On Thu, 12 Jan 2012, Huajun Li wrote:
> >> + � � index = id - usb_storage_usb_ids;
> >> + � � size = sizeof(us_unusual_dev_list) / sizeof(struct us_unusual_dev);
> >> + � � if (index < 0 || index >= size - 1) {
> >
> > No, no! �This is totally bogus. �According to the C language
> > specification, if id doesn't point to a member of the
> > usb_storage_usb_ids array then the difference id - usb_storage_usb_ids
> > is meaningless. �You can't depend on it having any particular value at
> > all.
> >
> > The right way to do the test is like this:
> >
> > � � � �size = ARRAY_SIZE(us_unusual_dev_list);
> > � � � �if (id < usb_storage_usb_ids || id >= usb_storage_usb_ids + size) {
> >
>
> Will change it although it could work per my test.
>
> However, there is a terminating entry in usb_storage_usb_ids, so
> maybe it should be changed to below one, right ?
> if (id < usb_storage_usb_ids || id >= usb_storage_usb_ids + size - 1) {
This doesn't matter. The terminating entry is empty, so id will never
point to it.
Alan Stern
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