getValidRootDirectories (roots-utils.ts)

Resolves and validates filesystem root directories from URI specifications.

import { promises as fs, type Stats } from 'fs';
import path from 'path';
import os from 'os';
import { normalizePath } from './path-utils.js';
import type { Root } from '@modelcontextprotocol/sdk/types.js';
import { fileURLToPath } from "url";

/**
 * Converts a root URI to a normalized directory path with basic security validation.
 * @param rootUri - File URI (file://...) or plain directory path
 * @returns Promise resolving to validated path or null if invalid
 */
async function parseRootUri(rootUri: string): Promise<string | null> {
  try {
    const rawPath = rootUri.startsWith('file://') ? fileURLToPath(rootUri) : rootUri;
    const expandedPath = rawPath.startsWith('~/') || rawPath === '~' 
      ? path.join(os.homedir(), rawPath.slice(1)) 
      : rawPath;
    const absolutePath =

... (truncated -- full source via MCP)