Add SQLite database application ID and new consistent file extension (#329)

This PR adds the `3948349` integer as the [SQLite Application
ID](https://sqlite.org/fileformat.html#application_id) that is standard
procedure to take when a SQLite database is used as an application file
format[^1]. A new consistent file extension has been chosen.

1. `PRAGMA application_id = SQLITE_DB_APPLICATION_ID` is set for new and
old databases
2. New databases are created with the new file extension
3. Legacy files are renamed for backward compatibility

[^1]: https://sqlite.org/appfileformat.html

Author: zaerl

composer.json

@@ -65,7 +65,7 @@
 		],
 		"wp-test-php": [
 			"@wp-test-ensure-env @no_additional_args",
-			"rm -rf wordpress/src/wp-content/database/.ht.sqlite @no_additional_args",
+			"rm -rf wordpress/src/wp-content/database/.ht.sqlite.php @no_additional_args",
 			"npm --prefix wordpress run test:php -- @additional_args"
 		],
 		"wp-test-e2e": [
@@ -74,7 +74,7 @@
 		],
 		"wp-test-clean": [
 			"npm --prefix wordpress run env:clean",
-			"rm -rf wordpress/src/wp-content/database/.ht.sqlite"
+			"rm -rf wordpress/src/wp-content/database/.ht.sqlite.php"
 		]
 	}
 }

constants.php

@@ -48,7 +48,7 @@
 	if ( defined( 'DB_FILE' ) ) {
 		define( 'FQDB', FQDBDIR . DB_FILE );
 	} else {
-		define( 'FQDB', FQDBDIR . '.ht.sqlite' );
+		define( 'FQDB', FQDBDIR . '.ht.sqlite.php' );
 	}
 }
 

tests/WP_SQLite_Driver_Tests.php

@@ -15,7 +15,12 @@ public function setUp(): void {
 		$this->sqlite = new $pdo_class( 'sqlite::memory:' );
 
 		$this->engine = new WP_SQLite_Driver(
-			new WP_SQLite_Connection( array( 'pdo' => $this->sqlite ) ),
+			new WP_SQLite_Connection(
+				array(
+					'pdo'            => $this->sqlite,
+					'application_id' => 42, // Test application ID.
+				)
+			),
 			'wp'
 		);
 		$this->engine->query(
@@ -51,6 +56,11 @@ private function assertQueryError( $sql, $error_message ) {
 		$this->assertSame( $error_message, $exception->getMessage() );
 	}
 
+	public function testApplicationID() {
+		$app_id = $this->sqlite->query( 'PRAGMA application_id' )->fetchColumn();
+		$this->assertSame( 42, (int) $app_id );
+	}
+
 	public function testRegexp() {
 		$this->assertQuery(
 			"INSERT INTO _options (option_name, option_value) VALUES ('rss_0123456789abcdef0123456789abcdef', '1');"

tests/bootstrap.php

@@ -1,6 +1,12 @@
 <?php
 
+// Configure the test environment.
+error_reporting( E_ALL );
+define( 'FQDB', ':memory:' );
+define( 'FQDBDIR', __DIR__ . '/../testdb' );
+
 require_once __DIR__ . '/wp-sqlite-schema.php';
+require_once __DIR__ . '/../constants.php';
 require_once __DIR__ . '/../wp-pdo-mysql-on-sqlite.php';
 require_once __DIR__ . '/../wp-includes/sqlite/class-wp-sqlite-query-rewriter.php';
 require_once __DIR__ . '/../wp-includes/sqlite/class-wp-sqlite-lexer.php';
@@ -14,11 +20,6 @@
 	define( 'WP_SQLITE_UNSAFE_ENABLE_UNSUPPORTED_VERSIONS', true );
 }
 
-// Configure the test environment.
-error_reporting( E_ALL );
-define( 'FQDB', ':memory:' );
-define( 'FQDBDIR', __DIR__ . '/../testdb' );
-
 // Polyfill WPDB globals.
 $GLOBALS['table_prefix'] = 'wptests_';
 $GLOBALS['wpdb']         = new class() {

wp-includes/sqlite-ast/class-wp-sqlite-connection.php

@@ -63,6 +63,7 @@ class WP_SQLite_Connection {
 	 *     @type int|null    $timeout      Optional. SQLite timeout in seconds.
 	 *                                     The time to wait for a writable lock.
 	 *     @type string|null $journal_mode Optional. SQLite journal mode.
+	 *     @type int|null $application_id  Optional. SQLite application ID.
 	 * }
 	 *
 	 * @throws InvalidArgumentException When some connection options are invalid.
@@ -96,6 +97,10 @@ public function __construct( array $options ) {
 		if ( $journal_mode && in_array( $journal_mode, self::SQLITE_JOURNAL_MODES, true ) ) {
 			$this->query( 'PRAGMA journal_mode = ' . $journal_mode );
 		}
+
+		if ( isset( $options['application_id'] ) ) {
+			$this->query( 'PRAGMA application_id = ' . (int) $options['application_id'] );
+		}
 	}
 
 	/**

wp-includes/sqlite/class-wp-sqlite-db.php

@@ -30,6 +30,13 @@ class WP_SQLite_DB extends wpdb {
 	 */
 	private $allow_unsafe_unquoted_parameters = true;
 
+	/**
+	 * The application ID for the SQLite database.
+	 *
+	 * @see https://www.sqlite.org/pragma.html#pragma_application_id
+	 */
+	const SQLITE_DB_APPLICATION_ID = 3948349;
+
 	/**
 	 * Connects to the SQLite database.
 	 *
@@ -306,6 +313,28 @@ public function db_connect( $allow_bail = true ) {
 		if ( isset( $GLOBALS['@pdo'] ) ) {
 			$pdo = $GLOBALS['@pdo'];
 		}
+
+		// Migrate the database file from the legacy default name (".ht.sqlite") to
+		// the new default name (".ht.sqlite.php"). This only runs when using the
+		// default file name and the new file does not already exist.
+		if ( ! defined( 'DB_FILE' ) && ! file_exists( FQDB ) ) {
+			$old_db_path = FQDBDIR . '.ht.sqlite';
+
+			if ( file_exists( $old_db_path ) ) {
+				if ( ! rename( $old_db_path, FQDB ) ) {
+					wp_die( 'Failed to rename database file.', 'Error!' );
+				}
+
+				foreach ( array( '-wal', '-shm' ) as $suffix ) {
+					if ( file_exists( $old_db_path . $suffix ) ) {
+						if ( ! rename( $old_db_path . $suffix, FQDB . $suffix ) ) {
+							wp_die( 'Failed to rename database file.', 'Error!' );
+						}
+					}
+				}
+			}
+		}
+
 		if ( defined( 'WP_SQLITE_AST_DRIVER' ) && WP_SQLITE_AST_DRIVER ) {
 			if ( null === $this->dbname || '' === $this->dbname ) {
 				$this->bail(
@@ -321,9 +350,10 @@ public function db_connect( $allow_bail = true ) {
 			try {
 				$connection      = new WP_SQLite_Connection(
 					array(
-						'pdo'          => $pdo,
-						'path'         => FQDB,
-						'journal_mode' => defined( 'SQLITE_JOURNAL_MODE' ) ? SQLITE_JOURNAL_MODE : null,
+						'pdo'            => $pdo,
+						'path'           => FQDB,
+						'journal_mode'   => defined( 'SQLITE_JOURNAL_MODE' ) ? SQLITE_JOURNAL_MODE : null,
+						'application_id' => self::SQLITE_DB_APPLICATION_ID,
 					)
 				);
 				$this->dbh       = new WP_SQLite_Driver( $connection, $this->dbname );