Re: [Qemu-devel] [PATCH 02/40] elf: Add notes implementation

[Alexander Graf]

On 01.11.2010, at 16:19, Stefan Weil wrote:

> Am 01.11.2010 20:51, schrieb Alexander Graf:
>> On 01.11.2010, at 14:42, Stefan Weil wrote:
>> 
>>   
>>> Am 01.11.2010 19:29, schrieb Blue Swirl:
>>>     
>>>> On Mon, Nov 1, 2010 at 3:01 PM, Alexander Graf<address@hidden>   wrote:
>>>> 
>>>>       
>>>>> ---
>>>>>  hw/elf_ops.h |   61 
>>>>> +++++++++++++++++++++++++++++++++++++++++++++++++++++++++-
>>>>>  hw/loader.c  |    7 ++++++
>>>>>  hw/loader.h  |    3 ++
>>>>>  3 files changed, 70 insertions(+), 1 deletions(-)
>>>>> 
>>>>> diff --git a/hw/elf_ops.h b/hw/elf_ops.h
>>>>> index 8b63dfc..645d058 100644
>>>>> --- a/hw/elf_ops.h
>>>>> +++ b/hw/elf_ops.h
>>>>> @@ -189,6 +189,44 @@ static int glue(load_symbols, SZ)(struct elfhdr 
>>>>> *ehdr, int fd, int must_swab,
>>>>>     return -1;
>>>>>  }
>>>>> 
>>>>> +static void glue(elf_read_notes, SZ)(uint8_t *data, int data_len,
>>>>> +                                     ElfHandlers *handlers, int 
>>>>> must_swab)
>>>>> +{
>>>>> +    uint8_t *p = data;
>>>>> +
>>>>> +    while ((ulong)&p[3]<   (ulong)&data[data_len]) {
>>>>> 
>>>>>         
>>>> Please use 'unsigned long'.
>>>> 
>>>>       
>>> Why is a type cast used here? I see no reason for it.
>>>     
>> Pointers can't be compared, you have to cast them to values first.
>> 
>> 
>> Alex
>>   
> 
> No. Pointers of same type which are not void pointers can be compared.
> 
> There is even a data type ptrdiff_t, so you can also compare their
> difference with zero.

Let's ask someone who definitely knows :).

Michael, is code like

char *x = a, *y = b;
if (x < y) {
  ...
}

valid? Or do I first have to cast x and y to unsigned longs or uintptr_t?


Alex