POSIX, NFS, CPIO/TAR

[Chuck Karish]

In article <2587D93A.19FD at marob.masa.com> dsamperi at marob.masa.com
(Dominick Samperi) wrote:
>Has anyone noticed that the NFS convention of returning uid/gid=-2/-2 (user
>nobody) under certain circumstances results in a corrupted CPIO dump (due
>to sign extension, on a Sun3, for example). I imagine that other UNIX
>utilities are written with the assumption uid >= 0, gid >=0 as well.
>(This only happens when the CPIO "portability" option, -c, is used.)

>Does the POSIX standard (or any other evolving standard) address this
>issue?

  The POSIX 1003.1 standard says that the types used for user and group
  IDs (uid_t and gid_t, respectively) are to be `arithmetic types'.  An
  implementation or application that assumes that that the values are
  always positive is broken.

  Data in all POSIX tar and cpio headers are represented in ASCII,
  as is the case with traditional `cpio -c' archives.

>Where can one find these standards documented, particularly the
>CPIO/TAR standards?

  The POSIX 1003.1 standard is published by the IEEE, 345 East 47th
  Street, New York, NY 10017, USA.  Its ISBN is 1-55937-003-3.

  Tar and cpio archive formats are described in Chapter 10 of the
  document.  The tar, cpio, and pax utilities are covered by
  the 1003.2 draft standard, available only fron the 1003.2
  committee.

	Chuck Karish		karish at mindcraft.com
	(415) 323-9000		karish at forel.stanford.edu