Check whether "getrandom" exists

[glassez]

Under some Linux environments (e.g. Termux) "getrandom" may not actually exist.

[Chocobo1]

What is the actual problem with Termux?
Is this system header not present?

Under some Linux environments (e.g. Termux) "getrandom" may not actually exist.

randomlayer_linux.cpp have fallback path, is it not working?

qBittorrent/src/base/utils/randomlayer_linux.cpp

Lines 48 to 57 in cade7c2

	if (unsigned char buf = 0; ::getrandom(&buf, sizeof(buf), 0) < 0)
	{
	if (errno == ENOSYS)
	{
	// underlying kernel does not implement this system call
	// fallback to `urandom`
	m_randDev = fopen("/dev/urandom", "rb");
	if (!m_randDev)
	qFatal("Failed to open /dev/urandom. Reason: \"%s\". Error code: %d.", std::strerror(errno), errno);
	}

I guess the function simply doesn't exist...

[glassez]

I guess the function simply doesn't exist...

Yes. The sys/random.h header exists but it defines getrandom function depending on Android API version which is not satisfied by Termux (Termux is built for a lower API version).