Issue #2867336 by mbovan, jcnventura, Berdir, hchonov, gabesullice,...

Issue #2867336 by mbovan, jcnventura, Berdir, hchonov, gabesullice, jonathanshaw: File size validator should only respect the explicitly configured maximum file size

core/modules/file/src/Plugin/Field/FieldType/FileItem.php

@@ -180,7 +180,7 @@ public function fieldSettingsForm(array $form, FormStateInterface $form_state) {
       '#type' => 'textfield',
       '#title' => $this->t('Maximum upload size'),
       '#default_value' => $settings['max_filesize'],
-      '#description' => $this->t('Enter a value like "512" (bytes), "80 KB" (kilobytes) or "50 MB" (megabytes) in order to restrict the allowed file size. If left empty the file sizes will be limited only by PHP\'s maximum post and file upload sizes (current limit <strong>%limit</strong>).', ['%limit' => format_size(Environment::getUploadMaxSize())]),
+      '#description' => $this->t('Enter a value like "512" (bytes), "80 KB" (kilobytes) or "50 MB" (megabytes) in order to restrict the allowed file size. If left empty the file sizes could be limited only by PHP\'s maximum post and file upload sizes (current limit <strong>%limit</strong>).', ['%limit' => format_size(Environment::getUploadMaxSize())]),
       '#size' => 10,
       '#element_validate' => [[static::class, 'validateMaxFilesize']],
       '#weight' => 5,

core/modules/file/src/Plugin/Validation/Constraint/FileValidationConstraintValidator.php

@@ -2,6 +2,7 @@
 
 namespace Drupal\file\Plugin\Validation\Constraint;
 
+use Drupal\Component\Utility\Bytes;
 use Symfony\Component\Validator\Constraint;
 use Symfony\Component\Validator\ConstraintValidator;
 
@@ -23,6 +24,17 @@ public function validate($value, Constraint $constraint) {
     $file = $target->getValue();
     // Get the validators.
     $validators = $value->getUploadValidators();
+
+    // Always respect the configured maximum file size.
+    $field_settings = $value->getFieldDefinition()->getSettings();
+    if (array_key_exists('max_filesize', $field_settings)) {
+      $validators['file_validate_size'] = [Bytes::toNumber($field_settings['max_filesize'])];
+    }
+    else {
+      // Do not validate the file size if it is not set explicitly.
+      unset($validators['file_validate_size']);
+    }
+
     // Checks that a file meets the criteria specified by the validators.
     if ($errors = file_validate($file, $validators)) {
       foreach ($errors as $error) {