Implement VmIo for smart pointers to VmIo

[tatetian]

Pointers to VmIo, e.g., &Vmar, Box<Mmio>, and Arc<Vmo>, should also be considered as VmIo. This can be achieved by providing the following blanket implementations for Vmio trait.

// Need to import inherit_methods_macro crate from Occlum.
// https://github.com/occlum/occlum/tree/1.0.0-preview/src/libos/crates/inherit-methods-macro
use inherit_methods_macro::inherit_methods;

#[inherit_methods(from = "(**self)")]
impl<T: Vmio> Vmio for &T {
    fn read_bytes(&self, offset: usize, buf: &mut [u8]) -> Result<()>;
    fn read_val<T: Pod>(&self, offset: usize) -> Result<T>;
    fn read_slice<T: Pod>(&self, offset: usize, slice: &mut [T]) -> Result<()>;
    fn write_bytes(&self, offset: usize, buf: &[u8]) -> Result<()>;
    fn write_val<T: Pod>(&self, offset: usize, new_val: &T) -> Result<()>;
    fn write_slice<T: Pod>(&self, offset: usize, slice: &[T]) -> Result<()>;
}

// Need to add the following blanket implementations for Vmio
#[inherit_methods(from = "(**self)")]
impl<T: Vmio> Vmio for &mut T {
    fn read_bytes(&self, offset: usize, buf: &mut [u8]) -> Result<()>;
    fn read_val<T: Pod>(&self, offset: usize) -> Result<T>;
    fn read_slice<T: Pod>(&self, offset: usize, slice: &mut [T]) -> Result<()>;
    fn write_bytes(&self, offset: usize, buf: &[u8]) -> Result<()>;
    fn write_val<T: Pod>(&self, offset: usize, new_val: &T) -> Result<()>;
    fn write_slice<T: Pod>(&self, offset: usize, slice: &[T]) -> Result<()>;
}

// Need to add the following blanket implementations for Vmio
#[inherit_methods(from = "(**self)")]
impl<T: Vmio> Vmio for Box<T> {
    fn read_bytes(&self, offset: usize, buf: &mut [u8]) -> Result<()>;
    fn read_val<T: Pod>(&self, offset: usize) -> Result<T>;
    fn read_slice<T: Pod>(&self, offset: usize, slice: &mut [T]) -> Result<()>;
    fn write_bytes(&self, offset: usize, buf: &[u8]) -> Result<()>;
    fn write_val<T: Pod>(&self, offset: usize, new_val: &T) -> Result<()>;
    fn write_slice<T: Pod>(&self, offset: usize, slice: &[T]) -> Result<()>;
}

// Need to add the following blanket implementations for Vmio
#[inherit_methods(from = "(**self)")]
impl<T: Vmio> Vmio for Arc<T> {
    fn read_bytes(&self, offset: usize, buf: &mut [u8]) -> Result<()>;
    fn read_val<T: Pod>(&self, offset: usize) -> Result<T>;
    fn read_slice<T: Pod>(&self, offset: usize, slice: &mut [T]) -> Result<()>;
    fn write_bytes(&self, offset: usize, buf: &[u8]) -> Result<()>;
    fn write_val<T: Pod>(&self, offset: usize, new_val: &T) -> Result<()>;
    fn write_slice<T: Pod>(&self, offset: usize, slice: &[T]) -> Result<()>;
}

[tatetian]

Done