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Path: utzoo!attcan!uunet!lll-winken!lll-lcc!ames!pasteur!agate!violet.berkeley.edu!dean
From: dean@violet.berkeley.edu (Dean Pentcheff)
Newsgroups: comp.unix.xenix,comp.unix.questions,comp.unix.wizards
Subject: Re: Curses Problem
Summary: overwrite is broken on too many systems to depend on it.
Keywords: curses newwin problem overwrite bug
Message-ID: <18289@agate.BERKELEY.EDU>
Date: 14 Dec 88 07:51:17 GMT
References: <263@madnix.UUCP>
Sender: usenet@agate.BERKELEY.EDU
Followup-To: comp.unix.xenix,comp.unix.questions,comp.unix.wizards
Organization: University of California, Berkeley   Department of Zoology
Lines: 31

In article <263@madnix.UUCP> ray@madnix.UUCP (Ray P. Hill) writes:
>	Why does the following curses code sample produce a different output
>	on UNIX systems?
>	Some machines produce and map both windows while others map both
>	windows to the same location on the screen. Our VAX, Sun3, 386i, and
>	286 XENIX machines work correctly (2 windows), while 386 XENIX and
>	Pyramid (AT&T universe) work incorrectly (1 window).
>
> [ code including overwrite()... ]

A couple of weeks ago I spent some time testing overwrite()
extensively.  I checked it on BSD 4.3 running on a VAX, AT&T System
V/R2 (Microport SV/AT 2.2.1L) running on an AT clone, and MS-DOS (using
Bjorn Larsson's PCurses and the Turbo C 1.5 compiler).  I found that
overwrite() was broken (though with subtle differences) on both BSD and
System V.  It worked correctly only on PCurses.  I got a note from a
fellow at AT&T who said that they knew about the bug in earlier System
Vs, and the problem was completely corrected in the forthcoming System
V release (V4, is it?).

Anyway, I concluded that overwrite() (and probably overlay()) are too
commonly broken to allow portability.  This is a sucky answer, but:
your code is right, the library is bugged, and I think you should avoid
using overwrite().

-Dean

Dean Pentcheff        dean@violet.berkeley.edu
----------------------------------------------
As an adolescent I aspired to lasting fame, I craved factual certainty, and I
thirsted for a meaningful vision of human life - so I became a scientist.  This
is like becoming an archbishop so you can meet girls.               M. Cartmill