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// Copyright 2018-2022 the Deno authors. All rights reserved. MIT license.import {  O_APPEND,  O_CREAT,  O_EXCL,  O_RDONLY,  O_RDWR,  O_TRUNC,  O_WRONLY,} from "./_fs_constants.ts";import { validateFunction } from "../internal/validators.mjs";import type { ErrnoException } from "../_global.d.ts";import {  BinaryEncodings,  Encodings,  notImplemented,  TextEncodings,} from "../_utils.ts";
export type CallbackWithError = (err: ErrnoException | null) => void;
export interface FileOptions {  encoding?: Encodings;  flag?: string;  signal?: AbortSignal;}
export type TextOptionsArgument =  | TextEncodings  | ({ encoding: TextEncodings } & FileOptions);export type BinaryOptionsArgument =  | BinaryEncodings  | ({ encoding: BinaryEncodings } & FileOptions);export type FileOptionsArgument = Encodings | FileOptions;
export interface WriteFileOptions extends FileOptions {  mode?: number;}
export function isFileOptions(  fileOptions: string | WriteFileOptions | undefined,): fileOptions is FileOptions {  if (!fileOptions) return false;
  return (    (fileOptions as FileOptions).encoding != undefined ||    (fileOptions as FileOptions).flag != undefined ||    (fileOptions as FileOptions).signal != undefined ||    (fileOptions as WriteFileOptions).mode != undefined  );}
export function getEncoding(  optOrCallback?:    | FileOptions    | WriteFileOptions    // deno-lint-ignore no-explicit-any    | ((...args: any[]) => any)    | Encodings    | null,): Encodings | null {  if (!optOrCallback || typeof optOrCallback === "function") {    return null;  }
  const encoding = typeof optOrCallback === "string"    ? optOrCallback    : optOrCallback.encoding;  if (!encoding) return null;  return encoding;}
export function checkEncoding(encoding: Encodings | null): Encodings | null {  if (!encoding) return null;
  encoding = encoding.toLowerCase() as Encodings;  if (["utf8", "hex", "base64"].includes(encoding)) return encoding;
  if (encoding === "utf-8") {    return "utf8";  }  if (encoding === "binary") {    return "binary";    // before this was buffer, however buffer is not used in Node    // node -e "require('fs').readFile('../world.txt', 'buffer', console.log)"  }
  const notImplementedEncodings = ["utf16le", "latin1", "ascii", "ucs2"];
  if (notImplementedEncodings.includes(encoding as string)) {    notImplemented(`"${encoding}" encoding`);  }
  throw new Error(`The value "${encoding}" is invalid for option "encoding"`);}
export function getOpenOptions(  flag: string | number | undefined,): Deno.OpenOptions {  if (!flag) {    return { create: true, append: true };  }
  let openOptions: Deno.OpenOptions = {};
  if (typeof flag === "string") {    switch (flag) {      case "a": {        // 'a': Open file for appending. The file is created if it does not exist.        openOptions = { create: true, append: true };        break;      }      case "ax":      case "xa": {        // 'ax', 'xa': Like 'a' but fails if the path exists.        openOptions = { createNew: true, write: true, append: true };        break;      }      case "a+": {        // 'a+': Open file for reading and appending. The file is created if it does not exist.        openOptions = { read: true, create: true, append: true };        break;      }      case "ax+":      case "xa+": {        // 'ax+', 'xa+': Like 'a+' but fails if the path exists.        openOptions = { read: true, createNew: true, append: true };        break;      }      case "r": {        // 'r': Open file for reading. An exception occurs if the file does not exist.        openOptions = { read: true };        break;      }      case "r+": {        // 'r+': Open file for reading and writing. An exception occurs if the file does not exist.        openOptions = { read: true, write: true };        break;      }      case "w": {        // 'w': Open file for writing. The file is created (if it does not exist) or truncated (if it exists).        openOptions = { create: true, write: true, truncate: true };        break;      }      case "wx":      case "xw": {        // 'wx', 'xw': Like 'w' but fails if the path exists.        openOptions = { createNew: true, write: true };        break;      }      case "w+": {        // 'w+': Open file for reading and writing. The file is created (if it does not exist) or truncated (if it exists).        openOptions = { create: true, write: true, truncate: true, read: true };        break;      }      case "wx+":      case "xw+": {        // 'wx+', 'xw+': Like 'w+' but fails if the path exists.        openOptions = { createNew: true, write: true, read: true };        break;      }      case "as":      case "sa": {        // 'as', 'sa': Open file for appending in synchronous mode. The file is created if it does not exist.        openOptions = { create: true, append: true };        break;      }      case "as+":      case "sa+": {        // 'as+', 'sa+': Open file for reading and appending in synchronous mode. The file is created if it does not exist.        openOptions = { create: true, read: true, append: true };        break;      }      case "rs+":      case "sr+": {        // 'rs+', 'sr+': Open file for reading and writing in synchronous mode. Instructs the operating system to bypass the local file system cache.        openOptions = { create: true, read: true, write: true };        break;      }      default: {        throw new Error(`Unrecognized file system flag: ${flag}`);      }    }  } else if (typeof flag === "number") {    if ((flag & O_APPEND) === O_APPEND) {      openOptions.append = true;    }    if ((flag & O_CREAT) === O_CREAT) {      openOptions.create = true;      openOptions.write = true;    }    if ((flag & O_EXCL) === O_EXCL) {      openOptions.createNew = true;      openOptions.read = true;      openOptions.write = true;    }    if ((flag & O_TRUNC) === O_TRUNC) {      openOptions.truncate = true;    }    if ((flag & O_RDONLY) === O_RDONLY) {      openOptions.read = true;    }    if ((flag & O_WRONLY) === O_WRONLY) {      openOptions.write = true;    }    if ((flag & O_RDWR) === O_RDWR) {      openOptions.read = true;      openOptions.write = true;    }  }
  return openOptions;}
export { isUint32 as isFd } from "../internal/validators.mjs";
export function maybeCallback(cb: unknown) {  validateFunction(cb, "cb");
  return cb as CallbackWithError;}
// Ensure that callbacks run in the global context. Only use this function// for callbacks that are passed to the binding layer, callbacks that are// invoked from JS already run in the proper scope.export function makeCallback(  this: unknown,  cb?: (err: Error | null, result?: unknown) => void,) {  validateFunction(cb, "cb");
  return (...args: unknown[]) => Reflect.apply(cb!, this, args);}