Merge pull request #2851 from olaservo/fix-wsl-path-conversion

Resolve filesystem issue where WSL paths are incorrectly converted to Windows format

src/filesystem/__tests__/path-utils.test.ts

@@ -10,14 +10,25 @@ describe('Path Utilities', () => {
         .toBe('/home/user/some path');
     });
 
-    it('converts WSL paths to Windows format', () => {
+    it('never converts WSL paths (they work correctly in WSL with Node.js fs)', () => {
+      // WSL paths should NEVER be converted, regardless of platform
+      // They are valid Linux paths that work with Node.js fs operations inside WSL
       expect(convertToWindowsPath('/mnt/c/NS/MyKindleContent'))
-        .toBe('C:\\NS\\MyKindleContent');
+        .toBe('/mnt/c/NS/MyKindleContent');
+      expect(convertToWindowsPath('/mnt/d/Documents'))
+        .toBe('/mnt/d/Documents');
     });
 
-    it('converts Unix-style Windows paths to Windows format', () => {
-      expect(convertToWindowsPath('/c/NS/MyKindleContent'))
-        .toBe('C:\\NS\\MyKindleContent');
+    it('converts Unix-style Windows paths only on Windows platform', () => {
+      // On Windows, /c/ style paths should be converted
+      if (process.platform === 'win32') {
+        expect(convertToWindowsPath('/c/NS/MyKindleContent'))
+          .toBe('C:\\NS\\MyKindleContent');
+      } else {
+        // On Linux, leave them unchanged
+        expect(convertToWindowsPath('/c/NS/MyKindleContent'))
+          .toBe('/c/NS/MyKindleContent');
+      }
     });
 
     it('leaves Windows paths unchanged but ensures backslashes', () => {
@@ -34,11 +45,20 @@ describe('Path Utilities', () => {
         .toBe('C:\\Program Files\\Some App');
     });
 
-    it('handles uppercase and lowercase drive letters', () => {
+    it('handles drive letter paths based on platform', () => {
+      // WSL paths should never be converted
       expect(convertToWindowsPath('/mnt/d/some/path'))
-        .toBe('D:\\some\\path');
-      expect(convertToWindowsPath('/d/some/path'))
-        .toBe('D:\\some\\path');
+        .toBe('/mnt/d/some/path');
+
+      if (process.platform === 'win32') {
+        // On Windows, Unix-style paths like /d/ should be converted
+        expect(convertToWindowsPath('/d/some/path'))
+          .toBe('D:\\some\\path');
+      } else {
+        // On Linux, /d/ is just a regular Unix path
+        expect(convertToWindowsPath('/d/some/path'))
+          .toBe('/d/some/path');
+      }
     });
   });
 
@@ -67,21 +87,33 @@ describe('Path Utilities', () => {
         .toBe('C:\\NS\\MyKindleContent');
     });
 
-    it('handles WSL paths', () => {
+    it('always preserves WSL paths (they work correctly in WSL)', () => {
+      // WSL paths should ALWAYS be preserved, regardless of platform
+      // This is the fix for issue #2795
       expect(normalizePath('/mnt/c/NS/MyKindleContent'))
-        .toBe('C:\\NS\\MyKindleContent');
+        .toBe('/mnt/c/NS/MyKindleContent');
+      expect(normalizePath('/mnt/d/Documents'))
+        .toBe('/mnt/d/Documents');
     });
 
     it('handles Unix-style Windows paths', () => {
-      expect(normalizePath('/c/NS/MyKindleContent'))
-        .toBe('C:\\NS\\MyKindleContent');
+      // On Windows, /c/ paths should be converted
+      if (process.platform === 'win32') {
+        expect(normalizePath('/c/NS/MyKindleContent'))
+          .toBe('C:\\NS\\MyKindleContent');
+      } else if (process.platform === 'linux') {
+        // On Linux, /c/ is just a regular Unix path
+        expect(normalizePath('/c/NS/MyKindleContent'))
+          .toBe('/c/NS/MyKindleContent');
+      }
     });
 
     it('handles paths with spaces and mixed slashes', () => {
       expect(normalizePath('C:/NS/My Kindle Content'))
         .toBe('C:\\NS\\My Kindle Content');
+      // WSL paths should always be preserved
       expect(normalizePath('/mnt/c/NS/My Kindle Content'))
-        .toBe('C:\\NS\\My Kindle Content');
+        .toBe('/mnt/c/NS/My Kindle Content');
       expect(normalizePath('C:\\Program Files (x86)\\App Name'))
         .toBe('C:\\Program Files (x86)\\App Name');
       expect(normalizePath('"C:\\Program Files\\App Name"'))
@@ -91,10 +123,19 @@ describe('Path Utilities', () => {
     });
 
     it('preserves spaces in all path formats', () => {
+      // WSL paths should always be preserved
       expect(normalizePath('/mnt/c/Program Files/App Name'))
-        .toBe('C:\\Program Files\\App Name');
-      expect(normalizePath('/c/Program Files/App Name'))
-        .toBe('C:\\Program Files\\App Name');
+        .toBe('/mnt/c/Program Files/App Name');
+
+      if (process.platform === 'win32') {
+        // On Windows, Unix-style paths like /c/ should be converted
+        expect(normalizePath('/c/Program Files/App Name'))
+          .toBe('C:\\Program Files\\App Name');
+      } else {
+        // On Linux, /c/ is just a regular Unix path
+        expect(normalizePath('/c/Program Files/App Name'))
+          .toBe('/c/Program Files/App Name');
+      }
       expect(normalizePath('C:/Program Files/App Name'))
         .toBe('C:\\Program Files\\App Name');
     });
@@ -105,15 +146,16 @@ describe('Path Utilities', () => {
         .toBe('C:\\NS\\Sub&Folder');
       expect(normalizePath('C:/NS/Sub&Folder'))
         .toBe('C:\\NS\\Sub&Folder');
+      // WSL paths should always be preserved
       expect(normalizePath('/mnt/c/NS/Sub&Folder'))
-        .toBe('C:\\NS\\Sub&Folder');
-      
+        .toBe('/mnt/c/NS/Sub&Folder');
+
       // Test tilde in path (short names in Windows)
       expect(normalizePath('C:\\NS\\MYKIND~1'))
         .toBe('C:\\NS\\MYKIND~1');
       expect(normalizePath('/Users/NEMANS~1/FOLDER~2/SUBFO~1/Public/P12PST~1'))
         .toBe('/Users/NEMANS~1/FOLDER~2/SUBFO~1/Public/P12PST~1');
-      
+
       // Test other special characters
       expect(normalizePath('C:\\Path with #hash'))
         .toBe('C:\\Path with #hash');
@@ -128,10 +170,19 @@ describe('Path Utilities', () => {
     it('capitalizes lowercase drive letters for Windows paths', () => {
       expect(normalizePath('c:/windows/system32'))
         .toBe('C:\\windows\\system32');
-      expect(normalizePath('/mnt/d/my/folder')) // WSL path with lowercase drive
-        .toBe('D:\\my\\folder');
-      expect(normalizePath('/e/another/folder')) // Unix-style Windows path with lowercase drive
-        .toBe('E:\\another\\folder');
+      // WSL paths should always be preserved
+      expect(normalizePath('/mnt/d/my/folder'))
+        .toBe('/mnt/d/my/folder');
+
+      if (process.platform === 'win32') {
+        // On Windows, Unix-style paths should be converted and capitalized
+        expect(normalizePath('/e/another/folder'))
+          .toBe('E:\\another\\folder');
+      } else {
+        // On Linux, /e/ is just a regular Unix path
+        expect(normalizePath('/e/another/folder'))
+          .toBe('/e/another/folder');
+      }
     });
 
     it('handles UNC paths correctly', () => {
@@ -172,4 +223,132 @@ describe('Path Utilities', () => {
       expect(expandHome('C:/test')).toBe('C:/test');
     });
   });
+
+  describe('WSL path handling (issue #2795 fix)', () => {
+    // Save original platform
+    const originalPlatform = process.platform;
+
+    afterEach(() => {
+      // Restore platform after each test
+      Object.defineProperty(process, 'platform', {
+        value: originalPlatform,
+        writable: true,
+        configurable: true
+      });
+    });
+
+    it('should NEVER convert WSL paths - they work correctly in WSL with Node.js fs', () => {
+      // The key insight: When running `wsl npx ...`, Node.js runs INSIDE WSL (process.platform === 'linux')
+      // and /mnt/c/ paths work correctly with Node.js fs operations in that environment.
+      // Converting them to C:\ format breaks fs operations because Windows paths don't work inside WSL.
+
+      // Mock Linux platform (inside WSL)
+      Object.defineProperty(process, 'platform', {
+        value: 'linux',
+        writable: true,
+        configurable: true
+      });
+
+      // WSL paths should NOT be converted, even inside WSL
+      expect(normalizePath('/mnt/c/Users/username/folder'))
+        .toBe('/mnt/c/Users/username/folder');
+
+      expect(normalizePath('/mnt/d/Documents/project'))
+        .toBe('/mnt/d/Documents/project');
+    });
+
+    it('should also preserve WSL paths when running on Windows', () => {
+      // Mock Windows platform
+      Object.defineProperty(process, 'platform', {
+        value: 'win32',
+        writable: true,
+        configurable: true
+      });
+
+      // WSL paths should still be preserved (though they wouldn't be accessible from Windows Node.js)
+      expect(normalizePath('/mnt/c/Users/username/folder'))
+        .toBe('/mnt/c/Users/username/folder');
+
+      expect(normalizePath('/mnt/d/Documents/project'))
+        .toBe('/mnt/d/Documents/project');
+    });
+
+    it('should convert Unix-style Windows paths (/c/) only when running on Windows (win32)', () => {
+      // Mock process.platform to be 'win32' (Windows)
+      Object.defineProperty(process, 'platform', {
+        value: 'win32',
+        writable: true,
+        configurable: true
+      });
+
+      // Unix-style Windows paths like /c/ should be converted on Windows
+      expect(normalizePath('/c/Users/username/folder'))
+        .toBe('C:\\Users\\username\\folder');
+
+      expect(normalizePath('/d/Documents/project'))
+        .toBe('D:\\Documents\\project');
+    });
+
+    it('should NOT convert Unix-style paths (/c/) when running inside WSL (linux)', () => {
+      // Mock process.platform to be 'linux' (WSL/Linux)
+      Object.defineProperty(process, 'platform', {
+        value: 'linux',
+        writable: true,
+        configurable: true
+      });
+
+      // When on Linux, /c/ is just a regular Unix directory, not a drive letter
+      expect(normalizePath('/c/some/path'))
+        .toBe('/c/some/path');
+
+      expect(normalizePath('/d/another/path'))
+        .toBe('/d/another/path');
+    });
+
+    it('should preserve regular Unix paths on all platforms', () => {
+      // Test on Linux
+      Object.defineProperty(process, 'platform', {
+        value: 'linux',
+        writable: true,
+        configurable: true
+      });
+
+      expect(normalizePath('/home/user/documents'))
+        .toBe('/home/user/documents');
+
+      expect(normalizePath('/var/log/app'))
+        .toBe('/var/log/app');
+
+      // Test on Windows (though these paths wouldn't work on Windows)
+      Object.defineProperty(process, 'platform', {
+        value: 'win32',
+        writable: true,
+        configurable: true
+      });
+
+      expect(normalizePath('/home/user/documents'))
+        .toBe('/home/user/documents');
+
+      expect(normalizePath('/var/log/app'))
+        .toBe('/var/log/app');
+    });
+
+    it('reproduces exact scenario from issue #2795', () => {
+      // Simulate running inside WSL: wsl npx @modelcontextprotocol/server-filesystem /mnt/c/Users/username/folder
+      Object.defineProperty(process, 'platform', {
+        value: 'linux',
+        writable: true,
+        configurable: true
+      });
+
+      // This is the exact path from the issue
+      const inputPath = '/mnt/c/Users/username/folder';
+      const result = normalizePath(inputPath);
+
+      // Should NOT convert to C:\Users\username\folder
+      expect(result).toBe('/mnt/c/Users/username/folder');
+      expect(result).not.toContain('C:');
+      expect(result).not.toContain('\\');
+    });
+  });
 });