What are some common pitfalls to avoid when programming file upload functionality in PHP?

One common pitfall to avoid when programming file upload functionality in PHP is not validating the file type and size before allowing it to be uploaded. This can lead to security vulnerabilities such as allowing malicious files to be uploaded to the server. To prevent this, always validate the file type and size before processing the upload. 

// Validate file type and size before uploading
$allowedTypes = ['image/jpeg', 'image/png'];
$maxSize = 1048576; // 1MB

if (!in_array($_FILES['file']['type'], $allowedTypes)) {
    die('Invalid file type. Allowed types are JPEG and PNG.');
}

if ($_FILES['file']['size'] > $maxSize) {
    die('File is too large. Maximum size allowed is 1MB.');
}

// Proceed with file upload
// Your file upload code here

Keywords

file upload PHP security vulnerabilities file size limit error handling

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