Function sp_io::storage::read

pub fn read(key: &[u8], value_out: &mut [u8], value_offset: u32) -> Option<u32>

Get key from storage, placing the value into value_out and return the number of bytes that the entry in storage has beyond the offset or None if the storage entry doesn't exist at all. If value_out length is smaller than the returned length, only value_out length bytes are copied into value_out.