Add pidfile support

3 files changed, 42 insertions, 2 deletions

diff --git a/src/config.c b/src/config.c
index a77c258..c28de7f 100644
--- a/src/config.c
+++ b/src/config.c
@@ -92,6 +92,8 @@ static void default_config(fastd_config *conf) {
 	conf->on_disestablish_dir = NULL;
 
 	conf->daemon = false;
+	conf->pid_file = NULL;
+
 	conf->machine_readable = false;
 	conf->generate_key = false;
 	conf->show_key = false;
@@ -374,6 +376,7 @@ static void count_peers(fastd_context *ctx, fastd_config *conf) {
 	OPTION(usage, "--help" OR "-h", "Shows this help text") \
 	OPTION(version, "--version" OR "-v", "Shows the fastd version") \
 	OPTION(option_daemon, "--daemon" OR "-d", "Runs fastd in the background") \
+	OPTION_ARG(option_pid_file, "--pid-file", "<filename>", "Writes fastd's PID to the specified file") \
 	OPTION_ARG(option_log_level, "--log-level", "error|warn|info|verbose|debug", "Sets the stderr log level; default is info, if no alternative log destination ist configured") \
 	OPTION_ARG(option_syslog_level, "--syslog-level", "error|warn|info|verbose|debug", "Sets the log level for syslog output; default is not to use syslog") \
 	OPTION_ARG(option_syslog_ident, "--syslog-ident", "<ident>", "Sets the syslog identification; default is 'fastd'") \
@@ -614,6 +617,12 @@ static void option_on_disestablish(fastd_context *ctx, fastd_config *conf, const
 static void option_daemon(fastd_context *ctx, fastd_config *conf) {
 	conf->daemon = true;
 }
+
+static void option_pid_file(fastd_context *ctx, fastd_config *conf, const char *arg) {
+	free(conf->pid_file);
+	conf->pid_file = strdup(arg);
+}
+
 static void option_generate_key(fastd_context *ctx, fastd_config *conf) {
 	conf->generate_key = true;
 	conf->show_key = false;
diff --git a/src/fastd.c b/src/fastd.c
index 9f92ddb..aa7ed44 100644
--- a/src/fastd.c
+++ b/src/fastd.c
@@ -667,6 +667,23 @@ static void close_fds(fastd_context *ctx) {
 	}
 }
 
+static void write_pid(fastd_context *ctx, pid_t pid) {
+	if (!ctx->conf->pid_file)
+		return;
+
+	int fd = open(ctx->conf->pid_file, O_WRONLY|O_CREAT, 0666);
+	if (fd < 0) {
+		pr_error_errno(ctx, "can't write PID file: open");
+		return;
+	}
+
+	if (dprintf(fd, "%i", pid) < 0)
+		pr_error_errno(ctx, "can't write PID file: dprintf");
+
+	if (close(fd) < 0)
+		pr_warn_errno(ctx, "close");
+}
+
 int main(int argc, char *argv[]) {
 	fastd_context ctx;
 	memset(&ctx, 0, sizeof(ctx));
@@ -704,8 +721,20 @@ int main(int argc, char *argv[]) {
 	init_peers(&ctx);
 
 	if (conf.daemon) {
-		if (daemon(1, 1) < 0)
-			exit_errno(&ctx, "daemon");
+		pid_t pid = fork();
+		if (pid < 0) {
+			exit_errno(&ctx, "fork");
+		}
+		else if (pid > 0) {
+			write_pid(&ctx, pid);
+			exit(0);
+		}
+
+		if (setsid() < 0)
+			pr_error_errno(&ctx, "setsid");
+	}
+	else {
+		write_pid(&ctx, getpid());
 	}
 
 	on_up(&ctx);
diff --git a/src/fastd.h b/src/fastd.h
index fbf86ab..2edfcfe 100644
--- a/src/fastd.h
+++ b/src/fastd.h
@@ -174,6 +174,8 @@ struct _fastd_config {
 	char *on_disestablish_dir;
 
 	bool daemon;
+	char *pid_file;
+
 	bool machine_readable;
 	bool generate_key;
 	bool show_key;