What are some best practices for allowing users to upload images to a server in PHP?

When allowing users to upload images to a server in PHP, it is important to validate the file type, size, and ensure secure file handling to prevent any potential security risks. One common best practice is to use PHP's built-in functions like `move_uploaded_file()` to securely move the uploaded file to a designated directory on the server. 

<?php
// Check if the file was uploaded without errors
if (isset($_FILES['image']) && $_FILES['image']['error'] == UPLOAD_ERR_OK) {
    $targetDir = 'uploads/';
    $targetFile = $targetDir . basename($_FILES['image']['name']);
    
    // Validate file type
    $imageFileType = strtolower(pathinfo($targetFile, PATHINFO_EXTENSION));
    if ($imageFileType != 'jpg' && $imageFileType != 'png' && $imageFileType != 'jpeg' && $imageFileType != 'gif') {
        echo 'Invalid file format. Please upload a JPG, JPEG, PNG, or GIF file.';
        exit;
    }
    
    // Validate file size
    if ($_FILES['image']['size'] > 5000000) {
        echo 'File is too large. Please upload a file smaller than 5MB.';
        exit;
    }
    
    // Move the uploaded file to the target directory
    if (move_uploaded_file($_FILES['image']['tmp_name'], $targetFile)) {
        echo 'File uploaded successfully.';
    } else {
        echo 'Error uploading file.';
    }
} else {
    echo 'Error uploading file.';
}
?>

Keywords

file upload move_uploaded_file image processing file permissions error handling

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