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include/sd-daemon.h
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00001 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
00002 
00003 #ifndef foosddaemonhfoo
00004 #define foosddaemonhfoo
00005 
00006 /***
00007   Copyright 2010 Lennart Poettering
00008 
00009   Permission is hereby granted, free of charge, to any person
00010   obtaining a copy of this software and associated documentation files
00011   (the "Software"), to deal in the Software without restriction,
00012   including without limitation the rights to use, copy, modify, merge,
00013   publish, distribute, sublicense, and/or sell copies of the Software,
00014   and to permit persons to whom the Software is furnished to do so,
00015   subject to the following conditions:
00016 
00017   The above copyright notice and this permission notice shall be
00018   included in all copies or substantial portions of the Software.
00019 
00020   THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
00021   EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
00022   MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
00023   NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
00024   BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
00025   ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
00026   CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
00027   SOFTWARE.
00028 ***/
00029 
00030 #include <sys/types.h>
00031 #include <inttypes.h>
00032 
00033 #ifdef __cplusplus
00034 extern "C" {
00035 #endif
00036 
00037 /*
00038   Reference implementation of a few systemd related interfaces for
00039   writing daemons. These interfaces are trivial to implement. To
00040   simplify porting we provide this reference implementation.
00041   Applications are welcome to reimplement the algorithms described
00042   here if they do not want to include these two source files.
00043 
00044   The following functionality is provided:
00045 
00046   - Support for logging with log levels on stderr
00047   - File descriptor passing for socket-based activation
00048   - Daemon startup and status notification
00049   - Detection of systemd boots
00050 
00051   You may compile this with -DDISABLE_SYSTEMD to disable systemd
00052   support. This makes all those calls NOPs that are directly related to
00053   systemd (i.e. only sd_is_xxx() will stay useful).
00054 
00055   Since this is drop-in code we don't want any of our symbols to be
00056   exported in any case. Hence we declare hidden visibility for all of
00057   them.
00058 
00059   You may find an up-to-date version of these source files online:
00060 
00061   http://cgit.freedesktop.org/systemd/plain/src/sd-daemon.h
00062   http://cgit.freedesktop.org/systemd/plain/src/sd-daemon.c
00063 
00064   This should compile on non-Linux systems, too, but with the
00065   exception of the sd_is_xxx() calls all functions will become NOPs.
00066 
00067   See sd-daemon(7) for more information.
00068 */
00069 
00070 #ifndef _sd_printf_attr_
00071 #if __GNUC__ >= 4
00072 #define _sd_printf_attr_(a,b) __attribute__ ((format (printf, a, b)))
00073 #else
00074 #define _sd_printf_attr_(a,b)
00075 #endif
00076 #endif
00077 
00078 #ifndef _sd_hidden_
00079 #if (__GNUC__ >= 4) && !defined(SD_EXPORT_SYMBOLS)
00080 #define _sd_hidden_ __attribute__ ((visibility("hidden")))
00081 #else
00082 #define _sd_hidden_
00083 #endif
00084 #endif
00085 
00086 /*
00087   Log levels for usage on stderr:
00088 
00089           fprintf(stderr, SD_NOTICE "Hello World!\n");
00090 
00091   This is similar to printk() usage in the kernel.
00092 */
00093 #define SD_EMERG   "<0>"  /* system is unusable */
00094 #define SD_ALERT   "<1>"  /* action must be taken immediately */
00095 #define SD_CRIT    "<2>"  /* critical conditions */
00096 #define SD_ERR     "<3>"  /* error conditions */
00097 #define SD_WARNING "<4>"  /* warning conditions */
00098 #define SD_NOTICE  "<5>"  /* normal but significant condition */
00099 #define SD_INFO    "<6>"  /* informational */
00100 #define SD_DEBUG   "<7>"  /* debug-level messages */
00101 
00102 /* The first passed file descriptor is fd 3 */
00103 #define SD_LISTEN_FDS_START 3
00104 
00105 /*
00106   Returns how many file descriptors have been passed, or a negative
00107   errno code on failure. Optionally, removes the $LISTEN_FDS and
00108   $LISTEN_PID file descriptors from the environment (recommended, but
00109   problematic in threaded environments). If r is the return value of
00110   this function you'll find the file descriptors passed as fds
00111   SD_LISTEN_FDS_START to SD_LISTEN_FDS_START+r-1. Returns a negative
00112   errno style error code on failure. This function call ensures that
00113   the FD_CLOEXEC flag is set for the passed file descriptors, to make
00114   sure they are not passed on to child processes. If FD_CLOEXEC shall
00115   not be set, the caller needs to unset it after this call for all file
00116   descriptors that are used.
00117 
00118   See sd_listen_fds(3) for more information.
00119 */
00120 int sd_listen_fds(int unset_environment) _sd_hidden_;
00121 
00122 /*
00123   Helper call for identifying a passed file descriptor. Returns 1 if
00124   the file descriptor is a FIFO in the file system stored under the
00125   specified path, 0 otherwise. If path is NULL a path name check will
00126   not be done and the call only verifies if the file descriptor
00127   refers to a FIFO. Returns a negative errno style error code on
00128   failure.
00129 
00130   See sd_is_fifo(3) for more information.
00131 */
00132 int sd_is_fifo(int fd, const char *path) _sd_hidden_;
00133 
00134 /*
00135   Helper call for identifying a passed file descriptor. Returns 1 if
00136   the file descriptor is a socket of the specified family (AF_INET,
00137   ...) and type (SOCK_DGRAM, SOCK_STREAM, ...), 0 otherwise. If
00138   family is 0 a socket family check will not be done. If type is 0 a
00139   socket type check will not be done and the call only verifies if
00140   the file descriptor refers to a socket. If listening is > 0 it is
00141   verified that the socket is in listening mode. (i.e. listen() has
00142   been called) If listening is == 0 it is verified that the socket is
00143   not in listening mode. If listening is < 0 no listening mode check
00144   is done. Returns a negative errno style error code on failure.
00145 
00146   See sd_is_socket(3) for more information.
00147 */
00148 int sd_is_socket(int fd, int family, int type, int listening) _sd_hidden_;
00149 
00150 /*
00151   Helper call for identifying a passed file descriptor. Returns 1 if
00152   the file descriptor is an Internet socket, of the specified family
00153   (either AF_INET or AF_INET6) and the specified type (SOCK_DGRAM,
00154   SOCK_STREAM, ...), 0 otherwise. If version is 0 a protocol version
00155   check is not done. If type is 0 a socket type check will not be
00156   done. If port is 0 a socket port check will not be done. The
00157   listening flag is used the same way as in sd_is_socket(). Returns a
00158   negative errno style error code on failure.
00159 
00160   See sd_is_socket_inet(3) for more information.
00161 */
00162 int sd_is_socket_inet(int fd, int family, int type, int listening, uint16_t port) _sd_hidden_;
00163 
00164 /*
00165   Helper call for identifying a passed file descriptor. Returns 1 if
00166   the file descriptor is an AF_UNIX socket of the specified type
00167   (SOCK_DGRAM, SOCK_STREAM, ...) and path, 0 otherwise. If type is 0
00168   a socket type check will not be done. If path is NULL a socket path
00169   check will not be done. For normal AF_UNIX sockets set length to
00170   0. For abstract namespace sockets set length to the length of the
00171   socket name (including the initial 0 byte), and pass the full
00172   socket path in path (including the initial 0 byte). The listening
00173   flag is used the same way as in sd_is_socket(). Returns a negative
00174   errno style error code on failure.
00175 
00176   See sd_is_socket_unix(3) for more information.
00177 */
00178 int sd_is_socket_unix(int fd, int type, int listening, const char *path, size_t length) _sd_hidden_;
00179 
00180 /*
00181   Informs systemd about changed daemon state. This takes a number of
00182   newline separated environment-style variable assignments in a
00183   string. The following variables are known:
00184 
00185      READY=1      Tells systemd that daemon startup is finished (only
00186                   relevant for services of Type=notify). The passed
00187                   argument is a boolean "1" or "0". Since there is
00188                   little value in signaling non-readiness the only
00189                   value daemons should send is "READY=1".
00190 
00191      STATUS=...   Passes a single-line status string back to systemd
00192                   that describes the daemon state. This is free-from
00193                   and can be used for various purposes: general state
00194                   feedback, fsck-like programs could pass completion
00195                   percentages and failing programs could pass a human
00196                   readable error message. Example: "STATUS=Completed
00197                   66% of file system check..."
00198 
00199      ERRNO=...    If a daemon fails, the errno-style error code,
00200                   formatted as string. Example: "ERRNO=2" for ENOENT.
00201 
00202      BUSERROR=... If a daemon fails, the D-Bus error-style error
00203                   code. Example: "BUSERROR=org.freedesktop.DBus.Error.TimedOut"
00204 
00205      MAINPID=...  The main pid of a daemon, in case systemd did not
00206                   fork off the process itself. Example: "MAINPID=4711"
00207 
00208   Daemons can choose to send additional variables. However, it is
00209   recommended to prefix variable names not listed above with X_.
00210 
00211   Returns a negative errno-style error code on failure. Returns > 0
00212   if systemd could be notified, 0 if it couldn't possibly because
00213   systemd is not running.
00214 
00215   Example: When a daemon finished starting up, it could issue this
00216   call to notify systemd about it:
00217 
00218      sd_notify(0, "READY=1");
00219 
00220   See sd_notifyf() for more complete examples.
00221 
00222   See sd_notify(3) for more information.
00223 */
00224 int sd_notify(int unset_environment, const char *state) _sd_hidden_;
00225 
00226 /*
00227   Similar to sd_notify() but takes a format string.
00228 
00229   Example 1: A daemon could send the following after initialization:
00230 
00231      sd_notifyf(0, "READY=1\n"
00232                    "STATUS=Processing requests...\n"
00233                    "MAINPID=%lu",
00234                    (unsigned long) getpid());
00235 
00236   Example 2: A daemon could send the following shortly before
00237   exiting, on failure:
00238 
00239      sd_notifyf(0, "STATUS=Failed to start up: %s\n"
00240                    "ERRNO=%i",
00241                    strerror(errno),
00242                    errno);
00243 
00244   See sd_notifyf(3) for more information.
00245 */
00246 int sd_notifyf(int unset_environment, const char *format, ...) _sd_printf_attr_(2,3) _sd_hidden_;
00247 
00248 /*
00249   Returns > 0 if the system was booted with systemd. Returns < 0 on
00250   error. Returns 0 if the system was not booted with systemd. Note
00251   that all of the functions above handle non-systemd boots just
00252   fine. You should NOT protect them with a call to this function. Also
00253   note that this function checks whether the system, not the user
00254   session is controlled by systemd. However the functions above work
00255   for both user and system services.
00256 
00257   See sd_booted(3) for more information.
00258 */
00259 int sd_booted(void) _sd_hidden_;
00260 
00261 #ifdef __cplusplus
00262 }
00263 #endif
00264 
00265 #endif