[core] harden OfflineDatabase

16 files changed, 1150 insertions, 352 deletions

diff --git a/cmake/test-files.cmake b/cmake/test-files.cmake
index 2a679fc40b..ff659b1cd1 100644
--- a/cmake/test-files.cmake
+++ b/cmake/test-files.cmake
@@ -95,6 +95,8 @@ set(MBGL_TEST_FILES
     test/src/mbgl/test/fixture_log_observer.hpp
     test/src/mbgl/test/getrss.cpp
     test/src/mbgl/test/getrss.hpp
+    test/src/mbgl/test/sqlite3_test_fs.cpp
+    test/src/mbgl/test/sqlite3_test_fs.hpp
     test/src/mbgl/test/stub_file_source.cpp
     test/src/mbgl/test/stub_file_source.hpp
     test/src/mbgl/test/stub_geometry_tile_feature.hpp
diff --git a/include/mbgl/storage/offline.hpp b/include/mbgl/storage/offline.hpp
index ef4a499e83..2193f8d09e 100644
--- a/include/mbgl/storage/offline.hpp
+++ b/include/mbgl/storage/offline.hpp
@@ -187,11 +187,11 @@ class OfflineRegion {
 public:
     // Move-only; not publicly constructible.
     OfflineRegion(OfflineRegion&&);
-    OfflineRegion& operator=(OfflineRegion&&);
     ~OfflineRegion();
 
     OfflineRegion() = delete;
     OfflineRegion(const OfflineRegion&) = delete;
+    OfflineRegion& operator=(OfflineRegion&&) = delete;
     OfflineRegion& operator=(const OfflineRegion&) = delete;
 
     int64_t getID() const;
diff --git a/platform/default/default_file_source.cpp b/platform/default/default_file_source.cpp
index f070121497..051e1b125c 100644
--- a/platform/default/default_file_source.cpp
+++ b/platform/default/default_file_source.cpp
@@ -74,9 +74,9 @@ public:
     }
 
     void getRegionStatus(int64_t regionID, std::function<void (std::exception_ptr, optional<OfflineRegionStatus>)> callback) {
-        try {
-            callback({}, getDownload(regionID).getStatus());
-        } catch (...) {
+        if (auto download = getDownload(regionID)) {
+            callback({}, download->getStatus());
+        } else {
             callback(std::current_exception(), {});
         }
     }
@@ -92,11 +92,15 @@ public:
     }
 
     void setRegionObserver(int64_t regionID, std::unique_ptr<OfflineRegionObserver> observer) {
-        getDownload(regionID).setObserver(std::move(observer));
+        if (auto download = getDownload(regionID)) {
+            download->setObserver(std::move(observer));
+        }
     }
 
     void setRegionDownloadState(int64_t regionID, OfflineRegionDownloadState state) {
-        getDownload(regionID).setState(state);
+        if (auto download = getDownload(regionID)) {
+            download->setState(state);
+        }
     }
 
     void request(AsyncRequest* req, Resource resource, ActorRef<FileSourceRequest> ref) {
@@ -181,13 +185,19 @@ public:
     }
 
 private:
-    OfflineDownload& getDownload(int64_t regionID) {
+    OfflineDownload* getDownload(int64_t regionID) {
         auto it = downloads.find(regionID);
         if (it != downloads.end()) {
-            return *it->second;
+            return it->second.get();
+        }
+        auto definition = offlineDatabase->getRegionDefinition(regionID);
+        if (!definition) {
+            return nullptr;
         }
-        return *downloads.emplace(regionID,
-            std::make_unique<OfflineDownload>(regionID, offlineDatabase->getRegionDefinition(regionID), *offlineDatabase, onlineFileSource)).first->second;
+
+        auto download = std::make_unique<OfflineDownload>(regionID, std::move(*definition),
+                                                          *offlineDatabase, onlineFileSource);
+        return downloads.emplace(regionID, std::move(download)).first->second.get();
     }
 
     // shared so that destruction is done on the creating thread
diff --git a/platform/default/mbgl/storage/offline_database.cpp b/platform/default/mbgl/storage/offline_database.cpp
index 8f7f0965f4..cfa7f52977 100644
--- a/platform/default/mbgl/storage/offline_database.cpp
+++ b/platform/default/mbgl/storage/offline_database.cpp
@@ -15,7 +15,14 @@ namespace mbgl {
 OfflineDatabase::OfflineDatabase(std::string path_, uint64_t maximumCacheSize_)
     : path(std::move(path_)),
       maximumCacheSize(maximumCacheSize_) {
-    ensureSchema();
+    try {
+        initialize();
+    } catch (const util::IOException& ex) {
+        handleError(ex, "open database");
+    } catch (const mapbox::sqlite::Exception& ex) {
+        handleError(ex, "open database");
+    }
+    // Assume that we can't open the database right now and work with an empty database object.
 }
 
 OfflineDatabase::~OfflineDatabase() {
@@ -24,87 +31,71 @@ OfflineDatabase::~OfflineDatabase() {
     try {
         statements.clear();
         db.reset();
-    } catch (mapbox::sqlite::Exception& ex) {
-        Log::Error(Event::Database, (int)ex.code, ex.what());
+    } catch (const util::IOException& ex) {
+        handleError(ex, "close database");
+    } catch (const mapbox::sqlite::Exception& ex) {
+        handleError(ex, "close database");
     }
 }
 
-void OfflineDatabase::ensureSchema() {
-    auto result = mapbox::sqlite::Database::tryOpen(path, mapbox::sqlite::ReadWriteCreate);
-    if (result.is<mapbox::sqlite::Exception>()) {
-        const auto& ex = result.get<mapbox::sqlite::Exception>();
-        if (ex.code == mapbox::sqlite::ResultCode::NotADB) {
-            // Corrupted; blow it away.
-            removeExisting();
-            result = mapbox::sqlite::Database::open(path, mapbox::sqlite::ReadWriteCreate);
-        } else {
-            Log::Error(Event::Database, "Unexpected error connecting to database: %s", ex.what());
-            throw ex;
-        }
+void OfflineDatabase::initialize() {
+    assert(!db);
+    assert(statements.empty());
+
+    db = std::make_unique<mapbox::sqlite::Database>(
+        mapbox::sqlite::Database::open(path, mapbox::sqlite::ReadWriteCreate));
+    db->setBusyTimeout(Milliseconds::max());
+    db->exec("PRAGMA foreign_keys = ON");
+
+    const auto userVersion = getPragma<int64_t>("PRAGMA user_version");
+    switch (userVersion) {
+    case 0:
+    case 1:
+        // Newly created database, or old cache-only database; remove old table if it exists.
+        removeOldCacheTable();
+        createSchema();
+        return;
+    case 2:
+        migrateToVersion3();
+        // fall through
+    case 3:
+        // Removed migration, see below.
+        // fall through
+    case 4:
+        migrateToVersion5();
+        // fall through
+    case 5:
+        migrateToVersion6();
+        // fall through
+    case 6:
+        // Happy path; we're done
+        return;
+    default:
+        // Downgrade: delete the database and try to reinitialize.
+        removeExisting();
+        initialize();
     }
+}
 
-    try {
-        assert(result.is<mapbox::sqlite::Database>());
-        db = std::make_unique<mapbox::sqlite::Database>(std::move(result.get<mapbox::sqlite::Database>()));
-        db->setBusyTimeout(Milliseconds::max());
-        db->exec("PRAGMA foreign_keys = ON");
-
-        switch (userVersion()) {
-        case 0:
-        case 1:
-            // Newly created database, or old cache-only database; remove old table if it exists.
-            removeOldCacheTable();
-            break;
-        case 2:
-            migrateToVersion3();
-            // fall through
-        case 3:
-        case 4:
-            migrateToVersion5();
-            // fall through
-        case 5:
-            migrateToVersion6();
-            // fall through
-        case 6:
-            // happy path; we're done
-            return;
-        default:
-            // downgrade, delete the database
-            removeExisting();
-            break;
-        }
-    } catch (const mapbox::sqlite::Exception& ex) {
-        // Unfortunately, SQLITE_NOTADB is not always reported upon opening the database.
-        // Apparently sometimes it is delayed until the first read operation.
-        if (ex.code == mapbox::sqlite::ResultCode::NotADB) {
+void OfflineDatabase::handleError(const mapbox::sqlite::Exception& ex, const char* action) {
+    if (ex.code == mapbox::sqlite::ResultCode::NotADB ||
+        ex.code == mapbox::sqlite::ResultCode::Corrupt) {
+        // Corrupted; delete database so that we have a clean slate for the next operation.
+        Log::Error(Event::Database, static_cast<int>(ex.code), "Can't %s: %s", action, ex.what());
+        try {
             removeExisting();
-        } else {
-            throw;
+        } catch (const util::IOException& ioEx) {
+            handleError(ioEx, action);
         }
-    }
-
-    try {
-        // When downgrading the database, or when the database is corrupt, we've deleted the old database handle,
-        // so we need to reopen it.
-        if (!db) {
-            db = std::make_unique<mapbox::sqlite::Database>(mapbox::sqlite::Database::open(path, mapbox::sqlite::ReadWriteCreate));
-            db->setBusyTimeout(Milliseconds::max());
-            db->exec("PRAGMA foreign_keys = ON");
-        }
-
-        db->exec("PRAGMA auto_vacuum = INCREMENTAL");
-        db->exec("PRAGMA journal_mode = DELETE");
-        db->exec("PRAGMA synchronous = FULL");
-        db->exec(offlineDatabaseSchema);
-        db->exec("PRAGMA user_version = 6");
-    } catch (...) {
-        Log::Error(Event::Database, "Unexpected error creating database schema: %s", util::toString(std::current_exception()).c_str());
-        throw;
+    } else {
+        // We treat the error as temporary, and pretend we have an inaccessible DB.
+        Log::Warning(Event::Database, static_cast<int>(ex.code), "Can't %s: %s", action, ex.what());
     }
 }
 
-int OfflineDatabase::userVersion() {
-    return static_cast<int>(getPragma<int64_t>("PRAGMA user_version"));
+void OfflineDatabase::handleError(const util::IOException& ex, const char* action) {
+    // We failed to delete the database file.
+    Log::Error(Event::Database, ex.code, "Can't %s: %s", action, ex.what());
 }
 
 void OfflineDatabase::removeExisting() {
@@ -113,19 +104,28 @@ void OfflineDatabase::removeExisting() {
     statements.clear();
     db.reset();
 
-    try {
-        util::deleteFile(path);
-    } catch (util::IOException& ex) {
-        Log::Error(Event::Database, ex.code, ex.what());
-    }
+    util::deleteFile(path);
 }
 
 void OfflineDatabase::removeOldCacheTable() {
+    assert(db);
     db->exec("DROP TABLE IF EXISTS http_cache");
     db->exec("VACUUM");
 }
 
+void OfflineDatabase::createSchema() {
+    assert(db);
+    db->exec("PRAGMA auto_vacuum = INCREMENTAL");
+    db->exec("PRAGMA journal_mode = DELETE");
+    db->exec("PRAGMA synchronous = FULL");
+    mapbox::sqlite::Transaction transaction(*db);
+    db->exec(offlineDatabaseSchema);
+    db->exec("PRAGMA user_version = 6");
+    transaction.commit();
+}
+
 void OfflineDatabase::migrateToVersion3() {
+    assert(db);
     db->exec("PRAGMA auto_vacuum = INCREMENTAL");
     db->exec("VACUUM");
     db->exec("PRAGMA user_version = 3");
@@ -138,12 +138,14 @@ void OfflineDatabase::migrateToVersion3() {
 // See: https://github.com/mapbox/mapbox-gl-native/pull/6320
 
 void OfflineDatabase::migrateToVersion5() {
+    assert(db);
     db->exec("PRAGMA journal_mode = DELETE");
     db->exec("PRAGMA synchronous = FULL");
     db->exec("PRAGMA user_version = 5");
 }
 
 void OfflineDatabase::migrateToVersion6() {
+    assert(db);
     mapbox::sqlite::Transaction transaction(*db);
     db->exec("ALTER TABLE resources ADD COLUMN must_revalidate INTEGER NOT NULL DEFAULT 0");
     db->exec("ALTER TABLE tiles ADD COLUMN must_revalidate INTEGER NOT NULL DEFAULT 0");
@@ -152,6 +154,9 @@ void OfflineDatabase::migrateToVersion6() {
 }
 
 mapbox::sqlite::Statement& OfflineDatabase::getStatement(const char* sql) {
+    if (!db) {
+        initialize();
+    }
     auto it = statements.find(sql);
     if (it == statements.end()) {
         it = statements.emplace(sql, std::make_unique<mapbox::sqlite::Statement>(*db, sql)).first;
@@ -159,9 +164,15 @@ mapbox::sqlite::Statement& OfflineDatabase::getStatement(const char* sql) {
     return *it->second;
 }
 
-optional<Response> OfflineDatabase::get(const Resource& resource) {
+optional<Response> OfflineDatabase::get(const Resource& resource) try {
     auto result = getInternal(resource);
-    return result ? result->first : optional<Response>();
+    return result ? optional<Response>{ result->first } : nullopt;
+} catch (const util::IOException& ex) {
+    handleError(ex, "read resource");
+    return nullopt;
+} catch (const mapbox::sqlite::Exception& ex) {
+    handleError(ex, "read resource");
+    return nullopt;
 }
 
 optional<std::pair<Response, uint64_t>> OfflineDatabase::getInternal(const Resource& resource) {
@@ -182,11 +193,17 @@ optional<int64_t> OfflineDatabase::hasInternal(const Resource& resource) {
     }
 }
 
-std::pair<bool, uint64_t> OfflineDatabase::put(const Resource& resource, const Response& response) {
+std::pair<bool, uint64_t> OfflineDatabase::put(const Resource& resource, const Response& response) try {
+    if (!db) {
+        initialize();
+    }
     mapbox::sqlite::Transaction transaction(*db, mapbox::sqlite::Transaction::Immediate);
     auto result = putInternal(resource, response, true);
     transaction.commit();
     return result;
+} catch (const mapbox::sqlite::Exception& ex) {
+    handleError(ex, "write resource");
+    return { false, 0 };
 }
 
 std::pair<bool, uint64_t> OfflineDatabase::putInternal(const Resource& resource, const Response& response, bool evict_) {
@@ -227,11 +244,19 @@ std::pair<bool, uint64_t> OfflineDatabase::putInternal(const Resource& resource,
 
 optional<std::pair<Response, uint64_t>> OfflineDatabase::getResource(const Resource& resource) {
     // Update accessed timestamp used for LRU eviction.
-    {
+    try {
         mapbox::sqlite::Query accessedQuery{ getStatement("UPDATE resources SET accessed = ?1 WHERE url = ?2") };
         accessedQuery.bind(1, util::now());
         accessedQuery.bind(2, resource.url);
         accessedQuery.run();
+    } catch (const mapbox::sqlite::Exception& ex) {
+        if (ex.code == mapbox::sqlite::ResultCode::NotADB ||
+            ex.code == mapbox::sqlite::ResultCode::Corrupt) {
+            throw;
+        }
+
+        // If we don't have any indication that the database is corrupt, continue as usual.
+        Log::Warning(Event::Database, static_cast<int>(ex.code), "Can't update timestamp: %s", ex.what());
     }
 
     // clang-format off
@@ -245,7 +270,7 @@ optional<std::pair<Response, uint64_t>> OfflineDatabase::getResource(const Resou
     query.bind(1, resource.url);
 
     if (!query.run()) {
-        return {};
+        return nullopt;
     }
 
     Response response;
@@ -274,7 +299,7 @@ optional<int64_t> OfflineDatabase::hasResource(const Resource& resource) {
     mapbox::sqlite::Query query{ getStatement("SELECT length(data) FROM resources WHERE url = ?") };
     query.bind(1, resource.url);
     if (!query.run()) {
-        return {};
+        return nullopt;
     }
 
     return query.get<optional<int64_t>>(0);
@@ -366,7 +391,8 @@ bool OfflineDatabase::putResource(const Resource& resource,
 }
 
 optional<std::pair<Response, uint64_t>> OfflineDatabase::getTile(const Resource::TileData& tile) {
-    {
+    // Update accessed timestamp used for LRU eviction.
+    try {
         // clang-format off
         mapbox::sqlite::Query accessedQuery{ getStatement(
             "UPDATE tiles "
@@ -385,6 +411,13 @@ optional<std::pair<Response, uint64_t>> OfflineDatabase::getTile(const Resource:
         accessedQuery.bind(5, tile.y);
         accessedQuery.bind(6, tile.z);
         accessedQuery.run();
+    } catch (const mapbox::sqlite::Exception& ex) {
+        if (ex.code == mapbox::sqlite::ResultCode::NotADB || ex.code == mapbox::sqlite::ResultCode::Corrupt) {
+            throw;
+        }
+
+        // If we don't have any indication that the database is corrupt, continue as usual.
+        Log::Warning(Event::Database, static_cast<int>(ex.code), "Can't update timestamp: %s", ex.what());
     }
 
     // clang-format off
@@ -406,7 +439,7 @@ optional<std::pair<Response, uint64_t>> OfflineDatabase::getTile(const Resource:
     query.bind(5, tile.z);
 
     if (!query.run()) {
-        return {};
+        return nullopt;
     }
 
     Response response;
@@ -450,7 +483,7 @@ optional<int64_t> OfflineDatabase::hasTile(const Resource::TileData& tile) {
     size.bind(5, tile.z);
 
     if (!size.run()) {
-        return {};
+        return nullopt;
     }
 
     return size.get<optional<int64_t>>(0);
@@ -559,23 +592,30 @@ bool OfflineDatabase::putTile(const Resource::TileData& tile,
     return true;
 }
 
-std::vector<OfflineRegion> OfflineDatabase::listRegions() {
+std::vector<OfflineRegion> OfflineDatabase::listRegions() try {
     mapbox::sqlite::Query query{ getStatement("SELECT id, definition, description FROM regions") };
-
     std::vector<OfflineRegion> result;
-
     while (query.run()) {
-        result.push_back(OfflineRegion(
-            query.get<int64_t>(0),
-            decodeOfflineRegionDefinition(query.get<std::string>(1)),
-            query.get<std::vector<uint8_t>>(2)));
+        const auto id = query.get<int64_t>(0);
+        const auto definition = query.get<std::string>(1);
+        const auto description = query.get<std::vector<uint8_t>>(2);
+        try {
+            OfflineRegion region(id, decodeOfflineRegionDefinition(definition), description);
+            result.emplace_back(std::move(region));
+        } catch (const std::exception& ex) {
+            // Catch errors from malformed offline region definitions
+            // and skip them.
+            Log::Error(Event::General, "%s", ex.what());
+        }
     }
-
     return result;
+} catch (const mapbox::sqlite::Exception& ex) {
+    handleError(ex, "list regions");
+    return {};
 }
 
-OfflineRegion OfflineDatabase::createRegion(const OfflineRegionDefinition& definition,
-                                            const OfflineRegionMetadata& metadata) {
+optional<OfflineRegion> OfflineDatabase::createRegion(const OfflineRegionDefinition& definition,
+                                                      const OfflineRegionMetadata& metadata) try {
     // clang-format off
     mapbox::sqlite::Query query{ getStatement(
         "INSERT INTO regions (definition, description) "
@@ -585,11 +625,13 @@ OfflineRegion OfflineDatabase::createRegion(const OfflineRegionDefinition& defin
     query.bind(1, encodeOfflineRegionDefinition(definition));
     query.bindBlob(2, metadata);
     query.run();
-
     return OfflineRegion(query.lastInsertRowId(), definition, metadata);
+} catch (const mapbox::sqlite::Exception& ex) {
+    handleError(ex, "create region");
+    return nullopt;
 }
 
-OfflineRegionMetadata OfflineDatabase::updateMetadata(const int64_t regionID, const OfflineRegionMetadata& metadata) {
+optional<OfflineRegionMetadata> OfflineDatabase::updateMetadata(const int64_t regionID, const OfflineRegionMetadata& metadata) try {
     // clang-format off
     mapbox::sqlite::Query query{ getStatement(
                                   "UPDATE regions SET description = ?1 "
@@ -600,9 +642,12 @@ OfflineRegionMetadata OfflineDatabase::updateMetadata(const int64_t regionID, co
     query.run();
 
     return metadata;
+} catch (const mapbox::sqlite::Exception& ex) {
+    handleError(ex, "update region metadata");
+    return nullopt;
 }
 
-void OfflineDatabase::deleteRegion(OfflineRegion&& region) {
+void OfflineDatabase::deleteRegion(OfflineRegion&& region) try {
     {
         mapbox::sqlite::Query query{ getStatement("DELETE FROM regions WHERE id = ?") };
         query.bind(1, region.getID());
@@ -610,13 +655,17 @@ void OfflineDatabase::deleteRegion(OfflineRegion&& region) {
     }
 
     evict(0);
+    assert(db);
     db->exec("PRAGMA incremental_vacuum");
 
     // Ensure that the cached offlineTileCount value is recalculated.
     offlineMapboxTileCount = {};
+} catch (const mapbox::sqlite::Exception& ex) {
+    handleError(ex, "delete region");
+    return;
 }
 
-optional<std::pair<Response, uint64_t>> OfflineDatabase::getRegionResource(int64_t regionID, const Resource& resource) {
+optional<std::pair<Response, uint64_t>> OfflineDatabase::getRegionResource(int64_t regionID, const Resource& resource) try {
     auto response = getInternal(resource);
 
     if (response) {
@@ -624,9 +673,12 @@ optional<std::pair<Response, uint64_t>> OfflineDatabase::getRegionResource(int64
     }
 
     return response;
+} catch (const mapbox::sqlite::Exception& ex) {
+    handleError(ex, "read region resource");
+    return nullopt;
 }
 
-optional<int64_t> OfflineDatabase::hasRegionResource(int64_t regionID, const Resource& resource) {
+optional<int64_t> OfflineDatabase::hasRegionResource(int64_t regionID, const Resource& resource) try {
     auto response = hasInternal(resource);
 
     if (response) {
@@ -634,29 +686,52 @@ optional<int64_t> OfflineDatabase::hasRegionResource(int64_t regionID, const Res
     }
 
     return response;
+} catch (const mapbox::sqlite::Exception& ex) {
+    handleError(ex, "query region resource");
+    return nullopt;
 }
 
-uint64_t OfflineDatabase::putRegionResource(int64_t regionID, const Resource& resource, const Response& response) {
+uint64_t OfflineDatabase::putRegionResource(int64_t regionID,
+                                            const Resource& resource,
+                                            const Response& response) try {
+    if (!db) {
+        initialize();
+    }
     mapbox::sqlite::Transaction transaction(*db);
     auto size = putRegionResourceInternal(regionID, resource, response);
     transaction.commit();
     return size;
+} catch (const mapbox::sqlite::Exception& ex) {
+    handleError(ex, "write region resource");
+    return 0;
 }
 
-void OfflineDatabase::putRegionResources(int64_t regionID, const std::list<std::tuple<Resource, Response>>& resources, OfflineRegionStatus& status) {
+void OfflineDatabase::putRegionResources(int64_t regionID,
+                                         const std::list<std::tuple<Resource, Response>>& resources,
+                                         OfflineRegionStatus& status) try {
+    if (!db) {
+        initialize();
+    }
     mapbox::sqlite::Transaction transaction(*db);
 
+    // Accumulate all statistics locally first before adding them to the OfflineRegionStatus object
+    // to ensure correctness when the transaction fails.
+    uint64_t completedResourceCount = 0;
+    uint64_t completedResourceSize = 0;
+    uint64_t completedTileCount = 0;
+    uint64_t completedTileSize = 0;
+
     for (const auto& elem : resources) {
         const auto& resource = std::get<0>(elem);
         const auto& response = std::get<1>(elem);
 
         try {
             uint64_t resourceSize = putRegionResourceInternal(regionID, resource, response);
-            status.completedResourceCount++;
-            status.completedResourceSize += resourceSize;
+            completedResourceCount++;
+            completedResourceSize += resourceSize;
             if (resource.kind == Resource::Kind::Tile) {
-                status.completedTileCount += 1;
-                status.completedTileSize += resourceSize;
+                completedTileCount += 1;
+                completedTileSize += resourceSize;
             }
         } catch (const MapboxTileLimitExceededException&) {
             // Commit the rest of the batch and retrow
@@ -667,6 +742,13 @@ void OfflineDatabase::putRegionResources(int64_t regionID, const std::list<std::
 
     // Commit the completed batch
     transaction.commit();
+
+    status.completedResourceCount += completedResourceCount;
+    status.completedResourceSize += completedResourceSize;
+    status.completedTileCount += completedTileCount;
+    status.completedTileSize += completedTileSize;
+} catch (const mapbox::sqlite::Exception& ex) {
+    handleError(ex, "write region resources");
 }
 
 uint64_t OfflineDatabase::putRegionResourceInternal(int64_t regionID, const Resource& resource, const Response& response) {
@@ -755,7 +837,7 @@ bool OfflineDatabase::markUsed(int64_t regionID, const Resource& resource) {
         mapbox::sqlite::Query selectQuery{ getStatement(
             "SELECT region_id "
             "FROM region_resources, resources "
-            "WHERE region_id    != ?1 "
+            "WHERE region_id    !=  ?1 "
             "  AND resources.url = ?2 "
             "LIMIT 1 ") };
         // clang-format on
@@ -766,15 +848,18 @@ bool OfflineDatabase::markUsed(int64_t regionID, const Resource& resource) {
     }
 }
 
-OfflineRegionDefinition OfflineDatabase::getRegionDefinition(int64_t regionID) {
+optional<OfflineRegionDefinition> OfflineDatabase::getRegionDefinition(int64_t regionID) try {
     mapbox::sqlite::Query query{ getStatement("SELECT definition FROM regions WHERE id = ?1") };
     query.bind(1, regionID);
     query.run();
 
     return decodeOfflineRegionDefinition(query.get<std::string>(0));
+} catch (const mapbox::sqlite::Exception& ex) {
+    handleError(ex, "load region");
+    return nullopt;
 }
 
-OfflineRegionStatus OfflineDatabase::getRegionCompletedStatus(int64_t regionID) {
+optional<OfflineRegionStatus> OfflineDatabase::getRegionCompletedStatus(int64_t regionID) try {
     OfflineRegionStatus result;
 
     std::tie(result.completedResourceCount, result.completedResourceSize)
@@ -786,6 +871,9 @@ OfflineRegionStatus OfflineDatabase::getRegionCompletedStatus(int64_t regionID)
     result.completedResourceSize += result.completedTileSize;
 
     return result;
+} catch (const mapbox::sqlite::Exception& ex) {
+    handleError(ex, "get region status");
+    return nullopt;
 }
 
 std::pair<int64_t, int64_t> OfflineDatabase::getCompletedResourceCountAndSize(int64_t regionID) {
@@ -920,7 +1008,7 @@ bool OfflineDatabase::offlineMapboxTileCountLimitExceeded() {
     return getOfflineMapboxTileCount() >= offlineMapboxTileCountLimit;
 }
 
-uint64_t OfflineDatabase::getOfflineMapboxTileCount() {
+uint64_t OfflineDatabase::getOfflineMapboxTileCount() try {
     // Calculating this on every call would be much simpler than caching and
     // manually updating the value, but it would make offline downloads an O(n²)
     // operation, because the database query below involves an index scan of
@@ -942,6 +1030,9 @@ uint64_t OfflineDatabase::getOfflineMapboxTileCount() {
 
     offlineMapboxTileCount = query.get<int64_t>(0);
     return *offlineMapboxTileCount;
+} catch (const mapbox::sqlite::Exception& ex) {
+    handleError(ex, "get offline Mapbox tile count");
+    return std::numeric_limits<uint64_t>::max();
 }
 
 bool OfflineDatabase::exceedsOfflineMapboxTileCountLimit(const Resource& resource) {
diff --git a/platform/default/mbgl/storage/offline_database.hpp b/platform/default/mbgl/storage/offline_database.hpp
index 38eb3783ba..cdad11b79e 100644
--- a/platform/default/mbgl/storage/offline_database.hpp
+++ b/platform/default/mbgl/storage/offline_database.hpp
@@ -18,6 +18,7 @@ namespace sqlite {
 class Database;
 class Statement;
 class Query;
+class Exception;
 } // namespace sqlite
 } // namespace mapbox
 
@@ -26,6 +27,10 @@ namespace mbgl {
 class Response;
 class TileID;
 
+namespace util {
+struct IOException;
+} // namespace util
+
 struct MapboxTileLimitExceededException :  util::Exception {
     MapboxTileLimitExceededException() : util::Exception("Mapbox tile limit exceeded") {}
 };
@@ -44,10 +49,10 @@ public:
 
     std::vector<OfflineRegion> listRegions();
 
-    OfflineRegion createRegion(const OfflineRegionDefinition&,
-                               const OfflineRegionMetadata&);
+    optional<OfflineRegion> createRegion(const OfflineRegionDefinition&,
+                                         const OfflineRegionMetadata&);
 
-    OfflineRegionMetadata updateMetadata(const int64_t regionID, const OfflineRegionMetadata&);
+    optional<OfflineRegionMetadata> updateMetadata(const int64_t regionID, const OfflineRegionMetadata&);
 
     void deleteRegion(OfflineRegion&&);
 
@@ -57,8 +62,8 @@ public:
     uint64_t putRegionResource(int64_t regionID, const Resource&, const Response&);
     void putRegionResources(int64_t regionID, const std::list<std::tuple<Resource, Response>>&, OfflineRegionStatus&);
 
-    OfflineRegionDefinition getRegionDefinition(int64_t regionID);
-    OfflineRegionStatus getRegionCompletedStatus(int64_t regionID);
+    optional<OfflineRegionDefinition> getRegionDefinition(int64_t regionID);
+    optional<OfflineRegionStatus> getRegionCompletedStatus(int64_t regionID);
 
     void setOfflineMapboxTileCountLimit(uint64_t);
     uint64_t getOfflineMapboxTileCountLimit();
@@ -67,12 +72,15 @@ public:
     bool exceedsOfflineMapboxTileCountLimit(const Resource&);
 
 private:
-    int userVersion();
-    void ensureSchema();
+    void initialize();
+    void handleError(const mapbox::sqlite::Exception&, const char* action);
+    void handleError(const util::IOException&, const char* action);
+
     void removeExisting();
     void removeOldCacheTable();
-    void migrateToVersion3();
+    void createSchema();
     void migrateToVersion5();
+    void migrateToVersion3();
     void migrateToVersion6();
 
     mapbox::sqlite::Statement& getStatement(const char *);
diff --git a/platform/default/mbgl/storage/offline_download.cpp b/platform/default/mbgl/storage/offline_download.cpp
index 4da51db655..179d2d5f57 100644
--- a/platform/default/mbgl/storage/offline_download.cpp
+++ b/platform/default/mbgl/storage/offline_download.cpp
@@ -62,39 +62,44 @@ OfflineRegionStatus OfflineDownload::getStatus() const {
         return status;
     }
 
-    OfflineRegionStatus result = offlineDatabase.getRegionCompletedStatus(id);
+    auto result = offlineDatabase.getRegionCompletedStatus(id);
+    if (!result) {
+        // We can't find this offline region because the database is unavailable, or the download
+        // does not exist.
+        return {};
+    }
 
-    result.requiredResourceCount++;
+    result->requiredResourceCount++;
     optional<Response> styleResponse = offlineDatabase.get(Resource::style(definition.styleURL));
     if (!styleResponse) {
-        return result;
+        return *result;
     }
 
     style::Parser parser;
     parser.parse(*styleResponse->data);
 
-    result.requiredResourceCountIsPrecise = true;
+    result->requiredResourceCountIsPrecise = true;
 
     for (const auto& source : parser.sources) {
         SourceType type = source->getType();
 
         auto handleTiledSource = [&] (const variant<std::string, Tileset>& urlOrTileset, const uint16_t tileSize) {
             if (urlOrTileset.is<Tileset>()) {
-                result.requiredResourceCount +=
+                result->requiredResourceCount +=
                     definition.tileCount(type, tileSize, urlOrTileset.get<Tileset>().zoomRange);
             } else {
-                result.requiredResourceCount += 1;
+                result->requiredResourceCount += 1;
                 const auto& url = urlOrTileset.get<std::string>();
                 optional<Response> sourceResponse = offlineDatabase.get(Resource::source(url));
                 if (sourceResponse) {
                     style::conversion::Error error;
                     optional<Tileset> tileset = style::conversion::convertJSON<Tileset>(*sourceResponse->data, error);
                     if (tileset) {
-                        result.requiredResourceCount +=
+                        result->requiredResourceCount +=
                             definition.tileCount(type, tileSize, (*tileset).zoomRange);
                     }
                 } else {
-                    result.requiredResourceCountIsPrecise = false;
+                    result->requiredResourceCountIsPrecise = false;
                 }
             }
         };
@@ -121,7 +126,7 @@ OfflineRegionStatus OfflineDownload::getStatus() const {
         case SourceType::GeoJSON: {
             const auto& geojsonSource = *source->as<GeoJSONSource>();
             if (geojsonSource.getURL()) {
-                result.requiredResourceCount += 1;
+                result->requiredResourceCount += 1;
             }
             break;
         }
@@ -129,7 +134,7 @@ OfflineRegionStatus OfflineDownload::getStatus() const {
         case SourceType::Image: {
             const auto& imageSource = *source->as<ImageSource>();
             if (imageSource.getURL()) {
-                result.requiredResourceCount += 1;
+                result->requiredResourceCount += 1;
             }
             break;
         }
@@ -142,14 +147,14 @@ OfflineRegionStatus OfflineDownload::getStatus() const {
     }
 
     if (!parser.glyphURL.empty()) {
-        result.requiredResourceCount += parser.fontStacks().size() * GLYPH_RANGES_PER_FONT_STACK;
+        result->requiredResourceCount += parser.fontStacks().size() * GLYPH_RANGES_PER_FONT_STACK;
     }
 
     if (!parser.spriteURL.empty()) {
-        result.requiredResourceCount += 2;
+        result->requiredResourceCount += 2;
     }
 
-    return result;
+    return *result;
 }
 
 void OfflineDownload::activateDownload() {
diff --git a/platform/default/sqlite3.cpp b/platform/default/sqlite3.cpp
index 1a6045a9a8..fed5a3a185 100644
--- a/platform/default/sqlite3.cpp
+++ b/platform/default/sqlite3.cpp
@@ -8,11 +8,38 @@
 #include <chrono>
 #include <experimental/optional>
 
+#include <mbgl/util/traits.hpp>
 #include <mbgl/util/logging.hpp>
 
 namespace mapbox {
 namespace sqlite {
 
+static_assert(mbgl::underlying_type(ResultCode::OK) == SQLITE_OK, "error");
+static_assert(mbgl::underlying_type(ResultCode::Error) == SQLITE_ERROR, "error");
+static_assert(mbgl::underlying_type(ResultCode::Internal) == SQLITE_INTERNAL, "error");
+static_assert(mbgl::underlying_type(ResultCode::Perm) == SQLITE_PERM, "error");
+static_assert(mbgl::underlying_type(ResultCode::Abort) == SQLITE_ABORT, "error");
+static_assert(mbgl::underlying_type(ResultCode::Busy) == SQLITE_BUSY, "error");
+static_assert(mbgl::underlying_type(ResultCode::Locked) == SQLITE_LOCKED, "error");
+static_assert(mbgl::underlying_type(ResultCode::NoMem) == SQLITE_NOMEM, "error");
+static_assert(mbgl::underlying_type(ResultCode::ReadOnly) == SQLITE_READONLY, "error");
+static_assert(mbgl::underlying_type(ResultCode::Interrupt) == SQLITE_INTERRUPT, "error");
+static_assert(mbgl::underlying_type(ResultCode::IOErr) == SQLITE_IOERR, "error");
+static_assert(mbgl::underlying_type(ResultCode::Corrupt) == SQLITE_CORRUPT, "error");
+static_assert(mbgl::underlying_type(ResultCode::NotFound) == SQLITE_NOTFOUND, "error");
+static_assert(mbgl::underlying_type(ResultCode::Full) == SQLITE_FULL, "error");
+static_assert(mbgl::underlying_type(ResultCode::CantOpen) == SQLITE_CANTOPEN, "error");
+static_assert(mbgl::underlying_type(ResultCode::Protocol) == SQLITE_PROTOCOL, "error");
+static_assert(mbgl::underlying_type(ResultCode::Schema) == SQLITE_SCHEMA, "error");
+static_assert(mbgl::underlying_type(ResultCode::TooBig) == SQLITE_TOOBIG, "error");
+static_assert(mbgl::underlying_type(ResultCode::Constraint) == SQLITE_CONSTRAINT, "error");
+static_assert(mbgl::underlying_type(ResultCode::Mismatch) == SQLITE_MISMATCH, "error");
+static_assert(mbgl::underlying_type(ResultCode::Misuse) == SQLITE_MISUSE, "error");
+static_assert(mbgl::underlying_type(ResultCode::NoLFS) == SQLITE_NOLFS, "error");
+static_assert(mbgl::underlying_type(ResultCode::Auth) == SQLITE_AUTH, "error");
+static_assert(mbgl::underlying_type(ResultCode::Range) == SQLITE_RANGE, "error");
+static_assert(mbgl::underlying_type(ResultCode::NotADB) == SQLITE_NOTADB, "error");
+
 class DatabaseImpl {
 public:
     DatabaseImpl(sqlite3* db_)
@@ -24,7 +51,7 @@ public:
     {
         const int error = sqlite3_close(db);
         if (error != SQLITE_OK) {
-            mbgl::Log::Error(mbgl::Event::Database, "%s (Code %i)", sqlite3_errmsg(db), error);
+            mbgl::Log::Error(mbgl::Event::Database, error, "Failed to close database: %s", sqlite3_errmsg(db));
         }
     }
 
@@ -66,11 +93,8 @@ public:
 template <typename T>
 using optional = std::experimental::optional<T>;
 
-static void errorLogCallback(void *, const int err, const char *msg) {
-    mbgl::Log::Record(mbgl::EventSeverity::Info, mbgl::Event::Database, err, "%s", msg);
-}
-
-const static bool sqliteVersionCheck __attribute__((unused)) = []() {
+__attribute__((constructor))
+static void initalize() {
     if (sqlite3_libversion_number() / 1000000 != SQLITE_VERSION_NUMBER / 1000000) {
         char message[96];
         snprintf(message, 96,
@@ -79,15 +103,17 @@ const static bool sqliteVersionCheck __attribute__((unused)) = []() {
         throw std::runtime_error(message);
     }
 
+#ifndef NDEBUG
     // Enable SQLite logging before initializing the database.
-    sqlite3_config(SQLITE_CONFIG_LOG, errorLogCallback, nullptr);
-
-    return true;
-}();
+    sqlite3_config(SQLITE_CONFIG_LOG, [](void *, const int err, const char *msg) {
+        mbgl::Log::Record(mbgl::EventSeverity::Debug, mbgl::Event::Database, err, "%s", msg);
+    }, nullptr);
+#endif
+}
 
 mapbox::util::variant<Database, Exception> Database::tryOpen(const std::string &filename, int flags) {
     sqlite3* db = nullptr;
-    const int error = sqlite3_open_v2(filename.c_str(), &db, flags, nullptr);
+    const int error = sqlite3_open_v2(filename.c_str(), &db, flags | SQLITE_OPEN_URI, nullptr);
     if (error != SQLITE_OK) {
         const auto message = sqlite3_errmsg(db);
         return Exception { error, message };
diff --git a/platform/qt/src/sqlite3.cpp b/platform/qt/src/sqlite3.cpp
index 2ca09fd3ad..96cee5fff8 100644
--- a/platform/qt/src/sqlite3.cpp
+++ b/platform/qt/src/sqlite3.cpp
@@ -23,13 +23,6 @@
 namespace mapbox {
 namespace sqlite {
 
-// https://www.sqlite.org/rescode.html#ok
-static_assert(mbgl::underlying_type(ResultCode::OK) == 0, "error");
-// https://www.sqlite.org/rescode.html#cantopen
-static_assert(mbgl::underlying_type(ResultCode::CantOpen) == 14, "error");
-// https://www.sqlite.org/rescode.html#notadb
-static_assert(mbgl::underlying_type(ResultCode::NotADB) == 26, "error");
-
 void checkQueryError(const QSqlQuery& query) {
     QSqlError lastError = query.lastError();
     if (lastError.type() != QSqlError::NoError) {
@@ -114,6 +107,11 @@ mapbox::util::variant<Database, Exception> Database::tryOpen(const std::string &
         connectOptions.append("QSQLITE_OPEN_READONLY");
     }
 
+    if (filename.compare(0, 5, "file:") == 0) {
+        if (!connectOptions.isEmpty()) connectOptions.append(';');
+        connectOptions.append("QSQLITE_OPEN_URI");
+    }
+
     db.setConnectOptions(connectOptions);
     db.setDatabaseName(QString(filename.c_str()));
 
diff --git a/test/fixtures/offline_database/corrupt-delayed.db b/test/fixtures/offline_database/corrupt-delayed.db
new file mode 100644
index 0000000000..04989dbf36
--- /dev/null
+++ b/test/fixtures/offline_database/corrupt-delayed.db
diff --git a/test/fixtures/offline_database/corrupt-immediate.db b/test/fixtures/offline_database/corrupt-immediate.db
new file mode 100644
index 0000000000..8909c402b2
--- /dev/null
+++ b/test/fixtures/offline_database/corrupt-immediate.db
diff --git a/test/src/mbgl/test/fixture_log_observer.cpp b/test/src/mbgl/test/fixture_log_observer.cpp
index d8a4b9edce..d768c0284a 100644
--- a/test/src/mbgl/test/fixture_log_observer.cpp
+++ b/test/src/mbgl/test/fixture_log_observer.cpp
@@ -32,7 +32,9 @@ bool FixtureLog::Observer::onRecord(EventSeverity severity,
                                     const std::string& msg) {
     std::lock_guard<std::mutex> lock(messagesMutex);
 
-    messages.emplace_back(severity, event, code, msg);
+    if (severity != EventSeverity::Debug) {
+        messages.emplace_back(severity, event, code, msg);
+    }
 
     return true;
 }
@@ -48,7 +50,7 @@ size_t FixtureLog::Observer::count(const Message& message, bool substring) const
 
     size_t message_count = 0;
     for (const auto& msg : messages) {
-        if (msg.matches(message, substring)) {
+        if (!msg.checked && msg.matches(message, substring)) {
             message_count++;
             msg.checked = true;
         }
diff --git a/test/src/mbgl/test/sqlite3_test_fs.cpp b/test/src/mbgl/test/sqlite3_test_fs.cpp
new file mode 100644
index 0000000000..16d411faff
--- /dev/null
+++ b/test/src/mbgl/test/sqlite3_test_fs.cpp
@@ -0,0 +1,320 @@
+#ifndef __QT__ // Qt doesn't expose SQLite VFS
+
+#include <mbgl/test/sqlite3_test_fs.hpp>
+
+#include <sqlite3.h>
+
+#include <stdexcept>
+#include <cstdio>
+#include <cstring>
+#include <cstdlib>
+#include <cassert>
+
+static bool sqlite3_test_fs_debug = false;
+static bool sqlite3_test_fs_io = true;
+static bool sqlite3_test_fs_file_open = true;
+static bool sqlite3_test_fs_file_create = true;
+static int64_t sqlite3_test_fs_read_limit = -1;
+static int64_t sqlite3_test_fs_write_limit = -1;
+
+struct File {
+    sqlite3_file base;
+    sqlite3_file* real;
+};
+
+static int sqlite3_test_fs_close(sqlite3_file* pFile) {
+    if (sqlite3_test_fs_debug) {
+        fprintf(stderr, "SQLite3: close(%p)\n", pFile);
+    }
+    if (!sqlite3_test_fs_io) {
+        return SQLITE_AUTH;
+    }
+    File* file = (File*)pFile;
+    const int rc = file->real->pMethods->xClose(file->real);
+    if (rc == SQLITE_OK) {
+        sqlite3_free((void*)file->base.pMethods);
+        file->base.pMethods = 0;
+    }
+    return rc;
+}
+
+static int sqlite3_test_fs_read(sqlite3_file* pFile, void* zBuf, int iAmt, sqlite3_int64 iOfst) {
+    if (sqlite3_test_fs_debug) {
+        fprintf(stderr, "SQLite3: read(%p, amount=%d, offset=%lld)\n", pFile, iAmt, iOfst);
+    }
+    if (!sqlite3_test_fs_io) {
+        return SQLITE_AUTH;
+    }
+    if (sqlite3_test_fs_read_limit >= 0) {
+        if (iAmt > sqlite3_test_fs_read_limit) {
+            iAmt = 0;
+            return SQLITE_IOERR;
+        }
+        sqlite3_test_fs_read_limit -= iAmt;
+    }
+    File* file = (File*)pFile;
+    return file->real->pMethods->xRead(file->real, zBuf, iAmt, iOfst);
+}
+
+static int sqlite3_test_fs_write(sqlite3_file* pFile, const void* zBuf, int iAmt, sqlite3_int64 iOfst) {
+    if (sqlite3_test_fs_debug) {
+        fprintf(stderr, "SQLite3: write(%p, amount=%d, offset=%lld)\n", pFile, iAmt, iOfst);
+    }
+    if (!sqlite3_test_fs_io) {
+        return SQLITE_AUTH;
+    }
+    if (sqlite3_test_fs_write_limit >= 0) {
+        if (iAmt > sqlite3_test_fs_write_limit) {
+            iAmt = 0;
+            return SQLITE_FULL;
+        }
+        sqlite3_test_fs_write_limit -= iAmt;
+    }
+    File* file = (File*)pFile;
+    return file->real->pMethods->xWrite(file->real, zBuf, iAmt, iOfst);
+}
+
+static int sqlite3_test_fs_truncate(sqlite3_file* pFile, sqlite3_int64 size) {
+    if (sqlite3_test_fs_debug) {
+        fprintf(stderr, "SQLite3: truncate(%p, size=%lld)\n", pFile, size);
+    }
+    if (!sqlite3_test_fs_io) {
+        return SQLITE_AUTH;
+    }
+    File* file = (File*)pFile;
+    return file->real->pMethods->xTruncate(file->real, size);
+}
+
+static int sqlite3_test_fs_sync(sqlite3_file* pFile, int flags) {
+    if (sqlite3_test_fs_debug) {
+        fprintf(stderr, "SQLite3: sync(%p, flags=%d)\n", pFile, flags);
+    }
+    if (!sqlite3_test_fs_io) {
+        return SQLITE_AUTH;
+    }
+    File* file = (File*)pFile;
+    return file->real->pMethods->xSync(file->real, flags);
+}
+
+static int sqlite3_test_fs_file_size(sqlite3_file* pFile, sqlite3_int64* pSize) {
+    if (sqlite3_test_fs_debug) {
+        fprintf(stderr, "SQLite3: file_size(%p)\n", pFile);
+    }
+    if (!sqlite3_test_fs_io) {
+        return SQLITE_AUTH;
+    }
+    File* file = (File*)pFile;
+    return file->real->pMethods->xFileSize(file->real, pSize);
+}
+
+static int sqlite3_test_fs_lock(sqlite3_file* pFile, int eLock) {
+    if (sqlite3_test_fs_debug) {
+        fprintf(stderr, "SQLite3: lock(%p, %d)\n", pFile, eLock);
+    }
+    File* file = (File*)pFile;
+    return file->real->pMethods->xLock(file->real, eLock);
+}
+
+static int sqlite3_test_fs_unlock(sqlite3_file* pFile, int eLock) {
+    if (sqlite3_test_fs_debug) {
+        fprintf(stderr, "SQLite3: unlock(%p, %d)\n", pFile, eLock);
+    }
+    File* file = (File*)pFile;
+    return file->real->pMethods->xUnlock(file->real, eLock);
+}
+
+static int sqlite3_test_fs_check_reserved_lock(sqlite3_file* pFile, int* pResOut) {
+    if (sqlite3_test_fs_debug) {
+        fprintf(stderr, "SQLite3: check_reserved_lock(%p)\n", pFile);
+    }
+    File* file = (File*)pFile;
+    return file->real->pMethods->xCheckReservedLock(file->real, pResOut);
+}
+
+static int sqlite3_test_fs_file_control(sqlite3_file* pFile, int op, void* pArg) {
+    if (sqlite3_test_fs_debug) {
+        fprintf(stderr, "SQLite3: file_control(%p, op=%d)\n", pFile, op);
+    }
+    if (!sqlite3_test_fs_io) {
+        return SQLITE_AUTH;
+    }
+    File* file = (File*)pFile;
+    return file->real->pMethods->xFileControl(file->real, op, pArg);
+}
+
+static int sqlite3_test_fs_sector_size(sqlite3_file* pFile) {
+    if (sqlite3_test_fs_debug) {
+        fprintf(stderr, "SQLite3: sector_size(%p)\n", pFile);
+    }
+    if (!sqlite3_test_fs_io) {
+        return SQLITE_AUTH;
+    }
+    File* file = (File*)pFile;
+    return file->real->pMethods->xSectorSize(file->real);
+}
+
+static int sqlite3_test_fs_device_characteristics(sqlite3_file* pFile) {
+    if (sqlite3_test_fs_debug) {
+        fprintf(stderr, "SQLite3: device_characteristics(%p)\n", pFile);
+    }
+    if (!sqlite3_test_fs_io) {
+        return SQLITE_AUTH;
+    }
+    File* file = (File*)pFile;
+    return file->real->pMethods->xDeviceCharacteristics(file->real);
+}
+
+static int sqlite3_test_fs_open(sqlite3_vfs* vfs, const char* zName, sqlite3_file* pFile, int flags, int* pOutFlags) {
+    if (sqlite3_test_fs_debug) {
+        fprintf(stderr, "SQLite3: open(name=%s, flags=%d) -> %p\n", zName, flags, pFile);
+    }
+    if (!sqlite3_test_fs_io) {
+        pFile->pMethods = NULL;
+        return SQLITE_AUTH;
+    }
+    if (!sqlite3_test_fs_file_open) {
+        pFile->pMethods = NULL;
+        return SQLITE_CANTOPEN;
+    }
+
+    File* file = (File*)pFile;
+    sqlite3_vfs* unix_fs = (sqlite3_vfs*)vfs->pAppData;
+    file->real = (sqlite3_file*)&file[1];
+
+    if (!sqlite3_test_fs_file_create) {
+        int res;
+        const int result = unix_fs->xAccess(vfs, zName, SQLITE_ACCESS_EXISTS, &res);
+        if (result != SQLITE_OK) {
+            pFile->pMethods = NULL;
+            return result;
+        }
+        if (res != 1) {
+            pFile->pMethods = NULL;
+            return SQLITE_CANTOPEN;
+        }
+    }
+
+    const int status = unix_fs->xOpen(unix_fs, zName, file->real, flags, pOutFlags);
+    if (file->real->pMethods) {
+        sqlite3_io_methods* methods = (sqlite3_io_methods*)sqlite3_malloc(sizeof(sqlite3_io_methods));
+        memset(methods, 0, sizeof(sqlite3_io_methods));
+        methods->iVersion = 1;
+        methods->xClose = sqlite3_test_fs_close;
+        methods->xRead = sqlite3_test_fs_read;
+        methods->xWrite = sqlite3_test_fs_write;
+        methods->xTruncate = sqlite3_test_fs_truncate;
+        methods->xSync = sqlite3_test_fs_sync;
+        methods->xFileSize = sqlite3_test_fs_file_size;
+        methods->xLock = sqlite3_test_fs_lock;
+        methods->xUnlock = sqlite3_test_fs_unlock;
+        methods->xCheckReservedLock = sqlite3_test_fs_check_reserved_lock;
+        methods->xFileControl = sqlite3_test_fs_file_control;
+        methods->xSectorSize = sqlite3_test_fs_sector_size;
+        methods->xDeviceCharacteristics = sqlite3_test_fs_device_characteristics;
+        pFile->pMethods = methods;
+    }
+    return status;
+}
+
+static int sqlite3_test_fs_delete(sqlite3_vfs* vfs, const char *zPath, int dirSync) {
+    if (sqlite3_test_fs_debug) {
+        fprintf(stderr, "SQLite3: delete(name=%s, sync=%d)\n", zPath, dirSync);
+    }
+    if (!sqlite3_test_fs_io) {
+        return SQLITE_AUTH;
+    }
+    sqlite3_vfs* unix_fs = (sqlite3_vfs*)vfs->pAppData;
+    return unix_fs->xDelete(unix_fs, zPath, dirSync);
+}
+
+static int sqlite3_test_fs_access(sqlite3_vfs* vfs, const char *zPath, int flags, int *pResOut) {
+    if (sqlite3_test_fs_debug) {
+        fprintf(stderr, "SQLite3: access(name=%s, flags=%d)\n", zPath, flags);
+    }
+    if (!sqlite3_test_fs_io) {
+        return SQLITE_AUTH;
+    }
+    sqlite3_vfs* unix_fs = (sqlite3_vfs*)vfs->pAppData;
+    return unix_fs->xAccess(unix_fs, zPath, flags, pResOut);
+}
+
+namespace mbgl {
+namespace test {
+
+SQLite3TestFS::SQLite3TestFS() {
+    sqlite3_vfs* unix_fs = sqlite3_vfs_find("unix");
+    if (unix_fs == 0) {
+        abort();
+    }
+
+    sqlite3_vfs* test_fs = (sqlite3_vfs*)sqlite3_malloc(sizeof(sqlite3_vfs));
+    if (test_fs == 0) {
+        abort();
+    }
+    memset(test_fs, 0, sizeof(sqlite3_vfs));
+    test_fs->iVersion = 1;
+    test_fs->szOsFile = unix_fs->szOsFile + sizeof(File);
+    test_fs->mxPathname = unix_fs->mxPathname;
+    test_fs->zName = "test_fs";
+    test_fs->pAppData = unix_fs;
+    test_fs->xOpen = sqlite3_test_fs_open;
+    test_fs->xDelete = sqlite3_test_fs_delete;
+    test_fs->xAccess = sqlite3_test_fs_access;
+    test_fs->xFullPathname = unix_fs->xFullPathname;
+    test_fs->xDlOpen = unix_fs->xDlOpen;
+    test_fs->xDlError = unix_fs->xDlError;
+    test_fs->xDlSym = unix_fs->xDlSym;
+    test_fs->xDlClose = unix_fs->xDlClose;
+    test_fs->xRandomness = unix_fs->xRandomness;
+    test_fs->xSleep = unix_fs->xSleep;
+    test_fs->xCurrentTime = unix_fs->xCurrentTime;
+    test_fs->xGetLastError = unix_fs->xGetLastError;
+
+    sqlite3_vfs_register(test_fs, 0);
+}
+
+SQLite3TestFS::~SQLite3TestFS() {
+    reset();
+    sqlite3_vfs* test_fs = sqlite3_vfs_find("test_fs");
+    if (test_fs) {
+        sqlite3_vfs_unregister(test_fs);
+    }
+}
+
+void SQLite3TestFS::setDebug(bool value) {
+    sqlite3_test_fs_debug = value;
+}
+
+void SQLite3TestFS::allowIO(bool value) {
+    sqlite3_test_fs_io = value;
+}
+
+void SQLite3TestFS::allowFileOpen(bool value) {
+    sqlite3_test_fs_file_open = value;
+}
+
+void SQLite3TestFS::allowFileCreate(bool value) {
+    sqlite3_test_fs_file_create = value;
+}
+
+void SQLite3TestFS::setReadLimit(int64_t value) {
+    sqlite3_test_fs_read_limit = value;
+}
+
+void SQLite3TestFS::setWriteLimit(int64_t value) {
+    sqlite3_test_fs_write_limit = value;
+}
+
+void SQLite3TestFS::reset() {
+    setDebug(false);
+    allowIO(true);
+    allowFileOpen(true);
+    allowFileCreate(true);
+    setReadLimit(-1);
+    setWriteLimit(-1);
+}
+
+} // namespace test
+} // namespace mbgl
+
+#endif // __QT__
diff --git a/test/src/mbgl/test/sqlite3_test_fs.hpp b/test/src/mbgl/test/sqlite3_test_fs.hpp
new file mode 100644
index 0000000000..00351f49ac
--- /dev/null
+++ b/test/src/mbgl/test/sqlite3_test_fs.hpp
@@ -0,0 +1,39 @@
+#pragma once
+
+#include <cstdint>
+
+namespace mbgl {
+namespace test {
+
+class SQLite3TestFS {
+public:
+    SQLite3TestFS();
+    ~SQLite3TestFS();
+
+    // When enabled, the VFS will log all I/O operations to stdout.
+    void setDebug(bool);
+
+    // Allow any type of I/O. Will fail with SQLITE_AUTH if set to false. This is useful to simulate
+    // scenarios where the OS blocks an entire app's I/O, e.g. when it's in the background.
+    void allowIO(bool);
+    
+    // Allow files to be opened. Will fail with SQLITE_CANTOPEN if set to false.
+    void allowFileOpen(bool);
+    
+    // Allow files to be created. Will fail with SQLITE_CANTOPEN if set to false.
+    void allowFileCreate(bool);
+    
+    // Allow N bytes to be read, then fail reads with SQLITE_IOERR. -1 == unlimited
+    // This limit is global, not per file.
+    void setReadLimit(int64_t);
+    
+    // Allow N bytes to be written, then fail writes with SQLITE_FULL. -1 == unlimited
+    // This limit is global, not per file.
+    void setWriteLimit(int64_t);
+    
+    // Reset all restrictions.
+    void reset();
+};
+
+} // namespace test
+} // namespace mbgl
diff --git a/test/storage/offline_database.test.cpp b/test/storage/offline_database.test.cpp
index 000f24e1cd..de40d8caf7 100644
--- a/test/storage/offline_database.test.cpp
+++ b/test/storage/offline_database.test.cpp
@@ -1,5 +1,6 @@
 #include <mbgl/test/util.hpp>
 #include <mbgl/test/fixture_log_observer.hpp>
+#include <mbgl/test/sqlite3_test_fs.hpp>
 
 #include <mbgl/storage/offline_database.hpp>
 #include <mbgl/storage/resource.hpp>
@@ -13,51 +14,235 @@
 
 using namespace std::literals::string_literals;
 using namespace mbgl;
+using mapbox::sqlite::ResultCode;
 
 static constexpr const char* filename = "test/fixtures/offline_database/offline.db";
+#ifndef __QT__ // Qt doesn't expose the ability to register virtual file system handlers.
+static constexpr const char* filename_test_fs = "file:test/fixtures/offline_database/offline.db?vfs=test_fs";
+#endif
 
-TEST(OfflineDatabase, TEST_REQUIRES_WRITE(Create)) {
-    FixtureLog log;
+static void deleteDatabaseFiles() {
+    // Delete leftover journaling files as well.
     util::deleteFile(filename);
+    util::deleteFile(filename + "-wal"s);
+    util::deleteFile(filename + "-journal"s);
+}
+
+static FixtureLog::Message error(ResultCode code, const char* message) {
+    return { EventSeverity::Error, Event::Database, static_cast<int64_t>(code), message };
+}
+
+static FixtureLog::Message warning(ResultCode code, const char* message) {
+    return { EventSeverity::Warning, Event::Database, static_cast<int64_t>(code), message };
+}
+
+static int databasePageCount(const std::string& path) {
+    mapbox::sqlite::Database db = mapbox::sqlite::Database::open(path, mapbox::sqlite::ReadOnly);
+    mapbox::sqlite::Statement stmt{ db, "pragma page_count" };
+    mapbox::sqlite::Query query{ stmt };
+    query.run();
+    return query.get<int>(0);
+}
+
+static int databaseUserVersion(const std::string& path) {
+    mapbox::sqlite::Database db = mapbox::sqlite::Database::open(path, mapbox::sqlite::ReadOnly);
+    mapbox::sqlite::Statement stmt{ db, "pragma user_version" };
+    mapbox::sqlite::Query query{ stmt };
+    query.run();
+    return query.get<int>(0);
+}
+
+static std::string databaseJournalMode(const std::string& path) {
+    mapbox::sqlite::Database db = mapbox::sqlite::Database::open(path, mapbox::sqlite::ReadOnly);
+    mapbox::sqlite::Statement stmt{ db, "pragma journal_mode" };
+    mapbox::sqlite::Query query{ stmt };
+    query.run();
+    return query.get<std::string>(0);
+}
 
+static int databaseSyncMode(const std::string& path) {
+    mapbox::sqlite::Database db = mapbox::sqlite::Database::open(path, mapbox::sqlite::ReadOnly);
+    mapbox::sqlite::Statement stmt{ db, "pragma synchronous" };
+    mapbox::sqlite::Query query{ stmt };
+    query.run();
+    return query.get<int>(0);
+}
+
+static std::vector<std::string> databaseTableColumns(const std::string& path, const std::string& name) {
+    mapbox::sqlite::Database db = mapbox::sqlite::Database::open(path, mapbox::sqlite::ReadOnly);
+    const auto sql = std::string("pragma table_info(") + name + ")";
+    mapbox::sqlite::Statement stmt{ db, sql.c_str() };
+    mapbox::sqlite::Query query{ stmt };
+    std::vector<std::string> columns;
+    while (query.run()) {
+        columns.push_back(query.get<std::string>(1));
+    }
+    return columns;
+}
+
+namespace fixture {
+
+const Resource resource{ Resource::Style, "mapbox://test" };
+const Resource tile = Resource::tile("mapbox://test", 1, 0, 0, 0, Tileset::Scheme::XYZ);
+const Response response = [] {
+    Response res;
+    res.data = std::make_shared<std::string>("first");
+    return res;
+}();
+
+} // namespace
+
+TEST(OfflineDatabase, TEST_REQUIRES_WRITE(Create)) {
+    FixtureLog log;
+    deleteDatabaseFiles();
     OfflineDatabase db(filename);
     EXPECT_FALSE(bool(db.get({ Resource::Unknown, "mapbox://test" })));
 
     EXPECT_EQ(0u, log.uncheckedCount());
 }
 
+#ifndef __QT__ // Qt doesn't expose the ability to register virtual file system handlers.
+TEST(OfflineDatabase, TEST_REQUIRES_WRITE(CreateFail)) {
+    FixtureLog log;
+    deleteDatabaseFiles();
+    test::SQLite3TestFS fs;
+
+    // Opening the database will fail because our mock VFS returns a SQLITE_CANTOPEN error because
+    // it is not allowed to create the file. The OfflineDatabase object should handle this gracefully
+    // and treat it like an empty cache that can't be written to.
+    fs.allowFileCreate(false);
+    OfflineDatabase db(filename_test_fs);
+    EXPECT_EQ(1u, log.count(warning(ResultCode::CantOpen, "Can't open database: unable to open database file")));
+
+    EXPECT_EQ(0u, log.uncheckedCount());
+
+    // We can try to insert things into the cache, but since the cache database isn't open, it won't be stored.
+    for (const auto& res : { fixture::resource, fixture::tile }) {
+        EXPECT_EQ(std::make_pair(false, uint64_t(0)), db.put(res, fixture::response));
+        EXPECT_EQ(1u, log.count(warning(ResultCode::CantOpen, "Can't write resource: unable to open database file")));
+        EXPECT_EQ(0u, log.uncheckedCount());
+    }
+
+    // We can also still "query" the database even though it is not open, and we will always get an empty result.
+    for (const auto& res : { fixture::resource, fixture::tile }) {
+        EXPECT_FALSE(bool(db.get(res)));
+        EXPECT_EQ(1u, log.count(warning(ResultCode::CantOpen, "Can't update timestamp: unable to open database file")));
+        EXPECT_EQ(1u, log.count(warning(ResultCode::CantOpen, "Can't read resource: unable to open database file")));
+        EXPECT_EQ(0u, log.uncheckedCount());
+    }
+
+    // Now, we're "freeing up" some space on the disk, and try to insert and query again. This time, we should
+    // be opening the datbase, creating the schema, and writing the data so that we can retrieve it again.
+    fs.allowFileCreate(true);
+    for (const auto& res : { fixture::resource, fixture::tile }) {
+        EXPECT_EQ(std::make_pair(true, uint64_t(5)), db.put(res, fixture::response));
+        auto result = db.get(res);
+        EXPECT_EQ(0u, log.uncheckedCount());
+        ASSERT_TRUE(result && result->data);
+        EXPECT_EQ("first", *result->data);
+    }
+
+    // Next, set the file system to read only mode and try to read the data again. While we can't
+    // write anymore, we should still be able to read, and the query that tries to update the last
+    // accessed timestamp may fail without crashing.
+    fs.allowFileCreate(false);
+    fs.setWriteLimit(0);
+    for (const auto& res : { fixture::resource, fixture::tile }) {
+        auto result = db.get(res);
+        EXPECT_EQ(1u, log.count(warning(ResultCode::CantOpen, "Can't update timestamp: unable to open database file")));
+        EXPECT_EQ(0u, log.uncheckedCount());
+
+        ASSERT_TRUE(result && result->data);
+        EXPECT_EQ("first", *result->data);
+    }
+    fs.setDebug(false);
+
+    // We're allowing SQLite to create a journal file, but restrict the number of bytes it
+    // can write so that it can start writing the journal file, but eventually fails during the
+    // timestamp update.
+    fs.allowFileCreate(true);
+    fs.setWriteLimit(8192);
+    for (const auto& res : { fixture::resource, fixture::tile }) {
+        auto result = db.get(res);
+        EXPECT_EQ(1u, log.count(warning(ResultCode::Full, "Can't update timestamp: database or disk is full")));
+        EXPECT_EQ(0u, log.uncheckedCount());
+        ASSERT_TRUE(result && result->data);
+        EXPECT_EQ("first", *result->data);
+    }
+
+    // Lastly, we're disabling all I/O to simulate a backgrounded app that is restricted from doing
+    // any disk I/O at all.
+    fs.setWriteLimit(-1);
+    fs.allowIO(false);
+    for (const auto& res : { fixture::resource, fixture::tile }) {
+        // First, try reading.
+        auto result = db.get(res);
+        EXPECT_EQ(1u, log.count(warning(ResultCode::Auth, "Can't update timestamp: authorization denied")));
+        EXPECT_EQ(1u, log.count(warning(ResultCode::Auth, "Can't read resource: authorization denied")));
+        EXPECT_EQ(0u, log.uncheckedCount());
+        EXPECT_FALSE(result);
+
+        // Now try inserting.
+        EXPECT_EQ(std::make_pair(false, uint64_t(0)), db.put(res, fixture::response));
+        EXPECT_EQ(1u, log.count(warning(ResultCode::Auth, "Can't write resource: authorization denied")));
+        EXPECT_EQ(0u, log.uncheckedCount());
+    }
+
+    // Allow deleting the database.
+    fs.reset();
+}
+#endif // __QT__
+
 TEST(OfflineDatabase, TEST_REQUIRES_WRITE(SchemaVersion)) {
     FixtureLog log;
-    util::deleteFile(filename);
+    deleteDatabaseFiles();
 
     {
         mapbox::sqlite::Database db = mapbox::sqlite::Database::open(filename, mapbox::sqlite::ReadWriteCreate);
+        db.setBusyTimeout(Milliseconds(1000));
         db.exec("PRAGMA user_version = 1");
     }
 
+    {
+        OfflineDatabase db(filename);
+    }
+
+    EXPECT_EQ(6, databaseUserVersion(filename));
+
     OfflineDatabase db(filename);
+    // Now try inserting and reading back to make sure we have a valid database.
+    for (const auto& res : { fixture::resource, fixture::tile }) {
+        EXPECT_EQ(std::make_pair(true, uint64_t(5)), db.put(res, fixture::response));
+        EXPECT_EQ(0u, log.uncheckedCount());
+        auto result = db.get(res);
+        EXPECT_EQ(0u, log.uncheckedCount());
+        ASSERT_TRUE(result && result->data);
+        EXPECT_EQ("first", *result->data);
+    }
 
     EXPECT_EQ(0u, log.uncheckedCount());
 }
 
 TEST(OfflineDatabase, TEST_REQUIRES_WRITE(Invalid)) {
     FixtureLog log;
-    util::deleteFile(filename);
+    deleteDatabaseFiles();
     util::write_file(filename, "this is an invalid file");
 
     OfflineDatabase db(filename);
-
-#ifndef __QT__
-    // Only non-Qt platforms are setting a logger on the SQLite object.
     // Checking two possibilities for the error string because it apparently changes between SQLite versions.
-    EXPECT_EQ(1u,
-        log.count({ EventSeverity::Info, Event::Database, static_cast<int64_t>(mapbox::sqlite::ResultCode::NotADB),
-            "statement aborts at 1: [PRAGMA user_version] file is encrypted or is not a database" }, true) +
-        log.count({ EventSeverity::Info, Event::Database, static_cast<int64_t>(mapbox::sqlite::ResultCode::NotADB),
-            "statement aborts at 1: [PRAGMA user_version] file is not a database" }, true));
-#endif
-    EXPECT_EQ(1u, log.count({ EventSeverity::Warning, Event::Database, -1, "Removing existing incompatible offline database" }));
-    EXPECT_EQ(0u, log.uncheckedCount());
+    EXPECT_EQ(1u, log.count(error(ResultCode::NotADB, "Can't open database: file is encrypted or is not a database"), true) +
+                  log.count(error(ResultCode::NotADB, "Can't open database: file is not a database"), true));
+    EXPECT_EQ(1u, log.count(warning(static_cast<ResultCode>(-1), "Removing existing incompatible offline database")));
+
+    // Now try inserting and reading back to make sure we have a valid database.
+    for (const auto& res : { fixture::resource, fixture::tile }) {
+        EXPECT_EQ(std::make_pair(true, uint64_t(5)), db.put(res, fixture::response));
+        EXPECT_EQ(0u, log.uncheckedCount());
+        auto result = db.get(res);
+        EXPECT_EQ(0u, log.uncheckedCount());
+        ASSERT_TRUE(result && result->data);
+        EXPECT_EQ("first", *result->data);
+    }
 }
 
 TEST(OfflineDatabase, PutDoesNotStoreConnectionErrors) {
@@ -118,7 +303,7 @@ TEST(OfflineDatabase, PutResource) {
 
 TEST(OfflineDatabase, TEST_REQUIRES_WRITE(GetResourceFromOfflineRegion)) {
     FixtureLog log;
-    util::deleteFile(filename);
+    deleteDatabaseFiles();
     util::copyFile(filename, "test/fixtures/offline_database/satellite_test.db");
 
     OfflineDatabase db(filename, mapbox::sqlite::ReadOnly);
@@ -228,14 +413,15 @@ TEST(OfflineDatabase, CreateRegion) {
     OfflineDatabase db(":memory:");
     OfflineRegionDefinition definition { "http://example.com/style", LatLngBounds::hull({1, 2}, {3, 4}), 5, 6, 2.0 };
     OfflineRegionMetadata metadata {{ 1, 2, 3 }};
-    OfflineRegion region = db.createRegion(definition, metadata);
+    auto region = db.createRegion(definition, metadata);
+    ASSERT_TRUE(region);
 
-    EXPECT_EQ(definition.styleURL, region.getDefinition().styleURL);
-    EXPECT_EQ(definition.bounds, region.getDefinition().bounds);
-    EXPECT_EQ(definition.minZoom, region.getDefinition().minZoom);
-    EXPECT_EQ(definition.maxZoom, region.getDefinition().maxZoom);
-    EXPECT_EQ(definition.pixelRatio, region.getDefinition().pixelRatio);
-    EXPECT_EQ(metadata, region.getMetadata());
+    EXPECT_EQ(definition.styleURL, region->getDefinition().styleURL);
+    EXPECT_EQ(definition.bounds, region->getDefinition().bounds);
+    EXPECT_EQ(definition.minZoom, region->getDefinition().minZoom);
+    EXPECT_EQ(definition.maxZoom, region->getDefinition().maxZoom);
+    EXPECT_EQ(definition.pixelRatio, region->getDefinition().pixelRatio);
+    EXPECT_EQ(metadata, region->getMetadata());
 
     EXPECT_EQ(0u, log.uncheckedCount());
 }
@@ -245,10 +431,11 @@ TEST(OfflineDatabase, UpdateMetadata) {
     OfflineDatabase db(":memory:");
     OfflineRegionDefinition definition { "http://example.com/style", LatLngBounds::hull({1, 2}, {3, 4}), 5, 6, 2.0 };
     OfflineRegionMetadata metadata {{ 1, 2, 3 }};
-    OfflineRegion region = db.createRegion(definition, metadata);
+    auto region = db.createRegion(definition, metadata);
+    ASSERT_TRUE(region);
 
     OfflineRegionMetadata newmetadata {{ 4, 5, 6 }};
-    db.updateMetadata(region.getID(), newmetadata);
+    db.updateMetadata(region->getID(), newmetadata);
     EXPECT_EQ(db.listRegions().at(0).getMetadata(), newmetadata);
 
     EXPECT_EQ(0u, log.uncheckedCount());
@@ -260,11 +447,12 @@ TEST(OfflineDatabase, ListRegions) {
     OfflineRegionDefinition definition { "http://example.com/style", LatLngBounds::hull({1, 2}, {3, 4}), 5, 6, 2.0 };
     OfflineRegionMetadata metadata {{ 1, 2, 3 }};
 
-    OfflineRegion region = db.createRegion(definition, metadata);
+    auto region = db.createRegion(definition, metadata);
+    ASSERT_TRUE(region);
     std::vector<OfflineRegion> regions = db.listRegions();
 
     ASSERT_EQ(1u, regions.size());
-    EXPECT_EQ(region.getID(), regions.at(0).getID());
+    EXPECT_EQ(region->getID(), regions.at(0).getID());
     EXPECT_EQ(definition.styleURL, regions.at(0).getDefinition().styleURL);
     EXPECT_EQ(definition.bounds, regions.at(0).getDefinition().bounds);
     EXPECT_EQ(definition.minZoom, regions.at(0).getDefinition().minZoom);
@@ -281,14 +469,16 @@ TEST(OfflineDatabase, GetRegionDefinition) {
     OfflineRegionDefinition definition { "http://example.com/style", LatLngBounds::hull({1, 2}, {3, 4}), 5, 6, 2.0 };
     OfflineRegionMetadata metadata {{ 1, 2, 3 }};
 
-    OfflineRegion region = db.createRegion(definition, metadata);
-    OfflineRegionDefinition result = db.getRegionDefinition(region.getID());
+    auto region = db.createRegion(definition, metadata);
+    ASSERT_TRUE(region);
+    auto result = db.getRegionDefinition(region->getID());
+    ASSERT_TRUE(result);
 
-    EXPECT_EQ(definition.styleURL, result.styleURL);
-    EXPECT_EQ(definition.bounds, result.bounds);
-    EXPECT_EQ(definition.minZoom, result.minZoom);
-    EXPECT_EQ(definition.maxZoom, result.maxZoom);
-    EXPECT_EQ(definition.pixelRatio, result.pixelRatio);
+    EXPECT_EQ(definition.styleURL, result->styleURL);
+    EXPECT_EQ(definition.bounds, result->bounds);
+    EXPECT_EQ(definition.minZoom, result->minZoom);
+    EXPECT_EQ(definition.maxZoom, result->maxZoom);
+    EXPECT_EQ(definition.pixelRatio, result->pixelRatio);
 
     EXPECT_EQ(0u, log.uncheckedCount());
 }
@@ -298,15 +488,16 @@ TEST(OfflineDatabase, DeleteRegion) {
     OfflineDatabase db(":memory:");
     OfflineRegionDefinition definition { "http://example.com/style", LatLngBounds::hull({1, 2}, {3, 4}), 5, 6, 2.0 };
     OfflineRegionMetadata metadata {{ 1, 2, 3 }};
-    OfflineRegion region = db.createRegion(definition, metadata);
+    auto region = db.createRegion(definition, metadata);
+    ASSERT_TRUE(region);
 
     Response response;
     response.noContent = true;
 
-    db.putRegionResource(region.getID(), Resource::style("http://example.com/"), response);
-    db.putRegionResource(region.getID(), Resource::tile("http://example.com/", 1.0, 0, 0, 0, Tileset::Scheme::XYZ), response);
+    db.putRegionResource(region->getID(), Resource::style("http://example.com/"), response);
+    db.putRegionResource(region->getID(), Resource::tile("http://example.com/", 1.0, 0, 0, 0, Tileset::Scheme::XYZ), response);
 
-    db.deleteRegion(std::move(region));
+    db.deleteRegion(std::move(*region));
 
     ASSERT_EQ(0u, db.listRegions().size());
 
@@ -318,38 +509,35 @@ TEST(OfflineDatabase, CreateRegionInfiniteMaxZoom) {
     OfflineDatabase db(":memory:");
     OfflineRegionDefinition definition { "", LatLngBounds::world(), 0, INFINITY, 1.0 };
     OfflineRegionMetadata metadata;
-    OfflineRegion region = db.createRegion(definition, metadata);
+    auto region = db.createRegion(definition, metadata);
+    ASSERT_TRUE(region);
 
-    EXPECT_EQ(0, region.getDefinition().minZoom);
-    EXPECT_EQ(INFINITY, region.getDefinition().maxZoom);
+    EXPECT_EQ(0, region->getDefinition().minZoom);
+    EXPECT_EQ(INFINITY, region->getDefinition().maxZoom);
 
     EXPECT_EQ(0u, log.uncheckedCount());
 }
 
 TEST(OfflineDatabase, TEST_REQUIRES_WRITE(ConcurrentUse)) {
     FixtureLog log;
-    util::deleteFile(filename);
+    deleteDatabaseFiles();
 
     OfflineDatabase db1(filename);
     EXPECT_EQ(0u, log.uncheckedCount());
 
     OfflineDatabase db2(filename);
 
-    Resource resource { Resource::Style, "http://example.com/" };
-    Response response;
-    response.noContent = true;
-
     std::thread thread1([&] {
         for (auto i = 0; i < 100; i++) {
-            db1.put(resource, response);
-            EXPECT_TRUE(bool(db1.get(resource)));
+            db1.put(fixture::resource, fixture::response);
+            EXPECT_TRUE(bool(db1.get(fixture::resource)));
         }
     });
 
     std::thread thread2([&] {
         for (auto i = 0; i < 100; i++) {
-            db2.put(resource, response);
-            EXPECT_TRUE(bool(db2.get(resource)));
+            db2.put(fixture::resource, fixture::response);
+            EXPECT_TRUE(bool(db2.get(fixture::resource)));
         }
     });
 
@@ -411,13 +599,14 @@ TEST(OfflineDatabase, PutRegionResourceDoesNotEvict) {
     FixtureLog log;
     OfflineDatabase db(":memory:", 1024 * 100);
     OfflineRegionDefinition definition { "", LatLngBounds::world(), 0, INFINITY, 1.0 };
-    OfflineRegion region = db.createRegion(definition, OfflineRegionMetadata());
+    auto region = db.createRegion(definition, OfflineRegionMetadata());
+    ASSERT_TRUE(region);
 
     Response response;
     response.data = randomString(1024);
 
     for (uint32_t i = 1; i <= 100; i++) {
-        db.putRegionResource(region.getID(), Resource::style("http://example.com/"s + util::toString(i)), response);
+        db.putRegionResource(region->getID(), Resource::style("http://example.com/"s + util::toString(i)), response);
     }
 
     EXPECT_TRUE(bool(db.get(Resource::style("http://example.com/1"))));
@@ -448,32 +637,36 @@ TEST(OfflineDatabase, GetRegionCompletedStatus) {
     OfflineDatabase db(":memory:");
     OfflineRegionDefinition definition { "http://example.com/style", LatLngBounds::hull({1, 2}, {3, 4}), 5, 6, 2.0 };
     OfflineRegionMetadata metadata;
-    OfflineRegion region = db.createRegion(definition, metadata);
+    auto region = db.createRegion(definition, metadata);
+    ASSERT_TRUE(region);
 
-    OfflineRegionStatus status1 = db.getRegionCompletedStatus(region.getID());
-    EXPECT_EQ(0u, status1.completedResourceCount);
-    EXPECT_EQ(0u, status1.completedResourceSize);
-    EXPECT_EQ(0u, status1.completedTileCount);
-    EXPECT_EQ(0u, status1.completedTileSize);
+    auto status1 = db.getRegionCompletedStatus(region->getID());
+    ASSERT_TRUE(status1);
+    EXPECT_EQ(0u, status1->completedResourceCount);
+    EXPECT_EQ(0u, status1->completedResourceSize);
+    EXPECT_EQ(0u, status1->completedTileCount);
+    EXPECT_EQ(0u, status1->completedTileSize);
 
     Response response;
     response.data = std::make_shared<std::string>("data");
 
-    uint64_t styleSize = db.putRegionResource(region.getID(), Resource::style("http://example.com/"), response);
+    uint64_t styleSize = db.putRegionResource(region->getID(), Resource::style("http://example.com/"), response);
 
-    OfflineRegionStatus status2 = db.getRegionCompletedStatus(region.getID());
-    EXPECT_EQ(1u, status2.completedResourceCount);
-    EXPECT_EQ(styleSize, status2.completedResourceSize);
-    EXPECT_EQ(0u, status2.completedTileCount);
-    EXPECT_EQ(0u, status2.completedTileSize);
+    auto status2 = db.getRegionCompletedStatus(region->getID());
+    ASSERT_TRUE(status2);
+    EXPECT_EQ(1u, status2->completedResourceCount);
+    EXPECT_EQ(styleSize, status2->completedResourceSize);
+    EXPECT_EQ(0u, status2->completedTileCount);
+    EXPECT_EQ(0u, status2->completedTileSize);
 
-    uint64_t tileSize = db.putRegionResource(region.getID(), Resource::tile("http://example.com/", 1.0, 0, 0, 0, Tileset::Scheme::XYZ), response);
+    uint64_t tileSize = db.putRegionResource(region->getID(), Resource::tile("http://example.com/", 1.0, 0, 0, 0, Tileset::Scheme::XYZ), response);
 
-    OfflineRegionStatus status3 = db.getRegionCompletedStatus(region.getID());
-    EXPECT_EQ(2u, status3.completedResourceCount);
-    EXPECT_EQ(styleSize + tileSize, status3.completedResourceSize);
-    EXPECT_EQ(1u, status3.completedTileCount);
-    EXPECT_EQ(tileSize, status3.completedTileSize);
+    auto status3 = db.getRegionCompletedStatus(region->getID());
+    ASSERT_TRUE(status3);
+    EXPECT_EQ(2u, status3->completedResourceCount);
+    EXPECT_EQ(styleSize + tileSize, status3->completedResourceSize);
+    EXPECT_EQ(1u, status3->completedTileCount);
+    EXPECT_EQ(tileSize, status3->completedTileSize);
 
     EXPECT_EQ(0u, log.uncheckedCount());
 }
@@ -482,21 +675,22 @@ TEST(OfflineDatabase, HasRegionResource) {
     FixtureLog log;
     OfflineDatabase db(":memory:", 1024 * 100);
     OfflineRegionDefinition definition { "", LatLngBounds::world(), 0, INFINITY, 1.0 };
-    OfflineRegion region = db.createRegion(definition, OfflineRegionMetadata());
+    auto region = db.createRegion(definition, OfflineRegionMetadata());
+    ASSERT_TRUE(region);
 
-    EXPECT_FALSE(bool(db.hasRegionResource(region.getID(), Resource::style("http://example.com/1"))));
-    EXPECT_FALSE(bool(db.hasRegionResource(region.getID(), Resource::style("http://example.com/20"))));
+    EXPECT_FALSE(bool(db.hasRegionResource(region->getID(), Resource::style("http://example.com/1"))));
+    EXPECT_FALSE(bool(db.hasRegionResource(region->getID(), Resource::style("http://example.com/20"))));
 
     Response response;
     response.data = randomString(1024);
 
     for (uint32_t i = 1; i <= 100; i++) {
-        db.putRegionResource(region.getID(), Resource::style("http://example.com/"s + util::toString(i)), response);
+        db.putRegionResource(region->getID(), Resource::style("http://example.com/"s + util::toString(i)), response);
     }
 
-    EXPECT_TRUE(bool(db.hasRegionResource(region.getID(), Resource::style("http://example.com/1"))));
-    EXPECT_TRUE(bool(db.hasRegionResource(region.getID(), Resource::style("http://example.com/20"))));
-    EXPECT_EQ(1024, *(db.hasRegionResource(region.getID(), Resource::style("http://example.com/20"))));
+    EXPECT_TRUE(bool(db.hasRegionResource(region->getID(), Resource::style("http://example.com/1"))));
+    EXPECT_TRUE(bool(db.hasRegionResource(region->getID(), Resource::style("http://example.com/20"))));
+    EXPECT_EQ(1024, *(db.hasRegionResource(region->getID(), Resource::style("http://example.com/20"))));
 
     EXPECT_EQ(0u, log.uncheckedCount());
 }
@@ -505,7 +699,8 @@ TEST(OfflineDatabase, HasRegionResourceTile) {
     FixtureLog log;
     OfflineDatabase db(":memory:", 1024 * 100);
     OfflineRegionDefinition definition { "", LatLngBounds::world(), 0, INFINITY, 1.0 };
-    OfflineRegion region = db.createRegion(definition, OfflineRegionMetadata());
+    auto region = db.createRegion(definition, OfflineRegionMetadata());
+    ASSERT_TRUE(region);
 
     Resource resource { Resource::Tile, "http://example.com/" };
     resource.tileData = Resource::TileData {
@@ -519,15 +714,16 @@ TEST(OfflineDatabase, HasRegionResourceTile) {
 
     response.data = std::make_shared<std::string>("first");
 
-    EXPECT_FALSE(bool(db.hasRegionResource(region.getID(), resource)));
-    db.putRegionResource(region.getID(), resource, response);
-    EXPECT_TRUE(bool(db.hasRegionResource(region.getID(), resource)));
-    EXPECT_EQ(5, *(db.hasRegionResource(region.getID(), resource)));
+    EXPECT_FALSE(bool(db.hasRegionResource(region->getID(), resource)));
+    db.putRegionResource(region->getID(), resource, response);
+    EXPECT_TRUE(bool(db.hasRegionResource(region->getID(), resource)));
+    EXPECT_EQ(5, *(db.hasRegionResource(region->getID(), resource)));
 
-    OfflineRegion anotherRegion = db.createRegion(definition, OfflineRegionMetadata());
-    EXPECT_LT(region.getID(), anotherRegion.getID());
-    EXPECT_TRUE(bool(db.hasRegionResource(anotherRegion.getID(), resource)));
-    EXPECT_EQ(5, *(db.hasRegionResource(anotherRegion.getID(), resource)));
+    auto anotherRegion = db.createRegion(definition, OfflineRegionMetadata());
+    ASSERT_TRUE(anotherRegion);
+    EXPECT_LT(region->getID(), anotherRegion->getID());
+    EXPECT_TRUE(bool(db.hasRegionResource(anotherRegion->getID(), resource)));
+    EXPECT_EQ(5, *(db.hasRegionResource(anotherRegion->getID(), resource)));
 
     EXPECT_EQ(0u, log.uncheckedCount());
 
@@ -539,8 +735,10 @@ TEST(OfflineDatabase, OfflineMapboxTileCount) {
     OfflineRegionDefinition definition { "http://example.com/style", LatLngBounds::hull({1, 2}, {3, 4}), 5, 6, 2.0 };
     OfflineRegionMetadata metadata;
 
-    OfflineRegion region1 = db.createRegion(definition, metadata);
-    OfflineRegion region2 = db.createRegion(definition, metadata);
+    auto region1 = db.createRegion(definition, metadata);
+    ASSERT_TRUE(region1);
+    auto region2 = db.createRegion(definition, metadata);
+    ASSERT_TRUE(region2);
 
     Resource nonMapboxTile = Resource::tile("http://example.com/", 1.0, 0, 0, 0, Tileset::Scheme::XYZ);
     Resource mapboxTile1 = Resource::tile("mapbox://tiles/1", 1.0, 0, 0, 0, Tileset::Scheme::XYZ);
@@ -553,27 +751,27 @@ TEST(OfflineDatabase, OfflineMapboxTileCount) {
     EXPECT_EQ(0u, db.getOfflineMapboxTileCount());
 
     // Count stays the same after putting a non-tile resource.
-    db.putRegionResource(region1.getID(), Resource::style("http://example.com/"), response);
+    db.putRegionResource(region1->getID(), Resource::style("http://example.com/"), response);
     EXPECT_EQ(0u, db.getOfflineMapboxTileCount());
 
     // Count stays the same after putting a non-Mapbox tile.
-    db.putRegionResource(region1.getID(), nonMapboxTile, response);
+    db.putRegionResource(region1->getID(), nonMapboxTile, response);
     EXPECT_EQ(0u, db.getOfflineMapboxTileCount());
 
     // Count increases after putting a Mapbox tile not used by another region.
-    db.putRegionResource(region1.getID(), mapboxTile1, response);
+    db.putRegionResource(region1->getID(), mapboxTile1, response);
     EXPECT_EQ(1u, db.getOfflineMapboxTileCount());
 
     // Count stays the same after putting a Mapbox tile used by another region.
-    db.putRegionResource(region2.getID(), mapboxTile1, response);
+    db.putRegionResource(region2->getID(), mapboxTile1, response);
     EXPECT_EQ(1u, db.getOfflineMapboxTileCount());
 
     // Count stays the same after putting a Mapbox tile used by the same region.
-    db.putRegionResource(region2.getID(), mapboxTile1, response);
+    db.putRegionResource(region2->getID(), mapboxTile1, response);
     EXPECT_EQ(1u, db.getOfflineMapboxTileCount());
 
     // Count stays the same after deleting a region when the tile is still used by another region.
-    db.deleteRegion(std::move(region2));
+    db.deleteRegion(std::move(*region2));
     EXPECT_EQ(1u, db.getOfflineMapboxTileCount());
 
     // Count stays the same after the putting a non-offline Mapbox tile.
@@ -581,11 +779,11 @@ TEST(OfflineDatabase, OfflineMapboxTileCount) {
     EXPECT_EQ(1u, db.getOfflineMapboxTileCount());
 
     // Count increases after putting a pre-existing, but non-offline Mapbox tile.
-    db.putRegionResource(region1.getID(), mapboxTile2, response);
+    db.putRegionResource(region1->getID(), mapboxTile2, response);
     EXPECT_EQ(2u, db.getOfflineMapboxTileCount());
 
     // Count decreases after deleting a region when the tiles are not used by other regions.
-    db.deleteRegion(std::move(region1));
+    db.deleteRegion(std::move(*region1));
     EXPECT_EQ(0u, db.getOfflineMapboxTileCount());
 
     EXPECT_EQ(0u, log.uncheckedCount());
@@ -596,7 +794,8 @@ TEST(OfflineDatabase, BatchInsertion) {
     FixtureLog log;
     OfflineDatabase db(":memory:", 1024 * 100);
     OfflineRegionDefinition definition { "", LatLngBounds::world(), 0, INFINITY, 1.0 };
-    OfflineRegion region = db.createRegion(definition, OfflineRegionMetadata());
+    auto region = db.createRegion(definition, OfflineRegionMetadata());
+    ASSERT_TRUE(region);
 
     Response response;
     response.data = randomString(1024);
@@ -607,7 +806,7 @@ TEST(OfflineDatabase, BatchInsertion) {
     }
 
     OfflineRegionStatus status;
-    db.putRegionResources(region.getID(), resources, status);
+    db.putRegionResources(region->getID(), resources, status);
 
     for (uint32_t i = 1; i <= 100; i++) {
         EXPECT_TRUE(bool(db.get(Resource::style("http://example.com/"s + util::toString(i)))));
@@ -621,7 +820,8 @@ TEST(OfflineDatabase, BatchInsertionMapboxTileCountExceeded) {
     OfflineDatabase db(":memory:", 1024 * 100);
     db.setOfflineMapboxTileCountLimit(1);
     OfflineRegionDefinition definition { "", LatLngBounds::world(), 0, INFINITY, 1.0 };
-    OfflineRegion region = db.createRegion(definition, OfflineRegionMetadata());
+    auto region = db.createRegion(definition, OfflineRegionMetadata());
+    ASSERT_TRUE(region);
 
     Response response;
     response.data = randomString(1024);
@@ -633,68 +833,26 @@ TEST(OfflineDatabase, BatchInsertionMapboxTileCountExceeded) {
 
     OfflineRegionStatus status;
     try {
-        db.putRegionResources(region.getID(), resources, status);
+        db.putRegionResources(region->getID(), resources, status);
         EXPECT_FALSE(true);
     } catch (const MapboxTileLimitExceededException&) {
         // Expected
     }
 
-    EXPECT_EQ(status.completedTileCount, 1u);
-    EXPECT_EQ(status.completedResourceCount, 2u);
-    EXPECT_EQ(db.getRegionCompletedStatus(region.getID()).completedTileCount, 1u);
-    EXPECT_EQ(db.getRegionCompletedStatus(region.getID()).completedResourceCount, 2u);
+    EXPECT_EQ(0u, status.completedTileCount);
+    EXPECT_EQ(0u, status.completedResourceCount);
+    const auto completedStatus = db.getRegionCompletedStatus(region->getID());
+    ASSERT_TRUE(completedStatus);
+    EXPECT_EQ(1u, completedStatus->completedTileCount);
+    EXPECT_EQ(2u, completedStatus->completedResourceCount);
 
     EXPECT_EQ(0u, log.uncheckedCount());
 }
 
-static int databasePageCount(const std::string& path) {
-    mapbox::sqlite::Database db = mapbox::sqlite::Database::open(path, mapbox::sqlite::ReadOnly);
-    mapbox::sqlite::Statement stmt{ db, "pragma page_count" };
-    mapbox::sqlite::Query query{ stmt };
-    query.run();
-    return query.get<int>(0);
-}
-
-static int databaseUserVersion(const std::string& path) {
-    mapbox::sqlite::Database db = mapbox::sqlite::Database::open(path, mapbox::sqlite::ReadOnly);
-    mapbox::sqlite::Statement stmt{ db, "pragma user_version" };
-    mapbox::sqlite::Query query{ stmt };
-    query.run();
-    return query.get<int>(0);
-}
-
-static std::string databaseJournalMode(const std::string& path) {
-    mapbox::sqlite::Database db = mapbox::sqlite::Database::open(path, mapbox::sqlite::ReadOnly);
-    mapbox::sqlite::Statement stmt{ db, "pragma journal_mode" };
-    mapbox::sqlite::Query query{ stmt };
-    query.run();
-    return query.get<std::string>(0);
-}
-
-static int databaseSyncMode(const std::string& path) {
-    mapbox::sqlite::Database db = mapbox::sqlite::Database::open(path, mapbox::sqlite::ReadOnly);
-    mapbox::sqlite::Statement stmt{ db, "pragma synchronous" };
-    mapbox::sqlite::Query query{ stmt };
-    query.run();
-    return query.get<int>(0);
-}
-
-static std::vector<std::string> databaseTableColumns(const std::string& path, const std::string& name) {
-    mapbox::sqlite::Database db = mapbox::sqlite::Database::open(path, mapbox::sqlite::ReadOnly);
-    const auto sql = std::string("pragma table_info(") + name + ")";
-    mapbox::sqlite::Statement stmt{ db, sql.c_str() };
-    mapbox::sqlite::Query query{ stmt };
-    std::vector<std::string> columns;
-    while (query.run()) {
-        columns.push_back(query.get<std::string>(1));
-    }
-    return columns;
-}
-
 TEST(OfflineDatabase, MigrateFromV2Schema) {
     // v2.db is a v2 database containing a single offline region with a small number of resources.
     FixtureLog log;
-    util::deleteFile(filename);
+    deleteDatabaseFiles();
     util::copyFile(filename, "test/fixtures/offline_database/v2.db");
 
     {
@@ -715,7 +873,7 @@ TEST(OfflineDatabase, MigrateFromV2Schema) {
 TEST(OfflineDatabase, MigrateFromV3Schema) {
     // v3.db is a v3 database, migrated from v2.
     FixtureLog log;
-    util::deleteFile(filename);
+    deleteDatabaseFiles();
     util::copyFile(filename, "test/fixtures/offline_database/v3.db");
 
     {
@@ -734,7 +892,7 @@ TEST(OfflineDatabase, MigrateFromV3Schema) {
 TEST(OfflineDatabase, MigrateFromV4Schema) {
     // v4.db is a v4 database, migrated from v2 & v3. This database used `journal_mode = WAL` and `synchronous = NORMAL`.
     FixtureLog log;
-    util::deleteFile(filename);
+    deleteDatabaseFiles();
     util::copyFile(filename, "test/fixtures/offline_database/v4.db");
 
     {
@@ -760,7 +918,7 @@ TEST(OfflineDatabase, MigrateFromV4Schema) {
 TEST(OfflineDatabase, MigrateFromV5Schema) {
     // v5.db is a v5 database, migrated from v2, v3 & v4.
     FixtureLog log;
-    util::deleteFile(filename);
+    deleteDatabaseFiles();
     util::copyFile(filename, "test/fixtures/offline_database/v5.db");
 
     {
@@ -808,3 +966,133 @@ TEST(OfflineDatabase, DowngradeSchema) {
     EXPECT_EQ(1u, log.count({ EventSeverity::Warning, Event::Database, -1, "Removing existing incompatible offline database" }));
     EXPECT_EQ(0u, log.uncheckedCount());
 }
+
+TEST(OfflineDatabase, CorruptDatabaseOnOpen) {
+    FixtureLog log;
+    util::deleteFile(filename);
+    util::copyFile(filename, "test/fixtures/offline_database/corrupt-immediate.db");
+
+    // This database is corrupt in a way that will prevent opening the database.
+    OfflineDatabase db(filename);
+    EXPECT_EQ(1u, log.count(error(ResultCode::Corrupt, "Can't open database: database disk image is malformed"), true));
+    EXPECT_EQ(1u, log.count(warning(static_cast<ResultCode>(-1), "Removing existing incompatible offline database")));
+    EXPECT_EQ(0u, log.uncheckedCount());
+
+    // Now try inserting and reading back to make sure we have a valid database.
+    for (const auto& res : { fixture::resource, fixture::tile }) {
+        EXPECT_EQ(std::make_pair(true, uint64_t(5)), db.put(res, fixture::response));
+        EXPECT_EQ(0u, log.uncheckedCount());
+        auto result = db.get(res);
+        EXPECT_EQ(0u, log.uncheckedCount());
+        ASSERT_TRUE(result && result->data);
+        EXPECT_EQ("first", *result->data);
+    }
+}
+
+TEST(OfflineDatabase, CorruptDatabaseOnQuery) {
+    FixtureLog log;
+    util::deleteFile(filename);
+    util::copyFile(filename, "test/fixtures/offline_database/corrupt-delayed.db");
+
+    // This database is corrupt in a way that won't manifest itself until we start querying it,
+    // so just opening it will not cause an error.
+    OfflineDatabase db(filename);
+
+    // Just opening this corrupt database should not have produced an error yet, since
+    // PRAGMA user_version still succeeds with this database.
+    EXPECT_EQ(0u, log.uncheckedCount());
+
+    // The first request fails because the database is corrupt and has to be recreated.
+    EXPECT_EQ(nullopt, db.get(fixture::tile));
+    EXPECT_EQ(1u, log.count(error(ResultCode::Corrupt, "Can't read resource: database disk image is malformed"), true));
+    EXPECT_EQ(1u, log.count(warning(static_cast<ResultCode>(-1), "Removing existing incompatible offline database")));
+    EXPECT_EQ(0u, log.uncheckedCount());
+
+    // Now try inserting and reading back to make sure we have a valid database.
+    for (const auto& res : { fixture::resource, fixture::tile }) {
+        EXPECT_EQ(std::make_pair(true, uint64_t(5)), db.put(res, fixture::response));
+        EXPECT_EQ(0u, log.uncheckedCount());
+        auto result = db.get(res);
+        EXPECT_EQ(0u, log.uncheckedCount());
+        ASSERT_TRUE(result && result->data);
+        EXPECT_EQ("first", *result->data);
+    }
+}
+
+#ifndef __QT__ // Qt doesn't expose the ability to register virtual file system handlers.
+TEST(OfflineDatabase, TEST_REQUIRES_WRITE(DisallowedIO)) {
+    FixtureLog log;
+    deleteDatabaseFiles();
+    test::SQLite3TestFS fs;
+
+    OfflineDatabase db(filename_test_fs);
+    EXPECT_EQ(0u, log.uncheckedCount());
+
+    // First, create a region object so that we can try deleting it later.
+    OfflineTilePyramidRegionDefinition definition(
+        "mapbox://style", LatLngBounds::hull({ 37.66, -122.57 }, { 37.83, -122.32 }), 0, 8, 2);
+    auto region = db.createRegion(definition, {});
+    ASSERT_TRUE(region);
+
+    // Now forbid any type of IO on the database and test that none of the calls crashes.
+    fs.allowIO(false);
+
+    EXPECT_EQ(nullopt, db.get(fixture::resource));
+    EXPECT_EQ(1u, log.count(warning(ResultCode::Auth, "Can't update timestamp: authorization denied")));
+    EXPECT_EQ(1u, log.count(warning(ResultCode::Auth, "Can't read resource: authorization denied")));
+    EXPECT_EQ(0u, log.uncheckedCount());
+
+    EXPECT_EQ(std::make_pair(false, uint64_t(0)), db.put(fixture::resource, fixture::response));
+    EXPECT_EQ(1u, log.count(warning(ResultCode::Auth, "Can't write resource: authorization denied")));
+    EXPECT_EQ(0u, log.uncheckedCount());
+
+    const auto regions = db.listRegions();
+    EXPECT_TRUE(regions.empty());
+    EXPECT_EQ(1u, log.count(warning(ResultCode::Auth, "Can't list regions: authorization denied")));
+    EXPECT_EQ(0u, log.uncheckedCount());
+
+    EXPECT_EQ(nullopt, db.createRegion(definition, {}));
+    EXPECT_EQ(1u, log.count(warning(ResultCode::Auth, "Can't create region: authorization denied")));
+    EXPECT_EQ(0u, log.uncheckedCount());
+
+    EXPECT_EQ(nullopt, db.updateMetadata(region->getID(), {}));
+    EXPECT_EQ(1u, log.count(warning(ResultCode::Auth, "Can't update region metadata: authorization denied")));
+    EXPECT_EQ(0u, log.uncheckedCount());
+
+    EXPECT_EQ(nullopt, db.getRegionResource(region->getID(), fixture::resource));
+    EXPECT_EQ(1u, log.count(warning(ResultCode::Auth, "Can't update timestamp: authorization denied")));
+    EXPECT_EQ(1u, log.count(warning(ResultCode::Auth, "Can't read region resource: authorization denied")));
+    EXPECT_EQ(0u, log.uncheckedCount());
+
+    EXPECT_EQ(nullopt, db.hasRegionResource(region->getID(), fixture::resource));
+    EXPECT_EQ(1u, log.count(warning(ResultCode::Auth, "Can't query region resource: authorization denied")));
+    EXPECT_EQ(0u, log.uncheckedCount());
+
+    EXPECT_EQ(0u, db.putRegionResource(region->getID(), fixture::resource, fixture::response));
+    EXPECT_EQ(1u, log.count(warning(ResultCode::Auth, "Can't write region resource: authorization denied")));
+    EXPECT_EQ(0u, log.uncheckedCount());
+
+    OfflineRegionStatus status;
+    db.putRegionResources(region->getID(), { std::make_tuple(fixture::resource, fixture::response) }, status);
+    EXPECT_EQ(1u, log.count(warning(ResultCode::Auth, "Can't write region resources: authorization denied")));
+    EXPECT_EQ(0u, log.uncheckedCount());
+
+    EXPECT_EQ(nullopt, db.getRegionDefinition(region->getID()));
+    EXPECT_EQ(1u, log.count(warning(ResultCode::Auth, "Can't load region: authorization denied")));
+    EXPECT_EQ(0u, log.uncheckedCount());
+
+    EXPECT_EQ(nullopt, db.getRegionCompletedStatus(region->getID()));
+    EXPECT_EQ(1u, log.count(warning(ResultCode::Auth, "Can't get region status: authorization denied")));
+    EXPECT_EQ(0u, log.uncheckedCount());
+
+    db.deleteRegion(std::move(*region));
+    EXPECT_EQ(1u, log.count(warning(ResultCode::Auth, "Can't delete region: authorization denied")));
+    EXPECT_EQ(0u, log.uncheckedCount());
+
+    EXPECT_EQ(std::numeric_limits<uint64_t>::max(), db.getOfflineMapboxTileCount());
+    EXPECT_EQ(1u, log.count(warning(ResultCode::Auth, "Can't get offline Mapbox tile count: authorization denied")));
+    EXPECT_EQ(0u, log.uncheckedCount());
+
+    fs.reset();
+}
+#endif // __QT__
diff --git a/test/storage/offline_download.test.cpp b/test/storage/offline_download.test.cpp
index 57780eba40..e87ad6c370 100644
--- a/test/storage/offline_download.test.cpp
+++ b/test/storage/offline_download.test.cpp
@@ -42,7 +42,7 @@ public:
     OfflineDatabase db { ":memory:" };
     std::size_t size = 0;
 
-    OfflineRegion createRegion() {
+    optional<OfflineRegion> createRegion() {
         OfflineRegionDefinition definition { "", LatLngBounds::hull({1, 2}, {3, 4}), 5, 6, 1.0 };
         OfflineRegionMetadata metadata;
         return db.createRegion(definition, metadata);
@@ -60,9 +60,10 @@ public:
 
 TEST(OfflineDownload, NoSubresources) {
     OfflineTest test;
-    OfflineRegion region = test.createRegion();
+    auto region = test.createRegion();
+    ASSERT_TRUE(region);
     OfflineDownload download(
-        region.getID(),
+        region->getID(),
         OfflineTilePyramidRegionDefinition("http://127.0.0.1:3000/style.json", LatLngBounds::world(), 0.0, 0.0, 1.0),
         test.db, test.fileSource);
 
@@ -100,9 +101,10 @@ TEST(OfflineDownload, NoSubresources) {
 
 TEST(OfflineDownload, InlineSource) {
     OfflineTest test;
-    OfflineRegion region = test.createRegion();
+    auto region = test.createRegion();
+    ASSERT_TRUE(region);
     OfflineDownload download(
-        region.getID(),
+        region->getID(),
         OfflineTilePyramidRegionDefinition("http://127.0.0.1:3000/style.json", LatLngBounds::world(), 0.0, 0.0, 1.0),
         test.db, test.fileSource);
 
@@ -140,9 +142,10 @@ TEST(OfflineDownload, InlineSource) {
 
 TEST(OfflineDownload, GeoJSONSource) {
     OfflineTest test;
-    OfflineRegion region = test.createRegion();
+    auto region = test.createRegion();
+    ASSERT_TRUE(region);
     OfflineDownload download(
-        region.getID(),
+        region->getID(),
         OfflineTilePyramidRegionDefinition("http://127.0.0.1:3000/style.json", LatLngBounds::world(), 0.0, 0.0, 1.0),
         test.db, test.fileSource);
 
@@ -175,9 +178,10 @@ TEST(OfflineDownload, GeoJSONSource) {
 
 TEST(OfflineDownload, Activate) {
     OfflineTest test;
-    OfflineRegion region = test.createRegion();
+    auto region = test.createRegion();
+    ASSERT_TRUE(region);
     OfflineDownload download(
-        region.getID(),
+        region->getID(),
         OfflineTilePyramidRegionDefinition("http://127.0.0.1:3000/style.json", LatLngBounds::world(), 0.0, 0.0, 1.0),
         test.db, test.fileSource);
 
@@ -250,9 +254,10 @@ TEST(OfflineDownload, Activate) {
 TEST(OfflineDownload, DoesNotFloodTheFileSourceWithRequests) {
     FakeFileSource fileSource;
     OfflineTest test;
-    OfflineRegion region = test.createRegion();
+    auto region = test.createRegion();
+    ASSERT_TRUE(region);
     OfflineDownload download(
-        region.getID(),
+        region->getID(),
         OfflineTilePyramidRegionDefinition("http://127.0.0.1:3000/style.json", LatLngBounds::world(), 0.0, 0.0, 1.0),
         test.db, fileSource);
 
@@ -272,9 +277,10 @@ TEST(OfflineDownload, DoesNotFloodTheFileSourceWithRequests) {
 
 TEST(OfflineDownload, GetStatusNoResources) {
     OfflineTest test;
-    OfflineRegion region = test.createRegion();
+    auto region = test.createRegion();
+    ASSERT_TRUE(region);
     OfflineDownload download(
-        region.getID(),
+        region->getID(),
         OfflineTilePyramidRegionDefinition("http://127.0.0.1:3000/style.json", LatLngBounds::world(), 0.0, 0.0, 1.0),
         test.db, test.fileSource);
     OfflineRegionStatus status = download.getStatus();
@@ -289,9 +295,10 @@ TEST(OfflineDownload, GetStatusNoResources) {
 
 TEST(OfflineDownload, GetStatusStyleComplete) {
     OfflineTest test;
-    OfflineRegion region = test.createRegion();
+    auto region = test.createRegion();
+    ASSERT_TRUE(region);
     OfflineDownload download(
-        region.getID(),
+        region->getID(),
         OfflineTilePyramidRegionDefinition("http://127.0.0.1:3000/style.json", LatLngBounds::world(), 0.0, 0.0, 1.0),
         test.db, test.fileSource);
 
@@ -311,9 +318,10 @@ TEST(OfflineDownload, GetStatusStyleComplete) {
 
 TEST(OfflineDownload, GetStatusStyleAndSourceComplete) {
     OfflineTest test;
-    OfflineRegion region = test.createRegion();
+    auto region = test.createRegion();
+    ASSERT_TRUE(region);
     OfflineDownload download(
-        region.getID(),
+        region->getID(),
         OfflineTilePyramidRegionDefinition("http://127.0.0.1:3000/style.json", LatLngBounds::world(), 0.0, 0.0, 1.0),
         test.db, test.fileSource);
 
@@ -337,9 +345,10 @@ TEST(OfflineDownload, GetStatusStyleAndSourceComplete) {
 
 TEST(OfflineDownload, RequestError) {
     OfflineTest test;
-    OfflineRegion region = test.createRegion();
+    auto region = test.createRegion();
+    ASSERT_TRUE(region);
     OfflineDownload download(
-        region.getID(),
+        region->getID(),
         OfflineTilePyramidRegionDefinition("http://127.0.0.1:3000/style.json", LatLngBounds::world(), 0.0, 0.0, 1.0),
         test.db, test.fileSource);
 
@@ -365,9 +374,10 @@ TEST(OfflineDownload, RequestError) {
 
 TEST(OfflineDownload, RequestErrorsAreRetried) {
     OfflineTest test;
-    OfflineRegion region = test.createRegion();
+    auto region = test.createRegion();
+    ASSERT_TRUE(region);
     OfflineDownload download(
-        region.getID(),
+        region->getID(),
         OfflineTilePyramidRegionDefinition("http://127.0.0.1:3000/style.json", LatLngBounds::world(), 0.0, 0.0, 1.0),
         test.db, test.fileSource);
 
@@ -398,9 +408,10 @@ TEST(OfflineDownload, RequestErrorsAreRetried) {
 
 TEST(OfflineDownload, TileCountLimitExceededNoTileResponse) {
     OfflineTest test;
-    OfflineRegion region = test.createRegion();
+    auto region = test.createRegion();
+    ASSERT_TRUE(region);
     OfflineDownload download(
-        region.getID(),
+        region->getID(),
         OfflineTilePyramidRegionDefinition("http://127.0.0.1:3000/style.json", LatLngBounds::world(), 0.0, 0.0, 1.0),
         test.db, test.fileSource);
 
@@ -440,9 +451,10 @@ TEST(OfflineDownload, TileCountLimitExceededNoTileResponse) {
 
 TEST(OfflineDownload, TileCountLimitExceededWithTileResponse) {
     OfflineTest test;
-    OfflineRegion region = test.createRegion();
+    auto region = test.createRegion();
+    ASSERT_TRUE(region);
     OfflineDownload download(
-        region.getID(),
+        region->getID(),
         OfflineTilePyramidRegionDefinition("http://127.0.0.1:3000/style.json", LatLngBounds::world(), 0.0, 0.0, 1.0),
         test.db, test.fileSource);
 
@@ -494,9 +506,10 @@ TEST(OfflineDownload, TileCountLimitExceededWithTileResponse) {
 
 TEST(OfflineDownload, WithPreviouslyExistingTile) {
     OfflineTest test;
-    OfflineRegion region = test.createRegion();
+    auto region = test.createRegion();
+    ASSERT_TRUE(region);
     OfflineDownload download(
-        region.getID(),
+        region->getID(),
         OfflineTilePyramidRegionDefinition("http://127.0.0.1:3000/style.json", LatLngBounds::world(), 0.0, 0.0, 1.0),
         test.db, test.fileSource);
 
@@ -528,9 +541,10 @@ TEST(OfflineDownload, WithPreviouslyExistingTile) {
 
 TEST(OfflineDownload, ReactivatePreviouslyCompletedDownload) {
     OfflineTest test;
-    OfflineRegion region = test.createRegion();
+    auto region = test.createRegion();
+    ASSERT_TRUE(region);
     OfflineDownload download(
-        region.getID(),
+        region->getID(),
         OfflineTilePyramidRegionDefinition("http://127.0.0.1:3000/style.json", LatLngBounds::world(), 0.0, 0.0, 1.0),
         test.db, test.fileSource);
 
@@ -556,7 +570,7 @@ TEST(OfflineDownload, ReactivatePreviouslyCompletedDownload) {
     test.loop.run();
 
     OfflineDownload redownload(
-        region.getID(),
+        region->getID(),
         OfflineTilePyramidRegionDefinition("http://127.0.0.1:3000/style.json", LatLngBounds::world(), 0.0, 0.0, 1.0),
         test.db, test.fileSource);
 
@@ -595,9 +609,10 @@ TEST(OfflineDownload, ReactivatePreviouslyCompletedDownload) {
 
 TEST(OfflineDownload, Deactivate) {
     OfflineTest test;
-    OfflineRegion region = test.createRegion();
+    auto region = test.createRegion();
+    ASSERT_TRUE(region);
     OfflineDownload download(
-        region.getID(),
+        region->getID(),
         OfflineTilePyramidRegionDefinition("http://127.0.0.1:3000/style.json", LatLngBounds::world(), 0.0, 0.0, 1.0),
         test.db, test.fileSource);
 
diff --git a/test/storage/sqlite.test.cpp b/test/storage/sqlite.test.cpp
index 22958c8bed..cdbb7f26d7 100644
--- a/test/storage/sqlite.test.cpp
+++ b/test/storage/sqlite.test.cpp
@@ -38,12 +38,6 @@ TEST(SQLite, TEST_REQUIRES_WRITE(TryOpen)) {
     auto result = mapbox::sqlite::Database::tryOpen("test/fixtures/offline_database/foobar123.db", mapbox::sqlite::ReadOnly);
     ASSERT_TRUE(result.is<mapbox::sqlite::Exception>());
     ASSERT_EQ(result.get<mapbox::sqlite::Exception>().code, mapbox::sqlite::ResultCode::CantOpen);
-
-#ifndef __QT__
-    // Only non-Qt platforms are setting a logger on the SQLite object.
-    EXPECT_EQ(1u, log.count({ EventSeverity::Info, Event::Database, static_cast<int64_t>(mapbox::sqlite::ResultCode::CantOpen), "cannot open file" }, true));
-    EXPECT_EQ(1u, log.count({ EventSeverity::Info, Event::Database, static_cast<int64_t>(mapbox::sqlite::ResultCode::CantOpen), "No such file or directory" }, true));
-#endif
     EXPECT_EQ(0u, log.uncheckedCount());
 }