From mboxrd@z Thu Jan  1 00:00:00 1970
From: erik quanstrom <quanstro@labs.coraid.com>
Date: Fri, 26 Feb 2010 12:43:33 -0500
To: 9fans@9fans.net
Message-ID: <329a0a1c22aba5018223cdfb2fe21f03@coraid.com>
In-Reply-To: <7b956f03980157ec2a6357aaa14eb60f@quintile.net>
References: <7b956f03980157ec2a6357aaa14eb60f@quintile.net>
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Subject: Re: [9fans] exec permission on plan9
Topicbox-Message-UUID: dc98e364-ead5-11e9-9d60-3106f5b1d025

> It appears to me (though my code may be buggy) that
> the file server is expected to enforce the exec bit
> in the file's modes when a file is opened with OEXEC.

yes.

> I would have expected rc(1) to have checked the mode and
> not to have tried to exec() the file if the exec bit in the
> file's mode is not set.

rc does check, but the check is not bulletproof:

from plan9.c:/^Executable

	ret = ((statbuf->mode&0111)!=0 && (statbuf->mode&DMDIR)==0);

rc will try to execute a file for which the owner
has execute permission, but you are not the owner.
byron's rc goes to great pains to get this right, but
in plan 9 it's not really possible since there is no
way to get a user's groups.  since this is a property
of the fileserver, and by design you're not supposed
to know those things.  :-)

- erik