gd_constants(3)

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.

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)