gzipped strings include header/metadata you can use to determine if a string is gzipped or not , but since gzcompress does not include that I found myself needing a way to determine if a string was compressed or not. After some research (and then improvements) i came up with this:
/**
* determines if a string is a gzipped string supporting strings
* encoded with either gzencode or gzcompress
*
* @param string $string the string to check for compression
* @return bool whether or not the string was compmressed
*/
function is_gzipped($string) {
return mb_strpos($string, "\x1f\x8b\x08", 'US-ASCII') === 0 && @gzuncompress($string) !== FALSE;
}
