Merge pull request #6690 from maxim-belkin/harden-brew-2.0

bin/brew: unset functions that override builtins

bin/brew

@@ -19,6 +19,15 @@ symlink_target_directory() {
   quiet_cd "$directory" && quiet_cd "$target_dirname" && pwd -P
 }
 
+# Enable and use default Bash builtins rather than user-defined functions
+builtin enable compgen unset
+for cmd in $(builtin compgen -A builtin)
+do
+  builtin unset -f $cmd
+  builtin enable $cmd
+done
+unset cmd
+
 BREW_FILE_DIRECTORY="$(quiet_cd "${0%/*}/" && pwd -P)"
 HOMEBREW_BREW_FILE="${BREW_FILE_DIRECTORY%/}/${0##*/}"
 HOMEBREW_PREFIX="${HOMEBREW_BREW_FILE%/*/*}"