From: gineera <gineera@0f58301d-fd10-0410-b4af-bbb618454e57>
Date: Tue, 13 Aug 2013 20:37:04 +0000 (+0000)
Subject: Alsa: Fix handling of poll descriptors in PaAlsaStream_WaitForFrames().  Otherwise... 
X-Git-Tag: pa_stable_v19_20140130_r1919~13
X-Git-Url: https://andrewgundersen.net/repos?a=commitdiff_plain;h=b1a62661bfccdddeaa39d691722d83f8aab4eb9f;p=portaudio

Alsa: Fix handling of poll descriptors in PaAlsaStream_WaitForFrames().  Otherwise if capture signals before playback a duplex stream could poll the wrong descriptor, causing a loop (reported by Alexander Kartashov).
---

diff --git a/src/hostapi/alsa/pa_linux_alsa.c b/src/hostapi/alsa/pa_linux_alsa.c
index 7783d01..acd01cd 100644
--- a/src/hostapi/alsa/pa_linux_alsa.c
+++ b/src/hostapi/alsa/pa_linux_alsa.c
@@ -3770,7 +3770,8 @@ static PaError PaAlsaStream_WaitForFrames( PaAlsaStream *self, unsigned long *fr
         }
         if( pollPlayback )
         {
-            playbackPfds = self->pfds + (self->capture.pcm ? self->capture.nfds : 0);
+            /* self->pfds is in effect an array of fds; if necessary, index past the capture fds */
+            playbackPfds = self->pfds + (pollCapture ? self->capture.nfds : 0);
             PA_ENSURE( PaAlsaStreamComponent_BeginPolling( &self->playback, playbackPfds ) );
             totalFds += self->playback.nfds;
         }