modules/nix: Make the nix wrapper actually work

2 files changed, 13 insertions, 9 deletions

diff --git a/modules/by-name/ni/nix/module.nix b/modules/by-name/ni/nix/module.nix
index 31977d4c..391f38e5 100644
--- a/modules/by-name/ni/nix/module.nix
+++ b/modules/by-name/ni/nix/module.nix
@@ -24,10 +24,9 @@
     pkgs.lixPackageSets.latest.lix;
 
   nixWrapperBase = pkgs.writeShellApplication {
-    inherit (lix) name;
+    name = "nix";
 
     text = builtins.readFile ./nix_wrapper.sh;
-    inheritPath = false;
     runtimeInputs = [
       pkgs.lixPackageSets.latest.lix
       pkgs.libnotify
@@ -38,6 +37,9 @@
       pkgs.bc
     ];
 
+    # the wrapped nix command might call random other stuff.
+    inheritPath = true;
+
     derivationArgs = {
       inherit (lix) meta pname version;
     };
diff --git a/modules/by-name/ni/nix/nix_wrapper.sh b/modules/by-name/ni/nix/nix_wrapper.sh
index 55b12dc9..489f10f1 100755
--- a/modules/by-name/ni/nix/nix_wrapper.sh
+++ b/modules/by-name/ni/nix/nix_wrapper.sh
@@ -1,23 +1,25 @@
 #! /usr/bin/env sh
 
 set -eu
+_NIX_WRAPPER_FALLBACK="${_NIX_WRAPPER_FALLBACK-false}"
 
-notify-send "Running nix via the wrapper."
+me="$(basename "$0")"
 
+notify-send "Running '$me' via the wrapper."
 if [ "$_NIX_WRAPPER_FALLBACK" = "true" ]; then
     # Allow skipping the size check.
-    nix "$@"
+    "$me" "$@"
 else
     usage="$(btrfs filesystem usage /nix --raw 2>/dev/null)"
     avail="$(echo "$usage" | grep 'Device size:' | cut -f 3 | sed 's/ //g')"
     used="$(echo "$usage" | grep 'Used:' | cut -f 4 | head -n 1 | sed 's/ //g')"
-    perc="$(printf "scale=3\n%d / %d\n" "$used" "$avail" | bc)"
-    perc="$(printf "%d * 100\n" "$perc" | bc)"
+    perc="$(printf "scale=4\n%d / %d\n" "$used" "$avail" | bc)"
+    perc="$(printf "scale=2\n%s * 100\n" "0$perc" | bc)"
 
-    if test -gt "$perc" "0.2"; then
-        nix "$@"
+    if test "$(printf "%s >= 20\n" "$perc" | bc)" = "1"; then
+        "$me" "$@"
     else
-        echo "Not enough space free, in nix store: Only, $perc is still free."
+        echo "Not enough space free, in nix store: Only, $perc% is still free."
         exit 3
     fi
 fi