Function presser::readback_slice_from_ffi

pub unsafe fn readback_slice_from_ffi<'a, T, S, F>(
    slab: &'a mut S,
    fill_slab: F
) -> Result<&'a [T], Error>where
    S: Slab + ?Sized,
    F: FnOnce(*mut c_void, usize) -> usize,

Helper to read back data from an ffi function which expects a pointer into which it will write a slice (in C language, an array) of Ts.

fill_slab is a function which takes as parameters first an aligned (for T) *mut c_void and second the number of bytes left in slab available for writing. It must then write a slice of Ts into the given pointer and return the length, in units of T, of the slice it wrote.

slab will be used as the backing data to write the slice of Ts into. The *mut c_void pointer given to the function will be as close to the beginning of slab as possible while upholding the alignment requirements of T.

Safety

You must during the execution of fill_slab fully-initialize a valid* slice of T beginning at the given pointer and with length greater than or equal to the length you return from that function.

* Validity is a complex topic not to be taken lightly. See this rust reference page for more details.