Re: [Flightgear-devel] Reproducable crash in SGGeodesy

[<nir...@gm...>]

I got same error while writing a program today and searched for this error. It looked like this was an uncommon error. I had used a custom comparing function (written by me) to sort a stl vector. Later I found that the function was returning wrong value.

I was returning strcmp(a, b) from comparing function, but the currect return value would be return strcmp(a, b) < 0 ? true : false;.

It seems that stl sort function somehow checks for consistency of sorting done in between while sorting the vector and if finds inconsistency then gives this error.

Thanks,
-- Niraj

-- Torsten Dreyer wrote : 
I experience a reproducable crash in the greater London area:
Start at London City Airport (eglc) with any aircraft you like. For 
simplicity, I use the UFO and enable real-weather-fetch, I use the following 
commandline:
fgfs --aircraft=ufo --airport=eglc --fdm=magic --enable-real-weather-fetch

Zoom up to approx 10000ft, fly westbound until passing Tower Bridge initiate a 
shallow 360 to the left and *BANG*

Program received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0xb63e1910 (LWP 8643)]
0x085e9920 in SGGeodesy::SGGeodToCart (geod=@0x31, cart=@0xbfc7d0c0) at 
SGGeodesy.cxx:100
100     SGGeodesy::SGGeodToCart(const SGGeod& geod, SGVec3<double>& cart)
(gdb) bt
#0  0x085e9920 in SGGeodesy::SGGeodToCart (geod=@0x31, cart=@0xbfc7d0c0) at 
SGGeodesy.cxx:100
#1  0x0848d39a in FGPositioned::cart (this=0x21) 
at /usr/local/include/simgear/math/SGVec3.hxx:191
#2  0x0849057f in DistanceOrdering::operator() (this=0xbfc7d138, 
a=@0xbfc7d1c0, b=@0x18b56fcc) at positioned.cxx:221
#3  0x08491b61 in 
std::__unguarded_linear_insert<__gnu_cxx::__normal_iterator<SGSharedPtr<FGPositioned>*, 
std::vector<SGSharedPtr<FGPositioned>, 
std::allocator<SGSharedPtr<FGPositioned> > > >, SGSharedPtr<FGPositioned>, 
DistanceOrdering> (__last={_M_current = 0x18b56fd4}, __val={_ptr = 
0xbfc7d1c0}, __comp=
              {mPos = {<SGVec3Storage<double>> = {<osg::Vec3d> = {_v = 
{3988693.4857778242, 19214.264641430258, 4960318.8364768205}}, <No data 
fields>}, <No data fields>}})
    at /usr/include/c++/4.3/bits/stl_algo.h:1735
#4  0x08492e3e in 
std::__insertion_sort<__gnu_cxx::__normal_iterator<SGSharedPtr<FGPositioned>*, 
std::vector<SGSharedPtr<FGPositioned>, 
std::allocator<SGSharedPtr<FGPositioned> > > >, DistanceOrdering> 
(__first={_M_current = 0x18b56fd0}, __last={_M_current = 0x18b56fe8}, __comp=
              {mPos = {<SGVec3Storage<double>> = {<osg::Vec3d> = {_v = 
{3988693.4857778242, 19214.264641430258, 4960318.8364768205}}, <No data 
fields>}, <No data fields>}})
    at /usr/include/c++/4.3/bits/stl_algo.h:1785
#5  0x08492fb9 in 
std::__final_insertion_sort<__gnu_cxx::__normal_iterator<SGSharedPtr<FGPositioned>*, 
std::vector<SGSharedPtr<FGPositioned>, 
std::allocator<SGSharedPtr<FGPositioned> > > >, DistanceOrdering> 
(__first={_M_current = 0xbfc7d0c0}, __last={_M_current = 0x18b56fe8}, __comp=
              {mPos = {<SGVec3Storage<double>> = {<osg::Vec3d> = {_v = 
{3988693.4857778242, 19214.264641430258, 4960318.8364768205}}, <No data 
fields>}, <No data fields>}})
    at /usr/include/c++/4.3/bits/stl_algo.h:1849
#6  0x0848f25f in sortByDistance (aPos=<value optimized out>, aResult=<value 
optimized out>) at /usr/include/c++/4.3/bits/stl_algo.h:4822
#7  0x0848fcdd in spatialGetClosest (aPos=@0xbfc7d630, aN=1, aCutoffNm=10000, 
aFilter=0xbfc7d64c) at positioned.cxx:328
#8  0x0848fe06 in FGPositioned::findClosest (aPos=@0xbfc7d630, 
aCutoffNm=10000, aFilter=0xbfc7d64c) at positioned.cxx:537
#9  0x084b5a0a in FGAirport::findClosest (aPos=@0xbfc7d630, aCuttofNm=10000, 
filter=0xbfc7d64c) at simple.cxx:242
#10 0x0852f8dd in FGMetarEnvironmentCtrl::update (this=0x1043b5d0, 
delta_time_sec=0.5) at environment_ctrl.cxx:729
#11 0x08629809 in SGSubsystemGroup::Member::update (this=0x1043bec0, 
delta_time_sec=0.041666666666666664) at subsystem_mgr.cxx:306
#12 0x0862c29b in SGSubsystemGroup::update (this=0x1043aa88, 
delta_time_sec=0.041666666666666664) at subsystem_mgr.cxx:159
#13 0x08526f2a in FGEnvironmentMgr::update (this=0x1043aa88, 
dt=0.041666666666666664) at environment_mgr.cxx:258
#14 0x08629809 in SGSubsystemGroup::Member::update (this=0x10463cb8, 
delta_time_sec=0.041666666666666664) at subsystem_mgr.cxx:306
#15 0x0862c29b in SGSubsystemGroup::update (this=0x87a165c, 
delta_time_sec=0.041666666666666664) at subsystem_mgr.cxx:159
#16 0x0806a36b in fgMainLoop () at main.cxx:498
#17 0x080b20ec in fgOSMainLoop () at fg_os_osgviewer.cxx:177
#18 0x08069725 in fgMainInit (argc=3, argv=0xbfc7dd34) at main.cxx:1046
#19 0x080677ea in main (argc=-652280259, argv=0x3fe8fbc2) at bootstrap.cxx:177
(gdb)

This is on OpenSuSE 11.1 with todays FlightGear/SimGear CVS and the 
terragear/SVN synced scenery.

Anybody else gets this?

Torsten


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