Function serveFile

http/file_server.ts:183–338

(
  req: Request,
  filePath: string,
  options?: ServeFileOptions,
)

 * @returns A response for the request.
 */
export async function serveFile(
  req: Request,
  filePath: string,
  options?: ServeFileOptions,
): Promise<Response> {
  await req.body?.cancel();

  if (req.method !== METHOD.Get && req.method !== METHOD.Head) {
    return createStandardResponse(STATUS_CODE.MethodNotAllowed);
  }

  let { etagAlgorithm: algorithm = "SHA-256", fileInfo } = options ?? {};

  try {
    fileInfo ??= await Deno.stat(filePath);
  } catch (error) {
    if (error instanceof Deno.errors.NotFound) {
      return createStandardResponse(STATUS_CODE.NotFound);
    } else {
      throw error;
    }
  }

  if (fileInfo.isDirectory) {
    return createStandardResponse(STATUS_CODE.NotFound);
  }

  const headers = createBaseHeaders();

  const etag = fileInfo.mtime
    ? await eTag(fileInfo, { algorithm })
    : await HASHED_DENO_DEPLOYMENT_ID;

  // Set last modified header if last modification timestamp is available
  if (fileInfo.mtime) {
    headers.set(HEADER.LastModified, fileInfo.mtime.toUTCString());
  }
  if (etag) {
    headers.set(HEADER.ETag, etag);
  }

  // Set mime-type using the file extension in filePath
  const contentTypeValue = contentType(extname(filePath));
  if (contentTypeValue) {
    headers.set(HEADER.ContentType, contentTypeValue);
  }
  const fileSize = fileInfo.size;

  if (req.method === METHOD.Head) {
    // Set content length
    headers.set(HEADER.ContentLength, `${fileSize}`);

    const status = STATUS_CODE.OK;
    return new Response(null, {
      status,
      statusText: STATUS_TEXT[status],
      headers,
    });