String.freeToBytes

Transfers ownership of the contents of string to a newly allocated #GBytes. The #GString structure itself is deallocated, and it is therefore invalid to use string after invoking this function.

Note that while #GString ensures that its buffer always has a trailing nul character (not reflected in its "len"), the returned #GBytes does not include this extra nul; i.e. it has length exactly equal to the "len" member.