Am 11.02.2011 13:38, schrieb Stefano Stabellini:
> When disk is a cdrom and the drive is empty the "params" node in
> xenstore might be missing completely: cope with it instead of
> segfaulting.
>
> Signed-off-by: Stefano Stabellini <stefano.stabell...@eu.citrix.com>
>
>
> diff --git a/hw/xen_disk.c b/hw/xen_disk.c
> index 134ac33..e553c4c 100644
> --- a/hw/xen_disk.c
> +++ b/hw/xen_disk.c
> @@ -577,12 +577,13 @@ static int blk_init(struct XenDevice *xendev)
> {
> struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev,
> xendev);
> int index, qflags, have_barriers, info = 0;
> - char *h;
> + char *h = NULL;
>
> /* read xenstore entries */
> if (blkdev->params == NULL) {
> blkdev->params = xenstore_read_be_str(&blkdev->xendev, "params");
> - h = strchr(blkdev->params, ':');
> + if (blkdev->params != NULL)
> + h = strchr(blkdev->params, ':');
The coding style requires braces here.
> if (h != NULL) {
> blkdev->fileproto = blkdev->params;
> blkdev->filename = h+1;
Let me add some more context:
if (h != NULL) {
blkdev->fileproto = blkdev->params;
blkdev->filename = h+1;
*h = 0;
} else {
blkdev->fileproto = "<unset>";
blkdev->filename = blkdev->params;
}
So in the NULL case we now have blkdev->filename = NULL. Doesn't this
just move the crash a few lines downwards when bdrv_open() tries to use
NULL as its filename?
Kevin
