1.0.34

src/lib/server/tar-extract.ts

@@ -0,0 +1,64 @@
+/**
+ * Single-file tar extraction for raw downloads (#1180).
+ *
+ * Docker's /archive endpoint always wraps file contents in a USTAR tar.
+ * When the user picks the "no archive" download format and the path is a
+ * regular file, we strip the wrapper and emit the bytes verbatim.
+ *
+ * Only handles the first regular-file entry — the caller has already
+ * guaranteed (via stat) that the requested path is a single file, so the
+ * tar contains exactly one entry.
+ */
+
+/**
+ * Extract the bytes of the first regular file entry in a USTAR tar.
+ * Returns the file content as a Uint8Array.
+ *
+ * Throws when no regular file entry is found (e.g. the tar contained only
+ * a directory header) — that's an unexpected state, since the caller is
+ * supposed to have already verified the path points to a file.
+ */
+export function extractFirstFileFromTar(tarData: Uint8Array): Uint8Array {
+	let offset = 0;
+	while (offset + 512 <= tarData.length) {
+		const header = tarData.subarray(offset, offset + 512);
+
+		// Two consecutive zero blocks mark end-of-archive.
+		if (isZeroBlock(header)) break;
+
+		const name = readString(header, 0, 100);
+		const sizeOctal = readString(header, 124, 12).trim();
+		const size = sizeOctal ? parseInt(sizeOctal, 8) : 0;
+		const typeFlag = header[156];
+
+		// Regular file: typeflag '0' (0x30) or NUL (0x00, legacy)
+		const isRegularFile = typeFlag === 0x30 || typeFlag === 0x00;
+
+		if (isRegularFile && name && size >= 0) {
+			const start = offset + 512;
+			const end = start + size;
+			if (end > tarData.length) {
+				throw new Error('Truncated tar archive');
+			}
+			return tarData.subarray(start, end);
+		}
+
+		// Skip header + content (padded to 512-byte boundary)
+		offset += 512 + Math.ceil(size / 512) * 512;
+	}
+	throw new Error('No regular file entry found in tar archive');
+}
+
+function isZeroBlock(block: Uint8Array): boolean {
+	for (let i = 0; i < block.length; i++) {
+		if (block[i] !== 0) return false;
+	}
+	return true;
+}
+
+function readString(buf: Uint8Array, offset: number, length: number): string {
+	let end = offset;
+	const limit = offset + length;
+	while (end < limit && buf[end] !== 0) end++;
+	return new TextDecoder('utf-8').decode(buf.subarray(offset, end));
+}