Python API: Getting symbol by address

Python API: Getting symbol by address

[Roman Popov]

Hello,
I have collection in C++ that stores pointers to functions and methods. I
want to pretty-print pointed method and functions names.

It is possible using GDB shell, for example:

(gdb) info symbol 0x405ece

top::test_thread() in section .text of test_procs


However I found no way to do the same using Python API.  Why such
limitation?

P/S Same question on stackoverflow :
https://stackoverflow.com/questions/47916564/gdb-python-api-getting-symbol-name-from-address

Thanks,
Roman

Re: Python API: Getting symbol by address

[Simon Marchi]

On 2017-12-21 13:20, Roman Popov wrote:
> Hello,
> I have collection in C++ that stores pointers to functions and methods. 
> I
> want to pretty-print pointed method and functions names.
> 
> It is possible using GDB shell, for example:
> 
> (gdb) info symbol 0x405ece
> 
> top::test_thread() in section .text of test_procs
> 
> 
> However I found no way to do the same using Python API.  Why such
> limitation?
> 
> P/S Same question on stackoverflow :
> https://stackoverflow.com/questions/47916564/gdb-python-api-getting-symbol-name-from-address
> 
> Thanks,
> Roman

Hi Roman,

As most things in the Python API (and GDB in general), it's likely 
because no one took the time to do it.  I don't see any technical reason 
not to have it.  If you take a shot at writing a patch for this, feel 
free to ask if you are blocked.

Thanks,

Simon

Re: Python API: Getting symbol by address

[Roman Popov]

Thanks, so it is just not implemented yet.
Unfortunately I can't quickly write a patch myself because I'm not familiar
with gdb codebase. I don't even know how debuggers work to be honest .

I've noticed that GDB can pretty-print function/method pointer values like
this:

print ( some_func_ptr_gdbvalue )
>>> (void (*)(int, int)) 0x4049f7 <test(int, int)>

So I've unblocked myself by this ugly text parsing workaround:

s = str (some_func_ptr_gdbvalue)
symbol_name = s[s.find("<") + 1 : s.rfind(">")]
gdb_symbol = gdb.lookup_symbol(symbol_name)


2017-12-21 14:24 GMT-08:00 Simon Marchi <simon.marchi@polymtl.ca>:

> On 2017-12-21 13:20, Roman Popov wrote:
>
>> Hello,
>> I have collection in C++ that stores pointers to functions and methods. I
>> want to pretty-print pointed method and functions names.
>>
>> It is possible using GDB shell, for example:
>>
>> (gdb) info symbol 0x405ece
>>
>> top::test_thread() in section .text of test_procs
>>
>>
>> However I found no way to do the same using Python API.  Why such
>> limitation?
>>
>> P/S Same question on stackoverflow :
>> https://stackoverflow.com/questions/47916564/gdb-python-api-
>> getting-symbol-name-from-address
>>
>> Thanks,
>> Roman
>>
>
> Hi Roman,
>
> As most things in the Python API (and GDB in general), it's likely because
> no one took the time to do it.  I don't see any technical reason not to
> have it.  If you take a shot at writing a patch for this, feel free to ask
> if you are blocked.
>
> Thanks,
>
> Simon
>