[New-bugs-announce] [issue1422] Writing to an invalid fd doesn't raise an exception

[Christian Heimes]

New submission from Christian Heimes:

The bug is related to http://bugs.python.org/issue1415 and occurs only
with the latest patch from #1415.

Writing to an invalid fd doesn't raise an exception:

>>> f = open(100, 'w')
>>> f.fileno()
100
>>> f.write("test")
4

However reading or opening an invalid fd for reading and writing raises
an exception.

>>> f = open(100, 'r')
>>> f.read()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/heimes/dev/python/py3k/Lib/io.py", line 1253, in read
    res += decoder.decode(self.buffer.read(), True)
  File "/home/heimes/dev/python/py3k/Lib/io.py", line 756, in read
    current = self.raw.read(to_read)
IOError: [Errno 9] Bad file descriptor
>>> f = open(100, 'w+')
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/home/heimes/dev/python/py3k/Lib/io.py", line 195, in __new__
    return open(*args, **kwargs)
  File "/home/heimes/dev/python/py3k/Lib/io.py", line 169, in open
    buffer = BufferedRandom(raw, buffering)
  File "/home/heimes/dev/python/py3k/Lib/io.py", line 948, in __init__
    raw._checkSeekable()
  File "/home/heimes/dev/python/py3k/Lib/io.py", line 301, in _checkSeekable
    if msg is None else msg)
IOError: File or stream is not seekable.

I expected that fileio_write() raises an exception when fd is invalid:

        n = write(self->fd, ptr, n);
        if (n < 0) {
                if (errno == EAGAIN)
                        Py_RETURN_NONE;
                PyErr_SetFromErrno(PyExc_IOError);
                return NULL;
        }

----------
assignee: tiran
components: Interpreter Core
keywords: py3k
messages: 57372
nosy: tiran
priority: normal
severity: normal
status: open
title: Writing to an invalid fd doesn't raise an exception
type: behavior
versions: Python 3.0

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Tracker <report at bugs.python.org>
<http://bugs.python.org/issue1422>
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