[Xen-devel] [PATCH v2 2/2] libxl: fix UUID usage on FreeBSD

[Roger Pau Monne <roger.pau@xxxxxxxxxx>]

libxl makes the assumtion that libxl_uuid == uuid_t, and that uuid_t can be
freely used as a byte array. This is not true on FreeBSD (and NetBSD
too, not sure about other BSD UUID implementations), where the internals of
uuid don't match what libxl expects as a byte array because of endianness
issues.

Fix this by converting the libxl_uuid type to a struct with an internal
uuid_t field and a byte-array. Also introduce a new function that should be
used in order to load a byte array into a uuid_t struct.

Signed-off-by: Roger Pau Monnà <roger.pau@xxxxxxxxxx>
---
Cc: Ian Jackson <ian.jackson@xxxxxxxxxxxxx>
Cc: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Cc: Ian Campbell <ian.campbell@xxxxxxxxxx>
Cc: Wei Liu <wei.liu2@xxxxxxxxxx>
---
 tools/libxl/libxl.c      |  2 +-
 tools/libxl/libxl.h      |  9 +++++++++
 tools/libxl/libxl_uuid.c | 22 +++++++++++++++++++---
 tools/libxl/libxl_uuid.h |  3 ++-
 4 files changed, 31 insertions(+), 5 deletions(-)

diff --git a/tools/libxl/libxl.c b/tools/libxl/libxl.c
index 9207621..ae08b2f 100644
--- a/tools/libxl/libxl.c
+++ b/tools/libxl/libxl.c
@@ -616,7 +616,7 @@ static void xcinfo2xlinfo(libxl_ctx *ctx,
 {
     size_t size;
 
-    memcpy(&(xlinfo->uuid), xcinfo->handle, sizeof(xen_domain_handle_t));
+    libxl_uuid_from_bytearray(&xlinfo->uuid, xcinfo->handle);
     xlinfo->domid = xcinfo->domain;
     xlinfo->ssidref = xcinfo->ssidref;
     if (libxl_flask_sid_to_context(ctx, xlinfo->ssidref,
diff --git a/tools/libxl/libxl.h b/tools/libxl/libxl.h
index 05606a7..876fca8 100644
--- a/tools/libxl/libxl.h
+++ b/tools/libxl/libxl.h
@@ -867,6 +867,15 @@ void libxl_mac_copy(libxl_ctx *ctx, libxl_mac *dst, 
libxl_mac *src);
  */
 #define LIBXL_HAVE_DEVICE_MODEL_VERSION_NONE 1
 
+/*
+ * LIBXL_HAVE_UUID_FROM_BYTEARRAY
+ *
+ * In the case that LIBXL_HAVE_UUID_FROM_BYTEARRAY is set libxl
+ * provides a function (libxl_uuid_from_bytearray) to convert an
+ * octet stream into a UUID.
+ */
+#define LIBXL_HAVE_UUID_FROM_BYTEARRAY 1
+
 typedef char **libxl_string_list;
 void libxl_string_list_dispose(libxl_string_list *sl);
 int libxl_string_list_length(const libxl_string_list *sl);
diff --git a/tools/libxl/libxl_uuid.c b/tools/libxl/libxl_uuid.c
index 7d4a032..f566f50 100644
--- a/tools/libxl/libxl_uuid.c
+++ b/tools/libxl/libxl_uuid.c
@@ -33,6 +33,12 @@ int libxl_uuid_from_string(libxl_uuid *uuid, const char *in)
      return uuid_parse(in, uuid->uuid);
 }
 
+int libxl_uuid_from_bytearray(libxl_uuid *uuid, const uint8_t *raw)
+{
+    memcpy(uuid, raw, sizeof(*uuid));
+    return 0;
+}
+
 void libxl_uuid_copy(libxl_ctx *ctx_opt, libxl_uuid *dst,
                      const libxl_uuid *src)
 {
@@ -72,9 +78,9 @@ void libxl_uuid_generate(libxl_uuid *uuid)
 {
     uint32_t status;
 
-    BUILD_BUG_ON(sizeof(libxl_uuid) != sizeof(uuid_t));
     uuid_create(&uuid->uuid, &status);
     assert(status == uuid_s_ok);
+    uuid_enc_be(uuid->uuid_raw, &uuid->uuid);
 }
 
 #ifdef __FreeBSD__
@@ -85,6 +91,8 @@ int libxl_uuid_from_string(libxl_uuid *uuid, const char *in)
     uuid_from_string(in, &uuid->uuid, &status);
     if (status != uuid_s_ok)
         return -1;
+    uuid_enc_be(uuid->uuid_raw, &uuid->uuid);
+
     return 0;
 }
 #else
@@ -101,15 +109,23 @@ int libxl_uuid_from_string(libxl_uuid *uuid, const char 
*in)
 #undef LIBXL__UUID_PTRS
 #endif
 
+int libxl_uuid_from_bytearray(libxl_uuid *uuid, const uint8_t *raw)
+{
+    uuid_dec_le(raw, &uuid->uuid);
+    uuid_enc_be(uuid->uuid_raw, &uuid->uuid);
+
+    return 0;
+}
+
 void libxl_uuid_copy(libxl_ctx *ctx_opt, libxl_uuid *dst,
                      const libxl_uuid *src)
 {
-    memcpy(&dst->uuid, &src->uuid, sizeof(dst->uuid));
+    memcpy(dst, src, sizeof(*dst));
 }
 
 void libxl_uuid_clear(libxl_uuid *uuid)
 {
-    memset(&uuid->uuid, 0, sizeof(uuid->uuid));
+    memset(uuid, 0, sizeof(*uuid));
 }
 
 #ifdef __FreeBSD__
diff --git a/tools/libxl/libxl_uuid.h b/tools/libxl/libxl_uuid.h
index c5041c7..d84e3d1 100644
--- a/tools/libxl/libxl_uuid.h
+++ b/tools/libxl/libxl_uuid.h
@@ -42,7 +42,7 @@ typedef struct {
 #include <stdio.h>
 #include <assert.h>
 
-typedef union {
+typedef struct {
     uuid_t uuid;
     uint8_t uuid_raw[16];
 } libxl_uuid;
@@ -73,6 +73,7 @@ void libxl_uuid_clear(libxl_uuid *uuid);
 int libxl_uuid_compare(const libxl_uuid *uuid1, const libxl_uuid *uuid2);
 const uint8_t *libxl_uuid_bytearray_const(const libxl_uuid *uuid);
 uint8_t *libxl_uuid_bytearray(libxl_uuid *uuid);
+int libxl_uuid_from_bytearray(libxl_uuid *uuid, const uint8_t *raw);
 
 #endif /* __LIBXL_UUID_H__ */
 
-- 
1.9.5 (Apple Git-50.3)


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