Modules/_ctypes/callbacks.c

#include "Python.h"
#include "frameobject.h"

#include <ffi.h>
#ifdef MS_WIN32
#include <windows.h>
#endif
#include "ctypes.h"

/**************************************************************/

static void
CThunkObject_dealloc(PyObject *_self)
{
    CThunkObject *self = (CThunkObject *)_self;
    PyObject_GC_UnTrack(self);
    Py_XDECREF(self->converters);
    Py_XDECREF(self->callable);
    Py_XDECREF(self->restype);
    if (self->pcl_write)
        ffi_closure_free(self->pcl_write);
    PyObject_GC_Del(self);
}

static int
CThunkObject_traverse(PyObject *_self, visitproc visit, void *arg)
{
    CThunkObject *self = (CThunkObject *)_self;
    Py_VISIT(self->converters);
    Py_VISIT(self->callable);
    Py_VISIT(self->restype);
    return 0;
}

static int
CThunkObject_clear(PyObject *_self)
{
    CThunkObject *self = (CThunkObject *)_self;
    Py_CLEAR(self->converters);
    Py_CLEAR(self->callable);
    Py_CLEAR(self->restype);
    return 0;
}

PyTypeObject PyCThunk_Type = {
    PyVarObject_HEAD_INIT(NULL, 0)
    "_ctypes.CThunkObject",
    sizeof(CThunkObject),                       /* tp_basicsize */
    sizeof(ffi_type),                           /* tp_itemsize */
    CThunkObject_dealloc,                       /* tp_dealloc */
    0,                                          /* tp_print */
    0,                                          /* tp_getattr */
    0,                                          /* tp_setattr */
    0,                                          /* tp_reserved */
    0,                                          /* tp_repr */
    0,                                          /* tp_as_number */
    0,                                          /* tp_as_sequence */
    0,                                          /* tp_as_mapping */
    0,                                          /* tp_hash */
    0,                                          /* tp_call */
    0,                                          /* tp_str */
    0,                                          /* tp_getattro */
    0,                                          /* tp_setattro */
    0,                                          /* tp_as_buffer */
    Py_TPFLAGS_DEFAULT | Py_TPFLAGS_HAVE_GC,                            /* tp_flags */
    "CThunkObject",                             /* tp_doc */
    CThunkObject_traverse,                      /* tp_traverse */
    CThunkObject_clear,                         /* tp_clear */
    0,                                          /* tp_richcompare */
    0,                                          /* tp_weaklistoffset */
    0,                                          /* tp_iter */
    0,                                          /* tp_iternext */
    0,                                          /* tp_methods */
    0,                                          /* tp_members */
};

/**************************************************************/

static void
PrintError(char *msg, ...)
{
    char buf[512];
    PyObject *f = PySys_GetObject("stderr");
    va_list marker;

    va_start(marker, msg);
    vsnprintf(buf, sizeof(buf), msg, marker);
    va_end(marker);
    if (f != NULL && f != Py_None)
        PyFile_WriteString(buf, f);
    PyErr_Print();
}


/* after code that pyrex generates */
void _ctypes_add_traceback(char *funcname, char *filename, int lineno)
{
    PyObject *py_globals = 0;
    PyCodeObject *py_code = 0;
    PyFrameObject *py_frame = 0;
    PyObject *exception, *value, *tb;

    /* (Save and) Clear the current exception. Python functions must not be
       called with an exception set. Calling Python functions happens when
       the codec of the filesystem encoding is implemented in pure Python. */
    PyErr_Fetch(&exception, &value, &tb);

    py_globals = PyDict_New();
    if (!py_globals)
        goto bad;
    py_code = PyCode_NewEmpty(filename, funcname, lineno);
    if (!py_code)
        goto bad;
    py_frame = PyFrame_New(
        PyThreadState_Get(), /*PyThreadState *tstate,*/
        py_code,             /*PyCodeObject *code,*/
        py_globals,          /*PyObject *globals,*/
        0                    /*PyObject *locals*/
        );
    if (!py_frame)
        goto bad;
    py_frame->f_lineno = lineno;

    PyErr_Restore(exception, value, tb);
    PyTraceBack_Here(py_frame);

    Py_DECREF(py_globals);
    Py_DECREF(py_code);
    Py_DECREF(py_frame);
    return;

  bad:
    Py_XDECREF(py_globals);
    Py_XDECREF(py_code);
    Py_XDECREF(py_frame);
}

#ifdef MS_WIN32
/*
 * We must call AddRef() on non-NULL COM pointers we receive as arguments
 * to callback functions - these functions are COM method implementations.
 * The Python instances we create have a __del__ method which calls Release().
 *
 * The presence of a class attribute named '_needs_com_addref_' triggers this
 * behaviour.  It would also be possible to call the AddRef() Python method,
 * after checking for PyObject_IsTrue(), but this would probably be somewhat
 * slower.
 */
static void
TryAddRef(StgDictObject *dict, CDataObject *obj)
{
    IUnknown *punk;

    if (NULL == PyDict_GetItemString((PyObject *)dict, "_needs_com_addref_"))
        return;

    punk = *(IUnknown **)obj->b_ptr;
    if (punk)
        punk->lpVtbl->AddRef(punk);
    return;
}
#endif

/******************************************************************************
 *
 * Call the python object with all arguments
 *
 */
static void _CallPythonObject(void *mem,
                              ffi_type *restype,
                              SETFUNC setfunc,
                              PyObject *callable,
                              PyObject *converters,
                              int flags,
                              void **pArgs)
{
    Py_ssize_t i;
    PyObject *result;
    PyObject *arglist = NULL;
    Py_ssize_t nArgs;
    PyObject *error_object = NULL;
    int *space;
#ifdef WITH_THREAD
    PyGILState_STATE state = PyGILState_Ensure();
#endif

    nArgs = PySequence_Length(converters);
    /* Hm. What to return in case of error?
       For COM, 0xFFFFFFFF seems better than 0.
    */
    if (nArgs < 0) {
        PrintError("BUG: PySequence_Length");
        goto Done;
    }

    arglist = PyTuple_New(nArgs);
    if (!arglist) {
        PrintError("PyTuple_New()");
        goto Done;
    }
    for (i = 0; i < nArgs; ++i) {
        /* Note: new reference! */
        PyObject *cnv = PySequence_GetItem(converters, i);
        StgDictObject *dict;
        if (cnv)
            dict = PyType_stgdict(cnv);
        else {
            PrintError("Getting argument converter %d\n", i);
            goto Done;
        }

        if (dict && dict->getfunc && !_ctypes_simple_instance(cnv)) {
            PyObject *v = dict->getfunc(*pArgs, dict->size);
            if (!v) {
                PrintError("create argument %d:\n", i);
                Py_DECREF(cnv);
                goto Done;
            }
            PyTuple_SET_ITEM(arglist, i, v);
            /* XXX XXX XX
               We have the problem that c_byte or c_short have dict->size of
               1 resp. 4, but these parameters are pushed as sizeof(int) bytes.
               BTW, the same problem occurs when they are pushed as parameters
            */
        } else if (dict) {
            /* Hm, shouldn't we use PyCData_AtAddress() or something like that instead? */
            CDataObject *obj = (CDataObject *)PyObject_CallFunctionObjArgs(cnv, NULL);
            if (!obj) {
                PrintError("create argument %d:\n", i);
                Py_DECREF(cnv);
                goto Done;
            }
            if (!CDataObject_Check(obj)) {
                Py_DECREF(obj);
                Py_DECREF(cnv);
                PrintError("unexpected result of create argument %d:\n", i);
                goto Done;
            }
            memcpy(obj->b_ptr, *pArgs, dict->size);
            PyTuple_SET_ITEM(arglist, i, (PyObject *)obj);
#ifdef MS_WIN32
            TryAddRef(dict, obj);
#endif
        } else {
            PyErr_SetString(PyExc_TypeError,
                            "cannot build parameter");
            PrintError("Parsing argument %d\n", i);
            Py_DECREF(cnv);
            goto Done;
        }
        Py_DECREF(cnv);
        /* XXX error handling! */
        pArgs++;
    }

#define CHECK(what, x) \
if (x == NULL) _ctypes_add_traceback(what, "_ctypes/callbacks.c", __LINE__ - 1), PyErr_Print()

    if (flags & (FUNCFLAG_USE_ERRNO | FUNCFLAG_USE_LASTERROR)) {
        error_object = _ctypes_get_errobj(&space);
        if (error_object == NULL)
            goto Done;
        if (flags & FUNCFLAG_USE_ERRNO) {
            int temp = space[0];
            space[0] = errno;
            errno = temp;
        }
#ifdef MS_WIN32
        if (flags & FUNCFLAG_USE_LASTERROR) {
            int temp = space[1];
            space[1] = GetLastError();
            SetLastError(temp);
        }
#endif
    }

    result = PyObject_CallObject(callable, arglist);
    CHECK("'calling callback function'", result);

#ifdef MS_WIN32
    if (flags & FUNCFLAG_USE_LASTERROR) {
        int temp = space[1];
        space[1] = GetLastError();
        SetLastError(temp);
    }
#endif
    if (flags & FUNCFLAG_USE_ERRNO) {
        int temp = space[0];
        space[0] = errno;
        errno = temp;
    }
    Py_XDECREF(error_object);

    if ((restype != &ffi_type_void) && result) {
        PyObject *keep;
        assert(setfunc);
#ifdef WORDS_BIGENDIAN
        /* See the corresponding code in callproc.c, around line 961 */
        if (restype->type != FFI_TYPE_FLOAT && restype->size < sizeof(ffi_arg))
            mem = (char *)mem + sizeof(ffi_arg) - restype->size;
#endif
        keep = setfunc(mem, result, 0);
        CHECK("'converting callback result'", keep);
        /* keep is an object we have to keep alive so that the result
           stays valid.  If there is no such object, the setfunc will
           have returned Py_None.

           If there is such an object, we have no choice than to keep
           it alive forever - but a refcount and/or memory leak will
           be the result.  EXCEPT when restype is py_object - Python
           itself knows how to manage the refcount of these objects.
        */
        if (keep == NULL) /* Could not convert callback result. */
            PyErr_WriteUnraisable(callable);
        else if (keep == Py_None) /* Nothing to keep */
            Py_DECREF(keep);
        else if (setfunc != _ctypes_get_fielddesc("O")->setfunc) {
            if (-1 == PyErr_WarnEx(PyExc_RuntimeWarning,
                                   "memory leak in callback function.",
                                   1))
                PyErr_WriteUnraisable(callable);
        }
    }
    Py_XDECREF(result);
  Done:
    Py_XDECREF(arglist);
#ifdef WITH_THREAD
    PyGILState_Release(state);
#endif
}

static void closure_fcn(ffi_cif *cif,
                        void *resp,
                        void **args,
                        void *userdata)
{
    CThunkObject *p = (CThunkObject *)userdata;

    _CallPythonObject(resp,
                      p->ffi_restype,
                      p->setfunc,
                      p->callable,
                      p->converters,
                      p->flags,
                      args);
}

static CThunkObject* CThunkObject_new(Py_ssize_t nArgs)
{
    CThunkObject *p;
    int i;

    p = PyObject_GC_NewVar(CThunkObject, &PyCThunk_Type, nArgs);
    if (p == NULL) {
        PyErr_NoMemory();
        return NULL;
    }

    p->pcl_exec = NULL;
    p->pcl_write = NULL;
    memset(&p->cif, 0, sizeof(p->cif));
    p->converters = NULL;
    p->callable = NULL;
    p->setfunc = NULL;
    p->ffi_restype = NULL;

    for (i = 0; i < nArgs + 1; ++i)
        p->atypes[i] = NULL;
    PyObject_GC_Track((PyObject *)p);
    return p;
}

CThunkObject *_ctypes_alloc_callback(PyObject *callable,
                                    PyObject *converters,
                                    PyObject *restype,
                                    int flags)
{
    int result;
    CThunkObject *p;
    Py_ssize_t nArgs, i;
    ffi_abi cc;

    nArgs = PySequence_Size(converters);
    p = CThunkObject_new(nArgs);
    if (p == NULL)
        return NULL;

    assert(CThunk_CheckExact((PyObject *)p));

    p->pcl_write = ffi_closure_alloc(sizeof(ffi_closure),
									 &p->pcl_exec);
    if (p->pcl_write == NULL) {
        PyErr_NoMemory();
        goto error;
    }

    p->flags = flags;
    for (i = 0; i < nArgs; ++i) {
        PyObject *cnv = PySequence_GetItem(converters, i);
        if (cnv == NULL)
            goto error;
        p->atypes[i] = _ctypes_get_ffi_type(cnv);
        Py_DECREF(cnv);
    }
    p->atypes[i] = NULL;

    Py_INCREF(restype);
    p->restype = restype;
    if (restype == Py_None) {
        p->setfunc = NULL;
        p->ffi_restype = &ffi_type_void;
    } else {
        StgDictObject *dict = PyType_stgdict(restype);
        if (dict == NULL || dict->setfunc == NULL) {
          PyErr_SetString(PyExc_TypeError,
                          "invalid result type for callback function");
          goto error;
        }
        p->setfunc = dict->setfunc;
        p->ffi_restype = &dict->ffi_type_pointer;
    }

    cc = FFI_DEFAULT_ABI;
#if defined(MS_WIN32) && !defined(_WIN32_WCE) && !defined(MS_WIN64)
    if ((flags & FUNCFLAG_CDECL) == 0)
        cc = FFI_STDCALL;
#endif
    result = ffi_prep_cif(&p->cif, cc,
                          Py_SAFE_DOWNCAST(nArgs, Py_ssize_t, int),
                          _ctypes_get_ffi_type(restype),
                          &p->atypes[0]);
    if (result != FFI_OK) {
        PyErr_Format(PyExc_RuntimeError,
                     "ffi_prep_cif failed with %d", result);
        goto error;
    }
#if defined(X86_DARWIN) || defined(POWERPC_DARWIN)
    result = ffi_prep_closure(p->pcl_write, &p->cif, closure_fcn, p);
#else
    result = ffi_prep_closure_loc(p->pcl_write, &p->cif, closure_fcn,
				  p,
				  p->pcl_exec);
#endif
    if (result != FFI_OK) {
        PyErr_Format(PyExc_RuntimeError,
                     "ffi_prep_closure failed with %d", result);
        goto error;
    }

    Py_INCREF(converters);
    p->converters = converters;
    Py_INCREF(callable);
    p->callable = callable;
    return p;

  error:
    Py_XDECREF(p);
    return NULL;
}

#ifdef MS_WIN32

static void LoadPython(void)
{
    if (!Py_IsInitialized()) {
#ifdef WITH_THREAD
        PyEval_InitThreads();
#endif
        Py_Initialize();
    }
}

/******************************************************************/

long Call_GetClassObject(REFCLSID rclsid, REFIID riid, LPVOID *ppv)
{
    PyObject *mod, *func, *result;
    long retval;
    static PyObject *context;

    if (context == NULL)
        context = PyUnicode_InternFromString("_ctypes.DllGetClassObject");

    mod = PyImport_ImportModuleNoBlock("ctypes");
    if (!mod) {
        PyErr_WriteUnraisable(context ? context : Py_None);
        /* There has been a warning before about this already */
        return E_FAIL;
    }

    func = PyObject_GetAttrString(mod, "DllGetClassObject");
    Py_DECREF(mod);
    if (!func) {
        PyErr_WriteUnraisable(context ? context : Py_None);
        return E_FAIL;
    }

    {
        PyObject *py_rclsid = PyLong_FromVoidPtr((void *)rclsid);
        PyObject *py_riid = PyLong_FromVoidPtr((void *)riid);
        PyObject *py_ppv = PyLong_FromVoidPtr(ppv);
        if (!py_rclsid || !py_riid || !py_ppv) {
            Py_XDECREF(py_rclsid);
            Py_XDECREF(py_riid);
            Py_XDECREF(py_ppv);
            Py_DECREF(func);
            PyErr_WriteUnraisable(context ? context : Py_None);
            return E_FAIL;
        }
        result = PyObject_CallFunctionObjArgs(func,
                                              py_rclsid,
                                              py_riid,
                                              py_ppv,
                                              NULL);
        Py_DECREF(py_rclsid);
        Py_DECREF(py_riid);
        Py_DECREF(py_ppv);
    }
    Py_DECREF(func);
    if (!result) {
        PyErr_WriteUnraisable(context ? context : Py_None);
        return E_FAIL;
    }

    retval = PyLong_AsLong(result);
    if (PyErr_Occurred()) {
        PyErr_WriteUnraisable(context ? context : Py_None);
        retval = E_FAIL;
    }
    Py_DECREF(result);
    return retval;
}

STDAPI DllGetClassObject(REFCLSID rclsid,
                         REFIID riid,
                         LPVOID *ppv)
{
    long result;
#ifdef WITH_THREAD
    PyGILState_STATE state;
#endif

    LoadPython();
#ifdef WITH_THREAD
    state = PyGILState_Ensure();
#endif
    result = Call_GetClassObject(rclsid, riid, ppv);
#ifdef WITH_THREAD
    PyGILState_Release(state);
#endif
    return result;
}

long Call_CanUnloadNow(void)
{
    PyObject *mod, *func, *result;
    long retval;
    static PyObject *context;

    if (context == NULL)
        context = PyUnicode_InternFromString("_ctypes.DllCanUnloadNow");

    mod = PyImport_ImportModuleNoBlock("ctypes");
    if (!mod) {
/*              OutputDebugString("Could not import ctypes"); */
        /* We assume that this error can only occur when shutting
           down, so we silently ignore it */
        PyErr_Clear();
        return E_FAIL;
    }
    /* Other errors cannot be raised, but are printed to stderr */
    func = PyObject_GetAttrString(mod, "DllCanUnloadNow");
    Py_DECREF(mod);
    if (!func) {
        PyErr_WriteUnraisable(context ? context : Py_None);
        return E_FAIL;
    }

    result = PyObject_CallFunction(func, NULL);
    Py_DECREF(func);
    if (!result) {
        PyErr_WriteUnraisable(context ? context : Py_None);
        return E_FAIL;
    }

    retval = PyLong_AsLong(result);
    if (PyErr_Occurred()) {
        PyErr_WriteUnraisable(context ? context : Py_None);
        retval = E_FAIL;
    }
    Py_DECREF(result);
    return retval;
}

/*
  DllRegisterServer and DllUnregisterServer still missing
*/

STDAPI DllCanUnloadNow(void)
{
    long result;
#ifdef WITH_THREAD
    PyGILState_STATE state = PyGILState_Ensure();
#endif
    result = Call_CanUnloadNow();
#ifdef WITH_THREAD
    PyGILState_Release(state);
#endif
    return result;
}

#ifndef Py_NO_ENABLE_SHARED
BOOL WINAPI DllMain(HINSTANCE hinstDLL, DWORD fdwReason, LPVOID lpvRes)
{
    switch(fdwReason) {
    case DLL_PROCESS_ATTACH:
        DisableThreadLibraryCalls(hinstDLL);
        break;
    }
    return TRUE;
}
#endif

#endif

/*
 Local Variables:
 compile-command: "cd .. && python setup.py -q build_ext"
 End:
*/