file-server-rules

---

type: auto-attached name: "File Server Specific Rules" description: "Rules specific to file server development" glob: "servers/file-server/**/*"

File Server Specific Development Rules

Core File Operations

Async File Operations

import aiofiles
import aiofiles.os
from pathlib import Path

async def read_file_safely(file_path: str) -> bytes:
    """Always use async file operations"""
    try:
        async with aiofiles.open(file_path, 'rb') as f:
            return await f.read()
    except FileNotFoundError:
        raise ValueError(f"File not found: {file_path}")
    except PermissionError:
        raise ValueError(f"Permission denied: {file_path}")

File Path Security

from pathlib import Path
import os

def validate_file_path(file_path: str, base_dir: str) -> Path:
    """Prevent directory traversal attacks"""
    # Resolve path and ensure it's within base directory
    resolved_path = Path(base_dir).resolve() / Path(file_path).name
    
    if not str(resolved_path).startswith(str(Path(base_dir).resolve())):
        raise ValueError("Invalid file path: directory traversal detected")
    
    return resolved_path

File Operations Standards

File Type Validation

import mimetypes
from typing import List

ALLOWED_MIME_TYPES = [
    'text/plain',
    'text/csv',
    'application/json',
    'application/pdf',
    'image/png',
    'image/jpeg'
]

def validate_file_type(file_path: str, allowed_types: List[str] = ALLOWED_MIME_TYPES) -> bool:
    """Validate file type before processing"""
    mime_type, _ = mimetypes.guess_type(file_path)
    return mime_type in allowed_types

File Size Limits

import os
from typing import Optional

MAX_FILE_SIZE = 10 * 1024 * 1024  # 10MB

async def check_file_size(file_path: str, max_size: Optional[int] = None) -> None:
    """Check file size before processing"""
    max_size = max_size or MAX_FILE_SIZE
    file_size = await aiofiles.os.path.getsize(file_path)
    
    if file_size > max_size:
        raise ValueError(f"File too large: {file_size} bytes (max: {max_size})")