Add RealmConfig::needs_file_format_upgrade (#7336)

CHANGELOG.md

@@ -7,6 +7,7 @@
 * Updated bundled OpenSSL version to 3.2.0 (PR [#7303](https://github.com/realm/realm-core/pull/7303))
 * Added `SyncSession::get_file_ident()` so you can trigger a client reset via the BAAS admin API ([PR #7203](https://github.com/realm/realm-core/pull/7203)).
 * Audit event scopes containing zero events to save no longer open the audit realm unneccesarily ([PR #7332](https://github.com/realm/realm-core/pull/7332)).
+* Added a method to check if a file needs upgrade. ([#7140](https://github.com/realm/realm-core/issues/7140))
 
 ### Fixed
 * Uploading the changesets recovered during an automatic client reset recovery may lead to 'Bad server version' errors and a new client reset. ([#7279](https://github.com/realm/realm-core/issues/7279), since v13.24.1)

bindgen/spec.yml

@@ -691,6 +691,7 @@ classes:
       # Converts char* and length to a combined string_view argument to callback.
       # TODO: Consider making preverify_ok a bool.
       make_ssl_verify_callback: '(callback: (server_address: const std::string&, server_port: int, pem_data: std::string_view, preverify_ok: int, depth: int) off_thread -> bool) -> SSLVerifyCallback'
+      needs_file_format_upgrade: '(config: const RealmConfig&) -> bool'
 
   Logger:
     cppName: util::Logger

bindgen/src/realm_helpers.h

@@ -278,6 +278,11 @@ struct Helpers {
             return callback(server_address, server_port, std::string_view(pem_data, pem_size), preverify_ok, depth);
         };
     }
+
+    static bool needs_file_format_upgrade(const RealmConfig& config)
+    {
+        return config.needs_file_format_upgrade();
+    }
 };
 
 struct ObjectChangeSet {

src/realm.h

@@ -775,6 +775,11 @@ RLM_API void realm_config_set_should_compact_on_launch_function(realm_config_t*,
  */
 RLM_API bool realm_config_get_disable_format_upgrade(const realm_config_t*);
 
+/**
+ * True if you can open the file without a file_format_upgrade
+ */
+RLM_API bool realm_config_needs_file_format_upgrade(const realm_config_t*);
+
 /**
  * Disable file format upgrade on open (default: false).
  *

src/realm/db.cpp

@@ -2146,6 +2146,31 @@ void DB::enable_wait_for_change()
     m_wait_for_change_enabled = true;
 }
 
+bool DB::needs_file_format_upgrade(const std::string& file, const std::vector<char>& encryption_key)
+{
+    SlabAlloc alloc;
+    SlabAlloc::Config cfg;
+    cfg.session_initiator = false;
+    cfg.read_only = true;
+    cfg.no_create = true;
+    if (!encryption_key.empty()) {
+        cfg.encryption_key = encryption_key.data();
+    }
+    try {
+        alloc.attach_file(file, cfg);
+        if (auto current_file_format_version = alloc.get_committed_file_format_version()) {
+            auto target_file_format_version = Group::g_current_file_format_version;
+            return current_file_format_version < target_file_format_version;
+        }
+    }
+    catch (const FileAccessError& err) {
+        if (err.code() != ErrorCodes::FileNotFound) {
+            throw;
+        }
+    }
+    return false;
+}
+
 void DB::upgrade_file_format(bool allow_file_format_upgrade, int target_file_format_version,
                              int current_hist_schema_version, int target_hist_schema_version)
 {

src/realm/db.hpp

@@ -167,6 +167,8 @@ class DB : public std::enable_shared_from_this<DB> {
 
     bool is_attached() const noexcept;
 
+    static bool needs_file_format_upgrade(const std::string& file, const std::vector<char>& encryption_key);
+
     Allocator& get_alloc()
     {
         return m_alloc;

src/realm/object-store/c_api/config.cpp

@@ -163,6 +163,11 @@ RLM_API bool realm_config_get_disable_format_upgrade(const realm_config_t* confi
     return config->disable_format_upgrade;
 }
 
+RLM_API bool realm_config_needs_file_format_upgrade(const realm_config_t* config)
+{
+    return config->needs_file_format_upgrade();
+}
+
 RLM_API void realm_config_set_disable_format_upgrade(realm_config_t* config, bool b)
 {
     config->disable_format_upgrade = b;

src/realm/object-store/shared_realm.cpp

@@ -77,6 +77,11 @@ class CountGuard {
 };
 } // namespace
 
+bool RealmConfig::needs_file_format_upgrade() const
+{
+    return DB::needs_file_format_upgrade(path, encryption_key);
+}
+
 Realm::Realm(Config config, util::Optional<VersionID> version, std::shared_ptr<_impl::RealmCoordinator> coordinator,
              Private)
     : m_config(std::move(config))

src/realm/object-store/shared_realm.hpp

@@ -138,6 +138,8 @@ struct RealmConfig {
         return schema_mode == SchemaMode::ReadOnly;
     }
 
+    bool needs_file_format_upgrade() const;
+
     // If false, always return a new Realm instance, and don't return
     // that Realm instance for other requests for a cached Realm. Useful
     // for dynamic Realms and for tests that need multiple instances on

test/object-store/migrations.cpp

@@ -2052,7 +2052,11 @@ TEST_CASE("migration: SoftResetFile", "[migration]") {
         ObjectStore::table_for_object_type(realm->read_group(), "object")->create_object();
         realm->commit_transaction();
     }
-    auto realm = Realm::get_shared_realm(config);
+    SharedRealm realm;
+    if (!config.needs_file_format_upgrade()) {
+        realm = Realm::get_shared_realm(config);
+    }
+    REQUIRE(realm);
     auto ino = get_fileid();
 
     SECTION("file is reset when schema version increases") {

test/test_shared.cpp

@@ -634,16 +634,25 @@ TEST(Shared_EncryptedRemap)
 TEST(Shared_Initial)
 {
     SHARED_GROUP_TEST_PATH(path);
+    std::vector<char> key;
+
+    CHECK_NOT(DB::needs_file_format_upgrade(path, key)); // File not created yet
+
+    auto key_str = crypt_key();
     {
         // Create a new shared db
-        DBRef sg = DB::create(path, false, DBOptions(crypt_key()));
+        DBRef sg = DB::create(path, false, DBOptions(key_str));
 
         // Verify that new group is empty
         {
             ReadTransaction rt(sg);
             CHECK(rt.get_group().is_empty());
         }
     }
+    if (key_str) {
+        key.insert(key.end(), key_str, key_str + strlen(key_str));
+    }
+    CHECK_NOT(DB::needs_file_format_upgrade(path, key));
 }
 
 

test/test_upgrade_database.cpp

@@ -1317,6 +1317,7 @@ TEST_IF(Upgrade_Database_22, REALM_MAX_BPNODE_SIZE == 4 || REALM_MAX_BPNODE_SIZE
     // Make a copy of the database so that we keep the original file intact and unmodified
     File::copy(path, temp_copy);
     auto hist = make_in_realm_history();
+    CHECK(DB::needs_file_format_upgrade(temp_copy, {}));
     auto sg = DB::create(*hist, temp_copy);
     auto rt = sg->start_read();