cue files not playable when in remote DB mode

[vale-max]

Bug report

Describe the bug

If MPD is configured to use a remote DB via proxy plugin, playing a track from single flac file using a cue sheet fails with:
ERROR: Failed to decode "/media/Music/Flac_rips/Erykah Badu/Baduizm/Erykah Badu-Baduizm.cue/track0001"; Failed to open "/media/Music/Flac_rips/Erykah Badu/Baduizm/Erykah Badu-Baduizm.cue/track0001": Not a directory

The error is the same if the files are local, nfs or smb

The directory contains:

ls -l /media/Music/Flac_rips/Erykah\ Badu/Baduizm/
total 336912
-rwxr-xr-x 1 root root      1466 12 nov  2008 'Erykah Badu-Baduizm.cue'
-rwxr-xr-x 1 root root 344991752 12 nov  2008 'Erykah Badu-Baduizm.flac'

If the database is local, the same track is played correctly

Expected Behavior

Play the track from the cue file even if DB is remote

Actual Behavior

play fails with error above

Version

Server:mpd --version
Music Player Daemon 0.24.6 (0.24.6)

Client:mpd --version
Music Player Daemon 0.24.4 (0.24.4)

Configuration

music_directory		"/media/Music"
playlist_directory		"/var/lib/mpd/playlists"
state_file			"/var/lib/mpd/state"
sticker_file                   "/var/lib/mpd/sticker.sql"
user				"mpd"
bind_to_address			"any"
database {
       plugin "proxy"
       host "nas.lan"
       port "6600"
}
input {
        plugin "curl"
}
decoder {
        plugin                  "hybrid_dsd"
        enabled                 "no"
}
decoder {
        plugin        "wildmidi"
        enabled       "no"
        #config_file "/etc/timidity/timidity.cfg"
}
audio_output {
        type            "alsa"
        name            "Bluetooth Out"
        device          "bluealsa"      # optional
        mixer_type      "software"      # optional
}
audio_output {
        type            "alsa"
        name            "HiFiBerry"
        device          "hw:CARD=sndrpihifiberry,DEV=0"      # optional
        mixer_type      "software"      # optional
}
filesystem_charset		"UTF-8"

[vale-max]

I tried to dig a bit, hope this can help.
I tested again with a cue/flac without spaces in the middle, just to avoid other possible issues...
The file I tried to play is:
Flac_rips/Genesis/Trespass/Trespass.cue/track0001
When in local database mode mpd tries to open the correct flac file:

Thread 5 "decoder" hit Catchpoint 1 (call to syscall openat), 0x00007ffff0db69ee in ?? () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) bt
#0  0x00007ffff0db69ee in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#1  0x00007ffff0dab668 in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#2  0x00007ffff0dab6ad in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#3  0x00007ffff0e1f7fd in open64 () from /lib/x86_64-linux-gnu/libc.so.6
#4  0x000055555560c93c in open (__path=0x7fffcc000c40 "/var/lib/mpd/music/Flac_rips/Genesis/Trespass/Trespass.flac", __oflag=<optimized out>)
    at /usr/include/x86_64-linux-gnu/bits/fcntl2.h:61
#5  FileDescriptor::Open (this=this@entry=0x7fffe1735f0c, 
    pathname=pathname@entry=0x7fffcc000c40 "/var/lib/mpd/music/Flac_rips/Genesis/Trespass/Trespass.flac", flags=flags@entry=0, mode=mode@entry=438)
    at ../src/io/FileDescriptor.cxx:80
#6  0x00005555556c25f3 in OpenReadOnly (path=<optimized out>, path@entry=0x7fffcc000c40 "/var/lib/mpd/music/Flac_rips/Genesis/Trespass/Trespass.flac", 
    flags=flags@entry=0) at ../src/io/Open.cxx:22
#7  0x0000555555625bf9 in OpenUringInputStream (path=0x7fffcc000c40 "/var/lib/mpd/music/Flac_rips/Genesis/Trespass/Trespass.flac", mutex=...)
    at ../src/input/plugins/UringInputPlugin.cxx:181
#8  0x000055555562241c in OpenLocalInputStream (path=path@entry=..., mutex=...) at ../src/input/LocalOpen.cxx:32
#9  0x00005555555c4921 in DecoderBridge::OpenLocal (this=this@entry=0x7fffe1736190, path_fs=path_fs@entry=..., 
    uri_utf8=uri_utf8@entry=0x7fffd8000fa0 "/var/lib/mpd/music/Flac_rips/Genesis/Trespass/Trespass.flac") at ../src/decoder/Bridge.cxx:57
#10 0x00005555555c2432 in decoder_run_file (bridge=..., uri_utf8=0x7fffd8000fa0 "/var/lib/mpd/music/Flac_rips/Genesis/Trespass/Trespass.flac", path_fs=...)
    at ../src/decoder/Thread.cxx:462
#11 DecoderUnlockedRunUri (bridge=..., real_uri=0x7fffd8000fa0 "/var/lib/mpd/music/Flac_rips/Genesis/Trespass/Trespass.flac", path_fs=...)
    at ../src/decoder/Thread.cxx:502
#12 decoder_run_song (dc=..., song=..., uri=0x7fffd8000fa0 "/var/lib/mpd/music/Flac_rips/Genesis/Trespass/Trespass.flac", path_fs=...)
    at ../src/decoder/Thread.cxx:576
#13 decoder_run (dc=...) at ../src/decoder/Thread.cxx:621
#14 0x00005555555c3126 in DecoderControl::RunThread (this=0x7fffe1f37160) at ../src/decoder/Thread.cxx:646
#15 0x0000555555612851 in BoundMethod<void () noexcept>::operator()() const (this=<optimized out>) at ../src/util/BindMethod.hxx:52
#16 Thread::Run (this=<optimized out>) at ../src/thread/Thread.cxx:53
#17 Thread::ThreadProc (ctx=<optimized out>) at ../src/thread/Thread.cxx:82
#18 0x00007ffff0daeb7b in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#19 0x00007ffff0e2c7f8 in ?? () from /lib/x86_64-linux-gnu/libc.so.6

In remote database mode instead it really tries to open a non-existing file:

Thread 6 "decoder" hit Catchpoint 1 (call to syscall openat), 0x00007ffff0db69ee in ?? () from /lib/x86_64-linux-gnu/libc.so.6
(gdb) bt
#0  0x00007ffff0db69ee in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#1  0x00007ffff0dab668 in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#2  0x00007ffff0dab6ad in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#3  0x00007ffff0e1f7fd in open64 () from /lib/x86_64-linux-gnu/libc.so.6
#4  0x000055555560c93c in open (__path=0x7fffcc000c50 "/var/lib/mpd/music/Flac_rips/Genesis/Trespass/Trespass.cue/track0001", __oflag=<optimized out>)
    at /usr/include/x86_64-linux-gnu/bits/fcntl2.h:61
#5  FileDescriptor::Open (this=this@entry=0x7fffe1735f0c, 
    pathname=pathname@entry=0x7fffcc000c50 "/var/lib/mpd/music/Flac_rips/Genesis/Trespass/Trespass.cue/track0001", flags=flags@entry=0, mode=mode@entry=438)
    at ../src/io/FileDescriptor.cxx:80
#6  0x00005555556c25f3 in OpenReadOnly (path=<optimized out>, 
    path@entry=0x7fffcc000c50 "/var/lib/mpd/music/Flac_rips/Genesis/Trespass/Trespass.cue/track0001", flags=flags@entry=0) at ../src/io/Open.cxx:22
#7  0x0000555555625bf9 in OpenUringInputStream (path=0x7fffcc000c50 "/var/lib/mpd/music/Flac_rips/Genesis/Trespass/Trespass.cue/track0001", mutex=...)
    at ../src/input/plugins/UringInputPlugin.cxx:181
#8  0x000055555562241c in OpenLocalInputStream (path=path@entry=..., mutex=...) at ../src/input/LocalOpen.cxx:32
#9  0x00005555555c4921 in DecoderBridge::OpenLocal (this=this@entry=0x7fffe1736190, path_fs=path_fs@entry=..., 
    uri_utf8=uri_utf8@entry=0x7fffd8000fb0 "/var/lib/mpd/music/Flac_rips/Genesis/Trespass/Trespass.cue/track0001") at ../src/decoder/Bridge.cxx:57
#10 0x00005555555c2432 in decoder_run_file (bridge=..., uri_utf8=0x7fffd8000fb0 "/var/lib/mpd/music/Flac_rips/Genesis/Trespass/Trespass.cue/track0001", 
    path_fs=...) at ../src/decoder/Thread.cxx:462
#11 DecoderUnlockedRunUri (bridge=..., real_uri=0x7fffd8000fb0 "/var/lib/mpd/music/Flac_rips/Genesis/Trespass/Trespass.cue/track0001", path_fs=...)
    at ../src/decoder/Thread.cxx:502
#12 decoder_run_song (dc=..., song=..., uri=0x7fffd8000fb0 "/var/lib/mpd/music/Flac_rips/Genesis/Trespass/Trespass.cue/track0001", path_fs=...)
    at ../src/decoder/Thread.cxx:576
#13 decoder_run (dc=...) at ../src/decoder/Thread.cxx:621
#14 0x00005555555c3126 in DecoderControl::RunThread (this=0x7fffe1f37160) at ../src/decoder/Thread.cxx:646
#15 0x0000555555612851 in BoundMethod<void () noexcept>::operator()() const (this=<optimized out>) at ../src/util/BindMethod.hxx:52
#16 Thread::Run (this=<optimized out>) at ../src/thread/Thread.cxx:53
#17 Thread::ThreadProc (ctx=<optimized out>) at ../src/thread/Thread.cxx:82
#18 0x00007ffff0daeb7b in ?? () from /lib/x86_64-linux-gnu/libc.so.6
#19 0x00007ffff0e2c7f8 in ?? () from /lib/x86_64-linux-gnu/libc.so.6

Probably the problem is in how the entry is received from the remote DB server, this is the network capture of the request:

OK MPD 0.24.0
lsinfo "Flac_rips/Genesis/Trespass/Trespass.cue/track0001"
file: Flac_rips/Genesis/Trespass/Trespass.cue/track0001
Range: 0.000-427.266
Last-Modified: 2007-12-16T22:31:15Z
Added: 2026-05-03T11:06:50Z
Format: 44100:16:2
AlbumArtist: Genesis
Album: Trespass
Track: 01
Title: Looking for Someone
Artist: Genesis
Time: 427
duration: 427.266
OK

The entry in the original DB file seems ok to me:

directory: Trespass
mtime: 1309632834
begin: Flac_rips/Genesis/Trespass
directory: Trespass.cue
type: playlist
mtime: 1197847552
begin: Flac_rips/Genesis/Trespass/Trespass.cue
song_begin: track0001
Target: ../Trespass.flac
Range: 0-427266
AlbumArtist: Genesis
Album: Trespass
Track: 01
Title: Looking for Someone
Artist: Genesis
song_end

The target information apparently is not sent at all.

[vale-max]

@MaxKellermann I just notice PR #1780 which is for this same problem and dates back to 2023.

Is this something which is possible to fix, or should I give up the satellite setup and just use separate native databases for my MPDs ?