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Filter Python access with a function.
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JavaScript requests for data from the Python VM can now be filtered by
specifying an access callback function on the Context instance. See the
README or test-access.py tests for API usage.

Thanks to Richard Boulton for the initial patch.
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@davisp
davisp committed Jun 14, 2009
1 parent 44e4423 commit e8e69e9
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Showing 8 changed files with 313 additions and 20 deletions.
32 changes: 28 additions & 4 deletions README.md
View file
Expand Up @@ -137,7 +137,8 @@ Basics
>>> fruit = Orange()
>>> cx.add_global("apple", fruit)
>>> cx.execute('"Show me the " + apple.is_ripe("raisin");')
Show me the ripe raisin
u'Show me the ripe raisin'


Playing with Classes
--------------------
Expand All @@ -151,13 +152,14 @@ Playing with Classes
...
>>> rt = spidermonkey.Runtime()
>>> cx = rt.new_context()
>>> cx.add_global(Monkey)
>>> cx.add_global("Monkey", Monkey)
>>> monkey = cx.execute('var x = new Monkey(); x.baz = "schmammo"; x;')
>>> monkey.baz
'schmammo'
u'schmammo'
>>> monkey.__class__.__name__
'Monkey'


JavaScript Functions
--------------------

Expand All @@ -166,7 +168,29 @@ JavaScript Functions
>>> cx = rt.new_context()
>>> func = cx.execute('function(val) {return "whoosh: " + val;}')
>>> func("zipper!");
'whoosh: zipper!'
u'whoosh: zipper!'


Filtering access to Python
--------------------------

>>> import spidermonkey
>>> rt = spidermonkey.Runtime()
>>> def checker(obj, name):
... return not name.startswith("_")
...
>>> cx = rt.new_context(access=checker)
>>> # Alternatively:
>>> cx.set_access() #doctest: +ELLIPSIS
<function checker at ...>
>>> cx.set_access(checker) #doctest: +ELLIPSIS
<function checker at ...>
>>> cx.add_global("fish", {"gold": "gone", "_old_lady": "huzza"})
>>> cx.execute('fish["_old_lady"];')
Traceback (most recent call last):
...
JSError: Error executing JavaScript.


Previous Authors
================
Expand Down
3 changes: 3 additions & 0 deletions THANKS
View file
Expand Up @@ -27,3 +27,6 @@ Riccardo Pelizzi

Keiji Costantini
* Bug report on the memory limit test.

Richard Boulton
* Initial patch for filtering Python access.
117 changes: 113 additions & 4 deletions spidermonkey/context.c
View file
Expand Up @@ -13,6 +13,9 @@
#include <jsobj.h>
#include <jscntxt.h>

// Forward decl for add_prop
JSBool set_prop(JSContext* jscx, JSObject* jsobj, jsval key, jsval* rval);

JSBool
add_prop(JSContext* jscx, JSObject* jsobj, jsval key, jsval* rval)
{
Expand Down Expand Up @@ -46,6 +49,9 @@ del_prop(JSContext* jscx, JSObject* jsobj, jsval key, jsval* rval)
ret = JS_TRUE;
goto done;
}

// Check access to python land.
if(Context_has_access(pycx, jscx, pycx->global, pykey) <= 0) goto done;

// Bail if the global doesn't have a __delitem__
if(!PyObject_HasAttrString(pycx->global, "__delitem__"))
Expand Down Expand Up @@ -92,6 +98,8 @@ get_prop(JSContext* jscx, JSObject* jsobj, jsval key, jsval* rval)
pykey = js2py(pycx, key);
if(pykey == NULL) goto done;

if(Context_has_access(pycx, jscx, pycx->global, pykey) <= 0) goto done;

pyval = PyObject_GetItem(pycx->global, pykey);
if(pyval == NULL)
{
Expand Down Expand Up @@ -138,6 +146,8 @@ set_prop(JSContext* jscx, JSObject* jsobj, jsval key, jsval* rval)
pykey = js2py(pycx, key);
if(pykey == NULL) goto done;

if(Context_has_access(pycx, jscx, pycx->global, pykey) <= 0) goto done;

pyval = js2py(pycx, *rval);
if(pyval == NULL) goto done;

Expand Down Expand Up @@ -175,6 +185,8 @@ resolve(JSContext* jscx, JSObject* jsobj, jsval key)

pykey = js2py(pycx, key);
if(pykey == NULL) goto done;

if(Context_has_access(pycx, jscx, pycx->global, pykey) <= 0) goto done;

if(!PyMapping_HasKey(pycx->global, pykey))
{
Expand Down Expand Up @@ -275,21 +287,36 @@ Context_new(PyTypeObject* type, PyObject* args, PyObject* kwargs)
Context* self = NULL;
Runtime* runtime = NULL;
PyObject* global = NULL;
PyObject* access = NULL;

char* keywords[] = {"runtime", "glbl", "access", NULL};

if(!PyArg_ParseTuple(
args,
"O!|O",
if(!PyArg_ParseTupleAndKeywords(
args, kwargs,
"O!|OO",
keywords,
RuntimeType, &runtime,
&global
&global,
&access
)) goto error;

if(global == Py_None) global = NULL;
if(access == Py_None) access = NULL;

if(global != NULL && !PyMapping_Check(global))
{
PyErr_SetString(PyExc_TypeError,
"Global handler must provide item access.");
goto error;
}

if(access != NULL && !PyCallable_Check(access))
{
PyErr_SetString(PyExc_TypeError,
"Access handler must be callable.");
goto error;
}

self = (Context*) type->tp_alloc(type, 0);
if(self == NULL) goto error;

Expand Down Expand Up @@ -344,6 +371,9 @@ Context_new(PyTypeObject* type, PyObject* args, PyObject* kwargs)
if(global != NULL) Py_INCREF(global);
self->global = global;

if(access != NULL) Py_INCREF(access);
self->access = access;

// Setup counters for resource limits
self->branch_count = 0;
self->max_time = 0;
Expand Down Expand Up @@ -383,6 +413,7 @@ Context_dealloc(Context* self)
}

Py_XDECREF(self->global);
Py_XDECREF(self->access);
Py_XDECREF(self->objects);
Py_XDECREF(self->classes);
Py_XDECREF(self->rt);
Expand Down Expand Up @@ -473,6 +504,42 @@ Context_rem_global(Context* self, PyObject* args, PyObject* kwargs)
return ret;
}

PyObject*
Context_set_access(Context* self, PyObject* args, PyObject* kwargs)
{
PyObject* ret = NULL;
PyObject* newval = NULL;

if(!PyArg_ParseTuple(args, "|O", &newval)) goto done;
if(newval != NULL && newval != Py_None)
{
if(!PyCallable_Check(newval))
{
PyErr_SetString(PyExc_TypeError,
"Access handler must be callable.");
ret = NULL;
goto done;
}
}

ret = self->access;

if(newval != NULL && newval != Py_None)
{
Py_INCREF(newval);
self->access = newval;
}

if(ret == NULL)
{
ret = Py_None;
Py_INCREF(ret);
}

done:
return ret;
}

PyObject*
Context_execute(Context* self, PyObject* args, PyObject* kwargs)
{
Expand Down Expand Up @@ -594,6 +661,12 @@ static PyMethodDef Context_methods[] = {
METH_VARARGS,
"Remove a global object in the JS VM."
},
{
"set_access",
(PyCFunction)Context_set_access,
METH_VARARGS,
"Set the access handler for wrapped python objects."
},
{
"execute",
(PyCFunction)Context_execute,
Expand Down Expand Up @@ -663,6 +736,42 @@ PyTypeObject _ContextType = {
Context_new, /*tp_new*/
};

int
Context_has_access(Context* pycx, JSContext* jscx, PyObject* obj, PyObject* key)
{
PyObject* tpl = NULL;
PyObject* tmp = NULL;
int res = -1;

if(pycx->access == NULL)
{
res = 1;
goto done;
}

tpl = Py_BuildValue("(OO)", obj, key);
if(tpl == NULL) goto done;

tmp = PyObject_Call(pycx->access, tpl, NULL);
res = PyObject_IsTrue(tmp);

done:
Py_XDECREF(tpl);
Py_XDECREF(tmp);

if(res < 0)
{
PyErr_Clear();
JS_ReportError(jscx, "Failed to check python access.");
}
else if(res == 0)
{
JS_ReportError(jscx, "Python access prohibited.");
}

return res;
}

PyObject*
Context_get_class(Context* cx, const char* key)
{
Expand Down
3 changes: 3 additions & 0 deletions spidermonkey/context.h
View file
Expand Up @@ -18,6 +18,7 @@ typedef struct {
PyObject_HEAD
Runtime* rt;
PyObject* global;
PyObject* access;
JSContext* cx;
JSObject* root;
PyDictObject* classes;
Expand All @@ -31,6 +32,8 @@ typedef struct {
PyObject* Context_get_class(Context* cx, const char* key);
int Context_add_class(Context* cx, const char* key, PyObject* val);

int Context_has_access(Context*, JSContext*, PyObject*, PyObject*);

int Context_has_object(Context* cx, PyObject* val);
int Context_add_object(Context* cx, PyObject* val);
int Context_rem_object(Context* cx, PyObject* val);
Expand Down
21 changes: 21 additions & 0 deletions spidermonkey/pyobject.c
View file
Expand Up @@ -58,6 +58,8 @@ js_del_prop(JSContext* jscx, JSObject* jsobj, jsval key, jsval* val)
pykey = js2py(pycx, key);
if(pykey == NULL) goto error;

if(Context_has_access(pycx, jscx, pyobj, pykey) <= 0) goto error;

if(PyObject_DelItem(pyobj, pykey) < 0)
{
PyErr_Clear();
Expand Down Expand Up @@ -101,6 +103,8 @@ js_get_prop(JSContext* jscx, JSObject* jsobj, jsval key, jsval* val)
pykey = js2py(pycx, key);
if(pykey == NULL) goto done;

if(Context_has_access(pycx, jscx, pyobj, pykey) <= 0) goto done;

// Yeah. It's ugly as sin.
if(PyString_Check(pykey) || PyUnicode_Check(pykey))
{
Expand Down Expand Up @@ -177,6 +181,8 @@ js_set_prop(JSContext* jscx, JSObject* jsobj, jsval key, jsval* val)
goto error;
}

if(Context_has_access(pycx, jscx, pyobj, pykey) <= 0) goto error;

pyval = js2py(pycx, *val);
if(pyval == NULL)
{
Expand Down Expand Up @@ -262,6 +268,7 @@ js_call(JSContext* jscx, JSObject* jsobj, uintN argc, jsval* argv, jsval* rval)
PyObject* pyobj = NULL;
PyObject* tpl = NULL;
PyObject* ret = NULL;
PyObject* attrcheck = NULL;
JSBool jsret = JS_FALSE;

pycx = (Context*) JS_GetContextPrivate(jscx);
Expand All @@ -279,6 +286,12 @@ js_call(JSContext* jscx, JSObject* jsobj, uintN argc, jsval* argv, jsval* rval)
goto error;
}

// Use '__call__' as a notice that we want to execute a function.
attrcheck = PyString_FromString("__call__");
if(attrcheck == NULL) goto error;

if(Context_has_access(pycx, jscx, pyobj, attrcheck) <= 0) goto error;

tpl = mk_args_tuple(pycx, jscx, argc, argv);
if(tpl == NULL) goto error;

Expand Down Expand Up @@ -307,6 +320,7 @@ js_call(JSContext* jscx, JSObject* jsobj, uintN argc, jsval* argv, jsval* rval)
success:
Py_XDECREF(tpl);
Py_XDECREF(ret);
Py_XDECREF(attrcheck);
return jsret;
}

Expand All @@ -317,6 +331,7 @@ js_ctor(JSContext* jscx, JSObject* jsobj, uintN argc, jsval* argv, jsval* rval)
PyObject* pyobj = NULL;
PyObject* tpl = NULL;
PyObject* ret = NULL;
PyObject* attrcheck = NULL;
JSBool jsret = JS_FALSE;

pycx = (Context*) JS_GetContextPrivate(jscx);
Expand All @@ -340,6 +355,12 @@ js_ctor(JSContext* jscx, JSObject* jsobj, uintN argc, jsval* argv, jsval* rval)
goto error;
}

// Use '__init__' to signal use as a constructor.
attrcheck = PyString_FromString("__init__");
if(attrcheck == NULL) goto error;

if(Context_has_access(pycx, jscx, pyobj, attrcheck) <= 0) goto error;

tpl = mk_args_tuple(pycx, jscx, argc, argv);
if(tpl == NULL) goto error;

Expand Down
26 changes: 14 additions & 12 deletions spidermonkey/runtime.c
View file
Expand Up @@ -51,20 +51,22 @@ Runtime_new_context(Runtime* self, PyObject* args, PyObject* kwargs)
{
PyObject* cx = NULL;
PyObject* tpl = NULL;
PyObject* global = NULL;
PyObject* global = Py_None;
PyObject* access = Py_None;

if(!PyArg_ParseTuple(args, "|O", &global)) goto error;

if(global == NULL)
{
tpl = Py_BuildValue("(O)", self);
}
else
{
tpl = Py_BuildValue("(OO)", self, global);
}
char* keywords[] = {"glbl", "access", NULL};

if(!PyArg_ParseTupleAndKeywords(
args, kwargs,
"|OO",
keywords,
&global,
&access
)) goto error;

tpl = Py_BuildValue("OOO", self, global, access);
if(tpl == NULL) goto error;

cx = PyObject_CallObject((PyObject*) ContextType, tpl);
goto success;

Expand Down

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