fetchFromGitHub: Allow private repos, hosted githubs

pkgs/build-support/fetchurl/default.nix

···
 
 , recursiveHash ? false
 
+, # Shell code to build a netrc file for BASIC auth
+  netrcPhase ? null
+
+, # Impure env vars (http://nixos.org/nix/manual/#sec-advanced-attributes)
+  # needed for netrcPhase
+  netrcImpureEnvVars ? []
+
 , # Shell code executed after the file has been fetched
   # successfully. This can do things like check or transform the file.
   postFetch ? ""
···
 
   outputHashMode = if (recursiveHash || executable) then "recursive" else "flat";
 
-  inherit curlOpts showURLs mirrorsFile impureEnvVars postFetch downloadToTemp executable;
+  inherit curlOpts showURLs mirrorsFile postFetch downloadToTemp executable;
+
+  impureEnvVars = impureEnvVars ++ netrcImpureEnvVars;
 
   # Doing the download on a remote machine just duplicates network
   # traffic, so don't do that.
   preferLocalBuild = true;
+
+  postHook = if netrcPhase == null then null else ''
+    ${netrcPhase}
+    curlOpts="$curlOpts --netrc-file $PWD/netrc"
+  '';
 
   inherit meta;
 }

pkgs/top-level/all-packages.nix

···
 
   fetchFromGitHub = {
     owner, repo, rev, name ? "${repo}-${rev}-src",
-    fetchSubmodules ? false,
+    fetchSubmodules ? false, private ? false,
+    githubBase ? "github.com", varPrefix ? null,
     ... # For hash agility
-  }@args:
+  }@args: assert private -> !fetchSubmodules;
   let
-    baseUrl = "https://github.com/${owner}/${repo}";
-    passthruAttrs = removeAttrs args [ "owner" "repo" "rev" "fetchSubmodules" ];
+    baseUrl = "https://${githubBase}/${owner}/${repo}";
+    passthruAttrs = removeAttrs args [ "owner" "repo" "rev" "fetchSubmodules" "private" "githubBase" "varPrefix" ];
+    varBase = "NIX${if varPrefix == null then "" else "_${varPrefix}"}_GITHUB_PRIVATE_";
   in if fetchSubmodules then
     fetchgit ({
       inherit name rev fetchSubmodules;
···
       inherit name;
       url = "${baseUrl}/archive/${rev}.tar.gz";
       meta.homepage = "${baseUrl}/";
+    } // lib.optionalAttrs private {
+      netrcPhase = ''
+        if [ -z "''$${varBase}USERNAME" -o -z "''$${varBase}PASSWORD" ]; then
+          echo "Error: Private fetchFromGitHub requires the nix building process (nix-daemon in multi user mode) to have the ${varBase}USERNAME and ${varBase}PASSWORD env vars set." >&2
+          exit 1
+        fi
+        cat > netrc <<EOF
+        machine ${githubBase}
+                login ''$${varBase}USERNAME
+                password ''$${varBase}PASSWORD
+        EOF
+      '';
+      netrcImpureEnvVars = [ "${varBase}USERNAME" "${varBase}PASSWORD" ];
     } // passthruAttrs) // { inherit rev; };
 
   fetchFromBitbucket = {