Why PHP's gzuncompress() function can go wrong?

Question

PHP has its own function to work with gzip archives. I wrote the following code:

error_reporting(E_ALL);
$f = file_get_contents(\'http://spiderbites.nytimes.         


        

Answer 1

Or you could just use the right decompression function, gzdecode().

Answer 2

Note that gzuncompress() may not decompress some compressed strings and return a Data Error.

The problem could be that the outside compressed string has a CRC32 checksum at the end of the file instead of Adler-32, like PHP expects.

(http://php.net/manual/en/function.gzuncompress.php#79042)

That could be an option of why it does not work.

Try with his code:

function gzuncompress_crc32($data) {
     $f = tempnam('/tmp', 'gz_fix');
     file_put_contents($f, "\x1f\x8b\x08\x00\x00\x00\x00\x00" . $data);
     return file_get_contents('compress.zlib://' . $f);
}

Modify your code in this:

error_reporting(E_ALL);
$f = file_get_contents('http://spiderbites.nytimes.com/sitemaps/www.nytimes.com/sitemap.xml.gz');
echo $f;
$f = gzuncompress_crc32($f);
echo "<hr>";
echo $f;

As far as I have tested locally, it does not give the error anymore.