From ab4295ea0fac84bcc245180db5af5ea007c40358 Mon Sep 17 00:00:00 2001
From: Sergei Trofimovich <slyich@gmail.com>
Date: Fri, 8 Aug 2025 21:50:01 +0100
Subject: [PATCH] stdenv/setup.sh: fix isMachO detection after bash-5.3 update

Without the change isMachO fails to work on UTF-8 locales as `read -u 4`
decoders 4 UTF-8 chars and not 4 bytes. `LANG=C` forces it to read bytes.

Closes: https://github.com/NixOS/nixpkgs/issues/431934
---
 pkgs/stdenv/generic/setup.sh | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/pkgs/stdenv/generic/setup.sh b/pkgs/stdenv/generic/setup.sh
index 5a2121dc36be..81e65129b88f 100644
--- a/pkgs/stdenv/generic/setup.sh
+++ b/pkgs/stdenv/generic/setup.sh
@@ -519,7 +519,7 @@ isELF() {
     local fd
     local magic
     exec {fd}< "$fn"
-    read -r -n 4 -u "$fd" magic
+    LANG=C read -r -n 4 -u "$fd" magic
     exec {fd}<&-
     if [ "$magic" = $'\177ELF' ]; then return 0; else return 1; fi
 }
@@ -530,7 +530,7 @@ isMachO() {
     local fd
     local magic
     exec {fd}< "$fn"
-    read -r -n 4 -u "$fd" magic
+    LANG=C read -r -n 4 -u "$fd" magic
     exec {fd}<&-
 
     # nix uses 'declare -F' in get-env.sh to retrieve the loaded functions.
@@ -559,7 +559,7 @@ isScript() {
     local fd
     local magic
     exec {fd}< "$fn"
-    read -r -n 2 -u "$fd" magic
+    LANG=C read -r -n 2 -u "$fd" magic
     exec {fd}<&-
     if [[ "$magic" =~ \#! ]]; then return 0; else return 1; fi
 }