feat(shell_executor.py): add directory validation before command execution to handle directory permission issues

test(shell_executor.py): add unit test for command execution with restricted directory permissions to ensure proper error handling

Author: tumf

src/mcp_shell_server/shell_executor.py

@@ -378,6 +378,18 @@ async def execute(
         start_time = time.time()
 
         try:
+            # Validate directory if specified
+            try:
+                self._validate_directory(directory)
+            except ValueError as e:
+                return {
+                    "error": str(e),
+                    "status": 1,
+                    "stdout": "",
+                    "stderr": str(e),
+                    "execution_time": time.time() - start_time,
+                }
+
             # Preprocess command to handle pipe operators
             preprocessed_command = self._preprocess_command(command)
             cleaned_command = self._clean_command(preprocessed_command)

tests/test_shell_executor.py

@@ -388,3 +388,22 @@ async def test_complex_pipeline_with_redirections(executor, temp_test_dir, monke
         assert len(lines) == 2
         assert lines[0].strip() == "HELLO"
         assert lines[1].strip() == "WORLD"
+
+
+@pytest.mark.asyncio
+async def test_directory_permissions(executor, temp_test_dir, monkeypatch):
+    """Test command execution with directory permission issues"""
+    monkeypatch.setenv("ALLOW_COMMANDS", "ls")
+
+    # Create a directory with no execute permission
+    no_exec_dir = os.path.join(temp_test_dir, "no_exec_dir")
+    os.mkdir(no_exec_dir)
+    os.chmod(no_exec_dir, 0o600)  # Remove execute permission
+
+    try:
+        result = await executor.execute(["ls"], directory=no_exec_dir)
+        assert result["error"] == f"Directory is not accessible: {no_exec_dir}"
+        assert result["status"] == 1
+    finally:
+        # Restore permissions for cleanup
+        os.chmod(no_exec_dir, 0o700)