dbus-c++: MessageIter: handle nested dicts in copy_data

MessageIter: handle nested dicts in copy_data

MessageIter::copy_data is calling dbus_message_iter_open_container (in
libdbus) with an invalid |contained_signature| argument when |type| is
complex. This triggers an assertion failure when the args are checked.

The comments for dbus_message_iter_open_container say: "For variants,
the contained_signature should be the type of the single value inside
the variant. For structs and dict entries, contained_signature should be
NULL; it will be set to whatever types you write into the struct. For
arrays, contained_signature should be the type of the array elements."

However, the existing code only follows this guideline for arrays. It
does the opposite of what is specified (passing NULL when a type
signature string is required and vice versa) for variants, structs, and
dict entries.

This issue was identified and this fix proposed in the upstream issue
tracker (see
http://sourceforge.net/tracker/?func=detail&aid=3151818&group_id=236997&atid=1101682),
but the fix has not yet been applied upstream and the issue remains open.

This issue was causing cashewd to abort when making a GetProperties
D-Bus call to flimflam's Device interface because of the nesting in the
newly added Cellular.SIMLockStatus property (see issue 11293).

BUG=chromium-os:13850
TEST=manual testing on device

Change-Id: Ia29dc64dd9f7627413fc1c1f1fbf8d516336447c

Committed: http://chrome-svn/viewvc/chromeos?view=rev&revision=32fe2ce

[Jason Glasgow, 2011-04-11 19:05:34]

LGTM