Reference .2.html

Hi,

Looks to me it must be thread-safe, but I could not find any official documentation talks about this.

Is getrandom() in sys/random.h always and necessary thread-safe?

Thanks.

Reference https://man7./linux/man-pages/man2/getrandom.2.html

Hi,

Looks to me it must be thread-safe, but I could not find any official documentation talks about this.

Is getrandom() in sys/random.h always and necessary thread-safe?

Thanks.

• c++
• linux

• 2 The Linux API is actually in C not C++. If you do use C++ (since you tagged it) - have a look at How do I generate thread-safe uniform random numbers?. – wohlstad Commented Mar 22 at 12:30

1 Answer 1

It is generally safe to assume that system calls are thread-safe. See the following Stack Overflow question for further information:

How can I know whether a Linux syscall is thread safe?

The function getrandom is a system call, because it is in section 2 of the Linux manual pages, which has the title "System Calls Manual".

Even if it were not a system call, but rather a library function, since getrandom does nothing else than read from /dev/urandom or /dev/random, it would probably be safe to assume that it were thread-safe.

Note however that the standard library function rand (which is not a system call) is not thread-safe, because it reads from and writes to memory that is shared by all threads, and this memory is not protected by a mutex.