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cpython/Python/crossinterp.c

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/* API for managing interactions between isolated interpreters */
#include "Python.h"
#include "pycore_ceval.h" // _Py_simple_func
#include "pycore_crossinterp.h" // struct _xid
#include "pycore_initconfig.h" // _PyStatus_OK()
#include "pycore_namespace.h" //_PyNamespace_New()
#include "pycore_pyerrors.h" // _PyErr_Clear()
#include "pycore_weakref.h" // _PyWeakref_GET_REF()
/**************/
/* exceptions */
/**************/
static int init_exceptions(PyInterpreterState *);
static void fini_exceptions(PyInterpreterState *);
static int _init_not_shareable_error_type(PyInterpreterState *);
static void _fini_not_shareable_error_type(PyInterpreterState *);
static PyObject * _get_not_shareable_error_type(PyInterpreterState *);
#include "crossinterp_exceptions.h"
/***************************/
/* cross-interpreter calls */
/***************************/
int
_Py_CallInInterpreter(PyInterpreterState *interp,
_Py_simple_func func, void *arg)
{
if (interp == PyInterpreterState_Get()) {
return func(arg);
}
// XXX Emit a warning if this fails?
_PyEval_AddPendingCall(interp, (_Py_pending_call_func)func, arg, 0);
return 0;
}
int
_Py_CallInInterpreterAndRawFree(PyInterpreterState *interp,
_Py_simple_func func, void *arg)
{
if (interp == PyInterpreterState_Get()) {
int res = func(arg);
PyMem_RawFree(arg);
return res;
}
// XXX Emit a warning if this fails?
_PyEval_AddPendingCall(interp, func, arg, _Py_PENDING_RAWFREE);
return 0;
}
/**************************/
/* cross-interpreter data */
/**************************/
/* registry of {type -> crossinterpdatafunc} */
/* For now we use a global registry of shareable classes. An
alternative would be to add a tp_* slot for a class's
crossinterpdatafunc. It would be simpler and more efficient. */
static void xid_lookup_init(PyInterpreterState *);
static void xid_lookup_fini(PyInterpreterState *);
static crossinterpdatafunc lookup_getdata(PyInterpreterState *, PyObject *);
#include "crossinterp_data_lookup.h"
/* lifecycle */
_PyCrossInterpreterData *
_PyCrossInterpreterData_New(void)
{
_PyCrossInterpreterData *xid = PyMem_RawMalloc(
sizeof(_PyCrossInterpreterData));
if (xid == NULL) {
PyErr_NoMemory();
}
return xid;
}
void
_PyCrossInterpreterData_Free(_PyCrossInterpreterData *xid)
{
PyInterpreterState *interp = PyInterpreterState_Get();
_PyCrossInterpreterData_Clear(interp, xid);
PyMem_RawFree(xid);
}
/* defining cross-interpreter data */
static inline void
_xidata_init(_PyCrossInterpreterData *data)
{
// If the value is being reused
// then _xidata_clear() should have been called already.
assert(data->data == NULL);
assert(data->obj == NULL);
*data = (_PyCrossInterpreterData){0};
_PyCrossInterpreterData_INTERPID(data) = -1;
}
static inline void
_xidata_clear(_PyCrossInterpreterData *data)
{
// _PyCrossInterpreterData only has two members that need to be
// cleaned up, if set: "data" must be freed and "obj" must be decref'ed.
// In both cases the original (owning) interpreter must be used,
// which is the caller's responsibility to ensure.
if (data->data != NULL) {
if (data->free != NULL) {
data->free(data->data);
}
data->data = NULL;
}
Py_CLEAR(data->obj);
}
void
_PyCrossInterpreterData_Init(_PyCrossInterpreterData *data,
PyInterpreterState *interp,
void *shared, PyObject *obj,
xid_newobjectfunc new_object)
{
assert(data != NULL);
assert(new_object != NULL);
_xidata_init(data);
data->data = shared;
if (obj != NULL) {
assert(interp != NULL);
// released in _PyCrossInterpreterData_Clear()
data->obj = Py_NewRef(obj);
}
// Ideally every object would know its owning interpreter.
// Until then, we have to rely on the caller to identify it
// (but we don't need it in all cases).
_PyCrossInterpreterData_INTERPID(data) = (interp != NULL)
? PyInterpreterState_GetID(interp)
: -1;
data->new_object = new_object;
}
int
_PyCrossInterpreterData_InitWithSize(_PyCrossInterpreterData *data,
PyInterpreterState *interp,
const size_t size, PyObject *obj,
xid_newobjectfunc new_object)
{
assert(size > 0);
// For now we always free the shared data in the same interpreter
// where it was allocated, so the interpreter is required.
assert(interp != NULL);
_PyCrossInterpreterData_Init(data, interp, NULL, obj, new_object);
data->data = PyMem_RawMalloc(size);
if (data->data == NULL) {
return -1;
}
data->free = PyMem_RawFree;
return 0;
}
void
_PyCrossInterpreterData_Clear(PyInterpreterState *interp,
_PyCrossInterpreterData *data)
{
assert(data != NULL);
// This must be called in the owning interpreter.
assert(interp == NULL
|| _PyCrossInterpreterData_INTERPID(data) == -1
|| _PyCrossInterpreterData_INTERPID(data) == PyInterpreterState_GetID(interp));
_xidata_clear(data);
}
/* using cross-interpreter data */
static int
_check_xidata(PyThreadState *tstate, _PyCrossInterpreterData *data)
{
// data->data can be anything, including NULL, so we don't check it.
// data->obj may be NULL, so we don't check it.
if (_PyCrossInterpreterData_INTERPID(data) < 0) {
PyErr_SetString(PyExc_SystemError, "missing interp");
return -1;
}
if (data->new_object == NULL) {
PyErr_SetString(PyExc_SystemError, "missing new_object func");
return -1;
}
// data->free may be NULL, so we don't check it.
return 0;
}
static inline void
_set_xid_lookup_failure(PyInterpreterState *interp,
PyObject *obj, const char *msg)
{
PyObject *exctype = _get_not_shareable_error_type(interp);
assert(exctype != NULL);
if (msg != NULL) {
assert(obj == NULL);
PyErr_SetString(exctype, msg);
}
else if (obj == NULL) {
PyErr_SetString(exctype,
"object does not support cross-interpreter data");
}
else {
PyErr_Format(exctype,
"%S does not support cross-interpreter data", obj);
}
}
int
_PyObject_CheckCrossInterpreterData(PyObject *obj)
{
PyInterpreterState *interp = PyInterpreterState_Get();
crossinterpdatafunc getdata = lookup_getdata(interp, obj);
if (getdata == NULL) {
if (!PyErr_Occurred()) {
_set_xid_lookup_failure(interp, obj, NULL);
}
return -1;
}
return 0;
}
int
_PyObject_GetCrossInterpreterData(PyObject *obj, _PyCrossInterpreterData *data)
{
PyThreadState *tstate = PyThreadState_Get();
PyInterpreterState *interp = tstate->interp;
// Reset data before re-populating.
*data = (_PyCrossInterpreterData){0};
_PyCrossInterpreterData_INTERPID(data) = -1;
// Call the "getdata" func for the object.
Py_INCREF(obj);
crossinterpdatafunc getdata = lookup_getdata(interp, obj);
if (getdata == NULL) {
Py_DECREF(obj);
if (!PyErr_Occurred()) {
_set_xid_lookup_failure(interp, obj, NULL);
}
return -1;
}
int res = getdata(tstate, obj, data);
Py_DECREF(obj);
if (res != 0) {
return -1;
}
// Fill in the blanks and validate the result.
_PyCrossInterpreterData_INTERPID(data) = PyInterpreterState_GetID(interp);
if (_check_xidata(tstate, data) != 0) {
(void)_PyCrossInterpreterData_Release(data);
return -1;
}
return 0;
}
PyObject *
_PyCrossInterpreterData_NewObject(_PyCrossInterpreterData *data)
{
return data->new_object(data);
}
static int
_call_clear_xidata(void *data)
{
_xidata_clear((_PyCrossInterpreterData *)data);
return 0;
}
static int
_xidata_release(_PyCrossInterpreterData *data, int rawfree)
{
if ((data->data == NULL || data->free == NULL) && data->obj == NULL) {
// Nothing to release!
if (rawfree) {
PyMem_RawFree(data);
}
else {
data->data = NULL;
}
return 0;
}
// Switch to the original interpreter.
PyInterpreterState *interp = _PyInterpreterState_LookUpID(
_PyCrossInterpreterData_INTERPID(data));
if (interp == NULL) {
// The interpreter was already destroyed.
// This function shouldn't have been called.
// XXX Someone leaked some memory...
assert(PyErr_Occurred());
if (rawfree) {
PyMem_RawFree(data);
}
return -1;
}
// "Release" the data and/or the object.
if (rawfree) {
return _Py_CallInInterpreterAndRawFree(interp, _call_clear_xidata, data);
}
else {
return _Py_CallInInterpreter(interp, _call_clear_xidata, data);
}
}
int
_PyCrossInterpreterData_Release(_PyCrossInterpreterData *data)
{
return _xidata_release(data, 0);
}
int
_PyCrossInterpreterData_ReleaseAndRawFree(_PyCrossInterpreterData *data)
{
return _xidata_release(data, 1);
}
/*************************/
/* convenience utilities */
/*************************/
static const char *
_copy_string_obj_raw(PyObject *strobj, Py_ssize_t *p_size)
{
Py_ssize_t size = -1;
const char *str = PyUnicode_AsUTF8AndSize(strobj, &size);
if (str == NULL) {
return NULL;
}
char *copied = PyMem_RawMalloc(size+1);
if (copied == NULL) {
PyErr_NoMemory();
return NULL;
}
strcpy(copied, str);
if (p_size != NULL) {
*p_size = size;
}
return copied;
}
static int
_convert_exc_to_TracebackException(PyObject *exc, PyObject **p_tbexc)
{
PyObject *args = NULL;
PyObject *kwargs = NULL;
PyObject *create = NULL;
// This is inspired by _PyErr_Display().
PyObject *tbmod = PyImport_ImportModule("traceback");
if (tbmod == NULL) {
return -1;
}
PyObject *tbexc_type = PyObject_GetAttrString(tbmod, "TracebackException");
Py_DECREF(tbmod);
if (tbexc_type == NULL) {
return -1;
}
create = PyObject_GetAttrString(tbexc_type, "from_exception");
Py_DECREF(tbexc_type);
if (create == NULL) {
return -1;
}
args = PyTuple_Pack(1, exc);
if (args == NULL) {
goto error;
}
kwargs = PyDict_New();
if (kwargs == NULL) {
goto error;
}
if (PyDict_SetItemString(kwargs, "save_exc_type", Py_False) < 0) {
goto error;
}
if (PyDict_SetItemString(kwargs, "lookup_lines", Py_False) < 0) {
goto error;
}
PyObject *tbexc = PyObject_Call(create, args, kwargs);
Py_DECREF(args);
Py_DECREF(kwargs);
Py_DECREF(create);
if (tbexc == NULL) {
goto error;
}
*p_tbexc = tbexc;
return 0;
error:
Py_XDECREF(args);
Py_XDECREF(kwargs);
Py_XDECREF(create);
return -1;
}
// We accommodate backports here.
#ifndef _Py_EMPTY_STR
# define _Py_EMPTY_STR &_Py_STR(empty)
#endif
static const char *
_format_TracebackException(PyObject *tbexc)
{
PyObject *lines = PyObject_CallMethod(tbexc, "format", NULL);
if (lines == NULL) {
return NULL;
}
assert(_Py_EMPTY_STR != NULL);
PyObject *formatted_obj = PyUnicode_Join(_Py_EMPTY_STR, lines);
Py_DECREF(lines);
if (formatted_obj == NULL) {
return NULL;
}
Py_ssize_t size = -1;
const char *formatted = _copy_string_obj_raw(formatted_obj, &size);
Py_DECREF(formatted_obj);
// We remove trailing the newline added by TracebackException.format().
assert(formatted[size-1] == '\n');
((char *)formatted)[size-1] = '\0';
return formatted;
}
static int
_release_xid_data(_PyCrossInterpreterData *data, int rawfree)
{
PyObject *exc = PyErr_GetRaisedException();
int res = rawfree
? _PyCrossInterpreterData_Release(data)
: _PyCrossInterpreterData_ReleaseAndRawFree(data);
if (res < 0) {
/* The owning interpreter is already destroyed. */
_PyCrossInterpreterData_Clear(NULL, data);
// XXX Emit a warning?
PyErr_Clear();
}
PyErr_SetRaisedException(exc);
return res;
}
/***********************/
/* exception snapshots */
/***********************/
static int
_excinfo_init_type(struct _excinfo_type *info, PyObject *exc)
{
/* Note that this copies directly rather than into an intermediate
struct and does not clear on error. If we need that then we
should have a separate function to wrap this one
and do all that there. */
PyObject *strobj = NULL;
PyTypeObject *type = Py_TYPE(exc);
if (type->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN) {
assert(_Py_IsImmortal((PyObject *)type));
info->builtin = type;
}
else {
// Only builtin types are preserved.
info->builtin = NULL;
}
// __name__
strobj = PyType_GetName(type);
if (strobj == NULL) {
return -1;
}
info->name = _copy_string_obj_raw(strobj, NULL);
Py_DECREF(strobj);
if (info->name == NULL) {
return -1;
}
// __qualname__
strobj = PyType_GetQualName(type);
if (strobj == NULL) {
return -1;
}
info->qualname = _copy_string_obj_raw(strobj, NULL);
Py_DECREF(strobj);
if (info->name == NULL) {
return -1;
}
// __module__
strobj = PyType_GetModuleName(type);
if (strobj == NULL) {
return -1;
}
info->module = _copy_string_obj_raw(strobj, NULL);
Py_DECREF(strobj);
if (info->name == NULL) {
return -1;
}
return 0;
}
static void
_excinfo_clear_type(struct _excinfo_type *info)
{
if (info->builtin != NULL) {
assert(info->builtin->tp_flags & _Py_TPFLAGS_STATIC_BUILTIN);
assert(_Py_IsImmortal((PyObject *)info->builtin));
}
if (info->name != NULL) {
PyMem_RawFree((void *)info->name);
}
if (info->qualname != NULL) {
PyMem_RawFree((void *)info->qualname);
}
if (info->module != NULL) {
PyMem_RawFree((void *)info->module);
}
*info = (struct _excinfo_type){NULL};
}
static void
_excinfo_normalize_type(struct _excinfo_type *info,
const char **p_module, const char **p_qualname)
{
if (info->name == NULL) {
assert(info->builtin == NULL);
assert(info->qualname == NULL);
assert(info->module == NULL);
// This is inspired by TracebackException.format_exception_only().
*p_module = NULL;
*p_qualname = NULL;
return;
}
const char *module = info->module;
const char *qualname = info->qualname;
if (qualname == NULL) {
qualname = info->name;
}
assert(module != NULL);
if (strcmp(module, "builtins") == 0) {
module = NULL;
}
else if (strcmp(module, "__main__") == 0) {
module = NULL;
}
*p_qualname = qualname;
*p_module = module;
}
static void
_PyXI_excinfo_Clear(_PyXI_excinfo *info)
{
_excinfo_clear_type(&info->type);
if (info->msg != NULL) {
PyMem_RawFree((void *)info->msg);
}
if (info->errdisplay != NULL) {
PyMem_RawFree((void *)info->errdisplay);
}
*info = (_PyXI_excinfo){{NULL}};
}
static PyObject *
_PyXI_excinfo_format(_PyXI_excinfo *info)
{
const char *module, *qualname;
_excinfo_normalize_type(&info->type, &module, &qualname);
if (qualname != NULL) {
if (module != NULL) {
if (info->msg != NULL) {
return PyUnicode_FromFormat("%s.%s: %s",
module, qualname, info->msg);
}
else {
return PyUnicode_FromFormat("%s.%s", module, qualname);
}
}
else {
if (info->msg != NULL) {
return PyUnicode_FromFormat("%s: %s", qualname, info->msg);
}
else {
return PyUnicode_FromString(qualname);
}
}
}
else if (info->msg != NULL) {
return PyUnicode_FromString(info->msg);
}
else {
Py_RETURN_NONE;
}
}
static const char *
_PyXI_excinfo_InitFromException(_PyXI_excinfo *info, PyObject *exc)
{
assert(exc != NULL);
if (PyErr_GivenExceptionMatches(exc, PyExc_MemoryError)) {
_PyXI_excinfo_Clear(info);
return NULL;
}
const char *failure = NULL;
if (_excinfo_init_type(&info->type, exc) < 0) {
failure = "error while initializing exception type snapshot";
goto error;
}
// Extract the exception message.
PyObject *msgobj = PyObject_Str(exc);
if (msgobj == NULL) {
failure = "error while formatting exception";
goto error;
}
info->msg = _copy_string_obj_raw(msgobj, NULL);
Py_DECREF(msgobj);
if (info->msg == NULL) {
failure = "error while copying exception message";
goto error;
}
// Pickle a traceback.TracebackException.
PyObject *tbexc = NULL;
if (_convert_exc_to_TracebackException(exc, &tbexc) < 0) {
#ifdef Py_DEBUG
PyErr_FormatUnraisable("Exception ignored while creating TracebackException");
#endif
PyErr_Clear();
}
else {
info->errdisplay = _format_TracebackException(tbexc);
Py_DECREF(tbexc);
if (info->errdisplay == NULL) {
#ifdef Py_DEBUG
PyErr_FormatUnraisable("Exception ignored while formating TracebackException");
#endif
PyErr_Clear();
}
}
return NULL;
error:
assert(failure != NULL);
_PyXI_excinfo_Clear(info);
return failure;
}
static void
_PyXI_excinfo_Apply(_PyXI_excinfo *info, PyObject *exctype)
{
PyObject *tbexc = NULL;
if (info->errdisplay != NULL) {
tbexc = PyUnicode_FromString(info->errdisplay);
if (tbexc == NULL) {
PyErr_Clear();
}
}
PyObject *formatted = _PyXI_excinfo_format(info);
PyErr_SetObject(exctype, formatted);
Py_DECREF(formatted);
if (tbexc != NULL) {
PyObject *exc = PyErr_GetRaisedException();
if (PyObject_SetAttrString(exc, "_errdisplay", tbexc) < 0) {
#ifdef Py_DEBUG
PyErr_FormatUnraisable("Exception ignored when setting _errdisplay");
#endif
PyErr_Clear();
}
Py_DECREF(tbexc);
PyErr_SetRaisedException(exc);
}
}
static PyObject *
_PyXI_excinfo_TypeAsObject(_PyXI_excinfo *info)
{
PyObject *ns = _PyNamespace_New(NULL);
if (ns == NULL) {
return NULL;
}
int empty = 1;
if (info->type.name != NULL) {
PyObject *name = PyUnicode_FromString(info->type.name);
if (name == NULL) {
goto error;
}
int res = PyObject_SetAttrString(ns, "__name__", name);
Py_DECREF(name);
if (res < 0) {
goto error;
}
empty = 0;
}
if (info->type.qualname != NULL) {
PyObject *qualname = PyUnicode_FromString(info->type.qualname);
if (qualname == NULL) {
goto error;
}
int res = PyObject_SetAttrString(ns, "__qualname__", qualname);
Py_DECREF(qualname);
if (res < 0) {
goto error;
}
empty = 0;
}
if (info->type.module != NULL) {
PyObject *module = PyUnicode_FromString(info->type.module);
if (module == NULL) {
goto error;
}
int res = PyObject_SetAttrString(ns, "__module__", module);
Py_DECREF(module);
if (res < 0) {
goto error;
}
empty = 0;
}
if (empty) {
Py_CLEAR(ns);
}
return ns;
error:
Py_DECREF(ns);
return NULL;
}
static PyObject *
_PyXI_excinfo_AsObject(_PyXI_excinfo *info)
{
PyObject *ns = _PyNamespace_New(NULL);
if (ns == NULL) {
return NULL;
}
int res;
PyObject *type = _PyXI_excinfo_TypeAsObject(info);
if (type == NULL) {
if (PyErr_Occurred()) {
goto error;
}
type = Py_NewRef(Py_None);
}
res = PyObject_SetAttrString(ns, "type", type);
Py_DECREF(type);
if (res < 0) {
goto error;
}
PyObject *msg = info->msg != NULL
? PyUnicode_FromString(info->msg)
: Py_NewRef(Py_None);
if (msg == NULL) {
goto error;
}
res = PyObject_SetAttrString(ns, "msg", msg);
Py_DECREF(msg);
if (res < 0) {
goto error;
}
PyObject *formatted = _PyXI_excinfo_format(info);
if (formatted == NULL) {
goto error;
}
res = PyObject_SetAttrString(ns, "formatted", formatted);
Py_DECREF(formatted);
if (res < 0) {
goto error;
}
if (info->errdisplay != NULL) {
PyObject *tbexc = PyUnicode_FromString(info->errdisplay);
if (tbexc == NULL) {
PyErr_Clear();
}
else {
res = PyObject_SetAttrString(ns, "errdisplay", tbexc);
Py_DECREF(tbexc);
if (res < 0) {
goto error;
}
}
}
return ns;
error:
Py_DECREF(ns);
return NULL;
}
/***************************/
/* short-term data sharing */
/***************************/
/* error codes */
static int
_PyXI_ApplyErrorCode(_PyXI_errcode code, PyInterpreterState *interp)
{
assert(!PyErr_Occurred());
switch (code) {
case _PyXI_ERR_NO_ERROR: // fall through
case _PyXI_ERR_UNCAUGHT_EXCEPTION:
// There is nothing to apply.
#ifdef Py_DEBUG
Py_UNREACHABLE();
#endif
return 0;
case _PyXI_ERR_OTHER:
// XXX msg?
PyErr_SetNone(PyExc_InterpreterError);
break;
case _PyXI_ERR_NO_MEMORY:
PyErr_NoMemory();
break;
case _PyXI_ERR_ALREADY_RUNNING:
assert(interp != NULL);
assert(_PyInterpreterState_IsRunningMain(interp));
_PyInterpreterState_FailIfRunningMain(interp);
break;
case _PyXI_ERR_MAIN_NS_FAILURE:
PyErr_SetString(PyExc_InterpreterError,
"failed to get __main__ namespace");
break;
case _PyXI_ERR_APPLY_NS_FAILURE:
PyErr_SetString(PyExc_InterpreterError,
"failed to apply namespace to __main__");
break;
case _PyXI_ERR_NOT_SHAREABLE:
_set_xid_lookup_failure(interp, NULL, NULL);
break;
default:
#ifdef Py_DEBUG
Py_UNREACHABLE();
#else
PyErr_Format(PyExc_RuntimeError, "unsupported error code %d", code);
#endif
}
assert(PyErr_Occurred());
return -1;
}
/* shared exceptions */
static const char *
_PyXI_InitError(_PyXI_error *error, PyObject *excobj, _PyXI_errcode code)
{
if (error->interp == NULL) {
error->interp = PyInterpreterState_Get();
}
const char *failure = NULL;
if (code == _PyXI_ERR_UNCAUGHT_EXCEPTION) {
// There is an unhandled exception we need to propagate.
failure = _PyXI_excinfo_InitFromException(&error->uncaught, excobj);
if (failure != NULL) {
// We failed to initialize error->uncaught.
// XXX Print the excobj/traceback? Emit a warning?
// XXX Print the current exception/traceback?
if (PyErr_ExceptionMatches(PyExc_MemoryError)) {
error->code = _PyXI_ERR_NO_MEMORY;
}
else {
error->code = _PyXI_ERR_OTHER;
}
PyErr_Clear();
}
else {
error->code = code;
}
assert(error->code != _PyXI_ERR_NO_ERROR);
}
else {
// There is an error code we need to propagate.
assert(excobj == NULL);
assert(code != _PyXI_ERR_NO_ERROR);
error->code = code;
_PyXI_excinfo_Clear(&error->uncaught);
}
return failure;
}
PyObject *
_PyXI_ApplyError(_PyXI_error *error)
{
if (error->code == _PyXI_ERR_UNCAUGHT_EXCEPTION) {
// Raise an exception that proxies the propagated exception.
return _PyXI_excinfo_AsObject(&error->uncaught);
}
else if (error->code == _PyXI_ERR_NOT_SHAREABLE) {
// Propagate the exception directly.
_set_xid_lookup_failure(error->interp, NULL, error->uncaught.msg);
}
else {
// Raise an exception corresponding to the code.
assert(error->code != _PyXI_ERR_NO_ERROR);
(void)_PyXI_ApplyErrorCode(error->code, error->interp);
if (error->uncaught.type.name != NULL || error->uncaught.msg != NULL) {
// __context__ will be set to a proxy of the propagated exception.
PyObject *exc = PyErr_GetRaisedException();
_PyXI_excinfo_Apply(&error->uncaught, PyExc_InterpreterError);
PyObject *exc2 = PyErr_GetRaisedException();
PyException_SetContext(exc, exc2);
PyErr_SetRaisedException(exc);
}
}
assert(PyErr_Occurred());
return NULL;
}
/* shared namespaces */
/* Shared namespaces are expected to have relatively short lifetimes.
This means dealloc of a shared namespace will normally happen "soon".
Namespace items hold cross-interpreter data, which must get released.
If the namespace/items are cleared in a different interpreter than
where the items' cross-interpreter data was set then that will cause
pending calls to be used to release the cross-interpreter data.
The tricky bit is that the pending calls can happen sufficiently
later that the namespace/items might already be deallocated. This is
a problem if the cross-interpreter data is allocated as part of a
namespace item. If that's the case then we must ensure the shared
namespace is only cleared/freed *after* that data has been released. */
typedef struct _sharednsitem {
const char *name;
_PyCrossInterpreterData *data;
// We could have a "PyCrossInterpreterData _data" field, so it would
// be allocated as part of the item and avoid an extra allocation.
// However, doing so adds a bunch of complexity because we must
// ensure the item isn't freed before a pending call might happen
// in a different interpreter to release the XI data.
} _PyXI_namespace_item;
static int
_sharednsitem_is_initialized(_PyXI_namespace_item *item)
{
if (item->name != NULL) {
return 1;
}
return 0;
}
static int
_sharednsitem_init(_PyXI_namespace_item *item, PyObject *key)
{
item->name = _copy_string_obj_raw(key, NULL);
if (item->name == NULL) {
assert(!_sharednsitem_is_initialized(item));
return -1;
}
item->data = NULL;
assert(_sharednsitem_is_initialized(item));
return 0;
}
static int
_sharednsitem_has_value(_PyXI_namespace_item *item, int64_t *p_interpid)
{
if (item->data == NULL) {
return 0;
}
if (p_interpid != NULL) {
*p_interpid = _PyCrossInterpreterData_INTERPID(item->data);
}
return 1;
}
static int
_sharednsitem_set_value(_PyXI_namespace_item *item, PyObject *value)
{
assert(_sharednsitem_is_initialized(item));
assert(item->data == NULL);
item->data = PyMem_RawMalloc(sizeof(_PyCrossInterpreterData));
if (item->data == NULL) {
PyErr_NoMemory();
return -1;
}
if (_PyObject_GetCrossInterpreterData(value, item->data) != 0) {
PyMem_RawFree(item->data);
item->data = NULL;
// The caller may want to propagate PyExc_NotShareableError
// if currently switched between interpreters.
return -1;
}
return 0;
}
static void
_sharednsitem_clear_value(_PyXI_namespace_item *item)
{
_PyCrossInterpreterData *data = item->data;
if (data != NULL) {
item->data = NULL;
int rawfree = 1;
(void)_release_xid_data(data, rawfree);
}
}
static void
_sharednsitem_clear(_PyXI_namespace_item *item)
{
if (item->name != NULL) {
PyMem_RawFree((void *)item->name);
item->name = NULL;
}
_sharednsitem_clear_value(item);
}
static int
_sharednsitem_copy_from_ns(struct _sharednsitem *item, PyObject *ns)
{
assert(item->name != NULL);
assert(item->data == NULL);
PyObject *value = PyDict_GetItemString(ns, item->name); // borrowed
if (value == NULL) {
if (PyErr_Occurred()) {
return -1;
}
// When applied, this item will be set to the default (or fail).
return 0;
}
if (_sharednsitem_set_value(item, value) < 0) {
return -1;
}
return 0;
}
static int
_sharednsitem_apply(_PyXI_namespace_item *item, PyObject *ns, PyObject *dflt)
{
PyObject *name = PyUnicode_FromString(item->name);
if (name == NULL) {
return -1;
}
PyObject *value;
if (item->data != NULL) {
value = _PyCrossInterpreterData_NewObject(item->data);
if (value == NULL) {
Py_DECREF(name);
return -1;
}
}
else {
value = Py_NewRef(dflt);
}
int res = PyDict_SetItem(ns, name, value);
Py_DECREF(name);
Py_DECREF(value);
return res;
}
struct _sharedns {
Py_ssize_t len;
_PyXI_namespace_item *items;
};
static _PyXI_namespace *
_sharedns_new(void)
{
_PyXI_namespace *ns = PyMem_RawCalloc(sizeof(_PyXI_namespace), 1);
if (ns == NULL) {
PyErr_NoMemory();
return NULL;
}
*ns = (_PyXI_namespace){ 0 };
return ns;
}
static int
_sharedns_is_initialized(_PyXI_namespace *ns)
{
if (ns->len == 0) {
assert(ns->items == NULL);
return 0;
}
assert(ns->len > 0);
assert(ns->items != NULL);
assert(_sharednsitem_is_initialized(&ns->items[0]));
assert(ns->len == 1
|| _sharednsitem_is_initialized(&ns->items[ns->len - 1]));
return 1;
}
#define HAS_COMPLETE_DATA 1
#define HAS_PARTIAL_DATA 2
static int
_sharedns_has_xidata(_PyXI_namespace *ns, int64_t *p_interpid)
{
// We expect _PyXI_namespace to always be initialized.
assert(_sharedns_is_initialized(ns));
int res = 0;
_PyXI_namespace_item *item0 = &ns->items[0];
if (!_sharednsitem_is_initialized(item0)) {
return 0;
}
int64_t interpid0 = -1;
if (!_sharednsitem_has_value(item0, &interpid0)) {
return 0;
}
if (ns->len > 1) {
// At this point we know it is has at least partial data.
_PyXI_namespace_item *itemN = &ns->items[ns->len-1];
if (!_sharednsitem_is_initialized(itemN)) {
res = HAS_PARTIAL_DATA;
goto finally;
}
int64_t interpidN = -1;
if (!_sharednsitem_has_value(itemN, &interpidN)) {
res = HAS_PARTIAL_DATA;
goto finally;
}
assert(interpidN == interpid0);
}
res = HAS_COMPLETE_DATA;
*p_interpid = interpid0;
finally:
return res;
}
static void
_sharedns_clear(_PyXI_namespace *ns)
{
if (!_sharedns_is_initialized(ns)) {
return;
}
// If the cross-interpreter data were allocated as part of
// _PyXI_namespace_item (instead of dynamically), this is where
// we would need verify that we are clearing the items in the
// correct interpreter, to avoid a race with releasing the XI data
// via a pending call. See _sharedns_has_xidata().
for (Py_ssize_t i=0; i < ns->len; i++) {
_sharednsitem_clear(&ns->items[i]);
}
PyMem_RawFree(ns->items);
ns->items = NULL;
ns->len = 0;
}
static void
_sharedns_free(_PyXI_namespace *ns)
{
_sharedns_clear(ns);
PyMem_RawFree(ns);
}
static int
_sharedns_init(_PyXI_namespace *ns, PyObject *names)
{
assert(!_sharedns_is_initialized(ns));
assert(names != NULL);
Py_ssize_t len = PyDict_CheckExact(names)
? PyDict_Size(names)
: PySequence_Size(names);
if (len < 0) {
return -1;
}
if (len == 0) {
PyErr_SetString(PyExc_ValueError, "empty namespaces not allowed");
return -1;
}
assert(len > 0);
// Allocate the items.
_PyXI_namespace_item *items =
PyMem_RawCalloc(sizeof(struct _sharednsitem), len);
if (items == NULL) {
PyErr_NoMemory();
return -1;
}
// Fill in the names.
Py_ssize_t i = -1;
if (PyDict_CheckExact(names)) {
Py_ssize_t pos = 0;
for (i=0; i < len; i++) {
PyObject *key;
if (!PyDict_Next(names, &pos, &key, NULL)) {
// This should not be possible.
assert(0);
goto error;
}
if (_sharednsitem_init(&items[i], key) < 0) {
goto error;
}
}
}
else if (PySequence_Check(names)) {
for (i=0; i < len; i++) {
PyObject *key = PySequence_GetItem(names, i);
if (key == NULL) {
goto error;
}
int res = _sharednsitem_init(&items[i], key);
Py_DECREF(key);
if (res < 0) {
goto error;
}
}
}
else {
PyErr_SetString(PyExc_NotImplementedError,
"non-sequence namespace not supported");
goto error;
}
ns->items = items;
ns->len = len;
assert(_sharedns_is_initialized(ns));
return 0;
error:
for (Py_ssize_t j=0; j < i; j++) {
_sharednsitem_clear(&items[j]);
}
PyMem_RawFree(items);
assert(!_sharedns_is_initialized(ns));
return -1;
}
void
_PyXI_FreeNamespace(_PyXI_namespace *ns)
{
if (!_sharedns_is_initialized(ns)) {
return;
}
int64_t interpid = -1;
if (!_sharedns_has_xidata(ns, &interpid)) {
_sharedns_free(ns);
return;
}
if (interpid == PyInterpreterState_GetID(PyInterpreterState_Get())) {
_sharedns_free(ns);
}
else {
// If we weren't always dynamically allocating the cross-interpreter
// data in each item then we would need to using a pending call
// to call _sharedns_free(), to avoid the race between freeing
// the shared namespace and releasing the XI data.
_sharedns_free(ns);
}
}
_PyXI_namespace *
_PyXI_NamespaceFromNames(PyObject *names)
{
if (names == NULL || names == Py_None) {
return NULL;
}
_PyXI_namespace *ns = _sharedns_new();
if (ns == NULL) {
return NULL;
}
if (_sharedns_init(ns, names) < 0) {
PyMem_RawFree(ns);
if (PySequence_Size(names) == 0) {
PyErr_Clear();
}
return NULL;
}
return ns;
}
#ifndef NDEBUG
static int _session_is_active(_PyXI_session *);
#endif
static void _propagate_not_shareable_error(_PyXI_session *);
int
_PyXI_FillNamespaceFromDict(_PyXI_namespace *ns, PyObject *nsobj,
_PyXI_session *session)
{
// session must be entered already, if provided.
assert(session == NULL || _session_is_active(session));
assert(_sharedns_is_initialized(ns));
for (Py_ssize_t i=0; i < ns->len; i++) {
_PyXI_namespace_item *item = &ns->items[i];
if (_sharednsitem_copy_from_ns(item, nsobj) < 0) {
_propagate_not_shareable_error(session);
// Clear out the ones we set so far.
for (Py_ssize_t j=0; j < i; j++) {
_sharednsitem_clear_value(&ns->items[j]);
}
return -1;
}
}
return 0;
}
// All items are expected to be shareable.
static _PyXI_namespace *
_PyXI_NamespaceFromDict(PyObject *nsobj, _PyXI_session *session)
{
// session must be entered already, if provided.
assert(session == NULL || _session_is_active(session));
if (nsobj == NULL || nsobj == Py_None) {
return NULL;
}
if (!PyDict_CheckExact(nsobj)) {
PyErr_SetString(PyExc_TypeError, "expected a dict");
return NULL;
}
_PyXI_namespace *ns = _sharedns_new();
if (ns == NULL) {
return NULL;
}
if (_sharedns_init(ns, nsobj) < 0) {
if (PyDict_Size(nsobj) == 0) {
PyMem_RawFree(ns);
PyErr_Clear();
return NULL;
}
goto error;
}
if (_PyXI_FillNamespaceFromDict(ns, nsobj, session) < 0) {
goto error;
}
return ns;
error:
assert(PyErr_Occurred()
|| (session != NULL && session->error_override != NULL));
_sharedns_free(ns);
return NULL;
}
int
_PyXI_ApplyNamespace(_PyXI_namespace *ns, PyObject *nsobj, PyObject *dflt)
{
for (Py_ssize_t i=0; i < ns->len; i++) {
if (_sharednsitem_apply(&ns->items[i], nsobj, dflt) != 0) {
return -1;
}
}
return 0;
}
/**********************/
/* high-level helpers */
/**********************/
/* enter/exit a cross-interpreter session */
static void
_enter_session(_PyXI_session *session, PyInterpreterState *interp)
{
// Set here and cleared in _exit_session().
assert(!session->own_init_tstate);
assert(session->init_tstate == NULL);
assert(session->prev_tstate == NULL);
// Set elsewhere and cleared in _exit_session().
assert(!session->running);
assert(session->main_ns == NULL);
// Set elsewhere and cleared in _capture_current_exception().
assert(session->error_override == NULL);
// Set elsewhere and cleared in _PyXI_ApplyCapturedException().
assert(session->error == NULL);
// Switch to interpreter.
PyThreadState *tstate = PyThreadState_Get();
PyThreadState *prev = tstate;
if (interp != tstate->interp) {
tstate = PyThreadState_New(interp);
_PyThreadState_SetWhence(tstate, _PyThreadState_WHENCE_EXEC);
// XXX Possible GILState issues?
session->prev_tstate = PyThreadState_Swap(tstate);
assert(session->prev_tstate == prev);
session->own_init_tstate = 1;
}
session->init_tstate = tstate;
session->prev_tstate = prev;
}
static void
_exit_session(_PyXI_session *session)
{
PyThreadState *tstate = session->init_tstate;
assert(tstate != NULL);
assert(PyThreadState_Get() == tstate);
// Release any of the entered interpreters resources.
if (session->main_ns != NULL) {
Py_CLEAR(session->main_ns);
}
// Ensure this thread no longer owns __main__.
if (session->running) {
_PyInterpreterState_SetNotRunningMain(tstate->interp);
assert(!PyErr_Occurred());
session->running = 0;
}
// Switch back.
assert(session->prev_tstate != NULL);
if (session->prev_tstate != session->init_tstate) {
assert(session->own_init_tstate);
session->own_init_tstate = 0;
PyThreadState_Clear(tstate);
PyThreadState_Swap(session->prev_tstate);
PyThreadState_Delete(tstate);
}
else {
assert(!session->own_init_tstate);
}
session->prev_tstate = NULL;
session->init_tstate = NULL;
}
#ifndef NDEBUG
static int
_session_is_active(_PyXI_session *session)
{
return (session->init_tstate != NULL);
}
#endif
static void
_propagate_not_shareable_error(_PyXI_session *session)
{
if (session == NULL) {
return;
}
PyInterpreterState *interp = PyInterpreterState_Get();
if (PyErr_ExceptionMatches(_get_not_shareable_error_type(interp))) {
// We want to propagate the exception directly.
session->_error_override = _PyXI_ERR_NOT_SHAREABLE;
session->error_override = &session->_error_override;
}
}
static void
_capture_current_exception(_PyXI_session *session)
{
assert(session->error == NULL);
if (!PyErr_Occurred()) {
assert(session->error_override == NULL);
return;
}
// Handle the exception override.
_PyXI_errcode *override = session->error_override;
session->error_override = NULL;
_PyXI_errcode errcode = override != NULL
? *override
: _PyXI_ERR_UNCAUGHT_EXCEPTION;
// Pop the exception object.
PyObject *excval = NULL;
if (errcode == _PyXI_ERR_UNCAUGHT_EXCEPTION) {
// We want to actually capture the current exception.
excval = PyErr_GetRaisedException();
}
else if (errcode == _PyXI_ERR_ALREADY_RUNNING) {
// We don't need the exception info.
PyErr_Clear();
}
else {
// We could do a variety of things here, depending on errcode.
// However, for now we simply capture the exception and save
// the errcode.
excval = PyErr_GetRaisedException();
}
// Capture the exception.
_PyXI_error *err = &session->_error;
*err = (_PyXI_error){
.interp = session->init_tstate->interp,
};
const char *failure;
if (excval == NULL) {
failure = _PyXI_InitError(err, NULL, errcode);
}
else {
failure = _PyXI_InitError(err, excval, _PyXI_ERR_UNCAUGHT_EXCEPTION);
Py_DECREF(excval);
if (failure == NULL && override != NULL) {
err->code = errcode;
}
}
// Handle capture failure.
if (failure != NULL) {
// XXX Make this error message more generic.
fprintf(stderr,
"RunFailedError: script raised an uncaught exception (%s)",
failure);
err = NULL;
}
// Finished!
assert(!PyErr_Occurred());
session->error = err;
}
PyObject *
_PyXI_ApplyCapturedException(_PyXI_session *session)
{
assert(!PyErr_Occurred());
assert(session->error != NULL);
PyObject *res = _PyXI_ApplyError(session->error);
assert((res == NULL) != (PyErr_Occurred() == NULL));
session->error = NULL;
return res;
}
int
_PyXI_HasCapturedException(_PyXI_session *session)
{
return session->error != NULL;
}
int
_PyXI_Enter(_PyXI_session *session,
PyInterpreterState *interp, PyObject *nsupdates)
{
// Convert the attrs for cross-interpreter use.
_PyXI_namespace *sharedns = NULL;
if (nsupdates != NULL) {
sharedns = _PyXI_NamespaceFromDict(nsupdates, NULL);
if (sharedns == NULL && PyErr_Occurred()) {
assert(session->error == NULL);
return -1;
}
}
// Switch to the requested interpreter (if necessary).
_enter_session(session, interp);
_PyXI_errcode errcode = _PyXI_ERR_UNCAUGHT_EXCEPTION;
// Ensure this thread owns __main__.
if (_PyInterpreterState_SetRunningMain(interp) < 0) {
// In the case where we didn't switch interpreters, it would
// be more efficient to leave the exception in place and return
// immediately. However, life is simpler if we don't.
errcode = _PyXI_ERR_ALREADY_RUNNING;
goto error;
}
session->running = 1;
// Cache __main__.__dict__.
PyObject *main_mod = PyUnstable_InterpreterState_GetMainModule(interp);
if (main_mod == NULL) {
errcode = _PyXI_ERR_MAIN_NS_FAILURE;
goto error;
}
PyObject *ns = PyModule_GetDict(main_mod); // borrowed
Py_DECREF(main_mod);
if (ns == NULL) {
errcode = _PyXI_ERR_MAIN_NS_FAILURE;
goto error;
}
session->main_ns = Py_NewRef(ns);
// Apply the cross-interpreter data.
if (sharedns != NULL) {
if (_PyXI_ApplyNamespace(sharedns, ns, NULL) < 0) {
errcode = _PyXI_ERR_APPLY_NS_FAILURE;
goto error;
}
_PyXI_FreeNamespace(sharedns);
}
errcode = _PyXI_ERR_NO_ERROR;
assert(!PyErr_Occurred());
return 0;
error:
assert(PyErr_Occurred());
// We want to propagate all exceptions here directly (best effort).
assert(errcode != _PyXI_ERR_UNCAUGHT_EXCEPTION);
session->error_override = &errcode;
_capture_current_exception(session);
_exit_session(session);
if (sharedns != NULL) {
_PyXI_FreeNamespace(sharedns);
}
return -1;
}
void
_PyXI_Exit(_PyXI_session *session)
{
_capture_current_exception(session);
_exit_session(session);
}
/*********************/
/* runtime lifecycle */
/*********************/
PyStatus
_PyXI_Init(PyInterpreterState *interp)
{
// Initialize the XID lookup state (e.g. registry).
xid_lookup_init(interp);
// Initialize exceptions (heap types).
if (_init_not_shareable_error_type(interp) < 0) {
return _PyStatus_ERR("failed to initialize NotShareableError");
}
return _PyStatus_OK();
}
// _PyXI_Fini() must be called before the interpreter is cleared,
// since we must clear some heap objects.
void
_PyXI_Fini(PyInterpreterState *interp)
{
// Finalize exceptions (heap types).
_fini_not_shareable_error_type(interp);
// Finalize the XID lookup state (e.g. registry).
xid_lookup_fini(interp);
}
PyStatus
_PyXI_InitTypes(PyInterpreterState *interp)
{
if (init_exceptions(interp) < 0) {
PyErr_PrintEx(0);
return _PyStatus_ERR("failed to initialize an exception type");
}
return _PyStatus_OK();
}
void
_PyXI_FiniTypes(PyInterpreterState *interp)
{
fini_exceptions(interp);
}
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