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Merged
vstinner merged 2 commits into from
May 15, 2026
Merged

gh-148675: Use a string for ctypes cparam tag #149778

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f40bea4
gh-148675: Use a string for ctypes cparam tag
vstinner May 13, 2026
85808d5
Fix PyCArg_repr() for "q" and "Q" formats
vstinner May 13, 2026
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8 changes: 8 additions & 0 deletions Lib/test/test_ctypes/test_parameters.py
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Original file line numberDiff line numberDiff line change
@@ -1,6 +1,7 @@
import sys
import unittest
import test.support
import ctypes
from ctypes import (CDLL, PyDLL, ArgumentError,
Structure, Array, Union,
_Pointer, _SimpleCData, _CFuncPtr,
Expand DownExpand Up@@ -247,6 +248,13 @@ def test_parameter_repr(self):
self.assertRegex(repr(c_char_p.from_param(b'hihi')), r"^<cparam 'z' \(0x[A-Fa-f0-9]+\)>$")
self.assertRegex(repr(c_wchar_p.from_param('hihi')), r"^<cparam 'Z' \(0x[A-Fa-f0-9]+\)>$")
self.assertRegex(repr(c_void_p.from_param(0x12)), r"^<cparam 'P' \(0x0*12\)>$")
if hasattr(ctypes, 'c_double_complex'):
self.assertRegex(repr(ctypes.c_double_complex.from_param(0)),
r"^<cparam 'Zd' at 0x[A-Fa-f0-9]+>$")
self.assertRegex(repr(ctypes.c_float_complex.from_param(0)),
r"^<cparam 'Zf' at 0x[A-Fa-f0-9]+>$")
self.assertRegex(repr(ctypes.c_longdouble_complex.from_param(0)),
r"^<cparam 'Zg' at 0x[A-Fa-f0-9]+>$")

@test.support.cpython_only
def test_from_param_result_refcount(self):
Expand Down
32 changes: 17 additions & 15 deletions Modules/_ctypes/_ctypes.c
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Original file line numberDiff line numberDiff line change
Expand Up@@ -708,7 +708,7 @@ StructUnionType_paramfunc(ctypes_state *st, CDataObject *self)
}
assert(stginfo); /* Cannot be NULL for structure/union instances */

parg->tag = 'V';
parg->tag = "V";
parg->pffi_type = &stginfo->ffi_type_pointer;
parg->value.p = ptr;
parg->size = self->b_size;
Expand DownExpand Up@@ -1282,7 +1282,7 @@ PyCPointerType_paramfunc(ctypes_state *st, CDataObject *self)
if (parg == NULL)
return NULL;

parg->tag = 'P';
parg->tag = "P";
parg->pffi_type = &ffi_type_pointer;
parg->obj = Py_NewRef(self);
parg->value.p = *(void **)self->b_ptr;
Expand DownExpand Up@@ -1703,7 +1703,7 @@ PyCArrayType_paramfunc(ctypes_state *st, CDataObject *self)
PyCArgObject *p = PyCArgObject_new(st);
if (p == NULL)
return NULL;
p->tag = 'P';
p->tag = "P";
p->pffi_type = &ffi_type_pointer;
p->value.p = (char *)self->b_ptr;
p->obj = Py_NewRef(self);
Expand DownExpand Up@@ -1909,7 +1909,7 @@ c_wchar_p_from_param_impl(PyObject *type, PyTypeObject *cls, PyObject *value)
if (parg == NULL)
return NULL;
parg->pffi_type = &ffi_type_pointer;
parg->tag = 'Z';
parg->tag = "Z";
parg->obj = fd->setfunc(&parg->value, value, 0);
if (parg->obj == NULL) {
Py_DECREF(parg);
Expand DownExpand Up@@ -1998,7 +1998,7 @@ c_char_p_from_param_impl(PyObject *type, PyTypeObject *cls, PyObject *value)
if (parg == NULL)
return NULL;
parg->pffi_type = &ffi_type_pointer;
parg->tag = 'z';
parg->tag = "z";
parg->obj = fd->setfunc(&parg->value, value, 0);
if (parg->obj == NULL) {
Py_DECREF(parg);
Expand DownExpand Up@@ -2092,7 +2092,7 @@ c_void_p_from_param_impl(PyObject *type, PyTypeObject *cls, PyObject *value)
if (parg == NULL)
return NULL;
parg->pffi_type = &ffi_type_pointer;
parg->tag = 'P';
parg->tag = "P";
parg->obj = fd->setfunc(&parg->value, value, sizeof(void*));
if (parg->obj == NULL) {
Py_DECREF(parg);
Expand All@@ -2110,7 +2110,7 @@ c_void_p_from_param_impl(PyObject *type, PyTypeObject *cls, PyObject *value)
if (parg == NULL)
return NULL;
parg->pffi_type = &ffi_type_pointer;
parg->tag = 'z';
parg->tag = "z";
parg->obj = fd->setfunc(&parg->value, value, 0);
if (parg->obj == NULL) {
Py_DECREF(parg);
Expand All@@ -2127,7 +2127,7 @@ c_void_p_from_param_impl(PyObject *type, PyTypeObject *cls, PyObject *value)
if (parg == NULL)
return NULL;
parg->pffi_type = &ffi_type_pointer;
parg->tag = 'Z';
parg->tag = "Z";
parg->obj = fd->setfunc(&parg->value, value, 0);
if (parg->obj == NULL) {
Py_DECREF(parg);
Expand All@@ -2152,7 +2152,7 @@ c_void_p_from_param_impl(PyObject *type, PyTypeObject *cls, PyObject *value)
if (PyCArg_CheckExact(st, value)) {
/* byref(c_xxx()) */
PyCArgObject *a = (PyCArgObject *)value;
if (a->tag== 'P') {
if (strcmp(a->tag, "P") == 0) {
return Py_NewRef(value);
}
}
Expand All@@ -2165,7 +2165,7 @@ c_void_p_from_param_impl(PyObject *type, PyTypeObject *cls, PyObject *value)
if (parg == NULL)
return NULL;
parg->pffi_type = &ffi_type_pointer;
parg->tag = 'P';
parg->tag = "P";
Py_INCREF(value);
// Function pointers don't change their contents, no need to lock
parg->value.p = *(void **)func->b_ptr;
Expand All@@ -2191,7 +2191,7 @@ c_void_p_from_param_impl(PyObject *type, PyTypeObject *cls, PyObject *value)
if (parg == NULL)
return NULL;
parg->pffi_type = &ffi_type_pointer;
parg->tag = 'Z';
parg->tag = "Z";
parg->obj = Py_NewRef(value);
/* Remember: b_ptr points to where the pointer is stored! */
Py_BEGIN_CRITICAL_SECTION(value);
Expand DownExpand Up@@ -2332,7 +2332,8 @@ PyCSimpleType_paramfunc(ctypes_state *st, CDataObject *self)
if (parg == NULL)
return NULL;

parg->tag = fmt[0];
assert(strcmp(fd->code, fmt) == 0);
parg->tag = fd->code;
parg->pffi_type = fd->pffi_type;
parg->obj = Py_NewRef(self);
memcpy(&parg->value, self->b_ptr, self->b_size);
Expand DownExpand Up@@ -2578,7 +2579,8 @@ PyCSimpleType_from_param_impl(PyObject *type, PyTypeObject *cls,
if (parg == NULL)
return NULL;

parg->tag = fmt[0];
assert(strcmp(fd->code, fmt) == 0);
parg->tag = fd->code;
parg->pffi_type = fd->pffi_type;
parg->obj = fd->setfunc(&parg->value, value, info->size);
if (parg->obj)
Expand DownExpand Up@@ -2832,7 +2834,7 @@ PyCFuncPtrType_paramfunc(ctypes_state *st, CDataObject *self)
if (parg == NULL)
return NULL;

parg->tag = 'P';
parg->tag = "P";
parg->pffi_type = &ffi_type_pointer;
parg->obj = Py_NewRef(self);
parg->value.p = *(void **)self->b_ptr;
Expand DownExpand Up@@ -4303,7 +4305,7 @@ _byref(ctypes_state *st, PyObject *obj)
return NULL;
}

parg->tag = 'P';
parg->tag = "P";
parg->pffi_type = &ffi_type_pointer;
parg->obj = obj;
parg->value.p = ((CDataObject *)obj)->b_ptr;
Expand Down
45 changes: 23 additions & 22 deletions Modules/_ctypes/callproc.c
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Original file line numberDiff line numberDiff line change
Expand Up@@ -468,7 +468,7 @@ PyCArgObject_new(ctypes_state *st)
if (p == NULL)
return NULL;
p->pffi_type = NULL;
p->tag = '\0';
p->tag = "";
p->obj = NULL;
memset(&p->value, 0, sizeof(p->value));
PyObject_GC_Track(p);
Expand DownExpand Up@@ -512,45 +512,50 @@ static PyObject *
PyCArg_repr(PyObject *op)
{
PyCArgObject *self = _PyCArgObject_CAST(op);
switch(self->tag) {

if (strlen(self->tag) != 1) {
goto generic;
}

switch(self->tag[0]) {
case 'b':
case 'B':
return PyUnicode_FromFormat("<cparam '%c' (%d)>",
return PyUnicode_FromFormat("<cparam '%s' (%d)>",
self->tag, self->value.b);
case 'h':
case 'H':
return PyUnicode_FromFormat("<cparam '%c' (%d)>",
return PyUnicode_FromFormat("<cparam '%s' (%d)>",
self->tag, self->value.h);
case 'i':
case 'I':
return PyUnicode_FromFormat("<cparam '%c' (%d)>",
return PyUnicode_FromFormat("<cparam '%s' (%d)>",
self->tag, self->value.i);
case 'l':
case 'L':
return PyUnicode_FromFormat("<cparam '%c' (%ld)>",
return PyUnicode_FromFormat("<cparam '%s' (%ld)>",
self->tag, self->value.l);

case 'q':
case 'Q':
return PyUnicode_FromFormat("<cparam '%c' (%lld)>",
return PyUnicode_FromFormat("<cparam '%s' (%lld)>",
self->tag, self->value.q);
case 'd':
case 'f': {
PyObject *f = PyFloat_FromDouble((self->tag== 'f') ? self->value.f : self->value.d);
PyObject *f = PyFloat_FromDouble((strcmp(self->tag, "f") == 0) ? self->value.f : self->value.d);
if (f == NULL) {
return NULL;
}
PyObject *result = PyUnicode_FromFormat("<cparam '%c' (%R)>", self->tag, f);
PyObject *result = PyUnicode_FromFormat("<cparam '%s' (%R)>", self->tag, f);
Py_DECREF(f);
return result;
}
case 'c':
if (is_literal_char((unsigned char)self->value.c)) {
return PyUnicode_FromFormat("<cparam '%c' ('%c')>",
return PyUnicode_FromFormat("<cparam '%s' ('%c')>",
self->tag, self->value.c);
}
else {
return PyUnicode_FromFormat("<cparam '%c' ('\\x%02x')>",
return PyUnicode_FromFormat("<cparam '%s' ('\\x%02x')>",
self->tag, (unsigned char)self->value.c);
}

Expand All@@ -561,20 +566,16 @@ PyCArg_repr(PyObject *op)
case 'z':
case 'Z':
case 'P':
return PyUnicode_FromFormat("<cparam '%c' (%p)>",
return PyUnicode_FromFormat("<cparam '%s' (%p)>",
self->tag, self->value.p);
break;

default:
if (is_literal_char((unsigned char)self->tag)) {
return PyUnicode_FromFormat("<cparam '%c' at %p>",
(unsigned char)self->tag, (void *)self);
}
else {
return PyUnicode_FromFormat("<cparam 0x%02x at %p>",
(unsigned char)self->tag, (void *)self);
}
break;
}

generic:
return PyUnicode_FromFormat("<cparam '%s' at %p>",
self->tag, (void *)self);
}

static PyMemberDef PyCArgType_members[] = {
Expand DownExpand Up@@ -1807,7 +1808,7 @@ _ctypes_byref_impl(PyObject *module, PyObject *obj, Py_ssize_t offset)
if (parg == NULL)
return NULL;

parg->tag = 'P';
parg->tag = "P";
parg->pffi_type = &ffi_type_pointer;
parg->obj = Py_NewRef(obj);
parg->value.p = (char *)((CDataObject *)obj)->b_ptr + offset;
Expand Down
4 changes: 2 additions & 2 deletions Modules/_ctypes/ctypes.h
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Original file line numberDiff line numberDiff line change
Expand Up@@ -494,7 +494,7 @@ PyObject *_ctypes_callproc(ctypes_state *st,
struct tagPyCArgObject {
PyObject_HEAD
ffi_type *pffi_type;
char tag;
const char *tag;
union {
char c;
char b;
Expand All@@ -511,7 +511,7 @@ struct tagPyCArgObject {
long double G[2];
} value;
PyObject *obj;
Py_ssize_t size; /* for the 'V' tag */
Py_ssize_t size; /* for the "V" tag */
};

#define _PyCArgObject_CAST(op) ((PyCArgObject *)(op))
Expand Down
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