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bpo-33817: Fix _PyString_Resize() and _PyUnicode_Resize() for empty s…

…trings. (GH-11515)
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serhiy-storchaka committed Jan 12, 2019
1 parent 0167c08 commit 08a81df05004147ee174ece645679576ab867860
@@ -474,8 +474,106 @@ def __rmod__(self, other):
self.assertEqual('lhs %% %r' % SubclassedStr('rhs'),
"Success, self.__rmod__('lhs %% %r') was called")


class CAPITest(unittest.TestCase):

# Test PyString_FromFormat()
def test_from_format(self):
ctypes = test_support.import_module('ctypes')
_testcapi = test_support.import_module('_testcapi')
from ctypes import pythonapi, py_object
from ctypes import (
c_int, c_uint,
c_long, c_ulong,
c_size_t, c_ssize_t,
c_char_p)

PyString_FromFormat = pythonapi.PyString_FromFormat
PyString_FromFormat.restype = py_object

# basic tests
self.assertEqual(PyString_FromFormat(b'format'),
b'format')
self.assertEqual(PyString_FromFormat(b'Hello %s !', b'world'),
b'Hello world !')

# test formatters
self.assertEqual(PyString_FromFormat(b'c=%c', c_int(0)),
b'c=\0')
self.assertEqual(PyString_FromFormat(b'c=%c', c_int(ord('@'))),
b'c=@')
self.assertEqual(PyString_FromFormat(b'c=%c', c_int(255)),
b'c=\xff')
self.assertEqual(PyString_FromFormat(b'd=%d ld=%ld zd=%zd',
c_int(1), c_long(2),
c_size_t(3)),
b'd=1 ld=2 zd=3')
self.assertEqual(PyString_FromFormat(b'd=%d ld=%ld zd=%zd',
c_int(-1), c_long(-2),
c_size_t(-3)),
b'd=-1 ld=-2 zd=-3')
self.assertEqual(PyString_FromFormat(b'u=%u lu=%lu zu=%zu',
c_uint(123), c_ulong(456),
c_size_t(789)),
b'u=123 lu=456 zu=789')
self.assertEqual(PyString_FromFormat(b'i=%i', c_int(123)),
b'i=123')
self.assertEqual(PyString_FromFormat(b'i=%i', c_int(-123)),
b'i=-123')
self.assertEqual(PyString_FromFormat(b'x=%x', c_int(0xabc)),
b'x=abc')

self.assertEqual(PyString_FromFormat(b's=%s', c_char_p(b'cstr')),
b's=cstr')

# test minimum and maximum integer values
size_max = c_size_t(-1).value
for formatstr, ctypes_type, value, py_formatter in (
(b'%d', c_int, _testcapi.INT_MIN, str),
(b'%d', c_int, _testcapi.INT_MAX, str),
(b'%ld', c_long, _testcapi.LONG_MIN, str),
(b'%ld', c_long, _testcapi.LONG_MAX, str),
(b'%lu', c_ulong, _testcapi.ULONG_MAX, str),
(b'%zd', c_ssize_t, _testcapi.PY_SSIZE_T_MIN, str),
(b'%zd', c_ssize_t, _testcapi.PY_SSIZE_T_MAX, str),
(b'%zu', c_size_t, size_max, str),
):
self.assertEqual(PyString_FromFormat(formatstr, ctypes_type(value)),
py_formatter(value).encode('ascii')),

# width and precision (width is currently ignored)
self.assertEqual(PyString_FromFormat(b'%5s', b'a'),
b'a')
self.assertEqual(PyString_FromFormat(b'%.3s', b'abcdef'),
b'abc')

# '%%' formatter
self.assertEqual(PyString_FromFormat(b'%%'),
b'%')
self.assertEqual(PyString_FromFormat(b'[%%]'),
b'[%]')
self.assertEqual(PyString_FromFormat(b'%%%c', c_int(ord('_'))),
b'%_')
self.assertEqual(PyString_FromFormat(b'%%s'),
b'%s')

# Invalid formats and partial formatting
self.assertEqual(PyString_FromFormat(b'%'), b'%')
self.assertEqual(PyString_FromFormat(b'x=%i y=%', c_int(2), c_int(3)),
b'x=2 y=%')

self.assertEqual(PyString_FromFormat(b'%c', c_int(-1)), b'\xff')
self.assertEqual(PyString_FromFormat(b'%c', c_int(256)), b'\0')

# Issue #33817: empty strings
self.assertEqual(PyString_FromFormat(b''),
b'')
self.assertEqual(PyString_FromFormat(b'%s', b''),
b'')


def test_main():
test_support.run_unittest(StrTest)
test_support.run_unittest(StrTest, CAPITest)

if __name__ == "__main__":
test_main()
@@ -1824,6 +1824,12 @@ def check_format(expected, format, *args):
check_format(u'%s',
b'%.%s', b'abc')

# Issue #33817: empty strings
check_format(u'',
b'')
check_format(u'',
b'%s', b'')

@test_support.cpython_only
def test_encode_decimal(self):
from _testcapi import unicode_encodedecimal
@@ -0,0 +1,4 @@
Fixed :c:func:`_PyString_Resize` and :c:func:`_PyUnicode_Resize` for empty
strings. This fixed also :c:func:`PyString_FromFormat` and
:c:func:`PyUnicode_FromFormat` when they return an empty string (e.g.
``PyString_FromFormat("%s", "")``).
@@ -3893,13 +3893,31 @@ _PyString_Resize(PyObject **pv, Py_ssize_t newsize)
register PyObject *v;
register PyStringObject *sv;
v = *pv;
if (!PyString_Check(v) || Py_REFCNT(v) != 1 || newsize < 0 ||
PyString_CHECK_INTERNED(v)) {
if (!PyString_Check(v) || newsize < 0) {
*pv = 0;
Py_DECREF(v);
PyErr_BadInternalCall();
return -1;
}
if (Py_SIZE(v) == 0) {
if (newsize == 0) {
return 0;
}
*pv = PyString_FromStringAndSize(NULL, newsize);
Py_DECREF(v);
return (*pv == NULL) ? -1 : 0;
}
if (Py_REFCNT(v) != 1 || PyString_CHECK_INTERNED(v)) {
*pv = 0;
Py_DECREF(v);
PyErr_BadInternalCall();
return -1;
}
if (newsize == 0) {
*pv = PyString_FromStringAndSize(NULL, 0);
Py_DECREF(v);
return (*pv == NULL) ? -1 : 0;
}
/* XXX UNREF/NEWREF interface should be more symmetrical */
_Py_DEC_REFTOTAL;
_Py_ForgetReference(v);
@@ -421,10 +421,27 @@ int _PyUnicode_Resize(PyUnicodeObject **unicode, Py_ssize_t length)
return -1;
}
v = *unicode;
if (v == NULL || !PyUnicode_Check(v) || Py_REFCNT(v) != 1 || length < 0) {
if (v == NULL || !PyUnicode_Check(v) || length < 0) {
PyErr_BadInternalCall();
return -1;
}
if (v->length == 0) {
if (length == 0) {
return 0;
}
*unicode = _PyUnicode_New(length);
Py_DECREF(v);
return (*unicode == NULL) ? -1 : 0;
}
if (Py_REFCNT(v) != 1) {
PyErr_BadInternalCall();
return -1;
}
if (length == 0) {
*unicode = _PyUnicode_New(0);
Py_DECREF(v);
return (*unicode == NULL) ? -1 : 0;
}

/* Resizing unicode_empty and single character objects is not
possible since these are being shared. We simply return a fresh

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