[Numpy-discussion] Deserialized arrays with base mutate strings

Hrvoje Niksic hrvoje.niksic@avl....
Wed Sep 23 03:01:11 CDT 2009

Pauli Virtanen wrote:
> Wed, 23 Sep 2009 09:15:44 +0200, Hrvoje Niksic wrote:
> [clip]
>> Numpy arrays with the "base" property are deserialized as arrays
>> pointing to a storage contained within a Python string.  This is a
>> problem since such arrays are mutable and can mutate existing strings.
>> Here is how to create one:
> Please file a bug ticket in the Trac, thanks!

Done - ticket #1233.

> Here is a simpler way, although one more difficult to accidentally:
>>>> a = numpy.frombuffer("A", dtype='S1')
>>>> a.flags.writeable = True
>>>> b = "A"
>>>> a[0] = "B"
>>>> b
> 'B'

I guess this one could be prevented by verifying that the buffer is 
writable when setting the "writable" flag.  When deserializing arrays, I 
don't see a reason for the "base" property to even exist - sharing of 
the buffer between different views is unpreserved anyway, as reported in 
my other thread.

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