New submission from Vincent Michel:
The Bytearray type is a mutable object that support the read-write buffer
interface. The fcntl.ioctl() function is supposed to handle mutable object
(such as array.array) for the system calls in order to pass object that are
more than 1024 bytes long.
The problem is that in Python 2.7, Bytearray type is not supported as a mutable
object in the fcntl.ioctl function. In Python 3.2, it works perfectly.
In the specific case where a large C structure is needed (more than 1024
bytes), the Bytearray type is extremely useful compare to the array.array type
that is adapted for C arrays.
Example :
>>> file_handle = open('/dev/my_device')
>>> arg = bytearray()
>>> arg += pack('IL',1,2)
>>> command = 0
>>> ioctl(file_handle,command,arg)
Traceback (most recent call last):
File "<pyshell#22>", line 1, in <module>
ioctl(file_handle,command,arg)
TypeError: an integer is required
----------
components: IO
messages: 191110
nosy: vxgmichel
priority: normal
severity: normal
status: open
title: Bytearray type not supported as a mutable object in the fcntl.ioctl
function
type: behavior
versions: Python 2.7
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Python tracker <[email protected]>
<http://bugs.python.org/issue18209>
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