+The convention in all functions that return C<int> is that they return
+C<-1> to indicate an error. You can get additional information on
+errors by calling C<guestfs_last_error> and/or by setting up an error
+handler with C<guestfs_set_error_handler>.
+
+The default error handler prints the information string to C<stderr>.
+
+Out of memory errors are handled differently. The default action is
+to call L<abort(3)>. If this is undesirable, then you can set a
+handler using C<guestfs_set_out_of_memory_handler>.
+
+=head2 guestfs_last_error
+
+ const char *guestfs_last_error (guestfs_h *handle);
+
+This returns the last error message that happened on C<handle>. If
+there has not been an error since the handle was created, then this
+returns C<NULL>.
+
+The lifetime of the returned string is until the next error occurs, or
+C<guestfs_close> is called.
+
+The error string is not localized (ie. is always in English), because
+this makes searching for error messages in search engines give the
+largest number of results.
+
+=head2 guestfs_set_error_handler
+
+ typedef void (*guestfs_error_handler_cb) (guestfs_h *handle,
+ void *data,
+ const char *msg);
+ void guestfs_set_error_handler (guestfs_h *handle,
+ guestfs_error_handler_cb cb,
+ void *data);
+
+The callback C<cb> will be called if there is an error. The
+parameters passed to the callback are an opaque data pointer and the
+error message string.
+
+Note that the message string C<msg> is freed as soon as the callback
+function returns, so if you want to stash it somewhere you must make
+your own copy.
+
+The default handler prints messages on C<stderr>.
+
+If you set C<cb> to C<NULL> then I<no> handler is called.
+
+=head2 guestfs_get_error_handler
+
+ guestfs_error_handler_cb guestfs_get_error_handler (guestfs_h *handle,
+ void **data_rtn);
+
+Returns the current error handler callback.
+
+=head2 guestfs_set_out_of_memory_handler
+
+ typedef void (*guestfs_abort_cb) (void);
+ int guestfs_set_out_of_memory_handler (guestfs_h *handle,
+ guestfs_abort_cb);
+
+The callback C<cb> will be called if there is an out of memory
+situation. I<Note this callback must not return>.