[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]
kern/42130: NFS: open(...O_CREAT...) fails, yet file is created
>Synopsis: NFS: open(...O_CREAT...) fails, yet file is created
>Arrival-Date: Sat Sep 26 16:55:00 +0000 2009
>Originator: Edgar Fuß
Mathematisches Institut der Uni Bonn
NetBSD xxx 4.0_STABLE NetBSD 4.0_STABLE (xxx) #x: xxx amd64
There is at least one situation where an open(...O_CREAT...) fails, yet the
file in question is created:
1. The file is on NFS
2. flags include O_EXCL
3. mode includes S_ISGID
4. the parent directory belongs to a group the user is not a member of
This happens with both NetBSD and Linux NFS clients (they differ in errno,
being EPERM on NetBSD and EIO on Linux).
I suspect this is a consequence of the open(2) being split into multiple NFS
RPCs, some of which succeed and some of which fail.
On a local fs, the open() just fails without the file being created.
I'm not sure what POSIX says about this situation; the current behaviour is
somewhat surprising to me.
On an NFS file system:
mkdir(1) a directory
chown(1) the directory to user:group where user is NOT a member of group
as user, inside the directory, execute an open(2) with flags O_CREAT|O_EXCL and
Main Index |
Thread Index |