Use native zip extension if possible (Xerte_Zip_Factory::factory(...)).

library/Xerte/Zip/Factory.php

@@ -0,0 +1,22 @@
+<?php
+
+/**
+ * Creates ZipFileobjects which abide to Xerte_Zip_Interface.
+ *
+ * @see zip_file
+ * @see Xerte_Zip_Interface
+ * @see export.php
+ */
+class Xerte_Zip_Factory {
+
+    public static function factory($tempfilename, $options) {
+        if (extension_loaded('zip')) {
+            return new Xerte_Zip_Native($tempfilename, $options);
+        } else {
+            // Use the legacy Zip thing - note it may hit memory limit(s). :-(
+            $zip = new zip_file($tempfilename);
+            $zip->set_options($options);
+            return $zip;
+        }
+    }
+}

library/Xerte/Zip/Interface.php

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+<?php
+
+
+/**
+ * functions required in an object which zips stuff up.
+ * These seem to be the ones used by export.php....
+ */
+interface Xerte_Zip_Interface {
+
+    /* array or single string file */
+    public function add_files($file_or_list);
+    public function set_options(array $array);
+
+    /* signal we've added everything and we're ready to package it all up */
+    public function create_archive();
+
+    /**
+     * write stuff out to the browser; provide $downloadName
+     * as the attachment file name that appears to the user 
+     * @param string $downloadName
+     */
+    public function download_file($downloadName);
+}

library/Xerte/Zip/Native.php

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+<?php
+
+/*
+ * To change this license header, choose License Headers in Project Properties.
+ * To change this template file, choose Tools | Templates
+ * and open the template in the editor.
+ */
+
+/**
+ * Description of Native
+ *
+ * @author david
+ */
+class Xerte_Zip_Native implements Xerte_Zip_Interface {
+    /* @var $zip ZipArchive */
+
+    private $zip = null;
+    public $error = array();
+
+    /* @var $filename string file path to where the zip thing is */
+    private $filename = null;
+
+    public function __construct($filename, $options) {
+        _debug("Welcome");
+        $this->filename = $filename;
+        $this->options = $options;
+        $this->zip = new ZipArchive();
+
+        $ok = $this->zip->open($filename, ZipArchive::CREATE | ZipArchive::OVERWRITE);
+        if (!$ok) {
+            $this->error[] = "Can't read $filename / create archive / overwrite archive";
+            error_log("Failed to create zip : $filename, $ok");
+            throw new Exception("Failed to create Zip: $filename");
+        }
+    }
+
+    public function add_files($things) {
+
+        if (!is_array($things)) {
+            $things = array($things);
+        }
+
+        foreach ($things as $thing) {
+            $localName = $thing;
+            if (isset($this->options['basedir'])) {
+                $localName = $thing;
+                $thing = $this->options['basedir'] . DIRECTORY_SEPARATOR . $thing;
+            }
+            _debug("Adding $localName (from: $thing) to zip");
+            $this->zip->addFile($thing, $localName);
+        }
+    }
+
+    public function set_options(array $options) {
+
+    }
+
+    public function create_archive() {
+        $this->zip->close();
+    }
+
+    public function download_file($downloadFilename) {
+        $fp = fopen($this->filename, 'rb');
+        $downloadFilename = preg_replace('/[^-_a-z0-9\.]/i', '', $downloadFilename);
+
+        header("Content-Type: application/zip");
+        header("Pragma: public");
+        header('Content-disposition: attachment; filename="' . $downloadFilename . '.zip"');
+        //header("Cache-Control: no-cache, must-revalidate, post-check=0, pre-check=0");
+        //header("Expires: Sat, 01 Jan 2000 12:00:00 GMT");
+        header("Content-Transfer-Encoding: binary");
+        $filesize = filesize($this->filename);
+
+        header("Content-Length: {$filesize}");
+
+        while (!feof($fp)) {
+            echo fread($fp, 8192);
+        }
+        //$bytes = fpassthru($fp);
+        _debug("Wrote : {$filesize} . bytes ... hopefully");
+        fclose($fp);
+    }
+
+}