check kvstore works when opening the db

Author: paul-szczepanek-arm

features/FEATURE_BLE/source/generic/KVStoreSecurityDb.cpp

@@ -63,7 +63,15 @@ KVStoreSecurityDb::~KVStoreSecurityDb() {
 
 bool KVStoreSecurityDb::open_db() {
     uint8_t version = 0;
-    db_read(&version, DB_VERSION);
+    char db_key[DB_FULL_KEY_SIZE];
+    create_key(db_key, DB_VERSION);
+    size_t size;
+    int ret = kv_get(db_key, &version, sizeof(uint8_t), &size);
+
+    /* kvstore problem (check if it's been successfully initialised before this call) */
+    if (ret != MBED_ERROR_ITEM_NOT_FOUND && (ret != MBED_SUCCESS || size != sizeof(uint8_t))) {
+        return false;
+    }
 
     /* wipe the db if it's the wrong version or it doesn't exist */
     if (version != KVSTORESECURITYDB_VERSION) {