lguest example launcher truncates block device file to 0 length on problems

The function should also use ftruncate64() rather than ftruncate() to prevent
files over 4GB (not uncommon for a root filesystem) being zeroed.

Signed-off-by: Chris Malley <mail@chrismalley.co.uk>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 1 insertions, 1 deletions

diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index f7918401a007..73c5f1f3d5d2 100644
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -882,7 +882,7 @@ static u32 handle_block_output(int fd, const struct iovec *iov,
                  * of the block file (possibly extending it). */
                 if (off + len > device_len) {
                         /* Trim it back to the correct length */
-                        ftruncate(dev->fd, device_len);
+                        ftruncate64(dev->fd, device_len);
                         /* Die, bad Guest, die. */
                         errx(1, "Write past end %llu+%u", off, len);
                 }