1 files changed, 59 insertions, 0 deletions
diff --git a/tests/df/over-mount-device.sh b/tests/df/over-mount-device.sh
new file mode 100755
index 0000000..d6d40ac
--- /dev/null
+++ b/tests/df/over-mount-device.sh
@@ -0,0 +1,59 @@
+#!/bin/sh
+# Ensure that df /dev/loop0 errors out if overmounted by another device
+
+# Copyright (C) 2014-2023 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <https://www.gnu.org/licenses/>.
+
+. "${srcdir=.}/tests/init.sh"; path_prepend_ ./src
+print_ver_ df
+require_root_
+
+cwd=$(pwd)
+cleanup_() { cd /; umount "$cwd/mnt"; umount "$cwd/mnt"; }
+
+skip=0
+
+# Create 2 file systems
+for i in 1 2; do
+  dd if=/dev/zero of=blob$i bs=8192 count=200 > /dev/null 2>&1 \
+                                             || skip=1
+  mkfs -t ext2 -F blob$i \
+    || skip_ "failed to create ext2 file system"
+done
+
+# Mount both at the same place (eclipsing the first)
+mkdir mnt                                    || skip=1
+mount -oloop blob1 mnt                       || skip=1
+eclipsed_dev=$(df --o=source mnt | tail -n1) || skip=1
+mount -oloop blob2 mnt                       || skip=1
+
+test $skip = 1 \
+  && skip_ "insufficient mount/ext2 support"
+
+df . || skip_ "failed to lookup the device for the current dir"
+
+echo "df: cannot access '$eclipsed_dev': over-mounted by another device" > exp
+
+# We should get an error for the eclipsed device and continue
+df $eclipsed_dev . > out 2> err && fail=1
+
+# header and single entry in output
+test $(wc -l < out) = 2 || fail=1
+
+compare exp err || fail=1
+
+test "$fail" = 1 && dump_mount_list_
+
+Exit $fail