Dusski: /* Viber on NixOS - Fix for Missing Libraries */ new section

2026-07-15T12:05:21Z

Viber on NixOS - Fix for Missing Libraries: new section

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== Viber on NixOS - Fix for Missing Libraries ==

== Fix for Missing Libraries (v27.3.0.2) ==

Viber fails to launch on NixOS due to two issues: missing runtime libraries and a broken <code>libxml2.so.2</code> symlink in the package.

=== Root Causes ===

==== 1. Missing system libraries ====
Viber's NixOS package doesn't include several required runtime libraries (<code>libxshmfence</code>, <code>libxcb-cursor</code>, <code>libxcb-util</code>, <code>pipewire</code>).

==== 2. Broken libxml2.so.2 symlink ====
The NixOS viber package creates a broken symlink:
<pre>opt/viber/lib/libxml2.so.2 -> /nix/store/.../libxml2-2.15.2/lib/libxml2.so</pre>

<code>libxml2-2.15.2</code> only ships <code>libxml2.so.16</code> (new ABI). Viber's bundled <code>libQt6WebEngineCore.so.6</code> requires <code>valuePush@@LIBXML2_2.4.30</code> from the old ABI, so it must be replaced with <code>libxml2_13</code> (2.13.x).

=== Working Configuration ===

Replace <code>pkgs.viber</code> in <code>environment.systemPackages</code> with:

<syntaxhighlight lang="nix">
(pkgs.buildFHSEnv {
name = "viber";
targetPkgs = pkgs: [
(pkgs.viber.overrideAttrs (old: {
postFixup = (old.postFixup or "") + ''
rm -f $out/opt/viber/lib/libxml2.so.2
ln -s ${pkgs.libxml2_13.out}/lib/libxml2.so.2 $out/opt/viber/lib/libxml2.so.2
'';
}))
pkgs.libxshmfence
pkgs.libxcb-cursor
pkgs.xcbutil
pkgs.pipewire
];
runScript = "viber";
extraInstallCommands = ''
mkdir -p $out/share/applications
cp ${pkgs.viber}/share/applications/viber.desktop $out/share/applications/
sed -i "s|Exec=.*|Exec=viber %u|" $out/share/applications/viber.desktop
sed -i "s|Path=.*|Path=/opt/viber/|" $out/share/applications/viber.desktop
'';
})
</syntaxhighlight>

=== Why each package is needed ===

{| class="wikitable"
! Package !! Provides !! Why needed
|-
| <code>pkgs.libxshmfence</code> || <code>libxshmfence.so.1</code> || Required by Viber's bundled Qt WebEngine
|-
| <code>pkgs.libxml2_13.out</code> || <code>libxml2.so.2</code> (old ABI) || Replaces broken symlink; Viber's Qt needs <code>valuePush@@LIBXML2_2.4.30</code>
|-
| <code>pkgs.libxcb-cursor</code> || <code>libxcb-cursor.so.0</code> || Required by Qt 6.5+ xcb platform plugin
|-
| <code>pkgs.xcbutil</code> || <code>libxcb-util.so.1</code> || Required by Qt's xcb platform plugin (<code>libQt6XcbQpa.so.6</code>)
|-
| <code>pkgs.pipewire</code> || <code>libpipewire-0.3.so</code> || Qt multimedia audio support
|}

=== Important Notes ===

* '''<code>libxml2_13.out</code> vs <code>libxml2_13</code>''': The bare attribute resolves to the <code>-bin</code> output which contains no <code>.so</code> files. Always use <code>.out</code>.
* '''<code>xcb-util</code> vs <code>xcbutil</code>''': Inside a NixOS config, use <code>pkgs.xcbutil</code> (no hyphen). <code>nix eval nixpkgs#xcb-util</code> works at the CLI but <code>pkgs.xcb-util</code> in a config file does not.
* '''Working directory''': <code>bwrap</code> (used by <code>buildFHSEnv</code>) does not map <code>/etc/nixos</code> inside the sandbox. Launch <code>viber</code> from <code>~</code>, not from <code>/etc/nixos</code>.

=== What Didn't Work ===

{| class="wikitable"
! Approach !! Why it failed
|-
| <code>programs.nix-ld.libraries</code> || Doesn't intercept library lookups for Viber's bundled libs
|-
| <code>steam-run viber</code> || Steam runtime doesn't include <code>libxshmfence</code> either
|-
| <code>writeShellScriptBin</code> with <code>LD_LIBRARY_PATH</code> || Leaks into Viber's own bundled libs causing <code>libxml2</code> version conflicts
|-
| <code>pkgs.libxml2_13</code> (bare) || Resolves to <code>-bin</code> output — symlink points nowhere
|-
| <code>pkgs.xcb-util</code> || Attribute doesn't exist in pkgs set; correct name is <code>pkgs.xcbutil</code>
|} [[User:Dusski|Dusski]] ([[User talk:Dusski|talk]]) 12:05, 15 July 2026 (UTC)

Talk:Viber - Revision history

Dusski: /* Viber on NixOS - Fix for Missing Libraries */ new section