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authorFam Zheng <famz@redhat.com>2014-12-04 07:28:29 +0800
committerKevin Wolf <kwolf@redhat.com>2014-12-10 10:31:21 +0100
commite5dc64b8ff09cc4c186273e4461c7479739db2ae (patch)
tree058e90cb948f0d65a1af2959a815c2d95620c6b3
parent3ba235a02284c39b34a68a2a588508ffb52a7b55 (diff)
downloadfocaccia-qemu-e5dc64b8ff09cc4c186273e4461c7479739db2ae.tar.gz
focaccia-qemu-e5dc64b8ff09cc4c186273e4461c7479739db2ae.zip
vmdk: Use g_random_int to generate CID
This replaces two "time(NULL)" invocations with "g_random_int()".
According to VMDK spec, CID "is a random 32‐bit value updated the first
time the content of the virtual disk is modified after the virtual disk
is opened". Using "seconds since epoch" is just a "lame way" to generate
it, and not completely safe because of the low precision.

Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Fam Zheng <famz@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Don Koch <dkoch@verizon.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Message-id: 1417649314-13704-2-git-send-email-famz@redhat.com
Signed-off-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
-rw-r--r--block/vmdk.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/block/vmdk.c b/block/vmdk.c
index 2cbfd3e72e..ebb4b705f5 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -28,6 +28,7 @@
 #include "qemu/module.h"
 #include "migration/migration.h"
 #include <zlib.h>
+#include <glib.h>
 
 #define VMDK3_MAGIC (('C' << 24) | ('O' << 16) | ('W' << 8) | 'D')
 #define VMDK4_MAGIC (('K' << 24) | ('D' << 16) | ('M' << 8) | 'V')
@@ -1538,7 +1539,7 @@ static int vmdk_write(BlockDriverState *bs, int64_t sector_num,
         /* update CID on the first write every time the virtual disk is
          * opened */
         if (!s->cid_updated) {
-            ret = vmdk_write_cid(bs, time(NULL));
+            ret = vmdk_write_cid(bs, g_random_int());
             if (ret < 0) {
                 return ret;
             }
@@ -1922,7 +1923,7 @@ static int vmdk_create(const char *filename, QemuOpts *opts, Error **errp)
     }
     /* generate descriptor file */
     desc = g_strdup_printf(desc_template,
-                           (uint32_t)time(NULL),
+                           g_random_int(),
                            parent_cid,
                            fmt,
                            parent_desc_line,