commit 0631777c779599a8ee0634ca306f6dbec1bbcdae
Author: Bevan Wishart <bevan.wishart@gmail.com>
Date:   Sun Jun 14 09:43:08 2020 +1000

    870576-58.patch

diff --git a/core/modules/file/src/Plugin/Field/FieldType/FileItemMaxFileSizeValidator.php b/core/modules/file/src/Plugin/Field/FieldType/FileItemMaxFileSizeValidator.php
index d24c7958c7..35cda5051d 100644
--- a/core/modules/file/src/Plugin/Field/FieldType/FileItemMaxFileSizeValidator.php
+++ b/core/modules/file/src/Plugin/Field/FieldType/FileItemMaxFileSizeValidator.php
@@ -11,6 +11,15 @@ use Drupal\Core\StringTranslation\TranslatableMarkup;
  */
 class FileItemMaxFileSizeValidator {

+  /**
+   * Holds a string representing a byte size to be validated.
+   *
+   * @var string $size
+   *   A string size expressed as a number of bytes with optional SI
+   *   or IEC binary unit prefix (e.g. 2, 3K, 5MB, 10G, 6GiB, 8 bytes, 9mbytes).
+   */
+  private static $size;
+
   /**
    * Form API callback.
    *
@@ -22,21 +31,39 @@ class FileItemMaxFileSizeValidator {
    */
   public static function validateMaxFilesize($element, FormStateInterface $form_state) {

-    $size = self::stripSpacesFromString($element['#value']);
-    if (empty($size)) {
+    // Spaces are irrelevant to us. Bytes::toInt will process with or without
+    // them. Make our lives easier by just doing away with them.
+    self::$size = self::stripSpacesFromString($element['#value']);
+
+    // Having removed whitespace, if our string is now empty then the user
+    // either entered nothing or a string of whitespace. Accept both cases as
+    // valid.
+    if (empty(self::$size)) {
       return;
     }
-    if (self::stringIsNotAlphanumeric($size) ||
-      self::stringNotStartWithNumber($size) ||
-      self::hasNumbersFollowingAlphaCharInString($size) ||
-      // Theoretically the above validation should have prevented invalid data
-      // getting this far. Passing to toInt() for good measure.
-      !self::toIntCanParseString($size)) {
+
+    // Theoretically self::stringIsValidByteString() should perform strict
+    // enough validation. Passing the string to Bytes::toInt() for added
+    // precaution.
+    if (self::sizeIsValidByteString() || !self::toIntCanParseString()) {
       $translatable_markup = new TranslatableMarkup('The "@name" option must contain a valid value. You may either leave the text field empty or enter a string like "512" (bytes), "80 KB" (kilobytes) or "50 MB" (megabytes).', ['@name' => $element['#title']]);
       $form_state->setError($element, $translatable_markup);
     }
   }

+  /**
+   * Validate the given string looks like a byte size string.
+   *
+   * @return bool
+   */
+  private static function sizeIsValidByteString() {
+    return (
+      self::sizeIsNotAlphaNumeric() ||
+      self::sizeNotStartWithNumber() ||
+      self::sizeHasNumbersFollowingAlphaChar()
+    );
+  }
+
   /**
    * Strips spaces from a string of text.
    *
@@ -53,55 +80,43 @@ class FileItemMaxFileSizeValidator {
   /**
    * Determines that a string does not start with a number.
    *
-   * @param string $string
-   *   A string representing a size (5mb, 500GB etc)
-   *
    * @return bool
    *   TRUE if the string does not start with a numeric char, FALSE otherwise.
    */
-  private static function stringNotStartWithNumber($string) {
-    return !preg_match('/^\d/', $string);
+  private static function sizeNotStartWithNumber() {
+    return !preg_match('/^\d/', self::$size);
   }

   /**
    * Determines if a string has numberic chars following after alpha chars.
    *
-   * @param string $string
-   *   A string representing a size (5mb, 500GB etc)
-   *
    * @return bool
    *   TRUE if the string has numeric values following after alpha chars.
    */
-  private static function hasNumbersFollowingAlphaCharInString($string) {
-    return (bool) preg_match('/[a-zA-Z]+(\d+)/', $string);
+  private static function sizeHasNumbersFollowingAlphaChar() {
+    return (bool) preg_match('/[a-zA-Z]+(\d+)/', self::$size);
   }

   /**
    * Determines if a string contains non alphanumeric characters.
    *
-   * @param string $string
-   *   A string of various characters.
-   *
    * @return bool
    *   Returns TRUE if non alphanumeric characters are found.
    */
-  private static function stringIsNotAlphaNumeric($string) {
-    return (bool) !preg_match('/^[a-zA-Z0-9]+$/', $string);
+  private static function sizeIsNotAlphaNumeric() {
+    return (bool) !preg_match('/^[a-zA-Z0-9]+$/', self::$size);
   }

   /**
    * Determines if Bytes:toInt() is able to parse the given string.
    *
-   * @param string $string
-   *   A string representing a size (5mb, 500GB etc)
-   *
    * @return bool
    *   TRUE if string can be parsed by Bytes::toInt(), FALSE otherwise.
    */
-  private static function toIntCanParseString($string) {
+  private static function toIntCanParseString() {
     $valid = TRUE;
     try {
-      Bytes::toInt($string);
+      Bytes::toInt(self::$size);
     }
     catch (\Exception $e) {
       $valid = FALSE;