Re: [v4l-utils PATCH 1/1] v4l: libv4l2subdev: Precisely convert media bus string to code

[Laurent Pinchart <laurent.pinchart@ideasonboard.com>]

Hi Sakari,

Thank you for the patch.

On Wednesday 09 December 2015 17:14:47 Sakari Ailus wrote:
> The length of the string was ignored, making it possible for the
> conversion to fail due to extra characters in the string.

I'm not sure to follow you there. Is the issue that passing a string such as 
"SBGGR10" would match "SBGGR10_DPCM8" if it was listed before "SBGGR10" ? If 
that's the case I'd write the commit message as

Any character beyond the fist `length' characters in the mbus_formats strings
are ignored, causing incorrect matches if the format entry starts with but 
isn't equal to the passed format.

> Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> ---
> This patch should be applied before the set "[v4l-utils PATCH v2 0/3] List
> supported formats in libv4l2subdev":
> 
> <URL:http://www.spinics.net/lists/linux-media/msg95377.html>
> 
>  utils/media-ctl/libv4l2subdev.c | 10 ++++------
>  1 file changed, 4 insertions(+), 6 deletions(-)
> 
> diff --git a/utils/media-ctl/libv4l2subdev.c
> b/utils/media-ctl/libv4l2subdev.c index 33c1ee6..cce527d 100644
> --- a/utils/media-ctl/libv4l2subdev.c
> +++ b/utils/media-ctl/libv4l2subdev.c
> @@ -769,14 +769,12 @@ enum v4l2_mbus_pixelcode
> v4l2_subdev_string_to_pixelcode(const char *string, unsigned int i;
> 
>  	for (i = 0; i < ARRAY_SIZE(mbus_formats); ++i) {
> -		if (strncmp(mbus_formats[i].name, string, length) == 0)
> -			break;
> +		if (strncmp(mbus_formats[i].name, string, length) == 0
> +		    && strlen(mbus_formats[i].name) == length)

How about mbus_formats[i].name[length] == '\0' instead ? That should be more 
efficient.

I also wonder whether we shouldn't just get rid of the length argument and 
force the passed format string to be zero-terminated.

> +			return mbus_formats[i].code;
>  	}
> 
> -	if (i == ARRAY_SIZE(mbus_formats))
> -		return (enum v4l2_mbus_pixelcode)-1;
> -
> -	return mbus_formats[i].code;
> +	return (enum v4l2_mbus_pixelcode)-1;
>  }
> 
>  static struct {

-- 
Regards,

Laurent Pinchart