proper dbus device reservation

1 files changed, 139 insertions, 0 deletions

diff --git a/libs/ardouralsautil/request_device.c b/libs/ardouralsautil/request_device.c
new file mode 100644
index 0000000000..9e929c3cd0
--- /dev/null
+++ b/libs/ardouralsautil/request_device.c
@@ -0,0 +1,139 @@
+/*
+ * Copyright (C) 2014 Robin Gareus <robin@gareus.org>
+ *
+ * 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 <stdio.h>
+#include <stdlib.h>
+#include <unistd.h>
+#include <signal.h>
+#include <string.h>
+#include <fcntl.h>
+#include <errno.h>
+
+#include "ardouralsautil/reserve.h"
+
+static int run = 1;
+
+static void wearedone(int sig) {
+	(void) sig; // skip 'unused variable' compiler warning;
+	fprintf(stderr, "caught signal - shutting down.\n");
+	run=0;
+}
+
+static int stdin_available(void) {
+	errno = 0;
+	if (fcntl(STDIN_FILENO, F_GETFD) == 1) return 0;
+	return errno != EBADF;
+}
+
+static void usage(int status) {
+	printf ("ardour-request-device - DBus Audio Reservation Utility.\n");
+	printf ("Usage: ardour-request-device [ OPTIONS ] <Audio-Device-ID>\n");
+	printf ("Options:\n\
+      -h, --help                 display this help and exit\n\
+      -V, --version              print version information and exit\n\
+");
+
+	printf ("\n\
+This tool issues a dbus request to reserve an ALSA Audio-device.\n\
+If successful other users of the device (e.g. pulseaudio) will\n\
+release the device so that ardour can access it.\n\
+\n\
+ardour-request-device announces itself as \"Ardour ALSA Backend\" and uses the\n\
+maximum possible priority for requesting the device.\n\
+\n\
+The audio-device-id is a string e.g. 'Audio1'\n\
+\n\
+Examples:\n\
+ardour-request-device Audio0\n\
+\n");
+
+	printf ("Report bugs to Robin Gareus <robin@gareus.org>\n");
+	exit (status);
+}
+
+static void print_version(void) {
+	printf ("ardour-request-device 0.1\n\n");
+	printf (
+			"Copyright (C) 2014 Robin Gareus <robin@gareus.org>\n"
+			"This is free software; see the source for copying conditions.  There is NO\n"
+			"warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.\n\n"
+			);
+	exit (0);
+}
+
+int main(int argc, char **argv) {
+	DBusConnection* dbus_connection = NULL;
+	rd_device * reserved_device = NULL;
+	DBusError error;
+	int ret;
+
+	if (argc < 2 || argc > 2) {
+		usage(EXIT_FAILURE);
+	}
+	if (!strcmp(argv[1], "-V") || !strcmp(argv[1], "--version")) {
+		print_version();
+	}
+	if (!strcmp(argv[1], "-h") || !strcmp(argv[1], "--help")) {
+		usage(EXIT_SUCCESS);
+	}
+
+	const char *device_name = argv[1];
+
+	dbus_error_init(&error);
+
+	if (!(dbus_connection = dbus_bus_get (DBUS_BUS_SESSION, &error))) {
+		fprintf(stderr, "Failed to connect to session bus for device reservation: %s\n", error.message ? error.message : "unknown error.");
+		dbus_error_free(&error);
+		return EXIT_FAILURE;
+	}
+
+	if ((ret = rd_acquire (
+					&reserved_device,
+					dbus_connection,
+					device_name,
+					"Ardour ALSA Backend",
+					INT32_MAX,
+					NULL,
+					&error)) < 0)
+	{
+		fprintf(stderr, "Failed to acquire device: '%s'\n%s\n", device_name, (error.message ? error.message : strerror(-ret)));
+		dbus_error_free(&error);
+		dbus_connection_unref(dbus_connection);
+		return EXIT_FAILURE;
+	}
+
+	fprintf(stdout, "Acquired audio-card '%s'\n", device_name);
+	fprintf(stdout, "Press Ctrl+C or close stdin to release the device.\n");
+	fflush(stdout);
+
+	signal(SIGTERM, wearedone);
+	signal(SIGINT, wearedone);
+
+	while (run && dbus_connection_read_write_dispatch (dbus_connection, 200)) {
+		if (!stdin_available()) {
+			fprintf(stderr, "stdin closed - shutting down.\n");
+			break;
+		}
+	}
+
+	rd_release (reserved_device);
+	fprintf(stdout, "Released audio-card '%s'\n", device_name);
+	dbus_error_free(&error);
+	dbus_connection_unref(dbus_connection);
+	return EXIT_SUCCESS;
+}