access permissions in 1003.1

[Ed Gould]

Submitted-by: ed at mtxinu.COM (Ed Gould)

>The problem, phrased in 1003.1's terms, is what happens if i am both
>the owner and group of a file with mode 040; can I read it?

The traditional UNIX implementation of file permissions has
been

	if owned by user
		check owner bits
	else if owned by user's group
		check group bits
	else
		check other bits

Hence, if one owns a file *only* the owner bits matter.  The group
bits apply only to non-owners in the group; the other bits apply
only to non-owner non-group.  I don't know what 1003.1 says, though.
Given its reliance on traditional UNIX, this is what I'd expect it
to say.

The other reasonable interpretation I can imagine is

	if (owned by user and owner bits allow access) or
	   (owned by user's group and group bits allow access) or
	   (other bits allow access)
		grant access
	else
		deny access

I'd bet small amounts of money that this latter interpretation
doesn't conform to 1003.1.

-- 
Ed Gould			No longer formally affiliated with,
ed at mtxinu.COM			and certainly not speaking for, mt Xinu.

"I'll fight them as a woman, not a lady.  I'll fight them as an engineer."


Volume-Number: Volume 23, Number 83