R devel - Apr 2022 - calloc() vs. R_Calloc()

On Thu, 7 Apr 2022 at 10:32, Tomas Kalibera <tomas.kalibera at gmail.com>
wrote:
>
> [...]
>
> And what are the errors you run into? On which platforms, under what
> circumstances, etc? It would be much easier to give advice knowing that.
>
> In principle, one issue you may run into when switching allocators is
> that you accidentally end up freeing by a different allocator from the
> one used to allocate it. It is common on Windows but can in principle
> happen elsewhere as well.
>
> Also by a slightly different heap layout or different allocator
> implementation you may wake up bugs in the program not seen previously
> (use after free, invalid memory accesses, etc)
>
That is something I do not know yet, since the only information the server
gives is this:
https://builder.r-hub.io/status/original/QCA_3.16.tar.gz-a03b4462b41df37c6284be1d5519e8b3

I'll probably end up debugging the C code, but since the only difference is
using Free() vs free() on exactly the same objects, I suspected a mis-usage
of the R commands.

The same setup passes with no problems on my local MacOS, but the errors
still seem to occur on the Windows setup from r-hub.

Best wishes,
Adrian

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On 4/7/22 10:32, Adrian Du?a wrote:
> On Thu, 7 Apr 2022 at 10:32, Tomas Kalibera <tomas.kalibera at
gmail.com>
> wrote:
>
>
>     [...]
>
>     And what are the errors you run into? On which platforms, under what
>     circumstances, etc? It would be much easier to give advice knowing
>     that.
>
>     In principle, one issue you may run into when switching allocators is
>     that you accidentally end up freeing by a different allocator from
>     the
>     one used to allocate it. It is common on Windows but can in principle
>     happen elsewhere as well.
>
>     Also by a slightly different heap layout or different allocator
>     implementation you may wake up bugs in the program not seen
>     previously
>     (use after free, invalid memory accesses, etc)
>
>
> That is something I do not know yet, since the only information the 
> server gives is this:
>
https://builder.r-hub.io/status/original/QCA_3.16.tar.gz-a03b4462b41df37c6284be1d5519e8b3
>
> I'll probably end up debugging the C code, but since the only 
> difference is using Free() vs free() on exactly the same objects, I 
> suspected a mis-usage of the R commands.
>
> The same setup passes with no problems on my local MacOS, but the 
> errors still seem to occur on the Windows setup from r-hub.
This is very likely because you are freeing memory allocated by calloc() 
(or something else but not R_Calloc() in your program) using R_Free() or 
memory allocated using R_Calloc() by using free() in your program.
I would recommend checking the source code manually for that.

It is not surprising that the problem doesn't appear on other platforms 
where the allocators happen to be the same.

Best
Tomas

>
> Best wishes,
> Adrian
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