closes bpo-42938: Replace snprintf with Python unicode formatting in ctypes param reprs. (24239)

Author: benjaminp

Lib/ctypes/test/test_parameters.py

@@ -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__':

Misc/NEWS.d/next/Security/2021-01-18-09-27-31.bpo-42938.4Zn4Mp.rst

@@ -0,0 +1,2 @@
+Avoid static buffers when computing the repr of :class:`ctypes.c_double` and
+:class:`ctypes.c_longdouble` values.

Modules/_ctypes/callproc.c

@@ -487,58 +487,47 @@ 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
@@ -547,22 +536,20 @@ 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[] = {