testd.c

This is an example for the usage of libdaemon

00001 /* $Id: testd.c 101 2005-11-18 20:39:12Z lennart $ */
00002 
00003 /*
00004  * This file is part of libdaemon.
00005  *
00006  * libdaemon is free software; you can redistribute it and/or modify
00007  * it under the terms of the GNU Lesser General Public License as
00008  * published by the Free Software Foundation; either version 2.1 of
00009  * the License, or (at your option) any later version.
00010  *
00011  * libdaemon is distributed in the hope that it will be useful, but
00012  * WITHOUT ANY WARRANTY; without even the implied warranty of
00013  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00014  * Lesser General Public License for more details.
00015  *
00016  * You should have received a copy of the GNU Lesser General Public
00017  * License along with libdaemon; if not, write to the Free Software
00018  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
00019  * 02110-1301 USA
00020  */
00021 
00022 #include <signal.h>
00023 #include <errno.h>
00024 #include <string.h>
00025 #include <sys/types.h>
00026 #include <sys/time.h>
00027 #include <sys/unistd.h>
00028 #include <sys/select.h>
00029 
00030 #include <libdaemon/dfork.h>
00031 #include <libdaemon/dsignal.h>
00032 #include <libdaemon/dlog.h>
00033 #include <libdaemon/dpid.h>
00034 #include <libdaemon/dexec.h>
00035 
00036 int main(int argc, char *argv[]) {
00037     pid_t pid;
00038 
00039     /* Set indetification string for the daemon for both syslog and PID file */
00040     daemon_pid_file_ident = daemon_log_ident = daemon_ident_from_argv0(argv[0]);
00041 
00042     /* Check if we are called with -k parameter */
00043     if (argc >= 2 && !strcmp(argv[1], "-k")) {
00044         int ret;
00045 
00046         /* Kill daemon with SIGINT */
00047         
00048         /* Check if the new function daemon_pid_file_kill_wait() is available, if it is, use it. */
00049 #ifdef DAEMON_PID_FILE_KILL_WAIT_AVAILABLE        
00050         if ((ret = daemon_pid_file_kill_wait(SIGINT, 5)) < 0)
00051 #else
00052         if ((ret = daemon_pid_file_kill(SIGINT)) < 0)
00053 #endif
00054             daemon_log(LOG_WARNING, "Failed to kill daemon");
00055         
00056         return ret < 0 ? 1 : 0;
00057     }
00058 
00059     /* Check that the daemon is not rung twice a the same time */
00060     if ((pid = daemon_pid_file_is_running()) >= 0) {
00061         daemon_log(LOG_ERR, "Daemon already running on PID file %u", pid);
00062         return 1;
00063         
00064     }
00065 
00066     /* Prepare for return value passing from the initialization procedure of the daemon process */
00067     daemon_retval_init();
00068 
00069     /* Do the fork */
00070     if ((pid = daemon_fork()) < 0) {
00071 
00072         /* Exit on error */
00073         daemon_retval_done();
00074         return 1;
00075         
00076     } else if (pid) { /* The parent */
00077         int ret;
00078 
00079         /* Wait for 20 seconds for the return value passed from the daemon process */
00080         if ((ret = daemon_retval_wait(20)) < 0) {
00081             daemon_log(LOG_ERR, "Could not recieve return value from daemon process.");
00082             return 255;
00083         }
00084 
00085         daemon_log(ret != 0 ? LOG_ERR : LOG_INFO, "Daemon returned %i as return value.", ret);
00086         return ret;
00087         
00088     } else { /* The daemon */
00089         int fd, quit = 0;
00090         fd_set fds;
00091 
00092         /* Create the PID file */
00093         if (daemon_pid_file_create() < 0) {
00094             daemon_log(LOG_ERR, "Could not create PID file (%s).", strerror(errno));
00095 
00096             /* Send the error condition to the parent process */
00097             daemon_retval_send(1);
00098             goto finish;
00099         }
00100 
00101         /* Initialize signal handling */
00102         if (daemon_signal_init(SIGINT, SIGQUIT, SIGHUP, 0) < 0) {
00103             daemon_log(LOG_ERR, "Could not register signal handlers (%s).", strerror(errno));
00104             daemon_retval_send(2);
00105             goto finish;
00106         }
00107         
00108         /*... do some further init work here */
00109 
00110 
00111         /* Send OK to parent process */
00112         daemon_retval_send(0);
00113 
00114         daemon_log(LOG_INFO, "Sucessfully started");
00115 
00116 
00117         /* Prepare for select() on the signal fd */
00118         FD_ZERO(&fds);
00119         FD_SET(fd = daemon_signal_fd(), &fds);
00120         
00121         while (!quit) {
00122             fd_set fds2 = fds;
00123 
00124             /* Wait for an incoming signal */
00125             if (select(FD_SETSIZE, &fds2, 0, 0, 0) < 0) {
00126 
00127                 /* If we've been interrupted by an incoming signal, continue */
00128                 if (errno == EINTR)
00129                     continue;
00130                 
00131                 daemon_log(LOG_ERR, "select(): %s", strerror(errno));
00132                 break;
00133             }
00134 
00135             /* Check if a signal has been recieved */
00136             if (FD_ISSET(fd, &fds)) {
00137                 int sig;
00138 
00139                 /* Get signal */
00140                 if ((sig = daemon_signal_next()) <= 0) {
00141                     daemon_log(LOG_ERR, "daemon_signal_next() failed.");
00142                     break;
00143                 }
00144 
00145                 /* Dispatch signal */
00146                 switch (sig) {
00147 
00148                     case SIGINT:
00149                     case SIGQUIT:
00150                         daemon_log(LOG_WARNING, "Got SIGINT or SIGQUIT");
00151                         quit = 1;
00152                         break;
00153 
00154                     case SIGHUP:
00155                         daemon_log(LOG_INFO, "Got a HUP");
00156                         daemon_exec("/", NULL, "/bin/ls", "ls", (char*) NULL);
00157                         break;
00158 
00159                 }
00160             }
00161         }
00162 
00163         /* Do a cleanup */
00164 finish:
00165         daemon_log(LOG_INFO, "Exiting...");
00166 
00167         daemon_signal_done();
00168         daemon_pid_file_remove();
00169         
00170         return 0;
00171     }
00172 }

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