PHP ZipArchive stopped working - php

Question

I have a script which takes a zipped CSV file, unzips it, and removes duplicate entries. It was mostly working, until I moved the unzip code into a function. Now it fails to unzip the .zip file, but doesn't show an error.
Checked file/folder permissions, everything is 777 on dev machine.
<?php
//
//huge memory limit for large files
$old = ini_set('memory_limit', '8192M');
//
//create a string like the filename
$base_filename = 'csv-zip-file'.date('m').'_'.date('d').'_'.date('Y');
//
//if the file exists ...
//unzip it
//read it to an array
//remove duplicates
//save it as a new csv
if (file_exists($base_filename.'.zip')) {
$zip_filename = $base_filename.'.zip';
echo "The file <strong>$zip_filename</strong> exists<br>";
unzip($zip_filename);
$csv = csv_to_array();
$csv = unique_multidim_array($csv,"Project Id");
var_dump($csv);
} else {
echo "The file <strong>$base_filename.zip</strong> does not exist";
}
function unzip($file_to_unzip) {
$zip=new ZipArchive();
if($zip->open($file_to_unzip)==TRUE) {
$address=__DIR__;
$zip->extractTo($address);
$res=$zip->close();
echo 'ok';
}
else{
echo 'failed';
}
}
function unique_multidim_array($array, $key) {
$temp_array = array();
$i = 0;
$key_array = array();
foreach($array as $val) {
if (!in_array($val[$key], $key_array)) {
$key_array[$i] = $val[$key];
$temp_array[$i] = $val;
}
$i++;
}
return $temp_array;
}
function csv_to_array () {
// global $filename;
global $base_filename;
$rows = array_map('str_getcsv', file($base_filename.'.csv'));
//using array_pop to remove the copyright on final row
array_pop($rows);
$header = array_shift($rows);
$csv = array();
foreach ($rows as $row) {
$csv[] = array_combine($header, $row);
}
return $csv;
}

Answer 1

Interesting problem you have here.
Output $file_to_unzip right inside the function.
Does $zip->* have an last_error or last_response method? See
what the ZipArchive class IS returning.
Do you have access to the php error logs? Let's look there for any output.