[Xen-devel] [PATCH v10 04/11] public: xen.h: add definitions for UUID handling

[Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>]

Added type xen_uuid_t. This type represents UUID as an array of 16
bytes in big endian format.

Added macro XEN_DEFINE_UUID that constructs UUID in the usual way:

 XEN_DEFINE_UUID(0x00112233, 0x4455, 0x6677, 0x8899,
                0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff)

will construct UUID 00112233-4455-6677-8899-aabbccddeeff presented as
 {0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88,
  0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff}

NB: We define a new structure here rather than re-using EFI_GUID.
EFI_GUID uses a Microsoft-style encoding which, among other things,
mixes little-endian and big-endian. The structure defined in this
patch, unlike EFI_GUID, is compatible with the Linux kernel and libuuid.

Signed-off-by: Volodymyr Babchuk <volodymyr_babchuk@xxxxxxxx>
---
 * Added check `|| defined(__GNUC__) to
   #if (defined (__STDC_VERSION__) && __STDC_VERSION__ >= 199901L)
---
xen/include/public/xen.h | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/xen/include/public/xen.h b/xen/include/public/xen.h
index 2ac6b1e..e7129fd 100644
--- a/xen/include/public/xen.h
+++ b/xen/include/public/xen.h
@@ -930,6 +930,39 @@ __DEFINE_XEN_GUEST_HANDLE(uint16, uint16_t);
 __DEFINE_XEN_GUEST_HANDLE(uint32, uint32_t);
 __DEFINE_XEN_GUEST_HANDLE(uint64, uint64_t);
 
+typedef struct {
+    uint8_t a[16];
+} xen_uuid_t;
+
+/*
+ * XEN_DEFINE_UUID(0x00112233, 0x4455, 0x6677, 0x8899,
+ *                 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff)
+ * will construct UUID 00112233-4455-6677-8899-aabbccddeeff presented as
+ * {0x00, 0x11, 0x22, 0x33, 0x44, 0x55, 0x66, 0x77, 0x88,
+ * 0x99, 0xaa, 0xbb, 0xcc, 0xdd, 0xee, 0xff};
+ *
+ * NB: This is compatible with Linux kernel and with libuuid, but it is not
+ * compatible with Microsoft, as they use mixed-endian encoding (some
+ * components are little-endian, some are big-endian).
+ */
+#define XEN_DEFINE_UUID_(a, b, c, d, e1, e2, e3, e4, e5, e6)            \
+    {{((a) >> 24) & 0xFF, ((a) >> 16) & 0xFF,                           \
+      ((a) >>  8) & 0xFF, ((a) >>  0) & 0xFF,                           \
+      ((b) >>  8) & 0xFF, ((b) >>  0) & 0xFF,                           \
+      ((c) >>  8) & 0xFF, ((c) >>  0) & 0xFF,                           \
+      ((d) >>  8) & 0xFF, ((d) >>  0) & 0xFF,                           \
+                e1, e2, e3, e4, e5, e6}}
+
+/* Compound literals are supported in C99 and later. */
+#if (defined (__STDC_VERSION__) && __STDC_VERSION__ >= 199901L) ||      \
+    defined (__GNUC__)
+#define XEN_DEFINE_UUID(a, b, c, d, e1, e2, e3, e4, e5, e6)             \
+    ((xen_uuid_t)XEN_DEFINE_UUID_(a, b, c, d, e1, e2, e3, e4, e5, e6))
+#else
+#define XEN_DEFINE_UUID(a, b, c, d, e1, e2, e3, e4, e5, e6)             \
+    XEN_DEFINE_UUID_(a, b, c, d, e1, e2, e3, e4, e5, e6)
+#endif /* defined (__STDC_VERSION__) && __STDC_VERSION__ >= 199901L */
+
 #endif /* !__ASSEMBLY__ */
 
 /* Default definitions for macros used by domctl/sysctl. */
-- 
2.7.4


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