About the memset.
Let's say that there are two references to the memory. The memory is
released, but the other reference tries to access it. If memory is set to 0
before released, the second reference will still point to the same area,
don't it? I think it is useful even when not in debug. Remember that we
provide pre-compiled binaries without debug information. But the idea of
using a different value, like 0xDD, could be interesting. Why not 0xFF? In
a rare case this could point to a valid memory... (?)
We don't do that very often, only in a few parts of the IUP code that I
consider sensible for memory allocation.
Best,
Scuri
2017-12-13 13:35 GMT-02:00 Antonio Scuri <[email protected]>:
> That makes sense when they are not local variables, or when the function
> goes on with more code after the free. At the end of the function (or just
> before a return) to set the local pointer to NULL seems useless.
>
> Best,
> Scuri
>
> 2017-12-12 20:44 GMT-02:00 sur-behoffski <[email protected]>:
>
>> G'day again,
>>
>> Thank you for your responses to the three build summaries I sent out
>> yesterday. I've updated my Subversion repositories.
>>
>> Attached is a patch for im/trunk/src/process/im_analyze.cpp, which
>> gets rid of some of the remaining "misleading indentation" warnings.
>>
>> The comments in the patch, as well as the paranoid "set freed
>> stack-based pointers to NULL", are somewhat jarring relative to the
>> general tone and flow of the overall code of the module. I would
>> expect that some, or perhaps most, of these comments and paranoid code
>> would not be included in the immediate future; however, they may be
>> considered at some point. I'm using some level of paranoia in my
>> personal code, because I am striving to stay very clean in using and
>> freeing memory slabs and all associated memory pointers, so that it is
>> clean when run under Valgrind.
>>
>> Although I've tackled a significant slab of code, there are more
>> opportunities for this kind of rewrite in a few places, perhaps
>> mostly further down in the same function; e.g. (line numbers are
>> rough figures since they assume the attached patch has been applied):
>>
>> - Lines 834-844;
>> - Lines 963-974;
>>
>> And a couple of places where we can rely on free(3) to quietly
>> ignore NULL pointers:
>>
>> - Lines 707-708 ("if (local_data_cx) free(local_data_cx);");
>> - Line 1113 ("if (holes_perim) free(holes_perim);").
>>
>> cheers,
>>
>> sur-behoffski
>> programmer, Grouse Software
>>
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