How can PHP developers ensure that specific file types are allowed for upload while avoiding exclusion due to MIME type detection problems?

To ensure that specific file types are allowed for upload while avoiding exclusion due to MIME type detection problems, PHP developers can validate file types based on their file extensions rather than relying solely on MIME type detection. This approach helps prevent issues where the MIME type reported by the browser may not match the actual file content, leading to false rejections or acceptance of files. 

// Define an array of allowed file extensions
$allowedExtensions = array('jpg', 'jpeg', 'png', 'gif');

// Get the uploaded file's extension
$uploadedFileExtension = pathinfo($_FILES['file']['name'], PATHINFO_EXTENSION);

// Check if the uploaded file's extension is in the list of allowed extensions
if (in_array($uploadedFileExtension, $allowedExtensions)) {
    // File type is allowed, proceed with file upload
    move_uploaded_file($_FILES['file']['tmp_name'], 'uploads/' . $_FILES['file']['name']);
    echo 'File uploaded successfully.';
} else {
    // File type is not allowed
    echo 'Invalid file type. Only JPG, JPEG, PNG, and GIF files are allowed.';
}

Keywords

PHP file upload MIME type detection allowed file types validation

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