Struct PassFatPointerAndReadWrite

pub struct PassFatPointerAndReadWrite<T>(/* private fields */);

Pass a value into the host by a fat pointer, writing it back after the host call ends.

This casts the value into a &mut [u8] and passes a pointer to that byte blob and its length to the host. Then the host reads that blob and converts it into an owned type and passes it as a mutable reference to the host function. After the host function finishes the byte blob is written back into the guest memory.

Raw FFI type: u64 (a fat pointer; upper 32 bits is the size, lower 32 bits is the pointer)

Trait Implementations

impl<'a> FromFFIValue<'a> for PassFatPointerAndReadWrite<&'a mut [u8]>

type Owned = Vec<u8>

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> RIType for PassFatPointerAndReadWrite<T>

type FFIType = u64

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.