New submission from Larry Hastings:
The getxattr() system call retrieves an "extended attribute" on a file. When
you call it you pass in a buffer and a size. The expected behavior is, if you
pass in a buffer that's too small, the function returns -1 and sets errno to
ERANGE.
On a ZFS filesystem on Linux, using the "ZFS On Linux" port:
http://zfsonlinux.org/
getxattr() does not behave this way. Instead, it fills the buffer with the
first buffer-size bytes of data (without a zero terminator).
Python's implementation of getxattr() interprets this as success. Which means
that, the way it's implemented, if you call getxattr() to retrieve a value
that's > 128 bytes in length, you only get the first 128 bytes. (Happily, we
already have a regression test that finds this!)
Attached is a patch fixing this behavior. It checks the return value of
getxattr() to see if the buffer was filled to 100%. If so, it retries with a
larger buffer.
----------
assignee: larry
components: Library (Lib)
files: larry.setxattr.zfs.patch.1.txt
messages: 194716
nosy: larry
priority: normal
severity: normal
stage: patch review
status: open
title: getxattr on Linux ZFS native filesystem happily returns partial values
type: behavior
versions: Python 3.3, Python 3.4
Added file: http://bugs.python.org/file31203/larry.setxattr.zfs.patch.1.txt
_______________________________________
Python tracker <rep...@bugs.python.org>
<http://bugs.python.org/issue18694>
_______________________________________
_______________________________________________
Python-bugs-list mailing list
Unsubscribe:
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
