--- /dev/null
+////////////////////////////////////////////////////////////////////////////
+//
+// Copyright 2017 Realm Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+////////////////////////////////////////////////////////////////////////////
+
+#include "sync/sync_config.hpp"
+
+#include "sync/sync_manager.hpp"
+
+#include <realm/sync/crypto.hpp>
+
+namespace realm {
+
+namespace {
+
+// Construct an identifier for this partially synced Realm by combining client and user identifiers.
+std::string partial_sync_identifier(const SyncUser& user)
+{
+ std::string raw_identifier = SyncManager::shared().client_uuid() + "/" + user.local_identity();
+ uint8_t identifier[20];
+ sync::crypto::sha1(raw_identifier.data(), raw_identifier.size(), (char *)&identifier[0]);
+
+ std::stringstream ss;
+ ss << std::hex << std::setfill('0');
+ for (uint8_t c : identifier)
+ ss << std::setw(2) << (unsigned)c;
+ return ss.str();
+}
+
+} // unnamed namespace
+
+std::string SyncConfig::realm_url() const
+{
+ REALM_ASSERT(reference_realm_url.length() > 0);
+ REALM_ASSERT(user);
+
+ if (!is_partial)
+ return reference_realm_url;
+
+ std::string base_url = reference_realm_url;
+ if (base_url.back() == '/')
+ base_url.pop_back();
+
+ if (custom_partial_sync_identifier)
+ return base_url + "/__partial/" + *custom_partial_sync_identifier;
+
+ return base_url + "/__partial/" + partial_sync_identifier(*user);
+}
+
+} // namespace realm