util: storage: Add support for host device backing specified via JSON

JSON pseudo protocol for qemu allows to explicitly specify devices.
Add convertor to the internal type.

src/util/virstoragefile.c

@@ -2545,6 +2545,8 @@ struct virStorageSourceJSONDriverParser {
 
 static const struct virStorageSourceJSONDriverParser jsonParsers[] = {
     {"file", virStorageSourceParseBackingJSONPath, VIR_STORAGE_TYPE_FILE},
+    {"host_device", virStorageSourceParseBackingJSONPath, VIR_STORAGE_TYPE_BLOCK},
+    {"host_cdrom", virStorageSourceParseBackingJSONPath, VIR_STORAGE_TYPE_BLOCK},
 };
 
 

tests/virstoragetest.c

@@ -1370,6 +1370,12 @@ mymain(void)
                                         "}"
                             "}",
                        "<source file='/path/to/file'/>\n");
+    TEST_BACKING_PARSE("json:{\"file.driver\":\"host_device\", "
+                             "\"file.filename\":\"/path/to/dev\"}",
+                       "<source dev='/path/to/dev'/>\n");
+    TEST_BACKING_PARSE("json:{\"file.driver\":\"host_cdrom\", "
+                             "\"file.filename\":\"/path/to/cdrom\"}",
+                       "<source dev='/path/to/cdrom'/>\n");
 
  cleanup:
     /* Final cleanup */