ffpos(3C)

NAME
     ffpos - Positions files opened using flexible file I/O

SYNOPSIS
     #include <ffio.h>

        off_t ffpos (int fd, int cmd, void *arg , int len, struct ffsw
        *stat);

DESCRIPTION
     The ffpos function provides a way of positioning files opened by
     ffopen or ffopens (see ffopen(3C)), using flexible file I/O (FFIO).
     The arguments are as follows:

     fd     Value returned by ffopen or ffopens.

     cmd    Specifies a value defined in header file ffio.h.  See the
            following subsection, VALUES FOR cmd ARGUMENT.

     arg    The type and value of this argument is cmd specific.  See
            preceding descriptions.

     len    If cmd = FP_GETPOS or FP_SETPOS, len specifies the number of
            Cray words in arg.  This parameter is ignored for other values
            of cmd.

     stat   Pointer to the status return structure.

   Values for cmd Argument
     The following values can be used for the cmd argument introduced
     above.

     FP_GABS
         Returns information about the current position in arg, which can
         later be used by a call to ffpos with cmd = FP_SABS.  arg is a
         pointer to structure fp_abs (defined in header file ffio.h).


     ffp_nv
         Number of volumes to position; should always be a positive number.
         A volume number of 0 indicates no volume positioning is to be
         performed.

     ffp_nvs_p
         Indicates the direction of volume positioning.  The following
         values are defined in header file ffio.h:

         FP_TPOS_FORW   The number of volumes to skip forward, relative to
                        the current position.

         FP_TPOS_BACK   The number of volumes to skip backward, relative to
                        the current position.

         FP_TPOS_ABS    Specifies an absolute volume number, relative to
                        the beginning of the volume identifier list
                        (specified on the tpmnt(1) command.)

     ffp_vi
         Name of volume identifier to be mounted.  A nonzero ffp_vi field
         is invalid if ffp_nbs_p is FP_TPOS_FORW or FP_TPOS_BACK or if
         ffp_nvs is FP_TPOS_FORW or FP_TPOS_BACK and ffp_nv is nonzero.

RETURN VALUES
     If cmd is FP_BSEEK, ffpos returns the new bit position of the file on
     success.  For other values of cmd, the ffpos function returns 0 on
     success.  On failure, it returns -1 and the sw_error field of the stat
     structure contains the error number.

SEE ALSO
     ffopen(3C)

     tpmnt(1) in the