From 7ae389b50659bec9573e4f60633265fd6b3cb610 Mon Sep 17 00:00:00 2001
From: tarunag10 <tarunag10@hotmail.com>
Date: Tue, 2 Jun 2026 11:24:21 +0100
Subject: [PATCH] Improve filesystem startup directory diagnostics

---
 .../__tests__/startup-validation.test.ts      | 14 ++++++++--
 src/filesystem/index.ts                       | 26 +++++++++++++++++--
 2 files changed, 36 insertions(+), 4 deletions(-)

diff --git a/src/filesystem/__tests__/startup-validation.test.ts b/src/filesystem/__tests__/startup-validation.test.ts
index 3be283df74..fa697c2e42 100644
--- a/src/filesystem/__tests__/startup-validation.test.ts
+++ b/src/filesystem/__tests__/startup-validation.test.ts
@@ -18,6 +18,9 @@ async function spawnServer(args: string[], timeoutMs = 2000): Promise<{ exitCode
     let stderr = '';
     proc.stderr?.on('data', (data) => {
       stderr += data.toString();
+      if (stderr.includes('Secure MCP Filesystem Server running on stdio')) {
+        proc.kill('SIGTERM');
+      }
     });
 
     const timeout = setTimeout(() => {
@@ -66,8 +69,10 @@ describe('Startup Directory Validation', () => {
     const result = await spawnServer([nonExistentDir, accessibleDir]);
 
     // Should warn about inaccessible directory
-    expect(result.stderr).toContain('Warning: Cannot access directory');
+    expect(result.stderr).toContain('Warning: Skipping invalid allowed directory');
     expect(result.stderr).toContain(nonExistentDir);
+    expect(result.stderr).toContain('ENOENT');
+    expect(result.stderr).toContain('no such file or directory');
 
     // Should still start successfully
     expect(result.stderr).toContain('Secure MCP Filesystem Server running on stdio');
@@ -82,6 +87,10 @@ describe('Startup Directory Validation', () => {
     // Should exit with error
     expect(result.exitCode).toBe(1);
     expect(result.stderr).toContain('Error: None of the specified directories are accessible');
+    expect(result.stderr).toContain('Invalid allowed directories:');
+    expect(result.stderr).toContain(nonExistent1);
+    expect(result.stderr).toContain(nonExistent2);
+    expect(result.stderr).toContain('ENOENT');
   });
 
   it('should warn when path is not a directory', async () => {
@@ -91,7 +100,8 @@ describe('Startup Directory Validation', () => {
     const result = await spawnServer([filePath, accessibleDir]);
 
     // Should warn about non-directory
-    expect(result.stderr).toContain('Warning:');
+    expect(result.stderr).toContain('Warning: Skipping invalid allowed directory');
+    expect(result.stderr).toContain(filePath);
     expect(result.stderr).toContain('not a directory');
 
     // Should still start with the valid directory
diff --git a/src/filesystem/index.ts b/src/filesystem/index.ts
index 7b67e63e58..05bd21c08f 100644
--- a/src/filesystem/index.ts
+++ b/src/filesystem/index.ts
@@ -28,6 +28,19 @@ import {
   setAllowedDirectories,
 } from './lib.js';
 
+type InvalidAllowedDirectory = {
+  directory: string;
+  reason: string;
+};
+
+function formatStartupValidationError(error: unknown): string {
+  if (error instanceof Error) {
+    return error.message;
+  }
+
+  return String(error);
+}
+
 // Command line argument parsing
 const args = process.argv.slice(2);
 if (args.length === 0) {
@@ -68,22 +81,31 @@ let allowedDirectories = (await Promise.all(
 
 // Filter to only accessible directories, warn about inaccessible ones
 const accessibleDirectories: string[] = [];
+const invalidDirectories: InvalidAllowedDirectory[] = [];
 for (const dir of allowedDirectories) {
   try {
     const stats = await fs.stat(dir);
     if (stats.isDirectory()) {
       accessibleDirectories.push(dir);
     } else {
-      console.error(`Warning: ${dir} is not a directory, skipping`);
+      const reason = "not a directory";
+      invalidDirectories.push({ directory: dir, reason });
+      console.error(`Warning: Skipping invalid allowed directory "${dir}": ${reason}`);
     }
   } catch (error) {
-    console.error(`Warning: Cannot access directory ${dir}, skipping`);
+    const reason = `cannot access: ${formatStartupValidationError(error)}`;
+    invalidDirectories.push({ directory: dir, reason });
+    console.error(`Warning: Skipping invalid allowed directory "${dir}": ${reason}`);
   }
 }
 
 // Exit only if ALL paths are inaccessible (and some were specified)
 if (accessibleDirectories.length === 0 && allowedDirectories.length > 0) {
   console.error("Error: None of the specified directories are accessible");
+  console.error("Invalid allowed directories:");
+  for (const { directory, reason } of invalidDirectories) {
+    console.error(`  - ${directory}: ${reason}`);
+  }
   process.exit(1);
 }