这段代码有什么问题：来自远程压缩文件的file_get_contents和解压缩到本地目录

The purpose of this code is to pull upgrade.zip from a central server, extract it and place it in a folder on the resident server. I get no errors, it just results in the die("!There was a problem. Please try again!");

require('../../../wp-blog-header.php');

function openZip($file_to_open) { 
    global $target;  
    $zip = new ZipArchive();  
    $x = $zip->open($file_to_open);  
    if($x === true) {  
        $zip->extractTo($target);  
        $zip->close();  
        unlink($file_to_open);  
    } else {  
        die("!There was a problem. Please try again!");  
    }  
} 

$payload = file_get_contents('http://myserver.com/upgrade.zip');
if(isset($payload)) 
    {
    $filename = 'upgrade.zip';
    $source = file_get_contents('http://myserver.com/upgrade.zip');
    $target = ABSPATH.'wp-content/themes/mytheme/';

    // permission settings for newly created folders
    $chmod = 0755;  

    $saved_file_location = $target . $filename;

openZip($saved_file_location);

}

You get the contents of the remote zip file into a string... but you never save it anywhere.

You should investigate the return value from $zip->open(). It may be any of the following:

ZIPARCHIVE::ER_EXISTS 
ZIPARCHIVE::ER_INCONS 
ZIPARCHIVE::ER_INVAL 
ZIPARCHIVE::ER_MEMORY 
ZIPARCHIVE::ER_NOENT 
ZIPARCHIVE::ER_NOZIP 
ZIPARCHIVE::ER_OPEN 
ZIPARCHIVE::ER_READ 
ZIPARCHIVE::ER_SEEK 

Also, why not try to open the downloaded zip-file manually using your favourite unzip program to check if the file is indeed valid?