Finding what headers and content were already been sent

Hello, I need to find out, at any point in a PHP script, which headers and what content (HTML or other) have been sent already. I know I can use output buffering, but in my case, this is not going to work. By the way, I know that PHP's phpinfo() function lists headers received and headers sent, but I couldn't find how can I access them in PHP. In addition, how do I know what content has been sent at any point in a script? Thanks in advance for your help. Noor P.S.: Output buffer is not an option, so no solution there.