Re: [Ironpython-users] Memory Allocation in Iron Python

2012-01-23 Thread Jeff Hardy 
There are a couple of known bugs in ctypes. Can you produce a
self-contained example, perhaps using a libc on Windows API function
as the target?

- Jeff

On Sun, Jan 22, 2012 at 3:50 PM, Jim Pattee  wrote:
> I am trying to allocate memory in Iron Python to receive text from a DLL.
> The allocated memory address is passed to the DLL and the text is copied by
> the DLL into the memory area. The following code, which works in CPython, is
> used:
>
> allocated = []
>
> def MemoryAllocation(size):
>
>   arr_type = c_char * size    # create a c_char array
>
>   arr_obj = arr_type()    # create an array object
>
>   allocated.append(arr_obj)   # so the object will not be destroyed
>
>   if len(allocated) > 1:  # free memory for the previous object
>
>     del allocated[0]
>
>   return addressof(arr_obj)   # return a pointer
>
>
>
> When this is used for Iron Python it results in:
>
> “Unhandled Exception: System.AccessViolationException: Attempted to read or
> write
>
>  protected memory. This is often an indication that other memory is
> corrupt.”
>
>
>
> The error results when the memory is copied into Python by the DLL. There
> are no errors displayed when executing the above code.
>
>
>
> Why can it not write to the memory? What is the difference in Iron Python
> and CPython?
>
>
>
>
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>
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Re: [Ironpython-users] Memory Allocation in Iron Python

2012-01-23 Thread Dino Viehland 
One potential issue here could be ASCII vs Unicode strings.  Depending on 
wherever the copy into this memory occurs it could end up copying the Unicode 
string into a buffer which is sized for ASCII strings.

From: [email protected] 
[mailto:[email protected]] On Behalf Of 
Markus Schaber
Sent: Sunday, January 22, 2012 11:44 PM
To: Jim Pattee; [email protected]
Subject: Re: [Ironpython-users] Memory Allocation in Iron Python

Hi, Jim,

You only gave us half of the source. Which way do you pass the memory address 
to the native DLL?

One difference is, for example, that .NET relocates objects sometimes, so they 
need to be pinned.

Best regards

Markus Schaber
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Von: 
[email protected]
 
[mailto:[email protected]]
 Im Auftrag von Jim Pattee
Gesendet: Montag, 23. Januar 2012 00:50
An: [email protected]
Betreff: [Ironpython-users] Memory Allocation in Iron Python

I am trying to allocate memory in Iron Python to receive text from a DLL. The 
allocated memory address is passed to the DLL and the text is copied by the DLL 
into the memory area. The following code, which works in CPython, is used:
allocated = []
def MemoryAllocation(size):
 arr_type = c_char * size# create a c_char array
 arr_obj = arr_type()# create an array object
 allocated.append(arr_obj)   # so the object will not be destroyed
 if len(allocated) > 1:  # free memory for the previous object
  del allocated[0]
 return addressof(arr_obj)   # return a pointer

When this is used for Iron Python it results in:
“Unhandled Exception: System.AccessViolationException: Attempted to read or 
write
protected memory. This is often an indication that other memory is corrupt.”

The error results when the memory is copied into Python by the DLL. There are 
no errors displayed when executing the above code.

Why can it not write to the memory? What is the difference in Iron Python and 
CPython?

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