我通过阅读我在原帖中链接的gzdecode
页面上的评论找到了答案。其中一个用户Aaron G提供了一个实现方法,它可以正常工作:
<?php
function gzdecode($data) {
$len = strlen($data);
if ($len < 18 || strcmp(substr($data,0,2),"\x1f\x8b")) {
return null;
}
$method = ord(substr($data,2,1));
$flags = ord(substr($data,3,1));
if ($flags & 31 != $flags) {
return null;
}
$mtime = unpack("V", substr($data,4,4));
$mtime = $mtime[1];
$xfl = substr($data,8,1);
$os = substr($data,8,1);
$headerlen = 10;
$extralen = 0;
$extra = "";
if ($flags & 4) {
if ($len - $headerlen - 2 < 8) {
return false;
}
$extralen = unpack("v",substr($data,8,2));
$extralen = $extralen[1];
if ($len - $headerlen - 2 - $extralen < 8) {
return false;
}
$extra = substr($data,10,$extralen);
$headerlen += 2 + $extralen;
}
$filenamelen = 0;
$filename = "";
if ($flags & 8) {
if ($len - $headerlen - 1 < 8) {
return false;
}
$filenamelen = strpos(substr($data,8+$extralen),chr(0));
if ($filenamelen === false || $len - $headerlen - $filenamelen - 1 < 8) {
return false;
}
$filename = substr($data,$headerlen,$filenamelen);
$headerlen += $filenamelen + 1;
}
$commentlen = 0;
$comment = "";
if ($flags & 16) {
if ($len - $headerlen - 1 < 8) {
return false;
}
$commentlen = strpos(substr($data,8+$extralen+$filenamelen),chr(0));
if ($commentlen === false || $len - $headerlen - $commentlen - 1 < 8) {
return false;
}
$comment = substr($data,$headerlen,$commentlen);
$headerlen += $commentlen + 1;
}
$headercrc = "";
if ($flags & 1) {
if ($len - $headerlen - 2 < 8) {
return false;
}
$calccrc = crc32(substr($data,0,$headerlen)) & 0xffff;
$headercrc = unpack("v", substr($data,$headerlen,2));
$headercrc = $headercrc[1];
if ($headercrc != $calccrc) {
return false;
}
$headerlen += 2;
}
$datacrc = unpack("V",substr($data,-8,4));
$datacrc = $datacrc[1];
$isize = unpack("V",substr($data,-4));
$isize = $isize[1];
$bodylen = $len-$headerlen-8;
if ($bodylen < 1) {
return null;
}
$body = substr($data,$headerlen,$bodylen);
$data = "";
if ($bodylen > 0) {
switch ($method) {
case 8:
$data = gzinflate($body);
break;
default:
return false;
}
} else {
}
if ($isize != strlen($data) || crc32($data) != $datacrc) {
return false;
}
return $data;
}
?>