commit c17063d377daf6227b696e83a4fe6325da8d2c9b
Author: Guillaume Bouchard <guillaum.bouchard@gmail.com>
Date:   Sat Sep 16 13:45:18 2017 +0200

    First version

diff --git a/README.md b/README.md
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+This tool tries to solve the "OpenGL" problem on nix.
+
+# Motivation
+
+You use Nix on any distribution, and any GL application installed fails with this error:
+
+```
+$ program
+libGL error: unable to load driver: i965_dri.so
+libGL error: driver pointer missing
+libGL error: failed to load driver: i965
+libGL error: unable to load driver: i965_dri.so
+libGL error: driver pointer missing
+libGL error: failed to load driver: i965
+libGL error: unable to load driver: swrast_dri.so
+libGL error: failed to load driver: swrast
+```
+
+This library contains a wrapper which is able to launch GL application:
+
+```
+nixGL program
+```
+
+# Installation / Usage
+
+Clone this git repository:
+
+```
+git clone https://github.com/guibou/nixGL
+```
+
+(Optional) installation:
+
+```
+cd nixGL
+nix-build
+nix-env -i ./result
+```
+
+Usage:
+
+```
+nixGL program args
+```
+
+# Limitations
+
+The idea is really simple and should work reliably. However there is still two configurations variables hardcoded in the wrapper. Open a bug / pull request if this does not work on your distribution / driver.
+
+## Library paths
+
+The path of where the `libGL.so` library can be found on your system, usually `/usr/lib`.
+
+## Name of the Nix package which contains `libGL.so`
+
+This package will be ignored by the wrapper. It is currently hardcoded as `mesa-noglu` but this can be fixed.
+
diff --git a/default.nix b/default.nix
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+{ system ? builtins.currentSystem }:
+
+let
+  pkgs = import <nixpkgs> { inherit system; };
+in
+rec {
+  nixGl = pkgs.stdenv.mkDerivation rec {
+     name = "nixGL-${version}";
+     version = "1.0.0";
+
+     buildInputs = [ pkgs.python3 pkgs.which pkgs.patchelf ];
+     outputs = [ "out" ];
+
+     src = ./.;
+
+     buildPhase = ''
+        mkdir -p $out/bin
+	'';
+
+     installPhase = ''
+        cp nixGL $out/bin
+	'';
+
+     meta = with pkgs.stdenv.lib; {
+         description = "A tool to launch OpenGL application on system other than NixOS";
+         homepage = "https://github.com/guibou/nixGL";
+     };
+  };
+}
diff --git a/nixGL b/nixGL
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+#!/usr/bin/env python
+import sys
+import os
+import subprocess
+
+# Any rpath with this pattern is ignored
+# TODO: perhaps libOpenGL.so in nix exists in other packages, we
+# should extend this list
+ignored = [b'mesa-noglu']
+
+# These are the list of system library which are added
+# TODO: extend this list for other systems
+systemLibs = [b"/usr/lib", b"/lib"]
+
+# extract command line and real path of the program
+cmd = (prog, *args) = sys.argv[1:]
+realProg = subprocess.check_output(["which", prog]).strip()
+
+# extract rpath of the program
+rpaths = map(bytes.strip, subprocess.check_output(
+    ['patchelf', '--print-rpath', realProg]).split(b':'))
+
+# filter rpath, removing ignored and empty paths
+dir = []
+
+for i in rpaths:
+    for c in ignored:
+        if c not in i:
+            if i.strip():
+                dir.append(i.strip())
+
+# build the new environment
+newenv = os.environb
+oldLdLibraryPath = newenv.get(b'LD_LIBRARY_PATH', b'').split()
+
+# The build order is IMPORTANT
+# first, any LD_LIBRARY_PATH from outside world. That's the default
+# behavior, LD_LIBRARY_PATH has precedance over rpath
+# Then, the different directory which satisfy our rpaths
+# The the system library where the openGL lib can be located
+
+# This ensure three properties:
+# a) system library (and libOpenGL.so) are used AFTER the one of nix
+# b) the executible respect the LD_LIBRARY_PATH for an user viewpoint
+newLibraryPath = oldLdLibraryPath + dir + systemLibs
+
+newenv.update({b'LD_LIBRARY_PATH': b':'.join(newLibraryPath)})
+os.execvpe(prog, cmd, newenv)