[PATCH] v4l2-compliance: fix function pointer prototype

[PATCH] v4l2-compliance: fix function pointer prototype

[Lad, Prabhakar]

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.

This patch fixes following build error,

v4l2-compliance.cpp: In function 'void v4l_fd_test_init(v4l_fd*, int)':
v4l2-compliance.cpp:132: error: invalid conversion from
'void* (*)(void*, size_t, int, int, int, int64_t)' to
'void* (*)(void*, size_t, int, int, int, off_t)'

Cc: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
---
 utils/v4l2-compliance/v4l-helpers.h     |    2 +-
 utils/v4l2-compliance/v4l2-compliance.h |    2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/utils/v4l2-compliance/v4l-helpers.h b/utils/v4l2-compliance/v4l-helpers.h
index 48ea602..b2ce6c0 100644
--- a/utils/v4l2-compliance/v4l-helpers.h
+++ b/utils/v4l2-compliance/v4l-helpers.h
@@ -10,7 +10,7 @@ struct v4l_fd {
 	int fd;
 	int (*ioctl)(int fd, unsigned long cmd, ...);
 	void *(*mmap)(void *addr, size_t length, int prot, int flags,
-		      int fd, int64_t offset);
+		      int fd, off_t offset);
 	int (*munmap)(void *addr, size_t length);
 };
 
diff --git a/utils/v4l2-compliance/v4l2-compliance.h b/utils/v4l2-compliance/v4l2-compliance.h
index f2f7072..b6d4dae 100644
--- a/utils/v4l2-compliance/v4l2-compliance.h
+++ b/utils/v4l2-compliance/v4l2-compliance.h
@@ -137,7 +137,7 @@ static inline int test_ioctl(int fd, unsigned long cmd, ...)
 }
 
 static inline void *test_mmap(void *start, size_t length, int prot, int flags,
-		int fd, int64_t offset)
+		int fd, off_t offset)
 {
  	return wrapper ? v4l2_mmap(start, length, prot, flags, fd, offset) :
 		mmap(start, length, prot, flags, fd, offset);
-- 
1.7.9.5

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

[Hans Verkuil]

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.

Regards,

	Hans

> 
> This patch fixes following build error,
> 
> v4l2-compliance.cpp: In function 'void v4l_fd_test_init(v4l_fd*, int)':
> v4l2-compliance.cpp:132: error: invalid conversion from
> 'void* (*)(void*, size_t, int, int, int, int64_t)' to
> 'void* (*)(void*, size_t, int, int, int, off_t)'
> 
> Cc: Hans Verkuil <hans.verkuil@cisco.com>
> Signed-off-by: Lad, Prabhakar <prabhakar.csengg@gmail.com>
> ---
>  utils/v4l2-compliance/v4l-helpers.h     |    2 +-
>  utils/v4l2-compliance/v4l2-compliance.h |    2 +-
>  2 files changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/utils/v4l2-compliance/v4l-helpers.h b/utils/v4l2-compliance/v4l-helpers.h
> index 48ea602..b2ce6c0 100644
> --- a/utils/v4l2-compliance/v4l-helpers.h
> +++ b/utils/v4l2-compliance/v4l-helpers.h
> @@ -10,7 +10,7 @@ struct v4l_fd {
>  	int fd;
>  	int (*ioctl)(int fd, unsigned long cmd, ...);
>  	void *(*mmap)(void *addr, size_t length, int prot, int flags,
> -		      int fd, int64_t offset);
> +		      int fd, off_t offset);
>  	int (*munmap)(void *addr, size_t length);
>  };
>  
> diff --git a/utils/v4l2-compliance/v4l2-compliance.h b/utils/v4l2-compliance/v4l2-compliance.h
> index f2f7072..b6d4dae 100644
> --- a/utils/v4l2-compliance/v4l2-compliance.h
> +++ b/utils/v4l2-compliance/v4l2-compliance.h
> @@ -137,7 +137,7 @@ static inline int test_ioctl(int fd, unsigned long cmd, ...)
>  }
>  
>  static inline void *test_mmap(void *start, size_t length, int prot, int flags,
> -		int fd, int64_t offset)
> +		int fd, off_t offset)
>  {
>   	return wrapper ? v4l2_mmap(start, length, prot, flags, fd, offset) :
>  		mmap(start, length, prot, flags, fd, offset);
> 

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

[Prabhakar Lad]

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().

Thanks,
--Prabhakar Lad

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

[Hans Verkuil]

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

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

[Hans Verkuil]

On 04/01/14 16:26, Hans Verkuil wrote:
> 
> 
> 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.
> 

I missed that mmap is assigned to v4l_fd_init(). Since mmap and v4l2_mmap
have different prototypes the only solution is to make a wrapper.

Does this work?

diff --git a/utils/v4l2-compliance/v4l-helpers.h b/utils/v4l2-compliance/v4l-helpers.h
index 48ea602..e718a24 100644
--- a/utils/v4l2-compliance/v4l-helpers.h
+++ b/utils/v4l2-compliance/v4l-helpers.h
@@ -14,11 +14,21 @@ struct v4l_fd {
 	int (*munmap)(void *addr, size_t length);
 };
 
+/*
+ * mmap has a different prototype compared to v4l2_mmap. Because of
+ * this we have to make a wrapper for it.
+ */
+static inline void *v4l_fd_mmap(void *addr, size_t length, int prot, int flags,
+		                      int fd, int64_t offset)
+{
+	return mmap(addr, length, prot, flags, fd, offset);
+}
+
 static inline void v4l_fd_init(struct v4l_fd *f, int fd)
 {
 	f->fd = fd;
 	f->ioctl = ioctl;
-	f->mmap = mmap;
+	f->mmap = v4l_fd_mmap;
 	f->munmap = munmap;
 }
 

On a 64-bit system the types are the same, it's only on a 32-bit system that
this will fail.

Regards,

	Hans

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

[Prabhakar Lad]

Hi Hans,

On Tue, Apr 1, 2014 at 8:12 PM, Hans Verkuil <hverkuil@xs4all.nl> wrote:
> On 04/01/14 16:26, Hans Verkuil wrote:
>>
>>
>> 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.
>>
>
> I missed that mmap is assigned to v4l_fd_init(). Since mmap and v4l2_mmap
> have different prototypes the only solution is to make a wrapper.
>
> Does this work?
>
Yes it compiles now with the below patch.

Thanks,
--Prabhakar Lad

> diff --git a/utils/v4l2-compliance/v4l-helpers.h b/utils/v4l2-compliance/v4l-helpers.h
> index 48ea602..e718a24 100644
> --- a/utils/v4l2-compliance/v4l-helpers.h
> +++ b/utils/v4l2-compliance/v4l-helpers.h
> @@ -14,11 +14,21 @@ struct v4l_fd {
>         int (*munmap)(void *addr, size_t length);
>  };
>
> +/*
> + * mmap has a different prototype compared to v4l2_mmap. Because of
> + * this we have to make a wrapper for it.
> + */
> +static inline void *v4l_fd_mmap(void *addr, size_t length, int prot, int flags,
> +                                     int fd, int64_t offset)
> +{
> +       return mmap(addr, length, prot, flags, fd, offset);
> +}
> +
>  static inline void v4l_fd_init(struct v4l_fd *f, int fd)
>  {
>         f->fd = fd;
>         f->ioctl = ioctl;
> -       f->mmap = mmap;
> +       f->mmap = v4l_fd_mmap;
>         f->munmap = munmap;
>  }
>
>
> On a 64-bit system the types are the same, it's only on a 32-bit system that
> this will fail.
>
> Regards,
>
>         Hans