Re: [Patch] Moving v4l1 ioctls from kernel to libv4l1

[Hans de Goede <hdegoede@redhat.com>]

Hi,

Looks good. I've committed this to my tree (I did some coding style
cleanups and added the permission mails received so far for re-using
the kernel code in the LGPL libv4l1), see:
http://git.linuxtv.org/v4l-utils.git?a=commitdiff;h=80e71ff2881617be317301a30d85a9b7f038aaca

Some requests for future patches:
1) please use git send-email for sending patches, including revisions
of patches. your mail clients mangles patches
("-" at the beginning of a line becomes "- -", line wraps them too).

2) please run checkpatch.pl from the kernel tree on your patches
before sending them, in the v4l-utils dir do:
git format-patch HEAD~
Then cd into a directory with extracted linux kernel source and do:
scripts/checkpatch.pl <path>/v4l-utils/0001-<patch-name>.patch

And fix any warnings and errors.

Thanks & Regards,

Hans





On 05/19/2010 10:43 AM, Huzaifa Sidhpurwala wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Thanks a lot for the review, here is the improved version.
>
>
> diff --git a/lib/libv4l1/libv4l1.c b/lib/libv4l1/libv4l1.c
> index eae3b43..9ef9980 100644
> - --- a/lib/libv4l1/libv4l1.c
> +++ b/lib/libv4l1/libv4l1.c
> @@ -61,6 +61,10 @@
>   #define V4L1_PIX_FMT_TOUCHED    0x04
>   #define V4L1_PIX_SIZE_TOUCHED   0x08
>
> +#ifndef min
> +    #define min( a, b ) ( ((a)<  (b)) ? (a) : (b) )
> +#endif
> +
>   static pthread_mutex_t v4l1_open_mutex = PTHREAD_MUTEX_INITIALIZER;
>   static struct v4l1_dev_info devices[V4L1_MAX_DEVICES] = {
>   	{ .fd = -1 },
> @@ -130,6 +134,19 @@ static unsigned int pixelformat_to_palette(unsigned
> int pixelformat)
>   	return 0;
>   }
>
> +static int count_inputs(int fd)
> +{
> +	struct v4l2_input input2;
> +	int i;
> +	for (i = 0;; i++) {
> +		memset(&input2, 0, sizeof(input2));
> +		input2.index = i;
> +		if (0 != SYS_IOCTL(fd, VIDIOC_ENUMINPUT,&input2))
> +			break;
> +		}
> +	return i;
> +}
> +
>   static int v4l1_set_format(int index, unsigned int width,
>   		unsigned int height, int v4l1_pal, int width_height_may_differ)
>   {
> @@ -491,16 +508,46 @@ int v4l1_ioctl(int fd, unsigned long int request, ...)
>   	switch (request) {
>   	case VIDIOCGCAP: {
>   		struct video_capability *cap = arg;
> +		
> +		struct v4l2_framebuffer fbuf = { 0, };
> +		struct v4l2_capability cap2 =  { 0, };
>
> - -		result = SYS_IOCTL(fd, request, arg);
> +		result = SYS_IOCTL(fd, VIDIOC_QUERYCAP,&cap2);
> +		if (result<  0)
> +			break;
> +
> +		if (cap2.capabilities&  V4L2_CAP_VIDEO_OVERLAY) {
> +			result = SYS_IOCTL(fd, VIDIOC_G_FBUF,&fbuf);
> +			if (result<  0) {
> +				memset(&fbuf, 0, sizeof(fbuf));
> +			}
> +			result = 0;
> +		}
> +		
> +		memcpy(cap->name,  cap2.card, min(sizeof(cap->name),sizeof(cap2.card)) );
> +		
> +		cap->name[sizeof(cap->name) -1 ] = 0;
> +	
> +		if (cap2.capabilities&  V4L2_CAP_VIDEO_CAPTURE)
> +			cap->type |= VID_TYPE_CAPTURE;
> +		if (cap2.capabilities&  V4L2_CAP_TUNER)
> +			cap->type |= VID_TYPE_TUNER;
> +		if (cap2.capabilities&  V4L2_CAP_VBI_CAPTURE)
> +			cap->type |= VID_TYPE_TELETEXT;
> +		if (cap2.capabilities&  V4L2_CAP_VIDEO_OVERLAY)
> +			cap->type |= VID_TYPE_OVERLAY;
> +		if (fbuf.capability&  V4L2_FBUF_CAP_LIST_CLIPPING)
> +			cap->type |= VID_TYPE_CLIPPING;
> +
> +		cap->channels = count_inputs(fd);
>
> - -		/* override kernel v4l1 compat min / max size with our own more
> - -		   accurate values */
>   		cap->minwidth  = devices[index].min_width;
>   		cap->minheight = devices[index].min_height;
>   		cap->maxwidth  = devices[index].max_width;
>   		cap->maxheight = devices[index].max_height;
> +
>   		break;
> +
>   	}
>
>   	case VIDIOCSPICT: {
>
>
>
>
> Hans de Goede wrote:
>> Hi Huzaifa,
>>
>> First of all many thanks for working on this!
>>
>> Comments inline.
>>
>> On 05/18/2010 01:12 PM, Huzaifa Sidhpurwala wrote:
>>> Hi All,
>>> I have been working with Hans for moving the v4l1 ioctls from the kernel
>>> to libv4l1.
>>> It would be best to work on one ioctl at a time.
>>> The enclosed patch attempts to implement VIDIOCGCAP in the libv4l1.
>>>
>>> Note: Hans is working with Bill, asking for permission to re-use the
>>> v4l1-compat.c code under the LGPL
>>>
>>>
>>>
>>> diff --git a/lib/libv4l1/libv4l1.c b/lib/libv4l1/libv4l1.c
>>> index eae3b43..8571651 100644
>>> --- a/lib/libv4l1/libv4l1.c
>>> +++ b/lib/libv4l1/libv4l1.c
>>> @@ -61,6 +61,10 @@
>>>    #define V4L1_PIX_FMT_TOUCHED    0x04
>>>    #define V4L1_PIX_SIZE_TOUCHED   0x08
>>>
>>> +#ifndef min
>>> +    #define min( a, b ) ( ((a)<   (b)) ? (a) : (b) )
>>> +#endif
>>> +
>>>    static pthread_mutex_t v4l1_open_mutex = PTHREAD_MUTEX_INITIALIZER;
>>>    static struct v4l1_dev_info devices[V4L1_MAX_DEVICES] = {
>>>        { .fd = -1 },
>>> @@ -130,6 +134,45 @@ static unsigned int pixelformat_to_palette(unsigned
>>> int pixelformat)
>>>        return 0;
>>>    }
>>>
>>> +static int count_inputs(int fd)
>>> +{
>>> +    struct v4l2_input input2;
>>> +    int i;
>>> +    for (i = 0;; i++) {
>>> +        memset(&input2, 0, sizeof(input2));
>>> +        input2.index = i;
>>> +        if (0 != SYS_IOCTL(fd, VIDIOC_ENUMINPUT,&input2))
>>> +            break;
>>> +        }
>>> +    return i;
>>> +}
>>> +
>>> +static int check_size(int fd,int *maxw,int *maxh)
>>> +{
>>> +    struct v4l2_fmtdesc desc2;
>>> +    struct v4l2_format fmt2;
>>> +
>>> +    memset(&desc2, 0, sizeof(desc2));
>>> +    memset(&fmt2, 0, sizeof(fmt2));
>>> +
>>> +    desc2.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
>>> +    if (0 != SYS_IOCTL(fd, VIDIOC_ENUM_FMT,&desc2))
>>> +        goto done;
>>> +
>>> +    fmt2.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
>>> +    fmt2.fmt.pix.width = 10000;
>>> +    fmt2.fmt.pix.height = 10000;
>>> +    fmt2.fmt.pix.pixelformat = desc2.pixelformat;
>>> +    if (0 != SYS_IOCTL(fd, VIDIOC_TRY_FMT,&fmt2))
>>> +        goto done;
>>> +
>>> +    *maxw = fmt2.fmt.pix.width;
>>> +    *maxh = fmt2.fmt.pix.height;
>>> +
>>> +    done:
>>> +    return 0;
>>> +}
>>> +
>>
>> We don't need this function, see below.
>>
>>>    static int v4l1_set_format(int index, unsigned int width,
>>>            unsigned int height, int v4l1_pal, int width_height_may_differ)
>>>    {
>>> @@ -492,7 +535,54 @@ int v4l1_ioctl(int fd, unsigned long int request,
>>> ...)
>>>        case VIDIOCGCAP: {
>>>            struct video_capability *cap = arg;
>>>
>>> -        result = SYS_IOCTL(fd, request, arg);
>>> +        long err;
>>> +        struct v4l2_framebuffer fbuf;
>>> +        struct v4l2_capability *cap2;
>>
>> The kernel mallocs struct v4l2_capability because the kernel
>> stack is severely limited, no need to do that in userspace, just
>> put the entire struct on the stack.
>>
>>> +
>>> +        cap2 = malloc (sizeof(*cap2));
>>> +        if (!cap2) {
>>> +            return -ENOMEM;
>>> +        }
>>> +
>>> +        memset(cap,0,sizeof(*cap));
>>> +        memset(&fbuf, 0, sizeof(fbuf));
>>> +
>>
>> You can get the memset effect, by initalizing the first field of the
>> struct to 0, the compiler will then 0 out the rest:
>>          struct v4l2_framebuffer fbuf = { 0, };
>>          struct v4l2_capability cap2 =  { 0, };
>>
>>
>>> +        err = SYS_IOCTL(fd, VIDIOC_QUERYCAP,cap2);
>>> +        if (err<   0)
>>> +            goto done;
>>> +
>>> +        if (cap2->capabilities&   V4L2_CAP_VIDEO_OVERLAY) {
>>> +            err = SYS_IOCTL(fd, VIDIOC_G_FBUF,&fbuf);
>>> +            if (err<   0) {
>>> +                memset(&fbuf, 0, sizeof(fbuf));
>>> +            }
>>> +            err = 0;
>>> +        }
>>> +
>>> +        memcpy(cap->name,  cap2->card,
>>> min(sizeof(cap->name),sizeof(cap2->card)) );
>>> +
>>> +        cap->name[sizeof(cap->name) -1 ] = 0;
>>> +
>>> +        if (cap2->capabilities&   V4L2_CAP_VIDEO_CAPTURE)
>>> +            cap->type |= VID_TYPE_CAPTURE;
>>> +        if (cap2->capabilities&   V4L2_CAP_TUNER)
>>> +            cap->type |= VID_TYPE_TUNER;
>>> +        if (cap2->capabilities&   V4L2_CAP_VBI_CAPTURE)
>>> +            cap->type |= VID_TYPE_TELETEXT;
>>> +        if (cap2->capabilities&   V4L2_CAP_VIDEO_OVERLAY)
>>> +            cap->type |= VID_TYPE_OVERLAY;
>>> +        if (fbuf.capability&   V4L2_FBUF_CAP_LIST_CLIPPING)
>>> +            cap->type |= VID_TYPE_CLIPPING;
>>> +
>>> +        cap->channels = count_inputs(fd);
>>> +
>>> +        check_size(fd,
>>> +&cap->maxwidth,&cap->maxheight);
>>> +
>>
>> No need to check size here, as we override that below, so this line can
>> be dropped.
>>
>>> +
>>> +    /*    result = SYS_IOCTL(fd, request, arg);*/
>>> +
>>
>> This can be dropped too.
>>
>>> +
>>>
>>>            /* override kernel v4l1 compat min / max size with our own more
>>>               accurate values */
>>
>> And the override comment can be dropped to, as we no longer will be
>> suing the v4l1 compat code check_size stuff.
>>
>>> @@ -500,7 +590,10 @@ int v4l1_ioctl(int fd, unsigned long int request,
>>> ...)
>>>            cap->minheight = devices[index].min_height;
>>>            cap->maxwidth  = devices[index].max_width;
>>>            cap->maxheight = devices[index].max_height;
>>> -        break;
>>> +
>>> +        done:
>>> +            free(cap2);
>>> +            break;
>>>        }
>>
>> No need to do this either when we drop the malloc.
>>
>>>
>>>        case VIDIOCSPICT: {
>>>
>>
>> Thanks&  Regards,
>>
>> Hans
>
>
> - --
> Regards,
> Huzaifa Sidhpurwala, RHCE, CCNA (IRC: huzaifas)
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