hphp/runtime/vm/unwind.h

   1 /*
   2    +----------------------------------------------------------------------+
   3    | HipHop for PHP                                                       |
   4    +----------------------------------------------------------------------+
   5    | Copyright (c) 2010-2014 Facebook, Inc. (http://www.facebook.com)     |
   6    +----------------------------------------------------------------------+
   7    | This source file is subject to version 3.01 of the PHP license,      |
   8    | that is bundled with this package in the file LICENSE, and is        |
   9    | available through the world-wide-web at the following url:           |
  10    | http://www.php.net/license/3_01.txt                                  |
  11    | If you did not receive a copy of the PHP license and are unable to   |
  12    | obtain it through the world-wide-web, please send a note to          |
  13    | license@php.net so we can mail you a copy immediately.               |
  14    +----------------------------------------------------------------------+
  15 */
  16 #ifndef incl_HPHP_UNWIND_H_
  17 #define incl_HPHP_UNWIND_H_
  18
  19 #include <stdexcept>
  20
  21 namespace HPHP {
  22
  23 //////////////////////////////////////////////////////////////////////
  24
  25 /*
  26  * Enumerates actions that should be taken by the enterVM loop after
  27  * unwinding an exception.
  28  */
  29 enum class UnwindAction {
  30   /*
  31    * The exception was not handled in this nesting of the VM---it
  32    * needs to be rethrown.
  33    */
  34   Propagate,
  35
  36   /*
  37    * A catch or fault handler was identified and the VM state has been
  38    * prepared for entry to it.
  39    */
  40   ResumeVM,
  41 };
  42
  43 /*
  44  * The main entry point to the unwinder.
  45  *
  46  * When an exception propagates up to the top-level try/catch in
  47  * enterVM, it calls to this module to perform stack unwinding as
  48  * appropriate.  This function must be called from within the catch
  49  * handler (it rethrows the exception to determine what to do).
  50  *
  51  * The returned UnwindAction instructs enterVM on how to proceed.
  52  */
  53 UnwindAction exception_handler() noexcept;
  54
  55 //////////////////////////////////////////////////////////////////////
  56
  57 /*
  58  * This exception is thrown when executing an Unwind bytecode, which
  59  * will reraise the current fault and resume propagating it.
  60  */
  61 struct VMPrepareUnwind : std::exception {
  62   const char* what() const throw() { return "VMPrepareUnwind"; }
  63 };
  64
  65 /*
  66  * Thrown when we need to "switch modes" by re-starting the current VM
  67  * invocation.  For example, if we need to break for the debugger, or
  68  * enable code coverage mode.
  69  */
  70 struct VMSwitchMode : std::exception {
  71   const char* what() const throw() { return "VMSwitchMode"; }
  72 };
  73
  74 /*
  75  * Thrown for stack overflow thrown from a prolog while
  76  * re-entering
  77  */
  78 struct VMReenterStackOverflow : std::exception {
  79   const char* what() const throw() { return "VMReenterStackOverflow"; }
  80 };
  81
  82 /*
  83  * Same as VMSwitchMode, except for use from a builtin---the frame for
  84  * the builtin function should be unwound before resuming the VM.
  85  */
  86 struct VMSwitchModeBuiltin : std::exception {
  87   const char* what() const throw() { return "VMSwitchModeBuiltin"; }
  88 };
  89
  90 //////////////////////////////////////////////////////////////////////
  91
  92 }
  93
  94 #endif