Add support for AVIRT

Leverage the new AVIRT driver for a more secure, more dynamically
configurable loopback sound driver.

To use, replace the file smixer-4a-default.json with
smixer-4a-avirt.json, at /usr/libexec/agl/smixer/etc.
The snd-avirt drivers are installed in AGL by default as of 6.99.2.

The existing snd-aloop configuration is not broken by this change.

Change-Id: I827636656c109a7393ad77997e05069a2462ea46
Signed-off-by: Mark Farrugia <mark.farrugia@fiberdyne.com.au>

1 files changed, 16 insertions, 7 deletions

diff --git a/plugins/alsa/alsa-api-streams.c b/plugins/alsa/alsa-api-streams.c
index c1fb749..edf506e 100644
--- a/plugins/alsa/alsa-api-streams.c
+++ b/plugins/alsa/alsa-api-streams.c
@@ -19,6 +19,7 @@
 #define _GNU_SOURCE  // needed for vasprintf
 
 #include "alsa-softmixer.h"
+#include <avirt/avirt.h>
 
 #include <string.h>
 #include <stdbool.h>
@@ -231,6 +232,7 @@ STATIC int CreateOneStream(SoftMixerT *mixer, const char * uid, AlsaStreamAudioT
     char *volName = NULL;
     int pauseNumid = 0;
     int volNumid = 0;
+    int device, subdev;
 
 	AFB_API_DEBUG(mixer->api,
 				"NEW STREAM stream %s %s, source %s, sink %s, mute %d",
@@ -238,12 +240,20 @@ STATIC int CreateOneStream(SoftMixerT *mixer, const char * uid, AlsaStreamAudioT
 
     loopDev = ApiLoopFindSubdev(mixer, stream->uid, stream->source, &loop);
     if (loopDev) {
+        if (loop->avirt) {
+            device = loopDev->index;
+            subdev = 0;
+        } else { // loop->avirt == false
+            device = loop->capture;
+            subdev = loopDev->index;
+        }
+
         // create a valid PCM reference and try to open it.
         captureDev->devpath = NULL;
         captureDev->cardid = NULL;
         captureDev->cardidx = loop->sndcard->cid.cardidx;
-        captureDev->device = loop->capture;
-        captureDev->subdev = loopDev->index;
+        captureDev->device = device;
+        captureDev->subdev = subdev;
         captureDev->pcmplug_params = NULL;
         captureCard = loop->sndcard;
 
@@ -476,11 +486,10 @@ STATIC int CreateOneStream(SoftMixerT *mixer, const char * uid, AlsaStreamAudioT
     }
 
     if (loop) {
-		if (asprintf((char**) &stream->source, "hw:%d,%d,%d", captureDev->cardidx, loop->playback, capturePcm->cid.subdev) == -1) {
-			SOFTMIXER_NOMEM(mixer->api);
-			goto OnErrorExit;
-		}
-
+        int device = (loop->avirt) ? captureDev->device
+                                   : loop->playback;
+        if (asprintf((char**) &stream->source, "hw:%d,%d,%d", captureDev->cardidx, device, capturePcm->cid.subdev) == -1)
+            goto OnErrorExit;
     } else {
 		if (asprintf((char**) &stream->source, "hw:%d,%d,%d", captureDev->cardidx, captureDev->device, captureDev->subdev) == -1) {
 			SOFTMIXER_NOMEM(mixer->api);