rfc1813.txt

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RFC 1813                 NFS Version 3 Protocol                June 1995


   ACCESS
         An ACCESS procedure has been added to allow an explicit
         over-the-wire permissions check. This addresses known
         problems with the superuser ID mapping feature in many
         server implementations (where, due to mapping of root
         user, unexpected permission denied errors could occur
         while reading from or writing to a file).  This also
         removes the assumption which was made in the NFS
         version 2 protocol that access to files was based
         solely on UNIX style mode bits.

   READ
         The reply structure includes a Boolean that is TRUE if
         the end-of-file was encountered during the READ.  This
         allows the client to correctly detect end-of-file.

   WRITE
         The beginoffset and totalcount fields were removed from
         the WRITE arguments. The reply now includes a count so
         that the server can write less than the requested
         amount of data, if required. An indicator was added to
         the arguments to instruct the server as to the level of
         cache synchronization that is required by the client.

   CREATE
         An exclusive flag and a create verifier was added for
         the exclusive creation of regular files.

   MKNOD
         This procedure was added to support the creation of
         special files. This avoids overloading fields of CREATE
         as was done in some NFS version 2 protocol
         implementations.

   READDIR
         The READDIR arguments now include a verifier to allow
         the server to validate the cookie. The cookie is now a
         64 bit unsigned integer instead of the 4 byte array
         which was used in the NFS version 2 protocol.  This
         will help to reduce interoperability problems.

   READDIRPLUS
         This procedure was added to return file handles and
         attributes in an extended directory list.

   FSINFO
         FSINFO was added to provide nonvolatile information
         about a file system. The reply includes preferred and



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RFC 1813                 NFS Version 3 Protocol                June 1995


         maximum read transfer size, preferred and maximum write
         transfer size, and flags stating whether links or
         symbolic links are supported.  Also returned are
         preferred transfer size for READDIR procedure replies,
         server time granularity, and whether times can be set
         in a SETATTR request.

   FSSTAT
         FSSTAT was added to provide volatile information about
         a file system, for use by utilities such as the Unix
         system df command. The reply includes the total size
         and free space in the file system specified in bytes,
         the total number of files and number of free file slots
         in the file system, and an estimate of time between
         file system modifications (for use in cache consistency
         checking algorithms).

   COMMIT
         The COMMIT procedure provides the synchronization
         mechanism to be used with asynchronous WRITE
         operations.

2. RPC Information

2.1 Authentication

   The NFS service uses AUTH_NONE in the NULL procedure. AUTH_UNIX,
   AUTH_DES, or AUTH_KERB are used for all other procedures. Other
   authentication types may be supported in the future.

2.2 Constants

   These are the RPC constants needed to call the NFS Version 3
   service.  They are given in decimal.

      PROGRAM  100003
      VERSION  3

2.3 Transport address

   The NFS protocol is normally supported over the TCP and UDP
   protocols.  It uses port 2049, the same as the NFS version 2
   protocol.

2.4 Sizes

   These are the sizes, given in decimal bytes, of various XDR
   structures used in the NFS version 3 protocol:



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RFC 1813                 NFS Version 3 Protocol                June 1995


   NFS3_FHSIZE 64
      The maximum size in bytes of the opaque file handle.

   NFS3_COOKIEVERFSIZE 8
      The size in bytes of the opaque cookie verifier passed by
      READDIR and READDIRPLUS.

   NFS3_CREATEVERFSIZE 8
      The size in bytes of the opaque verifier used for
      exclusive CREATE.

   NFS3_WRITEVERFSIZE 8
      The size in bytes of the opaque verifier used for
      asynchronous WRITE.

2.5 Basic Data Types

   The following XDR definitions are basic definitions that are
   used in other structures.

   uint64
         typedef unsigned hyper uint64;

   int64
         typedef hyper int64;

   uint32
         typedef unsigned long uint32;

   int32
         typedef long int32;

   filename3
         typedef string filename3<>;

   nfspath3
         typedef string nfspath3<>;

   fileid3
         typedef uint64 fileid3;

   cookie3
         typedef uint64 cookie3;

   cookieverf3
         typedef opaque cookieverf3[NFS3_COOKIEVERFSIZE];





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RFC 1813                 NFS Version 3 Protocol                June 1995


   createverf3
         typedef opaque createverf3[NFS3_CREATEVERFSIZE];

   writeverf3
         typedef opaque writeverf3[NFS3_WRITEVERFSIZE];

   uid3
         typedef uint32 uid3;

   gid3
         typedef uint32 gid3;

   size3
         typedef uint64 size3;

   offset3
         typedef uint64 offset3;

   mode3
         typedef uint32 mode3;

   count3
         typedef uint32 count3;

   nfsstat3
      enum nfsstat3 {
         NFS3_OK             = 0,
         NFS3ERR_PERM        = 1,
         NFS3ERR_NOENT       = 2,
         NFS3ERR_IO          = 5,
         NFS3ERR_NXIO        = 6,
         NFS3ERR_ACCES       = 13,
         NFS3ERR_EXIST       = 17,
         NFS3ERR_XDEV        = 18,
         NFS3ERR_NODEV       = 19,
         NFS3ERR_NOTDIR      = 20,
         NFS3ERR_ISDIR       = 21,
         NFS3ERR_INVAL       = 22,
         NFS3ERR_FBIG        = 27,
         NFS3ERR_NOSPC       = 28,
         NFS3ERR_ROFS        = 30,
         NFS3ERR_MLINK       = 31,
         NFS3ERR_NAMETOOLONG = 63,
         NFS3ERR_NOTEMPTY    = 66,
         NFS3ERR_DQUOT       = 69,
         NFS3ERR_STALE       = 70,
         NFS3ERR_REMOTE      = 71,
         NFS3ERR_BADHANDLE   = 10001,



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RFC 1813                 NFS Version 3 Protocol                June 1995


         NFS3ERR_NOT_SYNC    = 10002,
         NFS3ERR_BAD_COOKIE  = 10003,
         NFS3ERR_NOTSUPP     = 10004,
         NFS3ERR_TOOSMALL    = 10005,
         NFS3ERR_SERVERFAULT = 10006,
         NFS3ERR_BADTYPE     = 10007,
         NFS3ERR_JUKEBOX     = 10008
      };

   The nfsstat3 type is returned with every procedure's results
   except for the NULL procedure. A value of NFS3_OK indicates that
   the call completed successfully. Any other value indicates that
   some error occurred on the call, as identified by the error
   code. Note that the precise numeric encoding must be followed.
   No other values may be returned by a server. Servers are
   expected to make a best effort mapping of error conditions to
   the set of error codes defined. In addition, no error
   precedences are specified by this specification.  Error
   precedences determine the error value that should be returned
   when more than one error applies in a given situation. The error
   precedence will be determined by the individual server
   implementation. If the client requires specific error
   precedences, it should check for the specific errors for
   itself.

2.6 Defined Error Numbers

   A description of each defined error follows:

   NFS3_OK
       Indicates the call completed successfully.

   NFS3ERR_PERM
       Not owner. The operation was not allowed because the
       caller is either not a privileged user (root) or not the
       owner of the target of the operation.

   NFS3ERR_NOENT
       No such file or directory. The file or directory name
       specified does not exist.

   NFS3ERR_IO
       I/O error. A hard error (for example, a disk error)
       occurred while processing the requested operation.

   NFS3ERR_NXIO
       I/O error. No such device or address.




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RFC 1813                 NFS Version 3 Protocol                June 1995


   NFS3ERR_ACCES
       Permission denied. The caller does not have the correct
       permission to perform the requested operation. Contrast
       this with NFS3ERR_PERM, which restricts itself to owner
       or privileged user permission failures.

   NFS3ERR_EXIST
       File exists. The file specified already exists.

   NFS3ERR_XDEV
       Attempt to do a cross-device hard link.

   NFS3ERR_NODEV
       No such device.

   NFS3ERR_NOTDIR
       Not a directory. The caller specified a non-directory in
       a directory operation.

   NFS3ERR_ISDIR
       Is a directory. The caller specified a directory in a
       non-directory operation.

   NFS3ERR_INVAL
       Invalid argument or unsupported argument for an
       operation. Two examples are attempting a READLINK on an
       object other than a symbolic link or attempting to
       SETATTR a time field on a server that does not support
       this operation.

   NFS3ERR_FBIG
       File too large. The operation would have caused a file to
       grow beyond the server's limit.

   NFS3ERR_NOSPC
       No space left on device. The operation would have caused
       the server's file system to exceed its limit.

   NFS3ERR_ROFS
       Read-only file system. A modifying operation was
       attempted on a read-only file system.

   NFS3ERR_MLINK
       Too many hard links.

   NFS3ERR_NAMETOOLONG
       The filename in an operation was too long.




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