nixpatch.sh

#!/bin/sh
set -e
# Call with:
#
#    nixpatch.sh file_1 file_2 … file_n
#
# where each file_i is either an ELF executable or a shell script.
#
# This script will break badly if any of the arguments contain spaces.
# Don't use spaces in the file_i names!
#
# This script will replace each file with a symlink to a wrapepd version.
#
# This script will create a backup of each file as .file_i-original, and will
# skip files for which a backup already exists.
# 
# This script creates a .result-file_i symlink which points to NixOS's copy
# of the wrapper file. Removing or moving that hidden symlink will get
# the wrapper file garbage-collected by nix-collect-garbage.
for toPatch in $*; do
    if test -f "$toPatch" && ! test -e ".$toPatch-original"; then
		cat > .$toPatch-patch.nix <<-EOF
		{ stdenv, runCommand, fetchurl, makeFontsConf, makeWrapper
		, cairo, coreutils, fontconfig, freefont_ttf
		, glib, gmp, gtk2, libffi, libjpeg, libpng
		, libtool, mpfr, openssl, pango, poppler
		, readline, sqlite
		}:
		
		let
		
		  fontsConf = makeFontsConf {
		    fontDirectories = [ freefont_ttf ];
		  };
		
		  libPath = stdenv.lib.makeLibraryPath [
		    cairo
		    fontconfig
		    glib
		    gmp
		    gtk2
		    libjpeg
		    libpng
		    mpfr
		    openssl
		    pango
		    poppler
		    readline
		    sqlite
		  ];
		
		in
		runCommand "$toPatch" { nativeBuildInputs = [ makeWrapper ]; } ''
                  echo "Date is now (to get something unique): $(date)"
		  mkdir -p \$out/bin
		  cp -vi \${./$toPatch} \$out/bin/$toPatch
		  makeWrapper \$out/bin/$toPatch \$out/bin/$toPatch-wrapper --set LD_LIBRARY_PATH "\${libPath}"
		  chmod +x \$out/bin/$toPatch-wrapper
		''
		EOF
		nix-build -E "with import <nixpkgs>{}; callPackage ./.$toPatch-patch.nix {}" -o .$toPatch-result
		mv -i $toPatch .$toPatch-original
                ln -s .$toPatch-result/bin/$toPatch-wrapper $toPatch
		echo "Success: $toPatch."
	else
		echo "Skipping $toPatch, it is already patched."
	fi
done