process.h

   1 /* Process handling
   2  *
   3  * Copyright © 2013, Benoît Knecht <benoit.knecht@fsfe.org>
   4  *
   5  * All rights reserved.
   6  *
   7  * Redistribution and use in source and binary forms, with or without
   8  * modification, are permitted provided that the following conditions are met:
   9  *     * Redistributions of source code must retain the above copyright
  10  *       notice, this list of conditions and the following disclaimer.
  11  *     * Redistributions in binary form must reproduce the above copyright
  12  *       notice, this list of conditions and the following disclaimer in the
  13  *       documentation and/or other materials provided with the distribution.
  14  *     * The name of the author may not be used to endorse or promote products
  15  *       derived from this software without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  18  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
  21  * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
  22  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
  23  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
  24  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
  25  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  26  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  27  * POSSIBILITY OF SUCH DAMAGE.
  28  */
  29 #ifndef __PROCESS_H__
  30 #define __PROCESS_H__
  31
  32 #include <unistd.h>
  33 #include "clients.h"
  34
  35 struct child {
  36         pid_t pid;
  37         time_t age;
  38         struct client_cache_s *client;
  39 };
  40
  41 extern struct child *children;
  42 extern int number_of_children;
  43
  44 /**
  45  * Fork a new child (just like fork()) but keep track of how many childs are
  46  * already running, and refuse fo fork if there are too many.
  47  * @return -1 if it couldn't fork, 0 in the child process, the pid of the
  48  *         child process in the parent process.
  49  */
  50 pid_t process_fork(struct client_cache_s *client);
  51
  52 /**
  53  * Handler to be called upon receiving SIGCHLD. This signal is received by the
  54  * parent process when a child terminates, and this handler updates the number
  55  * of running childs accordingly.
  56  * @param signal The signal number.
  57  */
  58 void process_handle_child_termination(int signal);
  59
  60 /**
  61  * Daemonize the current process by forking itself and redirecting standard
  62  * input, standard output and standard error to /dev/null.
  63  * @return The pid of the process.
  64  */
  65 int process_daemonize(void);
  66
  67 /**
  68  * Check if the process corresponding to the pid found in the pid file is
  69  * running.
  70  * @param fname The path to the pid file.
  71  * @return 0 if no other instance is running, -1 if the file name is invalid,
  72  *         -2 if another instance is running.
  73  */
  74 int process_check_if_running(const char *fname);
  75
  76 /**
  77  * Kill all child processes
  78  */
  79 void process_reap_children(void);
  80
  81 #endif // __PROCESS_H__