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, 2 insertions, 2 deletions

diff --git a/stream/stream.h b/stream/stream.h
index 4a38d28109..d054e54914 100644
--- a/stream/stream.h
+++ b/stream/stream.h
@@ -121,7 +121,7 @@ typedef struct stream {
     void (*close)(struct stream *s);
 
     int64_t pos;
-    int eof;
+    int eof; // valid only after read calls that returned a short result
     int mode; //STREAM_READ or STREAM_WRITE
     void *priv; // used for DVD, TV, RTSP etc
     char *url;  // filename/url (possibly including protocol prefix)
@@ -194,7 +194,7 @@ inline static int64_t stream_tell(stream_t *s)
     return s->pos + s->buf_cur - s->buf_end;
 }
 
-bool stream_skip(stream_t *s, int64_t len);
+bool stream_seek_skip(stream_t *s, int64_t pos);
 bool stream_seek(stream_t *s, int64_t pos);
 int stream_read(stream_t *s, void *mem, int total);
 int stream_read_partial(stream_t *s, void *buf, int buf_size);