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/**
* Based on alsactl/monitor.c (by Takashi Iwai <tiwai@suse.de>) from alsa-utils
* http://git.alsa-project.org/?p=alsa-utils.git;a=blob_plain;f=alsactl/monitor.c;hb=HEAD
*
* Inspired by kbdd
*/
#include <stdio.h>
#include <alsa/asoundlib.h>
#include <dbus/dbus.h>
int notify(DBusConnection *conn)
{
DBusMessage *msg;
dbus_uint32_t serial = 0;
msg = dbus_message_new_signal("/com/ch1p/Object", "com.ch1p.avm", "valueChanged");
if (NULL == msg) {
fprintf(stderr, "DBus: Message Null\n");
return 1;
}
if (!dbus_connection_send(conn, msg, &serial)) {
fprintf(stderr, "DBus send: Out Of Memory!\n");
return 1;
}
dbus_connection_flush(conn);
dbus_message_unref(msg);
return 0;
}
int open_ctl(const char *name, snd_ctl_t **ctlp)
{
snd_ctl_t *ctl;
int err;
err = snd_ctl_open(&ctl, name, SND_CTL_READONLY);
if (err < 0) {
fprintf(stderr, "Cannot open ctl %s\n", name);
return err;
}
err = snd_ctl_subscribe_events(ctl, 1);
if (err < 0) {
fprintf(stderr, "Cannot open subscribe events to ctl %s\n", name);
snd_ctl_close(ctl);
return err;
}
*ctlp = ctl;
return 0;
}
int check_event(snd_ctl_t *ctl, DBusConnection *conn)
{
snd_ctl_event_t *event;
unsigned int mask;
int err;
snd_ctl_event_alloca(&event);
err = snd_ctl_read(ctl, event);
if (err < 0)
return err;
if (snd_ctl_event_get_type(event) != SND_CTL_EVENT_ELEM)
return 0;
mask = snd_ctl_event_elem_get_mask(event);
if (!(mask & SND_CTL_EVENT_MASK_VALUE))
return 0;
notify(conn);
return 0;
}
#define MAX_CARDS 256
int monitor(const char *name, DBusConnection *conn) {
snd_ctl_t *ctl;
int err = 0;
err = open_ctl(name, &ctl);
if (err < 0)
goto error;
while (1) {
struct pollfd fd;
snd_ctl_poll_descriptors(ctl, &fd, 1);
err = poll(&fd, 1, -1);
if (err <= 0) {
err = 0;
break;
}
unsigned short revents;
snd_ctl_poll_descriptors_revents(ctl, &fd, 1,
&revents);
if (revents & POLLIN)
check_event(ctl, conn);
}
error:
snd_ctl_close(ctl);
return err;
}
void usage()
{
fprintf(stderr,
"Usage:\n"
" alsa-volume-monitor <card name>\n\n"
"Example:\n"
" alsa-volume-monitor hw:0\n");
exit(1);
}
int main(int argc, char *argv[])
{
if (argc < 2)
usage();
DBusConnection *connection;
DBusError err;
int ret;
dbus_error_init(&err);
connection = dbus_bus_get(DBUS_BUS_SESSION, &err);
if (dbus_error_is_set(&err)) {
fprintf(stderr, "DBus Connection Error (%s)\n", err.message);
dbus_error_free(&err);
}
if (!connection) {
return 1;
}
ret = dbus_bus_request_name(connection, "com.ch1p.avm",
DBUS_NAME_FLAG_REPLACE_EXISTING , &err);
if (dbus_error_is_set(&err)) {
fprintf(stderr, "DBus Name Error (%s)\n", err.message);
dbus_error_free(&err);
}
monitor(argv[1], connection);
return 0;
}
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