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From: "Randy Brukardt" <randy@rrsoftware.com>
Newsgroups: comp.lang.ada
Subject: Re: if file exist
Date: Fri, 27 Sep 2002 13:43:41 -0500
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Date: 2002-09-27T13:43:41-05:00
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steve_H wrote in message
<8db3d6c8.0209270247.5bf07ae5@posting.google.com>...
>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.


That would be a terrible breach of security. Simply that fact that
something exists can be used as an attack point or a way to transmit
information. To a process that doesn't have permission to a directory,
no information whatsover about the file should be available.

The point is that "If_Exist" is meaningless by itself. Its meaning
depends on permissions and capabilities and probably other stuff that
couldn't practically be standardized.

Of course, if everyone implemented Ada.Directories, you could use that
and figure out whatever interpretation you'd like.

          Randy.