demux_mkv, stream: attempt to improve behavior in unseekable streams

stream_skip() semantics were kind of bad, especially after the recent
change to the stream code. Forward stream_skip() calls could still
trigger a seek and fail, even if it was supposed to actually skip data.
(Maybe the idea that stream_skip() should try to seek is worthless in
the first place.)

Rename it to stream_seek_skip() (takes absolute position now because I
think that's better), and make it always skip if the stream is marked as
forward.

While we're at it, make EOF detection more robust. I guess s->eof
shouldn't exist at all, since it's valid only "sometimes". It should be
removed... but not today. A 1-byte stream_read_peek() call is good to
get the s->eof flag set to a correct value.

1 files changed, 1 insertions, 1 deletions

diff --git a/stream/stream_libarchive.c b/stream/stream_libarchive.c
index ab8fda0f34..e3109dfb0a 100644
--- a/stream/stream_libarchive.c
+++ b/stream/stream_libarchive.c
@@ -84,7 +84,7 @@ static int64_t skip_cb(struct archive *arch, void *priv, int64_t request)
     if (!volume_seek(vol))
         return -1;
     int64_t old = stream_tell(vol->src);
-    stream_skip(vol->src, request);
+    stream_seek_skip(vol->src, old + request);
     return stream_tell(vol->src) - old;
 }