ui/common: Don't talloc_free sysinfo and status explicitly

Currently, we talloc_free() the sysinfo and status messages in the
discover client, right after performing the ui's callback.

However, the client may wish to keep a reference to this information
beyond the callback invocation. This change introduces a per-message
talloc context, which these structures are allocated under. This allows
the callbacks to talloc_steal() anything they wish to keep a reference
to.

Signed-off-by: Jeremy Kerr <jk@ozlabs.org>

1 files changed, 9 insertions, 0 deletions

diff --git a/ui/common/discover-client.h b/ui/common/discover-client.h
index 6aa0432..fa97fa5 100644
--- a/ui/common/discover-client.h
+++ b/ui/common/discover-client.h
@@ -18,6 +18,15 @@ struct pb_boot_data {
  * @device_add: PB_PROTOCOL_ACTION_ADD event callback.
  * @device_remove: PB_PROTOCOL_ACTION_REMOVE event callback.
  * @cb_arg: Client managed convenience variable passed to callbacks.
+ *
+ * The discover client holds talloc references to the devices (and the
+ * devices' boot options), so callbacks may store boot options and devices
+ * as long as the client remains allocated.
+ *
+ * The boot_status and system_info structs are allocated by the client,
+ * and will be free()ed after the callback is invoked. If the callback
+ * stores these structures for usage beyond the duration of the callback,
+ * it must talloc_steal() them.
  */
 
 struct discover_client_ops {