Function librados_sys::rados_read_op_exec_user_buf

pub unsafe extern "C" fn rados_read_op_exec_user_buf(
    read_op: rados_read_op_t, 
    cls: *const c_char, 
    method: *const c_char, 
    in_buf: *const c_char, 
    in_len: size_t, 
    out_buf: *mut c_char, 
    out_len: size_t, 
    used_len: *mut size_t, 
    prval: *mut c_int
)