NAME

       gd_mconstants — retrieve a list of constant values from a dirfile

SYNOPSIS

       #include <getdata.h>

       const void *gd_mconstants(DIRFILE *dirfile, const char *parent, gd_type_t return_type);

DESCRIPTION

       The  gd_mconstants()  function  queries  a  dirfile(5)  database  specified by dirfile and
       returns a read-only list of values of the all  CONST  type  metafields  for  the  supplied
       parent field after type conversion to the data type specified by return_type.

       The  dirfile argument must point to a valid DIRFILE object previously created by a call to
       gd_open(3).

       The array returned will be de-allocated by a call to gd_close(3) and  should  not  be  de-
       allocated  by the caller.  The list returned should not be assumed to be in any particular
       order, although it is guaranteed to be in the same order  as  the  list  of  CONST  fields
       returned  by  gd_mfield_list_by_type(3).  The array is unterminated.  The number of values
       in the array can be obtained from a call to gd_nmfields_by_type(3).

       The caller may not modify any values in the array, or the  array  itself.   Doing  so  may
       cause  database  corruption.   The  pointer  returned  is  guaranteed  to  be  valid until
       gd_mconstants() is called again,  or  until  the  array  is  de-allocated  by  a  call  to
       gd_close(3).

       A   corresponding   list   of   names   for  these  fields  may  be  obtained  by  calling
       gd_mfield_list_by_type(3).

RETURN VALUE

       Upon successful completion, gd_mconstants() returns  a  pointer  to  an  array  of  values
       containing  the  values of all the CONST metafields for the supplied parent field.  If the
       parent field has no constant metafields, NULL is returned.  On error it returns  NULL  and
       sets the dirfile error to a non-zero error value.  Possible error values are:

       GD_E_ALLOC
               The library was unable to allocate memory.

       GD_E_BAD_CODE
               The supplied parent field code was not found, or referred to a metafield itself.

       GD_E_BAD_DIRFILE
               The supplied dirfile was invalid.

       GD_E_BAD_TYPE
               The return_type specified was invalid.

       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

       dirfile(5),       gd_error(3),        gd_error_string(3),        gd_field_list_by_type(3),
       gd_nfields_by_type(3), gd_mcarrays(3), gd_open(3)