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From: Mark Biggar <mark.a.biggar@attbi.com>
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Subject: Re: if file exist
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steve_H wrote:
> Robert A Duff <bobduff@shell01.TheWorld.com> wrote in message news:<wccadm41jqs.fsf@shell01.TheWorld.com>... 
>>I don't agree that "a general solution is not possible".
>>A File_Exists return Boolean function makes perfect sense.
>>Of course it returns False if the file is invisible to the 
>>current process (because it "exists" in an inaccessible directory).
>>To *this* process, that file does not exist.
> But the above is not logical. If your function return FALSE, then one
> does not know if this means the file actually does not exist, or that 
> the function was not able to determine if it exist or not becuase of 
> permission issues.  The user might want to know this.

No, from a computer security point of view, this is exactly what is
wanted.  A user should see absolutely no difference between "file does
not exist" and "you don't have permission to see the file".  Otherwise,
you have introduced a covert information channel.

-- 
Mark Biggar
mark.a.biggar@attbi.com