src/application.c

   1 /* Utility functions to setup applications */
   2 /*
   3  * (C) 2010 by Harald Welte <laforge@gnumonks.org>
   4  * (C) 2011 by Holger Hans Peter Freyther
   5  *
   6  * All Rights Reserved
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License as published by
  10  * the Free Software Foundation; either version 2 of the License, or
  11  * (at your option) any later version.
  12  *
  13  * This program is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16  * GNU General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU General Public License along
  19  * with this program; if not, write to the Free Software Foundation, Inc.,
  20  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  21  *
  22  */
  23
  24 /*! \file application.c
  25  *  \brief Routines for helping with the osmocom application setup.
  26  */
  27
  28 /*! \mainpage libosmocore Documentation
  29  * \section sec_intro Introduction
  30  * This library is a collection of common code used in various
  31  * sub-projects inside the Osmocom family of projects.  It includes a
  32  * logging framework, select() loop abstraction, timers with callbacks,
  33  * bit vectors, bit packing/unpacking, convolutional decoding, GSMTAP, a
  34  * generic plugin interface, statistics counters, memory allocator,
  35  * socket abstraction, message buffers, etc.
  36  * \n\n
  37  * Please note that C language projects inside Osmocom are typically
  38  * single-threaded event-loop state machine designs.  As such,
  39  * routines in libosmocore are not thread-safe.  If you must use them in
  40  * a multi-threaded context, you have to add your own locking.
  41  *
  42  * \section sec_copyright Copyright and License
  43  * Copyright © 2008-2011 - Harald Welte, Holger Freyther and contributors\n
  44  * All rights reserved. \n\n
  45  * The source code of libosmocore is licensed under the terms of the GNU
  46  * General Public License as published by the Free Software Foundation;
  47  * either version 2 of the License, or (at your option) any later
  48  * version.\n
  49  * See <http://www.gnu.org/licenses/> or COPYING included in the source
  50  * code package istelf.\n
  51  * The information detailed here is provided AS IS with NO WARRANTY OF
  52  * ANY KIND, INCLUDING THE WARRANTY OF DESIGN, MERCHANTABILITY AND
  53  * FITNESS FOR A PARTICULAR PURPOSE.
  54  * \n\n
  55  *
  56  * \section sec_contact Contact and Support
  57  * Community-based support is available at the OpenBSC mailing list
  58  * <http://lists.osmocom.org/mailman/listinfo/openbsc>\n
  59  * Commercial support options available upon request from
  60  * <http://sysmocom.de/>
  61  */
  62
  63 #include <osmocom/core/application.h>
  64 #include <osmocom/core/logging.h>
  65
  66 #include <signal.h>
  67 #include <stdio.h>
  68 #include <stdlib.h>
  69 #include <unistd.h>
  70 #include <errno.h>
  71 #include <sys/stat.h>
  72
  73 struct log_target *osmo_stderr_target;
  74
  75 /*! \brief Ignore \ref SIGPIPE, \ref SIGALRM, \ref SIGHUP and \ref SIGIO */
  76 void osmo_init_ignore_signals(void)
  77 {
  78         /* Signals that by default would terminate */
  79         signal(SIGPIPE, SIG_IGN);
  80         signal(SIGALRM, SIG_IGN);
  81         signal(SIGHUP, SIG_IGN);
  82         signal(SIGIO, SIG_IGN);
  83 }
  84
  85 /*! \brief Initialize the osmocom logging framework
  86  *  \param[in] log_info Array of available logging sub-systems
  87  *  \returns 0 on success, -1 in case of error
  88  *
  89  * This function initializes the osmocom logging systems.  It also
  90  * creates the default (stderr) logging target.
  91  */
  92 int osmo_init_logging(const struct log_info *log_info)
  93 {
  94         log_init(log_info, NULL);
  95         osmo_stderr_target = log_target_create_stderr();
  96         if (!osmo_stderr_target)
  97                 return -1;
  98
  99         log_add_target(osmo_stderr_target);
 100         log_set_all_filter(osmo_stderr_target, 1);
 101         return 0;
 102 }
 103
 104 /*! \brief Turn the current process into a background daemon
 105  *
 106  * This function will fork the process, exit the parent and set umask,
 107  * create a new session, close stdin/stdout/stderr and chdir to /tmp
 108  */
 109 int osmo_daemonize(void)
 110 {
 111         int rc;
 112         pid_t pid, sid;
 113
 114         /* Check if parent PID == init, in which case we are already a daemon */
 115         if (getppid() == 1)
 116                 return -EEXIST;
 117
 118         /* Fork from the parent process */
 119         pid = fork();
 120         if (pid < 0) {
 121                 /* some error happened */
 122                 return pid;
 123         }
 124
 125         if (pid > 0) {
 126                 /* if we have received a positive PID, then we are the parent
 127                  * and can exit */
 128                 exit(0);
 129         }
 130
 131         /* FIXME: do we really want this? */
 132         umask(0);
 133
 134         /* Create a new session and set process group ID */
 135         sid = setsid();
 136         if (sid < 0)
 137                 return sid;
 138
 139         /* Change to the /tmp directory, which prevents the CWD from being locked
 140          * and unable to remove it */
 141         rc = chdir("/tmp");
 142         if (rc < 0)
 143                 return rc;
 144
 145         /* Redirect stdio to /dev/null */
 146 /* since C89/C99 says stderr is a macro, we can safely do this! */
 147 #ifdef stderr
 148         freopen("/dev/null", "r", stdin);
 149         freopen("/dev/null", "w", stdout);
 150         freopen("/dev/null", "w", stderr);
 151 #endif
 152
 153         return 0;
 154 }