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Michel-FK
183
daemon.c
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183
daemon.c
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/*
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Copyright (C) 2021 Michel Stempin <michel.stempin@funkey-project.com>
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This file is part of the FunKey S GPIO keyboard daemon.
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This is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The software is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, write to the Free
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Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
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02111-1307 USA.
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*/
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/**
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* @file daemon.c
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* This file contains the daemon function for the FunKey S GPIO daemon
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*/
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#include <stdio.h>
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#include <signal.h>
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#include <syslog.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <fcntl.h>
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#include <string.h>
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#include <unistd.h>
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#include <sys/stat.h>
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#include "daemon.h"
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/* Process ID file descriptor */
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static int pid_fd;
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/* Process ID lock file name */
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static char *pid_lock_file;
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/* Signal handler */
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void signal_handler(int sig)
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{
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switch(sig){
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case SIGHUP:
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syslog(LOG_WARNING, "Received SIGHUP.");
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break;
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case SIGINT:
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case SIGTERM:
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syslog(LOG_INFO, "Exiting.");
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close(pid_fd);
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unlink(pid_lock_file);
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exit(EXIT_SUCCESS);
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break;
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default:
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syslog(LOG_WARNING, "Unhandled signal %s", strsignal(sig));
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}
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}
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/* Get the pid from the pid lock file and terminate the daemon */
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void kill_daemon(char *pidfile)
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{
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int n;
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pid_t pid;
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char str[10];
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pid_fd = open(pidfile, O_RDONLY, 0600);
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if (pid_fd < 0) {
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perror(pidfile);
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} else {
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if (read(pid_fd, str, 10) > 0) {
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pid = strtol(str, NULL, 0);
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if (pid) {
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printf("terminating %d\n", pid);
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n = kill(pid, SIGTERM);
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if (n < 0) {
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perror("kill");
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}
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}
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}
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close(pid_fd);
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}
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}
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/* Turn the running process into a daemon */
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void daemonize(char *rundir, char *pidfile)
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{
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int pid, i;
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char str[10];
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struct sigaction sa;
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sigset_t ss;
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/* Check if parent process is already init */
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if (getppid() == 1) {
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/* Don't need to do it twice */
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return;
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}
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/* Fork off the parent process */
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pid = fork();
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if (pid < 0) {
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perror("first fork");
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exit(EXIT_FAILURE);
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} else if (pid > 0) {
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/* Success. terminate the parent */
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exit(EXIT_SUCCESS);
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}
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/* On success: the child process becomes the session leader */
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if (setsid() < 0) {
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perror("set SID");
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exit(EXIT_FAILURE);
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}
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/* Block these signals */
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sigemptyset(&ss);
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sigaddset(&ss, SIGCHLD);
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sigaddset(&ss, SIGTSTP);
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sigaddset(&ss, SIGTTOU);
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sigaddset(&ss, SIGTTIN);
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sigprocmask(SIG_BLOCK, &ss, NULL);
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/* Handle these signals */
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sa.sa_handler = signal_handler;
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sigemptyset(&sa.sa_mask);
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sa.sa_flags = 0;
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sigaction(SIGHUP, &sa, NULL);
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sigaction(SIGTERM, &sa, NULL);
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sigaction(SIGINT, &sa, NULL);
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/* Fork off for a second time to ensure that we get rid of the session
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* leading process
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*/
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pid = fork();
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if (pid < 0) {
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perror("second fork");
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exit(EXIT_FAILURE);
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} else if (pid > 0) {
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/* Success. terminate the parent */
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exit(EXIT_SUCCESS);
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}
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/* Set new file permissions */
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umask(0);
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/* Change the working directory to the root directory or another
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* appropriated directory
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*/
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if (chdir(rundir) < 0) {
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perror(rundir);
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}
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/* Close all opened file descriptors */
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for (i = sysconf(_SC_OPEN_MAX); i >= 0; i--) {
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close(i);
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}
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/* Make sure there is only one daemon running at a time using a lock file */
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pid_lock_file = pidfile;
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pid_fd = open(pidfile, O_RDWR | O_CREAT, 0600);
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if (pid_fd < 0) {
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syslog(LOG_INFO, "Could not open lock file %s. Exiting.", pidfile);
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exit(EXIT_FAILURE);
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}
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if (lockf(pid_fd, F_TLOCK, 0) < 0) {
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syslog(LOG_INFO, "Could not lock lock file %s. Exiting.", pidfile);
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unlink(pidfile);
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exit(EXIT_FAILURE);
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}
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sprintf(str, "%d\n", getpid());
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if (write(pid_fd, str, strlen(str)) < 0) {
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perror(pidfile);
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}
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syslog(LOG_INFO, "Daemon running.");
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}
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