Merge "topshim: don't pass NULL to slice::from_raw_parts" into main

use std::mem;

use std::os::fd::RawFd;

use std::os::raw::c_char;

use std::ptr::NonNull;

use std::sync::{Arc, Mutex};

use std::vec::Vec;

use topshim_macros::{cb_variant, gen_cxx_extern_trivial};

// TODO(abps) - Check that sizes are correct when given a BtProperty

impl From<bindings::bt_property_t> for BluetoothProperty {

    fn from(prop: bindings::bt_property_t) -> Self {

        let slice: &[u8] =

            unsafe { std::slice::from_raw_parts(prop.val as *mut u8, prop.len as usize) };

        // Property values may be null, which isn't valid to pass for `slice::from_raw_parts`.

        // Choose a dangling pointer in that case.

        let prop_val_ptr =

            NonNull::new(prop.val as *mut u8).unwrap_or(NonNull::dangling()).as_ptr();

        let len = prop.len as usize;

        let slice: &[u8] = unsafe { std::slice::from_raw_parts(prop_val_ptr, len) };

        match BtPropertyType::from(prop.type_) {

            BtPropertyType::BdName => BluetoothProperty::BdName(ascii_to_string(slice, len)),