简单的C OPENCV IMSHOW示例与分段故障崩溃

Question

（对不起，英语不好，我是德语）

你好程序员，

从理论上讲，这个简单的C OPENCV示例应显示100x100黑色映像，等到按下按下键，将" Still Running！ n"写入错误流中，并使用退出代码退出123。

。

运行此程序时，我会看到黑色图像，直到击中键。似乎一切正常，直到我看终端：

$ ./a.out
still running!
Segmentation fault (Core dumped) #shouldn't happen
$ echo $?
139       #should be 123
$

如果有人可以向我回答以下问题之一，我会很感激： - 为什么此程序会产生细分故障？ - 我怎样才能解决这个问题？ - 源代码有问题吗？如果没有，哪个库/程序负责此错误？

我能听到您的尖叫声："但是，只有在召集出口/返回时才崩溃，为什么要在乎？如果程序正常退出或崩溃，那不会有区别。"您是对的，但我担心导致该程序崩溃的同一错误在退出时可能会导致程序在运行/导致其他奇怪的问题时崩溃。

#include <opencv2/opencv.hpp>
#include <iostream>
int main(void) {
    {
        cv::Mat test(100, 100, CV_8UC1, cv::Scalar(0));
        //cv::namedWindow( "testName", cv::WINDOW_NORMAL ); //doesn't help
        //cv::namedWindow( "testName", cv::WINDOW_OPENGL ); //doesn't help
        cv::imshow( "testName", test );
        cv::waitKey(0);
        //cv::destroyAllWindows(); //doesn't help
    }
    std::cerr << "still running!n";
    return 123;
}

汇编：

$ g++ `pkg-config --cflags --libs opencv` main.cpp

或

$ g++ -lopencv_core -lopencv_highgui main.cpp

有关我的PC的一些其他信息：

OS：Linux（Fedora 25）

$ cat/proc/proces

Linux版本4.8.14-300.fc25.x86_64（[e-mail]）（GCC版本6.2.1 20160916（Red Hat 6.2.1-2）（GCC）＃1 SMP Mon Dec）12 16:31:04 UTC 2016

OPENCV已安装了以下命令：dnf install -y opencv*

输入DNF删除OpenCV并击中选项卡会产生以下输出：

opencv-3.1.0-8.fc25.x86_64             opencv-devel-3.1.0-8.fc25.x86_64
opencv-contrib-3.1.0-8.fc25.x86_64     opencv-devel-docs-3.1.0-8.fc25.noarch
opencv-core-3.1.0-8.fc25.x86_64        opencv-python-3.1.0-8.fc25.x86_64

更新：

$ valgrind ./a.out
==24083== Memcheck, a memory error detector
==24083== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==24083== Using Valgrind-3.12.0 and LibVEX; rerun with -h for copyright info
==24083== Command: ./a.out
==24083== 
^C==24083== 
==24083== Process terminating with default action of signal 2 (SIGINT)
==24083==    at 0x401B4B5: open (in /usr/lib64/ld-2.24.so)
==24083==    by 0x4005547: open_verify.constprop.7 (in /usr/lib64/ld-2.24.so)
==24083==    by 0x40090BF: _dl_map_object (in /usr/lib64/ld-2.24.so)
==24083==    by 0x400DDFF: openaux (in /usr/lib64/ld-2.24.so)
==24083==    by 0x4010873: _dl_catch_error (in /usr/lib64/ld-2.24.so)
==24083==    by 0x400E44D: _dl_map_object_deps (in /usr/lib64/ld-2.24.so)
==24083==    by 0x4003146: dl_main (in /usr/lib64/ld-2.24.so)
==24083==    by 0x401991E: _dl_sysdep_start (in /usr/lib64/ld-2.24.so)
==24083==    by 0x4004F67: _dl_start (in /usr/lib64/ld-2.24.so)
==24083==    by 0x4000CD7: ??? (in /usr/lib64/ld-2.24.so)
==24083== Jump to the invalid address stated on the next line
==24083==    at 0x5A6: ???
==24083==    by 0x4005547: open_verify.constprop.7 (in /usr/lib64/ld-2.24.so)
==24083==    by 0x40090BF: _dl_map_object (in /usr/lib64/ld-2.24.so)
==24083==    by 0x400DDFF: openaux (in /usr/lib64/ld-2.24.so)
==24083==    by 0x4010873: _dl_catch_error (in /usr/lib64/ld-2.24.so)
==24083==    by 0x400E44D: _dl_map_object_deps (in /usr/lib64/ld-2.24.so)
==24083==    by 0x4003146: dl_main (in /usr/lib64/ld-2.24.so)
==24083==    by 0x401991E: _dl_sysdep_start (in /usr/lib64/ld-2.24.so)
==24083==    by 0x4004F67: _dl_start (in /usr/lib64/ld-2.24.so)
==24083==    by 0x4000CD7: ??? (in /usr/lib64/ld-2.24.so)
==24083==  Address 0x5a6 is not stack'd, malloc'd or (recently) free'd
==24083== 
==24083== 
==24083== Process terminating with default action of signal 11 (SIGSEGV)
==24083==  Bad permissions for mapped region at address 0x5A6
==24083==    at 0x5A6: ???
==24083==    by 0x4005547: open_verify.constprop.7 (in /usr/lib64/ld-2.24.so)
==24083==    by 0x40090BF: _dl_map_object (in /usr/lib64/ld-2.24.so)
==24083==    by 0x400DDFF: openaux (in /usr/lib64/ld-2.24.so)
==24083==    by 0x4010873: _dl_catch_error (in /usr/lib64/ld-2.24.so)
==24083==    by 0x400E44D: _dl_map_object_deps (in /usr/lib64/ld-2.24.so)
==24083==    by 0x4003146: dl_main (in /usr/lib64/ld-2.24.so)
==24083==    by 0x401991E: _dl_sysdep_start (in /usr/lib64/ld-2.24.so)
==24083==    by 0x4004F67: _dl_start (in /usr/lib64/ld-2.24.so)
==24083==    by 0x4000CD7: ??? (in /usr/lib64/ld-2.24.so)
==24083== 
==24083== HEAP SUMMARY:
==24083==     in use at exit: 0 bytes in 0 blocks
==24083==   total heap usage: 0 allocs, 0 frees, 0 bytes allocated
==24083== 
==24083== All heap blocks were freed -- no leaks are possible
==24083== 
==24083== For counts of detected and suppressed errors, rerun with: -v
==24083== ERROR SUMMARY: 1 errors from 1 contexts (suppressed: 0 from 0)
Segmentation fault (Speicherabzug geschrieben)

更新＃2

$ g++ -g `pkg-config --cflags --libs opencv` main.cpp; gdb a.out
GNU gdb (GDB) Fedora 7.12-29.fc25
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-redhat-linux-gnu".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from a.out...done.
(gdb) run
Starting program: /home/volker/Dropbox/Roboter/eclipse/CVS/source/a.out 
Missing separate debuginfos, use: dnf debuginfo-install glibc-2.24-3.fc25.x86_64
[Thread debugging using libthread_db enabled]
Using host libthread_db library "/lib64/libthread_db.so.1".
[New Thread 0x7fffc86e1700 (LWP 5063)]
[New Thread 0x7fffbd3b9700 (LWP 5072)]
[New Thread 0x7fffb5974700 (LWP 5089)]
[New Thread 0x7fffb5173700 (LWP 5090)]
[New Thread 0x7fffb4972700 (LWP 5091)]
[New Thread 0x7fffa796c700 (LWP 5100)]
still running!
Thread 7 "QDBusConnection" received signal SIGSEGV, Segmentation fault.
[Switching to Thread 0x7fffa796c700 (LWP 5100)]
0x00007fffefa5601d in QObject::disconnect(QObject const*, char const*, QObject const*, char const*) () from /lib64/libQt5Core.so.5
Missing separate debuginfos, use: dnf debuginfo-install LONG LIST OF PACKAGES
(gdb) backtrace
#0  0x00007fffefa5601d in QObject::disconnect(QObject const*, char const*, QObject const*, char const*) () from /lib64/libQt5Core.so.5
#1  0x00007fffbec6bfb0 in QDBusConnectionPrivate::closeConnection() () from /lib64/libQt5DBus.so.5
#2  0x00007fffbec58852 in QDBusConnectionManager::run() () from /lib64/libQt5DBus.so.5
#3  0x00007fffef88b9da in QThreadPrivate::start(void*) () from /lib64/libQt5Core.so.5
#4  0x00007ffff077e6ca in start_thread () from /lib64/libpthread.so.0
#5  0x00007ffff0a9cf6f in clone () from /lib64/libc.so.6
(gdb) 

Answer 1

我用"gdb"和"eclipse-cdt"进行调试。

1. 使用" gdb"运行程序，并使用"dnf debuginfo-install".
安装调试信息
2. 监视"QApplicationPrivate :: app_style"的值和类型。
3. 在" AdwaitSustyLeplugin.cpp"的"StylePlugin :: ~ StylePlugin ()"中设置一个断点。
4. 查看" qlibrary.cpp：bool qlibraryprivate :: unload（unloadflag flag）"在呼叫层次结构视图中。

我确认

"QLibraryPrivate :: unload ()" will destroy "QApplicationPrivate :: app_style".
"QDBusConnectionPrivate :: closeConnection ()"

应在"QLibraryPrivate :: unload ()"之前执行。

另外，我担心"adwaita :: style"类的基类"QCommonStyle"的破坏者不是"virtual"。

我仍在调查。