3.2 General comments on filenames

The following comments apply to all NFS version 3 protocol procedures in which the client provides one or more filenames in the arguments: LOOKUP, CREATE, MKDIR, SYMLINK, MKNOD, REMOVE, RMDIR, RENAME, and LINK.

1. The filename must not be null nor may it be the null string. The server should return the error, NFS3ERR_ACCES, if it receives such a filename. On some clients, the filename, ``'' or a null string, is assumed to be an alias for the current directory. Clients which require this functionality should implement it for themselves and not depend upon the server to support such semantics.

2. A filename having the value of "." is assumed to be an alias for the current directory. Clients which require this functionality should implement it for themselves and not depend upon the server to support such semantics. However, the server should be able to handle such a filename correctly.

3. A filename having the value of ".." is assumed to be an alias for the parent of the current directory, i.e. the directory which contains the current directory. The server should be prepared to handle this semantic, if it supports directories, even if those directories do not contain UNIX-style "." or ".." entries.

4. If the filename is longer than the maximum for the file system (see PATHCONF on page 90, specifically name_max), the result depends on the value of the PATHCONF flag, no_trunc. If no_trunc is FALSE, the filename will be silently truncated to name_max bytes. If no_trunc is TRUE and the filename exceeds the server's file system maximum filename length, the operation will fail with the error, NFS3ERR_NAMETOOLONG.

5. In general, there will be characters that a server will not be able to handle as part of a filename. This set of characters will vary from server to server and from implementation to implementation. In most cases, it is the server which will control the client's view of the file system. If the server receives a filename containing characters that it can not handle, the error, NFS3ERR_EACCES, should be returned. Client implementations should be prepared to handle this side affect of heterogeneity.

See also comments in File name component handling on page 101.