Slightly less hacky --compiler for callCabal2nix#6
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ElvishJerricco wants to merge 1 commit intoobsidiansystems:ios-refresh-2from
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Slightly less hacky --compiler for callCabal2nix#6ElvishJerricco wants to merge 1 commit intoobsidiansystems:ios-refresh-2from
ElvishJerricco wants to merge 1 commit intoobsidiansystems:ios-refresh-2from
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Oh strange. The GHCJS build was necessary just to do the |
Ericson2314
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Jan 4, 2023
Without this change it segfaults when trying to play any media: $ jellyfinmediaplayer Warning: Ignoring XDG_SESSION_TYPE=wayland on Gnome. Use QT_QPA_PLATFORM=wayland to run on Wayland anyway. libpng warning: iCCP: known incorrect sRGB profile Logging to /home/bf/.local/share/jellyfinmediaplayer/logs/jellyfinmediaplayer.log Cannot load libcuda.so.1 Segmentation fault (core dumped) The backtrace shows pipewire being at fault: $ coredumpctl debug [...] Program terminated with signal SIGSEGV, Segmentation fault. #0 0x00007f711428c9bb in core_event_demarshal_remove_id () from /nix/store/nhffrd7f15dhfbkwzgayq7hhzmdvdy19-pipewire-0.3.63-lib/lib/pipewire-0.3/libpipewire-module-protocol-native.so [Current thread is 1 (Thread 0x7f6ffdc87640 (LWP 1360949))] (gdb) bt #0 0x00007f711428c9bb in core_event_demarshal_remove_id () from /nix/store/nhffrd7f15dhfbkwzgayq7hhzmdvdy19-pipewire-0.3.63-lib/lib/pipewire-0.3/libpipewire-module-protocol-native.so #1 0x00007f711428886c in process_remote () from /nix/store/nhffrd7f15dhfbkwzgayq7hhzmdvdy19-pipewire-0.3.63-lib/lib/pipewire-0.3/libpipewire-module-protocol-native.so #2 0x00007f7114288e68 in on_remote_data () from /nix/store/nhffrd7f15dhfbkwzgayq7hhzmdvdy19-pipewire-0.3.63-lib/lib/pipewire-0.3/libpipewire-module-protocol-native.so #3 0x00007f7114310efe in loop_iterate () from /nix/store/nhffrd7f15dhfbkwzgayq7hhzmdvdy19-pipewire-0.3.63-lib/lib/spa-0.2/support/libspa-support.so #4 0x00007f71266fe7f2 in do_loop () from /nix/store/nhffrd7f15dhfbkwzgayq7hhzmdvdy19-pipewire-0.3.63-lib/lib/libpipewire-0.3.so.0 #5 0x00007f7128b08e86 in start_thread () from /nix/store/ayfr5l52xkqqjn3n4h9jfacgnchz1z7s-glibc-2.35-224/lib/libc.so.6 #6 0x00007f7128b8fce0 in clone3 () from /nix/store/ayfr5l52xkqqjn3n4h9jfacgnchz1z7s-glibc-2.35-224/lib/libc.so.6 (gdb) Standalone mpv doesn't segfault (when directly playing the underlying media files). I don't know why. Fixes: b97cda7 ("mpv-unwrapped: 0.34.1 -> 0.35.0") Fixes NixOS#205141 Ref jellyfin/jellyfin-desktop#341 (cherry picked from commit 3c528bc)
Ericson2314
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Feb 6, 2026
On my systems there is a path in the fonts list that looks like
/nix/store/<hash>-<font>.ttf. The previous code assumed that every font path
contains at least one more slash which isn't the case here.
The code matched on the / after the $out path of the derivation:
/nix/store/<hash>-<name>/share/X11/fonts/...
^
That slash only exists if the font lives in a subdirectory, which
isn't strictly required. In my case I've a few font files that are
located at /nix/store/<hash>-<name>.ttf and are assembled into a
folder as symlinks. (See example below)
Any attempt at calling realpath(3) on them (potentially recursively)
will result in the single file entry in the store being returned.
Whenever that font is being loaded flatpak segfaulted like so:
```
(gdb) bt
#0 0x00005583b3673763 in get_nix_closure ()
#1 0x00005583b3673711 in get_nix_closure ()
#2 0x00005583b36737dc in add_nix_store_symlink_targets ()
#3 0x00005583b36749a8 in add_font_path_args ()
#4 0x00005583b367b3f4 in flatpak_run_app ()
#5 0x00005583b35e4f08 in flatpak_builtin_run ()
#6 0x00005583b35a5970 in main ()
(gdb) x/5i $rip
=> 0x5583b3673763 <get_nix_closure+307>: movb $0x0,(%rax)
0x5583b3673766 <get_nix_closure+310>: call 0x5583b35a46a0 <g_hash_table_add@plt>
0x5583b367376b <get_nix_closure+315>: jmp 0x5583b3673699 <get_nix_closure+105>
0x5583b3673770 <get_nix_closure+320>: xor %edi,%edi
0x5583b3673772 <get_nix_closure+322>: lea 0x30475(%rip),%rsi # 0x5583b36a3bee
(gdb) x/s $rsi
0x5583e92d2180: "/nix/store/<hash>-A.ttf"
(gdb) print $rax
$1 = 0
```
RAX pointing to 0 here corresponds to the pointer `p` in the source
code. So the code attempted to dereference a null pointer as no further
slash (the return value of strchr(3)) could be found.
The modification in this commit ensures that we check for `p != 0` so
we don't run into this situation again.
Adding the path to the closure will still be done, even if no further
slash can be found, as that still points to a valid store path.
----
Nix code for custom fonts:
```nix
let
files = [
./A.ttf
./B.ttf
];
in
runCommandNoCC "custom-fonts" {} ''
mkdir -p $out/share/fonts/truetype
cd $out/share/fonts/truetype
${ lib.concatStringsSep "\n" (map (file: "ln -s ${file} ${baseNameOf file}") files)}
''
```
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I noticed that
reflex-platformwill build dependencies with GHCJS that are supposed to be blocked byif impl(ghcjs)or the like.@Ericson2314 This triggers a mass rebuild. Any idea why? Although the
haskellSrc2nixderivations themselves should be changed, the expressions imported from there should be unchanged, so I wouldn't expect anything to need rebuilding. But it has to rebuild GHCJS, and a few of its dependencies.