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Re: New platform independent problem
- From: Corinna Vinschen <corinna-cygwin at cygwin dot com>
- To: cygwin at cygwin dot com, emacs-devel at gnu dot org, Eli Zaretskii <eliz at gnu dot org>
- Date: Fri, 20 Jan 2006 13:25:59 +0100
- Subject: Re: New platform independent problem
- References: <43D0797C.firstname.lastname@example.org> <email@example.com>
- Reply-to: cygwin at cygwin dot com, emacs-devel at gnu dot org, Eli Zaretskii <eliz at gnu dot org>
On Jan 20 13:08, Eli Zaretskii wrote:
> > Date: Fri, 20 Jan 2006 14:47:40 +0900
> > From: djh
> > In December of last year, 2005, the cygwin developers deprecated d_ino
> > out of the dirent.h defined dirent structure.
> > This break emac's dired.c (from compiling)
> > Ref: http://www.cygwin.com/ml/cygwin/2005-12/msg00205.html
> Without knowing the full details, I'd risk saying that this was not
> the best decision. Is there really no way of making d_ino be
> consistent with what `stat' returns about the same directory?
The problem is that the Windows functions for reading directory content
don't return the inode number(*), so we ended up using a namehash for
the d_ino member. Otherwise, to get the inode number for the files'
directory entry, we would have to open each file to get a handle, then
call GetFileInformationByHandle, and then have to close the handle
again. This would make the readdir function *very* slow.
The other alternative would be to use always a namehash, also in the
st_ino case. The problem with this approach is that hardlinks to the
same file would have different inode numbers, which then confuse tar or
> In any case, I think removing the member is a solution that is much
> worse than the problem: many programs refer to d_ino, but don't
> require too much from its contents. These programs will now fail to
> compile. I don't think that the goal of educating the maintainers of
> Bash and Find (a worthy goal in itself) justifies breaking the other
> If making d_ino consistent with st_ino is impossible, a better way of
> dealing with problems in Bash and Find is to make changes in those
> packages' sources that are specific to Cygwin.
I'm also having a problem right now building rcp and scp due to the
missing d_ino. OTOH, the d_ino member is not required by POSIX, but
only in X/Open compliant OSes, see
So, portable applications shouldn't rely on d_ino.
Whether we should revert to using d_ino or not, I'm not sure. From a
Windows perspective, it's a step in the right direction. From an
application portability perspective, it should be ok to do it. From a
Linux compatibility perspective, which we claim, it might be somewhat
hazardous to drop d_ino, though.
(*) Beginning with Windows XP, two such functions exist now, but they
won't help for older OSes, obviously.
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Project Co-Leader cygwin AT cygwin DOT com
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