FIX(client): Infinite loop and log spam on ALSA input device disconne…

…ction

A user reported that sometimes the client log gets spammed with repeated messages such as:

<W>2025-01-10 10:24:10.638 ALSAAudioInput: No such device: No such device

The error corresponds to ENODEV (19), which we treat like any other.
Since it's unrecoverable, the code gets stuck in a full speed loop until the audio engine is stopped.

This commit:

1. Switches from snd_pcm_prepare() to snd_pcm_recover(), which is specifically designed to recover streams.
2. Breaks the loop if the error is not one of the only three recoverable (EINTR, EPIPE, ESTRPIPE). Example log:

<W>2025-01-14 06:16:44.494 ALSAAudioInput: File descriptor in bad state, breaking the loop...

Please note that also ALSAAudioOutput doesn't explicitly handle fatal errors in its loop, but it shouldn't run "infinitely" at full speed because poll-based.

src/mumble/ALSAAudio.cpp

@@ -305,7 +305,6 @@ ALSAAudioInput::~ALSAAudioInput() {
 
 void ALSAAudioInput::run() {
 	QMutexLocker qml(&qmALSA);
-	snd_pcm_sframes_t readblapp;
 
 	QByteArray device_name         = Global::get().s.qsALSAInput.toLatin1();
 	snd_pcm_hw_params_t *hw_params = nullptr;
@@ -379,21 +378,27 @@ void ALSAAudioInput::run() {
 		snd_pcm_status_dump(status, log);
 		snd_pcm_status_free(status);
 #endif
-		readblapp = snd_pcm_readi(capture_handle, inbuff.data(), static_cast< snd_pcm_uframes_t >(wantPeriod));
-		if (readblapp == -ESTRPIPE) {
-			qWarning("ALSAAudioInput: PCM suspended, trying to resume");
-			while (bRunning && snd_pcm_resume(capture_handle) == -EAGAIN)
-				msleep(1000);
-			if ((err = snd_pcm_prepare(capture_handle)) < 0)
-				qWarning("ALSAAudioInput: %s: %s", snd_strerror(static_cast< int >(readblapp)), snd_strerror(err));
-		} else if (readblapp == -EPIPE) {
-			err = snd_pcm_prepare(capture_handle);
-			qWarning("ALSAAudioInput: %s: %s", snd_strerror(static_cast< int >(readblapp)), snd_strerror(err));
-		} else if (readblapp < 0) {
-			err = snd_pcm_prepare(capture_handle);
-			qWarning("ALSAAudioInput: %s: %s", snd_strerror(static_cast< int >(readblapp)), snd_strerror(err));
-		} else if (wantPeriod == static_cast< unsigned int >(readblapp)) {
-			addMic(inbuff.data(), static_cast< unsigned int >(readblapp));
+		const snd_pcm_sframes_t ret = snd_pcm_readi(capture_handle, inbuff.data(), wantPeriod);
+		if (ret >= 0) {
+			if (static_cast< snd_pcm_uframes_t >(ret) == wantPeriod) {
+				addMic(inbuff.data(), static_cast< unsigned int >(ret));
+			}
+		} else {
+			err = static_cast< decltype(err) >(ret);
+			switch (err) {
+				case -EINTR:
+				case -EPIPE:
+				case -ESTRPIPE:
+					qWarning("ALSAAudioInput: %s, attempting to recover the stream...", snd_strerror(err));
+					while (bRunning && snd_pcm_recover(capture_handle, err, 1) == -EAGAIN) {
+						msleep(1000);
+					}
+
+					break;
+				default:
+					qWarning("ALSAAudioInput: %s, breaking the loop...", snd_strerror(err));
+					bRunning = false;
+			}
 		}
 	}