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authorTanu Kaskinen <tanu.kaskinen@digia.com>2011-02-24 16:16:43 +0200
committerColin Guthrie <cguthrie@mandriva.org>2011-02-26 10:40:06 +0000
commit6bd34156b130c07b130de10111a12ef6dab18b52 (patch)
tree08d635f07c2165c669eed2bfcd1310babed74e38 /src/pulsecore
parentb3644c1bcd5f5d73fd2dc7b898e66b11ca3ad588 (diff)
virtual-sink: Fix a crash when moving the sink to a new master right after setup.
If the virtual sink is moved to a new master right after it has been created, then the virtual sink input's memblockq can be rewound to a negative read index. The data written prior to the move starts from index zero, so after the rewind there's a bit of silence. If the memblockq doesn't have a silence memchunk set, then pa_memblockq_peek() will return zero in such case, and the returned memchunk's memblock pointer will be NULL. That scenario wasn't taken into account in the implementation of sink_input_pop_cb. Setting a silence memchunk for the memblockq solves this problem, because pa_memblock_peek() will now return a valid memblock if the read index happens to point to a hole in the memblockq. I believe this isn't the best possible solution, though. It doesn't really make sense to rewind the sink input's memblockq beyond index 0 in the first place, because now when the stream starts to play to the new master sink, there's some unnecessary silence before the actual data starts. This is a small problem, though, and I don't grok the rewinding system well enough to know how to fix this issue properly. I went through all files that call pa_memblockq_peek() to see if there are more similar bugs. play-memblockq.c was the only one that looked to me like it might be broken in the same way. I didn't try reproducing the bug with play-memblockq.c, though, so I just added a FIXME comment there.
Diffstat (limited to 'src/pulsecore')
-rw-r--r--src/pulsecore/play-memblockq.c6
1 files changed, 6 insertions, 0 deletions
diff --git a/src/pulsecore/play-memblockq.c b/src/pulsecore/play-memblockq.c
index 0d6da3ee..f075a5bf 100644
--- a/src/pulsecore/play-memblockq.c
+++ b/src/pulsecore/play-memblockq.c
@@ -135,6 +135,12 @@ static int sink_input_pop_cb(pa_sink_input *i, size_t nbytes, pa_memchunk *chunk
return -1;
}
+ /* FIXME: u->memblockq doesn't have a silence memchunk set, so
+ * pa_memblockq_peek() will return 0 without returning any memblock if the
+ * read index points to a hole. If the memblockq is rewound beyond index 0,
+ * then there will be a hole. */
+ pa_assert(chunk->memblock);
+
chunk->length = PA_MIN(chunk->length, nbytes);
pa_memblockq_drop(u->memblockq, chunk->length);