* A quick hack to make nix-prefetch-url support mirror:// URLs. It

requires that $NIXPKGS_ALL points at a Nixpkgs tree.

scripts/nix-prefetch-url.in

@@ -37,6 +37,7 @@ fi
 
 
 mkTempDir() {
+    if test -n "$tmpPath"; then return; fi
     local i=0
     while true; do
         if test -z "$TMPDIR"; then TMPDIR=/tmp; fi
@@ -64,6 +65,27 @@ doDownload() {
 }
 
 
+# Hack to support the mirror:// scheme from Nixpkgs.
+if test "${url:0:9}" = "mirror://"; then
+    if test -z "$NIXPKGS_ALL"; then
+        echo "Resolving mirror:// URLs requires Nixpkgs.  Please point \$NIXPKGS_ALL at a Nixpkgs tree." >&2
+        exit 1
+    fi
+
+    mkTempDir
+    nix-build "$NIXPKGS_ALL" -A resolveMirrorURLs --argstr url "$url" -o $tmpPath/urls > /dev/null
+
+    expanded=($(cat $tmpPath/urls))
+    if test "${#expanded[*]}" = 0; then
+        echo "$0: cannot resolve $url." >&2
+        exit 1
+    fi
+
+    echo "$url expands to ${expanded[*]} (using ${expanded[0]})" >&2
+    url="${expanded[0]}"
+fi
+
+
 # If we don't know the hash or a file with that hash doesn't exist,
 # download the file and add it to the store.
 if test -z "$finalPath"; then