citrix_receiver: allow custom certs and hooks for the installation

Sometimes it's required to modify some parts of the Citrix build on
their own which is why `{pre,post}Install` hooks can be quite helpful.

Additionally some corporate clients use their own certificates that
aren't stored as trusted ones in the `cacert` package with all of the
trusted certs by Mozilla.

Now it's possible to add custom certs like this:

``` nix
with import <nixpkgs> { config.allowUnfree = true; };

let path = ../../Downloads/custom-corporate-cert.pem; in
citrix_receiver.override {
  extraCerts = [ path ];
}
```

pkgs/applications/networking/remote/citrix-receiver/default.nix

@@ -156,7 +156,7 @@ let
         '';
       };
 
-      phases = [ "unpackPhase" "installPhase" ];
+      dontBuild = true;
 
       sourceRoot = ".";
 
@@ -203,6 +203,8 @@ let
       };
 
       installPhase = ''
+        runHook preInstall
+
         export ICAInstDir="$out/opt/citrix-icaclient"
 
         sed -i \
@@ -262,13 +264,15 @@ let
 
         # We introduce a dependency on the source file so that it need not be redownloaded everytime
         echo $src >> "$out/share/nix_dependencies.pin"
+
+        runHook postInstall
       '';
 
       meta = with stdenv.lib; {
         license     = stdenv.lib.licenses.unfree;
         inherit homepage;
         description = "Citrix Receiver";
-        maintainers = with maintainers; [ obadz a1russell ];
+        maintainers = with maintainers; [ obadz a1russell ma27 ];
         platforms   = platforms.linux;
       };
     };

pkgs/applications/networking/remote/citrix-receiver/wrapper.nix

@@ -0,0 +1,19 @@
+{ citrix_receiver, extraCerts ? [], symlinkJoin }:
+
+let
+
+  mkCertCopy = certPath:
+    "cp ${certPath} $out/opt/citrix-icaclient/keystore/cacerts/";
+
+in
+
+if builtins.length extraCerts == 0 then citrix_receiver else symlinkJoin {
+  name = "citrix-with-extra-certs-${citrix_receiver.version}";
+  paths = [ citrix_receiver ];
+
+  postBuild = ''
+    ${builtins.concatStringsSep "\n" (map mkCertCopy extraCerts)}
+
+    sed -i -E "s,-icaroot (.+citrix-icaclient),-icaroot $out/opt/citrix-icaclient," $out/bin/wfica
+  '';
+}