SYNOPSIS
#include <getdata.h>- const char *gd_reference(DIRFILE *dirfile, const char *field_code);
DESCRIPTION
RETURN VALUE
On success, gd_reference() returns the field code of the dirfile's reference field, which will be field_code, if field_code is non-NULL. If no RAW fields are defined in the dirfile, this function will return NULL, without raising an error. On error, NULL is returned and the dirfile error is set to a non-zero error value. Possible error values are:- GD_E_ACCMODE
- The specified dirfile was opened read-only.
- GD_E_ALLOC
- The library was unable to allocate memory.
- GD_E_BAD_CODE
- The field specified by field_code was not found.
- GD_E_BAD_DIRFILE
- The supplied dirfile was invalid.
- GD_E_BAD_FIELD_TYPE
- The field specified by field_code was not a RAW field.
- GD_E_PROTECTED
- The metadata of the primary format specification fragment (the file named format in the root dirfile directory) was protected from change.
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).