Added hacky fetchsvn component which allows users to fetch code over svn+ssh

svn path=/nixpkgs/trunk/; revision=11455

pkgs/build-support/fetchsvnssh/builder.sh

@@ -0,0 +1,15 @@
+source $stdenv/setup
+
+header "exporting $url (r$rev) into $out"
+
+if test "$sshSupport"; then
+    export SVN_SSH="$openssh/bin/ssh"
+fi
+
+# Pipe the "p" character into Subversion to force it to accept the
+# server's certificate.  This is perfectly safe: we don't care
+# whether the server is being spoofed --- only the cryptographic
+# hash of the output matters.
+expect -f $sshSubversion "$username" "$password" "$rev" "$url" $out
+
+stopNest

pkgs/build-support/fetchsvnssh/default.nix

@@ -0,0 +1,16 @@
+{stdenv, subversion, sshSupport ? false, openssh ? null, expect}: 
+{username, password, url, rev ? "HEAD", md5 ? "", sha256 ? ""}:
+
+stdenv.mkDerivation {
+  name = "svn-export-ssh";
+  builder = ./builder.sh;
+  buildInputs = [subversion expect];
+
+  outputHashAlgo = if sha256 == "" then "md5" else "sha256";
+  outputHashMode = "recursive";
+  outputHash = if sha256 == "" then md5 else sha256;
+  
+  sshSubversion = ./sshsubversion.exp;
+  
+  inherit username password url rev sshSupport openssh;
+}

pkgs/build-support/fetchsvnssh/sshsubversion.exp

@@ -0,0 +1,22 @@
+#!/nix/var/nix/profiles/default/bin/expect -f
+
+# Set variables
+set username [lindex $argv 0]
+set password [lindex $argv 1]
+set rev [lindex $argv 2]
+set url [lindex $argv 3]
+set out [lindex $argv 4]
+set timeout -1
+
+spawn svn export -r$rev svn+ssh://$username@$url $out
+match_max 100000
+
+expect "*continue connecting*" { send -- "yes\r"; expect "*?assword:*"; send -- "$password\r" } \
+       "*?assword:*" { send -- "$password\r" }
+
+expect "*?assword:*"
+send -- "$password\r"
+
+# Send blank line
+send -- "\r"
+expect eof

pkgs/top-level/all-packages.nix

@@ -345,6 +345,11 @@ let pkgs = rec {
     sshSupport = true;
   };
 
+  fetchsvnssh = import ../build-support/fetchsvnssh {
+    inherit stdenv subversion openssh expect;
+    sshSupport = true;
+  };
+
   # TODO do some testing
   fetchhg = import ../build-support/fetchhg {
     inherit stdenv mercurial nix;