Make sure we don't get stuck when prebuf is too high

If prebuf is greater than tlength minus minreq we might end up waiting
for the buffer to fill up further however without ever asking for more
data from the client since less minreq bytes might be missing.

This fixes bug #440

2 files changed, 29 insertions, 32 deletions

diff --git a/src/pulsecore/memblockq.c b/src/pulsecore/memblockq.c
index d12d13a8..77f9efc9 100644
--- a/src/pulsecore/memblockq.c
+++ b/src/pulsecore/memblockq.c
@@ -90,8 +90,8 @@ pa_memblockq* pa_memblockq_new(
 
     pa_memblockq_set_maxlength(bq, maxlength);
     pa_memblockq_set_tlength(bq, tlength);
-    pa_memblockq_set_prebuf(bq, prebuf);
     pa_memblockq_set_minreq(bq, minreq);
+    pa_memblockq_set_prebuf(bq, prebuf);
     pa_memblockq_set_maxrewind(bq, maxrewind);
 
     pa_log_debug("memblockq sanitized: maxlength=%lu, tlength=%lu, base=%lu, prebuf=%lu, minreq=%lu maxrewind=%lu",
@@ -784,16 +784,13 @@ void pa_memblockq_set_maxlength(pa_memblockq *bq, size_t maxlength) {
 
     if (bq->tlength > bq->maxlength)
         pa_memblockq_set_tlength(bq, bq->maxlength);
-
-    if (bq->prebuf > bq->maxlength)
-        pa_memblockq_set_prebuf(bq, bq->maxlength);
 }
 
 void pa_memblockq_set_tlength(pa_memblockq *bq, size_t tlength) {
     size_t old_tlength;
     pa_assert(bq);
 
-    if (tlength <= 0)
+    if (tlength <= 0 || tlength == (size_t) -1)
         tlength = bq->maxlength;
 
     old_tlength = bq->tlength;
@@ -802,49 +799,46 @@ void pa_memblockq_set_tlength(pa_memblockq *bq, size_t tlength) {
     if (bq->tlength > bq->maxlength)
         bq->tlength = bq->maxlength;
 
-    if (bq->prebuf > bq->tlength)
-        pa_memblockq_set_prebuf(bq, bq->tlength);
-
     if (bq->minreq > bq->tlength)
         pa_memblockq_set_minreq(bq, bq->tlength);
 
+    if (bq->prebuf > bq->tlength+bq->base-bq->minreq)
+        pa_memblockq_set_prebuf(bq, bq->tlength+bq->base-bq->minreq);
+
     bq->missing += (int64_t) bq->tlength - (int64_t) old_tlength;
 }
 
+void pa_memblockq_set_minreq(pa_memblockq *bq, size_t minreq) {
+    pa_assert(bq);
+
+    bq->minreq = (minreq/bq->base)*bq->base;
+
+    if (bq->minreq > bq->tlength)
+        bq->minreq = bq->tlength;
+
+    if (bq->minreq < bq->base)
+        bq->minreq = bq->base;
+
+    if (bq->prebuf > bq->tlength+bq->base-bq->minreq)
+        pa_memblockq_set_prebuf(bq, bq->tlength+bq->base-bq->minreq);
+}
+
 void pa_memblockq_set_prebuf(pa_memblockq *bq, size_t prebuf) {
     pa_assert(bq);
 
     if (prebuf == (size_t) -1)
-        prebuf = bq->tlength;
+        prebuf = bq->tlength+bq->base-bq->minreq;
 
     bq->prebuf = ((prebuf+bq->base-1)/bq->base)*bq->base;
 
     if (prebuf > 0 && bq->prebuf < bq->base)
         bq->prebuf = bq->base;
 
-    if (bq->prebuf > bq->tlength)
-        bq->prebuf = bq->tlength;
+    if (bq->prebuf > bq->tlength+bq->base-bq->minreq)
+        bq->prebuf = bq->tlength+bq->base-bq->minreq;
 
     if (bq->prebuf <= 0 || pa_memblockq_get_length(bq) >= bq->prebuf)
         bq->in_prebuf = FALSE;
-
-    if (bq->minreq > bq->prebuf)
-        pa_memblockq_set_minreq(bq, bq->prebuf);
-}
-
-void pa_memblockq_set_minreq(pa_memblockq *bq, size_t minreq) {
-    pa_assert(bq);
-
-    bq->minreq = (minreq/bq->base)*bq->base;
-
-    if (bq->minreq > bq->tlength)
-        bq->minreq = bq->tlength;
-
-    if (bq->minreq > bq->prebuf)
-        bq->minreq = bq->prebuf;
-
-    if (bq->minreq < bq->base)
-        bq->minreq = bq->base;
 }
 
 void pa_memblockq_set_maxrewind(pa_memblockq *bq, size_t maxrewind) {
diff --git a/src/pulsecore/protocol-native.c b/src/pulsecore/protocol-native.c
index 59e5d80e..edcd5982 100644
--- a/src/pulsecore/protocol-native.c
+++ b/src/pulsecore/protocol-native.c
@@ -850,7 +850,7 @@ static int playback_stream_process_msg(pa_msgobject *o, int code, void*userdata,
 
 /* Called from main context */
 static void fix_playback_buffer_attr(playback_stream *s) {
-    size_t frame_size;
+    size_t frame_size, max_prebuf;
     pa_usec_t orig_tlength_usec, tlength_usec, orig_minreq_usec, minreq_usec, sink_usec;
 
     pa_assert(s);
@@ -976,8 +976,11 @@ static void fix_playback_buffer_attr(playback_stream *s) {
     if (s->buffer_attr.tlength <= s->buffer_attr.minreq)
         s->buffer_attr.tlength = s->buffer_attr.minreq*2 + (uint32_t) frame_size;
 
-    if (s->buffer_attr.prebuf == (uint32_t) -1 || s->buffer_attr.prebuf > s->buffer_attr.tlength)
-        s->buffer_attr.prebuf = s->buffer_attr.tlength;
+    max_prebuf = s->buffer_attr.tlength + (uint32_t)frame_size - s->buffer_attr.minreq;
+
+    if (s->buffer_attr.prebuf == (uint32_t) -1 ||
+        s->buffer_attr.prebuf > max_prebuf)
+        s->buffer_attr.prebuf = max_prebuf;
 }
 
 /* Called from main context */