Is Golang crypto/rand thread safe?

Question

The source of math/rand.Rand states Read is not thread safe (when sharing a source). What about crypto/rand? The source states it uses getrandom(2) or /dev/urandom, but it is unclear what happens with concurrent calls.

Update: comments have helped clarify the distinction

crypto/rand.Reader.Read(b []byte)
crypto/rand.Read(b []byte)

To be a thread safe:

1. Will it panic when Read is called concurrently?
2. Will it keep the random sequence when called concurrently? Or can duplicates be given to concurrent callers?

Answer 1

1. rand.Reader from crypto/rand must be safe for concurrent access, because it is defined as "a global, shared instance of a cryptographically secure random number generator". There would be no way to synchronize its use between packages.
2. rand.Read from crypto/rand is safe because the rand.Reader is safe, and it does not access any other shared state.