Re: [Valgrind-users] improbably "uninitialized value" warning

[Daniel M. \(IMI\) <da...@im...>]

----- Original Message ----- 
From: "Tom Hughes" <th...@cy...>
To: <rj...@du...>; <da...@im...>
Cc: <val...@li...>
Sent: Tuesday, September 28, 2004 11:24
Subject: Re: [Valgrind-users] improbably "uninitialized value" warning


> In message <014101c4a581$a0840f70$0401a8c0@dan>
>           "Daniel Miller \(IMI\)" <da...@im...> wrote:
>
> > static int get_number_of_luns(usb_dev_handle *udev)
> > {
> >    char xbuf ;
> >    //  swap bytes around because u16 fields in
> >    //  usb_control_msg() are big-endian
> >    int result = usb_control_msg(udev, //  handle
> >             0xA1,    //  requesttype
> >             0xFE,    //  request
> >             0,       //  value
> >             0,       //  index
> >             &xbuf,   //  data pointer
> >             1,       //  length
> >             5000) ;  //  timeout
> >    if (result < 0)
> >       return result;
> >    result = (int) (xbuf) + 1 ;
> >    return result;
> > }
> >
> > The A1/FE control message returns one byte.  So it doesn't look, to me,
as
> > though get_number_of_luns() can fail to return a value...
>
> But where does use_control_msg get the value of xbuf from?
>
> Given that this is obviously originating from a USB device it
> is possible that there is some ioctl involved that valgrind
> doesn't understand - do you get any warnings about ioctls?
>
> Tom

Yeah, I get three of the following; I'm still trying to figure out what
0x4B30 is and what to do about them...

==29190== Warning: noted but unhandled ioctl 0x4B30 with no size/direction
hints
==29190==    This could cause spurious value errors to appear.
==29190==    See README_MISSING_SYSCALL_OR_IOCTL for guidance on writing a
proper wrapper.

However, the usb_control_msg ioctl is 0x5530, not 0x4B30.  In any case, if
usb_control_msg fails to get its data, it typically returns -1, and I don't
use xbuf in that case, which is what I was referring to previously...

    Dan