Merge pull request #255463 from emilylange/stdenv/patch-shebangs-trailing-newline

patch-shebangs: fix crash with shebang without trailing newline

pkgs/build-support/setup-hooks/patch-shebangs.sh

@@ -72,7 +72,10 @@ patchShebangs() {
     while IFS= read -r -d $'\0' f; do
         isScript "$f" || continue
 
-        read -r oldInterpreterLine < "$f"
+        # read exits unclean if the shebang does not end with a newline, but still assigns the variable.
+        # So if read returns errno != 0, we check if the assigned variable is non-empty and continue.
+        read -r oldInterpreterLine < "$f" || [ "$oldInterpreterLine" ]
+
         read -r oldPath arg0 args <<< "${oldInterpreterLine:2}"
 
         if [[ -z "${pathName:-}" ]]; then

pkgs/test/stdenv/patch-shebangs.nix

@@ -72,11 +72,26 @@ let
       };
     };
 
+    without-trailing-newline = stdenv.mkDerivation {
+      name = "without-trailing-newline";
+      strictDeps = false;
+      dontUnpack = true;
+      installPhase = ''
+        mkdir -p $out/bin
+        printf "#!/bin/bash" > $out/bin/test
+        chmod +x $out/bin/test
+        dontPatchShebangs=
+      '';
+      passthru = {
+        assertion = "grep '^#!${stdenv.shell}' $out/bin/test > /dev/null";
+      };
+    };
+
   };
 in
 stdenv.mkDerivation {
   name = "test-patch-shebangs";
-  passthru = { inherit (tests) bad-shebang ignores-nix-store updates-nix-store split-string; };
+  passthru = { inherit (tests) bad-shebang ignores-nix-store updates-nix-store split-string without-trailing-newline; };
   buildCommand = ''
     validate() {
       local name=$1