md5: Create md5sum, etc compatible programs

[imp]

Summary

On Linux, there's a similar set of programs to ours, but that end in the
letters 'sum'. These act basically like FreeBSD versions run with the -r
option. Add code so that when the program ends in 'sum' you get the
linux -r behavior. This is enough to make most things that use sha*sum
work correctly (the -c / --check options, as well as the long args
are not implemented).

Relnotes: yes
Sponsored by: Netflix

Test Plan

Note: I've not implemented all the flags of *sum, but this is enough to make qemu's test suite
happier with FreeBSD and it's not the first time I've hit this issue.

[sef]

lgtm.

[darius-dons.net.au]

I think there should be some updates to the man page to note the links and that they are for (limited) Linux compatibility.

sbin/md5/md5.c

188

A comment about why this is done would be good.

[imp]

man page update and comment

[allanjude]

Reviewed By: allanjude

[bcr]

Manpages is also fine with the change. Thanks!

[kp]

sbin/md5/md5.c

192

s/proide/provide/

[0mp]

Does it mean that FreeBSD *sum versions of those utilities are going to support all the existing FreeBSD flags? Shouldn't we restrict the flags of the *sum utilities to only those that provide the same functionality both on FreeBSD and on GNU?

[emaste]

Shouldn't we restrict the flags of the *sum utilities to only those that provide the same functionality both on FreeBSD and on GNU?

Not a bad idea, we can introduce *sum flags intentionally, as necessary.

[imp]

In D30309#680792, @emaste wrote:

Shouldn't we restrict the flags of the *sum utilities to only those that provide the same functionality both on FreeBSD and on GNU?

Not a bad idea, we can introduce *sum flags intentionally, as necessary.

I think the best bet is to flag the -c use in this mode because they are different. We could also accept-b and -t as nops too easily enough. Any extensions from there, though, I don't think we should prohibit.

[imp]

Better compatibility with gnu versions from coreutils. Note this
in man page.

[imp]

Tweak wording, and provide sha1sum for consistency.

[imp]

sbin/md5/md5.c

376

this is a trivial trailing whitespace thing emacs decided to fix... Normally, I'd split it out, but it's trivial enough to be flexible on the style / substance division we normally do)

[sef]

sbin/md5/md5.1

104

Traditional English convention is "-sum" not "*sum". Not worth changing unless a) you agree, and b) have other changes to make.