/** * Copyright © 2015 Mattias Andrée * * Permission is hereby granted, free of charge, to any person obtaining a * copy of this software and associated documentation files (the "Software"), * to deal in the Software without restriction, including without limitation * the rights to use, copy, modify, merge, publish, distribute, sublicense, * and/or sell copies of the Software, and to permit persons to whom the * Software is furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER * DEALINGS IN THE SOFTWARE. */ /** * Leave all opened files open. */ #define DAEMONISE_NO_CLOSE 1 /** * Leave all signal handlers rather than * appling default signal handlers. */ #define DAEMONISE_NO_SIG_DFL 2 /** * Leave the signal block mask as-is. */ #define DAEMONISE_KEEP_SIGMASK 4 /** * Do not remove malformatted environment entries. */ #define DAEMONISE_KEEP_ENVIRON 8 /** * Do not set umask to zero. */ #define DAEMONISE_KEEP_UMASK 16 /** * Do not create a PID file. */ #define DAEMONISE_NO_PID_FILE 32 /** * Do not close stderr even if it is * a terminal device. * * Cannot be combined with `DAEMONISE_KEEP_STDERR`. */ #define DAEMONISE_KEEP_STDERR 64 /** * Close stderr even if it is * not a terminal device. * * Cannot be combined with `DAEMONISE_KEEP_STDERR`. */ #define DAEMONISE_CLOSE_STDERR 128 /** * Do not close stdin. */ #define DAEMONISE_KEEP_STDIN 256 /** * Do not close stdout. */ #define DAEMONISE_KEEP_STDOUT 512 /** * Daemonise the process. This means to: * * - close all file descritors except for those to * stdin, stdout, and stderr, * * - remove all custom signal handlers, and apply * the default handlers. * * - unblock all signals, * * - remove all malformatted entries in the * environment (this not containing an '=',) * * - set the umask to zero, to be ensure that all * file permissions are set as specified, * * - change directory to '/', to ensure that the * process does not block any mountpoint from being * unmounted, * * - fork to become a background process, * * - temporarily become a session leader to ensure * that the process does not have a controlling * terminal. * * - fork again to become a child of the daemon * supervisor, (subreaper could however be in the * say, so one should not merely rely on this when * writing a daemon supervisor,) (the first child * shall exit after this,) * * - create, exclusively, a PID file to stop the daemon * to be being run twice concurrently, and to let * the daemon supervicer know the process ID of the * daemon, * * - redirect stdin and stdout to /dev/null, * as well as stderr if it is currently directed * to a terminal, and * * - exit in the original process to let the daemon * supervisor know that the daemon has been * initialised. * * Before calling this function, you should remove any * environment variable that could negatively impact * the runtime of the process. * * After calling this function, you should remove * unnecessary privileges. * * Do not try do continue the process in failure unless * you make sure to only do this in the original process. * But not that things will not necessarily be as when * you make the function call. The process can have become * partially deamonised. * * If $XDG_RUNTIME_DIR is set and is not empty, its value * should be used instead of /run for the runtime data-files * directory, in which the PID file is stored. * * @etymology (Daemonise) the process! * * @param name The name of the daemon. Use a hardcoded value, * not the process name. Must not be `NULL`. * @param flags Flags to modify the behaviour of the function. * A bitwise OR combination of the constants: * - `DAEMONISE_NO_CLOSE` * - `DAEMONISE_NO_SIG_DFL` * - `DAEMONISE_KEEP_SIGMASK` * - `DAEMONISE_KEEP_ENVIRON` * - `DAEMONISE_KEEP_UMASK` * - `DAEMONISE_NO_PID_FILE` * - `DAEMONISE_KEEP_STDERR` * - `DAEMONISE_CLOSE_STDERR` * - `DAEMONISE_KEEP_STDIN` * - `DAEMONISE_KEEP_STDOUT` * @return Zero on success, -1 on error. * * @throws EEXIST The PID file already exists on the system. * Unless your daemon supervisor removs old * PID files, this could mean that the daemon * has exited without removing the PID file. * @throws Any error specified for signal(3). * @throws Any error specified for sigemptyset(3). * @throws Any error specified for sigprocmask(3). * @throws Any error specified for chdir(3). * @throws Any error specified for pipe(3). * @throws Any error specified for dup2(3). * @throws Any error specified for fork(3). * @throws Any error specified for setsid(3). * @throws Any error specified for open(3). * * @since Always. */ int daemonise(const char* name, int flags); /** * Remove the PID file created by `daemonise`. This shall * always be called before exiting after calling `daemonise`, * even if it failed. * * This is a slibc extension. * * @etymology (Un)link PID file created by `(daemonise)`! * * @return Zero on success, -1 on error. * * @throws Any error specified for unlink(3). * * @since Always. */ int undaemonise(void);