add php native gzdecode()

include/functions.php

@@ -3934,9 +3934,121 @@
 	}
 
 	if (!function_exists('gzdecode')) {
-		function gzdecode($string) { // no support for 2nd argument
+		/* function gzdecode($string) { // no support for 2nd argument
 			return file_get_contents('compress.zlib://data:who/cares;base64,'.
 				base64_encode($string));
+		} */
+
+
+		function gzdecode($data, &$filename = '', &$error = '', $maxlength = null) {
+		    $len = strlen($data);
+		    if ($len < 18 || strcmp(substr($data,0,2),"\x1f\x8b")) {
+		        $error = "Not in GZIP format.";
+		        return null;  // Not GZIP format (See RFC 1952)
+		    }
+		    $method = ord(substr($data,2,1));  // Compression method
+		    $flags  = ord(substr($data,3,1));  // Flags
+		    if ($flags & 31 != $flags) {
+		        $error = "Reserved bits not allowed.";
+		        return null;
+		    }
+		    // NOTE: $mtime may be negative (PHP integer limitations)
+		    $mtime = unpack("V", substr($data,4,4));
+		    $mtime = $mtime[1];
+		    $xfl   = substr($data,8,1);
+		    $os    = substr($data,8,1);
+		    $headerlen = 10;
+		    $extralen  = 0;
+		    $extra     = "";
+		    if ($flags & 4) {
+		        // 2-byte length prefixed EXTRA data in header
+		        if ($len - $headerlen - 2 < 8) {
+		            return false;  // invalid
+		        }
+		        $extralen = unpack("v",substr($data,8,2));
+		        $extralen = $extralen[1];
+		        if ($len - $headerlen - 2 - $extralen < 8) {
+		            return false;  // invalid
+		        }
+		        $extra = substr($data,10,$extralen);
+		        $headerlen += 2 + $extralen;
+		    }
+		    $filenamelen = 0;
+		    $filename = "";
+		    if ($flags & 8) {
+		        // C-style string
+		        if ($len - $headerlen - 1 < 8) {
+		            return false; // invalid
+		        }
+		        $filenamelen = strpos(substr($data,$headerlen),chr(0));
+		        if ($filenamelen === false || $len - $headerlen - $filenamelen - 1 < 8) {
+		            return false; // invalid
+		        }
+		        $filename = substr($data,$headerlen,$filenamelen);
+		        $headerlen += $filenamelen + 1;
+		    }
+		    $commentlen = 0;
+		    $comment = "";
+		    if ($flags & 16) {
+		        // C-style string COMMENT data in header
+		        if ($len - $headerlen - 1 < 8) {
+		            return false;    // invalid
+		        }
+		        $commentlen = strpos(substr($data,$headerlen),chr(0));
+		        if ($commentlen === false || $len - $headerlen - $commentlen - 1 < 8) {
+		            return false;    // Invalid header format
+		        }
+		        $comment = substr($data,$headerlen,$commentlen);
+		        $headerlen += $commentlen + 1;
+		    }
+		    $headercrc = "";
+		    if ($flags & 2) {
+		        // 2-bytes (lowest order) of CRC32 on header present
+		        if ($len - $headerlen - 2 < 8) {
+		            return false;    // invalid
+		        }
+		        $calccrc = crc32(substr($data,0,$headerlen)) & 0xffff;
+		        $headercrc = unpack("v", substr($data,$headerlen,2));
+		        $headercrc = $headercrc[1];
+		        if ($headercrc != $calccrc) {
+		            $error = "Header checksum failed.";
+		            return false;    // Bad header CRC
+		        }
+		        $headerlen += 2;
+		    }
+		    // GZIP FOOTER
+		    $datacrc = unpack("V",substr($data,-8,4));
+		    $datacrc = sprintf('%u',$datacrc[1] & 0xFFFFFFFF);
+		    $isize = unpack("V",substr($data,-4));
+		    $isize = $isize[1];
+		    // decompression:
+		    $bodylen = $len-$headerlen-8;
+		    if ($bodylen < 1) {
+		        // IMPLEMENTATION BUG!
+		        return null;
+		    }
+		    $body = substr($data,$headerlen,$bodylen);
+		    $data = "";
+		    if ($bodylen > 0) {
+		        switch ($method) {
+		        case 8:
+		            // Currently the only supported compression method:
+		            $data = gzinflate($body,$maxlength);
+		            break;
+		        default:
+		            $error = "Unknown compression method.";
+		            return false;
+		        }
+		    }  // zero-byte body content is allowed
+		    // Verifiy CRC32
+		    $crc   = sprintf("%u",crc32($data));
+		    $crcOK = $crc == $datacrc;
+		    $lenOK = $isize == strlen($data);
+		    if (!$lenOK || !$crcOK) {
+		        $error = ( $lenOK ? '' : 'Length check FAILED. ') . ( $crcOK ? '' : 'Checksum FAILED.');
+		        return false;
+		    }
+		    return $data;
 		}
 	}