tomb: clean up and use gnupg 2 instead of gnupg 1

pkgs/os-specific/linux/tomb/default.nix

···
-{ stdenv, fetchurl, zsh, pinentry, cryptsetup, gnupg1orig, makeWrapper }:
-
-let
-    version = "2.4";
-in
+{ stdenv, lib, fetchFromGitHub, gettext, zsh, pinentry, cryptsetup, gnupg, makeWrapper }:
 
 stdenv.mkDerivation rec {
   name = "tomb-${version}";
+  version = "2.4";
 
-  src = fetchurl {
-    url = "https://files.dyne.org/tomb/Tomb-${version}.tar.gz";
-    sha256 = "1hv1w79as7swqj0n137vz8n8mwvcgwlvd91sdyssz41jarg7f1vr";
+  src = fetchFromGitHub {
+    owner  = "dyne";
+    repo   = "Tomb";
+    rev    = "v${version}";
+    sha256 = "192jpgn02mvi4d4inbq2q11zl7xw6njymvali7al8wmygkkycrw4";
   };
 
-  buildInputs = [ makeWrapper ];
+  nativeBuildInputs = [ makeWrapper ];
+
+  postPatch = ''
+    # if not, it shows .tomb-wrapped when running
+    substituteInPlace tomb \
+      --replace 'TOMBEXEC=$0' 'TOMBEXEC=tomb'
+  '';
 
   buildPhase = ''
     # manually patch the interpreter
···
   '';
 
   installPhase = ''
-    mkdir -p $out/bin
-    mkdir -p $out/share/man/man1
+    install -Dm755 tomb       $out/bin/tomb
+    install -Dm644 doc/tomb.1 $out/share/man/man1/tomb.1
 
-    cp tomb $out/bin/tomb
-    cp doc/tomb.1 $out/share/man/man1
+    # it works fine with gnupg v2, but it looks for an executable named gpg
+    ln -s ${gnupg}/bin/gpg2 $out/bin/gpg
 
     wrapProgram $out/bin/tomb \
-        --prefix PATH : "${pinentry}/bin" \
-        --prefix PATH : "${cryptsetup}/bin" \
-        --prefix PATH : "${gnupg1orig}/bin"
+      --prefix PATH : $out/bin:${lib.makeBinPath [ cryptsetup gettext pinentry ]}
   '';
 
-  meta = {
+  meta = with stdenv.lib; {
     description = "File encryption on GNU/Linux";
-    homepage = https://www.dyne.org/software/tomb/;
-    license = stdenv.lib.licenses.gpl3;
-    platforms = stdenv.lib.platforms.linux;
+    homepage    = https://www.dyne.org/software/tomb/;
+    license     = licenses.gpl3;
+    maintainers = with maintainers; [ peterhoeg ];
+    platforms   = platforms.linux;
   };
 }