NAME

       gd_constants — retrieve a list of constant values from a dirfile

SYNOPSIS

       #include <getdata.h>

       const void *gd_constants(DIRFILE *dirfile, gd_type_t return_type);

DESCRIPTION

       The gd_constants() function queries a dirfile(5) database specified by dirfile and returns
       a read-only list of values of the all CONST type fields defined in the database after type
       conversion to the data type specified by return_type.  Notably, this list does not include
       /META  subfields.   For  a  list  of  valid  symbols  to  use  for  return_type,  see  the
       gd_get_constant(3) man page.

       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_field_list_by_type(3).  The array is unterminated.  The number of values in
       the array can be obtained from a call to gd_nfields_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 only until
       gd_constants() is called again with the same arguments, or until the dirfile's metadata is
       modified  (by  adding, modifying or deleting an entry), 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_field_list_by_type(3).

RETURN VALUE

       Upon  successful  completion,  gd_constants()  returns  a  pointer  to  an array of values
       containing the values of all the  constants  defined  in  the  dirfile  database.   If  no
       constants  are  defined  in  the database, 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_DIRFILE
               The supplied dirfile was invalid.

       GD_E_BAD_TYPE
               The return_type specified was invalid.

       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 GetData
               developers.

       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_open(3),   gd_error(3),   gd_error_string(3),   gd_field_list_by_type(3),
       gd_get_constant(3), gd_nfields_by_type(3)