--- a/syslog_kernel.c	Tue May 30 12:05:42 2006 +0200
+++ b/syslog_kernel.c	Tue May 30 12:34:25 2006 +0200
@@ -188,10 +188,109 @@
 	program_handler(SIGHUP, reconfig_handler);
 }
 
+static void check_pid()
+{
+	int fh;
+	char name[MAX_STRING];
+	char buffer[MAX_STRING];
+	int buffer_size;
+	int pid, res;
+
+	assert (get_config(PID_FILE, name, MAX_STRING) > 0);
+
+	fh = open(name, O_RDONLY);
+	if (fh == -1)
+	{
+		/* If the file doesn't exist, it's normal. */
+		return;
+	}
+
+	buffer_size = MAX_STRING;
+	buffer_size = read(fh, buffer, buffer_size);
+	if (buffer_size <= 0)
+	{
+		fprintf(stderr, "Error reading the pid file: %s\n",
+				strerror(errno));
+		close(fh);
+		return;
+	}
+	buffer[buffer_size] = '\0';
+
+	pid = atoi(buffer);
+
+	if (pid > 0)
+	{
+		res = kill(pid, SIGHUP);
+		if (res == 0)
+		{
+			/* The syslog_kernel seems to be running and restared */
+			fprintf(stderr,"syslog_kernel running. Restarted.\n");
+			close(fh);
+			exit(0);
+		} else if (res == -1)
+		{
+			fprintf(stderr,"An old pid file has been found. "
+				"Ignoring it.\n");
+		}
+	}
+
+	close(fh);
+}
+
+static void write_pid()
+{
+	int fh;
+	char name[MAX_STRING];
+	char buffer[MAX_STRING];
+	int buffer_size;
+	int res;
+
+	assert (get_config(PID_FILE, name, MAX_STRING) > 0);
+
+	fh = open(name, O_WRONLY | O_TRUNC | O_CREAT, 0644);
+	if (fh == -1)
+	{
+		fprintf(stderr, "Error opening the pid file for write: %s\n",
+				strerror(errno));
+		return;
+	}
+
+	buffer_size = snprintf(buffer, MAX_STRING, "%i", getpid());
+	if (buffer_size < MAX_STRING)
+	{
+		buffer[buffer_size++] = '\n';
+	}
+
+	res = write(fh, buffer, buffer_size);
+	if (buffer_size <= 0)
+		fprintf(stderr, "Error writting the pid file: %s\n",
+				strerror(errno));
+
+	close(fh);
+}
+
+static void remove_pid()
+{
+	int res;
+	char name[MAX_STRING];
+
+	assert (get_config(PID_FILE, name, MAX_STRING) > 0);
+	res = unlink(name);
+
+	if (res == -1)
+		fprintf(stderr, "Error unlinking the pid file: %s\n",
+				strerror(errno));
+}
+
+
+
 int main(int argn, char *argv[])
 {
 	int res;
 
+	check_pid();
+	write_pid();
+
 	install_signal_handlers();
 
 	do
@@ -228,4 +327,6 @@
 		wait_childs_die();
 	}
 	while(reconfig == true);
+
+	remove_pid();
 }