src/systemd/sd-daemon.h

   1 #ifndef foosddaemonhfoo
   2 #define foosddaemonhfoo
   3
   4 /***
   5   This file is part of systemd.
   6
   7   Copyright 2013 Lennart Poettering
   8
   9   systemd is free software; you can redistribute it and/or modify it
  10   under the terms of the GNU Lesser General Public License as published by
  11   the Free Software Foundation; either version 2.1 of the License, or
  12   (at your option) any later version.
  13
  14   systemd is distributed in the hope that it will be useful, but
  15   WITHOUT ANY WARRANTY; without even the implied warranty of
  16   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  17   Lesser General Public License for more details.
  18
  19   You should have received a copy of the GNU Lesser General Public License
  20   along with systemd; If not, see <http://www.gnu.org/licenses/>.
  21 ***/
  22
  23 #include <inttypes.h>
  24 #include <sys/types.h>
  25
  26 #include "_sd-common.h"
  27
  28 _SD_BEGIN_DECLARATIONS;
  29
  30 /*
  31   The following functionality is provided:
  32
  33   - Support for logging with log levels on stderr
  34   - File descriptor passing for socket-based activation
  35   - Daemon startup and status notification
  36   - Detection of systemd boots
  37
  38   See sd-daemon(3) for more information.
  39 */
  40
  41 /*
  42   Log levels for usage on stderr:
  43
  44           fprintf(stderr, SD_NOTICE "Hello World!\n");
  45
  46   This is similar to printk() usage in the kernel.
  47 */
  48 #define SD_EMERG   "<0>"  /* system is unusable */
  49 #define SD_ALERT   "<1>"  /* action must be taken immediately */
  50 #define SD_CRIT    "<2>"  /* critical conditions */
  51 #define SD_ERR     "<3>"  /* error conditions */
  52 #define SD_WARNING "<4>"  /* warning conditions */
  53 #define SD_NOTICE  "<5>"  /* normal but significant condition */
  54 #define SD_INFO    "<6>"  /* informational */
  55 #define SD_DEBUG   "<7>"  /* debug-level messages */
  56
  57 /* The first passed file descriptor is fd 3 */
  58 #define SD_LISTEN_FDS_START 3
  59
  60 /*
  61   Returns how many file descriptors have been passed, or a negative
  62   errno code on failure. Optionally, removes the $LISTEN_FDS and
  63   $LISTEN_PID file descriptors from the environment (recommended, but
  64   problematic in threaded environments). If r is the return value of
  65   this function you'll find the file descriptors passed as fds
  66   SD_LISTEN_FDS_START to SD_LISTEN_FDS_START+r-1. Returns a negative
  67   errno style error code on failure. This function call ensures that
  68   the FD_CLOEXEC flag is set for the passed file descriptors, to make
  69   sure they are not passed on to child processes. If FD_CLOEXEC shall
  70   not be set, the caller needs to unset it after this call for all file
  71   descriptors that are used.
  72
  73   See sd_listen_fds(3) for more information.
  74 */
  75 int sd_listen_fds(int unset_environment);
  76
  77 int sd_listen_fds_with_names(int unset_environment, char ***names);
  78
  79 /*
  80   Helper call for identifying a passed file descriptor. Returns 1 if
  81   the file descriptor is a FIFO in the file system stored under the
  82   specified path, 0 otherwise. If path is NULL a path name check will
  83   not be done and the call only verifies if the file descriptor
  84   refers to a FIFO. Returns a negative errno style error code on
  85   failure.
  86
  87   See sd_is_fifo(3) for more information.
  88 */
  89 int sd_is_fifo(int fd, const char *path);
  90
  91 /*
  92   Helper call for identifying a passed file descriptor. Returns 1 if
  93   the file descriptor is a special character device on the file
  94   system stored under the specified path, 0 otherwise.
  95   If path is NULL a path name check will not be done and the call
  96   only verifies if the file descriptor refers to a special character.
  97   Returns a negative errno style error code on failure.
  98
  99   See sd_is_special(3) for more information.
 100 */
 101 int sd_is_special(int fd, const char *path);
 102
 103 /*
 104   Helper call for identifying a passed file descriptor. Returns 1 if
 105   the file descriptor is a socket of the specified family (AF_INET,
 106   ...) and type (SOCK_DGRAM, SOCK_STREAM, ...), 0 otherwise. If
 107   family is 0 a socket family check will not be done. If type is 0 a
 108   socket type check will not be done and the call only verifies if
 109   the file descriptor refers to a socket. If listening is > 0 it is
 110   verified that the socket is in listening mode. (i.e. listen() has
 111   been called) If listening is == 0 it is verified that the socket is
 112   not in listening mode. If listening is < 0 no listening mode check
 113   is done. Returns a negative errno style error code on failure.
 114
 115   See sd_is_socket(3) for more information.
 116 */
 117 int sd_is_socket(int fd, int family, int type, int listening);
 118
 119 /*
 120   Helper call for identifying a passed file descriptor. Returns 1 if
 121   the file descriptor is an Internet socket, of the specified family
 122   (either AF_INET or AF_INET6) and the specified type (SOCK_DGRAM,
 123   SOCK_STREAM, ...), 0 otherwise. If version is 0 a protocol version
 124   check is not done. If type is 0 a socket type check will not be
 125   done. If port is 0 a socket port check will not be done. The
 126   listening flag is used the same way as in sd_is_socket(). Returns a
 127   negative errno style error code on failure.
 128
 129   See sd_is_socket_inet(3) for more information.
 130 */
 131 int sd_is_socket_inet(int fd, int family, int type, int listening, uint16_t port);
 132
 133 /*
 134   Helper call for identifying a passed file descriptor. Returns 1 if
 135   the file descriptor is an AF_UNIX socket of the specified type
 136   (SOCK_DGRAM, SOCK_STREAM, ...) and path, 0 otherwise. If type is 0
 137   a socket type check will not be done. If path is NULL a socket path
 138   check will not be done. For normal AF_UNIX sockets set length to
 139   0. For abstract namespace sockets set length to the length of the
 140   socket name (including the initial 0 byte), and pass the full
 141   socket path in path (including the initial 0 byte). The listening
 142   flag is used the same way as in sd_is_socket(). Returns a negative
 143   errno style error code on failure.
 144
 145   See sd_is_socket_unix(3) for more information.
 146 */
 147 int sd_is_socket_unix(int fd, int type, int listening, const char *path, size_t length);
 148
 149 /*
 150   Helper call for identifying a passed file descriptor. Returns 1 if
 151   the file descriptor is a POSIX Message Queue of the specified name,
 152   0 otherwise. If path is NULL a message queue name check is not
 153   done. Returns a negative errno style error code on failure.
 154
 155   See sd_is_mq(3) for more information.
 156 */
 157 int sd_is_mq(int fd, const char *path);
 158
 159 /*
 160   Informs systemd about changed daemon state. This takes a number of
 161   newline separated environment-style variable assignments in a
 162   string. The following variables are known:
 163
 164      READY=1      Tells systemd that daemon startup is finished (only
 165                   relevant for services of Type=notify). The passed
 166                   argument is a boolean "1" or "0". Since there is
 167                   little value in signaling non-readiness the only
 168                   value daemons should send is "READY=1".
 169
 170      STATUS=...   Passes a single-line status string back to systemd
 171                   that describes the daemon state. This is free-form
 172                   and can be used for various purposes: general state
 173                   feedback, fsck-like programs could pass completion
 174                   percentages and failing programs could pass a human
 175                   readable error message. Example: "STATUS=Completed
 176                   66% of file system check..."
 177
 178      ERRNO=...    If a daemon fails, the errno-style error code,
 179                   formatted as string. Example: "ERRNO=2" for ENOENT.
 180
 181      BUSERROR=... If a daemon fails, the D-Bus error-style error
 182                   code. Example: "BUSERROR=org.freedesktop.DBus.Error.TimedOut"
 183
 184      MAINPID=...  The main pid of a daemon, in case systemd did not
 185                   fork off the process itself. Example: "MAINPID=4711"
 186
 187      WATCHDOG=1   Tells systemd to update the watchdog timestamp.
 188                   Services using this feature should do this in
 189                   regular intervals. A watchdog framework can use the
 190                   timestamps to detect failed services. Also see
 191                   sd_watchdog_enabled() below.
 192
 193      FDSTORE=1    Store the file descriptors passed along with the
 194                   message in the per-service file descriptor store,
 195                   and pass them to the main process again on next
 196                   invocation. This variable is only supported with
 197                   sd_pid_notify_with_fds().
 198
 199      WATCHDOG_USEC=...
 200                   Reset watchdog_usec value during runtime.
 201                   To reset watchdog_usec value, start the service again.
 202                   Example: "WATCHDOG_USEC=20000000"
 203
 204   Daemons can choose to send additional variables. However, it is
 205   recommended 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);
 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_(2,3);
 243
 244 /*
 245   Similar to sd_notify(), but send the message on behalf of another
 246   process, if the appropriate permissions are available.
 247 */
 248 int sd_pid_notify(pid_t pid, int unset_environment, const char *state);
 249
 250 /*
 251   Similar to sd_notifyf(), but send the message on behalf of another
 252   process, if the appropriate permissions are available.
 253 */
 254 int sd_pid_notifyf(pid_t pid, int unset_environment, const char *format, ...) _sd_printf_(3,4);
 255
 256 /*
 257   Similar to sd_pid_notify(), but also passes the specified fd array
 258   to the service manager for storage. This is particularly useful for
 259   FDSTORE=1 messages.
 260 */
 261 int sd_pid_notify_with_fds(pid_t pid, int unset_environment, const char *state, const int *fds, unsigned n_fds);
 262
 263 /*
 264   Returns > 0 if the system was booted with systemd. Returns < 0 on
 265   error. Returns 0 if the system was not booted with systemd. Note
 266   that all of the functions above handle non-systemd boots just
 267   fine. You should NOT protect them with a call to this function. Also
 268   note that this function checks whether the system, not the user
 269   session is controlled by systemd. However the functions above work
 270   for both user and system services.
 271
 272   See sd_booted(3) for more information.
 273 */
 274 int sd_booted(void);
 275
 276 /*
 277   Returns > 0 if the service manager expects watchdog keep-alive
 278   events to be sent regularly via sd_notify(0, "WATCHDOG=1"). Returns
 279   0 if it does not expect this. If the usec argument is non-NULL
 280   returns the watchdog timeout in µs after which the service manager
 281   will act on a process that has not sent a watchdog keep alive
 282   message. This function is useful to implement services that
 283   recognize automatically if they are being run under supervision of
 284   systemd with WatchdogSec= set. It is recommended for clients to
 285   generate keep-alive pings via sd_notify(0, "WATCHDOG=1") every half
 286   of the returned time.
 287
 288   See sd_watchdog_enabled(3) for more information.
 289 */
 290 int sd_watchdog_enabled(int unset_environment, uint64_t *usec);
 291
 292 _SD_END_DECLARATIONS;
 293
 294 #endif