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Python API questions and use cases
- From: Joel Borggrén-Franck <joel dot borggren dot franck at gmail dot com>
- To: gdb at sourceware dot org
- Date: Wed, 15 Sep 2010 15:43:48 +0200
- Subject: Python API questions and use cases
Hi
I'm testing out the new Python API for GDB, and have a couple of use cases
that I don't know how to solve entirely from python. I hope this is the
right mailing list.
In all these cases I'm working on debugging a core.
1) Getting the value of a global
given:
typedef struct foo {
int bar;
int baz;
} foo;
foo myGlobalFoo;
in some C file, how do I access the value of myGlobalFoo from python?
The only working solution I have at the moment is to escape to gdb-script
with:
gdb.parse_and_eval("myGlobalFoo")
is this intended?
I know I can iterate over symbols in the symbol table, but I haven't found
a way to go from symbol to value.
2) Casts
given that I know that at address 0xdeadbeef there will be a struct of type
foo how do I get that struct (or a pointer to that struct) as a gdb.Value
object?
Currently i have written a cast function:
def cast(type_string, address):
"""Returns a gdb.Value object with type 'type_string' from memory
starting at 'address'."""
return gdb.parse_and_eval("(%s)((void *)%s)" % (type_string, address))
that I think works, but is there some other way?
Another usecase for casts would be if I wanted to mask an address in python,
given:
foo *fooP;
how do I do the equivalent of this in pyhton:
set $check = ((size_t)foo) & 1
I know there is the a cast in the API but that requires that I have a
gdb.Type which I don't know how to get.
I'd be happy to help out adding solutions to these use-cases!
Cheers
Joel