From 698b92d7fb26680ebb0328c5c6c985071ff79a0a Mon Sep 17 00:00:00 2001
From: Brian Picciano <me@mediocregopher.com>
Date: Mon, 17 Jun 2024 12:43:47 +0200
Subject: Fix X server not picking up system library files

---
 alacritty/default.nix | 17 +++++------------
 awesome/default.nix   | 12 ++++++++++++
 nix/ld-utils.nix      | 22 ++++++++++++++++++++++
 nix/nixgl.nix         | 14 ++++++++++++++
 pkgs.nix              | 18 ++----------------
 5 files changed, 55 insertions(+), 28 deletions(-)
 create mode 100644 nix/ld-utils.nix
 create mode 100644 nix/nixgl.nix

diff --git a/alacritty/default.nix b/alacritty/default.nix
index e9a955d..9350884 100644
--- a/alacritty/default.nix
+++ b/alacritty/default.nix
@@ -57,27 +57,20 @@
   alacritty = pkgs.writeShellScriptBin "alacritty" ''
     set -e -x
 
-    host_ld_lib_path="$(
-      ldconfig -v 2>/dev/null \
-      | grep -v ^$'\t' \
-      | tr -s ':\n' ':' \
-      | head -c-1 \
-    )"
+    source "${pkgs.ldUtils}"
 
-    bin_ld_lib_path="$(
-      objdump -x ${pkgs.alacritty}/bin/alacritty \
-      | grep "RUNPATH" \
-      | awk '{print $2}' \
-    )"
+    host_ld_lib_path="$(host_ld_lib_path)"
 
     host_dri_path="$(
-      echo "$host_ld_lib_path" \
+      echo "$host_lib_path" \
       | tr -s ':' '\n' \
       | while read d; do if [ -d "$d/dri" ]; then echo "$d"/dri; fi; done \
       | tr '\n' ':' \
       | head -c-1
     )"
 
+    bin_ld_lib_path="$(bin_ld_lib_path "${pkgs.alacritty}/bin/alacritty")"
+
     # overwrite LD_LIBRARY_PATH such that the binary's ld search path is still
     # searched first, but afterwards the host's ld search path is looked
     # through. Similarly, the dri paths are set to be the hosts. This allows us
diff --git a/awesome/default.nix b/awesome/default.nix
index ca61ec5..acc6375 100644
--- a/awesome/default.nix
+++ b/awesome/default.nix
@@ -64,6 +64,10 @@ EOF
 
     set -e -x
 
+    # Set during startup of X server, but we don't want it inherited by
+    # everything downstream.
+    unset LD_LIBRARY_PATH
+
     # Turn off powersaving (fuck the environment)
     ${pkgs.xorg.xset}/bin/xset -dpms
     ${pkgs.xorg.xset}/bin/xset s off
@@ -103,6 +107,14 @@ EOF
 
   awesome = pkgs.writeShellScriptBin "awesome" ''
     export XORGCONFIG=${xorgConf}
+
+    # set the LD_LIBRARY_PATH to search both the libraries needed by X, but also
+    # those on the host, so that the video driver has access to them if it needs
+    # it.
+    source "${pkgs.ldUtils}"
+    x_ld_lib_path="$(bin_ld_lib_path "${pkgs.xorg.xinit}/bin/xinit")"
+    export LD_LIBRARY_PATH="$x_ld_lib_path":"$(host_ld_lib_path)"
+
     exec startx ${awesomeInner}
   '';
 
diff --git a/nix/ld-utils.nix b/nix/ld-utils.nix
new file mode 100644
index 0000000..6201b63
--- /dev/null
+++ b/nix/ld-utils.nix
@@ -0,0 +1,22 @@
+# ld-utils is a collection of functions which are intended to be sourced into
+# other scripts
+pkgs: pkgs.writeShellScript "ld-utils.sh" ''
+
+# returns the colon-delimited LD_LIBRARY_PATH for host installed libraries, as
+# determined by ldconfig.
+function host_ld_lib_path {
+  ldconfig -v 2>/dev/null \
+  | grep -v ^$'\t' \
+  | cut -d':' -f1 \
+  | tr -s ':\n' ':' \
+  | head -c-1
+}
+
+# bin_ld_lib_path returns the colon-delimited LD_LIBRARY_PATH which is embedded
+# into a particular binary as its RUNPATH.
+function bin_ld_lib_path {
+  objdump -x "$1" \
+  | grep "RUNPATH" \
+  | awk '{print $2}'
+}
+''
diff --git a/nix/nixgl.nix b/nix/nixgl.nix
new file mode 100644
index 0000000..82dbdfd
--- /dev/null
+++ b/nix/nixgl.nix
@@ -0,0 +1,14 @@
+pkgs: let
+
+  src = builtins.fetchTarball {
+    name = "nixgl-unstable";
+    url = "https://github.com/guibou/nixGL/archive/7165ffbccbd2cf4379b6cd6d2edd1620a427e5ae.tar.gz";
+    sha256 = "1wc85xqnq2wb008y9acb29jbfkc242m9697g2b8j6q3yqmfhrks1";
+  };
+
+  nixgl = (import src) {
+    inherit pkgs;
+    enable32bits = false;
+  };
+
+in nixgl.auto.nixGLDefault
diff --git a/pkgs.nix b/pkgs.nix
index 72dca4d..f7a3f55 100644
--- a/pkgs.nix
+++ b/pkgs.nix
@@ -7,22 +7,8 @@ rec {
     config = {
       allowUnfree = true;
       packageOverrides = pkgs: {
-
-        nixgl = let
-
-          src = builtins.fetchTarball {
-            name = "nixgl-unstable";
-            url = "https://github.com/guibou/nixGL/archive/7165ffbccbd2cf4379b6cd6d2edd1620a427e5ae.tar.gz";
-            sha256 = "1wc85xqnq2wb008y9acb29jbfkc242m9697g2b8j6q3yqmfhrks1";
-          };
-
-          nixgl = (import src) {
-            inherit pkgs;
-            enable32bits = false;
-          };
-
-        in nixgl.auto.nixGLDefault;
-
+        nixgl = (import ./nix/nixgl.nix) pkgs;
+        ldUtils = (import ./nix/ld-utils.nix) pkgs;
       };
     };
 
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