Re: [V4l2-library] Announcing libv4l 0.3.1 aka "the vlc release"

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.

Cheers, Gregor

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