Patched code sample

import os
import re
from pathlib import Path
from typing import Any, Dict, Optional

class SecureDataProcessor:
    """Secure data processor with comprehensive validation"""
    
    def __init__(self, max_input_size: int = 10000, max_output_size: int = 50000):
        self.max_input_size = max_input_size
        self.max_output_size = max_output_size
        self.allowed_file_dir = Path('./safe_files').resolve()
    
    def process_user_data_secure(self, user_input: Any) -> Optional[Dict[str, Any]]:
        """Securely process user data with comprehensive validation"""
        try:
            # Input validation
            if user_input is None:
                return {"error": "Input is required"}
            
            # Type validation
            if not isinstance(user_input, (str, int, float)):
                return {"error": "Invalid input type"}
            
            # Size validation
            input_str = str(user_input)
            if len(input_str) > self.max_input_size:
                return {"error": "Input too large"}
            
            # Content sanitization
            sanitized_input = self._sanitize_input(input_str)
            
            # Safe processing with limits
            processed = self._process_safely(sanitized_input)
            
            # Output validation
            if not self._validate_output(processed):
                return {"error": "Output validation failed"}
            
            # Return secure result (no sensitive information)
            return {
                "result": processed,
                "status": "success",
                "length": len(processed) if processed else 0
            }
            
        except Exception:
            # Secure error handling - no information leakage
            return {"error": "Processing failed", "status": "error"}
    
    def safe_file_operation(self, filename: str) -> Optional[str]:
        """Safe file operation with path validation"""
        try:
            # Input validation
            if not filename or not isinstance(filename, str):
                return None
            
            # Sanitize filename
            if not self._is_safe_filename(filename):
                return None
            
            # Resolve file path safely
            file_path = (self.allowed_file_dir / filename).resolve()
            
            # Ensure file is within allowed directory
            if not str(file_path).startswith(str(self.allowed_file_dir)):
                return None
            
            # Check if file exists and is readable
            if not file_path.exists() or not file_path.is_file():
                return None
            
            # Read file with size limit
            try:
                with open(file_path, 'r', encoding='utf-8') as f:
                    content = f.read(self.max_input_size)  # Size limit
                
                return content
                
            except (IOError, UnicodeDecodeError):
                return None
                
        except Exception:
            return None
    
    def _sanitize_input(self, input_str: str) -> str:
        """Sanitize input string"""
        # Remove control characters
        sanitized = re.sub(r'[\x00-\x1f\x7f-\x9f]', '', input_str)
        
        # Remove potentially dangerous patterns
        sanitized = re.sub(r'[<>&"\']', '', sanitized)
        
        # Normalize whitespace
        sanitized = re.sub(r'\s+', ' ', sanitized).strip()
        
        return sanitized[:1000]  # Length limit
    
    def _process_safely(self, data: str) -> str:
        """Process data safely with bounds checking"""
        if not data:
            return ""
        
        # Safe processing - no multiplication that could cause DoS
        processed = data.upper()
        
        # Apply length limit
        if len(processed) > 5000:
            processed = processed[:5000]
        
        return processed
    
    def _validate_output(self, output: Any) -> bool:
        """Validate output for security"""
        if output is None:
            return True
        
        if isinstance(output, str):
            # Check output size
            if len(output) > self.max_output_size:
                return False
            
            # Check for suspicious content
            if any(char in output for char in '<>&"\''):
                return False
        
        return True
    
    def _is_safe_filename(self, filename: str) -> bool:
        """Validate filename for safety"""
        if not filename or len(filename) > 255:
            return False
        
        # Check for path traversal
        if '..' in filename or filename.startswith('/'):
            return False
        
        # Only allow safe characters
        if not re.match(r'^[a-zA-Z0-9._-]+$', filename):
            return False
        
        return True

# Secure usage:
processor = SecureDataProcessor()
result = processor.process_user_data_secure("safe input data")
file_content = processor.safe_file_operation("safe_file.txt")