From e8147843fc072c5056d99b6c162216d82f1eedc7 Mon Sep 17 00:00:00 2001
From: wm4 <wm4@nowhere>
Date: Fri, 7 Jun 2019 17:09:22 +0200
Subject: [PATCH] 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 +
 player/loadfile.c |  5 ++++-
 3 files changed, 15 insertions(+), 6 deletions(-)

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;
diff --git a/player/loadfile.c b/player/loadfile.c
index c730d2e8f8..69cccb2c5c 100644
--- a/player/loadfile.c
+++ b/player/loadfile.c
@@ -724,7 +724,9 @@ int mp_add_external_file(struct MPContext *mpctx, char *filename,
     if (strncmp(disp_filename, "memory://", 9) == 0)
         disp_filename = "memory://"; // avoid noise
 
-    struct demuxer_params params = {0};
+    struct demuxer_params params = {
+        .is_top_level = true,
+    };
 
     switch (filter) {
     case STREAM_SUB:
@@ -968,6 +970,7 @@ static void *open_demux_thread(void *ctx)
         .force_format = mpctx->open_format,
         .stream_flags = mpctx->open_url_flags,
         .stream_record = true,
+        .is_top_level = true,
     };
     mpctx->open_res_demuxer =
         demux_open_url(mpctx->open_url, &p, mpctx->open_cancel, mpctx->global);