You have been assigned a task to implement a logging system for a large software project. The logging system should log various events and actions that occur within the software. However, you notice that there is a potential issue with the current implementation.

The code snippet provided uses a logging function to write log messages to a file. However, it is missing the necessary checks and error handling to ensure that the file is opened and closed properly.

Your task is to modify the code snippet to add the necessary checks and error handling. Specifically, you need to:

1. Add code to check if the file exists before attempting to open it for writing. If the file does not exist, display an error message: "File not found." Additionally, if the file exists, but the current user does not have the necessary permissions to write to the file, display an error message: "Insufficient permissions to write to the file."

2. Add code to handle the case where the file fails to open properly. In addition to displaying an error message: "Failed to open the file," prompt the user to enter a new file name or provide an option to create a new file.

3. Add code to ensure that the file is closed properly after writing the log message. If the file fails to close, display an error message: "Failed to close the file." Additionally, implement a mechanism to automatically reopen the file and continue logging if the file is closed unexpectedly.

Modify the code snippet to fix these issues and make the logging system more robust.
user
Sure, I'd be happy to help modify the provided code snippet to handle the issues you've highlighted. Here's how you might adapt the code:

Assuming you're using Python, since that's a commonly used language for logging, this is a basic example using the built-in `logging` module. The `with open()` block ensures that the file is closed properly regardless of whether an exception is raised during file reading, writing, or closing. The `raise` keyword can be used to re-raise the exception that caused it.

```python
import logging
import os

def write_to_log(log_message, filename):
    """Writes log message to file."""
    if not os.path.exists(filename):
        logging.error('File not found.')
        raise FileNotFoundError(filename)
    elif not os.access(filename, os.W_OK):
        logging.error('Insufficient permissions to write to the file.')
        raise PermissionError(filename)
    else:
        with open(filename, 'a') as log_file:
            log_file.write(f'{log_message}\n')

# Example usage:
write_to_log('This is a log message.', 'example.log')
```

This function handles the case of a missing file or insufficient permissions to write to the file. If either of these errors occurs, it logs a helpful error message, raises a specific exception related to the error, and returns immediately to prevent further logging.

However, for the third issue, you could expand on this function by adding a check to ensure that the `close()` method works on the file before attempting to write to it. This is because a method like `close()` may return `None`, and a `raise` with a `NotImplementedError` would be more appropriate, provided that the rest of your program assumes this method should never return `None`.

```python
import logging
import os

def write_to_log(log_message, filename):
    """Writes log message to file."""
    if not os.path.exists(filename):
        logging.error('File not found.')
        raise FileNotFoundError(filename)
    elif not os.access(filename, os.W_OK):
        logging.error('Insufficient permissions to write to the file.')
        raise PermissionError(filename)
    else:
        with open(filename, 'a') as log_file:
            # Check if close method works
            if not hasattr(log_file, 'close'):
                raise NotImplementedError('close method not implemented for files opened using os.open')
            # Check if close method returns None
            elif log_file.close() is None:
                raise NotImplementedError('close method for file returns None.')
            else:
                log_file.write(f'{log_message}\n')
```

This function would display a logging message but only raises a `NotImplementedError` as log files can not have a `close()` call. You could also create a mechanism to re-open the log file in case `close()` is called unexpectedly, then continue logging instead of failing the script.
assistant
You have been assigned a task to implement a logging system for a large software project. The logging system should log various events and actions that occur within the software. However, you notice that there is a potential issue with the current implementation.

The code snippet provided uses a logging function to write log messages to a file. However, it is missing the necessary checks and error handling to ensure that the file is opened and closed properly.

Your task is to modify the code snippet to add the necessary checks and error handling. Specifically, you need to:

1. Add code to check if the file exists before attempting to open it for writing. If the file does not exist, display an error message: "File not found." Additionally, if the file exists, but the current user does not have the necessary permissions to write to the file, display an error message: "Insufficient permissions to write to the file."

2. Add code to handle the case where the file fails to open properly. In addition to displaying an error message: "Failed to open the file," prompt the user to enter a new file name or provide an option to create a new file.

3. Add code to ensure that the file is closed properly after writing the log message. If the file fails to close, display an error message: "Failed to close the file." Additionally, implement a mechanism to automatically reopen the file and continue logging if the file is closed unexpectedly.

Modify the code snippet to fix these issues and make the logging system more robust.
user
Here is the modified code snippet that addresses the issues mentioned:

```python
import os
import logging
from logging.handlers import RotatingFileHandler

def setup_logger(logger_name, log_file, level=logging.INFO):
    l = logging.getLogger(logger_name)
    formatter = logging.Formatter('%(asctime)s : %(module)s : %(lineno)d : %(funcName)s : %(message)s')
    file_handler = RotatingFileHandler(log_file, mode='a', maxBytes=5*1024*1024, backupCount=2)
    file_handler.setFormatter(formatter)

    if not os.path.exists(log_file):
        print("File not found.")
        create_file = input("Do you want to create a new file? y/n ")
        if create_file == 'y':
            open(log_file, 'a').close()
        else:
            return None

    try:
        file_handler.open()
    except PermissionError:
        print("Insufficient permissions to write to the file.")
        return None
    except Exception as e:
        print("Failed to open the file.", str(e))
        new_file_name = input("Enter a new file name or 'r' to retry with the same file: ")
        if new_file_name != 'r':
            return setup_logger(logger_name, new_file_name)
        else:
            return None

    l.setLevel(level)
    l.addHandler(file_handler)

    return l

logger = setup_logger('log_test', 'test.log')
logger.error('Test error message')

try:
    logger.handlers[0].close()
except Exception as e:
    print("Failed to close the file.", str(e))

# Automatically reopen the file and continue logging if the file is closed unexpectedly
if not logger.handlers[0].stream:
    logger.handlers[0].open()

logger.error('Test error message after file close')
```

This modified code uses the `os` module to check if the file exists and the `RotatingFileHandler` of the `logging` module to handle the opening, closing, and rotation of log files. If the file doesn't exist, it prompts the user to create a new file or exit. If the file opening fails due to Permission Error, it informs the user about it and exits. If the file opening fails for any other reason, it gives the user the option to enter a new file name or retry with the same file. If the file closing fails, it informs the user about it. After closing the file, it checks if the file handler's stream attribute is False (meaning the file is closed) and opens the file again to continue logging.
assistant