[DVDnav-discuss] [PATCH] libdvdread: Fix crash when PTT is too short

[Miroslav Jezbera]

Dne 11.7.2011 05:40, Frédéric Marchal napsal(a):
> On Sunday 10 July 2011 11:38:11 Mirek Jezbera wrote:
>> Hi Dominik,
>>> I assume that sizeof(uint32_t) comes from a few lines above:
>>>
>>> data = (uint32_t *)malloc(info_length);
>>>
>>> Why not use sizeof(*data)?
>> Are you sure, that sizeof can determine size of memory allocated with
>> malloc? I think it can return size of statically allocated structures and
>> base types.
> Just to keep track of the answer: malloc cannot determine the size of a
> dynamically allocated object but that's not the purpose. sizeof(*data) returns
> the size of one item pointed by data. It could be written as sizeof(data[0]).
>
> It is computed at compile time and doesn't even require that data points to a
> valid memory. sizeof(*data) will work even if data is NULL or invalid.
>
> And for the record, sizeof(Data) is the size of a pointer. It is not the size
> of the allocated memory.
>
> Frederic
Hi Frederic,
thank you for your explanation. I have missed, that sizeof(*data) is 
replacement of sizeof(uint32_t). I have wrongly thought, that Dominic 
want to use sizeof to determine number of elements in data.

Jezz