[Qemu-devel] [PATCH] block/qcow2.h: Avoid "1LL << 63" (shifts into sign bit)

[Peter Maydell <peter.maydell@linaro.org>]

The expression "1LL << 63" tries to shift the 1 into the sign bit of a
'long long', which provokes a clang sanitizer warning:

runtime error: left shift of 1 by 63 places cannot be represented in type 'long long'

Use "1ULL << 63" as the definition of QCOW_OFLAG_COPIED instead
to avoid this. For consistency, we also update the other QCOW_OFLAG
definitions to use the ULL suffix rather than LL, though only the
shift by 63 is undefined behaviour.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
---
 block/qcow2.h |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/block/qcow2.h b/block/qcow2.h
index dba9771..365a17e 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -40,11 +40,11 @@
 #define QCOW_MAX_CRYPT_CLUSTERS 32
 
 /* indicate that the refcount of the referenced cluster is exactly one. */
-#define QCOW_OFLAG_COPIED     (1LL << 63)
+#define QCOW_OFLAG_COPIED     (1ULL << 63)
 /* indicate that the cluster is compressed (they never have the copied flag) */
-#define QCOW_OFLAG_COMPRESSED (1LL << 62)
+#define QCOW_OFLAG_COMPRESSED (1ULL << 62)
 /* The cluster reads as all zeros */
-#define QCOW_OFLAG_ZERO (1LL << 0)
+#define QCOW_OFLAG_ZERO (1ULL << 0)
 
 #define REFCOUNT_SHIFT 1 /* refcount size is 2 bytes */
 
-- 
1.7.9.5