[Acl-devel] acl_{set,get}_file nofollow variants

[Knister, Aaron S. (GSFC-606.2)[COMPUTER SCIENCE CORP]]

Dear ACL devs,

As part of a mass user id number change this past year I wrote some tools to deal with updating ACLs on our half billion files/directories. In writing the tool I was trying to be security conscious so I wanted a way to be able to get and set ACLs on files without worrying about race conditions between a stat and setxattr/getxattr should a regular file suddenly become a symlink during an acl set/get operation. 

I took a similar approach to what was done with acl_extended_file and acl_extended_file_nofollow and moved acl_file_{get,set} to __acl_file_{get,set} and added the ability to pass in the appropriate stat/*xattr functions. 

Here's are the changes. I'm hoping they could get merged in case they're useful to others:

https://github.com/aaronknister/acl/compare/nofollow

I'm happy to e-mail a patch via git if need be but I've not done it in a while so it may take me a little while.

-Aaron 

ps libacl worked great for me! Thanks for a great library.