As you know,eclipse IDE has a convenient attached debugging facility for C project.You can see it from the GUI and you can use this facility to debug process that are already in running status,like daemon process..
My question is that when a process just started and I want to debug it from the begining of the process(i.e. from the first line of main function),how I can do it using the IDE?
I know under Windows,there is a tool called gflag,using this tool we can do some configuraitons before starting the process,and when the process is launched,the gflag can detect this and let the debugger tool(e.g. virtual studio) attach the process automatically.
Do not tell me that use sleep fuction.
Check CDT reverse debugging. You will need GDB 7.0 or later for this feature.
Refer
How_do_I_do_Reverse_Debugging
Open source code with eclipse and double click the left of line number to add a break point. Then you can create a session to debug your application
Related
Environment
Qt 5.6.1
Qt Creator 4.0.1
gdb 7.11
Ubuntu 16.04 LTS
Scenario
C: A client application to communicate with M.
M: A manager process to notify L to launch a new process T.
L: A Launcher process to launch new T by forking itself.
T: A new process running in the background.
I am able to run test application and debug the process C in Qt with gdb. But I am not able to debug the T.
Here is the way I tried to debug the T:
Set breakpoints in both C and T;
When the breakpoint is hit. I use Qt menu option "Debug"->"Start Debugging"->"Attach to running application". To try to attach the debugger to the T process.
This is the problem I am having
Instead of hitting the breakpoints that I set in the T. The gdb always hit an invisible breakpoint in function epoll_wait(). After that, if I continue (F5). The application will keep hanging without hitting any further breakpoints in T. Unless I force stop by using the Qt debug option "Stop Debugger". The application is keep waiting. After I stopped the debugger, the C still breaks in the original breakpoint.
The problem with the debugger in Qt
It seems that Qt uses two different debuggers for different processes. I am thinking it might be caused by the C is hanging. So the T process is keep waiting. But I did not set any breakpoints in wrap_epoll_wait() function I am not sure why gdb breaks there. And in the Qt Debugger. I cannot find a way to switch back to C process to let the process to continue to run. (The Qt debugger component "Threads" drop list is disabled by some reason, I can not select a different thread).
The things I tried
Modified the /etc/sysctl.d/10-ptrace.conf set kernel.yama.ptrace_scope value to 0
Turned the debugger option "Tools->Options->Debugger->GDB Extended->Debug all children" on and off in the Qt.
None of above things changed the fact that the debugger is hanging after the debugger breaks in the function wrap_epoll_wait().
My Question
Anyone at good gdb and Qt knowledge could help me? And let me know how the gdb debug multiple processes works in Qt? How to switch the debugger between different processes and why gdb breaks on somewhere I did not set the breakpoint?
Thank you very much,
Rong
Since T created by forking from L. The gdb settings 'set follow-fork-mode' needs to be set to 'child' in Qt creator.
reference:
https://sourceware.org/gdb/onlinedocs/gdb/Forks.html
I'd like to know if anybody had success with debugging postgres through an IDE (NetBeans or Eclipse) by attaching the debugger to the process and still perform step debugging (stop at breakpoints and watch variables).
For most cases, debugging PostgreSQL isn't significantly different to any other server in this regard.
You determine the process ID of the process you wish to examine, then attach the debugger to it and set breakpoints/watchpoints and continue execution. When you hit the break/watch, examine, step, etc as required.
You can SELECT pg_backend_pid() to get the process ID of the current session.
I usually start psql, SELECT pg_backend_pid(), attach gdb, set my breaks/watches, cont, and in my psql session run whatever I expect to trigger my breakpoint/watchpoint. The same principle applies with IDE debuggers (Visual Studio, Eclipse, NetBeans, whatever).
See: the PostgreSQL wiki for some instructions.
How do i apply break point for a c program in microsoft visual c++ editor?
I tired this -
1)apply break point for a particular line in my code
2)open visual studio command prompt.
3)compiled my program using
cl program.c
4)program.exe
Is this the right procedure to follow?
For break points to fire, you have to run the program inside the IDE (Visual C++ editor in your case) wherein you set them, usually using F5.
If you run from a command prompt there is no debugger attached to the process so nothing can detect the breakpoint being hit. You can also attach a debugger to a running process and set breakpoints to fire post facto.
I have been writing and debugging a minifilter on Windows 7 using the IFS Kit for some time now. it finally works, but as I require to add further functionality, I will spend some more days playing with it
what I'm worried about is debugging. until now I have simply built the driver, installed it on a virtual box and tested it by verifying dbg_print statements. I have been using this simple and error prone approach, as I could not find anything about how to debug minifilters more structured and programmatically.
are there any best practice methods to debug minifilters or filters? can visualDDK be used to add (remote) debugging functionality to visual studio for minifilters?
greetings,
curiosity
The Windows DDK includes a copy of windbg which you can use to connect to the VM over a named pipe with the appropriate configuration.
You can do one better by using VirtualKD to get an accelerated channel to talk to the kernel debugger embedded in Windows.
If you want to do debugging using the Visual Studio user interface, you should look at VisualDDK.
Both are powerful tools, but they require a little work to get set up the first time.
I tend to just use WinDBG because it is the easiest thing to set up on random QA machines etc.
But I have used those tools to iterate rapidly during initial development of a project.
Good luck.
Visual Studio does not support debugging in kernel mode. You can use kd or WinDbg, which are both part of the Debugger package included in Windows DDK. This will get you started with debugging:
Configure kernel debugger on VM and attach WinDbg. Instructions are here: http://ndis.com/ndis-debugging/virtual/vmwaresetup.htm.
Build your binaries in debug mode (or in release with full symbols).
Once WinDbg connected, fix up symbols, and source path. Make sure you added location of symbols of your new driver to the symbol path.
Now you can debug similar how you use VS for user mode apps.
I have my SNMP Extension Agent DLL that is called by the Windows SNMP Service (snmp.exe) everytime i do an snmpwalk (another console application) .I want to step into my DLL code that is called from the above Windows
Service. How do i go about doing that?
Thanks
Som
Normally, you'd attach your debugger to the running process that uses your DLL and then interact with the debugger as you'd normally do.
In Visual Studio 2008, you'd do that by using Debug > Attach To Process, then select the correct process. At least that's how I vaguely remember doing it before.
You can attach to running service from visual studio as Timo Geusch suggests. After that you can set a breakpoint in your code. You also can add call to DebugBreak function in the place you want to debug your library. This can help you if the code you want to debug is executed before you can attach to process (if your code executed in handler of service start event for example).
EDIT: You can attach to any service, even if you don't have debugging information for it, but in this case you wouldn't be able to see stack trace above your function call.