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livetrax/libs/ardouralsautil/request_device.c

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/*
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* 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.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
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*/
// NB generate man-page with
// help2man -N -n "alsa/ardour dbus device request tool" -o ardour-request-device.1 ./build/libs/ardouralsautil/ardour-request-device
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#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <getopt.h>
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#include <signal.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include <pthread.h>
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#include "ardouralsautil/reserve.h"
#ifndef ARD_PROG_NAME
#define ARD_PROG_NAME "alsa_request_device"
#endif
#ifndef ARD_APPL_NAME
#define ARD_APPL_NAME "ALSA User"
#endif
#ifndef VERSION
#define VERSION "v0.3"
#endif
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static int run = 1;
static int release_wait_for_signal = 0;
static pid_t parent_pid = 0;
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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 print_version (void) {
printf (ARD_PROG_NAME " " VERSION "\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 (EXIT_SUCCESS);
}
static void usage (void) {
printf (ARD_PROG_NAME " - DBus Audio Reservation Utility.\n");
printf ("Usage: " ARD_PROG_NAME " [ OPTIONS ] <Audio-Device-ID>\n");
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printf ("Options:\n\
-h, --help display this help and exit\n\
-p, --priority <int> reservation priority (default: int32_max)\n\
-P, --pid <int> process-id to watch (default 0: none)\n\
-n, --name <string> application name to use for registration\n\
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-V, --version print version information and exit\n\
-w, --releasewait wait for signal on yield-release\n\
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");
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.\n\
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\n\
" ARD_PROG_NAME " by default announces itself as \"" ARD_APPL_NAME "\"\n\
and uses the maximum possible priority for requesting the device.\n\
These settings can be overridden using the -n and -p options respectively.\n\
\n\
If a PID is given the tool will watch the process and if that is not running\n\
release the device and exit. Otherwise " ARD_PROG_NAME " runs until\n\
either stdin is closed, a SIGINT or SIGTERM is received or some other\n\
application requests the device with a higher priority.\n\
\n\
Without the -w option, " ARD_PROG_NAME " yields the device after 500ms to\n\
any higher-priority request. With the -w option this tool waits until it\n\
for SIGINT or SIGTERM - but at most 4 sec to acknowledge before releasing.\n\
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\n\
The audio-device-id is a string e.g. 'Audio1'\n\
\n\
Examples:\n\
" ARD_PROG_NAME " Audio0\n\
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\n");
printf ("Report bugs to Robin Gareus <robin@gareus.org>\n");
exit (EXIT_SUCCESS);
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}
static struct option const long_options[] =
{
{"help", no_argument, 0, 'h'},
{"name", required_argument, 0, 'n'},
{"pid", required_argument, 0, 'P'},
{"priority", required_argument, 0, 'p'},
{"version", no_argument, 0, 'V'},
{"releasewait", no_argument, 0, 'w'},
{NULL, 0, NULL, 0}
};
static int request_cb(rd_device *d, int forced) {
(void) d; // skip 'unused variable' compiler warning;
(void) forced; // skip 'unused variable' compiler warning;
fprintf(stdout, "Received higher priority request - releasing device.\n");
fflush(stdout);
if(!release_wait_for_signal) {
usleep (500000);
run = 0;
} else if (run) {
int timeout = 4000;
fprintf(stdout, "Waiting for acknowledge signal to release.\n");
while (release_wait_for_signal && run && --timeout) {
if (!stdin_available()) {
break;
}
if (parent_pid > 0 && kill (parent_pid, 0)) {
break;
}
usleep (1000);
}
run = 0;
}
return 1; // OK
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}
int main(int argc, char **argv) {
DBusConnection* dbus_connection = NULL;
rd_device * reserved_device = NULL;
DBusError error;
int ret, c;
int32_t priority = INT32_MAX;
char *name = strdup(ARD_APPL_NAME);
while ((c = getopt_long (argc, argv,
"h" /* help */
"n:" /* name */
"P:" /* pid */
"p:" /* priority */
"V" /* version */
"w", /* release wait for signal */
long_options, (int *) 0)) != EOF)
{
switch (c) {
case 'h':
free(name);
usage ();
break;
case 'n':
free(name);
name = strdup(optarg);
break;
case 'p':
priority = atoi (optarg);
if (priority < 0) priority = 0;
break;
case 'P':
parent_pid = atoi (optarg);
break;
case 'V':
free(name);
print_version ();
break;
case 'w':
release_wait_for_signal = 1;
break;
default:
free(name);
fprintf (stderr, "Error: unrecognized option. See --help for usage information.\n");
exit (EXIT_FAILURE);
break;
}
}
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if (optind + 1 != argc) {
fprintf (stderr, "Error: Missing parameter. See --help for usage information.\n");
free(name);
return EXIT_FAILURE;
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}
const char *device_name = argv[optind];
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if (parent_pid > 0 && kill (parent_pid, 0)) {
fprintf(stderr, "Given PID to watch is not running.\n");
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free(name);
return EXIT_FAILURE;
}
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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);
free(name);
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return EXIT_FAILURE;
}
if ((ret = rd_acquire (
&reserved_device,
dbus_connection,
device_name,
name,
priority,
request_cb,
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&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);
free(name);
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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 - releasing device.\n");
break;
}
if (parent_pid > 0 && kill (parent_pid, 0)) {
fprintf(stderr, "watched PID no longer exists - releasing device.\n");
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break;
}
}
rd_release (reserved_device);
fprintf(stdout, "Released audio-card '%s'\n", device_name);
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dbus_connection_unref(dbus_connection);
dbus_error_free(&error);
free(name);
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return EXIT_SUCCESS;
}