metadata changed event key must be optional

[saivert]

changed event is emitted with key == NULL when a metadata item is removed.

see https://gitlab.freedesktop.org/pipewire/wireplumber/-/blob/ca58c68ef988e57f5bec232fe6c9ab86d5f0ea19/lib/wp/metadata.c#L218

Though I'm moving to using closure_local macro which makes me get at the event arguments directly instead of via GValue.

let changed_closure = closure_local!(@watch widget =>
                        move |_obj: &wp::pw::Metadata, id: u32, key: Option<String>, _type: Option<String>, _value: Option<String>| {
                        let key = key.unwrap_or_default();
                        if id == boundid && key.contains("target.") {
                            wp::log::info!("metadata changed handler id: {boundid} {key:?} {_value:?}!");
                            widget.update_output_device_dropdown();
                        }
                    });
                    metadata.connect_closure("changed", false, changed_closure);

[arcnmx]

This sounds like a duplicate of #30, was it not fixed by 95c55499881dea199a1c62f755f35b9e7c1b2fb0? What code reproduces the issue?

[saivert]

Yes, it was partly fixed then but key also has to be Optional.

Not sure why you need a reproducer but this is enough:

metadata.connect_changed(|obj, subject, key, type_, value| {
                        wp::log::info!("metadata changed handler id: {subject} {key:?} {type_:?} {value:?}!");
                    });

Then remove the metadata using command line: pw-metadata -d 59

And you have a crash:

thread 'main' panicked at 'assertion failed: !ptr.is_null()', /home/saivert/Projects/pwvucontrol/builddir/cargo-home/registry/src/index.crates.io-6f17d22bba15001f/glib-0.18.1/src/gstring.rs:1973:9
stack backtrace:
   0: rust_begin_unwind
   1: core::panicking::panic_fmt
   2: core::panicking::panic
   3: <glib::gstring::GString as glib::translate::FromGlibPtrBorrow<*const u8>>::from_glib_borrow
             at /home/saivert/Projects/pwvucontrol/builddir/cargo-home/registry/src/index.crates.io-6f17d22bba15001f/glib-0.18.1/src/gstring.rs:1973:9
   4: glib::translate::from_glib_borrow
             at /home/saivert/Projects/pwvucontrol/builddir/cargo-home/registry/src/index.crates.io-6f17d22bba15001f/glib-0.18.1/src/translate.rs:1640:5
   5: <glib::gstring::GString as glib::translate::FromGlibPtrBorrow<*mut i8>>::from_glib_borrow
             at /home/saivert/Projects/pwvucontrol/builddir/cargo-home/registry/src/index.crates.io-6f17d22bba15001f/glib-0.18.1/src/gstring.rs:2005:9
   6: wireplumber::auto::metadata::MetadataExt::connect_changed::changed_trampoline
             at /home/saivert/Projects/pwvucontrol/builddir/cargo-home/git/checkouts/wireplumber.rs-cb0425781db64edb/341b0c4/src/auto/metadata.rs:74:76
   7: <unknown>
   8: <unknown>
   9: ffi_call
  10: g_cclosure_marshal_generic
  11: g_closure_invoke
  12: <unknown>
  13: g_signal_emit_valist
  14: g_signal_emit
  15: <unknown>
  16: <unknown>
  17: <unknown>
  18: <unknown>
  19: <unknown>
  20: <unknown>
  21: g_main_context_dispatch
  22: <unknown>
  23: g_main_context_iteration
  24: g_application_run
  25: gio::application::ApplicationExtManual::run_with_args
             at /home/saivert/Projects/pwvucontrol/builddir/cargo-home/registry/src/index.crates.io-6f17d22bba15001f/gio-0.18.1/src/application.rs:29:13
  26: gio::application::ApplicationExtManual::run
             at /home/saivert/Projects/pwvucontrol/builddir/cargo-home/registry/src/index.crates.io-6f17d22bba15001f/gio-0.18.1/src/application.rs:22:9
  27: pwvucontrol::main
             at /home/saivert/Projects/pwvucontrol/src/main.rs:118:5
  28: core::ops::function::FnOnce::call_once
             at /builddir/build/BUILD/rustc-1.72.0-src/library/core/src/ops/function.rs:250:5
note: Some details are omitted, run with `RUST_BACKTRACE=full` for a verbose backtrace.

[arcnmx]

Gotcha, p0 was missed in that fix, thanks for the clarification!