src/PEAR/Common.php
function downloadHttp($url, &$ui, $save_dir = '.', $callback = null)
    {
        if (!class_exists('PEAR_Downloader')) {
            require_once 'PEAR/Downloader.php';
        }
        return PEAR_Downloader::downloadHttp($url, $ui, $save_dir, $callback);
    }
function downloadHttp($url, &$ui, $save_dir = '.', $callback = null)
    {
        if (!class_exists('PEAR_Downloader')) {
            require_once 'PEAR/Downloader.php';
        }
        return PEAR_Downloader::downloadHttp($url, $ui, $save_dir, $callback);
    }
Download a file through HTTP.  Considers suggested file name in
Content-disposition: header and can run a callback function for
different events.  The callback will be called with two
parameters: the callback type, and parameters.  The implemented
callback types are:

'setup'       called at the very beginning, parameter is a UI object
that should be used for all output
'message'     the parameter is a string with an informational message
'saveas'      may be used to save with a different file name, the
parameter is the filename that is about to be used.
If a 'saveas' callback returns a non-empty string,
that file name will be used as the filename instead.
Note that $save_dir will not be affected by this, only
the basename of the file.
'start'       download is starting, parameter is number of bytes
that are expected, or -1 if unknown
'bytesread'   parameter is the number of bytes read so far
'done'        download is complete, parameter is the total number
of bytes read
'connfailed'  if the TCP connection fails, this callback is called
with array(host,port,errno,errmsg)
'writefailed' if writing to disk fails, this callback is called
with array(destfile,errmsg)

If an HTTP proxy has been configured (http_proxy PEAR_Config
setting), the proxy will be used.

@param string  $url       the URL to download
@param object  $ui        PEAR_Frontend_* instance
@param object  $config    PEAR_Config instance
@param string  $save_dir  (optional) directory to save file in
@param mixed   $callback  (optional) function/method to call for status
updates

@return string  Returns the full path of the downloaded file or a PEAR
error on failure.  If the error is caused by
socket-related errors, the error object will
have the fsockopen error code available through
getCode().

@access public
@deprecated in favor of PEAR_Downloader::downloadHttp()