[issue5395] array.fromfile not checking I/O errors
Eduardo Aguiar added the comment: Maybe you could create a file without read permission (000) and try to read from it. -- ___ Python tracker <http://bugs.python.org/issue5395> ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
[issue5395] array.fromfile not checking I/O errors
Eduardo Aguiar added the comment:
Another try. I have opened a file for writing, and have tried to read
from it:
>>> fp = open ('xxx', 'w')
>>> fp.read ()
Traceback (most recent call last):
File "", line 1, in
IOError: [Errno 9] Bad file descriptor
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[issue5395] array.fromfile not checking I/O errors
New submission from Eduardo Aguiar :
At arraymodule.c (line 1258):
nread = fread(item + (Py_SIZE(self) - n) * itemsize,
itemsize, n, fp);
if (nread < (size_t)n) {
Py_SIZE(self) -= (n - nread);
PyMem_RESIZE(item, char, Py_SIZE(self)*itemsize);
self->ob_item = item;
self->allocated = Py_SIZE(self);
PyErr_SetString(PyExc_EOFError,
"not enough items in file");
return NULL;
}
When fread returns 0, ferror should be called to check if it was an EOF
or an error condition. It is not handling OSErrors, such as I/O errors,
raising always "not enough items in file".
--
components: Library (Lib)
messages: 82936
nosy: aguiar
severity: normal
status: open
title: array.fromfile not checking I/O errors
type: behavior
versions: Python 2.6
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[issue5396] os.read not handling O_DIRECT flag
New submission from Eduardo Aguiar :
At posixmodule.c (line 6306)
static PyObject *
posix_read(PyObject *self, PyObject *args)
{
int fd, size, n;
PyObject *buffer;
if (!PyArg_ParseTuple(args, "ii:read", &fd, &size))
return NULL;
if (size < 0) {
errno = EINVAL;
return posix_error();
}
buffer = PyString_FromStringAndSize((char *)NULL, size);
if (buffer == NULL)
return NULL;
Py_BEGIN_ALLOW_THREADS
n = read(fd, PyString_AsString(buffer), size);
Py_END_ALLOW_THREADS
if (n < 0) {
Py_DECREF(buffer);
return posix_error();
}
if (n != size)
_PyString_Resize(&buffer, n);
return buffer;
}
os.read does not work with O_DIRECT flag. It fails with errno = EINVAL.
>From read(2) man page:
EINVAL fd is attached to an object which is unsuitable for
reading; or
the file was opened with the O_DIRECT flag, and
either the
address specified in buf, the value specified in count,
or the
current file offset is not suitably aligned.
if os.open is called with O_DIRECT flag enabled, the buffer used in
"read" must be page aligned and "size" must be multiple of pagesize also.
--
components: Library (Lib)
messages: 82938
nosy: aguiar
severity: normal
status: open
title: os.read not handling O_DIRECT flag
type: behavior
versions: Python 2.6
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[issue5396] os.read not handling O_DIRECT flag
Eduardo Aguiar added the comment: Hi, I think I have a few more issues you can consider: 1) to allocated an aligned buffer it is as simple as allocate 4096 + len (buffer) and truncate address to 4k boundary. 2) I wrote a floppy imager, and without O_DIRECT, it gives me 8 sectors (4k = kernel page) errors whenever one sector is bad. 3) There is os.O_DIRECT and os.open help page references it Best regards, Eduardo Aguiar -- ___ Python tracker <http://bugs.python.org/issue5396> ___ ___ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
