cpython/Misc/gdbinit

# -*- ksh -*-
#
# If you use the GNU debugger gdb to debug the Python C runtime, you
# might find some of the following commands useful.  Copy this to your
# ~/.gdbinit file and it'll get loaded into gdb automatically when you
# start it up.  Then, at the gdb prompt you can do things like:
#
#    (gdb) pyo apyobjectptr
#    <module 'foobar' (built-in)>
#    refcounts: 1
#    address    : 84a7a2c
#    $1 = void
#    (gdb)

# Prints a representation of the object to stderr, along with the
# number of reference counts it current has and the hex address the
# object is allocated at.  The argument must be a PyObject*
define pyo
print _PyObject_Dump($arg0)
end

# Prints a representation of the object to stderr, along with the
# number of reference counts it current has and the hex address the
# object is allocated at.  The argument must be a PyGC_Head*
define pyg
print _PyGC_Dump($arg0)
end

# print the local variables of the current frame
define pylocals
    set $_i = 0
    while $_i < f->f_nlocals
	if f->f_localsplus + $_i != 0
	    set $_names = co->co_varnames
	    set $_name = PyString_AsString(PyTuple_GetItem($_names, $_i))
	    printf "%s:\n", $_name
	    # side effect of calling _PyObject_Dump is to dump the object's
	    # info - assigning just prevents gdb from printing the
	    # NULL return value
	    set $_val = _PyObject_Dump(f->f_localsplus[$_i])
	end
        set $_i = $_i + 1
    end
end

# print the current frame
define pyframe
    set $__fn = PyString_AsString(co->co_filename)
    set $__n = PyString_AsString(co->co_name)
    printf "%s (%d): %s\n",  $__fn, f->f_lineno, $__n
    pylocals
end

# Here's a somewhat fragile way to print the entire Python stack from gdb.
# It's fragile because the tests for the value of $pc depend on the layout
# of specific functions in the C source code.

# Explanation of while and if tests: We want to pop up the stack until we
# land in Py_Main (this is probably an incorrect assumption in an embedded
# interpreter, but the test can be extended by an interested party).  If
# Py_Main <= $pc <= Py_GetArgcArv is true, $pc is in Py_Main(), so the while
# tests succeeds as long as it's not true.  In a similar fashion the if
# statement tests to see if we are in eval_frame().

# print the entire Python call stack
define pystack
    while $pc < Py_Main || $pc > Py_GetArgcArgv
        if $pc > PyEval_EvalFrame && $pc < PyEval_EvalCodeEx
	    pyframe
        end
        up-silently 1
    end
    select-frame 0
end