Date:	Sun, 3 May 1998 17:38:17 +0300 (IDT)
From:	Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To:	"Salvador Eduardo Tropea (SET)" <salvador AT inti DOT gov DOT ar>
cc:	djgpp AT delorie DOT com
Subject:	Re: fstat and stat in a Novell disk (fstat have a flaw)
In-Reply-To:	<m0yUaE7-000S3YC@inti.gov.ar>
Message-ID:	<Pine.SUN.3.91.980503173701.19706I-100000@is>
MIME-Version:	1.0

On Wed, 29 Apr 1998, Salvador Eduardo Tropea (SET) wrote:

> I have some questions about fstat/stat. I found they work VERY
> different.

They are different, indeed.  Neither DOS nor Windows don't let you
know the full pathname of a file given the handle on which it is open,
so there's no way these two could do exactly the same.

I wouldn't use the words ``VERY different'', though.  Is there any
other difference in the results except the write bit?  If so, please
tell what other discrepancies did you see.

> But when using fstat it
> uses some SFT(?) table, I don't know what's that, anyways, Novell
> doesn't support it and hence libc just gives a general description,
> that means: the file have read access because DOS ever have it, but
> no write access just in case.

This is documented behavior, see "info libc alpha fstat", under
``Implementation Notes''.  You just cannot get at the file attributes
under Novell on plain DOS, period.

>  That's bad for my editor because it detects the files as
> read-only. I'm using stat because I want to get the program working
> on UNIX.

If you use `stat', it should report the file attributes under Novell
as well; only `fstat' has this problem.

If you cannot use `stat', a work-around would be to just try writing
to the file, and if you get EACCES, treat it as if the file were not
writable by the user.

> Now the question is: why fstat can't use the file attributes to
> solve it?

Why don't you ask how does `fstat' succeed to report file attributes at 
all? 

There is no DOS call which allows to access file attributes given a
handle alone, and as I said above, you can't get the file name by its
handle.  The DJGPP implementation of `fstat' goes out of its way--and
succeeds--to compute them correctly under DOS and Windows 9X, but it
fails under Novell versions which bypass DOS file-oriented data
structures.  You should look at the source code for `fstat' some day,
to see how hard it is to report Unix-compatible results.

Windows 9X adds a function to report file info given a handle, so on
Windows `fstat' works correctly (you need the latest `fstat' from Tom
Demmer's site or from the latest v2.02 alpha, to have this feature, as
it was only introduced lately).

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