Property method invoked with surprising object path

[mulkieran]

This occurs when I invoke GetManagedObjects.

I have a property defined for an interface called Pool.
As the properties are being listed a method belonging to the Pool interface is invoked. It extracts the object path, but that object path is the object path that was used to call GetManagedObjects originally, and it is not an object path for an object that implements the Pool interface. This causes an error in my method as this situation is unexpected.

Obtaining the value of the property on an object path that does implement the Pool interface works fine.

Running dbus-0.4.1.

[diwic]

Sorry, not sure I follow:

As the properties are being listed a method belonging to the Pool interface is invoked.

Exactly how is that method invoked? Calling GetManagedObjects should just list properties, not invoke (other) methods.

[mulkieran]

The property is implemented by means of a method:

    let uuid_property = f.property::<&str, _>("Uuid", ())
        .access(Access::Read)
        .emits_changed(EmitsChangedSignal::Const)
        .on_get(get_pool_uuid);

and

let object_path = f.object_path(object_name, dbus_context.clone())
        .introspectable()
        .add(f.interface(interface_name, ())
            .add_m(create_filesystems_method)
            .add_m(destroy_filesystems_method)
            .add_m(add_cache_devs_method)
            .add_m(remove_cache_devs_method)
            .add_m(add_devs_method)
            .add_m(remove_devs_method)
            .add_m(rename_method)
            .add_p(name_property)
            .add_p(uuid_property));

and

fn get_pool_uuid(i: &mut IterAppend, p: &PropInfo<MTFn<TData>, TData>) -> Result<(), MethodErr> {
    let dbus_context = p.path.get_data();
    let object_path = p.path.get_name();
    let pools = dbus_context.pools.borrow();
    let name = try!(pools.get_by_first(object_path as &str)
        .ok_or(MethodErr::failed(&format!("no name for pool with object path {}", object_path))));
...

Currently the MethodError above is emitted when GetManagedObjects() is called, but not when the property is obtained directly from the pool.

The sequence below is:

1. Call GetManagedObjects() with success.
2. Create a Pool object.
3. Call GetManagedObjects() with failure.
4. Get the property directly from the pool with success.

[mulhern@dhcp-25-209 stratisd]$ busctl --user call org.storage.stratis1 /org/storage/stratis1 org.freedesktop.DBus.ObjectManager GetManagedObjects
a{oa{sa{sv}}} 1 "/org/storage/stratis1" 4 "org.freedesktop.DBus.Introspectable" 0 "org.freedesktop.DBus.ObjectManager" 0 "org.freedesktop.DBus.Properties" 0 "org.storage.stratis1.Manager" 3 "ErrorValues" a(sq) 17 "OK" 0 "ERROR" 1 "ALREADY_EXISTS" 2 "BAD_PARAM" 3 "BUSY" 4 "CACHE_NOTFOUND" 5 "DEV_NOTFOUND" 6 "FILESYSTEM_NOTFOUND" 7 "IO_ERROR" 8 "LIST_FAILURE" 9 "INTERNAL_ERROR" 10 "NIX_ERROR" 11 "NO_POOLS" 12 "NOTFOUND" 13 "NULL" 14 "NULL_NAME" 15 "POOL_NOTFOUND" 16 "RedundancyValues" a(sq) 1 "NONE" 0 "Version" s "0.1.0"
[mulhern@dhcp-25-209 stratisd]$ busctl --user call org.storage.stratis1 /org/storage/stratis1 org.storage.stratis1.Manager CreatePool "s(bq)bas" "deadpool" false 0 false 1 /dev/sdl
(oas)qs "/org/storage/stratis1/1" 1 "/dev/sdl"0 "Ok"
[mulhern@dhcp-25-209 stratisd]$ busctl --user call org.storage.stratis1 /org/storage/stratis1 org.freedesktop.DBus.ObjectManager GetManagedObjects
no name for pool with object path /org/storage/stratis1
[mulhern@dhcp-25-209 stratisd]$ busctl --user get-property org.storage.stratis1 /org/storage/stratis1/1 org.storage.stratis1.pool Uuid
s "2c19bce95dbf4b40b10212e408629af0

[diwic]

Thanks, now I get it. I just pushed a commit to master, could you see if it fixes the issue?

[mulkieran]

Confirmed, thanks!