Function state_entry_read 

pub unsafe extern "C" fn state_entry_read(
    entry: u64,
    start: *mut u8,
    length: u32,
    offset: u32,
) -> u32

Read a part of the entry. The arguments are entry … entry id returned by state_iterator_next or state_create_entry start … where to write in Wasm memory length … length of the data to read offset … where to start reading in the entry The return value is

• u32::MAX if the entry does not exist (has been invalidated, or never existed). In this case no data is written.
• amount of data that was read. This is never more than length.