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bpo-40638: Check for attribute lookup failure in builtin_input_impl #20125

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bpo-40638: Check for attribute lookup failure in builtin_input_impl #20125

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24 changes: 24 additions & 0 deletions Lib/test/test_builtin.py
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Original file line number Diff line number Diff line change
Expand Up @@ -75,6 +75,23 @@ class BitBucket:
def write(self, line):
pass

class MalformedInputStream:
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"Malformed" in what way? I think this name could be better.

Suggested change
class MalformedInputStream:
class InputStreamWithReadlineButNoRead:

def readline(self):
return "foobar\n"

def fileno(self):
return 0

class MalformedOutputStream:
def __init__(self):
self.value = ""

def fileno(self):
return 1

def write(self, value):
self.value += value

test_conv_no_sign = [
('0', 0),
('1', 1),
Expand Down Expand Up @@ -1302,6 +1319,13 @@ def test_input(self):
sys.stdin = io.StringIO()
self.assertRaises(EOFError, input)

# input() in tty mode with a malformed input stream should attempt
# to call .readline()
sys.stdin = MalformedInputStream()
sys.stdout = MalformedOutputStream()
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Have you considered using a StringIO object for sys.stdout here?

self.assertEqual(input("baz"), "foobar") # strips \n
self.assertEqual(sys.stdout.value, "baz")

Comment on lines +1322 to +1328
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Having this here is slightly confusing, as it appears like it may affect the following assertion as well. Perhaps put this at the end of this method or in a separate method.

del sys.stdout
self.assertRaises(RuntimeError, input, 'prompt')
del sys.stdin
Expand Down
18 changes: 12 additions & 6 deletions Python/bltinmodule.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2010,17 +2010,21 @@ builtin_input_impl(PyObject *module, PyObject *prompt)

/* stdin is a text stream, so it must have an encoding. */
stdin_encoding = _PyObject_GetAttrId(fin, &PyId_encoding);
if (!stdin_encoding || !PyUnicode_Check(stdin_encoding)) {
goto _readline_disable_tty_and_fall_back;
}
stdin_errors = _PyObject_GetAttrId(fin, &PyId_errors);
if (!stdin_encoding || !stdin_errors ||
!PyUnicode_Check(stdin_encoding) ||
!PyUnicode_Check(stdin_errors)) {
tty = 0;
goto _readline_errors;
if (!stdin_errors || !PyUnicode_Check(stdin_errors)) {
goto _readline_disable_tty_and_fall_back;
}
stdin_encoding_str = PyUnicode_AsUTF8(stdin_encoding);
if (!stdin_encoding_str) {
goto _readline_errors;
}
stdin_errors_str = PyUnicode_AsUTF8(stdin_errors);
if (!stdin_encoding_str || !stdin_errors_str)
if (!stdin_errors_str) {
goto _readline_errors;
}
tmp = _PyObject_CallMethodIdNoArgs(fout, &PyId_flush);
if (tmp == NULL)
PyErr_Clear();
Expand Down Expand Up @@ -2099,6 +2103,8 @@ builtin_input_impl(PyObject *module, PyObject *prompt)

return result;

_readline_disable_tty_and_fall_back:
tty = 0;
_readline_errors:
Py_XDECREF(stdin_encoding);
Py_XDECREF(stdout_encoding);
Expand Down