winmm_output_plugin: fail if wrong device specified instead of using fallback.

Silently choosing default is misleading and can cause hours of investigation.
It's better to fail immediately telling user what is wrong with config.

NEWS

@@ -20,6 +20,7 @@ ver 0.17 (2011/??/??)
   - raop: new output plugin
   - shout: add possibility to set url
   - roar: new output plugin for RoarAudio
+  - winmm: fail if wrong device specified instead of using default device
 * playlist:
   - allow references to songs outside the music directory
 * state_file: add option "restore_paused"

src/output/winmm_output_plugin.c

@@ -74,33 +74,45 @@ winmm_output_test_default_device(void)
 	return waveOutGetNumDevs() > 0;
 }
 
-static UINT
-get_device_id(const char *device_name)
+static bool
+get_device_id(const char *device_name, UINT *device_id, GError **error_r)
 {
 	/* if device is not specified use wave mapper */
-	if (device_name == NULL)
-		return WAVE_MAPPER;
+	if (device_name == NULL) {
+		*device_id = WAVE_MAPPER;
+		return true;
+	}
+
+	UINT numdevs = waveOutGetNumDevs();
 
 	/* check for device id */
 	char *endptr;
 	UINT id = strtoul(device_name, &endptr, 0);
-	if (endptr > device_name && *endptr == 0)
-		return id;
+	if (endptr > device_name && *endptr == 0) {
+		if (id >= numdevs)
+			goto fail;
+		*device_id = id;
+		return true;
+	}
 
 	/* check for device name */
-	for (UINT i = 0; i < waveOutGetNumDevs(); i++) {
+	for (UINT i = 0; i < numdevs; i++) {
 		WAVEOUTCAPS caps;
 		MMRESULT result = waveOutGetDevCaps(i, &caps, sizeof(caps));
 		if (result != MMSYSERR_NOERROR)
 			continue;
 		/* szPname is only 32 chars long, so it is often truncated.
 		   Use partial match to work around this. */
-		if (strstr(device_name, caps.szPname) == device_name)
-			return i;
+		if (strstr(device_name, caps.szPname) == device_name) {
+			*device_id = i;
+			return true;
+		}
 	}
 
-	/* fallback to wave mapper */
-	return WAVE_MAPPER;
+fail:
+	g_set_error(error_r, winmm_output_quark(), 0,
+		    "device \"%s\" is not found", device_name);
+	return false;
 }
 
 static struct audio_output *
@@ -113,7 +125,12 @@ winmm_output_init(const struct config_param *param, GError **error_r)
 	}
 
 	const char *device = config_get_block_string(param, "device", NULL);
-	wo->device_id = get_device_id(device);
+	if (!get_device_id(device, &wo->device_id, error_r)) {
+		ao_base_finish(&wo->base);
+		g_free(wo);
+		return NULL;
+	}
+
 	return &wo->base;
 }