[mythtv] Ticket #4719: Segfault in CC708Window

[Andrei Tanas]

> Comment(by danielk):
> 
>  andrei, if this happens again, or you still have the core, pls send a
> full
>  backtrace: "thread apply all bt"

There is a problem with either the compiler or GDB for Win32 - often backtraces are not useable at all, and almost always, in case of a segfault, only the backtrace of the current (crashed) thread can be seen properly, all others show a couple of levels of function calls inside CRT and/or Win32 API, and then nothing - no actual application code at all. See an example below.

If somebody knows a workaround for this, I'd be happy to see it.

--------------------------------------------------------------------------------
Program received signal SIGSEGV, Segmentation fault.
0x1049a022 in QMutex::lock (this=0x4702a00) at tools/qmutex_win.cpp:381
381         d->lock();
 (gdb) thread apply all bt

Thread 5 (thread 6848.0x7dc):
#0  0x77973a11 in tan ()
#1  0x00370000 in ?? ()
#2  0x0c1599c0 in ?? ()
#3  0x77958dde in ntdll!RtlCreateQueryDebugBuffer ()
#4  0x0cfbf2c0 in ?? ()
#5  0x77973b66 in tan ()
#6  0x00370000 in ?? ()
#7  0x0c1599c0 in ?? ()
#8  0x77958dde in ntdll!RtlCreateQueryDebugBuffer ()
#9  0x0cfb2b62 in ?? ()
#10 0x00000000 in ?? ()

Thread 4 (thread 6848.0x1bc4):
#0  0x7797ab1d in ntdll!RtlAnsiStringToUnicodeString ()
#1  0x77031330 in KERNEL32!FindAtomA () from C:\Windows\SysWOW64\ddraw.dll
#2  0x00000000 in ?? ()

Thread 3 (thread 6848.0xde8):
#0  0x7797a69d in ntdll!RtlAnsiStringToUnicodeString ()
#1  0x77031220 in KERNEL32!GetConsoleAliasA () from C:\Windows\SysWOW64\ddraw.dll
#2  0x0000026c in ?? ()
#3  0x00000000 in ?? ()

Thread 2 (thread 6848.0x924):
#0  0x7797a715 in ntdll!RtlAnsiStringToUnicodeString ()
#1  0x74ca1b25 in WSOCK32!TransmitFile ()
#2  0x00000238 in ?? ()
#3  0x0c9bffa8 in ?? ()
#4  0x0c9bff9c in ?? ()
#5  0x0c9bff90 in ?? ()
#6  0x00000000 in ?? ()

Thread 1 (thread 6848.0xfd4):
#0  0x1049a022 in QMutex::lock (this=0x4702a00) at tools/qmutex_win.cpp:381
#1  0x086aedd0 in SSDPCache::Lock (this=0x47029b4) at ssdpcache.cpp:213
#2  0x086af0b6 in SSDPCache::Find (this=0x47029b4, sURI=@0x484315c) at ssdpcache.cpp:256
#3  0x045a115f in MythContextPrivate::UPnPautoconf (this=0xc2c3428, milliSeconds=2000)
    at mythcontext.cpp:1339
#4  0x045b5da0 in MythContextPrivate::FindDatabase (this=0xc2c3428, prompt=false, noPrompt=false)
    at mythcontext.cpp:604
#5  0x045b6819 in MythContextPrivate::Init (this=0xc2c3428, gui=true, UPnPclient=0xc2c1c88,
    promptForBackend=false, noPrompt=false) at mythcontext.cpp:541
#6  0x045b74ce in MythContext::Init (this=0xc2c1cb8, gui=true, UPnPclient=0xc2c1c88,
    promptForBackend=false, disableAutoDiscovery=false) at mythcontext.cpp:1558
#7  0x0040a731 in _fu29__gContext () at main.cpp:1170