Gd_field_list retrieve a list of fields in a dirfile
#include <getdata.h> const char **gd_field_list(DIRFILE *dirfile);
The gd_field_list() function queries a dirfile(5) database specified by dirfile and returns a read-only list of names of the all fields defined in the database. Notably, this list does not include /META subfields.
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. The array is terminated by a NULL pointer. The number of strings in the array can be obtained from a call to gd_nfields(3).
The caller may not modify any strings in the array, or the array itself. Doing so may cause database corruption. The pointer returned is guaranteed to be valid until gd_field_list() is called again on the same DIRFILE object, or until the array is de-allocated by a call to gd_close(3).
Upon successful completion, gd_field_list() returns a pointer to an array of strings containing the names of all the fields defined in the dirfile database. 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.
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).