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authorwm4 <wm4@nowhere>2019-11-14 12:59:14 +0100
committerwm4 <wm4@nowhere>2019-11-14 12:59:14 +0100
commitac7f67b3f23a63e463fb881d960bc8f31a230292 (patch)
tree5d40b4c6a9df371dde1317b2a758b50f7df68439
parentdcc3c2eb3877f9876cc218b1e5f1187b81036c49 (diff)
downloadmpv-ac7f67b3f23a63e463fb881d960bc8f31a230292.tar.bz2
mpv-ac7f67b3f23a63e463fb881d960bc8f31a230292.tar.xz
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.
-rw-r--r--demux/demux_mkv.c4
-rw-r--r--demux/demux_playlist.c2
-rw-r--r--demux/ebml.c5
-rw-r--r--stream/stream.c14
-rw-r--r--stream/stream.h4
-rw-r--r--stream/stream_libarchive.c2
6 files changed, 16 insertions, 15 deletions
diff --git a/demux/demux_mkv.c b/demux/demux_mkv.c
index bd36edb784..4c5f376137 100644
--- a/demux/demux_mkv.c
+++ b/demux/demux_mkv.c
@@ -1954,7 +1954,7 @@ static int read_mkv_segment_header(demuxer_t *demuxer, int64_t *segment_end)
if (demuxer->params)
num_skip = demuxer->params->matroska_wanted_segment;
- while (!s->eof) {
+ while (stream_read_peek(s, &(char){0}, 1)) {
if (ebml_read_id(s) != MATROSKA_ID_SEGMENT) {
MP_VERBOSE(demuxer, "segment not found\n");
return 0;
@@ -2580,7 +2580,7 @@ static int read_block(demuxer_t *demuxer, int64_t end, struct block_info *block)
exit:
if (res <= 0)
free_block(block);
- stream_seek(s, endpos);
+ stream_seek_skip(s, endpos);
return res;
}
diff --git a/demux/demux_playlist.c b/demux/demux_playlist.c
index a7650b2b69..b51edad86c 100644
--- a/demux/demux_playlist.c
+++ b/demux/demux_playlist.c
@@ -99,7 +99,7 @@ static int read_characters(stream_t *s, uint8_t *dst, int dstsize, int utf16)
if (len > dstsize)
return -1; // line too long
memcpy(dst, buf, len);
- stream_skip(s, len);
+ stream_seek_skip(s, len);
return len;
}
}
diff --git a/demux/ebml.c b/demux/ebml.c
index 44fa0c0793..143a5fe57b 100644
--- a/demux/ebml.c
+++ b/demux/ebml.c
@@ -180,14 +180,14 @@ int ebml_read_skip(struct mp_log *log, int64_t end, stream_t *s)
if (len >= INT64_MAX - pos2 || (end > 0 && pos2 + len > end))
goto invalid;
- if (!stream_skip(s, len))
+ if (!stream_seek_skip(s, pos2 + len))
goto invalid;
return 0;
invalid:
mp_err(log, "Invalid EBML length at position %"PRId64"\n", pos);
- stream_seek(s, pos);
+ stream_seek_skip(s, pos);
return 1;
}
@@ -198,6 +198,7 @@ int ebml_resync_cluster(struct mp_log *log, stream_t *s)
{
int64_t pos = stream_tell(s);
uint32_t last_4_bytes = 0;
+ stream_read_peek(s, &(char){0}, 1);
if (!s->eof) {
mp_err(log, "Corrupt file detected. "
"Trying to resync starting from position %"PRId64"...\n", pos);
diff --git a/stream/stream.c b/stream/stream.c
index 7fd6700cdd..271e268a1c 100644
--- a/stream/stream.c
+++ b/stream/stream.c
@@ -692,13 +692,13 @@ bool stream_seek(stream_t *s, int64_t pos)
return stream_seek_unbuffered(s, pos);
}
-bool stream_skip(stream_t *s, int64_t len)
+// Like stream_seek(), but strictly prefer skipping data instead of failing, if
+// it's a forward-seek.
+bool stream_seek_skip(stream_t *s, int64_t pos)
{
- if (!stream_seek(s, stream_tell(s) + len))
- return false;
- // Make sure s->eof is set correctly, even if a seek happened.
- stream_read_more(s, 1);
- return true;
+ return !s->seekable && pos > stream_tell(s)
+ ? stream_skip_read(s, pos - stream_tell(s))
+ : stream_seek(s, pos);
}
int stream_control(stream_t *s, int cmd, void *arg)
@@ -732,7 +732,7 @@ int stream_skip_bom(struct stream *s)
bstr data = {buf, len};
for (int n = 0; n < 3; n++) {
if (bstr_startswith0(data, bom[n])) {
- stream_skip(s, strlen(bom[n]));
+ stream_seek_skip(s, stream_tell(s) + strlen(bom[n]));
return n;
}
}
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);
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;
}