Check headers sent before sending PHP response

If the response contents has been sent before an error occurs, PHP
triggers the warning "Cannot modify header information - headers already sent"

This change ensure that the error message is echoed, while it's impossible
to change the HTTP status code and headers.

ErrorHandler.php

@@ -13,6 +13,7 @@ namespace Symfony\Component\Debug;
 
 use Symfony\Component\Debug\Exception\FatalErrorException;
 use Symfony\Component\Debug\Exception\ContextErrorException;
+use Symfony\Component\Debug\Exception\DummyException;
 use Psr\Log\LoggerInterface;
 
 /**
@@ -125,7 +126,34 @@ class ErrorHandler
                 require __DIR__.'/Exception/ContextErrorException.php';
             }
 
-            throw new ContextErrorException(sprintf('%s: %s in %s line %d', isset($this->levels[$level]) ? $this->levels[$level] : $level, $message, $file, $line), 0, $level, $file, $line, $context);
+            $exception = new ContextErrorException(sprintf('%s: %s in %s line %d', isset($this->levels[$level]) ? $this->levels[$level] : $level, $message, $file, $line), 0, $level, $file, $line, $context);
+
+            // Exceptions thrown from error handlers are sometimes not caught by the exception
+            // handler, so we invoke it directly (https://bugs.php.net/bug.php?id=54275)
+            $exceptionHandler = set_exception_handler(function () {});
+            restore_exception_handler();
+
+            if (is_array($exceptionHandler) && $exceptionHandler[0] instanceof ExceptionHandler) {
+                $exceptionHandler[0]->handle($exception);
+
+                if (!class_exists('Symfony\Component\Debug\Exception\DummyException')) {
+                    require __DIR__.'/Exception/DummyException.php';
+                }
+
+                // we must stop the PHP script execution, as the exception has
+                // already been dealt with, so, let's throw an exception that
+                // will be caught by a dummy exception handler
+                set_exception_handler(function (\Exception $e) use ($exceptionHandler) {
+                    if (!$e instanceof DummyException) {
+                        // happens if our dummy exception is caught by a
+                        // catch-all from user code, in which case, let's the
+                        // current handler handle this "new" exception
+                        call_user_func($exceptionHandler, $e);
+                    }
+                });
+
+                throw new DummyException();
+            }
         }
 
         return false;
@@ -158,7 +186,7 @@ class ErrorHandler
         }
 
         // get current exception handler
-        $exceptionHandler = set_exception_handler(function() {});
+        $exceptionHandler = set_exception_handler(function () {});
         restore_exception_handler();
 
         if (is_array($exceptionHandler) && $exceptionHandler[0] instanceof ExceptionHandler) {

Exception/ContextErrorException.php

@@ -27,7 +27,7 @@ class ContextErrorException extends \ErrorException
     }
 
     /**
-     * @return array Array of variables that existed when the exception occured
+     * @return array Array of variables that existed when the exception occurred
      */
     public function getContext()
     {

Exception/DummyException.php

@@ -0,0 +1,21 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Debug\Exception;
+
+/**
+ * Used to stop execution of a PHP script after handling a fatal error.
+ *
+ * @author Fabien Potencier <fabien@symfony.com>
+ */
+class DummyException extends \ErrorException
+{
+}

Exception/FlattenException.php

@@ -249,7 +249,7 @@ class FlattenException
                 if ($level > 10) {
                     $result[$key] = array('array', '*DEEP NESTED ARRAY*');
                 } else {
-                    $result[$key] = array('array', $this->flattenArgs($value, ++$level));
+                    $result[$key] = array('array', $this->flattenArgs($value, $level + 1));
                 }
             } elseif (null === $value) {
                 $result[$key] = array('null', null);

ExceptionHandler.php

@@ -91,9 +91,11 @@ class ExceptionHandler
             $exception = FlattenException::create($exception);
         }
 
-        header(sprintf('HTTP/1.0 %s', $exception->getStatusCode()));
-        foreach ($exception->getHeaders() as $name => $value) {
-            header($name.': '.$value, false);
+        if (!headers_sent()) {
+            header(sprintf('HTTP/1.0 %s', $exception->getStatusCode()));
+            foreach ($exception->getHeaders() as $name => $value) {
+                header($name.': '.$value, false);
+            }
         }
 
         echo $this->decorate($this->getContent($exception), $this->getStylesheet($exception));

LICENSE

@@ -1,4 +1,4 @@
-Copyright (c) 2004-2013 Fabien Potencier
+Copyright (c) 2004-2014 Fabien Potencier
 
 Permission is hereby granted, free of charge, to any person obtaining a copy
 of this software and associated documentation files (the "Software"), to deal

Tests/ErrorHandlerTest.php

@@ -12,6 +12,7 @@
 namespace Symfony\Component\Debug\Tests;
 
 use Symfony\Component\Debug\ErrorHandler;
+use Symfony\Component\Debug\Exception\DummyException;
 
 /**
  * ErrorHandlerTest
@@ -20,30 +21,133 @@ use Symfony\Component\Debug\ErrorHandler;
  */
 class ErrorHandlerTest extends \PHPUnit_Framework_TestCase
 {
+    /**
+     * @var int Error reporting level before running tests.
+     */
+    protected $errorReporting;
+
+    /**
+     * @var string Display errors setting before running tests.
+     */
+    protected $displayErrors;
+
+    public function setUp()
+    {
+        $this->errorReporting = error_reporting(E_ALL | E_STRICT);
+        $this->displayErrors = ini_get('display_errors');
+        ini_set('display_errors', '1');
+    }
+
+    public function tearDown()
+    {
+        ini_set('display_errors', $this->displayErrors);
+        error_reporting($this->errorReporting);
+    }
+
     public function testCompileTimeError()
     {
-        // the ContextErrorException must not be loaded for this test to work
+        // the ContextErrorException must not be loaded to test the workaround
+        // for https://bugs.php.net/bug.php?id=65322.
         if (class_exists('Symfony\Component\Debug\Exception\ContextErrorException', false)) {
             $this->markTestSkipped('The ContextErrorException class is already loaded.');
         }
-    
-        $handler = ErrorHandler::register(E_ALL | E_STRICT);
-        $displayErrors = ini_get('display_errors');
-        ini_set('display_errors', '1');
 
+        $exceptionHandler = $this->getMock('Symfony\Component\Debug\ExceptionHandler', array('handle'));
+
+        // the following code forces some PHPUnit classes to be loaded
+        // so that they will be available in the exception handler
+        // as they won't be autoloaded by PHP
+        class_exists('PHPUnit_Framework_MockObject_Invocation_Object');
+        $this->assertInstanceOf('stdClass', new \stdClass());
+        $this->assertEquals(1, 1);
+        $this->assertStringStartsWith('foo', 'foobar');
+        $this->assertArrayHasKey('bar', array('bar' => 'foo'));
+
+        $that = $this;
+        $exceptionCheck = function ($exception) use ($that) {
+            $that->assertInstanceOf('Symfony\Component\Debug\Exception\ContextErrorException', $exception);
+            $that->assertEquals(E_STRICT, $exception->getSeverity());
+            $that->assertEquals(2, $exception->getLine());
+            $that->assertStringStartsWith('Runtime Notice: Declaration of _CompileTimeError::foo() should be compatible with', $exception->getMessage());
+            $that->assertArrayHasKey('bar', $exception->getContext());
+        };
+
+        $exceptionHandler->expects($this->once())
+            ->method('handle')
+            ->will($this->returnCallback($exceptionCheck))
+        ;
+
+        ErrorHandler::register();
+        set_exception_handler(array($exceptionHandler, 'handle'));
+
+        // dummy variable to check for in error handler.
+        $bar = 123;
+
+        // trigger compile time error
         try {
-            // trigger compile time error
             eval(<<<'PHP'
 class _BaseCompileTimeError { function foo() {} }
 class _CompileTimeError extends _BaseCompileTimeError { function foo($invalid) {} }
 PHP
             );
-        } catch(\Exception $e) {
+        } catch (DummyException $e) {
             // if an exception is thrown, the test passed
         }
 
-        ini_set('display_errors', $displayErrors);
         restore_error_handler();
+        restore_exception_handler();
+    }
+
+    public function testNotice()
+    {
+        $exceptionHandler = $this->getMock('Symfony\Component\Debug\ExceptionHandler', array('handle'));
+        set_exception_handler(array($exceptionHandler, 'handle'));
+
+        $that = $this;
+        $exceptionCheck = function ($exception) use ($that) {
+            $that->assertInstanceOf('Symfony\Component\Debug\Exception\ContextErrorException', $exception);
+            $that->assertEquals(E_NOTICE, $exception->getSeverity());
+            $that->assertEquals(__LINE__ + 40, $exception->getLine());
+            $that->assertEquals(__FILE__, $exception->getFile());
+            $that->assertRegexp('/^Notice: Undefined variable: (foo|bar)/', $exception->getMessage());
+            $that->assertArrayHasKey('foobar', $exception->getContext());
+
+            $trace = $exception->getTrace();
+            $that->assertEquals(__FILE__, $trace[0]['file']);
+            $that->assertEquals('Symfony\Component\Debug\ErrorHandler', $trace[0]['class']);
+            $that->assertEquals('handle', $trace[0]['function']);
+            $that->assertEquals('->', $trace[0]['type']);
+
+            $that->assertEquals(__FILE__, $trace[1]['file']);
+            $that->assertEquals(__CLASS__, $trace[1]['class']);
+            $that->assertEquals('triggerNotice', $trace[1]['function']);
+            $that->assertEquals('::', $trace[1]['type']);
+
+            $that->assertEquals(__CLASS__, $trace[2]['class']);
+            $that->assertEquals('testNotice', $trace[2]['function']);
+            $that->assertEquals('->', $trace[2]['type']);
+        };
+
+        $exceptionHandler->expects($this->once())
+            ->method('handle')
+            ->will($this->returnCallback($exceptionCheck));
+        ErrorHandler::register();
+
+        try {
+            self::triggerNotice($this);
+        } catch (DummyException $e) {
+            // if an exception is thrown, the test passed
+        }
+
+        restore_error_handler();
+    }
+
+    // dummy function to test trace in error handler.
+    private static function triggerNotice($that)
+    {
+        // dummy variable to check for in error handler.
+        $foobar = 123;
+        $that->assertSame('', $foo.$foo.$bar);
     }
 
     public function testConstruct()
@@ -95,7 +199,7 @@ PHP
         $logger = $this->getMock('Psr\Log\LoggerInterface');
 
         $that = $this;
-        $warnArgCheck = function($message, $context) use ($that) {
+        $warnArgCheck = function ($message, $context) use ($that) {
             $that->assertEquals('foo', $message);
             $that->assertArrayHasKey('type', $context);
             $that->assertEquals($context['type'], ErrorHandler::TYPE_DEPRECATION);

Tests/Exception/FlattenExceptionTest.php

@@ -113,7 +113,7 @@ class FlattenExceptionTest extends \PHPUnit_Framework_TestCase
 
         $this->assertEquals($exception->getMessage(), $flattened->getMessage(), 'The message is copied from the original exception.');
         $this->assertEquals($exception->getCode(), $flattened->getCode(), 'The code is copied from the original exception.');
-        $this->assertEquals(get_class($exception), $flattened->getClass(), 'The class is set to the class of the original exception');
+        $this->assertInstanceOf($flattened->getClass(), $exception, 'The class is set to the class of the original exception');
 
     }
 

Tests/ExceptionHandlerTest.php

@@ -64,6 +64,6 @@ class ExceptionHandlerTest extends \PHPUnit_Framework_TestCase
     public function testNestedExceptions()
     {
         $handler = new ExceptionHandler(true);
-        $response = $handler->createResponse(new \RuntimeException('Foo', null, new \RuntimeException('Bar')));
+        $response = $handler->createResponse(new \RuntimeException('Foo', 0, new \RuntimeException('Bar')));
     }
 }