What are the best practices for handling user input in PHP to prevent security risks like file manipulation?

When handling user input in PHP, it is important to sanitize and validate the input to prevent security risks like file manipulation. One way to do this is by using functions like `filter_input()` or `htmlspecialchars()` to sanitize the input and validate it against expected formats. Additionally, it is crucial to never trust user input and always validate and sanitize it before using it in any file operations. 

// Sanitize and validate user input to prevent security risks like file manipulation
$user_input = filter_input(INPUT_POST, 'user_input', FILTER_SANITIZE_STRING);

// Validate the input against expected formats
if (preg_match("/^[a-zA-Z0-9]+$/", $user_input)) {
    // Proceed with file operations using the sanitized user input
    $file_path = '/path/to/files/' . $user_input;
    // Perform file operations like reading, writing, or deleting
} else {
    // Handle invalid input error
    echo "Invalid input. Please provide a valid input.";
}

Keywords

input validation data sanitization file upload security cross-site scripting (XSS) SQL injection

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