std/path/windows/to_namespaced_path.ts

// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
// This module is browser compatible.

import {
  CHAR_BACKWARD_SLASH,
  CHAR_COLON,
  CHAR_DOT,
  CHAR_QUESTION_MARK,
} from "../_common/constants.ts";
import { isWindowsDeviceRoot } from "./_util.ts";
import { resolve } from "./resolve.ts";

/**
 * Resolves path to a namespace path
 *
 * @example Usage
 * ```ts
 * import { toNamespacedPath } from "@std/path/windows/to-namespaced-path";
 * import { assertEquals } from "@std/assert";
 *
 * const namespaced = toNamespacedPath("C:\\foo\\bar");
 * assertEquals(namespaced, "\\\\?\\C:\\foo\\bar");
 * ```
 *
 * @param path The path to resolve to namespaced path
 * @returns The resolved namespaced path
 */
export function toNamespacedPath(path: string): string {
  // Note: this will *probably* throw somewhere.
  if (typeof path !== "string") return path;
  if (path.length === 0) return "";

  const resolvedPath = resolve(path);

  if (resolvedPath.length >= 3) {
    if (resolvedPath.charCodeAt(0) === CHAR_BACKWARD_SLASH) {
      // Possible UNC root

      if (resolvedPath.charCodeAt(1) === CHAR_BACKWARD_SLASH) {
        const code = resolvedPath.charCodeAt(2);
        if (code !== CHAR_QUESTION_MARK && code !== CHAR_DOT) {
          // Matched non-long UNC root, convert the path to a long UNC path
          return `\\\\?\\UNC\\${resolvedPath.slice(2)}`;
        }
      }
    } else if (isWindowsDeviceRoot(resolvedPath.charCodeAt(0))) {
      // Possible device root

      if (
        resolvedPath.charCodeAt(1) === CHAR_COLON &&
        resolvedPath.charCodeAt(2) === CHAR_BACKWARD_SLASH
      ) {
        // Matched device root, convert the path to a long UNC path
        return `\\\\?\\${resolvedPath}`;
      }
    }
  }

  return path;
}