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Path: utzoo!watmath!clyde!rutgers!ames!oliveb!rap
From: rap@oliveb.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Re: Major bug in all(?) versions of MS-DOS.
Message-ID: <495@oliveb.UUCP>
Date: Sat, 7-Feb-87 15:23:34 EST
Article-I.D.: oliveb.495
Posted: Sat Feb  7 15:23:34 1987
Date-Received: Sun, 8-Feb-87 07:47:36 EST
References: <4274@utah-cs.UUCP>
Reply-To: rap@olivej.UUCP (Robert A. Pease)
Organization: Olivetti ATC; Cupertino, Ca
Lines: 33
Keywords: bug
Summary: No bug, just buffered.


In article <4274@utah-cs.UUCP> b-davis@utah-cs.UUCP (Brad Davis) writes:
>; POINT A
|; If these three lines are included then all works well.
|;	mov	bx, fd1
|;	mov	ah, 3eh
|;	int	21h
|	; open the file a second time
|	; fd2 = open("xxx", O_RDWR | O_BINARY, 0);
|	mov	dx, offset xxx
|	mov	al, 2
|	mov	ah, 3dh
|	int	21h
|	mov	fd2, ax
|; POINT B
|; If these three lines are included then the read still fails.
|;	mov	bx, fd1
|;	mov	ah, 3eh
|;	int	21h
|	; read the data from the second file

Not a bug.  You just didn't account  for  DOS  buffers.  The
file  may be writen to at POINT A, but the disk isn't.  When
you issue the function 3eh call at POINT A the  buffers  are
flushed  and  the file closed.  When the buffers are flushed
is when the disk gets writen.

I think that if you look at your example now you can see why
POINT A behaves differently from POINT B.
-- 

					Robert A. Pease
{hplabs|fortune|idi|ihnp4|tolerant|allegra|glacier|olhqma}!oliveb!olivej!rap