VirtualBox

Ticket #19740 (closed defect: fixed)

Opened 2 years ago

Last modified 5 months ago

UnicodeDecodeError on takeScreenShotToArray with python 3

Reported by: gim Owned by:
Component: other Version: VirtualBox 6.1.10
Keywords: Cc:
Guest type: other Host type: other

Description

We have an exception on call display.takeScreenShotToArray with python 3

>>> data = display.takeScreenShotToArray(0, w, h, vboxMgr.constants.BitmapFormat_PNG)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "<XPCOMObject method 'takeScreenShotToArray'>", line 3, in takeScreenShotToArray
UnicodeDecodeError: 'utf-8' codec can't decode byte 0x89 in position 0: invalid start byte

Due to XIDL description it is returning octet array:

    <method name="takeScreenShotToArray">
      <desc>
        Takes a guest screen shot of the requested size and format
        and returns it as an array of bytes.
      </desc>
      <param name="screenId" type="unsigned long" dir="in">
        <desc>
          The guest monitor to take screenshot from.
        </desc>
      </param>
      <param name="width" type="unsigned long" dir="in">
        <desc>
          Desired image width.
        </desc>
      </param>
      <param name="height" type="unsigned long" dir="in">
        <desc>
          Desired image height.
        </desc>
      </param>
      <param name="bitmapFormat" type="BitmapFormat" dir="in">
        <desc>
          The requested format.
        </desc>
      </param>
      <param name="screenData" type="octet" dir="return" safearray="yes">
        <desc>
          Array with resulting screen data.
        </desc>
      </param>
    </method>

In python 3 it must be bytes array not an unicode string. So here is error, probably: https://www.virtualbox.org/browser/vbox/trunk/src/libs/xpcom18a4/python/src/VariantUtils.cpp#L620

if (array_type == nsXPTType::T_U8)
#if PY_MAJOR_VERSION <= 2
                return PyString_FromStringAndSize( (char *)array_ptr, sequence_size );
#else
                return PyUnicode_FromStringAndSize( (char *)array_ptr, sequence_size ); // <----- here is
#endif

So correct one when python 3:

return PyBytes_FromStringAndSize( (char *)array_ptr, sequence_size );

Change History

comment:1 Changed 2 years ago by gim

UP

This is really popular bug for python3 vboxapi users.

For example:  https://github.com/sethmlarson/virtualbox-python/issues/111 and here:  https://forums.virtualbox.org/viewtopic.php?f=34&t=98709

Still 5 weeks silence after specifying the exact location of this bug. Is VirtualBox developers alive!?

comment:2 Changed 5 months ago by galitsyn

  • Status changed from new to closed
  • Resolution set to fixed

Thank you for reporting the issue. It should be fixed in VirtualBox 6.1.36. Please refer to https://www.virtualbox.org/wiki/Downloads page.

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