division by zero

[kdayns]

Iam running libtorrent 13.2 on some ARM SOC and experiencing pretty frequent crashes here:
#0 0xb6a92344 in raise () from /lib/libpthread.so.0
#1 0xb6aa4bc4 in __aeabi_ldiv0 () from /usr/lib/gcc/armv7a-hardfloat-linux-gnueabi/4.6.3/libgcc_s.so.1
#2 0xb6dc1174 in torrent::FileList::chunk_index_size (this=0xd10160, index=0) at file_list.cc:169
#3 0xb6e4f72c in rak::const_mem_fun1<torrent::FileList, unsigned int, unsigned int>::operator() (this=0xd10124, a1=0) at ../../rak/functional.h:543
#4 0xb6e4eac8 in torrent::Delegator::new_chunk (this=0xd100c4, pc=0xee5080, highPriority=true) at delegator.cc:196
#5 0xb6e4e9e8 in torrent::Delegator::delegate_seeder (this=0xd100c4, peerChunks=0xee5080) at delegator.cc:180
#6 0xb6e4e5c8 in torrent::Delegator::delegate (this=0xd100c4, peerChunks=0xee5080, affinity=-1) at delegator.cc:138
#7 0xb6e95e00 in torrent::RequestList::delegate (this=0xee51c8) at request_list.cc:69
#8 0xb6e94ec0 in torrent::PeerConnectionMetadata::try_request_metadata_pieces (this=0xee5060) at peer_connection_metadata.cc:435
#9 0xb6e959f4 in torrent::PeerConnectionMetadata::fill_write_buffer (this=0xee5060) at peer_connection_metadata.cc:314
#10 0xb6e94530 in torrent::PeerConnectionMetadata::event_write (this=0xee5060) at peer_connection_metadata.cc:338
#11 0xb6d9d0fc in torrent::PollEPoll::perform (this=0xb92b88) at poll_epoll.cc:183
#12 0xb6d9d324 in torrent::PollEPoll::do_poll (this=0xb92b88, timeout_usec=437088, flags=0) at poll_epoll.cc:210
#13 0xb6e103bc in torrent::thread_base::event_loop (thread=0xb90c80) at thread_base.cc:145
#14 0x0003ab04 in main (argc=1, argv=0xbe9b9544) at main.cc:872

(gdb) frame 2
#2 0xb6dc1174 in torrent::FileList::chunk_index_size (this=0xd10160, index=0) at file_list.cc:169

(gdb) l
164 return left;
165 }
166
167 uint32_t
168 FileList::chunk_index_size(uint32_t index) const {
169 if (index + 1 != size_chunks() || size_bytes() % chunk_size() == 0)
170 return chunk_size();
171 else
172 return size_bytes() % chunk_size();
173 }
(gdb) call chunk_size()
$1 = 0
(gdb) frame 4
#4 0xb6e4eac8 in torrent::Delegator::new_chunk (this=0xd100c4, pc=0xee5080, highPriority=true) at delegator.cc:196

196 TransferList::iterator itr = m_transfers.insert(Piece(index, 0, m_slotChunkSize(index)), block_size);
(gdb) l
191 uint32_t index = m_slotChunkFind(pc, highPriority);
192
193 if (index == ~(uint32_t)0)
194 return NULL;
195
196 TransferList::iterator itr = m_transfers.insert(Piece(index, 0, m_slotChunkSize(index)), block_size);
197
198 (*itr)->set_by_seeder(pc->is_seeder());
199
200 if (highPriority)
(gdb) p index
$18 = 0
(gdb) p highPriority
$21 = true

(gdb) p pc
$19 = {m_peerInfo = 0xef8570, m_usingCounter = true, m_bitfield = {m_size = 1, m_set = 1, m_data = 0xedc718 "\200\325\247\266\270-\336"}, m_downloadCache = {static num_layers = 8, m_data = 0x0,
m_maxLayerSize = 0, m_index = 241, m_ceiling = 60464, m_layers = {{first = 0, second = 0}, {first = 0, second = 0}, {first = 0, second = 0}, {first = 0, second = 0}, {first = 0, second = 0}, {first = 0,
second = 0}, {first = 0, second = 0}, {first = 0, second = 0}}}, m_uploadQueue = empty std::list, m_cancelQueue = empty std::list, m_haveTimer = {m_time = 1374896674237079}, m_peerRate = {
m_container = std::deque with 0 elements, m_current = 0, m_total = 0, m_span = 600}, m_downloadThrottle = {m_quota = 0, m_listIterator = , m_rate = {m_container = std::deque with 0 elements,
m_current = 0, m_total = 0, m_span = 30}, m_slotActivate = {m_object = 0xee5068, m_function = (void (torrent::SocketBase::)(
torrent::SocketBase * const)) 0xb6e6df18 torrent::SocketBase::receive_throttle_down_activate()}}, m_uploadThrottle = {m_quota = 0, m_listIterator = , m_rate = {m_container = std::deque with 0 elements,
m_current = 0, m_total = 0, m_span = 30}, m_slotActivate = {m_object = 0xee5068, m_function = (void (torrent::SocketBase::*)(
torrent::SocketBase * const)) 0xb6e6df6c torrent::SocketBase::receive_throttle_up_activate()}}}
(gdb)

(gdb) p ((FileList) m_slotChunkSize->m_object)
$15 = {<std::vector<torrent::File*, std::allocatortorrent::File* >> = std::vector of length 1, capacity 1 = {0xd110d0}, static open_no_create = 1, static open_require_all_open = 2, m_data = {m_hash = {
static size_data = 20, m_data = "s\031f\357z\310.\221^\353d\241Uk-\230\347\370\030\363"}, m_completed_bitfield = {m_size = 1, m_set = 0, m_data = 0xd0b210 ""}, m_untouched_bitfield = {m_size = 1,
m_set = 1, m_data = 0xd087b8 "\200\207\320"},
m_high_priority = {<std::vector<std::pair<unsigned int, unsigned int>, std::allocator<std::pair<unsigned int, unsigned int> > >> = std::vector of length 0, capacity 0, },
m_normal_priority = {<std::vector<std::pair<unsigned int, unsigned int>, std::allocator<std::pair<unsigned int, unsigned int> > >> = std::vector of length 1, capacity 1 = {{first = 0,
second = 1}}, }, m_wanted_chunks = 1, m_slot_initial_hash = {std::tr1::_Maybe_unary_or_binary_function = {}, std::tr1::_Function_base = {
static _M_max_size = 8, static _M_max_align = 4, _M_functor = {_M_unused = {_M_object = 0xd11058, _M_const_object = 0xd11058, _M_function_pointer = 0xd11058, _M_member_pointer = (
void (std::tr1::Undefined_class::)(std::tr1::_Undefined_class * const)) 0xd11058, this adjustment 6848476}, _M_pod_data = "X\020\321\000\270\377\320"},
_M_manager = 0x124894 <std::tr1::Function_base::Base_manager<std::tr1::Bind<std::tr1::Mem_fn<void (core::DownloadList::)(core::Download)> (core::DownloadList, core::Download)> >::_M_manager(std::tr1::_Any_data&, std::tr1::_Any_data const&, std::tr1::_Manager_operation)>},
M_invoker = 0x12486c <std::tr1::Function_handler<void (), std::tr1::Bind<std::tr1::Mem_fn<void (core::DownloadList::)(core::Download)> (core::DownloadList, core::Download)> >::_M_invoke(std::tr1::_Any_data const&)>}, m_slot_download_done = {std::tr1::_Maybe_unary_or_binary_function = {}, std::tr1::_Function_base = {static _M_max_size = 8, static _M_max_align = 4,
_M_functor = {_M_unused = {_M_object = 0xd319a0, _M_const_object = 0xd319a0, _M_function_pointer = 0xd319a0, _M_member_pointer = (void (std::tr1::Undefined_class::)(
std::tr1::_Undefined_class * const)) 0xd319a0, this adjustment 6848476}, _M_pod_data = "\240\031\323\000\270\377\320"},
_M_manager = 0x124894 <std::tr1::_Function_base::_Base_manager<std::tr1::Bind<std::tr1::Mem_fn<void (core::DownloadList::)(core::Download)> (core::DownloadList, core::Download)> >::_M_manager(std::tr1::_Any_data&, std::tr1::_Any_data const&, std::tr1::_Manager_operation)>},
_M_invoker = 0x12486c <std::tr1::_Function_handler<void (), std::tr1::Bind<std::tr1::Mem_fn<void (core::DownloadList::)(core::Download)> (core::DownloadList, core::Download)> >::_M_invoke(std::tr1::_Any_data const&)>}, m_slot_partially_done = {std::tr1::_Maybe_unary_or_binary_function = {}, std::tr1::_Function_base = {static _M_max_size = 8, static _M_max_align = 4,
_M_functor = {_M_unused = {_M_object = 0xa7d0b5e3, _M_const_object = 0xa7d0b5e3, _M_function_pointer = 0xa7d0b5e3, _M_member_pointer = &virtual table offset -1479494173, this adjustment 328511988},
_M_pod_data = "\343\265\320\247\351c)'"}, _M_manager = 0x0}, _M_invoker = 0x6421c774},
m_slot_partially_restarted = {std::tr1::_Maybe_unary_or_binary_function = {}, std::tr1::_Function_base = {static _M_max_size = 8, static _M_max_align = 4, _M_functor = {
_M_unused = {_M_object = 0xb1f78952, _M_const_object = 0xb1f78952, _M_function_pointer = 0xb1f78952, _M_member_pointer = &virtual table offset -1309177518, this adjustment 802265347},
M_pod_data = "R\211\367\261\a2\243"}, _M_manager = 0x0}, _M_invoker = 0x34b64eba}}, m_isOpen = true, m_torrentSize = 0, m_chunkSize = 0, m_maxFileSize = 137438953472, m_rootDir = "/download",
m_indirectLinks = std::vector of length 1, capacity 2 = {"/download"}, m_isMultiFile = false, m_frozenRootDir = "/download"}

(gdb) p ((((FileList*) m_slotChunkSize->m_object))[0])
$17 = {static flag_active = 1, static flag_create_queued = 2, static flag_resize_queued = 4, static flag_fallocate = 8, static flag_previously_created = 16, static flag_prioritize_first = 32,
static flag_prioritize_last = 64, m_fd = 8, m_protection = 1, m_flags = 21,
m_path = {<std::vector<std::basic_string<char, std::char_traits, std::allocator >, std::allocator<std::basic_string<char, std::char_traits, std::allocator > > >> = std::vector of length 1, capacity 1 = {"731966EF7AC82E915EEB64A1556B2D98E7F818F3.meta"}, m_encoding = ""}, m_frozenPath = "/download/731966EF7AC82E915EEB64A1556B2D98E7F818F3.meta", m_offset = 0, m_size = 0,
m_lastTouched = 1374896674479091, m_range = {first = 0, second = 0}, m_completed = 0, m_priority = torrent::PRIORITY_NORMAL, m_matchDepthPrev = 0, m_matchDepthNext = 0}

If you need more info just tell what to look up, this torrent is probably added from magnet link.

[kdayns]

I may be wrong, but I think I tracked that the only way to get invalid(0) chunk_size is thru this function call path:
DownloadMain::set_metadata_size(size)
file_list()->reset_filesize(size);

I will try to reproduce with enabled logging.

[kdayns]

I was rigth, got it again, with logging enabled, and last lines read:
1377651261 I 731966EF7AC82E915EEB64A1556B2D98E7F818F3->file_list: Resetting torrent size: size:0.
1377651261 I 731966EF7AC82E915EEB64A1556B2D98E7F818F3->file_list: Closing.
1377651261 I 731966EF7AC82E915EEB64A1556B2D98E7F818F3->file_list: Opening.

[rakshasa]

Closing as the version is too old