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archived: streaming RAR extractor jsr.io/@mary/rar
jsr
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1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768697071727374757677787980818283848586878889909192/** * @module * * {@link Reader} factories that wrap Node.js runtime APIs. */
import type { FileHandle } from 'node:fs/promises';
import type { Reader } from './types.ts';
/** * creates a reader from a Node.js' FileHandle * @param handle the file handle to read from * @returns a reader for the file */export const fromFileHandle = async (handle: FileHandle): Promise<Reader> => { const totalLength = (await handle.stat()).size;
return { length: totalLength, // deno-lint-ignore require-await async read(offset: number, length?: number): Promise<ReadableStream<Uint8Array<ArrayBuffer>>> { let remaining = length !== undefined ? length : totalLength - offset;
return new ReadableStream<Uint8Array<ArrayBuffer>>({ type: 'bytes', async pull(rawController) { // the underlying source is `type: 'bytes'`, so the runtime // controller is always a byte-stream controller; the // generic-typed parameter just doesn't narrow. const controller = rawController as ReadableByteStreamController;
// when a BYOB reader is waiting, read straight into the // consumer's buffer and skip the per-pull Uint8Array // allocation + queue copy that the default-reader path // pays on every chunk. const byob = controller.byobRequest; // loose `!= null`: Bun yields `undefined` for an absent // byobRequest, not the spec's `null`. if (byob != null) { const view = byob.view as Uint8Array<ArrayBuffer>; const cap = view.byteLength <= remaining ? view.byteLength : remaining; const target = cap === view.byteLength ? view : new Uint8Array(view.buffer, view.byteOffset, cap); const { bytesRead } = await handle.read(target, 0, cap, offset);
if (bytesRead === 0) { byob.respond(0); controller.close(); return; }
remaining -= bytesRead; offset += bytesRead; byob.respond(bytesRead);
if (remaining <= 0) { controller.close(); } return; }
const size = Math.min(controller.desiredSize!, remaining);
const buffer = new Uint8Array(size); const { bytesRead } = await handle.read(buffer, 0, size, offset);
if (bytesRead === 0) { // end of file controller.close(); return; }
if (bytesRead < size) { // partial read, slice the buffer controller.enqueue(buffer.subarray(0, bytesRead)); } else { controller.enqueue(buffer); }
remaining -= bytesRead; offset += bytesRead;
if (remaining <= 0) { controller.close(); return; } }, }, { highWaterMark: 64 * 1024 }); }, };};