RecursiveDirectoryIterator throws UnexpectedValueException on "Too many open files"

Question

The following code:

$zip = new ZipArchive();

if ($zip->open('./archive.zip', ZIPARCHIVE::CREATE) !== TRUE) {
    die ("Could not open archive");
}

$iterator = new RecursiveIteratorIterator(new RecursiveDirectoryIterator("./folder/"));

foreach ($iterator as $key => $value) {
  try {
    $zip->addFile(realpath($key), $key);
    echo "'$key' successfully added.\n";
  } catch (Exception $e) {
    echo "ERROR: Could not add the file '$key': $e\n";
  }
}

$zip->close();

Throws the following exception if there are too many files in a sub-folder which you're trying to iterate over:

Uncaught exception 'UnexpectedValueException' with message 'RecursiveDirectoryIterator::__construct(./some/path/): failed to open dir: Too many open files' in /some/other/path/zip.php:24
Stack trace:
#0 [internal function]: RecursiveDirectoryIterator->__construct('./some/path/')
#1 /some/other/path/zip.php(24): RecursiveDirectoryIterator->getChildren()
#2 {main}
thrown in /some/other/path/zip.php on line 24

How can you successfully iterate over a large amount of folders and files without experiencing this exception?

Answer 1

Simply by converting the iterator to an array with the iterator_to_array function, it seems like you can iterate over as many files as you'd like:

$iterator = new RecursiveIteratorIterator(new RecursiveDirectoryIterator("./folder/"));
$files = iterator_to_array($iterator, true);

// iterate over the directory
// add each file found to the archive
foreach ($files as $key => $value) {
  try {
    $zip->addFile(realpath($key), $key);
    echo "'$key' successfully added.\n";
  } catch (Exception $e) {
    echo "ERROR: Could not add the file '$key': $e\n";
  }
}