Re: [PATCH] v4l2-compliance: fix function pointer prototype

[Hans Verkuil <hansverk@cisco.com>]

On 04/01/14 16:06, Prabhakar Lad wrote:
> Hi Hans,
> 
> On Tue, Apr 1, 2014 at 7:20 PM, Hans Verkuil <hansverk@cisco.com> wrote:
>> Hi Prabhakar,
>>
>> On 04/01/14 15:45, Lad, Prabhakar wrote:
>>> From: "Lad, Prabhakar" <prabhakar.csengg@gmail.com>
>>>
>>> There was a conflict between the mmap function pointer prototype of
>>> struct v4l_fd and the actual function used. Make sure it is in sync
>>> with the prototype of v4l2_mmap.
>>
>> The prototype of v4l2_mmap uses int64_t, so I don't understand this
>> patch.
>>
> Actual prototype of mmap is,
> 
>   void *mmap(void *addr, size_t length, int prot, int flags, int fd,
> off_t offset);
> 
> But where as the prototype in v4l_fd mmap the last parameter type is int64_t
> but that should have been off_t and same applies with test_mmap().

The problem is that v4l2_mmap (in lib/include/libv4l2.h) uses int64_t.
So the function pointer uses int64_t as well as does test_mmap.

I don't see how the current v4l-utils tree can cause a compile error.

For the record, I know you can't assign mmap to fd->mmap, you would
have to make a wrapper. Unfortunately mmap and v4l2_mmap do not have
the same prototype and I had to pick one (I'm not sure why they don't
use the same prototype).

Most applications would typically have to use v4l2_mmap, so I went with
that one.

Regards,

	Hans