Support FreeBSD, NetBSD, OpenBSD, and Solaris using /dev/urandom.

[briansmith]

No description provided.

[josephlr]

For OpenBSD, this is fine. /dev/random and /dev/urandom are the same, and aren't dumb.

For NetBSD, this is fine. NetBSD has nearly identical interfaces as Linux (including the #558).

For FreeBSD, we should use /dev/random. /dev/urandom isn't mentioned in the man pages, and /dev/random doesn't have the weird Linux problems, see the docs. EDIT: fixed an incorrect reference to FreeBSD docs.

For Solaris, it's really not clear which to use, the docs are bad, mentioning "higher-quality" and "lower-quality" randomness without explaining what those terms mean. The getrandom crate falls back to using /dev/random (see this note). Regardless of which is used, the data needs to be read in chunks, as there are hard limits to how many bytes can be read(2) at a time:

• 1024 for /dev/random
• 128*1024 for /dev/urandom

Some of these platforms (OpenBSD, FreeBSD, Solaris) have APIs like Linux's getrandom(2) that allow you to get randomness without holding on to a file descriptor. But that requires a bunch of target specific code.

An alternative would be to just use the getrandom crate.

[briansmith]

For FreeBSD, we should use /dev/random. /dev/urandom isn't mentioned in the man pages, and /dev/random doesn't have the weird Linux problems, see the docs. EDIT: fixed an incorrect reference to FreeBSD docs.

It's unfortunate that they never documented /dev/urandom. However, I verified /dev/urandom exists in every currently-supported (by freebsd.org) FreeBSD release.

[josephlr]

For FreeBSD, we should use /dev/random. /dev/urandom isn't mentioned in the man pages, and /dev/random doesn't have the weird Linux problems, see the docs. EDIT: fixed an incorrect reference to FreeBSD docs.

It's unfortunate that they never documented /dev/urandom. However, I verified /dev/urandom exists in every currently-supported (by freebsd.org) FreeBSD release.

So I found something weird, FreeBSD 4.11 does document /dev/urandom, but they stopped documenting it in 5.0, so using /dev/urandom is probably fine. The Solaris support could just be removed.

[briansmith]

For Solaris, it's really not clear which to use

My goal here is to make Solaris work again as well as it did in 0.14.6 (slightly better, in fact). I filed #876 to track improving Solaris support.

The Solaris support could just be removed.

It's now required by some commercial users of ring.

[josephlr]

It's now required by some commercial users of ring.

Sounds good, makes sense to me.