OpenSSH: allow users to configure --sysconfdir via $NIXPKGS_CONFIG

The OpenSSH binaries built by the expression by default expect system-wide
configuration files in "/etc/ssh", which is a bit of an impurity (and certainly
inconsistent with the way other package handle --sysconfdir in Nix). Those who
prefer a clean installation, can now configure that directory path.

Adding the line "openssh = { etcDir = null; };" to $NIXPKGS_CONFIG configures
OpenSSH to use the default location, i.e. $out/etc. Setting that attribute to a
string will configure OpenSSH to use that concrete path instead.

svn path=/nixpkgs/trunk/; revision=17570

pkgs/tools/networking/openssh/default.nix

@@ -1,5 +1,6 @@
 { stdenv, fetchurl, zlib, openssl, perl
 , pamSupport ? false, pam ? null
+, etcDir ? null
 }:
 
 assert pamSupport -> pam != null;
@@ -18,13 +19,13 @@ stdenv.mkDerivation rec {
 
   configureFlags = "
     --with-mantype=man
-    ${if pamSupport then "--with-pam" else ""}
+    ${if pamSupport then "--with-pam" else "--without-pam"}
+    ${if etcDir != null then "--sysconfdir=${etcDir}" else ""}
   ";
 
   preConfigure = "
     configureFlags=\"$configureFlags --with-privsep-path=$out/empty\"
     ensureDir $out/empty
-    substituteInPlace pathnames.h --replace 'SSHDIR \"/ssh_config\"' '\"/etc/ssh/ssh_config\"'
   ";
 
   postInstall = "

pkgs/top-level/all-packages.nix

@@ -1182,6 +1182,7 @@ let
   openssh = import ../tools/networking/openssh {
     inherit fetchurl stdenv zlib openssl pam perl;
     pamSupport = getPkgConfig "openssh" "pam" true;
+    etcDir = getConfig [ "openssh" "etcDir" ] "/etc/ssh";
   };
 
   openvpn = import ../tools/networking/openvpn {