Ensure pw userdel -u <invalid> do not try to remove root

Check the uid passed is actually a number as early as possible

MFC after:	1 week

2 files changed, 14 insertions, 0 deletions

diff --git a/usr.sbin/pw/pw_user.c b/usr.sbin/pw/pw_user.c
index 0b56b8134473..483148af4909 100644
--- a/usr.sbin/pw/pw_user.c
+++ b/usr.sbin/pw/pw_user.c
@@ -321,6 +321,9 @@ pw_user(struct userconf * cnf, int mode, struct cargs * args)
 			(a_uid = a_name)->ch = 'u';
 			a_name = NULL;
 		}
+	} else {
+		if (strspn(a_uid->val, "0123456789") != strlen(a_uid->val))
+			errx(EX_USAGE, "-u expects a number");
 	}
 
 	/*
diff --git a/usr.sbin/pw/tests/pw_delete.sh b/usr.sbin/pw/tests/pw_delete.sh
index 84a39db8ebef..0e9793913481 100755
--- a/usr.sbin/pw/tests/pw_delete.sh
+++ b/usr.sbin/pw/tests/pw_delete.sh
@@ -30,7 +30,18 @@ group_do_not_delete_wheel_if_group_unkown_body() {
 	atf_check -s exit:0 -o inline:"wheel:*:0:root\n" -x pw -V ${HOME} groupshow wheel
 }
 
+atf_test_case user_do_not_try_to_delete_root_if_user_unkown
+user_do_not_try_to_delete_root_if_user_unkown_head() {
+	atf_set "descr" "Make sure not to try to remove root if deleteing an unknown user"
+}
+
+user_do_not_try_to_delete_root_if_user_unkown_body() {
+	populate_etc_skel
+	atf_check -e inline:"pw: -u expects a number\n" -s exit:64 -x pw -V ${HOME} userdel -u plop
+}
+
 atf_init_test_cases() {
 	atf_add_test_case rmuser_seperate_group
 	atf_add_test_case group_do_not_delete_wheel_if_group_unkown
+	atf_add_test_case user_do_not_try_to_delete_root_if_user_unkown
 }