On November 16, 2021 10:31 AM, Jeff King wrote: > On Tue, Nov 16, 2021 at 03:35:41AM +0000, brian m. carlson wrote: > > > The order of options is also important here. On systems with > > arc4random, which is most of the BSDs, we use that, since, except on > > MirBSD, it uses ChaCha20, which is extremely fast, and sits entirely > > in userspace, avoiding a system call. We then prefer getrandom over > > getentropy, because the former has been available longer on Linux, and > > finally, if none of those are available, we use /dev/urandom, because > > most Unix-like operating systems provide that API. We prefer options > > that don't involve device files when possible because those work in > > some restricted environments where device files may not be available. > > I wonder if we'll need a low-quality fallback for older systems which don't > even have /dev/urandom. Because it's going to be used in such a core part of > the system (tempfiles), this basically becomes a hard requirement for using > Git at all. > > I can't say I'm excited in general to be introducing a dependency like this, just > because of the portability headaches. But it may be the least bad thing > (especially if we can fall back to the existing behavior). > One alternative would be to build on top of the system mkstemp(), which > makes it libc's problem. I'm not sure if we'd run into problems there, though. None of /dev/urandom, /dev/random, or mkstemp are available on some platforms, including NonStop. This is not a good dependency to add. One variant PRNGD is used in ia64 OpenSSL, while the CPU random generator in hardware is used on x86. I cannot get behind this at all. Libc is also not used in or available to our port. I am very worried about this direction. -Randall
