:
  84
  85           fprintf(stderr, SD_NOTICE "Hello World!\n");
  86
  87   This is similar to printk() usage in the kernel.
  88 */
  89 #define SD_EMERG   "<0>"  /* system is unusable */
  90 #define SD_ALERT   "<1>"  /* action must be taken immediately */
  91 #define SD_CRIT    "<2>"  /* critical conditions */
  92 #define SD_ERR     "<3>"  /* error conditions */
  93 #define SD_WARNING "<4>"  /* warning conditions */
  94 #define SD_NOTICE  "<5>"  /* normal but significant condition */
  95 #define SD_INFO    "<6>"  /* informational */
  96 #define SD_DEBUG   "<7>"  /* debug-level messages */
  97
  98 /* The first passed file descriptor is fd 3 */
  99 #define SD_LISTEN_FDS_START 3
 100
 101 /*
 102   Returns how many file descriptors have been passed, or a negative
 103   errno code on failure. Optionally, removes the $LISTEN_FDS and
 104   $LISTEN_PID file descriptors from the environment (recommended, but
 105   problematic in threaded environments). If r is the return value of
 106   this function you'll find the file descriptors passed as fds
 107   SD_LISTEN_FDS_START to SD_LISTEN_FDS_START+r-1. Returns a negative
 108   errno style error code on failure. This function call ensures that
 109   the FD_CLOEXEC flag is set for the passed file descriptors, to make
 110   sure they are not passed on to child processes. If FD_CLOEXEC shall
 111   not be set, the caller needs to unset it after this call for all file
 112   descriptors that are used.
 113
 114   See sd_listen_fds(3) for more information.
 115 */
 116 int sd_listen_fds(int unset_environment) _sd_hidden_;
 117
 118 /*
 119   Helper call for identifying a passed file descriptor. Returns 1 if
 120   the file descriptor is a FIFO in the file system stored under the
 121   specified path, 0 otherwise. If path is NULL a path name check will
 122   not be done and the call only verifies if the file descriptor
 123   refers to a FIFO. Returns a negative errno style error code on
 124   failure.
 125
 126   See sd_is_fifo(3) for more information.
 127 */
 128 int sd_is_fifo(int fd, const char *path) _sd_hidden_;
 129
 130 /*
 131   Helper call for identifying a passed file descriptor. Returns 1 if
 132   the file descriptor is a socket of the specified family (AF_INET,
 133   ...) and type (SOCK_DGRAM, SOCK_STREAM, ...), 0 otherwise. If
 134   family is 0 a socket family check will not be done. If type is 0 a
 135   socket type check will not be done and the call only verifies if
 136   the file descriptor refers to a socket. If listening is > 0 it is
 137   verified that the socket is in listening mode. (i.e. listen() has
 138   been called) If listening is == 0 it is verified that the socket is
 139   not in listening mode. If listening is < 0 no listening mode check
 140   is done. Returns a negative errno style error code on failure.
 141
 142   See sd_is_socket(3) for more information.
 143 */
 144 int sd_is_socket(int fd, int family, int type, int listening) _sd_hidden_;
 145
 146 /*
 147   Helper call for identifying a passed file descriptor. Returns 1 if
 148   the file descriptor is an Internet socket, of the specified family
 149   (either AF_INET or AF_INET6) and the specified type (SOCK_DGRAM,
 150   SOCK_STREAM, ...), 0 otherwise. If version is 0 a protocol version
 151   check is not done. If type is 0 a socket type check will not be
 152   done. If port is 0 a socket port check will not be done. The
 153   listening flag is used the same way as in sd_is_socket(). Returns a
 154   negative errno style error code on failure.
 155
 156   See sd_is_socket_inet(3) for more information.
 157 */
 158 int sd_is_socket_inet(int fd, int family, int type, int listening, uint16_t port) _sd_hidden_;
 159
 160 /*
 161   Helper call for identifying a passed file descriptor. Returns 1 if
 162   the file descriptor is an AF_UNIX socket of the specified type
 163   (SOCK_DGRAM, SOCK_STREAM, ...) and path, 0 otherwise. If type is 0
 164   a socket type check will not be done. If path is NULL a socket path
 165   check will not be done. For normal AF_UNIX sockets set length to
 166   0. For abstract namespace sockets set length to the length of the
 167   socket name (including the initial 0 byte), and pass the full
 168   socket path in path (including the initial 0 byte). The listening
 169   flag is used the same way as in sd_is_socket(). Returns a negative
 170   errno style error code on failure.
 171
 172   See sd_is_socket_unix(3) for more information.
 173 */
 174 int sd_is_socket_unix(int fd, int type, int listening, const char *path, size_t length) _sd_hidden_;
 175
 176 /*
 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:
 180
 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 signalling non-readiness the only
 185                   value daemons should send is "READY=1".
 186
 187      STATUS=...   Passes a single-line status string back to systemd
 188                   that describes the daemon state. This is free-from
 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..."
 194
 195      ERRNO=...    If a daemon fails, the errno-style error code,
 196                   formatted as string. Example: "ERRNO=2" for ENOENT.
 197
 198      BUSERROR=... If a daemon fails, the D-Bus error-style error
 199                   code. Example: "BUSERROR=org.freedesktop.DBus.Error.TimedOut"
 200
 201      MAINPID=...  The main pid of a daemon, in case systemd did not
 202                   fork off the process itself. Example: "MAINPID=4711"
 203
 204   Daemons can choose to send additional variables. However, it is
 205   recommened to prefix variable names not listed above with X_.
 206
 207   Returns a negative errno-style error code on failure. Returns > 0
 208   if systemd could be notified, 0 if it couldn't possibly because
 209   systemd is not running.
 210
 211   Example: When a daemon finished starting up, it could issue this
 212   call to notify systemd about it:
 213
 214      sd_notify(0, "READY=1");
 215
 216   See sd_notifyf() for more complete examples.
 217
 218   See sd_notify(3) for more information.
 219 */
 220 int sd_notify(int unset_environment, const char *state) _sd_hidden_;
 221
 222 /*
 223   Similar to sd_notify() but takes a format string.
 224
 225   Example 1: A daemon could send the following after initialization:
 226
 227      sd_notifyf(0, "READY=1\n"
 228                    "STATUS=Processing requests...\n"
 229                    "MAINPID=%lu",
 230                    (unsigned long) getpid());
 231
 232   Example 2: A daemon could send the following shortly before
 233   exiting, on failure:
 234
 235      sd_notifyf(0, "STATUS=Failed to start up: %s\n"
 236                    "ERRNO=%i",
 237                    strerror(errno),
 238                    errno);
 239
 240   See sd_notifyf(3) for more information.
 241 */
 242 int sd_notifyf(int unset_environment, const char *format, ...) _sd_printf_attr_(2,3) _sd_hidden_;
 243
 244 /*
 245   Returns > 0 if the system was booted with systemd. Returns < 0 on
 246   error. Returns 0 if the system was not booted with systemd. Note
 247   that all of the functions above handle non-systemd boots just
 248   fine. You should NOT protect them with a call to this function. Also
 249   note that this function checks whether the system, not the user
 250   session is controlled by systemd. However the functions above work
 251   for both session and system services.
 252
 253   See sd_booted(3) for more information.
 254 */
 255 int sd_booted(void) _sd_hidden_;
 256
 257 #ifdef __cplusplus
 258 }
 259 #endif
 260
 261 #endif