[comp.unix.ultrix] Bug in 2.0 NFS

jpn@teddy.UUCP (John P. Nelson) (12/23/87)

We have discovered a bug in the ULTRIX 2.0 implementation of NFS.

The bug is that the "utimes" system call returns an error if applied
over NFS to a read-only file that resides on an ULTRIX 2.0 machine.

"utimes" is the call that changes the access and modify times on a
file.  The manual page describes that all that is required is that
you be the owner of the file (or root).  No mention of a write access
requirement is mentioned, and in fact, if the same operation is done
on the same file, but LOCALLY (i.e. not through NFS), then it succeeds.

This bug affects "mv", "tar", and probably other programs as well.
We have notified DEC of the bug, but we are told that there is no
chance of obtaining a fix before Ultrix 2.2 is released, and maybe
not even then.

---
John P. Nelson
   decvax!genrad!teddy!jpn
   mit-eddie!genrad!teddy!jpn
   ARPA!talcott!panda!teddy!jpn

matt@oddjob.UUCP (Godfather to putty-tats) (12/25/87)

John P. Nelson writes:
) The bug is that the "utimes" system call returns an error if applied
) over NFS to a read-only file that resides on an ULTRIX 2.0 machine.
) ... if the same operation is done
) on the same file, but LOCALLY (i.e. not through NFS), then it succeeds.

Are you saying that utimes() can change the timestamps on a file on a
local read-only file system?  If so, then THAT is the bug, and a
serious one.  If instead you are talking about a f.s. that is R/W on
its local system, but which has been mounted by another host as R/O,
then everything is behaving just as it should.  On a R/O file system
it's not just the file contents that are unwritable, but everything
about the file system, including the inodes.

) We have notified DEC of the bug, but we are told that there is no
) chance of obtaining a fix before Ultrix 2.2 is released, and maybe
) not even then.

If DEC agreed that this was a bug, then either they did not
understand you or you talked to someone who didn't know much.
________________________________________________________
Matt	     University		matt@oddjob.uchicago.edu
Crawford     of Chicago     {astrovax,ihnp4}!oddjob!matt

jpn@teddy.UUCP (John P. Nelson) (12/31/87)

I guess my first posting wasn't entirely clear.  matt@oddjob obviously
got the wrong idea, others might have as well.

)John P. Nelson writes:
) The bug is that the "utimes" system call returns an error if applied
) over NFS to a read-only file that resides on an ULTRIX 2.0 machine.
) ... if the same operation is done
) on the same file, but LOCALLY (i.e. not through NFS), then it succeeds.

>matt@oddjob.UUCP (Godfather to putty-tats) writes:
>
>Are you saying that utimes() can change the timestamps on a file on a
>local read-only file system?

I said nothing about read-only FILESYSTEMS.  I am talking about a FILE
which is mode 0444 on a filesystem mounted both R/W locally and R/W
over NFS.  The utimes() call functions properly locally, but fails
over NFS.

This is a real bug.  We have also been informed by DEC that they are
aware of the bug, and it is fixed in Ultrix 2.2.

John P. Nelson
   decvax!genrad!teddy!jpn
   mit-eddie!genrad!teddy!jpn
   ARPA!talcott!panda!teddy!jpn