GReader.php

<?php

class GReader {

	protected $auth;

	public function __construct($login, $password) {
		$clientlogin_url = "https://www.google.com/accounts/ClientLogin";
		$clientlogin_post = array(
		    "accountType" => "HOSTED_OR_GOOGLE",
		    "Email" => $login,
		    "Passwd" => $password,
		    "service" => "writely",
		    "source" => "my-fake-app"
		);

		// Initialize the curl object
		$curl = curl_init($clientlogin_url);

		// Set some options (some for SHTTP)
		curl_setopt($curl, CURLOPT_POST, true);
		curl_setopt($curl, CURLOPT_POSTFIELDS, $clientlogin_post);
		curl_setopt($curl, CURLOPT_HTTPAUTH, CURLAUTH_ANY);
		curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
		curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);

		// Execute
		$response = curl_exec($curl);

		// Get the Auth string and save it
		preg_match("/Auth=([a-z0-9_-]+)/i", $response, $matches);
		$this->auth = $matches[1];

		curl_close($curl);
	}

	protected function createParser($options) {
		$sax = xml_parser_create();
		xml_parser_set_option($sax, XML_OPTION_CASE_FOLDING, false);
		xml_parser_set_option($sax, XML_OPTION_SKIP_WHITE, true);
		xml_set_element_handler($sax, $options['onStart'], $options['onEnd']);
		return $sax;
	}
	public function request($url, $method, $params=array()) {
		$curl = curl_init($url);

		$parserOptions = array(
			'onStart'=>function () {
				var_dump('START:');
				var_dump(func_get_args());
			},
			'onEnd'=>function () {
				var_dump('END:');
				var_dump(func_get_args());
			}
		);

		$ctx = stream_context_create(array(
			'gxml'=>array(
				'parser'=>$this->createParser($parserOptions)
		)));

		$fp = fopen("gxml://nothing", "r+", false, $ctx);

		curl_setopt($curl, CURLOPT_HTTPAUTH, CURLAUTH_ANY);
		curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
		// curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
		curl_setopt($curl, CURLOPT_FILE, $fp);
		curl_setopt($curl, CURLOPT_POST, $method==='post');

		$headers = array(
		    "Authorization: GoogleLogin auth=" . $this->auth,
		    "GData-Version: 3.0",
		);

		curl_setopt($curl, CURLOPT_HTTPHEADER, $headers);

		$response = curl_exec($curl);
		curl_close($curl);

		fclose($fp);


		return $response;
	}

}


class GXMLStream {
    protected $buffer;
    public $context;

    function stream_open($path, $mode, $options, &$opened_path) {
        // Has to be declared, it seems...
        var_dump('Opening');
        $ctx = $this->context;
        $options = stream_context_get_options($ctx);

        var_dump($options);
        $this->parser = $options['gxml']['parser'];
        return true;
    }

    public function stream_write($data) {
        // var_dump('data:');
        // var_dump($data);

        xml_parse($this->parser, $data);
        return strlen($data);
    }
}

stream_wrapper_register("gxml", "GXMLStream")
    or die("Failed to register protocol");

USAGE.php

<?php
require_once('GReader.php');

$gr = new GReader('my@user.name', 'P455\/\/0rD');
$gr->request('https://docs.google.com/feeds/default/private/full', 'get');