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Date: Mon, 17 May 2004 16:37:36 +0100
From: viro@parcelfarce.linux.theplanet.co.uk
To: Linus Torvalds <torvalds@osdl.org>
Cc: "Theodore Ts'o" <tytso@mit.edu>, Wayne Scott <wscott@bitmover.com>,
       akpm@osdl.org, elenstev@mesatop.com, lm@bitmover.com,
       wli@holomorphy.com, hugh@veritas.com, adi@bitmover.com, scole@lanl.gov,
       support@bitmover.com, linux-kernel@vger.kernel.org
Subject: Re: 1352 NUL bytes at the end of a page?
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References: <200405162136.24441.elenstev@mesatop.com> <Pine.LNX.4.58.0405162152290.25502@ppc970.osdl.org> <20040516231120.405a0d14.akpm@osdl.org> <20040517.085640.30175416.wscott@bitmover.com> <20040517151738.GA4730@thunk.org> <Pine.LNX.4.58.0405170820560.25502@ppc970.osdl.org>
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On Mon, May 17, 2004 at 08:22:10AM -0700, Linus Torvalds wrote:
> 
> 
> On Mon, 17 May 2004, Theodore Ts'o wrote:
> > 
> > Note though that the stdio library uses a writeable mmap to implement
> > fwrite.
> 
> It does? Whee. Then I'll have to agree with Andrew - if there is a path 
> that is more likely to have bugs, it's trying to do writes with mmap and 
> ftruncate.
> 
> Who came up with that braindead idea? Is it some crazed Mach developer 
> that infiltrated the glibc development group?

IIRC, that idiocy had been disabled by default (note that it's inherently
broken, since truncate() between your mmap() and memcpy() will lead to
a coredump, which is not something fwrite() is allowed to do in such
situation).

strace should show if there such mmap calls are made, anyway.  Did they
show up in the traces?