#21 add daemon

BaseCommon/Daemon.cpp

@@ -0,0 +1,132 @@
+/*
+ *   Copyright (c) 2022 by Geoffrey Merck F4FXL / KC3FRA
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+/*
+ * Losely based on https://github.com/jirihnidek/daemon/blob/master/src/daemon.c
+ */
+
+#include <unistd.h>
+#include <cstdlib>
+#include <csignal>
+#include <sys/stat.h>
+#include <cstdio>
+#include <cstring>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+
+#include "Daemon.h"
+#include "Log.h"
+
+int CDaemon::m_pid_fd = -1;
+std::string CDaemon::m_pidFileName("");
+
+DAEMONIZE_RESULT CDaemon::daemonize(const std::string& pidFile)
+{
+	pid_t pid = 0;
+	int fd;
+
+	/* Fork off the parent process */
+	pid = fork();
+
+	/* An error occurred */
+	if (pid < 0) {
+		return DR_FAILURE;
+	}
+
+	/* Success: Let the parent terminate */
+	if (pid > 0) {
+		return DR_PARENT;
+	}
+
+	/* On success: The child process becomes session leader */
+	if (setsid() < 0) {
+        return DR_FAILURE;
+	}
+
+	/* Ignore signal sent from child to parent process */
+	signal(SIGCHLD, SIG_IGN);
+
+	/* Fork off for the second time*/
+	pid = fork();
+
+	/* An error occurred */
+	if (pid < 0) {
+		return DR_FAILURE;
+	}
+
+	/* Success: Let the parent terminate */
+	if (pid > 0) {
+		return DR_PARENT;
+	}
+
+	/* Set new file permissions */
+	umask(0);
+
+	/* Change the working directory to the root directory */
+	/* or another appropriated directory */
+	chdir("/");
+
+	/* Close all open file descriptors */
+	for (fd = sysconf(_SC_OPEN_MAX); fd > 0; fd--) {
+		close(fd);
+	}
+
+	/* Reopen stdin (fd = 0), stdout (fd = 1), stderr (fd = 2) */
+	stdin = fopen("/dev/null", "r");
+	stdout = fopen("/dev/null", "w+");
+	stderr = fopen("/dev/null", "w+");
+
+	/* Try to write PID of daemon to lockfile */
+	if (!pidFile.empty())
+	{
+        CLog::logInfo("pidfile");
+		
+		m_pid_fd = open(pidFile.c_str(), O_RDWR|O_CREAT, 0640);
+		if (m_pid_fd < 0) {
+			/* Can't open lockfile */
+			return DR_PIDFILE_FAILED;
+		}
+		if (lockf(m_pid_fd, F_TLOCK, 0) < 0) {
+			/* Can't lock file */
+			return DR_PIDFILE_FAILED;
+		}
+
+        m_pidFileName.assign(pidFile);
+
+		/* Get current PID */
+        char str[256];
+		sprintf(str, "%d\n", getpid());
+		/* Write PID to lockfile */
+		write(m_pid_fd, str, strlen(str));
+	}
+
+    return DR_CHILD;
+}
+
+void CDaemon::finalize()
+{
+    if(m_pid_fd != -1) {
+        lockf(m_pid_fd, F_ULOCK, 0);
+		close(m_pid_fd);
+    }
+
+    if(!m_pidFileName.empty()) {
+        unlink(m_pidFileName.c_str());
+    }
+}

BaseCommon/Daemon.h

@@ -0,0 +1,38 @@
+/*
+ *   Copyright (c) 2022 by Geoffrey Merck F4FXL / KC3FRA
+ *
+ *   This program is free software; you can redistribute it and/or modify
+ *   it under the terms of the GNU General Public License as published by
+ *   the Free Software Foundation; either version 2 of the License, or
+ *   (at your option) any later version.
+ *
+ *   This program is distributed in the hope that it will be useful,
+ *   but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *   GNU General Public License for more details.
+ *
+ *   You should have received a copy of the GNU General Public License
+ *   along with this program; if not, write to the Free Software
+ *   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <string>
+
+enum DAEMONIZE_RESULT
+{
+    DR_PARENT,
+    DR_CHILD,
+    DR_FAILURE,
+    DR_PIDFILE_FAILED
+};
+
+class CDaemon
+{
+public:
+    static DAEMONIZE_RESULT daemonize(const std::string& pidFile);
+    static void finalize();
+
+private:
+    static int m_pid_fd;
+    static std::string m_pidFileName;
+};