From: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Date: Fri, 11 Feb 2011 17:54:51 +0000 (+0000)
Subject: qemu-xen: fix segfault with empty cdroms
X-Git-Tag: xen-4.1.0-rc5^0
X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=e073e69457b4d99b6da0b6536296e3498f7f6599;p=qemu-xen-4.1-testing.git

qemu-xen: fix segfault with empty cdroms

When the cdrom is empty the params node in xenstore might be missing
completely.  Cope with it instead of segfaulting.

Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
---

diff --git a/hw/xen_disk.c b/hw/xen_disk.c
index 218f65451..6aebb77ba 100644
--- a/hw/xen_disk.c
+++ b/hw/xen_disk.c
@@ -582,12 +582,13 @@ static int blk_init(struct XenDevice *xendev)
 {
     struct XenBlkDev *blkdev = container_of(xendev, struct XenBlkDev, xendev);
     int mode, 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, ':');
 	if (h != NULL) {
 	    blkdev->fileproto = blkdev->params;
 	    blkdev->filename  = h+1;