MySQL Proxy for SQLite

.gitattributes

@@ -8,6 +8,7 @@ phpunit.xml.dist export-ignore
 wp-setup.sh export-ignore
 /.github export-ignore
 /grammar-tools export-ignore
+/packages export-ignore
 /tests export-ignore
 /wp-includes/sqlite/class-wp-sqlite-crosscheck-db.php export-ignore
 /wordpress export-ignore

.github/workflows/mysql-proxy-tests.yml

@@ -0,0 +1,33 @@
+name: MySQL Proxy Tests
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+
+jobs:
+  test:
+    name: MySQL Proxy Tests
+    runs-on: ubuntu-latest
+    timeout-minutes: 20
+
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+
+      - name: Set up PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: '7.4'
+
+      - name: Install Composer dependencies
+        uses: ramsey/composer-install@v3
+        with:
+          ignore-cache: "yes"
+          composer-options: "--optimize-autoloader"
+          working-directory: packages/wp-mysql-proxy
+
+      - name: Run MySQL Proxy tests
+        run: composer run test
+        working-directory: packages/wp-mysql-proxy

packages/wp-mysql-proxy/README.md

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+# WP MySQL Proxy
+A MySQL proxy that bridges the MySQL wire protocol to a PDO-like interface.
+
+This is a zero-dependency, pure PHP implementation of a MySQL proxy that acts as
+a MySQL server, accepts MySQL-native commands, and executes them using a configurable
+PDO-like driver. This allows MySQL-compatible clients to connect and run queries
+against alternative database backends over the MySQL wire protocol.
+
+Combined with the **WP SQLite Driver**, this allows MySQL-based projects to run
+on SQLite.
+
+## Usage
+
+### CLI:
+
+```bash
+$ php mysql-proxy.php [--database <path/to/db.sqlite>] [--port <port>]
+
+Options:
+  -h, --help            Show this help message and exit.
+  -d, --database=<path> The path to the SQLite database file. Default: :memory:
+  -p, --port=<port>     The port to listen on. Default: 3306
+```
+
+### PHP:
+```php
+use WP_MySQL_Proxy\MySQL_Proxy;
+use WP_MySQL_Proxy\Adapter\SQLite_Adapter;
+
+require_once __DIR__ . '/vendor/autoload.php';
+
+$proxy = new MySQL_Proxy(
+	new SQLite_Adapter( $db_path ),
+	array( 'port' => $port )
+);
+$proxy->start();
+```

packages/wp-mysql-proxy/bin/wp-mysql-proxy.php

@@ -0,0 +1,46 @@
+<?php declare( strict_types = 1 );
+
+use WP_MySQL_Proxy\MySQL_Proxy;
+use WP_MySQL_Proxy\Adapter\SQLite_Adapter;
+
+require_once __DIR__ . '/../vendor/autoload.php';
+
+define( 'WP_SQLITE_AST_DRIVER', true );
+
+// Process CLI arguments:
+$shortopts = 'h:d:p';
+$longopts  = array( 'help', 'database:', 'port:' );
+$opts      = getopt( $shortopts, $longopts );
+
+$help = <<<USAGE
+Usage: php mysql-proxy.php [--database <path/to/db.sqlite>] [--port <port>]
+
+Options:
+  -h, --help            Show this help message and exit.
+  -d, --database=<path> The path to the SQLite database file. Default: :memory:
+  -p, --port=<port>     The port to listen on. Default: 3306
+
+USAGE;
+
+// Help.
+if ( isset( $opts['h'] ) || isset( $opts['help'] ) ) {
+	fwrite( STDERR, $help );
+	exit( 0 );
+}
+
+// Database path.
+$db_path = $opts['d'] ?? $opts['database'] ?? ':memory:';
+
+// Port.
+$port = (int) ( $opts['p'] ?? $opts['port'] ?? 3306 );
+if ( $port < 1 || $port > 65535 ) {
+	fwrite( STDERR, "Error: --port must be an integer between 1 and 65535. Use --help for more information.\n" );
+	exit( 1 );
+}
+
+// Start the MySQL proxy.
+$proxy = new MySQL_Proxy(
+	new SQLite_Adapter( $db_path ),
+	array( 'port' => $port )
+);
+$proxy->start();

packages/wp-mysql-proxy/composer.json

@@ -0,0 +1,22 @@
+{
+    "name": "wordpress/wp-mysql-proxy",
+    "type": "library",
+	"bin": [
+		"bin/wp-mysql-proxy.php"
+	],
+	"scripts": {
+		"test": "phpunit"
+	},
+    "require-dev": {
+        "phpunit/phpunit": "^8.5",
+        "symfony/process": "^5.4"
+    },
+	"autoload": {
+		"classmap": [
+			"src/"
+		],
+		"files": [
+			"../../php-polyfills.php"
+		]
+	}
+}

packages/wp-mysql-proxy/phpunit.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<phpunit bootstrap="tests/bootstrap/bootstrap.php" colors="true" stopOnFailure="false">
+    <testsuites>
+        <testsuite name="WP MySQL Proxy Test Suite">
+            <directory>tests/</directory>
+        </testsuite>
+    </testsuites>
+</phpunit>

packages/wp-mysql-proxy/src/Adapter/class-adapter.php

@@ -0,0 +1,9 @@
+<?php declare( strict_types = 1 );
+
+namespace WP_MySQL_Proxy\Adapter;
+
+use WP_MySQL_Proxy\MySQL_Result;
+
+interface Adapter {
+	public function handle_query( string $query ): MySQL_Result;
+}

packages/wp-mysql-proxy/src/Adapter/class-sqlite-adapter.php

@@ -0,0 +1,122 @@
+<?php declare( strict_types = 1 );
+
+namespace WP_MySQL_Proxy\Adapter;
+
+use PDOException;
+use Throwable;
+use WP_MySQL_Proxy\MySQL_Result;
+use WP_SQLite_Connection;
+use WP_SQLite_Driver;
+use WP_MySQL_Proxy\MySQL_Protocol;
+
+define( 'SQLITE_DRIVER_PATH', __DIR__ . '/../../../..' );
+
+require_once SQLITE_DRIVER_PATH . '/version.php';
+require_once SQLITE_DRIVER_PATH . '/wp-includes/parser/class-wp-parser-grammar.php';
+require_once SQLITE_DRIVER_PATH . '/wp-includes/parser/class-wp-parser.php';
+require_once SQLITE_DRIVER_PATH . '/wp-includes/parser/class-wp-parser-node.php';
+require_once SQLITE_DRIVER_PATH . '/wp-includes/parser/class-wp-parser-token.php';
+require_once SQLITE_DRIVER_PATH . '/wp-includes/mysql/class-wp-mysql-token.php';
+require_once SQLITE_DRIVER_PATH . '/wp-includes/mysql/class-wp-mysql-lexer.php';
+require_once SQLITE_DRIVER_PATH . '/wp-includes/mysql/class-wp-mysql-parser.php';
+require_once SQLITE_DRIVER_PATH . '/wp-includes/sqlite/class-wp-sqlite-pdo-user-defined-functions.php';
+require_once SQLITE_DRIVER_PATH . '/wp-includes/sqlite-ast/class-wp-sqlite-connection.php';
+require_once SQLITE_DRIVER_PATH . '/wp-includes/sqlite-ast/class-wp-sqlite-configurator.php';
+require_once SQLITE_DRIVER_PATH . '/wp-includes/sqlite-ast/class-wp-sqlite-driver.php';
+require_once SQLITE_DRIVER_PATH . '/wp-includes/sqlite-ast/class-wp-sqlite-driver-exception.php';
+require_once SQLITE_DRIVER_PATH . '/wp-includes/sqlite-ast/class-wp-sqlite-information-schema-builder.php';
+require_once SQLITE_DRIVER_PATH . '/wp-includes/sqlite-ast/class-wp-sqlite-information-schema-exception.php';
+require_once SQLITE_DRIVER_PATH . '/wp-includes/sqlite-ast/class-wp-sqlite-information-schema-reconstructor.php';
+
+class SQLite_Adapter implements Adapter {
+	/** @var WP_SQLite_Driver */
+	private $sqlite_driver;
+
+	public function __construct( $sqlite_database_path ) {
+		define( 'FQDB', $sqlite_database_path );
+		define( 'FQDBDIR', dirname( FQDB ) . '/' );
+
+		$this->sqlite_driver = new WP_SQLite_Driver(
+			new WP_SQLite_Connection( array( 'path' => $sqlite_database_path ) ),
+			'sqlite_database'
+		);
+	}
+
+	public function handle_query( string $query ): MySQL_Result {
+		$affected_rows  = 0;
+		$last_insert_id = null;
+		$columns        = array();
+		$rows           = array();
+
+		try {
+			$return_value   = $this->sqlite_driver->query( $query );
+			$last_insert_id = $this->sqlite_driver->get_insert_id() ?? null;
+			if ( is_numeric( $return_value ) ) {
+				$affected_rows = (int) $return_value;
+			} elseif ( is_array( $return_value ) ) {
+				$rows = $return_value;
+			}
+			if ( $this->sqlite_driver->get_last_column_count() > 0 ) {
+				$columns = $this->computeColumnInfo();
+			}
+			return MySQL_Result::from_data( $affected_rows, $last_insert_id, $columns, $rows ?? array() );
+		} catch ( Throwable $e ) {
+			$error_info = $e->errorInfo ?? null; // phpcs:ignore WordPress.NamingConventions.ValidVariableName.UsedPropertyNotSnakeCase
+			if ( $e instanceof PDOException && $error_info ) {
+				return MySQL_Result::from_error( $error_info[0], $error_info[1], $error_info[2] );
+			}
+			return MySQL_Result::from_error( 'HY000', 1105, $e->getMessage() ?? 'Unknown error' );
+		}
+	}
+
+	public function computeColumnInfo() {
+		$columns = array();
+
+		$column_meta = $this->sqlite_driver->get_last_column_meta();
+
+		$types = array(
+			'DECIMAL'     => MySQL_Protocol::FIELD_TYPE_DECIMAL,
+			'TINY'        => MySQL_Protocol::FIELD_TYPE_TINY,
+			'SHORT'       => MySQL_Protocol::FIELD_TYPE_SHORT,
+			'LONG'        => MySQL_Protocol::FIELD_TYPE_LONG,
+			'FLOAT'       => MySQL_Protocol::FIELD_TYPE_FLOAT,
+			'DOUBLE'      => MySQL_Protocol::FIELD_TYPE_DOUBLE,
+			'NULL'        => MySQL_Protocol::FIELD_TYPE_NULL,
+			'TIMESTAMP'   => MySQL_Protocol::FIELD_TYPE_TIMESTAMP,
+			'LONGLONG'    => MySQL_Protocol::FIELD_TYPE_LONGLONG,
+			'INT24'       => MySQL_Protocol::FIELD_TYPE_INT24,
+			'DATE'        => MySQL_Protocol::FIELD_TYPE_DATE,
+			'TIME'        => MySQL_Protocol::FIELD_TYPE_TIME,
+			'DATETIME'    => MySQL_Protocol::FIELD_TYPE_DATETIME,
+			'YEAR'        => MySQL_Protocol::FIELD_TYPE_YEAR,
+			'NEWDATE'     => MySQL_Protocol::FIELD_TYPE_NEWDATE,
+			'VARCHAR'     => MySQL_Protocol::FIELD_TYPE_VARCHAR,
+			'BIT'         => MySQL_Protocol::FIELD_TYPE_BIT,
+			'NEWDECIMAL'  => MySQL_Protocol::FIELD_TYPE_NEWDECIMAL,
+			'ENUM'        => MySQL_Protocol::FIELD_TYPE_ENUM,
+			'SET'         => MySQL_Protocol::FIELD_TYPE_SET,
+			'TINY_BLOB'   => MySQL_Protocol::FIELD_TYPE_TINY_BLOB,
+			'MEDIUM_BLOB' => MySQL_Protocol::FIELD_TYPE_MEDIUM_BLOB,
+			'LONG_BLOB'   => MySQL_Protocol::FIELD_TYPE_LONG_BLOB,
+			'BLOB'        => MySQL_Protocol::FIELD_TYPE_BLOB,
+			'VAR_STRING'  => MySQL_Protocol::FIELD_TYPE_VAR_STRING,
+			'STRING'      => MySQL_Protocol::FIELD_TYPE_STRING,
+			'GEOMETRY'    => MySQL_Protocol::FIELD_TYPE_GEOMETRY,
+		);
+
+		foreach ( $column_meta as $column ) {
+			$type = $types[ $column['native_type'] ] ?? null;
+			if ( null === $type ) {
+				throw new Exception( 'Unknown column type: ' . $column['native_type'] );
+			}
+			$columns[] = array(
+				'name'     => $column['name'],
+				'length'   => $column['len'],
+				'type'     => $type,
+				'flags'    => 129,
+				'decimals' => $column['precision'],
+			);
+		}
+		return $columns;
+	}
+}