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[3.9] closes bpo-42938: Replace snprintf with Python unicode formatting in ctypes param reprs. #24247

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Merged
merged 1 commit into from
Jan 18, 2021
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[3.9] closes bpo-42938: Replace snprintf with Python unicode formatting in ctypes param reprs. #24247

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43 changes: 43 additions & 0 deletions Lib/ctypes/test/test_parameters.py
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Original file line number Diff line number Diff line change
Expand Up @@ -201,6 +201,49 @@ def __dict__(self):
with self.assertRaises(ZeroDivisionError):
WorseStruct().__setstate__({}, b'foo')

def test_parameter_repr(self):
from ctypes import (
c_bool,
c_char,
c_wchar,
c_byte,
c_ubyte,
c_short,
c_ushort,
c_int,
c_uint,
c_long,
c_ulong,
c_longlong,
c_ulonglong,
c_float,
c_double,
c_longdouble,
c_char_p,
c_wchar_p,
c_void_p,
)
self.assertRegex(repr(c_bool.from_param(True)), r"^<cparam '\?' at 0x[A-Fa-f0-9]+>$")
self.assertEqual(repr(c_char.from_param(97)), "<cparam 'c' ('a')>")
self.assertRegex(repr(c_wchar.from_param('a')), r"^<cparam 'u' at 0x[A-Fa-f0-9]+>$")
self.assertEqual(repr(c_byte.from_param(98)), "<cparam 'b' (98)>")
self.assertEqual(repr(c_ubyte.from_param(98)), "<cparam 'B' (98)>")
self.assertEqual(repr(c_short.from_param(511)), "<cparam 'h' (511)>")
self.assertEqual(repr(c_ushort.from_param(511)), "<cparam 'H' (511)>")
self.assertRegex(repr(c_int.from_param(20000)), r"^<cparam '[li]' \(20000\)>$")
self.assertRegex(repr(c_uint.from_param(20000)), r"^<cparam '[LI]' \(20000\)>$")
self.assertRegex(repr(c_long.from_param(20000)), r"^<cparam '[li]' \(20000\)>$")
self.assertRegex(repr(c_ulong.from_param(20000)), r"^<cparam '[LI]' \(20000\)>$")
self.assertRegex(repr(c_longlong.from_param(20000)), r"^<cparam '[liq]' \(20000\)>$")
self.assertRegex(repr(c_ulonglong.from_param(20000)), r"^<cparam '[LIQ]' \(20000\)>$")
self.assertEqual(repr(c_float.from_param(1.5)), "<cparam 'f' (1.5)>")
self.assertEqual(repr(c_double.from_param(1.5)), "<cparam 'd' (1.5)>")
self.assertEqual(repr(c_double.from_param(1e300)), "<cparam 'd' (1e+300)>")
self.assertRegex(repr(c_longdouble.from_param(1.5)), r"^<cparam ('d' \(1.5\)|'g' at 0x[A-Fa-f0-9]+)>$")
self.assertRegex(repr(c_char_p.from_param(b'hihi')), "^<cparam 'z' \(0x[A-Fa-f0-9]+\)>$")
self.assertRegex(repr(c_wchar_p.from_param('hihi')), "^<cparam 'Z' \(0x[A-Fa-f0-9]+\)>$")
self.assertRegex(repr(c_void_p.from_param(0x12)), r"^<cparam 'P' \(0x0*12\)>$")

################################################################

if __name__ == '__main__':
Expand Down
2 changes: 2 additions & 0 deletions Misc/NEWS.d/next/Security/2021-01-18-09-27-31.bpo-42938.4Zn4Mp.rst
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Original file line number Diff line number Diff line change
@@ -0,0 +1,2 @@
Avoid static buffers when computing the repr of :class:`ctypes.c_double` and
:class:`ctypes.c_longdouble` values.
51 changes: 19 additions & 32 deletions Modules/_ctypes/callproc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -489,58 +489,47 @@ is_literal_char(unsigned char c)
static PyObject *
PyCArg_repr(PyCArgObject *self)
{
char buffer[256];
switch(self->tag) {
case 'b':
case 'B':
sprintf(buffer, "<cparam '%c' (%d)>",
return PyUnicode_FromFormat("<cparam '%c' (%d)>",
self->tag, self->value.b);
break;
case 'h':
case 'H':
sprintf(buffer, "<cparam '%c' (%d)>",
return PyUnicode_FromFormat("<cparam '%c' (%d)>",
self->tag, self->value.h);
break;
case 'i':
case 'I':
sprintf(buffer, "<cparam '%c' (%d)>",
return PyUnicode_FromFormat("<cparam '%c' (%d)>",
self->tag, self->value.i);
break;
case 'l':
case 'L':
sprintf(buffer, "<cparam '%c' (%ld)>",
return PyUnicode_FromFormat("<cparam '%c' (%ld)>",
self->tag, self->value.l);
break;

case 'q':
case 'Q':
sprintf(buffer,
#ifdef MS_WIN32
"<cparam '%c' (%I64d)>",
#else
"<cparam '%c' (%lld)>",
#endif
return PyUnicode_FromFormat("<cparam '%c' (%lld)>",
self->tag, self->value.q);
break;
case 'd':
sprintf(buffer, "<cparam '%c' (%f)>",
self->tag, self->value.d);
break;
case 'f':
sprintf(buffer, "<cparam '%c' (%f)>",
self->tag, self->value.f);
break;

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

/* Hm, are these 'z' and 'Z' codes useful at all?
Shouldn't they be replaced by the functionality of c_string
Expand All @@ -549,22 +538,20 @@ PyCArg_repr(PyCArgObject *self)
case 'z':
case 'Z':
case 'P':
sprintf(buffer, "<cparam '%c' (%p)>",
return PyUnicode_FromFormat("<cparam '%c' (%p)>",
self->tag, self->value.p);
break;

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

static PyMemberDef PyCArgType_members[] = {
Expand Down