Fixing valid-id in regex

[rajasec]

Fixes #635
Also removed _ ,as _ is part of \w
Signed-off-by: rajasec rajasec79@gmail.com

[cyphar]

FWIW, I'm fairly sure most regex implementations consider [.] to mean the literal . character (not "any" character, since [.] would be meaningless otherwise).

[rajasec]

But without this change, "." is not accepted as valid ID by runc. So I've added part of idregex so that dot is also accepted.

[cyphar]

Sorry, what I was saying is that you can write it as [\w-.] and it should still work. It's just a nit. :P

[rajasec]

@cyphar
Agree. what you mention will work. Since it gave panic for [\w_-.], so I've added the back tick before the dot operator to be safe.
Let me know whether you are ok with the current change.

[rajasec]

@crosbymichael @mrunalp @hqhq
Let me know your comments.

[hqhq]

LGTM

[mrunalp]

LGTM

[ip1981]

Honestly, this restriction should not exist. My deployment tools allow some odd ids, my filesystem allows odd file names, and then comes an intermediate layer (runc) telling they cannot be together. Just let it crash, it's out of scope. At least add a comment about why you think this restriction is needed. So nobody will ask again.

[wking]

On Fri, Mar 18, 2016 at 10:51:59AM -0700, Igor Pashev wrote:

Honestly, this restriction should not exist.

Related discussion in [1,2]. Since this seems like a spec issue
that's more generic than runC, maybe move the discussion into the
mailing list thread 1?

 Subject: [PATCH] runtime: Document container ID charset and uniqueness domain
 Date: Thu, 3 Sep 2015 15:07:33 -0700
 Message-ID: <c08ed73c894899e5ff6c312ecd22de7b4b296e79.1441317770.git.wking@tremily.us>

 Subject: Update cgroupsPath to cgroupName and clarify the
   semantics around that.