pub fn get_return_data() -> Option<ReturnData>Expand description
Retrieve return data from the most recent CPI call.
Returns None if no return data was set (length == 0).
The 1 KiB buffer is not zero-filled before the syscall, the syscall
initializes exactly the reported prefix, and None is returned before any
read when the length is 0. This is the bug class behind Quasar #238/#234
(an assume_init over a buffer the syscall never wrote, exposing
uninitialized stack bytes as return data); Hopper’s shape is immune
because uninitialized bytes can never escape: empty return data (including
the off-chain path, where len stays 0) short-circuits to None, and
every accessor reads only the syscall-initialized len-byte prefix.