From: Jake Wires <jwires@xensource.com>
Date: Tue, 10 Apr 2007 18:40:43 +0000 (-0700)
Subject: [TAPDISK] Fix qcow initialization bug.
X-Git-Tag: archive/raspbian/4.8.0-1+rpi1~1^2~15252^2~21
X-Git-Url: https://dgit.raspbian.org/%22http:/www.example.com/cgi/%22https:/%22bookmarks://%22Dat/%22http:/www.example.com/cgi/%22https:/%22bookmarks:/%22Dat?a=commitdiff_plain;h=9a549acc99e635fcafb1d797e59ab28c7b53615b;p=xen.git

[TAPDISK] Fix qcow initialization bug.

fd_end was being incorrectly initialized upon open, leading to data corruption.

Signed-off-by: Jake Wires <jwires@xensource.com>
---

diff --git a/tools/blktap/drivers/block-qcow.c b/tools/blktap/drivers/block-qcow.c
index b0822f729d..2e5532a7cb 100644
--- a/tools/blktap/drivers/block-qcow.c
+++ b/tools/blktap/drivers/block-qcow.c
@@ -949,8 +949,14 @@ int tdqcow_open (struct disk_driver *dd, const char *name, td_flag_t flags)
 		goto fail;
 	}
 	init_fds(dd);
-	s->fd_end = (final_cluster == 0 ? (s->l1_table_offset + l1_table_size) : 
-				(final_cluster + s->cluster_size));
+
+	if (!final_cluster)
+		s->fd_end = s->l1_table_offset + l1_table_size;
+	else {
+		s->fd_end = lseek64(fd, 0, SEEK_END);
+		if (s->fd_end == (off64_t)-1)
+			goto fail;
+	}
 
 	return 0;