Physical path to website relative path ASP.NET

FileInfoExtensions.cs

public static partial class FileInfoExtensions
{
	public static string ToWebSiteRelativePath(this FileInfo fileInfo)
	{
		var applicationPhysicalPath = HostingEnvironment.ApplicationPhysicalPath;
		var filePhysicalPath = fileInfo.FullName;
		if (filePhysicalPath.StartsWith(applicationPhysicalPath) == false)
			throw new ArgumentOutOfRangeException(filePhysicalPath + " is not within application physical path: " + applicationPhysicalPath);
		return filePhysicalPath.Replace(applicationPhysicalPath, HostingEnvironment.ApplicationVirtualPath + "/").Replace("\\", "/");
	}
}