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Re: [PATCH] Fix wordsize-32 mmap offset for negative value (BZ#18877)

From: "Dmitry V. Levin" <ldv at altlinux dot org>
To: Joseph Myers <joseph at codesourcery dot com>
Cc: Adhemerval Zanella <adhemerval dot zanella at linaro dot org>, GNU C Library <libc-alpha at sourceware dot org>
Date: Thu, 28 Jan 2016 22:43:04 +0300
Subject: Re: [PATCH] Fix wordsize-32 mmap offset for negative value (BZ#18877)
Authentication-results: sourceware.org; auth=none
References: <55DF6F59 dot 3000404 at linaro dot org> <alpine dot DEB dot 2 dot 10 dot 1601202136590 dot 10142 at digraph dot polyomino dot org dot uk>

On Wed, Jan 20, 2016 at 09:44:26PM +0000, Joseph Myers wrote:
> I'm looking at failures of this new test for MIPS, but am puzzled by the 
> descriptions of this issue in terms of things being incorrect and fixed 
> without any statement of what is actually correct or why that is correct.
> 
> The expectation in the test seems to be that negative offsets passed to 
> mmap should be interpreted as large unsigned values.  But I can't find 
> anything in POSIX, or in the glibc manual, or in the Linux man-pages 
> collection, to justify those semantics.  So what is the basis for that 
> interpretation as part of the glibc API (and for its being compatible with 
> POSIX), rather than negative arguments being considered invalid?

Is there any 32-bit kernel currently supported by glibc where underlying
system call doesn't operate with 4K or pagesize units for offsets?


-- 
ldv

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References:
- Re: [PATCH] Fix wordsize-32 mmap offset for negative value (BZ#18877)
  - From: Joseph Myers

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