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Date: Wed, 05 Mar 2014 06:52:24 -0700
From: Eric Blake <eblake@redhat.com>
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To: cygwin@cygwin.com
Subject: Re: struct tm problem
References: <CAJoYywWqyBYEJKriugeU0deHm=DsS_LYgHotaX6K=q6TO_tmQQ@mail.gmail.com>	<20140304081928.GF7236@calimero.vinschen.de> <CAJoYywUF2gpX5+-9H3gExyRMYUtJQyi_mHOX42uG9kRfaQ0Nvg@mail.gmail.com>
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On 03/05/2014 03:45 AM, Irfan Adilovic wrote:
> If it is recognized that the executable was compiled against a
> different sized struct tm, how would you instruct cygwin1.dll code not
> to write to tm_gmtoff?

Linker magic, the same as how we converted to 64-bit stat, and the same
as what we will eventually have to do if we want to convert to 64-bit
time_t.  Basically, we add a new entry point, and alias the public name
to the new entry point.  Any old program is still linked to the old
name, where we know they use the smaller size.  Any new program is
linked to the new name, where we know they use the larger size.  New
programs cannot run against the old dll, but the new dll is able to
handle both old and new apps by virtue of dual entry points.

--=20
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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