iotests/308: Test +w on read-only FUSE exports

Test that +w on read-only FUSE exports returns an EROFS error.  u+x on
the other hand should work.  (There is no special reason to choose u+x
here, it simply is like +w another flag that is not set by default.)

Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-Id: <20210625142317.271673-6-mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

2 files changed, 15 insertions, 0 deletions

diff --git a/tests/qemu-iotests/308 b/tests/qemu-iotests/308
index d13a9a969c..6b386bd523 100755
--- a/tests/qemu-iotests/308
+++ b/tests/qemu-iotests/308
@@ -170,6 +170,17 @@ fuse_export_add 'export-mp' "'mountpoint': '$EXT_MP'"
 # Check that the export presents the same data as the original image
 $QEMU_IMG compare -f raw -F $IMGFMT -U "$EXT_MP" "$TEST_IMG"
 
+# Some quick chmod tests
+stat -c 'Permissions pre-chmod: %a' "$EXT_MP"
+
+# Verify that we cannot set +w
+chmod u+w "$EXT_MP" 2>&1 | _filter_testdir | _filter_imgfmt
+stat -c 'Permissions post-+w: %a' "$EXT_MP"
+
+# But that we can set, say, +x (if we are so inclined)
+chmod u+x "$EXT_MP" 2>&1 | _filter_testdir | _filter_imgfmt
+stat -c 'Permissions post-+x: %a' "$EXT_MP"
+
 echo
 echo '=== Mount over existing file ==='
 
diff --git a/tests/qemu-iotests/308.out b/tests/qemu-iotests/308.out
index 0e9420645f..fc47bb11a2 100644
--- a/tests/qemu-iotests/308.out
+++ b/tests/qemu-iotests/308.out
@@ -50,6 +50,10 @@ wrote 67108864/67108864 bytes at offset 0
           } }
 {"return": {}}
 Images are identical.
+Permissions pre-chmod: 400
+chmod: changing permissions of 'TEST_DIR/t.IMGFMT.fuse': Read-only file system
+Permissions post-+w: 400
+Permissions post-+x: 500
 
 === Mount over existing file ===
 {'execute': 'block-export-add',