From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from galahad.ideasonboard.com ([185.26.127.97]:34507 "EHLO galahad.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932757AbcAYUxi (ORCPT ); Mon, 25 Jan 2016 15:53:38 -0500 From: Laurent Pinchart To: Sakari Ailus Cc: Sakari Ailus , linux-media@vger.kernel.org, hverkuil@xs4all.nl Subject: Re: [v4l-utils PATCH 1/1] v4l: libv4l2subdev: Precisely convert media bus string to code Date: Mon, 25 Jan 2016 22:53:55 +0200 Message-ID: <2674749.G6RjQVDcz7@avalon> In-Reply-To: <20160125204707.GC14876@valkosipuli.retiisi.org.uk> References: <1449674087-19122-1-git-send-email-sakari.ailus@linux.intel.com> <1490379.zWhzdjB0Zz@avalon> <20160125204707.GC14876@valkosipuli.retiisi.org.uk> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-media-owner@vger.kernel.org List-ID: Hi Sakari, On Monday 25 January 2016 22:47:07 Sakari Ailus wrote: > On Mon, Jan 25, 2016 at 09:41:12PM +0200, Laurent Pinchart wrote: > > On Monday 25 January 2016 13:39:10 Sakari Ailus wrote: > > > On Sun, Dec 13, 2015 at 11:33:45PM +0200, Laurent Pinchart wrote: > > > > 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 > > > > > > Yes, that's the problem. > > > > > > > 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. > > > > > > I'll use this commit message then. > > > > > > >> Signed-off-by: Sakari Ailus > > > >> --- > > > >> This patch should be applied before the set "[v4l-utils PATCH v2 0/3] > > > >> List supported formats in libv4l2subdev": > > > >> > > > >> > > > >> > > > >> 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. > > > > > > Fine for me. > > > > > > > I also wonder whether we shouldn't just get rid of the length argument > > > > and force the passed format string to be zero-terminated. > > > > > > I believe the reason is that the current user (media-ctl test program) > > > parses the user input and passes a portion of that to this function to > > > convert the string to a numeric value. That'd be a bit more cumbersome > > > as we'd either require copying the string elsewhere or changing the > > > input by the program. I wouldn't change the behaviour, at least not now. > > > > Yes that's the reason, and I think it's an API design mistake (or just a > > lack of proper API design :-)). Wouldn't it be better to copy the string > > in the caller ? > > From the API point of view, I don't disagree. But I do think this should be > done in a separate patch, not in this one --- this is a bugfix, really. Sure, I agree with that. > I'll submit one more patch for that. Thank you. > > > >> + 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