xdg-desktop-portal: fix icon validation

Validation requires bubblewrap, but the current build system does not enforce it being present.

Additionally, the validation itself needs to have thumbnailer Nix store paths available in sandbox. Let’s add a patch from Flatpak and introduce a test verifying it still works.

This was probably broken since https://github.com/NixOS/nixpkgs/commit/c3b07a052fadf19bfa6b7a26e1c12125da4ef71d

pkgs/development/libraries/xdg-desktop-portal/default.nix

@@ -3,9 +3,9 @@
 , autoreconfHook
 , dbus
 , fetchFromGitHub
-, fetchpatch
 , flatpak
 , fuse3
+, bubblewrap
 , systemdMinimal
 , geoclue2
 , glib
@@ -20,12 +20,12 @@
 , python3
 , pkg-config
 , stdenv
-, substituteAll
+, runCommand
 , wrapGAppsHook
 , enableGeoLocation ? true
 }:
 
-stdenv.mkDerivation rec {
+stdenv.mkDerivation (finalAttrs: {
   pname = "xdg-desktop-portal";
   version = "1.15.0";
 
@@ -33,11 +33,21 @@ stdenv.mkDerivation rec {
 
   src = fetchFromGitHub {
     owner = "flatpak";
-    repo = pname;
-    rev = version;
+    repo = "xdg-desktop-portal";
+    rev = finalAttrs.version;
     sha256 = "sha256-Kw3zJeGwPfw1fDo8HsgYmrpgCk/PUvWZPRloKJNAJVc=";
   };
 
+  patches = [
+    # The icon validator copied from Flatpak needs to access the gdk-pixbuf loaders
+    # in the Nix store and cannot bind FHS paths since those are not available on NixOS.
+    (runCommand "icon-validator.patch" { } ''
+      # Flatpak uses a different path
+      substitute "${flatpak.icon-validator-patch}" "$out" \
+        --replace "/icon-validator/validate-icon.c" "/src/validate-icon.c"
+    '')
+  ];
+
   nativeBuildInputs = [
     autoreconfHook
     libxml2
@@ -50,6 +60,7 @@ stdenv.mkDerivation rec {
     dbus
     flatpak
     fuse3
+    bubblewrap
     systemdMinimal # libsystemd
     glib
     gsettings-desktop-schemas
@@ -83,6 +94,11 @@ stdenv.mkDerivation rec {
   passthru = {
     tests = {
       installedTests = nixosTests.installed-tests.xdg-desktop-portal;
+
+      validate-icon = runCommand "test-icon-validation" { } ''
+        ${finalAttrs.finalPackage}/libexec/xdg-desktop-portal-validate-icon --sandbox 512 512 ${../../../applications/audio/zynaddsubfx/ZynLogo.svg} > "$out"
+        grep format=svg "$out"
+      '';
     };
   };
 
@@ -92,4 +108,4 @@ stdenv.mkDerivation rec {
     maintainers = with maintainers; [ jtojnar ];
     platforms = platforms.linux;
   };
-}
+})