Add ME01/SA01 support

package.json

@@ -57,6 +57,11 @@
 			"require": "./dist/msbt.js",
 			"types": "./dist/msbt.d.ts"
 		},
+		"./me01": {
+			"import": "./dist/me01.js",
+			"require": "./dist/me01.js",
+			"types": "./dist/me01.d.ts"
+		},
 		"./smdh": {
 			"import": "./dist/smdh.js",
 			"require": "./dist/smdh.js",

src/index.ts

@@ -9,6 +9,9 @@ export * from '@/certificate';
 export { default as CIA } from '@/cia';
 export * from '@/cia';
 
+export { default as ME01 } from '@/me01';
+export * from '@/me01';
+
 export { default as MSBT } from '@/msbt';
 export * from '@/msbt';
 

src/me01.ts

@@ -0,0 +1,170 @@
+import FileStream from '@/file-stream';
+
+const ME01_MAGIC = Buffer.from('ME01');
+const SA01_MAGIC = Buffer.from('SA01');
+
+/**
+ * ME01 represents a data archive file. These files can have the magic `ME01` or `SA01`
+ */
+export default class ME01 {
+	private stream: FileStream;
+
+	/**
+	 * Files in the archive
+	 */
+	public files: { name: string; data: Buffer; }[] = [];
+
+	/**
+	 * Parses the ME01 from the provided `fdOrPath`
+	 *
+	 * @param fdOrPath - Either an open `fd` or a path to a file on disk
+	 */
+	public parseFromFile(fdOrPath: number | string): void {
+		this.stream = new FileStream(fdOrPath);
+		this.parse();
+	}
+
+	/**
+	 * Parses the ME01 from the provided `buffer`
+	 *
+	 * @param buffer - ME01 data buffer
+	 */
+	public parseFromBuffer(buffer: Buffer): void {
+		this.stream = new FileStream(buffer);
+		this.parse();
+	}
+
+	/**
+	 * Parses the ME01 from the provided string
+	 *
+	 * Calls `parseFromBuffer` internally
+	 *
+	 * @param base64 - Base64 encoded ME01 data
+	 */
+	public parseFromString(base64: string): void {
+		this.parseFromBuffer(Buffer.from(base64, 'base64'));
+	}
+
+	/**
+	 * Parses the ME01 from an existing file stream
+	 *
+	 * @param stream - An existing file stream
+	 */
+	public parseFromFileStream(stream: FileStream): void {
+		this.stream = stream;
+		this.parse();
+	}
+
+	/**
+	 * Creates a new instance of `ME01` and
+	 * parses the ME01 from the provided `fdOrPath`
+	 *
+	 * @param fdOrPath - Either an open `fd` or a path to a file on disk
+	 */
+	public static fromFile(fdOrPath: number | string): ME01 {
+		const me01 = new ME01();
+		me01.parseFromFile(fdOrPath);
+
+		return me01;
+	}
+
+	/**
+	 * Creates a new instance of `ME01` and
+	 * parses the ME01 from the provided `buffer`
+	 *
+	 * @param buffer - ME01 data buffer
+	 */
+	public static fromBuffer(buffer: Buffer): ME01 {
+		const me01 = new ME01();
+		me01.parseFromBuffer(buffer);
+
+		return me01;
+	}
+
+	/**
+	 * Creates a new instance of `ME01` and
+	 * parses the ME01 from the provided string
+	 *
+	 * Calls `parseFromBuffer` internally
+	 *
+	 * @param base64 - Base64 encoded ME01 data
+	 */
+	public static fromString(base64: string): ME01 {
+		const me01 = new ME01();
+		me01.parseFromString(base64);
+
+		return me01;
+	}
+
+	/**
+	 * Creates a new instance of `ME01` and
+	 * parses the ME01 from an existing file stream
+	 *
+	 * @param stream - An existing file stream
+	 */
+	public static fromFileStream(stream: FileStream): ME01 {
+		const me01 = new ME01();
+		me01.parseFromFileStream(stream);
+
+		return me01;
+	}
+
+	/**
+	 * Parses the ME01 from the input source provided at instantiation
+	 */
+	public parse(): void {
+		// * I couldn't find any docs or wikis about this file format,
+		// * so I'm basing this mostly off Switch-Toolbox
+		// * https://github.com/KillzXGaming/Switch-Toolbox/blob/43c847c85900273dc4ff0366fad8ef29f32db4bd/File_Format_Library/FileFormats/Archives/ME01.cs
+
+		const magic = this.stream.readBytes(0x4);
+
+		if (!ME01_MAGIC.equals(magic) && !SA01_MAGIC.equals(magic)) {
+			throw new Error('Invalid ME01 magic');
+		}
+
+		if (SA01_MAGIC.equals(magic)) {
+			this.stream.bom = 'be';
+		}
+
+		const fileCount = this.stream.readUInt32();
+		const fileDataOffset = this.stream.readUInt32(); // * Switch-Toolbox names this "Alignment"?
+
+		const dataOffsets = Array.from({ length: fileCount }, () => this.stream.readUInt32());
+		const dataSizes = Array.from({ length: fileCount }, () => this.stream.readUInt32());
+		const fileNames: string[] = [];
+
+		// * Switch-Toolbox reads this slightly differently. It reads the padding to find the
+		// * next offset, but it seems like they're always in 0x80 length chunks
+		for (let i = 0; i < fileCount; i++) {
+			const block = this.stream.readBytes(0x80);
+			const fileName = block.toString().split('\0')[0];
+
+			fileNames.push(fileName);
+		}
+
+		// * Switch-Toolbox does this slightly differently. It reads the padding to find the
+		// * file data offset, but this seems like it can be skipped by just jumping right to
+		// * value it calls "Alignment"? Doing so saves reads
+		this.stream.seek(fileDataOffset);
+
+		// * Switch-Toolbox reads this slightly differently. It reads the padding to find the
+		// * next offset, but this seems like it can be skipped by just jumping right to the
+		// * next file, saving reads
+		for (let i = 0; i < fileCount; i++) {
+
+			const fileOffset = dataOffsets[i];
+			const fileName = fileNames[i];
+			const fileSize = dataSizes[i];
+
+			this.stream.seek(fileDataOffset + fileOffset);
+
+			const fileData = this.stream.readBytes(fileSize);
+
+			this.files.push({
+				name: fileName,
+				data: fileData
+			});
+		}
+	}
+}