Struct PassPointerAndWrite

pub struct PassPointerAndWrite<T, const N: usize>(/* private fields */);

Pass a pointer into the host and write to it after the host call ends.

This casts a given type into &mut [u8] using AsMut<[u8]> and passes a pointer to that byte slice into the host. The host doesn’t read from this and instead creates a default instance of type T and passes it as a &mut T into the host function implementation. After the host function finishes this value is then cast into a &[u8] using AsRef<[u8]> and written back into the guest memory.

Raw FFI type: u32 (a pointer)

Trait Implementations

impl<'a, T, const N: usize> FromFFIValue<'a> for PassPointerAndWrite<&'a mut T, N>

where T: Default + AsRef<[u8]>,

type Owned = T

The owned inner type.

fn from_ffi_value( _context: &mut dyn FunctionContext, _arg: Self::FFIType, ) -> Result<Self::Owned>

Creates Self::Owned from the given arg received through the FFI boundary from the runtime.

fn take_from_owned(owned: &'a mut Self::Owned) -> Self::Inner

Creates Self::Inner from an owned value.

fn write_back_into_runtime( value: Self::Owned, context: &mut dyn FunctionContext, arg: Self::FFIType, ) -> Result<()>

Write back a modified value back into the runtime’s memory.

impl<T, const N: usize> RIType for PassPointerAndWrite<T, N>

type FFIType = u32

The raw FFI type that is used to pass Self through the host <-> runtime boundary.

type Inner = T

The inner type without any serialization strategy wrapper.