mr: Check if unsafe ENV variables are set

If e.g. $GIT_DIR is set, it's near certain that the user is about to
shoot their own foot so we abort.

diff --git a/mr b/mr
index 7fa3180f56259753a4292b4d8846e60eeb901684..e0d27a125a003471e8e4ca09b8bbf992ef43559f 100755 (executable)
--- a/mr
+++ b/mr
@@ -1879,6 +1879,13 @@ sub getopts {
        }
 }
 
+sub check {
+       my @env = qw(GIT_DIR VCSH_COMMAND);
+       foreach (@env) {
+               die ("mr: environment variable '$_' is set. You are about to shoot your own foot.\n") if ($ENV{$_});
+       }
+}
+
 sub init {
        $SIG{INT}=sub {
                print STDERR "mr: interrupted\n";
@@ -1914,6 +1921,7 @@ sub exitstats {
 
 sub main {
        getopts();
+       check();
        init();
        help(@ARGV) if $ARGV[0] eq 'help';