Re: bootstrap/5149: gcc-20011217 reads beyond EOF on cygwin

[Zack Weinberg <zack@codesourcery.com>]

The following reply was made to PR bootstrap/5149; it has been noted by GNATS.

From: Zack Weinberg <zack@codesourcery.com>
To: Neil Booth <neil@daikokuya.demon.co.uk>
Cc: Werner Tuchan <tuwn@gmx.net>, neil@gcc.gnu.org, gcc-bugs@gcc.gnu.org,
	gcc-gnats@gcc.gnu.org
Subject: Re: bootstrap/5149: gcc-20011217 reads beyond EOF on cygwin
Date: Thu, 20 Dec 2001 10:57:47 -0800

 On Thu, Dec 20, 2001 at 06:33:23PM +0000, Neil Booth wrote:
 > 
 > Weird.  The bytes after EOF are a mixture of NULs and 0xc0.  Is 0xc0
 > of special significance in Windows?  Is your version of cygwin the
 > latest?  I recall some talk about mmap bugs in cygwin.
 > 
 > I guess that we have to disable mmap() on cygwin, or at least on
 > specific versions.  Do you have any better ideas Zack?
 
 No.  But the AC_FUNC_MMAP_FILE macro (gcc/aclocal.m4) already executes
 a test program to determine whether or not mmap works the way we want.
 It would be easy enough to add a check that byte (len+1) of its test
 file is a NUL.  [And we'd better not be looking at byte len+2, or
 we'll segfault if the file length is one less than a multiple of
 PAGE_SIZE.]
 
 zw