Re: Announcing libv4l 0.3.1 aka "the vlc release"

[Hans de Goede <j.w.r.degoede@hhs.nl>]

Gregor Jasny wrote:
> Hi,
> 
> I've just included libv4l2 in our app. After after a short debugging
> session I noticed the following:
> 
> In the man page the ioctl prototype is defined as
> int ioctl(int d, int request, ...). To catch the EINTR case I wrote a
> wrapper function:
> 
> int xioctl (int fd, int request, void *arg)
> 
> But as long as the request argument is int instead of unsigned long, the
> request gets sign extended:
> 
> xioctl (fd, VIDIOC_TRY_FMT, &fmt)
> (gdb) p/x request
> $2 = 0xc0d05640
> 
> int v4l2_ioctl (int fd, unsigned long int request, ...);
> (gdb) p/x request
> $3 = 0xffffffffc0d05640
> 
> Maybe you should mention this "issue" in the FAQ or documentaion.
> 

Thanks for reporting this, this has saved me quite some time while debugging 
issues with xawtv and kopete. I believe that the upper 32 bits added by this 
(obviously wrong code) get thrown away somewhere down the path to the kernel on 
64 bit archs, so I've modified libv4l to just ignore the upper 32 bits to match 
this behavior.

Regards,

Hans

> PS: Should I submit the sar-constraint patch to Thierry myself?

Nope I was just being slow, just like with answering this. Thanks for the 
testing and the patches!

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