From d0d5b30f6abef866365b1a1b7714fd5d9faafc28 Mon Sep 17 00:00:00 2001
From: Michael Raitza <michael.raitza@tu-dresden.de>
Date: Wed, 17 Feb 2021 18:42:17 +0100
Subject: [PATCH] Add src directory location info with cwd and (relative) rcwd

---
 builder.nix | 21 +++++++++++----------
 nixredo     |  2 +-
 2 files changed, 12 insertions(+), 11 deletions(-)

diff --git a/builder.nix b/builder.nix
index 5ecf5c2..efb296f 100644
--- a/builder.nix
+++ b/builder.nix
@@ -1,4 +1,4 @@
-buildArgs@{ lib ? import ./lib.nix {}, nixpkgs ? <nixpkgs>, pkgs ? import nixpkgs {}, root, filter ? [] }:
+buildArgs@{ lib ? import ./lib.nix {}, nixpkgs ? <nixpkgs>, pkgs ? import nixpkgs {}, root, cwd, filter ? [] }:
 let
   inherit (lib) searchPath whichdo d1 d2;
 
@@ -14,10 +14,13 @@ let
       # Funktionalise pkgs; our main entry point to resolve default*nix build scripts.
       getSrc = filterSource
         (path: type: baseNameOf path != ".git" && baseNameOf path != ".envrc" && (all (x: path != x) filter));
+
+      rcwd = dirOf (removePrefix (root + "/") builder);
+
       funcPkgs = {
         __functor = self: arg: resolve arg;
-        redo.getSrc = getSrc;
-      } // pkgs;
+        inherit pkgs getSrc cwd rcwd;
+      };
 
       _builder = let
         imported = (tryEval (let
@@ -28,17 +31,15 @@ let
          then imported.value
          else {
            src = getSrc (/. + root);
-           builder = let
-             relPath = dirOf (removePrefix (root + "/") builder);
-           in ''
+           builder = ''
              #!/bin/sh
              set -e
              pout=$(mktemp -u -p $PWD)
              cp -r --reflink=auto --no-preserve=mode "$src/" src
-             cd src/${relPath}
-             ${/. + builder} $d1 $d2 $out >$pout
-             if [ -e $out -a -s $pout ]; then
-               printf "Error: %s wrote to stdout and created \$3\n" "$d1" >&2
+             cd src/${rcwd}
+             ${/. + builder} "$d1" "$d2" "$out" >$pout
+             if [ -e "$out" -a -s "$pout" ]; then
+               printf "Error: %s wrote to stdout and created \$3\n" "${baseNameOf builder}" >&2
                exit 207
              elif [ -s $pout ]; then
                mv $pout $out
diff --git a/nixredo b/nixredo
index af025bf..0953911 100644
--- a/nixredo
+++ b/nixredo
@@ -27,7 +27,7 @@ out=$(nix -vL --show-trace build ${NIXREDO_ROOT:+--store "$NIXREDO_ROOT"} \
           --option auto-optimise-store true --option substituters daemon \
           --option keep-failed true --option keep-outputs true \
           --impure --json --no-link \
-          --expr " import @buildernix@ { lib = import @libnix@ {}; root =\"$S\"; filter = [ \"$filter\" \"$f\" ]; } \"$f\"" |
+          --expr " import @buildernix@ { lib = import @libnix@ {}; root =\"$S\"; cwd = \"$PWD\"; filter = [ \"$filter\" \"$f\" ]; } \"$f\"" |
           @jq@ -r '.[0].outputs.out')
 [ -n "$out" ] || exit 127
 ln -s "${NIXREDO_ROOT+$NIXREDO_ROOT}$out" "$3"