Added filesystem module

mcpServer/modules/filesystem/roots-utils.ts

@@ -0,0 +1,76 @@
+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';
+
+/**
+ * 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://') ? rootUri.slice(7) : rootUri;
+    const expandedPath = rawPath.startsWith('~/') || rawPath === '~' 
+      ? path.join(os.homedir(), rawPath.slice(1)) 
+      : rawPath;
+    const absolutePath = path.resolve(expandedPath);
+    const resolvedPath = await fs.realpath(absolutePath);
+    return normalizePath(resolvedPath);
+  } catch {
+    return null; // Path doesn't exist or other error
+  }
+}
+
+/**
+ * Formats error message for directory validation failures.
+ * @param dir - Directory path that failed validation
+ * @param error - Error that occurred during validation
+ * @param reason - Specific reason for failure
+ * @returns Formatted error message
+ */
+function formatDirectoryError(dir: string, error?: unknown, reason?: string): string {
+  if (reason) {
+    return `Skipping ${reason}: ${dir}`;
+  }
+  const message = error instanceof Error ? error.message : String(error);
+  return `Skipping invalid directory: ${dir} due to error: ${message}`;
+}
+
+/**
+ * Resolves requested root directories from MCP root specifications.
+ * 
+ * Converts root URI specifications (file:// URIs or plain paths) into normalized
+ * directory paths, validating that each path exists and is a directory.
+ * Includes symlink resolution for security.
+ * 
+ * @param requestedRoots - Array of root specifications with URI and optional name
+ * @returns Promise resolving to array of validated directory paths
+ */
+export async function getValidRootDirectories(
+  requestedRoots: readonly Root[]
+): Promise<string[]> {
+  const validatedDirectories: string[] = [];
+  
+  for (const requestedRoot of requestedRoots) {
+    const resolvedPath = await parseRootUri(requestedRoot.uri);
+    if (!resolvedPath) {
+      console.error(formatDirectoryError(requestedRoot.uri, undefined, 'invalid path or inaccessible'));
+      continue;
+    }
+    
+    try {
+      const stats: Stats = await fs.stat(resolvedPath);
+      if (stats.isDirectory()) {
+        validatedDirectories.push(resolvedPath);
+      } else {
+        console.error(formatDirectoryError(resolvedPath, undefined, 'non-directory root'));
+      }
+    } catch (error) {
+      console.error(formatDirectoryError(resolvedPath, error));
+    }
+  }
+  
+  return validatedDirectories;
+}