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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.import { Buffer } from "../buffer.ts";import { assert } from "../../testing/asserts.ts";import {  ERR_INVALID_ARG_TYPE,  ERR_INVALID_ARG_VALUE,} from "../internal/errors.ts";
type readOptions = {  buffer: Buffer | Uint8Array;  offset: number;  length: number;  position: number | null;};
type readSyncOptions = {  offset: number;  length: number;  position: number | null;};
type BinaryCallback = (  err: Error | null,  bytesRead: number | null,  data?: Buffer,) => void;type Callback = BinaryCallback;
export function read(fd: number, callback: Callback): void;export function read(  fd: number,  options: readOptions,  callback: Callback,): void;export function read(  fd: number,  buffer: Buffer | Uint8Array,  offset: number,  length: number,  position: number | null,  callback: Callback,): void;export function read(  fd: number,  optOrBufferOrCb?: Buffer | Uint8Array | readOptions | Callback,  offsetOrCallback?: number | Callback,  length?: number,  position?: number | null,  callback?: Callback,) {  let cb: Callback | undefined;  let offset = 0,    buffer: Buffer | Uint8Array;
  if (typeof fd !== "number") {    throw new ERR_INVALID_ARG_TYPE("fd", "number", fd);  }
  if (length == null) {    length = 0;  }
  if (typeof offsetOrCallback === "function") {    cb = offsetOrCallback;  } else if (typeof optOrBufferOrCb === "function") {    cb = optOrBufferOrCb;  } else {    offset = offsetOrCallback as number;    cb = callback;  }
  if (!cb) throw new ERR_INVALID_ARG_TYPE("cb", "Callback", cb);
  if (    optOrBufferOrCb instanceof Buffer || optOrBufferOrCb instanceof Uint8Array  ) {    buffer = optOrBufferOrCb;  } else if (typeof optOrBufferOrCb === "function") {    offset = 0;    buffer = Buffer.alloc(16384);    length = buffer.byteLength;    position = null;  } else {    const opt = optOrBufferOrCb as readOptions;    offset = opt.offset ?? 0;    buffer = opt.buffer ?? Buffer.alloc(16384);    length = opt.length ?? buffer.byteLength;    position = opt.position ?? null;  }
  assert(offset >= 0, "offset should be greater or equal to 0");  assert(    offset + length <= buffer.byteLength,    `buffer doesn't have enough data: byteLength = ${buffer.byteLength}, offset + length = ${      offset + length    }`,  );
  if (buffer.byteLength == 0) {    throw new ERR_INVALID_ARG_VALUE(      "buffer",      buffer,      "is empty and cannot be written",    );  }
  let err: Error | null = null,    numberOfBytesRead: number | null = null;
  try {    let currentPosition = 0;    if (typeof position === "number" && position >= 0) {      currentPosition = Deno.seekSync(fd, 0, Deno.SeekMode.Current);      Deno.seekSync(fd, position, Deno.SeekMode.Start);    }
    numberOfBytesRead = Deno.readSync(fd, buffer);
    if (typeof position === "number" && position >= 0) {      Deno.seekSync(fd, currentPosition, Deno.SeekMode.Start);    }  } catch (error) {    err = error instanceof Error ? error : new Error("[non-error thrown]");  }
  if (err) {    (callback as (err: Error) => void)(err);  } else {    const data = Buffer.from(buffer.buffer, offset, length);    cb(null, numberOfBytesRead ?? 0, data);  }
  return;}
export function readSync(  fd: number,  buffer: Buffer | Uint8Array,  offset: number,  length: number,  position: number | null,): number;export function readSync(  fd: number,  buffer: Buffer | Uint8Array,  opt: readSyncOptions,): number;export function readSync(  fd: number,  buffer: Buffer | Uint8Array,  offsetOrOpt?: number | readSyncOptions,  length?: number,  position?: number | null,): number {  let offset = 0;
  if (length == null) {    length = 0;  }
  if (buffer.byteLength == 0) {    throw new ERR_INVALID_ARG_VALUE(      "buffer",      buffer,      "is empty and cannot be written",    );  }
  if (typeof offsetOrOpt === "number") {    offset = offsetOrOpt;  } else {    const opt = offsetOrOpt as readSyncOptions;    offset = opt.offset ?? 0;    length = opt.length ?? buffer.byteLength;    position = opt.position ?? null;  }
  assert(offset >= 0, "offset should be greater or equal to 0");  assert(    offset + length <= buffer.byteLength,    `buffer doesn't have enough data: byteLength = ${buffer.byteLength}, offset + length = ${      offset + length    }`,  );
  let currentPosition = 0;  if (typeof position === "number" && position >= 0) {    currentPosition = Deno.seekSync(fd, 0, Deno.SeekMode.Current);    Deno.seekSync(fd, position, Deno.SeekMode.Start);  }
  const numberOfBytesRead = Deno.readSync(fd, buffer);
  if (typeof position === "number" && position >= 0) {    Deno.seekSync(fd, currentPosition, Deno.SeekMode.Start);  }
  return numberOfBytesRead ?? 0;}