New submission from STINNER Victor <victor.stin...@haypocalc.com>: mmap, buffer, bytearray, string and unicode objects set the char buffer callback (bf_getcharbuffer). The bytearray object sets also the release buffer callback (bf_releasebuffer).
In Python 2.7, PyObject_AsCharBuffer() accepts bytearray objects, whereas the "t#" format of PyArg_Parse functions rejects byte bytearray objects (expect an "pinned buffer object"). In Python 3.2, PyObject_AsCharBuffer() releases the buffer. PyObject_AsCharBuffer() documentation (in 2.7 and 3.2) says that the function only accepts read-only objects. Something is wrong here. If the caller doesn't hold a kind of lock, the object cannot be protected against futher modifications. The caller has to ensure that the object is not modifiable until it finishs to use the char* pointer. I think that it would be safer to respect the documentation: PyObject_AsCharBuffer() should only accept read-only objects. The most important change is that functions using PyObject_AsCharBuffer() will not accept bytearray objects anymore. Attached patch (for Python 2.7) changes PyObject_AsCharBuffer() to reject modifiable objects. It removes also the character buffer callback from the bytearray type. To avoid breaking compatibility too much, I patched int(), long() and float() to still support bytearray objects. Examples of functions rejecting bytearray with the patch: - int(), long(), float(), complex() - many str methods: split, partition, rpartition, rsplit, index, find, count, translate, replace, startswith, endswith - writelines() of file objects (eg. sys.stdout.writelines) - writelines() method of a bz2 file -- My patch breaks backward compatibility, and I don't know that it is acceptable in Python 2.7. I will write a similar patch for Python 3.2. ---------- components: Interpreter Core files: PyObject_AsCharBuffer-2.7.patch keywords: patch messages: 113895 nosy: haypo, pitrou priority: normal severity: normal status: open title: PyObject_AsCharBuffer() should only accept read-only objects versions: Python 2.7, Python 3.2 Added file: http://bugs.python.org/file18523/PyObject_AsCharBuffer-2.7.patch _______________________________________ Python tracker <rep...@bugs.python.org> <http://bugs.python.org/issue9602> _______________________________________ _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
