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

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
	[[alternative HTML version deleted]]

Hello,

Tomas is right, there are many memory operations allocating with malloc 
and freeing with R_Free:

line: variables - operation

  55: p_pichart - malloc
336: p_pichart - R_Free

236: copy_implicants - malloc
260: copy_implicants - R_Free

240: p_tempic - malloc
262: p_tempic - R_Free


And there are more cases like these. For what I've seen, the frequent 
(unique?) case is malloc/R_Free.

Hope this helps,

Rui Barradas

?s 09:59 de 07/04/2022, Tomas Kalibera escreveu:
> 
> 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
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel