Writing Front End for GDB

问题:

I want to write a GUI based debugger wrapped over GDB. Because, I dont want the program to stop after watch points or break points. Instead, it should redirect the details like filename, line number, new value and stuffs to a file and continue execution.

I am pretty bad at scripting. So, I want some starting point to start developing front end for GDB. As far as I googled, this link http://ftp.gnu.org/old-gnu/Manuals/gdb-5.1.1/html_node/gdb_211.html is not much understandable for a beginner in this activity?

Hopefully, I will get help on development in C/C++.

回答1:

For writing a GDB frontend, you indeed want to use the GDB/MI protocol but perhaps read this up-to-date copy instead of the older one you linked to.

Sample GDB/MI session

(Lightly edited version of this section from the GDB manual)

Launching GDB with the MI Command Interpreter

$ gdb -q --interpreter=mi2
=thread-group-added,id="i1"
(gdb)

File /bin/true

-file-exec-and-symbols /bin/true
^done
(gdb) 

Break main

-break-insert main
^done,bkpt={number="1",type="breakpoint",disp="keep",enabled="y",addr="0x00000000004014c0",func="main",file="true.c",fullname="/usr/src/debug/coreutils-8.17/src/true.c",line="59",times="0",original-location="main"}
(gdb) 

Run and Breakpoint Hit

-exec-run
=thread-group-started,id="i1",pid="2275"
=thread-created,id="1",group-id="i1"
^running
*running,thread-id="all"
(gdb) 
=library-loaded,id="/lib64/ld-linux-x86-64.so.2",target-name="/lib64/ld-linux-x86-64.so.2",host-name="/lib64/ld-linux-x86-64.so.2",symbols-loaded="0",thread-group="i1"
=library-loaded,id="/lib64/libc.so.6",target-name="/lib64/libc.so.6",host-name="/lib64/libc.so.6",symbols-loaded="0",thread-group="i1"
=breakpoint-modified,bkpt={number="1",type="breakpoint",disp="keep",enabled="y",addr="0x00000000004014c0",func="main",file="true.c",fullname="/usr/src/debug/coreutils-8.17/src/true.c",line="59",times="1",original-location="main"}
*stopped,reason="breakpoint-hit",disp="keep",bkptno="1",frame={addr="0x00000000004014c0",func="main",args=[{name="argc",value="1"},{name="argv",value="0x7fffffffde98"}],file="true.c",fullname="/usr/src/debug/coreutils-8.17/src/true.c",line="59"},thread-id="1",stopped-threads="all",core="1"
(gdb) 

Continue

-exec-continue
^running
*running,thread-id="1"
(gdb) 
=thread-exited,id="1",group-id="i1"
=thread-group-exited,id="i1",exit-code="0"
*stopped,reason="exited-normally"

Quitting GDB

(gdb) 
-gdb-exit
^exit

Existing GDB/MI Clients

There are several GDB/MI client implementations in C, C++, Java, Python. I'll list a few that I find easy to read:

• The inactive libmigdb project (sample program, public interfaces) -- The good news is that it's an attempt at creating a reusable C library. The bad news is that it's not well maintained, e.g. I think it's missing GDB non-stop mode and catchpoint commands support, features that your use case would likely need.
• python-gdb-mi -- Quite readable if you know Python
• The C++ GDB/MI client code in QtCreator -- Also quite readable though it's written as part of an abstraction layer to support multiple debugger engines.

You might want to also browse this list of GDB frontends.

回答2:

Since you already pointed out the gdb/mi interface maybe an existing solution might give you an idea on how to address your needs. Here is a list of existing interfaces. Look at their approaches and how they address the different issues.

Another approach that might be helpful could be automated sessions. Not to discourage you from writing a gdb gui, but such an automation could be a good start to get a feeling for the steps needed and could maybe also used as a start. Maybe generating a session script and starting gdb with it. gdb -x to load a command file.

Here a link concerning automating: What are the best ways to automate a GDB debugging session?

I hope it helps. Good luck!

回答3:

Though writing new GUI tools gives you more knowledge, I suggest you to take up eclipe and modify according to your needs. It saves lot of your time as well as more flexible.

回答4:

Programming a gdb wrapper to achieve your goal is way to much work.

See how you can execute script on breakpoint hits: gdb scripting: execute commands at selected breakpoint

Also take a look a gdb tracepoints: http://sourceware.org/gdb/onlinedocs/gdb/Tracepoints.html