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bpo-46323: Reduce stack usage of ctypes python callback function. (GH-31224)

This commit is contained in:
Dong-hee Na 2022-02-10 03:10:11 +09:00 committed by GitHub
parent bf2d44ffb0
commit d18120cd67
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3 changed files with 17 additions and 27 deletions
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3
Misc/NEWS.d/next/Core and Builtins/2022-02-10-02-29-12.bpo-46323.HK_cs0.rst Normal file
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@ -0,0 +1,3 @@
:mod:`ctypes` now allocates memory on the stack instead of on the heap
to pass arguments while calling a Python callback function.
Patch by Dong-hee Na.

35
Modules/_ctypes/callbacks.c
View File

@ -14,9 +14,18 @@
#include <stdbool.h>
#ifdef MS_WIN32
# include <malloc.h>
#endif
#include <ffi.h>
#include "ctypes.h"
#ifdef HAVE_ALLOCA_H
/* AIX needs alloca.h for alloca() */
#include <alloca.h>
#endif
/**************************************************************/
static void
@ -148,7 +157,6 @@ static void _CallPythonObject(void *mem,
void **pArgs)
{
PyObject *result = NULL;
PyObject **args = NULL;
Py_ssize_t i = 0, j = 0, nargs = 0;
PyObject *error_object = NULL;
int *space;
@ -156,24 +164,10 @@ static void _CallPythonObject(void *mem,
assert(PyTuple_Check(converters));
nargs = PyTuple_GET_SIZE(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;
}
PyObject *args_stack[CTYPES_MAX_ARGCOUNT];
if (nargs <= CTYPES_MAX_ARGCOUNT) {
args = args_stack;
}
else {
args = PyMem_Malloc(nargs * sizeof(PyObject *));
if (args == NULL) {
PyErr_NoMemory();
goto Done;
}
assert(nargs <= CTYPES_MAX_ARGCOUNT);
PyObject **args = NULL;
if (nargs > 0) {
args = alloca(nargs * sizeof(PyObject *));
}
PyObject **cnvs = PySequence_Fast_ITEMS(converters);
@ -310,9 +304,6 @@ static void _CallPythonObject(void *mem,
for (j = 0; j < i; j++) {
Py_DECREF(args[j]);
}
if (args != args_stack) {
PyMem_Free(args);
}
PyGILState_Release(state);
}

6
Modules/_ctypes/callproc.c
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@ -1162,11 +1162,7 @@ PyObject *_ctypes_callproc(PPROC pProc,
return NULL;
}
args = (struct argument *)alloca(sizeof(struct argument) * argcount);
if (!args) {
PyErr_NoMemory();
return NULL;
}
args = alloca(sizeof(struct argument) * argcount);
memset(args, 0, sizeof(struct argument) * argcount);
argtype_count = argtypes ? PyTuple_GET_SIZE(argtypes) : 0;
#ifdef MS_WIN32