btrfs-progs: tests: check there are no unprintable characters in btrfs-image -ss output

Signed-off-by: David Sterba <dsterba@suse.com>

tests/misc-tests/026-image-non-printable-chars/test.sh

@@ -0,0 +1,30 @@
+#!/bin/bash
+# check that sanitized names with matching crc do not contain unprintable
+# characters, namely 0x7f
+
+source "$TOP/tests/common"
+
+check_prereq mkfs.btrfs
+check_prereq btrfs
+
+prepare_test_dev
+
+run_check "$TOP/mkfs.btrfs" -f "$TEST_DEV"
+run_check_mount_test_dev
+run_check $SUDO_HELPER chmod a+rw "$TEST_MNT"
+
+# known to produce char 0x7f == 127
+touch "$TEST_MNT/|5gp!"
+
+run_check_umount_test_dev
+
+run_check $SUDO_HELPER "$TOP/btrfs-image" -ss "$TEST_DEV" img
+run_check $SUDO_HELPER "$TOP/btrfs-image" -r img img.restored
+run_check_stdout $SUDO_HELPER "$TOP/btrfs" inspect-internal dump-tree img.restored > img.dump
+
+ch7f=$(echo -en '\x7f')
+if grep -q "$ch7f" img.dump; then
+	_fail "found char 0x7f in the sanitized names"
+fi
+
+rm -f -- img img.restored img.dump