switch_root: more clear error messages

Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>

1 files changed, 6 insertions, 4 deletions

diff --git a/util-linux/switch_root.c b/util-linux/switch_root.c
index ff0551843..e2da119de 100644
--- a/util-linux/switch_root.c
+++ b/util-linux/switch_root.c
@@ -85,12 +85,14 @@ int switch_root_main(int argc UNUSED_PARAM, char **argv)
         // Additional sanity checks: we're about to rm -rf /, so be REALLY SURE
         // we mean it. I could make this a CONFIG option, but I would get email
         // from all the people who WILL destroy their filesystems.
+        if (stat("/init", &st) != 0 || !S_ISREG(st.st_mode)) {
+                bb_error_msg_and_die("/init is not a regular file");
+        }
         statfs("/", &stfs); // this never fails
-        if (stat("/init", &st) != 0 || !S_ISREG(st.st_mode)
-         || ((unsigned)stfs.f_type != RAMFS_MAGIC
-             && (unsigned)stfs.f_type != TMPFS_MAGIC)
+        if ((unsigned)stfs.f_type != RAMFS_MAGIC
+         && (unsigned)stfs.f_type != TMPFS_MAGIC
         ) {
-                bb_error_msg_and_die("not rootfs");
+                bb_error_msg_and_die("root filesystem is not ramfs/tmpfs");
         }
 
         // Zap everything out of rootdev