df . (was: Re: It works everywhere else, but not on AIX)

[Melinda Shore]

In article <3783 at d75.UUCP> woan at cactus.org writes:
>In article <1991Apr16.210447.28136 at ibmpa.awdpa.ibm.com> jsalter at slo.awdpa.ibm.com (Jim Salter) writes:
>>Sure enough, if the access mode for the directory doesn't have the user's
>>executable bit on, df . doesn't work.  A defect has been opened.
>Are you positive that this is a defect? 

This is a bug, maybe.  In Unix filesystem semantics, if the permissions
on a directory are set up so that the relevant (to the user opening the
directory) read bits are on but the execute bits are off, the user 
should be able to read the directory but not any files in the directory.
It also means that the user should be able to stat(2) the directory.
However, it means that the user should not be able to cd into the 
directory.
Now, if the permissions look something like
	drwxr--r-- 6 shore staff 	...
shore will be able to access files in the directory, but nobody else
(other than root) will.  The only way that I can think of off the top
of my head that doing "df ." should fail for a legitimate reason
would be if df is setuid someone other than root, and the directory
permissions were as peculiar as those listed above.
-- 
                    Software longa, hardware brevis
Melinda Shore - Cornell Information Technologies - shore at theory.tn.cornell.edu