#180 Win32 PCriticalSection problem on exit (solved)

[Michael Rickmann]

Win32 Ekiga stable crashes on exit under Win Vista with service pack 2. The gdb backtrace shows

Program received signal SIGSEGV, Segmentation fault.
[Switching to thread 3916.0xf00]
0x00000000 in ?? ()
....
Thread 3 (thread 3916.0xf00):
#0 0x00000000 in ?? ()
#1 0x0080af85 in PWaitAndSignal::PWaitAndSignal (this=0xa70f5c0,
sem=@0xb0f0b8, wait=true)
at /home/mrickma/src/ekiga-stable/ekiga_build-3.2.5/ptlib-2.6.4/include/ptlib/psync.h:103
#2 0x00776b00 in PIPSocket::Address::AsString (this=0x9456598,
bracketIPv6=true) at ptlib/common/sockets.cxx:1894
#3 0x00501ee9 in OpalTransportAddress::OpalTransportAddress (this=0xa70f990,
addr=@0x9456598, port=5060, proto=0xa68f23 "udp$")
at /home/mrickma/src/ekiga-stable/ekiga_build-3.2.5/opal-3.6.4/src/opal/transports.cxx:98
#4 0x00502045 in OpalTransportIP::GetRemoteAddress (this=0x9456448)
at /home/mrickma/src/ekiga-stable/ekiga_build-3.2.5/opal-3.6.4/src/opal/transports.cxx:955
#5 0x0051f328 in SIPEndPoint::NATBindingRefresh (this=0x94f1ec0)
at /home/mrickma/src/ekiga-stable/ekiga_build-3.2.5/opal-3.6.4/src/sip/sipep.cxx:198
#6 0x00910b7c in SIPEndPoint::NATBindingRefresh_PNotifier::Call (
this=0x94ee0e8, note=@0x94f22d8, extra=1)
at /home/mrickma/src/ekiga-stable/ekiga_build-3.2.5/opal-3.6.4/include/sip/sipep.h:808
#7 0x00960473 in PNotifier::operator() (this=0x94f22e8, notifier=@0x94f22d8,
extra=1)
at /home/mrickma/src/ekiga-stable/ekiga_build-3.2.5/ptlib-2.6.4/include/ptlib/notifier.h:125
#8 0x0074779e in PTimer::OnTimeout (this=0x94f22d8)
at ptlib/common/osutils.cxx:797
#9 0x00747711 in PTimer::Process (this=0x94f22d8, delta=@0xa70fcc8,
minTimeLeft=@0xa70fcb8) at ptlib/common/osutils.cxx:831
#10 0x00748e3f in PTimerList::Process (this=0xb0c1e8)
at ptlib/common/osutils.cxx:958
#11 0x00754d5e in PProcess::HouseKeepingThread::Main (this=0x94e2d80)
at ptlib/msos/win32.cxx:1112
#12 0x00756cd6 in PThread::MainFunction (threadPtr=0x94e2d80)
at ptlib/msos/win32.cxx:707
#13 0x772f2599 in wcstombs () from C:\Windows\system32\msvcrt.dll
#14 0x772f26b3 in msvcrt!_beginthreadex () from C:\Windows\system32\msvcrt.dll
#15 0x760ed0e9 in KERNEL32!AcquireSRWLockExclusive ()
from C:\Windows\system32\kernel32.dll
#16 0x777919bb in ntdll!RtlInitializeNtUserPfn ()
from C:\Windows\system32\ntdll.dll
#17 0x7779198e in ntdll!RtlInitializeNtUserPfn ()
from C:\Windows\system32\ntdll.dll
#18 0x00000000 in ?? ()

The problem lies in " static PCriticalSection x; ". To clarify what happens I disassembled socket.o. This is the snipped showing the constructor
PWaitAndSignal::PWaitAndSignal(PSync const&, bool) :

00006940 push ebp
00006941 mov ebp, esp
00006943 sub esp, 8
00006946 mov eax, [ebp+arg_8]
00006949 mov [ebp+var_4], al
0000694C mov edx, [ebp+arg_0]
0000694F mov eax, [ebp+arg_4]
00006952
00006952 mov [edx], eax
00006954 cmp [ebp+var_4], 0
00006958 jz short locret_6974
0000695A mov eax, [ebp+arg_0]
0000695D mov eax, [eax]
0000695F mov eax, [eax]
00006961 add eax, 28h ; '('
00006964 mov edx, [eax]
00006966 mov eax, [ebp+arg_0]
00006969 mov eax, [eax]
0000696B sub esp, 0Ch
0000696E push eax
0000696F call edx
00006971 add esp, 10h
00006974
00006974 locret_6974:
00006974 leave
00006975 retn

As ckecked with gdb, through the " call edx " the ::EnterCriticalSection(&criticalSection); of include/ptlib/msos/ptlib/ptlib.inl is reached during normal oparation, i.e. before Ekiga exits. On exit however, the " call edx " produces above error indicating that PINLINE void PCriticalSection::Wait(), which is not inline but lies somewhere else in memory has been cleaned up.
This can be solved by using a dynamic PCriticalSection object at sockets.cxx:1894 ommiting the keyword static. My ptlib_critsec.diff limits that to Mingw and Cygwin as it may be really a compiler issue mixing up dynamic (through PMutex) and static allocations of the PCriticalSection functions.
Our next problem, stuck on exit under Vista, becomes accessible now.
Regards
Michael

[Michael Rickmann]

use dynamic PCriticalSection in sockets.cxx for Mingw and Cygwin