RFE: stat(1) flag for learning the d_type value of a given file

[Eric Blake]

The Cygwin developers have been trying to improve some d_type hints
given during readdir(), to return DT_DIR instead of DT_UNKNOWN for
obvious directories, as an example.  But testing the patches for
correctness has proved to be a bit of a challenge for testing.  On an
IRC chat, we discovered that it is really difficult to find out what
d_type lists for a given file without using a debugger or writing a
custom program - most GNU code is using it as an optimization to avoid
lstat(), but never directly outputs that the optimization took place.
So the idea was raised: could we teach stat(1) a new format arg that
would make it painfully obvious what d_type hint is associated with a
given file?

Of course, such a format is not trivial, and must not be part of the
default stat output.  Given 'stat --format=... a', you'd have to do
readdir() on "." until you find "a", in order to get to the d_type.  But
I couldn't think of any better utility to enhance to easily get at
d_type information from the shell.  At least, stat(1) feels like a
better choice than ls(1) for adding the enhanced output information.

What do you think? Should I spend time writing up a patch?

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

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