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std/fs/exists.ts

Deno standard library
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// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
/** Options for {@linkcode exists} and {@linkcode existsSync.} */export interface ExistsOptions { /** * When `true`, will check if the path is readable by the user as well. * @default {false} */ isReadable?: boolean; /** * When `true`, will check if the path is a directory as well. * Directory symlinks are included. * @default {false} */ isDirectory?: boolean; /** * When `true`, will check if the path is a file as well. * File symlinks are included. * @default {false} */ isFile?: boolean;}
/** * Test whether or not the given path exists by checking with the file system. Please consider to check if the path is readable and either a file or a directory by providing additional `options`: * * ```ts * import { exists } from "https://deno.land/std@$STD_VERSION/fs/mod.ts"; * const isReadableDir = await exists("./foo", { * isReadable: true, * isDirectory: true * }); * const isReadableFile = await exists("./bar", { * isReadable: true, * isFile: true * }); * ``` * * Note: Do not use this function if performing a check before another operation on that file. Doing so creates a race condition. Instead, perform the actual file operation directly. * * Bad: * ```ts * import { exists } from "https://deno.land/std@$STD_VERSION/fs/mod.ts"; * * if (await exists("./foo")) { * await Deno.remove("./foo"); * } * ``` * * Good: * ```ts * // Notice no use of exists * try { * await Deno.remove("./foo", { recursive: true }); * } catch (error) { * if (!(error instanceof Deno.errors.NotFound)) { * throw error; * } * // Do nothing... * } * ``` * @see https://en.wikipedia.org/wiki/Time-of-check_to_time-of-use */export async function exists( path: string | URL, options?: ExistsOptions,): Promise<boolean> { try { const stat = await Deno.stat(path); if ( options && (options.isReadable || options.isDirectory || options.isFile) ) { if (options.isDirectory && options.isFile) { throw new TypeError( "ExistsOptions.options.isDirectory and ExistsOptions.options.isFile must not be true together.", ); } if ( (options.isDirectory && !stat.isDirectory) || (options.isFile && !stat.isFile) ) { return false; } if (options.isReadable) { if (stat.mode === null) { return true; // Exclusive on Non-POSIX systems } if (Deno.uid() === stat.uid) { return (stat.mode & 0o400) === 0o400; // User is owner and can read? } else if (Deno.gid() === stat.gid) { return (stat.mode & 0o040) === 0o040; // User group is owner and can read? } return (stat.mode & 0o004) === 0o004; // Others can read? } } return true; } catch (error) { if (error instanceof Deno.errors.NotFound) { return false; } if (error instanceof Deno.errors.PermissionDenied) { if ( (await Deno.permissions.query({ name: "read", path })).state === "granted" ) { // --allow-read not missing return !options?.isReadable; // PermissionDenied was raised by file system, so the item exists, but can't be read } } throw error; }}
/** * Test whether or not the given path exists by checking with the file system. Please consider to check if the path is readable and either a file or a directory by providing additional `options`: * * ```ts * import { existsSync } from "https://deno.land/std@$STD_VERSION/fs/mod.ts"; * const isReadableDir = existsSync("./foo", { * isReadable: true, * isDirectory: true * }); * const isReadableFile = existsSync("./bar", { * isReadable: true, * isFile: true * }); * ``` * * Note: do not use this function if performing a check before another operation on that file. Doing so creates a race condition. Instead, perform the actual file operation directly. * * Bad: * ```ts * import { existsSync } from "https://deno.land/std@$STD_VERSION/fs/mod.ts"; * * if (existsSync("./foo")) { * Deno.removeSync("./foo"); * } * ``` * * Good: * ```ts * // Notice no use of existsSync * try { * Deno.removeSync("./foo", { recursive: true }); * } catch (error) { * if (!(error instanceof Deno.errors.NotFound)) { * throw error; * } * // Do nothing... * } * ``` * @see https://en.wikipedia.org/wiki/Time-of-check_to_time-of-use */export function existsSync( path: string | URL, options?: ExistsOptions,): boolean { try { const stat = Deno.statSync(path); if ( options && (options.isReadable || options.isDirectory || options.isFile) ) { if (options.isDirectory && options.isFile) { throw new TypeError( "ExistsOptions.options.isDirectory and ExistsOptions.options.isFile must not be true together.", ); } if ( (options.isDirectory && !stat.isDirectory) || (options.isFile && !stat.isFile) ) { return false; } if (options.isReadable) { if (stat.mode === null) { return true; // Exclusive on Non-POSIX systems } if (Deno.uid() === stat.uid) { return (stat.mode & 0o400) === 0o400; // User is owner and can read? } else if (Deno.gid() === stat.gid) { return (stat.mode & 0o040) === 0o040; // User group is owner and can read? } return (stat.mode & 0o004) === 0o004; // Others can read? } } return true; } catch (error) { if (error instanceof Deno.errors.NotFound) { return false; } if (error instanceof Deno.errors.PermissionDenied) { if ( Deno.permissions.querySync({ name: "read", path }).state === "granted" ) { // --allow-read not missing return !options?.isReadable; // PermissionDenied was raised by file system, so the item exists, but can't be read } } throw error; }}