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Re: [RFC] DT_WHT
- From: Ben Hutchings <ben dot hutchings at codethink dot co dot uk>
- To: Rical Jasan <ricaljasan at pacific dot net>, libc-alpha <libc-alpha at sourceware dot org>
- Date: Thu, 01 Mar 2018 16:24:31 +0000
- Subject: Re: [RFC] DT_WHT
- Authentication-results: sourceware.org; auth=none
- References: <280ca5c0-a265-9f58-2ddf-32a1ef130167@pacific.net>
On Wed, 2018-02-21 at 02:16 -0800, Rical Jasan wrote:
> There is one undocumented DT_* macro in manual/filesys.texi: DT_WHT. It
> is defined in dirent/dirent.h and appears to be used once in io/fts.c:
>
> #if defined FTS_WHITEOUT && 0
> if (dp->d_type == DT_WHT)
> p->fts_flags |= FTS_ISW;
> #endif
>
> For an entry in the manual, I was thinking something along the lines of:
>
> "This macro is obsolete and has no effect. It was used to..."
>
> but I'm not sure what to say about what it was used for.
[...]
> Lastly, I can't find a reference to it in any of the standards I've
> managed to obtain so far (not to say that's exhaustive at all). Is this
> also BSD?
Some Linux filesystems support white-out directory entries for use with
union filesystems. At least the coda and xfs implementations of
getdents() appear to be capable of setting d_type to DT_WHT.
Ben.
--
Ben Hutchings
Software Developer, Codethink Ltd.