File Sharing Between NFS and CIFS Users 5-5
described in the preceding paragraph, a file with the read-only bit turned on
appears to an NFS client not to have any write permission bits turned on.
If a file has no write permission bits turned on and an NFS client turns on any
write permission bit, the filer turns off the read-only bit for that file.
If a files read-only bit is turned on and an NFS client attempts to find out the per-
mission bits for the file, the actual permission bits for the file are not sent to the
NFS client; instead, the filer sends the permission bits to the NFS client with the
write permission bits masked off.
If a files read-only bit is turned on and a CIFS client turns the read-only bit off, the
filer turns on the owners write permission bit for the file.
Files with the read-only bit turned on are writable only by the superuser.
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Whenever the read-only bit is turned on by a client, even if it was already on before
the client did so, the filer tracks whether the client that turned on the bit was an NFS
or CIFS client, as follows:
If the bit was turned on by a CIFS client, renaming the file is not allowed. This is
because file systems on MS-DOS and Windows systems do not allow renaming
a file whose read-only bit has been set. NFS deletes follow NFS conventions.
That is, deletes are allowed if the user has write permission in the parent
directory.
If the bit was turned on by an NFS client that turned off all write permission bits,
removing or renaming the file is allowed if the user has sufficient permission to
do so. This is because file systems on UNIX systems allow removing or renaming
a file that has no write permission bits set.
If the filer is using UNIX-style security, CIFS clients are also allowed to delete a
file with the read-only bit set. This is required for compatibility with standard
UNIX source control programs, such as RCS.
If the filer is configured with PC-style security, the read-only bit is enforced.
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File naming conventions depend on both the network clients operating systems and
the file-sharing protocols. For example, file names are case-sensitive for clients run-
ning UNIX and are case-insensitive, but case-preserving, for clients running Windows
operating systems.
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On the filer, the maximum length of a file name is 255 characters for NFS clients and
CIFS clients that support the PCs long file name format. Some CIFS clients, such as
MS-DOS and Windows 3.x clients, support only file names in the 8.3 format (8 charac-
ters for the file name and 3 characters for the file name extension). In any directory