treewide: rework Steam-shaped fhsenv building (#428815)

pkgs/build-support/build-fhsenv-bubblewrap/rootfs-builder/Cargo.lock

···
 # This file is automatically @generated by Cargo.
 # It is not intended for manual editing.
-version = 3
+version = 4
 
 [[package]]
 name = "anyhow"
-version = "1.0.91"
+version = "1.0.98"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c042108f3ed77fd83760a5fd79b53be043192bb3b9dba91d8c574c0ada7850c8"
+checksum = "e16d2d3311acee920a9eb8d33b8cbc1787ce4a264e85f964c2404b969bdcd487"
 
 [[package]]
 name = "goblin"
-version = "0.9.2"
+version = "0.10.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "53ab3f32d1d77146981dea5d6b1e8fe31eedcb7013e5e00d6ccd1259a4b4d923"
+checksum = "0e961b33649994dcf69303af6b3a332c1228549e604d455d61ec5d2ab5e68d3a"
 dependencies = [
  "log",
  "plain",
···
 
 [[package]]
 name = "itoa"
-version = "1.0.11"
+version = "1.0.15"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "49f1f14873335454500d59611f1cf4a4b0f786f9ac11f4312a78e4cf2566695b"
+checksum = "4a5f13b858c8d314ee3e8f639011f7ccefe71f97f96e50151fb991f267928e2c"
 
 [[package]]
 name = "log"
-version = "0.4.22"
+version = "0.4.27"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a7a70ba024b9dc04c27ea2f0c0548feb474ec5c54bba33a7f72f873a39d07b24"
+checksum = "13dc2df351e3202783a1fe0d44375f7295ffb4049267b0f3018346dc122a1d94"
 
 [[package]]
 name = "memchr"
-version = "2.7.4"
+version = "2.7.5"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "78ca9ab1a0babb1e7d5695e3530886289c18cf2f87ec19a575a0abdce112e3a3"
+checksum = "32a282da65faaf38286cf3be983213fcf1d2e2a58700e808f83f4ea9a4804bc0"
 
 [[package]]
 name = "plain"
···
 
 [[package]]
 name = "proc-macro2"
-version = "1.0.89"
+version = "1.0.95"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f139b0662de085916d1fb67d2b4169d1addddda1919e696f3252b740b629986e"
+checksum = "02b3e5e68a3a1a02aad3ec490a98007cbc13c37cbe84a3cd7b8e406d76e7f778"
 dependencies = [
  "unicode-ident",
 ]
 
 [[package]]
 name = "quote"
-version = "1.0.37"
+version = "1.0.40"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b5b9d34b8991d19d98081b46eacdd8eb58c6f2b201139f7c5f643cc155a633af"
+checksum = "1885c039570dc00dcb4ff087a89e185fd56bae234ddc7f056a945bf36467248d"
 dependencies = [
  "proc-macro2",
 ]
···
 
 [[package]]
 name = "ryu"
-version = "1.0.18"
+version = "1.0.20"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f3cb5ba0dc43242ce17de99c180e96db90b235b8a9fdc9543c96d2209116bd9f"
+checksum = "28d3b2b1366ec20994f1fd18c3c594f05c5dd4bc44d8bb0c1c632c8d6829481f"
 
 [[package]]
 name = "same-file"
···
 
 [[package]]
 name = "scroll"
-version = "0.12.0"
+version = "0.13.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "6ab8598aa408498679922eff7fa985c25d58a90771bd6be794434c5277eab1a6"
+checksum = "c1257cd4248b4132760d6524d6dda4e053bc648c9070b960929bf50cfb1e7add"
 dependencies = [
  "scroll_derive",
 ]
 
 [[package]]
 name = "scroll_derive"
-version = "0.12.0"
+version = "0.13.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7f81c2fde025af7e69b1d1420531c8a8811ca898919db177141a85313b1cb932"
+checksum = "22fc4f90c27b57691bbaf11d8ecc7cfbfe98a4da6dbe60226115d322aa80c06e"
 dependencies = [
  "proc-macro2",
  "quote",
···
 
 [[package]]
 name = "serde"
-version = "1.0.213"
+version = "1.0.219"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3ea7893ff5e2466df8d720bb615088341b295f849602c6956047f8f80f0e9bc1"
+checksum = "5f0e2c6ed6606019b4e29e69dbaba95b11854410e5347d525002456dbbb786b6"
 dependencies = [
  "serde_derive",
 ]
 
 [[package]]
 name = "serde_derive"
-version = "1.0.213"
+version = "1.0.219"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "7e85ad2009c50b58e87caa8cd6dac16bdf511bbfb7af6c33df902396aa480fa5"
+checksum = "5b0276cf7f2c73365f7157c8123c21cd9a50fbbd844757af28ca1f5925fc2a00"
 dependencies = [
  "proc-macro2",
  "quote",
···
 
 [[package]]
 name = "serde_json"
-version = "1.0.132"
+version = "1.0.141"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d726bfaff4b320266d395898905d0eba0345aae23b54aee3a737e260fd46db03"
+checksum = "30b9eff21ebe718216c6ec64e1d9ac57087aad11efc64e32002bce4a0d4c03d3"
 dependencies = [
  "itoa",
  "memchr",
···
 
 [[package]]
 name = "syn"
-version = "2.0.85"
+version = "2.0.104"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "5023162dfcd14ef8f32034d8bcd4cc5ddc61ef7a247c024a33e24e1f24d21b56"
+checksum = "17b6f705963418cdb9927482fa304bc562ece2fdd4f616084c50b7023b435a40"
 dependencies = [
  "proc-macro2",
  "quote",
···
 
 [[package]]
 name = "unicode-ident"
-version = "1.0.13"
+version = "1.0.18"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e91b56cd4cadaeb79bbf1a5645f6b4f8dc5bde8834ad5894a8db35fda9efa1fe"
+checksum = "5a5f39404a5da50712a4c1eecf25e90dd62b613502b7e925fd4e4d19b5c96512"
 
 [[package]]
 name = "walkdir"

pkgs/build-support/build-fhsenv-bubblewrap/rootfs-builder/src/main.rs

···
     root_index: usize,
 }
 
+const FHSENV_MARKER_FILE: &str = "nix-support/is-fhsenv";
+
 fn build_reference_map(refs: Vec<RefGraphNode>) -> HashMap<PathBuf, Vec<PathBuf>> {
     refs.into_iter()
         .map(|mut gn| {
···
     let mut candidates: HashMap<_, Vec<_>> = HashMap::new();
 
     for (path, priority) in paths {
+        if path.join(FHSENV_MARKER_FILE).exists() {
+            // is another fhsenv, skip it
+            continue;
+        }
+
         for entry in WalkDir::new(&path).follow_links(true) {
             let entry: PathBuf = match entry {
                 Ok(ent) => {
···
                         // could be a broken symlink, that's fine, we still want to handle those
                         Some(_) => e
                             .path()
-                            .ok_or_else(|| anyhow!("I/O error when walking {path:?}"))?
+                            .ok_or_else(|| anyhow!("I/O error when walking {}", path.display()))?
                             .into(),
                         None => {
                             // symlink loop
···
             .parent()
             .ok_or(anyhow!("destination directory is root"))
             .with_context(|| {
-                format!("When trying to determine destination directory for {full_dest:?}")
+                format!(
+                    "When trying to determine destination directory for {}",
+                    full_dest.display()
+                )
             })?;
         fs::create_dir_all(dest_dir)
-            .with_context(|| format!("When trying to create directory {dest_dir:?}"))?;
-        ufs::symlink(&src, &full_dest)
-            .with_context(|| format!("When symlinking {src:?} to {full_dest:?}"))?;
+            .with_context(|| format!("When trying to create directory {}", dest_dir.display()))?;
+        ufs::symlink(&src, &full_dest).with_context(|| {
+            format!(
+                "When symlinking {} to {}",
+                src.display(),
+                full_dest.display()
+            )
+        })?;
     }
+
+    let marker = out.join(FHSENV_MARKER_FILE);
+    fs::create_dir_all(
+        marker
+            .parent()
+            .ok_or(anyhow!("marker file is in root, this should never happen"))?,
+    )?;
+    fs::write(marker, [])?;
 
     Ok(())
 }
···
 
         paths = extend_to_closure(paths, &refs)?;
         paths32 = extend_to_closure(paths32, &refs)?;
-    };
+    }
 
     let plan = build_plan(paths, paths32)?;
 

pkgs/by-name/he/heroic-unwrapped/package.nix

···
   legendary-heroic,
   nile,
   comet-gog,
+  umu-launcher,
 }:
 
 let
···
     makeWrapper "${electron}/bin/electron" "$out/bin/heroic" \
       --inherit-argv0 \
       --set ELECTRON_FORCE_IS_PACKAGED 1 \
+      --suffix PATH ":" "${umu-launcher}/bin" \
       --add-flags --disable-gpu-compositing \
       --add-flags $out/opt/heroic/resources/app.asar \
       --add-flags "\''${NIXOS_OZONE_WL:+\''${WAYLAND_DISPLAY:+--ozone-platform-hint=auto --enable-features=WaylandWindowDecorations --enable-wayland-ime=true}}"

pkgs/by-name/he/heroic/package.nix

···
 {
-  buildFHSEnv,
+  steam,
   heroic-unwrapped,
   extraPkgs ? pkgs: [ ],
   extraLibraries ? pkgs: [ ],
 }:
 
-buildFHSEnv {
+steam.buildRuntimeEnv {
   pname = "heroic";
-  inherit (heroic-unwrapped) version;
+  inherit (heroic-unwrapped) version meta;
 
   runScript = "heroic";
 
-  # Many Wine and native games need 32-bit libraries.
-  multiArch = true;
-
-  # required by Electron
-  unshareIpc = false;
-
-  targetPkgs =
-    pkgs:
-    with pkgs;
-    [
-      heroic-unwrapped
-      gamemode
-      curl
-      gawk
-      zenity
-      kdePackages.kdialog
-      mangohud
-      net-tools
-      opencl-headers
-      p7zip
-      pciutils
-      perl
-      psmisc
-      python3
-      umu-launcher
-      unzip
-      which
-      xorg.xrandr
-      zstd
-    ]
-    ++ extraPkgs pkgs;
-
-  multiPkgs =
-    let
-      xorgDeps =
-        pkgs: with pkgs.xorg; [
-          libICE
-          libpthreadstubs
-          libSM
-          libX11
-          libXaw
-          libxcb
-          libXcomposite
-          libXcursor
-          libXdmcp
-          libXext
-          libXfixes
-          libXi
-          libXinerama
-          libXmu
-          libXrandr
-          libXrender
-          libXScrnSaver
-          libXt
-          libXtst
-          libXv
-          libXxf86vm
-        ];
-      gstreamerDeps =
-        pkgs: with pkgs.gst_all_1; [
-          gstreamer
-          gst-plugins-base
-          gst-plugins-good
-          gst-plugins-ugly
-          gst-plugins-bad
-          gst-libav
-        ];
-    in
-    pkgs:
-    with pkgs;
-    [
-      alsa-lib
-      alsa-plugins
-      bash
-      cabextract
-      cairo
-      coreutils
-      cups
-      dbus
-      freealut
-      freetype
-      fribidi
-      giflib
-      glib
-      gnutls
-      gtk3
-      icu
-      lcms2
-      libevdev
-      libgcrypt
-      libGLU
-      libglvnd
-      libgpg-error
-      libgudev
-      libjpeg
-      libkrb5
-      libmpeg2
-      libogg
-      libopus
-      libpng
-      libpulseaudio
-      libselinux
-      libsndfile
-      libtheora
-      libtiff
-      libunwind
-      libusb1
-      libv4l
-      libva
-      libvdpau
-      libvorbis
-      libvpx
-      libwebp
-      libxkbcommon
-      libxml2
-      mpg123
-      ncurses
-      ocl-icd
-      openal
-      openldap
-      openssl
-      pango
-      pipewire
-      samba4
-      sane-backends
-      SDL2
-      speex
-      sqlite
-      udev
-      unixODBC
-      util-linux
-      vulkan-loader
-      wayland
-      zlib
-    ]
-    ++ xorgDeps pkgs
-    ++ gstreamerDeps pkgs
-    ++ extraLibraries pkgs;
+  extraPkgs = pkgs: [ heroic-unwrapped ] ++ extraPkgs pkgs;
+  inherit extraLibraries;
 
   extraInstallCommands = ''
     mkdir -p $out/share
     ln -s ${heroic-unwrapped}/share/applications $out/share
     ln -s ${heroic-unwrapped}/share/icons $out/share
   '';
-
-  meta = heroic-unwrapped.meta;
 }

pkgs/by-name/st/steam/package.nix

···
   privateTmp ? true, # if the steam bubblewrap should isolate /tmp
 }:
 let
-  steamEnv =
+  buildRuntimeEnv =
     {
-      name,
-      runScript,
-      passthru ? { },
-      meta ? { },
-    }:
-    buildFHSEnv {
-      inherit
-        name
-        runScript
-        passthru
-        meta
-        privateTmp
-        ;
-
-      multiArch = true;
-      includeClosures = true;
-
-      # https://gitlab.steamos.cloud/steamrt/steam-runtime-tools/-/blob/main/docs/distro-assumptions.md#command-line-tools
-      targetPkgs =
-        pkgs:
-        with pkgs;
-        [
-          steam-unwrapped
+      extraPkgs ? pkgs: [ ],
+      extraLibraries ? pkgs: [ ],
+      extraProfile ? "",
+      extraPreBwrapCmds ? "",
+      extraBwrapArgs ? [ ],
+      extraEnv ? { },
+      ...
+    }@args:
+    buildFHSEnv (
+      (builtins.removeAttrs args [
+        "extraPkgs"
+        "extraLibraries"
+        "extraProfile"
+        "extraPreBwrapCmds"
+        "extraBwrapArgs"
+        "extraArgs"
+        "extraEnv"
+      ])
+      // {
+        inherit privateTmp;
 
-          bash
-          coreutils
-          file
-          lsb-release # not documented, called from Big Picture
-          pciutils # not documented, complains about lspci on startup
-          glibc_multi.bin
-          xdg-utils # calls xdg-open occasionally
-          xz
-          zenity
+        multiArch = true;
+        includeClosures = true;
 
-          # Steam expects it to be /sbin specifically
-          (pkgs.runCommand "sbin-ldconfig" { } ''
-            mkdir -p $out/sbin
-            ln -s /bin/ldconfig $out/sbin/ldconfig
-          '')
+        # https://gitlab.steamos.cloud/steamrt/steam-runtime-tools/-/blob/main/docs/distro-assumptions.md#command-line-tools
+        targetPkgs =
+          pkgs:
+          with pkgs;
+          [
+            bash
+            coreutils
+            file
+            lsb-release # not documented, called from Big Picture
+            pciutils # not documented, complains about lspci on startup
+            glibc_multi.bin
+            xdg-utils # calls xdg-open occasionally
+            xz
+            zenity
 
-          # crashes on startup if it can't find libX11 locale files
-          (pkgs.runCommand "xorg-locale" { } ''
-            mkdir -p $out
-            ln -s ${xorg.libX11}/share $out/share
-          '')
-        ]
-        ++ extraPkgs pkgs;
+            # Steam expects it to be /sbin specifically
+            (pkgs.runCommand "sbin-ldconfig" { } ''
+              mkdir -p $out/sbin
+              ln -s /bin/ldconfig $out/sbin/ldconfig
+            '')
 
-      # https://gitlab.steamos.cloud/steamrt/steam-runtime-tools/-/blob/main/docs/distro-assumptions.md#shared-libraries
-      multiPkgs =
-        pkgs:
-        with pkgs;
-        [
-          glibc
-          libxcrypt
-          libGL
+            # crashes on startup if it can't find libX11 locale files
+            (pkgs.runCommand "xorg-locale" { } ''
+              mkdir -p $out
+              ln -s ${xorg.libX11}/share $out/share
+            '')
+          ]
+          ++ extraPkgs pkgs;
 
-          libdrm
-          libgbm
-          udev
-          libudev0-shim
-          libva
-          vulkan-loader
+        # https://gitlab.steamos.cloud/steamrt/steam-runtime-tools/-/blob/main/docs/distro-assumptions.md#shared-libraries
+        multiPkgs =
+          pkgs:
+          with pkgs;
+          [
+            glibc
+            libxcrypt
+            libGL
 
-          networkmanager
-          # not documented, used for network status things in Big Picture
-          # FIXME: figure out how to only build libnm?
-          libcap # not documented, required by srt-bwrap
-        ]
-        ++ extraLibraries pkgs;
+            libdrm
+            libgbm
+            udev
+            libudev0-shim
+            libva
+            vulkan-loader
 
-      extraInstallCommands = lib.optionalString (steam-unwrapped != null) ''
-        ln -s ${steam-unwrapped}/share $out/share
-      '';
+            networkmanager
+            # not documented, used for network status things in Big Picture
+            # FIXME: figure out how to only build libnm?
+            libcap # not documented, required by srt-bwrap
+          ]
+          ++ extraLibraries pkgs;
 
-      profile = ''
-        # prevents log spam from SteamRT GTK trying to load host GIO modules
-        unset GIO_EXTRA_MODULES
+        profile = ''
+          # prevents log spam from SteamRT GTK trying to load host GIO modules
+          unset GIO_EXTRA_MODULES
 
-        # udev event notifications don't work reliably inside containers.
-        # SDL2 already tries to automatically detect flatpak and pressure-vessel
-        # and falls back to inotify-based discovery [1]. We make SDL2 do the
-        # same by telling it explicitly.
-        #
-        # [1] <https://github.com/libsdl-org/SDL/commit/8e2746cfb6e1f1a1da5088241a1440fd2535e321>
-        export SDL_JOYSTICK_DISABLE_UDEV=1
+          # udev event notifications don't work reliably inside containers.
+          # SDL2 already tries to automatically detect flatpak and pressure-vessel
+          # and falls back to inotify-based discovery [1]. We make SDL2 do the
+          # same by telling it explicitly.
+          #
+          # [1] <https://github.com/libsdl-org/SDL/commit/8e2746cfb6e1f1a1da5088241a1440fd2535e321>
+          export SDL_JOYSTICK_DISABLE_UDEV=1
 
-        # This is needed for IME (e.g. iBus, fcitx5) to function correctly on non-CJK locales
-        # https://github.com/ValveSoftware/steam-for-linux/issues/781#issuecomment-2004757379
-        export GTK_IM_MODULE='xim'
+          # This is needed for IME (e.g. iBus, fcitx5) to function correctly on non-CJK locales
+          # https://github.com/ValveSoftware/steam-for-linux/issues/781#issuecomment-2004757379
+          export GTK_IM_MODULE='xim'
 
-        # See https://gitlab.steamos.cloud/steamrt/steam-runtime-tools/-/blob/main/docs/distro-assumptions.md#graphics-driver
-        export LIBGL_DRIVERS_PATH=/run/opengl-driver/lib/dri:/run/opengl-driver-32/lib/dri
-        export __EGL_VENDOR_LIBRARY_DIRS=/run/opengl-driver/share/glvnd/egl_vendor.d:/run/opengl-driver-32/share/glvnd/egl_vendor.d
-        export LIBVA_DRIVERS_PATH=/run/opengl-driver/lib/dri:/run/opengl-driver-32/lib/dri
-        export VDPAU_DRIVER_PATH=/run/opengl-driver/lib/vdpau:/run/opengl-driver-32/lib/vdpau
+          # See https://gitlab.steamos.cloud/steamrt/steam-runtime-tools/-/blob/main/docs/distro-assumptions.md#graphics-driver
+          export LIBGL_DRIVERS_PATH=/run/opengl-driver/lib/dri:/run/opengl-driver-32/lib/dri
+          export __EGL_VENDOR_LIBRARY_DIRS=/run/opengl-driver/share/glvnd/egl_vendor.d:/run/opengl-driver-32/share/glvnd/egl_vendor.d
+          export LIBVA_DRIVERS_PATH=/run/opengl-driver/lib/dri:/run/opengl-driver-32/lib/dri
+          export VDPAU_DRIVER_PATH=/run/opengl-driver/lib/vdpau:/run/opengl-driver-32/lib/vdpau
 
-        # Steam gets confused by the symlinks to bind mounts to symlinks /etc/localtime ends up being, so help it out.
-        # See also: https://github.com/flathub/com.valvesoftware.Steam/blob/28481f09f33c12b6ac7421d13af9ed1523c54ec4/steam_wrapper/steam_wrapper.py#L160
-        if [ -z ''${TZ+x} ]; then
-          new_TZ="$(readlink -f /etc/localtime | grep -P -o '(?<=/zoneinfo/).*$')"
-          if [ $? -eq 0 ]; then
-            export TZ="$new_TZ"
+          # Steam gets confused by the symlinks to bind mounts to symlinks /etc/localtime ends up being, so help it out.
+          # See also: https://github.com/flathub/com.valvesoftware.Steam/blob/28481f09f33c12b6ac7421d13af9ed1523c54ec4/steam_wrapper/steam_wrapper.py#L160
+          if [ -z ''${TZ+x} ]; then
+            new_TZ="$(readlink -f /etc/localtime | grep -P -o '(?<=/zoneinfo/).*$')"
+            if [ $? -eq 0 ]; then
+              export TZ="$new_TZ"
+            fi
           fi
-        fi
 
-        set -a
-        ${lib.toShellVars extraEnv}
-        set +a
+          set -a
+          ${lib.toShellVars extraEnv}
+          set +a
 
-        ${extraProfile}
-      '';
+          ${extraProfile}
+        '';
 
-      inherit extraPreBwrapCmds;
+        inherit extraPreBwrapCmds;
 
-      extraBwrapArgs = [
-        # Steam will dump crash reports here, make those more accessible
-        "--bind-try /tmp/dumps /tmp/dumps"
-      ]
-      ++ extraBwrapArgs;
-    };
+        extraBwrapArgs = [
+          # Steam will dump crash reports here, make those more accessible
+          "--bind-try /tmp/dumps /tmp/dumps"
+        ]
+        ++ extraBwrapArgs;
+      }
+    );
 in
-steamEnv {
-  name = "steam";
+buildRuntimeEnv {
+  pname = "steam";
+  inherit (steam-unwrapped) version meta;
+
+  extraPkgs = pkgs: [ steam-unwrapped ] ++ extraPkgs pkgs;
+  inherit
+    extraLibraries
+    extraProfile
+    extraPreBwrapCmds
+    extraBwrapArgs
+    extraEnv
+    ;
 
   runScript = writeShellScript "steam-wrapped" ''
     exec steam ${extraArgs} "$@"
   '';
 
-  passthru.run = steamEnv {
-    name = "steam-run";
+  extraInstallCommands = ''
+    ln -s ${steam-unwrapped}/share $out/share
+  '';
 
-    runScript = writeShellScript "steam-run" ''
-      if [ $# -eq 0 ]; then
-        echo "Usage: steam-run command-to-run args..." >&2
-        exit 1
-      fi
+  passthru =
+    let
+      makeSteamRun =
+        package:
+        buildRuntimeEnv {
+          name = "steam-run";
 
-      exec "$@"
-    '';
+          extraPkgs = pkgs: package ++ extraPkgs pkgs;
 
-    meta = (steam-unwrapped.meta or { }) // {
-      description = "Run commands in the same FHS environment that is used for Steam";
-      mainProgram = "steam-run";
-      name = "steam-run";
-      # steam-run itself is just a script that lives in nixpkgs (which is licensed under MIT).
-      # steam is a dependency and already unfree, so normal steam-run will not install without
-      # allowing unfree packages or appropriate `allowUnfreePredicate` rules.
-      license = lib.licenses.mit;
-    };
-  };
+          inherit
+            extraLibraries
+            extraProfile
+            extraPreBwrapCmds
+            extraBwrapArgs
+            extraEnv
+            ;
 
-  meta = (steam-unwrapped.meta or { }) // {
-    description = "Steam dependencies (dummy package, do not use)";
-  };
+          runScript = writeShellScript "steam-run" ''
+            if [ $# -eq 0 ]; then
+              echo "Usage: steam-run command-to-run args..." >&2
+              exit 1
+            fi
+
+            exec "$@"
+          '';
+
+          meta = {
+            description = "Run commands in the same FHS environment that is used for Steam";
+            mainProgram = "steam-run";
+            name = "steam-run";
+            license = lib.licenses.mit;
+          };
+        };
+    in
+    {
+      inherit buildRuntimeEnv;
+
+      run = makeSteamRun [ steam-unwrapped ];
+      run-free = makeSteamRun [ ];
+    };
 }

pkgs/by-name/um/umu-launcher/package.nix

···
 {
-  buildFHSEnv,
   lib,
   steam,
   umu-launcher-unwrapped,
···
   extraLibraries ? pkgs: [ ],
   extraProfile ? "", # string to append to shell profile
   extraEnv ? { }, # Environment variables to include in shell profile
-  withMultiArch ? true, # Many Wine games need 32-bit libraries.
 }:
-let
-  # Steam is not a dependency, but we re-use some of its implementation
-  steam' = steam.override {
-    inherit extraEnv extraProfile;
-  };
-in
-buildFHSEnv {
+steam.buildRuntimeEnv {
   pname = "umu-launcher";
   inherit (umu-launcher-unwrapped) version meta;
 
-  targetPkgs =
-    pkgs:
-    [
-      # Use umu-launcher-unwrapped from the package args, to support overriding
-      umu-launcher-unwrapped
-    ]
-    ++ extraPkgs pkgs;
-  multiPkgs = extraLibraries;
-  multiArch = withMultiArch;
+  extraPkgs = pkgs: [ umu-launcher-unwrapped ] ++ extraPkgs pkgs;
+  inherit
+    extraLibraries
+    extraProfile
+    extraEnv
+    ;
 
   executableName = umu-launcher-unwrapped.meta.mainProgram;
   runScript = lib.getExe umu-launcher-unwrapped;
 
+  # Legendary spawns UMU, doesn't wait for it to exit,
+  # and immediately exits itself. This makes it so we can't
+  # die with parent, because parent is already dead.
+  dieWithParent = false;
+
   extraInstallCommands = ''
     ln -s ${umu-launcher-unwrapped}/lib $out/lib
     ln -s ${umu-launcher-unwrapped}/share $out/share
   '';
-
-  # For umu & proton, we need roughly the same environment as Steam.
-  # For simplicity, we use Steam's `profile` implementation.
-  # See https://github.com/NixOS/nixpkgs/pull/381047
-  # And https://github.com/NixOS/nixpkgs/issues/297662#issuecomment-2647656699
-  inherit (steam'.args) profile;
 }

pkgs/top-level/all-packages.nix

···
   springLobby = callPackage ../games/spring/springlobby.nix { };
 
   steam-run = steam.run;
-
-  # This exists so Hydra tries to build all of Steam's dependencies.
-  steam-fhsenv-without-steam = steam.override { steam-unwrapped = null; };
-
-  steam-run-free = steam-fhsenv-without-steam.run;
+  steam-run-free = steam.run-free;
 
   steamback = python3.pkgs.callPackage ../tools/games/steamback { };