Crash in core::dbus::Object::get_signal

[Pär Bohrarper]

I'm trying to implement Gnome mediakey support using dbus-cpp, but I get a crash when I try to use the MediaPlayerKeyPressed signal.

See attached project. Running it will crash with this stacktrace:

Program received signal SIGSEGV, Segmentation fault.
0x0000000000478fd0 in std::_Hashtable<std::tuple<std::string, std::string>, std::pair<std::tuple<std::string, std::string> const, std::function<void (std::shared_ptr<core::dbus::Message> const&)> >, std::allocator<std::pair<std::tuple<std::string, std::string> const, std::function<void (std::shared_ptr<core::dbus::Message> const&)> > >, std::__detail::_Select1st, std::equal_to<std::tuple<std::string, std::string> >, std::hash<std::tuple<std::string, std::string> >, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<true, false, true> >::_M_find_before_node(unsigned long, std::tuple<std::string, std::string> const&, unsigned long) const (this=0x693ab0, __n=3466715, __k=..., __code=14562117148223712363) at /usr/include/c++/4.8/bits/hashtable.h:1159
1159 __node_base* __prev_p = _M_buckets[__n];
(gdb) bt
#0 0x0000000000478fd0 in std::_Hashtable<std::tuple<std::string, std::string>, std::pair<std::tuple<std::string, std::string> const, std::function<void (std::shared_ptr<core::dbus::Message> const&)> >, std::allocator<std::pair<std::tuple<std::string, std::string> const, std::function<void (std::shared_ptr<core::dbus::Message> const&)> > >, std::__detail::_Select1st, std::equal_to<std::tuple<std::string, std::string> >, std::hash<std::tuple<std::string, std::string> >, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<true, false, true> >::_M_find_before_node(unsigned long, std::tuple<std::string, std::string> const&, unsigned long) const (this=0x693ab0, __n=3466715, __k=..., __code=14562117148223712363)
    at /usr/include/c++/4.8/bits/hashtable.h:1159
#1 0x0000000000476faa in std::_Hashtable<std::tuple<std::string, std::string>, std::pair<std::tuple<std::string, std::string> const, std::function<void (std::shared_ptr<core::dbus::Message> const&)> >, std::allocator<std::pair<std::tuple<std::string, std::string> const, std::function<void (std::shared_ptr<core::dbus::Message> const&)> > >, std::__detail::_Select1st, std::equal_to<std::tuple<std::string, std::string> >, std::hash<std::tuple<std::string, std::string> >, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<true, false, true> >::_M_find_node(unsigned long, std::tuple<std::string, std::string> const&, unsigned long) const (this=0x693ab0, __bkt=3466715, __key=..., __c=14562117148223712363) at /usr/include/c++/4.8/bits/hashtable.h:604
#2 0x000000000047724c in std::__detail::_Map_base<std::tuple<std::string, std::string>, std::pair<std::tuple<std::string, std::string> const, std::function<void (std::shared_ptr<core::dbus::Message> const&)> >, std::allocator<std::pair<std::tuple<std::string, std::string> const, std::function<void (std::shared_ptr<core::dbus::Message> const&)> > >, std::__detail::_Select1st, std::equal_to<std::tuple<std::string, std::string> >, std::hash<std::tuple<std::string, std::string> >, std::__detail::_Mod_range_hashing, std::__detail::_Default_ranged_hash, std::__detail::_Prime_rehash_policy, std::__detail::_Hashtable_traits<true, false, true>, true>::operator[](std::tuple<std::string, std::string> const&) (this=0x693ab0, __k=...) at /usr/include/c++/4.8/bits/hashtable_policy.h:489
#3 0x00000000004751b1 in std::unordered_map<std::tuple<std::string, std::string>, std::function<void (std::shared_ptr<core::dbus::Message> const&)>, std::hash<std::tuple<std::string, std::string> >, std::equal_to<std::tuple<std::string, std::string> >, std::allocator<std::pair<std::tuple<std::string, std::string> const, std::function<void (std::shared_ptr<core::dbus::Message> const&)> > > >::operator[](std::tuple<std::string, std::string> const&) (this=0x693ab0, __k=...) at /usr/include/c++/4.8/bits/unordered_map.h:596
#4 0x000000000047351b in core::dbus::MessageRouter<std::tuple<std::string, std::string> >::install_route(std::tuple<std::string, std::string> const&, std::function<void (std::shared_ptr<core::dbus::Message> const&)>) (this=0x693a68, key=..., handler=...) at /usr/include/core/dbus/message_router.h:69
#5 0x0000000000475882 in core::dbus::Signal<org::gnome::SettingsDaemon::MediaKeys::Signals::MediaPlayerKeyPressed, std::tuple<std::string, std::string> >::Signal (this=0x691dd0, parent=..., interface=...,
    name=...) at /usr/include/core/dbus/impl/signal.h:290
#6 0x0000000000474208 in core::dbus::Signal<org::gnome::SettingsDaemon::MediaKeys::Signals::MediaPlayerKeyPressed, std::tuple<std::string, std::string> >::make_signal (parent=..., interface=..., name=...)
    at /usr/include/core/dbus/impl/signal.h:268
#7 0x0000000000471ab0 in core::dbus::Object::get_signal<org::gnome::SettingsDaemon::MediaKeys::Signals::MediaPlayerKeyPressed> (this=0x693a40) at /usr/include/core/dbus/impl/object.h:184
#8 0x000000000046dd6b in main () at /home/bohrarper/src/dbus/dbus.cpp:61

[Pär Bohrarper (par-bohrarper-gmail)]

This commit has commented out a similar thing in one of the examples, without any explanation as to why:

http://bazaar.launchpad.net/~phablet-team/dbus-cpp/trunk/revision/17#examples/ofono/main.cpp

[Pär Bohrarper (bohrarper)]

Just wanted to comment with this account that I'm doing this for the new Spotify beta desktop client, which is not yet available for Linux partly due to missing features like this.