int main(void)
{
hs_monitor *monitor = NULL;
hs_poll_source sources[2];
int r;
r = hs_monitor_new(NULL, 0, &monitor);
if (r < 0)
goto cleanup;
/* Enumerate devices and start listening to OS notifications. The list is refreshed and the
callback is called only when hs_monitor_refresh() is called. Use hs_monitor_get_poll_handle()
to get a pollable descriptor and integrate it to your event loop. */
r = hs_monitor_start(monitor);
if (r < 0)
goto cleanup;
/* hs_monitor_list() uses a cached device list in the monitor object, which is only updated
when you call hs_monitor_start() and hs_monitor_refresh(). */
r = hs_monitor_list(monitor, device_callback, NULL);
if (r < 0)
goto cleanup;
/* Add the waitable descriptor provided by the monitor to the descriptor set, it will
become ready (POLLIN) when there are pending events. */
sources[0].desc = hs_monitor_get_poll_handle(monitor);
/* We also want to poll the terminal/console input buffer, to exit on key presses. */
#ifdef _WIN32
sources[1].desc = GetStdHandle(STD_INPUT_HANDLE);
#else
sources[1].desc = STDIN_FILENO;
#endif
printf("Monitoring devices (press RETURN to end):\n");
do {
/* This function is non-blocking, if there are no pending events it does nothing and
returns immediately. It calls the callback function for each notification (add or
remove) and updates the device list accessed by hs_monitor_list(). */
r = hs_monitor_refresh(monitor, device_callback, NULL);
if (r < 0)
goto cleanup;
/* This function returns the number of ready sources, 0 if it times out or a negative
error code. You can simply check each source's ready field after each call. */
r = hs_poll(sources, 2, -1);
} while (r > 0 && !sources[1].ready);
if (sources[1].ready) {
#ifndef _WIN32
/* Clear the terminal input buffer, just to avoid the extra return/characters from
showing up when this program exits. This has nothing to do with libhs. */
tcflush(STDIN_FILENO, TCIFLUSH);
#endif
r = 0;
}
cleanup:
hs_monitor_free(monitor);
return -r;
}
int main(void)
{
hs_monitor *monitor = NULL;
/* This is a quick way to clear the descriptor set, you are free to use `set->count = 0;`
or hs_descriptor_set_clear(). */
hs_descriptor_set set = {0};
int r;
r = hs_monitor_new(&monitor);
if (r < 0)
goto cleanup;
printf("Current devices:\n");
/* hs_monitor_new() goes through the device tree and makes an initial device list, so we
don't need hs_monitor_refresh() yet. But if you don't call hs_monitor_list()
immediately, you need to use hs_monitor_refresh() before hs_monitor_list(). */
r = hs_monitor_list(monitor, device_callback, NULL);
if (r < 0)
goto cleanup;
/* Register our event callback, this is called from within hs_monitor_refresh() whenever
something interesting happens (i.e. a device is added or removed). */
r = hs_monitor_register_callback(monitor, device_callback, NULL);
if (r < 0)
goto cleanup;
printf("\n");
/* Add the waitable descriptor provided by the monitor to the descriptor set, it will
become ready when there are pending events. */
hs_descriptor_set_add(&set, hs_monitor_get_descriptor(monitor), 1);
/* We also want to poll the terminal/console input buffer. */
#ifdef _WIN32
hs_descriptor_set_add(&set, GetStdHandle(STD_INPUT_HANDLE), 2);
#else
hs_descriptor_set_add(&set, STDIN_FILENO, 2);
#endif
printf("Monitoring devices (press RETURN to end):\n");
do {
/* This function is non-blocking, if there are no pending events it does nothing and
returns immediately. */
r = hs_monitor_refresh(monitor);
if (r < 0)
goto cleanup;
/* This function returns the value associated with the ready descriptor, in this case
1 when there are monitor events and 2 when RETURN is pressed. */
r = hs_poll(&set, -1);
} while (r == 1);
if (r == 2) {
#ifndef _WIN32
/* Clear the terminal input buffer, just to avoid the extra return/characters from
* showing up when this program exits. This has nothing to do with libhs. */
tcflush(STDIN_FILENO, TCIFLUSH);
#endif
r = 0;
}
cleanup:
hs_monitor_free(monitor);
return -r;
}
