Stable 2.2 segfault on Linux

[helmchenlord]

Hi I am running Gentoo AMD64, opentracker compiles fine, but starting it ends with a Segmentation Fault.

gdb) r
Starting program: /usr/local/opentrack
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".

Program received signal SIGSEGV, Segmentation fault.
0x00007fffe8aa4f8c in ?? () from /usr/lib64/qt4/libQtTest.so.4

I would like to use Opentrack with the edtracker to play War Thunder.

[T1ckL35]

Do you have any instructions on how you compile this project for linux? (I'm using Ubuntu)
I'm a developer but not of C or compiling programs like this from source.

Any help/pointers would be greatly appreciated

[sthalik]

@helmchenlord show the backtrace, please.

@T1ckL35 Linux is supported only for developer convenience. See FAQ

[T1ckL35]

@sthalik Thanks for pointing it out. I've managed to build it now anyway, just need to get it recognising the webcam.

[helmchenlord]

@sthalik Backtrace as follows:

(gdb) bt
#0 0x00007fffe8aa4f8c in ?? () from /usr/lib64/qt4/libQtTest.so.4
#1 0x00007ffff7de9dca in ?? () from /lib64/ld-linux-x86-64.so.2
#2 0x00007ffff7de9ec5 in ?? () from /lib64/ld-linux-x86-64.so.2
#3 0x00007ffff7ddc11a in ?? () from /lib64/ld-linux-x86-64.so.2
#4 0x0000000000000001 in ?? ()
#5 0x00007fffffffde3b in ?? ()
#6 0x0000000000000000 in ?? ()

[sthalik]

@helmchenlord it doesn't make sense, we don't even use QtTest. Run under valgrind to get a proper backtrace.

[helmchenlord]

This is how I have built opentrack:
git clone -b stable/2.2 https://github.com/opentrack/opentrack.git
cd opentrack
cmake CMakeLists.txt
make
make install

ls -l /usr/local/opentrack
-rwxr-xr-x 1 root root 612024 Jan 13 13:34 /usr/local/opentrack

Here is the output from valgrind:
valgrind --track-fds=yes /usr/local/opentrack
==11727== Memcheck, a memory error detector
==11727== Copyright (C) 2002-2013, and GNU GPL'd, by Julian Seward et al.
==11727== Using Valgrind-3.10.1 and LibVEX; rerun with -h for copyright info
==11727== Command: /usr/local/opentrack
==11727==
==11727==
==11727== Process terminating with default action of signal 11 (SIGSEGV)
==11727== Bad permissions for mapped region at address 0x6C5F950
==11727== at 0x13F56F8C: ??? (in /usr/lib64/qt4/libQtTest.so.4.8.6)
==11727== by 0x400EDA9: call_init.part.0 (dl-init.c:72)
==11727== by 0x400EEA4: call_init (dl-init.c:126)
==11727== by 0x400EEA4: _dl_init (dl-init.c:120)
==11727== by 0x4001119: ??? (in /lib64/ld-2.21.so)
==11727==
==11727== FILE DESCRIPTORS: 4 open at exit.
==11727== Open file descriptor 3: /dev/urandom
==11727== at 0x7392300: __open_nocancel (syscall-template.S:81)
==11727== by 0x1A1E8478: ??? (in /usr/lib64/libgnutls.so.28.41.9)
==11727== by 0x1A1E8A74: ??? (in /usr/lib64/libgnutls.so.28.41.9)
==11727== by 0x1A15C13B: ??? (in /usr/lib64/libgnutls.so.28.41.9)
==11727== by 0x1A1500AD: gnutls_global_init (in /usr/lib64/libgnutls.so.28.41.9)
==11727== by 0x1A130A08: ??? (in /usr/lib64/libgnutls.so.28.41.9)
==11727== by 0x400EDA9: call_init.part.0 (dl-init.c:72)
==11727== by 0x400EEA4: call_init (dl-init.c:126)
==11727== by 0x400EEA4: _dl_init (dl-init.c:120)
==11727== by 0x4001119: ??? (in /lib64/ld-2.21.so)
==11727==
==11727== Open file descriptor 2: /dev/pts/0
==11727==
==11727==
==11727== Open file descriptor 1: /dev/pts/0
==11727==
==11727==
==11727== Open file descriptor 0: /dev/pts/0
==11727==
==11727==
==11727==
==11727== HEAP SUMMARY:
==11727== in use at exit: 130,560 bytes in 879 blocks
==11727== total heap usage: 1,507 allocs, 628 frees, 153,287 bytes allocated
==11727==
==11727== LEAK SUMMARY:
==11727== definitely lost: 0 bytes in 0 blocks
==11727== indirectly lost: 0 bytes in 0 blocks
==11727== possibly lost: 4,676 bytes in 83 blocks
==11727== still reachable: 125,884 bytes in 796 blocks
==11727== suppressed: 0 bytes in 0 blocks
==11727== Rerun with --leak-check=full to see details of leaked memory
==11727==
==11727== For counts of detected and suppressed errors, rerun with: -v
==11727== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
Segmentation fault

[sthalik]

Your Qt installation is messed up. There are many ways to break things on Gentoo.

Edit: according to Valgrind this error happens even before "main".

[sthalik]

I don't think in this state you can even run qtconfig-qt5. Recompile qttest:5 for a start.

[ff2000]

@helmchenlord is using the stable branch. In the CMakeLists.txt you only ask for OpenCV and not OpenCV-3.0. He is using OpenCV-2.4 (which only has Qt4-support), therefor opencv_highgui links against Qt4. opentrack pulls in Qt5, which causes trouble.
I hope the upgrade to OpenCV-3.0 + Qt5-support will fix this issue. Would be great if you could fix the find_package(opencv). At least I think it's not a broken system.

Furthermore please use proper install destinations. install([...] DESTINATION .) will throw everything into CMAKE_INSTALL_PREFIX, which is /usr/local by default (on linux) - not that nice ;) Left-over of the windows origin?

For reference: https://forums.gentoo.org/viewtopic-p-7870194.html#7870194

// edit:
later versions of opencv still support Qt4. Is there a chance to also catch that case in opentracks CMakeLists.txt?

[sthalik]

Furthermore please use proper install destinations

We don't support hier(7) in this build system. You can package everything into $prefix/libexec if you must.

You may also disable qt/gtk/x11 support in opencv completely. opentrack doesn't use it any way.

[sthalik]

Is there a chance to also catch that case in opentracks CMakeLists.txt?

We need to link against highgui. There's no way to use RTLD_DEEPBIND except for dlopen(3) even if that'd help.

What you can do however is build a static library version of opencv specifically for opentrack, from git sources. Point opentrack's cmake cache to it. Then the package version can coexist in case other programs depend on it.

There's one more thing you need to fix, see opencv/cmake/OpenCVFindLibsVideo.cmake:

if(HAVE_LIBV4L1 AND HAVE_LIBV4L2)
  set(HAVE_LIBV4L YES)
else()
  set(HAVE_LIBV4L NO)
endif()

Change that first line to

if(HAVE_LIBV4L2)

Otherwise you'll use an obsolete camera interface that crashes on camera stoppage.

[sthalik]

@ff2000 hier(7) is followed now in unstable.

[sthalik]

For the record, we now don't link in the highgui module at all. If you still have it linked, maybe -Wl,--as-needed will help.

[sthalik]

I just tested a fresh Linux build with shared packaged opencv and it doesn't link in highgui. If it gets linked in, delete the build directory and make a new one. There's sometimes stale data in cmake's cache.

[xx70x]

CMake Error at CMakeLists.txt:1 (project):
No CMAKE_CXX_COMPILER could be found.

Tell CMake where to find the compiler by setting either the environment
variable "CXX" or the CMake cache entry CMAKE_CXX_COMPILER to the full path
to the compiler, or to the compiler name if it is in the PATH.

-- Configuring incomplete, errors occurred!
See also "/tmp/opentrack/CMakeFiles/CMakeOutput.log".
See also "/tmp/opentrack/CMakeFiles/CMakeError.log"

what is missing?

[sthalik]

% which cc
% which c++

If this is a debian-based system, install the build-essentials package.