The following functions provide an interface to extract and manipulate
the header entry (see Header Entry) from a file loaded in memory.
The meta information must be written back into the domain message with
the empty string as
Returns the header entry of a domain from file, a PO file loaded in
memory. The value
NULL provided as domain denotes the
default domain. Returns
NULL if there is no header entry.
Returns the value of field in the header entry. The return
value is either a freshly allocated string, to be freed by the caller,
Returns a freshly allocated string which contains the entry from header with field set to value. The field is added if necessary.