reduce memory usage when decoding files

[ericLemanissier]

When decoding attached files, passing the whole content of the file to imap_base64 or base64_decode leads to allocating the memory for the whole base 64 decoded file while the binary content of the file is still in memory. This leads easily to Out of memory error on limited resources servers. Using .stream_filter_append to decode the file while writing it in a temporary file uses much less memory. The content of the decoded file is then simply read from the file

[greezybacon]

I think you probably meant to build in more safeguards in the stream handler. The system should make its best effort to provide base64 decoding if the stream system and temp folder write fail. Perhaps it should be written like:

if (strlen($text) > (1 << 20)) {
    try {
        if (!($temp = tempnam(sys_get_temp_dir(), 'attachments'))
            || !($f = fopen($temp, 'w'))
        ) {
            throw new Exception();
        }
        $s_filter = stream_filter_append($f, 'convert.base64-decode',STREAM_FILTER_WRITE);
        if (!fwrite($f, $text))
            throw new Exception();
        stream_filter_remove($s_filter); 
        fclose($f);
        if (!($f = fopen($temp, 'r')) || !($text = fread($f, filesize($temp)))
            throw new Exception();
        fclose($f);
        unlink($temp);
        break;
    }
    catch (Exception $e) {
        // Noop. Fall through to imap_base64 method below
        @fclose($f);
        @unlink($temp);
    }
}
// imap_base64 implies strict mode. If it refuses to decode the
// data, then fallback to base64_decode in non-strict mode
$text = (($conv=imap_base64($text))) ? $conv : base64_decode($text);
break;

[ericLemanissier]

That's just it, thanks !