How to script gdb (with python)? Example add breakpoints, run, what breakpoint did we hit?

I'm trying to create a little unit test with gdb, for a embedded mcu that is controlled by OpenOCD (that gives me control over my target via a gdb server).

So I would like to automate this with some scripting of gdb.

I would like to write some kind of script for gdb that more or less does this:

1. Add a couple of breakpoints
2. Start the program
3. When we stop, where did it stop (get the frame info)
4. Quit.

Any ideas?

A example on how to do this in python gdb scripting would be nice.

Thanks Johan

---

Note:

Let's say that we have this basic structure, that more or less goes into test_failed() or test_success() depending on what the function start_test() returns.

void test_failed() {    
    while(1);    
}

void test_success() {    
    while(1);    
}

int main(void) {    
    int status = start_test();    

    if( status > 0 ) {    
        test_failed();    
    }    
    test_success();

    while(1);    
}

To do this manually in gdb is very strait forward,

(gdb) break test_success
Breakpoint 1 at 0x20: file src/main.c, line 9.
(gdb) break test_failed
Breakpoint 2 at 0x18: file src/main.c, line 5.
(gdb) cont
Continuing.

Breakpoint 1, test_success () at src/main.c:9
9       while(1);
(gdb) frame
#0  test_success () at src/main.c:9
9       while(1);
(gdb) 

So the next step I tried was to add those gdb commands into a gdb startup script that more or less just looked like this.

break test_success
break test_failed
target remote localhost:3333
cont 
frame

and start it with

arm-none-eabi-gdb --batch --command=commands.gdb main.elf

And this kind of works, but it is not very nice. How do I do this with the "new and cool" python scripts, that gdb seem to support.

FYI recent gdb versions are scriptable in Python. You can call python code from the gdb command line. This opens a whole new world, check the relevant documentation. From the command line run:

 dnf/yum/apt-get install gdb-doc
 info gdb extending python

If you do not like the text-based info browser, here is one (among many?) alternative, graphical browser:

yelp 'info:gdb' # , go to "Extending"

Here is a sample gdb-python script. It attaches gdb to the first "your_program" found running.

#!/usr/bin/python

import subprocess
import string

def backquotes(cmdwords):
        output = subprocess.Popen(cmdwords, stdout=subprocess.PIPE).communicate()[0]
        return output.strip()

pid = backquotes(['pgrep', 'your_program'])

gdb.execute("attach " + str(pid))