Re: bin/55815: tar opens device files

[Robert Elz <kre%munnari.OZ.AU@localhost>]

The following reply was made to PR bin/55815; it has been noted by GNATS.

From: Robert Elz <kre%munnari.OZ.AU@localhost>
To: Joerg Sonnenberger <joerg%bec.de@localhost>
Cc: gnats-bugs%netbsd.org@localhost, martin%NetBSD.org@localhost
Subject: Re: bin/55815: tar opens device files
Date: Thu, 26 Nov 2020 02:06:34 +0700

     Date:        Wed, 25 Nov 2020 19:06:26 +0100
     From:        Joerg Sonnenberger <joerg%bec.de@localhost>
     Message-ID:  <20201125180626.GA111551%bec.de@localhost>
 
   | No, it is about ensuring that the extattr and ACL actually belong to the
   | same object as the rest of the permissions.
 
 Ah, OK.
 
 Is this for creating the archive, or extracting it?
 
 In the creating case, does it really matter?   If the filesystem is
 changing while attempting to create an archive, then there's got to
 be race conditions, and while it would be nice to correctly add either
 the before, or the after to the archive, I'm not sure that's important
 enough to really matter.
 
 In the extracting case, at least when extracting a non-openable (or
 potentially non-openable) file, couldn't tar extract to a file in a
 randomnly named 700 mode sub-dir, set the attributes/acl on the file in
 that sub-dir, and then rename it to where it belongs?
 
 Wouldn't any attempt to open the file (almost) necessarily hang when
 the file is a fifo ?   But those deserve to be archived/extracted
 just as accurately as regular files, directories, and special files.
 (I'm not sure the same is true of sockets, but perhaps).
 
 kre