Crash on Windows with core.stdc.stdlib.free()

[Chris via Digitalmars-d-learn]

On Wednesday, 12 November 2014 at 16:10:34 UTC, ketmar via 
Digitalmars-d-learn wrote:
> On Wed, 12 Nov 2014 16:03:08 +0000
> Chris via Digitalmars-d-learn 
> <digitalmars-d-learn at puremagic.com> wrote:
>
>> On Wednesday, 12 November 2014 at 14:42:34 UTC, Chris wrote:
>> > On Wednesday, 12 November 2014 at 14:26:15 UTC, ketmar via
>> >> if you can extend C DLL, just add wrapper for `free()` 
>> >> there. so you
>> >> will not call `free()` from D, but call C DLL function 
>> >> which will free
>> >> the memory. it's a good practice anyway, 'cause it's 
>> >> recommended to
>> >> free memory in the same library where you allocated it.
>> >
>> > I initially had an implementation that did exactly that (I 
>> > usually do that), but for some reason it didn't work 
>> > properly in this particular case and caused all sorts of 
>> > undefined behavior. But I'll have a look at it again.
>> 
>> I've changed the code so that the memory is freed in C. 
>> Although it works "better" it crashes too every now and then
>> 
>> (WindowsError : exception : access violation writing 
>> 0x0310A1B4)
>> 
>> Will look into it.
> this also can happen due to allocators conflict somehow. or due 
> to
> other code which stores the pointer somewhere and then accesses 
> the
> memory. i think that it will be hard to trace without debugger.

Thanks a million! Just checked it this morning. It was the 
latter. I kept a reference to short* data in a class variable in 
D and didn't clear that reference when freeing the memory in the 
C library.

Interesting though that it never crashes on Linux, only on 
Windows did this cause problems.

It is also interesting that core.stdc.stdlib.free() and free() in 
the C library produced a slightly different crash behavior. But 
that might be down to the fact that the two happen in different 
places in the program.