NAME

       gd_constants — retrieve a list of CARRAY values from a dirfile

SYNOPSIS

       #include <getdata.h>

       const gd_carray_t *gd_mcarrays(DIRFILE *dirfile, const char *parent, gd_type_t
              return_type);

DESCRIPTION

       The gd_mcarrays() function queries a dirfile(5) database specified by dirfile and  returns
       a  read-only  list  of  values of the all CARRAY metafields for the supplied parent field,
       after type conversion to the data type specified by return_type.   For  a  list  of  valid
       symbols to use for return_type, see the gd_get_carray(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, except that it is guaranteed to be in the same order as the list of  CARRAY  fields
       returned  by gd_mfield_list_by_type(3).  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, nor the array  itself.   Doing  so  may
       cause  database  corruption.   The  pointer  returned is guaranteed to be valid only until
       gd_mcarrays() is called again, 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_mcarrays()  returns a pointer to an array of gd_carray_t
       objects containing the values of all the CARRAYs defined in  the  dirfile  database.   The
       gd_carray_t is defined as:

           typedef struct {
             size_t       n;              /* array_len */
             void        *d;              /* CARRAY data */
           } gd_carray_t;

       where  n  specifies  the  length  of the CARRAY data, and d is an array of the data values
       themselves.  The caller should cast the  void  pointer  to  a  type  appropriate  for  the
       return_type  specified.   The  list is terminated by an end-of-list marker consisting of a
       gd_carray_t item with n set to zero.

       If no CARRAYs are defined in the database, a list containing only the  end-of-list  marker
       is  returned.   On  error, gd_mcarrays() 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_carrays(3),    gd_error(3),    gd_error_string(3),    gd_get_carray(3),
       gd_mfield_list_by_type(3), gd_nmfields_by_type(3), gd_open(3)