src/PEAR/Registry.php
function _channelExists($channel, $noaliases = false)
    {
        $a = file_exists($this->_channelFileName($channel, $noaliases));
        if (!$a && $channel == 'pear.php.net') {
            return true;
        }

        if (!$a && $channel == 'pecl.php.net') {
            return true;
        }

        if (!$a && $channel == 'doc.php.net') {
            return true;
        }

        return $a;
    }
function _channelExists($channel, $noaliases = false)
    {
        $a = file_exists($this->_channelFileName($channel, $noaliases));
        if (!$a && $channel == 'pear.php.net') {
            return true;
        }

        if (!$a && $channel == 'pecl.php.net') {
            return true;
        }

        if (!$a && $channel == 'doc.php.net') {
            return true;
        }

        return $a;
    }
Determine whether a channel exists in the registry

@param string Channel name
@param bool if true, then aliases will be ignored
@return boolean