Function hdk::prelude::allocation::write_bytes

pub fn write_bytes(slice: &[u8]) -> u32

Attempt to write a slice of bytes into a length prefixed allocation.

This is identical to the following:

• host has some slice of bytes
• host calls __allocate with the slice length
• guest returns GuestPtr to the host
• host writes a length prefix and the slice bytes into the guest at GuestPtr location
• host hands the GuestPtr back to the guest

In this case everything happens within the guest and a GuestPtr is returned if successful.

This also leaks the written bytes, exactly like the above process.

This facilitates the guest handing a GuestPtr back to the host as the return value of guest functions so that the host can read the output of guest logic from a length-prefixed pointer.

A good host will call __deallocate with the GuestPtr produced here once it has read the bytes out of the guest, otherwise the bytes will be permanently leaked for the lifetime of the guest.