hhvm-fastcgi + nginx how to make it display fatal errors in the browser

Question

I've been playing with HHVM config file and I have yet to be able to make it output any fatal error to the browser. It displays E_NOTICE and E_WARNING but when any E_ERROR happens it leaves the page blank and the error only appears in the HHVM log file.

Is there a way to make it show in the browser?

My HHVM config file is as follow:

PidFile = /var/run/hhvm/pid

Log {
  Level = Warning
  AlwaysLogUnhandledExceptions = true
  RuntimeErrorReportingLevel = 8191
  UseLogFile = true
  UseSyslog = false
  File = /var/log/hhvm/error.log
  InjectedStackTrace = false
  NativeStackTrace = false
  Access {
    * {
      File = /var/log/hhvm/access.log
      Format = %h %l %u % t \"%r\" %>s %b
    }
  }
}

ErrorHandling {
  CallUserHandlerOnFatals = true
  NoInfiniteLoopDetection = false
  NoInfiniteRecursionDetection = false
  ThrowBadTypeExceptions = false
  ThrowNotices = false
  NoticeFrequency = 1    # 1 out of these many notices to log
  WarningFrequency = 1   # 1 out of these many warnings to log
  AssertActive = false
  AssertWarning = false
}

Debug {
  FullBacktrace = false
  ServerStackTrace = false
  ServerErrorMessage = false
  TranslateSource = false

  RecordInput = false
  ClearInputOnSuccess = true

  ProfilerOutputDir = /tmp

  CoreDumpReport = true
  CoreDumpReportDirectory = /tmp
}

Http {
  DefaultTimeout = 30 # in seconds
  SlowQueryThreshold = 5000 # in ms, log slow HTTP requests as errors
}

Mail {
  SendmailPath = sendmail -t -i
  ForceExtraParameters =
}

Preg {
 BacktraceLimit = 100000
 RecursionLimit = 100000
}

Repo {
  Central {
    Path = /var/log/hhvm/.hhvm.hhbc
  }
}

Eval {
  Jit = true
}

MySQL {
  TypedResults = false
  ReadOnly = false
  ConnectTimeout = 2000      # in ms
  ReadTimeout = 2000         # in ms
  SlowQueryThreshold = 2000  # in ms, log slow queries as errors
  KillOnTimeout = false
}

Nginx:

location ~ \.php$ {
    fastcgi_keep_conn on;

    fastcgi_buffers 8 16k;
    fastcgi_buffer_size 32k;
    fastcgi_read_timeout 900;
    fastcgi_send_timeout 900;
    fastcgi_intercept_errors off;

    fastcgi_pass   127.0.0.1:9000;

    fastcgi_index  index.php;
    fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
    include        fastcgi_params;
}

Answer 1

You need to enable the configuration hhvm.server.implicit_flush in your php.ini, then you can send a response body in case of fatal errors. To be able to catch fatal errors with an error handler, you should also enable hhvm.error_handling.call_user_handler_on_fatals.

For details, refer to the github issue on hhvm.

Answer 2

Use a custom error handler to handle any type of error exactly the way you want it to. Taken almost directly from example #1 in the link...

function myErrorHandler($errno, $errstr, $errfile, $errline)
{

    switch ($errno) {
    case E_USER_ERROR:
        echo "<b>My ERROR</b> [$errno] $errstr<br />\n";
        echo "  Fatal error on line $errline in file $errfile";
        echo ", PHP " . PHP_VERSION . " (" . PHP_OS . ")<br />\n";
        echo "Aborting...<br />\n";
        exit(1);
        break;

   case E_USER_WARNING:
        echo "<b>My WARNING</b> [$errno] $errstr<br />\n";
        break;

    case E_USER_NOTICE:
        echo "<b>My NOTICE</b> [$errno] $errstr<br />\n";
        break;

    default:
        echo "Unknown error type: [$errno] $errstr<br />\n";
        break;
    }

    /* Don't execute PHP internal error handler */
    return true;
}

set_error_handler("myErrorHandler");

For this approach to work, you have to set the error handler as early as possible in your code.

As you might have noticed I left one bit of code out, namely the one that checks if the error type is configured to be reported in your php/hhvm configuration. With the code above the errors will show regardless of your php/hhvm configuration. (so you probably want to log instead of echo errors in production environment hint)