[libvirt] [PATCH python] Protect against user accidentally calling constructors directly

[Michal Privoznik]

On 01/19/2017 04:20 PM, Daniel P. Berrange wrote:
> When using libvirt python you must never call the object
> constructors directly, as these are expecting to be passed
> a wrapped C object. For example
> 
>    import libvirt
>    c = libvirt.virConnect("qemu:///system")
>    c.listAllDomains()
> 
> will mysteriously segfault. With this change the user now
> gets an slightly more helpful error
> 
>   Traceback (most recent call last):
>     File "<stdin>", line 1, in <module>
>     File "/home/berrange/src/virt/libvirt-python/build/libvirt.py", line 3409, in __init__
>       raise Exception("Expected a wrapped C Object but got %s" % type(_obj))
>   Exception: Expected a wrapped C Object but got <type 'str'>
> 
> Signed-off-by: Daniel P. Berrange <berrange at redhat.com>
> ---
>  generator.py | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/generator.py b/generator.py
> index e9be8b1..6bcf80b 100755
> --- a/generator.py
> +++ b/generator.py
> @@ -1532,6 +1532,8 @@ def buildWrappers(module):
>                  elif classname in [ "virDomainSnapshot" ]:
>                      classes.write("        self._dom = dom\n")
>                      classes.write("        self._conn = dom.connect()\n")
> +                classes.write("        if type(_obj).__name__ not in [\"PyCapsule\", \"PyCObject\"]:\n")
> +                classes.write("            raise Exception(\"Expected a wrapped C Object but got %s\" % type(_obj))\n")
>                  classes.write("        self._o = _obj\n\n")
>              destruct=None
>              if classname in classes_destructors:
> 

ACK

Michal