Issue #1750228 by Boobaa, corvus_ch: Fixed Adding a new language with empty .po file and locale.module enabled throws a fatal error.

core/lib/Drupal/Component/Gettext/PoStreamReader.php

@@ -230,6 +230,10 @@ class PoStreamReader implements PoStreamInterface, PoReaderInterface {
    */
   private function readHeader() {
     $item = $this->readItem();
+    // Handle the case properly when the .po file is empty (0 bytes).
+    if (!$item) {
+      return;
+    }
     $header = new PoHeader;
     $header->setFromString(trim($item->getTranslation()));
     $this->_header = $header;

core/modules/locale/lib/Drupal/locale/Gettext.php

@@ -10,6 +10,7 @@ namespace Drupal\locale;
 use Drupal\Component\Gettext\PoStreamReader;
 use Drupal\Component\Gettext\PoMemoryWriter;
 use Drupal\locale\PoDatabaseWriter;
+use Exception;
 
 /**
  * Static class providing Drupal specific Gettext functionality.

core/modules/locale/lib/Drupal/locale/Tests/LocaleImportFunctionalTest.php

@@ -76,6 +76,13 @@ class LocaleImportFunctionalTest extends WebTestBase {
     $skip_message = format_plural(2, 'A translation string was skipped because of disallowed or malformed HTML. <a href="@url">See the log</a> for details.', '@count translation strings were skipped because of disallowed or malformed HTML. <a href="@url">See the log</a> for details.', array('@url' => url('admin/reports/dblog')));
     $this->assertRaw($skip_message, t('Unsafe strings were skipped.'));
 
+    // Try importing a zero byte sized .po file.
+    $this->importPoFile($this->getEmptyPoFile(), array(
+      'langcode' => 'fr',
+    ));
+
+    // The import should have created 0 string and rejected 0.
+    $this->assertRaw(t('The translation was successfully imported. There are %number newly created translated strings, %update strings were updated and %delete strings were removed.', array('%number' => 0, '%update' => 0, '%delete' => 0)), 'The empty translation file was successfully imported.');
 
     // Try importing a .po file which doesn't exist.
     $name = $this->randomName(16);
@@ -338,6 +345,13 @@ msgstr "dimanche"
 EOF;
   }
 
+  /**
+   * Helper function that returns a empty .po file.
+   */
+  function getEmptyPoFile() {
+    return '';
+  }
+
   /**
    * Helper function that returns a bad .po file.
    */

core/modules/locale/locale.bulk.inc

@@ -496,13 +496,17 @@ function locale_translate_batch_finished($success, $results) {
     $additions = $updates = $deletes = $skips = 0;
     drupal_set_message(format_plural(count($results['files']), 'One translation file imported.', '@count translation files imported.'));
     $skipped_files = array();
-    foreach ($results['stats'] as $filepath => $report) {
-      $additions += $report['additions'];
-      $updates += $report['updates'];
-      $deletes += $report['deletes'];
-      $skips += $report['skips'];
-      if ($report['skips'] > 0) {
-        $skipped_files[] = $filepath;
+    // If there are no results and/or no stats (eg. coping with an empty .po
+    // file), simply do nothing.
+    if ($results && isset($results['stats'])) {
+      foreach ($results['stats'] as $filepath => $report) {
+        $additions += $report['additions'];
+        $updates += $report['updates'];
+        $deletes += $report['deletes'];
+        $skips += $report['skips'];
+        if ($report['skips'] > 0) {
+          $skipped_files[] = $filepath;
+        }
       }
     }
     drupal_set_message(t('The translation was successfully imported. There are %number newly created translated strings, %update strings were updated and %delete strings were removed.', array('%number' => $additions, '%update' => $updates, '%delete' => $deletes)));