Crash on beginning certain streams

[cache-return]

This is ncmpc 0.38. I pulled from git after commit fb34258. I can reliably reproduce by loading https://direct.radiofrance.fr/live/franceinter-midfi.mp3. I was unable to reproduce over SSH in a reasonable sized window, but it crashes on a very small screen (a 20x9 xterm) with high consistency.

--Backtrace follows--

#0 __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
#1 0xb6bc2230 in __GI_abort () at abort.c:79
#2 0xb6bcfbb8 in __assert_fail_base (fmt=0xb6cd66b0 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n",
assertion=0x98f14 "basic.IsDefined()", assertion@entry=0xb6f69cb0 "\001", file=0x98edc "../src/hscroll.cxx",
file@entry=0x990f4 <hscroll::Paint() const::PRETTY_FUNCTION> "void hscroll::Paint() const", line=66,
line@entry=3066914480,
function=function@entry=0x990f4 <hscroll::Paint() const::PRETTY_FUNCTION> "void hscroll::Paint() const")
at assert.c:92
#3 0xb6bcfc6c in __GI___assert_fail (assertion=0xb6f69cb0 "\001",
file=0x990f4 <hscroll::Paint() const::PRETTY_FUNCTION> "void hscroll::Paint() const", line=3066914480,
function=0x990f4 <hscroll::Paint() const::PRETTY_FUNCTION> "void hscroll::Paint() const") at assert.c:101
#4 0x00065b54 in hscroll::Paint (this=0xbee09390) at ../src/hscroll.cxx:66
#5 0x00065fcc in hscroll::TimerCallback (this=0xbee09390, error=...) at ../src/hscroll.cxx:32
#6 0x00066fc4 in std::__invoke_impl<void, void (hscroll::&)(boost::system::error_code const&) noexcept, hscroll&, boost::system::error_code const&>(std::__invoke_memfun_deref, void (hscroll::&)(boost::system::error_code const&) noexcept, hscroll&, boost::system::error_code const&) (__f=
@0xbee09070: (void (hscroll::)(class hscroll * const, const class boost::system::error_code &)) 0x65f94 <hscroll::TimerCallback(boost::system::error_code const&)>, __t=@0xbee09078: 0xbee09390, __args#0=...)
at /usr/include/c++/8/bits/invoke.h:73
#7 0x00066ef8 in std::__invoke<void (hscroll::&)(boost::system::error_code const&) noexcept, hscroll*&, boost::system::error_code const&>(void (hscroll::&)(boost::system::error_code const&) noexcept, hscroll&, boost::system::error_code const&) (__fn=
@0xbee09070: (void (hscroll::)(class hscroll * const, const class boost::system::error_code &)) 0x65f94 <hscroll::TimerCallback(boost::system::error_code const&)>, __args#0=@0xbee09078: 0xbee09390, __args#1=...)
at /usr/include/c++/8/bits/invoke.h:95
#8 0x00066dd4 in std::_Bind<void (hscroll::(hscroll*, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>::__call<void, boost::system::error_code const&, 0u, 1u>(std::tuple<boost::system::error_code const&>&&, std::_Index_tuple<0u, 1u>) (this=0xbee09070, __args=...) at /usr/include/c++/8/functional:400
#9 0x00066d50 in std::_Bind<void (hscroll::(hscroll, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>::operator()<boost::system::error_code const&, void>(boost::system::error_code const&) (this=0xbee09070,
__args#0=...) at /usr/include/c++/8/functional:484
#10 0x00066d00 in boost::asio::detail::binder1<std::_Bind<void (hscroll::(hscroll, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>, boost::system::error_code>::operator()() (this=0xbee09070)
at /usr/include/boost/asio/detail/bind_handler.hpp:65
#11 0x00066cc4 in boost::asio::asio_handler_invoke<boost::asio::detail::binder1<std::_Bind<void (hscroll::(hscroll, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>, boost::system::error_code> >(boost::asio::detail::binder1<std::_Bind<void (hscroll::(hscroll, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>, boost::system::error_code>&, ...) (function=...) at /usr/include/boost/asio/handler_invoke_hook.hpp:69
#12 0x00066ca4 in boost_asio_handler_invoke_helpers::invoke<boost::asio::detail::binder1<std::_Bind<void (hscroll::(hscroll, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>, boost::system::error_code>, std::_Bind<void (hscroll::(hscroll, std::_Placeholder<1>))(boost::system::error_code const&) noexcept> >(boost::asio::detail::binder1<std::_Bind<void (hscroll::(hscroll, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>, boost::system::error_code>&, std::_Bind<void (hscroll::(hscroll, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>&) (function=..., context=...) at /usr/include/boost/asio/detail/handler_invoke_helpers.hpp:37
#13 0x00066b24 in boost::asio::detail::handler_work<std::_Bind<void (hscroll::(hscroll, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>, boost::asio::system_executor>::complete<boost::asio::detail::binder1<std::_Bind<void (hscroll::(hscroll, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>, boost::system::error_code> >(boost::asio::detail::binder1<std::_Bind<void (hscroll::(hscroll, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>, boost::system::error_code>&, std::_Bind<void (hscroll::(hscroll, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>&) (this=0xbee09084, function=..., handler=...)
at /usr/include/boost/asio/detail/handler_work.hpp:82
#14 0x0006680c in boost::asio::detail::wait_handler<std::_Bind<void (hscroll::(hscroll, std::_Placeholder<1>))(boost::system::error_code const&) noexcept> >::do_complete(void*, boost::asio::detail::scheduler_operation*, boost::system::error_code const&, unsigned int) (owner=0x1964c90, base=0x196c450)
at /usr/include/boost/asio/detail/wait_handler.hpp:72
#15 0x00024a78 in boost::asio::detail::scheduler_operation::complete (this=0x196c450, owner=0x1964c90, ec=...,
bytes_transferred=0) at /usr/include/boost/asio/detail/scheduler_operation.hpp:40
#16 0x00027ed8 in boost::asio::detail::scheduler::do_run_one (this=0x1964c90, lock=..., this_thread=..., ec=...) at /usr/include/boost/asio/detail/impl/scheduler.ipp:401
#17 0x00027b00 in boost::asio::detail::scheduler::run (this=0x1964c90, ec=...) at /usr/include/boost/asio/detail/impl/scheduler.ipp:154
#18 0x0002814c in boost::asio::io_context::run (this=0xbee09190) at /usr/include/boost/asio/impl/io_context.ipp:62
#19 0x00023bc4 in Instance::Run (this=0xbee09190) at ../src/Instance.cxx:102
#20 0x00018e84 in main (argc=1, argv=0xbee09664) at ../src/Main.cxx:360

[MaxKellermann]

I have seen this bug a few times, but could not reproduce it now. The fix I have just pushed hopefully fixes the problem (a similar change fixed a similar bug a while ago), but I'm not sure. Please check if the crash is gone now.

[cache-return]

Thanks for the update. It still crashes as before. Here is the backtrace from the crash on the most recent build:

#0  __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
#1  0xb6bbc230 in __GI_abort () at abort.c:79
#2  0xb6bc9bb8 in __assert_fail_base (fmt=0xb6cd06b0 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n", 
    assertion=0x99ef0 "basic.IsDefined()", assertion@entry=0xb6f63cb0 "\001", file=0x99eb8 "../src/hscroll.cxx", 
    file@entry=0x9a0d0 <hscroll::Paint() const::__PRETTY_FUNCTION__> "void hscroll::Paint() const", line=66, 
    line@entry=3066889904, 
    function=function@entry=0x9a0d0 <hscroll::Paint() const::__PRETTY_FUNCTION__> "void hscroll::Paint() const")
    at assert.c:92
#3  0xb6bc9c6c in __GI___assert_fail (assertion=0xb6f63cb0 "\001", 
    file=0x9a0d0 <hscroll::Paint() const::__PRETTY_FUNCTION__> "void hscroll::Paint() const", line=3066889904, 
    function=0x9a0d0 <hscroll::Paint() const::__PRETTY_FUNCTION__> "void hscroll::Paint() const") at assert.c:101
#4  0x00065f34 in hscroll::Paint (this=0x167ca48) at ../src/hscroll.cxx:66
#5  0x000663ac in hscroll::TimerCallback (this=0x167ca48, error=...) at ../src/hscroll.cxx:32
#6  0x000673a4 in std::__invoke_impl<void, void (hscroll::*&)(boost::system::error_code const&) noexcept, hscroll*&, boost::system::error_code const&>(std::__invoke_memfun_deref, void (hscroll::*&)(boost::system::error_code const&) noexcept, hscroll*&, boost::system::error_code const&) (__f=
    @0xbeb91070: (void (hscroll::*)(class hscroll * const, const class boost::system::error_code &)) 0x66374 <hscroll::TimerCallback(boost::system::error_code const&)>, __t=@0xbeb91078: 0x167ca48, __args#0=...)
    at /usr/include/c++/8/bits/invoke.h:73
#7  0x000672d8 in std::__invoke<void (hscroll::*&)(boost::system::error_code const&) noexcept, hscroll*&, boost::system::error_code const&>(void (hscroll::*&)(boost::system::error_code const&) noexcept, hscroll*&, boost::system::error_code const&) (__fn=
    @0xbeb91070: (void (hscroll::*)(class hscroll * const, const class boost::system::error_code &)) 0x66374 <hscroll::TimerCallback(boost::system::error_code const&)>, __args#0=@0xbeb91078: 0x167ca48, __args#1=...)
    at /usr/include/c++/8/bits/invoke.h:95
#8  0x000671b4 in std::_Bind<void (hscroll::*(hscroll*, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>::__call<void, boost::system::error_code const&, 0u, 1u>(std::tuple<boost::system::error_code const&>&&, std::_Index_tuple<0u, 1u>) (this=0xbeb91070, __args=...) at /usr/include/c++/8/functional:400
#9  0x00067130 in std::_Bind<void (hscroll::*(hscroll*, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>::operator()<boost::system::error_code const&, void>(boost::system::error_code const&) (this=0xbeb91070, 
    __args#0=...) at /usr/include/c++/8/functional:484
#10 0x000670e0 in boost::asio::detail::binder1<std::_Bind<void (hscroll::*(hscroll*, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>, boost::system::error_code>::operator()() (this=0xbeb91070)
    at /usr/include/boost/asio/detail/bind_handler.hpp:65
#11 0x000670a4 in boost::asio::asio_handler_invoke<boost::asio::detail::binder1<std::_Bind<void (hscroll::*(hscroll*, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>, boost::system::error_code> >(boost::asio::detail::binder1<std::_Bind<void (hscroll::*(hscroll*, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>, boost::system::error_code>&, ...) (function=...) at /usr/include/boost/asio/handler_invoke_hook.hpp:69
#12 0x00067084 in boost_asio_handler_invoke_helpers::invoke<boost::asio::detail::binder1<std::_Bind<void (hscroll::*(hscroll*, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>, boost::system::error_code>, std::_Bind<void (hscroll::*(hscroll*, std::_Placeholder<1>))(boost::system::error_code const&) noexcept> >(boost::asio::detail::binder1<std::_Bind<void (hscroll::*(hscroll*, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>, boost::system::error_code>&, std::_Bind<void (hscroll::*(hscroll*, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>&) (function=..., context=...) at /usr/include/boost/asio/detail/handler_invoke_helpers.hpp:37
#13 0x00066f04 in boost::asio::detail::handler_work<std::_Bind<void (hscroll::*(hscroll*, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>, boost::asio::system_executor>::complete<boost::asio::detail::binder1<std::_Bind<void (hscroll::*(hscroll*, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>, boost::system::error_code> >(boost::asio::detail::binder1<std::_Bind<void (hscroll::*(hscroll*, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>, boost::system::error_code>&, std::_Bind<void (hscroll::*(hscroll*, std::_Placeholder<1>))(boost::system::error_code const&) noexcept>&) (this=0xbeb91084, function=..., handler=...)
    at /usr/include/boost/asio/detail/handler_work.hpp:82
#14 0x00066bec in boost::asio::detail::wait_handler<std::_Bind<void (hscroll::*(hscroll*, std::_Placeholder<1>))(boost::system::error_code const&) noexcept> >::do_complete(void*, boost::asio::detail::scheduler_operation*, boost::system::error_code const&, unsigned int) (owner=0x167ac90, base=0x1681f38)
    at /usr/include/boost/asio/detail/wait_handler.hpp:72
#15 0x00024ab0 in boost::asio::detail::scheduler_operation::complete (this=0x1681f38, owner=0x167ac90, ec=..., 
    bytes_transferred=0) at /usr/include/boost/asio/detail/scheduler_operation.hpp:40
--Type <RET> for more, q to quit, c to continue without paging--c
#16 0x00027f10 in boost::asio::detail::scheduler::do_run_one (this=0x167ac90, lock=..., this_thread=..., ec=...) at /usr/include/boost/asio/detail/impl/scheduler.ipp:401
#17 0x00027b38 in boost::asio::detail::scheduler::run (this=0x167ac90, ec=...) at /usr/include/boost/asio/detail/impl/scheduler.ipp:154
#18 0x00028184 in boost::asio::io_context::run (this=0xbeb91190) at /usr/include/boost/asio/impl/io_context.ipp:62
#19 0x00023bfc in Instance::Run (this=0xbeb91190) at ../src/Instance.cxx:102
#20 0x00018ebc in main (argc=1, argv=0xbeb91664) at ../src/Main.cxx:360

[MaxKellermann]

Sigh. OK, I still can't reproduce it. When you do, please type in gdb: f 4 and p *this, paste the output here.
What do you do when this triggers? Where is the cursor - on that radio station? Does it crash when you start playback with another client? (e.g. another ncmpc process)

[cache-return]

Exactly what I have been doing today (works every time) Hit Enter/start on the France Inter stream, then hit Tab to switch windows. I was getting the same crash in other contexts, but I can't recall them at the moment.

Thread 1 "ncmpc" received signal SIGABRT, Aborted.
__GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:50
50	../sysdeps/unix/sysv/linux/raise.c: No such file or directory.
(gdb) f 4
#4  0x00065f34 in hscroll::Paint (this=0xbec00390) at ../src/hscroll.cxx:66
66		assert(basic.IsDefined());
(gdb) p *this
$1 = {w = 0xa67618, basic = {separator = 0xbc458 <options+200> " *** ", text = "", buffer = "", max_offset = 99, 
    width = 0, offset = 93}, x = 4, y = 0, style = Style::STATUS, attr = 0, 
  timer = {<boost::asio::basic_io_object<boost::asio::detail::deadline_timer_service<boost::asio::detail::chrono_time_traits<std::chrono::_V2::steady_clock, boost::asio::wait_traits<std::chrono::_V2::steady_clock> > >, true>> = {
      service_ = 0xa66008, implementation_ = {<boost::asio::detail::noncopyable> = {<No data fields>}, expiry = {
          __d = {__r = 196642176324383}}, might_have_pending_waits = false, timer_data = {
          op_queue_ = {<boost::asio::detail::noncopyable> = {<No data fields>}, front_ = 0x0, back_ = 0x0}, 
          heap_index_ = 1, next_ = 0x0, prev_ = 0x0}}}, <No data fields>}}

[MaxKellermann]

I found it: a boost::asio timer cannot be canceled properly: https://www.boost.org/doc/libs/1_74_0/doc/html/boost_asio/reference/basic_waitable_timer/cancel/overload1.html

These handlers can no longer be cancelled, and therefore are passed an error code that indicates the successful completion of the wait operation.

I always thought canceled timers would still be invoked, but with operation_aborted, which is what ncmpc checks:

ncmpc/src/hscroll.cxx

Lines 26 to 29 in 6394fa5

	hscroll::TimerCallback(const boost::system::error_code &error) noexcept
	{
	if (error)
	return;

But that's not enough. Timers which are canceled "too late" will be invoked without an error condition, as the Boost documentation says.
I guess it's time to get rid of boost::asio. That's an annoying design.