From e8147843fc072c5056d99b6c162216d82f1eedc7 Mon Sep 17 00:00:00 2001
From: wm4 <wm4@nowhere>
Date: Fri, 7 Jun 2019 17:09:22 +0200
Subject: demux: really disable cache for sub-demuxers

It seems the so called demuxer cache wasn't really disabled for
sub-demuxers (timeline stuff). This was relatively harmless, since the
actual packet data was shared anyway via refcounting. But with the
addition of a mmap cache backend, this may change a lot.

So strictly disable any caching for sub-demuxers. This assumes that
users of sub-demuxers (only demux_timeline.c by now?) strictly use
demux_read_any_packet(), since demux_read_packet_async() will require
some minor read-ahead if a low level packet read returned a packet for a
different stream.

This requires some awkward messing with this fucking heap of trash. The
thing that is really wrong here is that the demuxer API mixes different
concepts, and sub-demuxers get the same API as decoders, and use the
cache code.
---
 demux/demux.c | 15 ++++++++++-----
 demux/demux.h |  1 +
 2 files changed, 11 insertions(+), 5 deletions(-)

(limited to 'demux')

diff --git a/demux/demux.c b/demux/demux.c
index 775d95b187..882e8e605f 100644
--- a/demux/demux.c
+++ b/demux/demux.c
@@ -2923,21 +2923,26 @@ static struct demuxer *open_given_type(struct mpv_global *global,
                 seekable = 1;
         }
         in->seekable_cache = seekable == 1;
+        struct demuxer *sub = NULL;
         if (!(params && params->disable_timeline)) {
             struct timeline *tl = timeline_load(global, log, demuxer);
             if (tl) {
                 struct demuxer_params params2 = {0};
                 params2.timeline = tl;
-                struct demuxer *sub =
+                params2.is_top_level = params && params->is_top_level;
+                sub =
                     open_given_type(global, log, &demuxer_desc_timeline,
                                     demuxer->stream, &params2, DEMUX_CHECK_FORCE);
-                if (sub) {
-                    demuxer = sub;
-                } else {
+                if (!sub)
                     timeline_destroy(tl);
-                }
             }
         }
+        if (!(params && params->is_top_level) || sub) {
+            in->seekable_cache = false;
+            in->min_secs = 0;
+            in->max_bytes = 1;
+        }
+        demuxer = sub ? sub : demuxer;
         // Let this demuxer free demuxer->stream. Timeline sub-demuxers can
         // share a stream, and in these cases the demux_timeline instance
         // should own the stream, as it frees the sub demuxers first.
diff --git a/demux/demux.h b/demux/demux.h
index da315adebb..63897c342d 100644
--- a/demux/demux.h
+++ b/demux/demux.h
@@ -158,6 +158,7 @@ typedef struct demux_attachment
 } demux_attachment_t;
 
 struct demuxer_params {
+    bool is_top_level; // if true, it's not a sub-demuxer (enables cache etc.)
     char *force_format;
     int matroska_num_wanted_uids;
     struct matroska_segment_uid *matroska_wanted_uids;
-- 
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