[Numpy-discussion] numarray CVS seems to have an __array_struct__ bug

Todd Miller jmiller at stsci.edu
Thu Nov 17 04:15:03 CST 2005


Nice catch Andrew,  and very timely!

Thanks,
Todd

Andrew Straw wrote:

>Hi,
>
>I think there's a bug in the new __array_struct__ code in numarray CVS.
>
>Consider an object a which implements the __array_struct__ interface. If
>one constructs a numarray "view" of this array using aview =
>numarray.asarray(a), the numarray.ndarray instance does not keep a
>reference to a.__array_struct__. Thus, a segfault may occur because
>a.data can be freed although aview may attempt to access it.
>
>In particular code like this will crash:
>
>buf = numarray.asarray( array_struct_factory() ) # buffer is freed
>buf[1] = 2 # attempt is made to write to the non-existant buffer,
>causing a segfault
>
>I've "fixed" this issue with the following, which I'm sure is not the
>right way, but it's all I can do at this point.
>
>diff -u -r1.130 numarraycore.py
>--- Lib/numarraycore.py 4 Nov 2005 20:27:11 -0000       1.130
>+++ Lib/numarraycore.py 17 Nov 2005 11:38:29 -0000
>@@ -357,6 +357,7 @@
>         a = None
>         if hasattr(sequence, "__array_struct__"):
>             a =
>_numarray._array_from_array_struct(sequence.__array_struct__)
>+            a._hack_to_hold_reference_ = sequence.__array_struct__
>         elif (hasattr(sequence, "__array_shape__") and
>             hasattr(sequence, "__array_typestr__")):
>             typestr = sequence.__array_typestr__
>
>
>And while I'm at it, can the "from distutils.command.config import log"
>be turned off in setup.py? I like to see those errors, warnings, and
>status strings whiz past...
>
>
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