[VarDumper] Fix FFICaster test to be platform-adaptable

Tests/Caster/FFICasterTest.php

@@ -12,6 +12,7 @@
 namespace Symfony\Component\VarDumper\Tests\Caster;
 
 use PHPUnit\Framework\TestCase;
+use Symfony\Component\VarDumper\Caster\FFICaster;
 use Symfony\Component\VarDumper\Test\VarDumperTestTrait;
 
 /**
@@ -23,6 +24,11 @@ class FFICasterTest extends TestCase
 {
  use VarDumperTestTrait;
 
+ /**
+ * @see FFICaster::MAX_STRING_LENGTH
+ */
+ private const MAX_STRING_LENGTH = 255;
+
  protected function setUp(): void
  {
  if (\in_array(\PHP_SAPI, ['cli', 'phpdbg'], true) && 'preload' === \ini_get('ffi.enable')) {
@@ -172,17 +178,24 @@ public function testCastCuttedPointerToChar()
  {
  $actualMessage = str_repeat('Hello World!', 30)."\0";
  $actualLength = \strlen($actualMessage);
-
- $expectedMessage = 'Hello World!Hello World!Hello World!Hello World!'
- .'Hello World!Hello World!Hello World!Hello World!Hello World!Hel'
- .'lo World!Hello World!Hello World!Hello World!Hello World!Hello '
- .'World!Hello World!Hello World!Hello World!Hello World!Hello Wor'
- .'ld!Hello World!Hel';
+ $expectedMessage = substr($actualMessage, 0, self::MAX_STRING_LENGTH);
 
  $string = \FFI::cdef()->new('char['.$actualLength.']');
  $pointer = \FFI::addr($string[0]);
  \FFI::memcpy($pointer, $actualMessage, $actualLength);
 
+ // the max length is platform-dependent and can be less than 255,
+ // so we need to cut the expected message to the maximum length
+ // allowed by pages size of the current system
+ $ffi = \FFI::cdef(<<<C
+ size_t zend_get_page_size(void);
+ C);
+
+ $pageSize = $ffi->zend_get_page_size();
+ $start = $ffi->cast('uintptr_t', $ffi->cast('char*', $pointer))->cdata;
+ $max = min(self::MAX_STRING_LENGTH, ($start | ($pageSize - 1)) - $start);
+ $expectedMessage = substr($expectedMessage, 0, $max);
+
  $this->assertDumpEquals(<<<PHP
  FFI\CData<char*> size 8 align 8 {
  cdata: "$expectedMessage"…