[Tarantool-patches] [PATCH 2/2] uuid: fix unaligned memory access

[Vladislav Shpilevoy <v.shpilevoy@tarantool.org>]

Functions tt_uuid_is_nil() and tt_uuid_is_equal() used struct
tt_uuid as an array of two uint64. But it is wrong, because struct
tt_uuid has 4 byte alignment, while uint64 requires 8. That led to
unaligned memory access in these 2 functions.

The patch makes these functions treat struct tt_uuid as 4 uint32
instead of 2 uint64.

Part of #4609
---
 src/lib/uuid/tt_uuid.h | 11 ++++++-----
 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/src/lib/uuid/tt_uuid.h b/src/lib/uuid/tt_uuid.h
index c2c436ed4..d62991c65 100644
--- a/src/lib/uuid/tt_uuid.h
+++ b/src/lib/uuid/tt_uuid.h
@@ -158,8 +158,8 @@ tt_uuid_bswap(struct tt_uuid *uu)
 inline bool
 tt_uuid_is_nil(const struct tt_uuid *uu)
 {
-	const uint64_t *p = (const uint64_t *) uu;
-	return !p[0] && !p[1];
+	const uint32_t *p = (const uint32_t *) uu;
+	return p[0] == 0 && p[1] == 0 && p[2] == 0 && p[3] == 0;
 }
 
 /**
@@ -172,9 +172,10 @@ tt_uuid_is_nil(const struct tt_uuid *uu)
 inline bool
 tt_uuid_is_equal(const struct tt_uuid *lhs, const struct tt_uuid *rhs)
 {
-	const uint64_t *lp = (const uint64_t *) lhs;
-	const uint64_t *rp = (const uint64_t *) rhs;
-	return lp[0] == rp[0] && lp[1] == rp[1];
+	const uint32_t *lp = (const uint32_t *) lhs;
+	const uint32_t *rp = (const uint32_t *) rhs;
+	return lp[0] == rp[0] && lp[1] == rp[1] && lp[2] == rp[2] &&
+	       lp[3] == rp[3];
 }
 
 extern const struct tt_uuid uuid_nil;
-- 
2.21.1 (Apple Git-122.3)