pub unsafe trait JniType {
// Required method
fn static_with_jni_type<R>(callback: impl FnOnce(&str) -> R) -> R;
}Expand description
JNI bindings rely on this type being accurate.
unsafe: static_with_jni_type must pass a string terminated by ‘\0’. Failing to do so is a soundness bug, as the string is passed directly to JNI as a raw pointer! Additionally, passing the wrong type may be a soundness bug as although the Android JVM will simply panic and abort, I’ve no idea if that’s a guarantee or not.
Why the awkward callback style instead of returning &'static str? Arrays of arrays may need to dynamically
construct their type strings, which would need to leak. Worse, we can’t easily intern those strings via
lazy_static without running into:
error[E0401]: can't use generic parameters from outer functionRequired Methods§
fn static_with_jni_type<R>(callback: impl FnOnce(&str) -> R) -> R
Dyn Compatibility§
This trait is not dyn compatible.
In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.