NAME

       gd_tell — reposition a dirfile field pointer

SYNOPSIS

       #include <getdata.h>

       off_t gd_tell(DIRFILE *dirfile, const char *field_code);

DESCRIPTION

       The  gd_tell()  function  reports  the  current  position  of the I/O pointer of the field
       field_code in the dirfile(5) database specified by dirfile.

       Only RAW fields (and the implicit INDEX field) have field pointers associated  with  them.
       Calling  gd_tell()  on  a derived field will report the position of the I/O pointer of the
       derived field only if all of it's inputs are positioned the  same.   Otherwise,  an  error
       results.

RETURN VALUE

       Upon  successful  completion, gd_tell() returns the I/O position of the specified field in
       samples.  On error, it returns -1 and set the dirfile error to a non-zero value.  Possible
       error values are:

       GD_E_ALLOC
               The library was unable to allocate memory.

       GD_E_BAD_CODE
               The field specified by field_code, or one of the fields it uses for input, was not
               found in the database.

       GD_E_BAD_DIRFILE
               The supplied dirfile was invalid.

       GD_E_DIMENSION
               The specified field or one of its inputs wasn't of vector type.

       GD_E_DOMAIN
               The I/O position of a derived field wasn't well defined because its  input  fields
               simultaneously read from different places in the same RAW field.

       GD_E_INTERNAL_ERROR
               An  internal error occurred in the library while trying to perform the task.  This
               indicates a bug in the library.  Please report the incident to the maintainer.

       GD_E_IO An error occurred while trying to open or read from a file on  disk  containing  a
               raw field.

       GD_E_RECURSE_LEVEL
               Too  many levels of recursion were encountered while trying to resolve field_code.
               This usually indicates  a  circular  dependency  in  field  specification  in  the
               dirfile.

       GD_E_UNKNOWN_ENCODING
               The  encoding  scheme  of  a  RAW  field  could  not be determined.  This may also
               indicate that the binary file associated with the RAW field could not be found.

       GD_E_UNSUPPORTED
               Reading from dirfiles with the encoding scheme of the  specified  dirfile  is  not
               supported by the library.  See dirfile-encoding(5) for details on dirfile encoding
               schemes.

       The dirfile error may be retrieved by calling gd_error(3).  A descriptive error string for
       the last error encountered can be obtained from a call to gd_error_string(3).

SEE ALSO

       gd_open(3), gd_getdata(3), gd_putdata(3), gd_seek(3).