/* The C++ exceptions runtime support

 *

 * Copyright 2002-2005 ARM Limited. All rights reserved.

 *

 * Your rights to use this code are set out in the accompanying licence

 * text file LICENCE.txt (ARM contract number LEC-ELA-00080 v1.0).

 */

/*

 * RCS $Revision: 92950 $

 * Checkin $Date: 2005-10-12 11:08:47 +0100 (Wed, 12 Oct 2005) $

 * Revising $Author: achapman $

 */

/* This source file is compiled automatically by ARM's make system into

 * multiple object files. The source regions constituting object file

 * xxx.o are delimited by ifdef xxx_c / endif directives.

 *

 * The source regions currently marked are:

 * arm_exceptions_globs_c

 * arm_exceptions_mem_c

 * arm_exceptions_uncaught_c

 * arm_exceptions_terminate_c

 * arm_exceptions_setterminate_c

 * arm_exceptions_unexpected_c

 * arm_exceptions_setunexpected_c

 * arm_exceptions_support_c

 * arm_exceptions_callterm_c

 * arm_exceptions_callunex_c

 * arm_exceptions_currenttype_c

 * arm_exceptions_alloc_c

 * arm_exceptions_free_c

 * arm_exceptions_throw_c

 * arm_exceptions_rethrow_c

 * arm_exceptions_foreign_c

 * arm_exceptions_cleanup_c

 * arm_exceptions_getexceptionptr_c

 * arm_exceptions_begincatch_c

 * arm_exceptions_endcatch_c

 * arm_exceptions_bad_typeid_c

 * arm_exceptions_bad_cast_c

 */

#include <string.h>

// Environment:

#include "unwind_env.h"

// Language-independent unwinder declarations:

#include "unwinder.h"

#ifdef __EPOC32__

/* Symbian specific support */

#include "symbian_support.h"

#endif

#include <new>

/* Barrier cache: */

/* Requirement imposed by C++ semantics module - pointer to match object in slot 0: */

#define BARRIER_HANDLEROBJECT (0)

/* Requirement imposed by C++ semantics module - function exception spec info */

#define BARRIER_FNSPECCOUNT  (1)

#define BARRIER_FNSPECBASE   (2)

#define BARRIER_FNSPECSTRIDE (3)

#define BARRIER_FNSPECARRAY  (4)

/* By default, none of these routines are unwindable: */

#pragma noexceptions_unwind

/* For brevity: */

typedef _Unwind_Control_Block UCB;

using std::terminate_handler;

using std::unexpected_handler;

using std::terminate;

using std::unexpected;

using std::type_info;

/* Redeclare these interface routines as weak, so using them does not

 * pull in the unwind library. We only want the unwind library if

 * someone throws (or raises an exception from some other language).

 */

WEAKDECL NORETURNDECL void _Unwind_Resume(UCB *);

WEAKDECL void _Unwind_Complete(UCB *);

/* Diagnostics:

 * Define DEBUG to get extra interfaces which assist debugging this functionality.

 * Define CPP_DIAGNOSTICS for printed diagnostics.

 */

#ifdef DEBUG

#define CPP_DIAGNOSTICS

#endif

#ifdef CPP_DIAGNOSTICS

#ifndef __EPOC32__

extern "C" int printf(const char *, ...);

#endif

#endif

/* --------- "Exceptions_class" string for our implementation: --------- */

#define EXCEPTIONS_CLASS_SIZE 8

#define ARMCPP_EXCEPTIONS_CLASS "ARM\0C++\0"

/* --------- Exception control object: --------- */

// Type __cxa_exception is the combined C++ housekeeping (LEO) and UCB.

// It will be followed by the user exception object, hence must ensure

// the latter is aligned on an 8 byte boundary.

#ifndef __EPOC32__

struct __cxa_exception {

  const type_info *exceptionType;       // RTTI object describing the type of the exception

  void *(*exceptionDestructor)(void *); // Destructor for the exception object (may be NULL)

  unexpected_handler unexpectedHandler; // Handler in force after evaluating throw expr

  terminate_handler terminateHandler;   // Handler in force after evaluating throw expr

  __cxa_exception *nextCaughtException; // Chain of "currently caught" c++ exception objects

  uint32_t handlerCount;                // Count of how many handlers this EO is "caught" in

  __cxa_exception *nextPropagatingException; // Chain of objects saved over cleanup

  uint32_t propagationCount;            // Count of live propagations (throws) of this EO

  UCB ucb;                              // Forces alignment of next item to 8-byte boundary

};

#endif

/* --------- Control "globals": --------- */

// We do this by putting all the thread-specific "globals" into a single

// area of store, which we allocate space for dynamically.

// We don't define a constructor for this; see comments with __cxa_get_globals.

#ifndef __EPOC32__

typedef void (*handler)(void);

struct __cxa_eh_globals {

  uint32_t uncaughtExceptions;               // counter

  unexpected_handler unexpectedHandler;      // per-thread handler

  terminate_handler terminateHandler;        // per-thread handler

  bool implementation_ever_called_terminate; // true if it ever did

  handler call_hook;     // transient field to tell terminate/unexpected which hook to call

  __cxa_exception *caughtExceptions;         // chain of "caught" exceptions

  __cxa_exception *propagatingExceptions;    // chain of "propagating" (in cleanup) exceptions

  void *emergency_buffer;                    // emergency buffer for when rest of heap full

};

#endif

/* ---------- Entry points: ---------- */

/* There is a little type-delicacy required here as __cxa_throw takes a

 * function pointer. Setting aside the problem of not being able to form

 * a pointer to a destructor in C++, if we simply say extern "C" here

 * then the function pointer will also have C linkage and will be a

 * pointer to a C function. This causes problems when __cxa_throw is

 * defined (unless we repeat the extern "C" at the definition site) because

 * the fnptr in the definition gets C++ linkage, hence that __cxa_throw has

 * a different signature to the declared one, and so the function we wanted

 * doesn't get defined at all.

 * Maybe it should just take a void * but this seems more honest.

 */

typedef void *(*cppdtorptr)(void *);

extern "C" {

  // Protocol routines called directly from application code

  IMPORT_C void *__cxa_allocate_exception(size_t size);

  IMPORT_C void __cxa_free_exception(void *);

  WEAKDECL void __cxa_throw(void *, const type_info *, cppdtorptr);

  IMPORT_C void __cxa_rethrow(void);

  IMPORT_C void *__cxa_get_exception_ptr(UCB *);

  void *__cxa_begin_catch(UCB *);

  IMPORT_C void __cxa_end_catch(void);

  IMPORT_C void __cxa_end_cleanup(void);

  IMPORT_C const type_info *__cxa_current_exception_type(void);

  // Protocol routines usually called only by the personality routine(s).

  IMPORT_C void __cxa_call_terminate(UCB *);

  IMPORT_C void __cxa_call_unexpected(UCB *);

  IMPORT_C bool __cxa_begin_cleanup(UCB *);

  typedef enum {

    ctm_failed = 0,

    ctm_succeeded = 1,

    ctm_succeeded_with_ptr_to_base = 2

  } __cxa_type_match_result;

  IMPORT_C __cxa_type_match_result __cxa_type_match(UCB *, const std::type_info *,

                                                    bool is_reference_type, void **);

  // Auxilliary routines

  __cxa_eh_globals *__cxa_get_globals(void);

  IMPORT_C void __cxa_bad_typeid(void);

  IMPORT_C void __cxa_bad_cast(void);

  // Emergency memory buffer management routines

  void *__ARM_exceptions_buffer_init(void);

  void *__ARM_exceptions_buffer_allocate(void *, size_t);

  void *__ARM_exceptions_buffer_free(void *, void *);

}

// Support routines

#define NAMES __ARM

namespace NAMES {

  void default_unexpected_handler(void);

  void call_terminate_handler(UCB *);

  void eh_catch_semantics(UCB *);

  bool is_foreign_exception(UCB *);

  bool same_exceptions_class(const void *, const void *);

  __cxa_exception *get_foreign_intermediary(__cxa_exception *, UCB *);

}

// Macro: convert ucb pointer to __cxa_exception pointer

#define ucbp_to_ep(UCB_P) ((__cxa_exception *)((char *)(UCB_P) - offsetof(__cxa_exception, ucb)))

#ifdef arm_exceptions_globs_c

/* --------- Allocating and retrieving "globals": --------- */

// The exception-handling globals should be allocated per-thread.

// This is done here assuming the existance of a zero-initialised void*

// pointer location obtainable by the macro EH_GLOBALS.

// Default terminate handler:

#ifndef __EPOC32__

static void __default_terminate_handler(void) {

  abort();

}

#endif

// If std::unexpected() is in the image, include a default handler for it:

namespace NAMES { WEAKDECL void default_unexpected_handler(void); }

// ARM's toolchain documentation states that if symbol

// __ARM_exceptions_buffer_required is present we should allocate

// an emergency buffer.

// As we aren't allowed static data in ARM library builds, reference the

// symbol by declaring it a function. This causes an additional problem when

// ARM libraries are built position-independent, namely that an absent

// function doesn't compare address-equal to NULL. So we have to get the

// "addresses" from two different compilation units and compare those.

// This is a known defect, to be fixed in the compiler.

extern "C" WEAKDECL void __ARM_exceptions_buffer_required(void);

extern void (*(__ARM_exceptions_buffer_required_address(void)))(void);

// The address comparison function only needs to be used when we are building 

// position-independent.  In other cases, comparing the address to NULL is more

// efficient.

#if 0

#  define ARM_EXCEPTIONS_BUFFER_NOT_REQUIRED() (&__ARM_exceptions_buffer_required != __ARM_exceptions_buffer_required_address())

#else

#  define ARM_EXCEPTIONS_BUFFER_NOT_REQUIRED() (&__ARM_exceptions_buffer_required == NULL)

#endif

// __cxa_eh_globals returns the per-thread memory. There are several complications,

// all of which relate to not touching the exceptions system while trying to

// initialise it:

// 1) We can't obtain memory by calling new or nothrow new as both of these use

//    exceptions internally, so we must use malloc

// 2) We choose not to initialise the memory via placement new and a constructor,

//    since placement new is declared with an empty function exception specification,

//    which causes more of the exceptions system to always be pulled in.

// 3) We can't call terminate, as terminate looks in the memory we are trying to

//    allocate.

EXPORT_C __cxa_eh_globals *__cxa_get_globals(void)

{

  __cxa_eh_globals *this_thread_globals = (__cxa_eh_globals *)(EH_GLOBALS);

#ifndef __EPOC32__

  /* The Symbian implementation allocates the required space on the threads stack

     at thread creation and sets up thread local storage to point to the globals

     which are also initialised

  */

  if (this_thread_globals == NULL) {

    // First call

    // Obtain some memory: this is thread-safe provided malloc is.

    this_thread_globals = (__cxa_eh_globals *)malloc(sizeof(__cxa_eh_globals));

    if (this_thread_globals == NULL) abort(); // NOT terminate(), which calls this fn

    // Save the pointer in the specially-provided location

    EH_GLOBALS = this_thread_globals;

    // Finally initialise the memory by hand

    this_thread_globals->uncaughtExceptions = 0;

    this_thread_globals->unexpectedHandler = NAMES::default_unexpected_handler;

    this_thread_globals->terminateHandler = __default_terminate_handler;

    this_thread_globals->implementation_ever_called_terminate = false;

    this_thread_globals->call_hook = NULL;

    this_thread_globals->caughtExceptions = NULL;

    this_thread_globals->propagatingExceptions = NULL;

    if (ARM_EXCEPTIONS_BUFFER_NOT_REQUIRED())

      this_thread_globals->emergency_buffer = NULL;

    else

      this_thread_globals->emergency_buffer = __ARM_exceptions_buffer_init();

  }

#endif

  return this_thread_globals;

}

#endif /* arm_exceptions_globs_c */

#ifdef arm_exceptions_mem_c

/* --------- Emergency memory: --------- */

// It is possible to reserve memory for throwing bad_alloc when the heap

// is otherwise full. The ARM implementation provides hooks to do this.

// The default implementation reserves just enough space for a bad_alloc

// object, so if memory is later exhausted bad_alloc can still be thrown.

// Note there is no guarantee or requirement that the exception being

// thrown is actually bad_alloc.

// A usage flag and enough space for a bad_alloc exception control object

#ifndef __EPOC32__

struct emergency_eco {

  __cxa_exception ep;

  std::bad_alloc b;

};

struct emergency_buffer {

  bool inuse;

  struct emergency_eco eco;

};

#endif

#ifndef __EPOC32__

// The SymbianOS implementation allocates this space at thread creation

// Initialiser

void* __ARM_exceptions_buffer_init(void)

{

  emergency_buffer *buffer = (emergency_buffer *)malloc(sizeof(emergency_buffer));

  if (buffer == NULL) return NULL;

  buffer->inuse = false;

  return buffer;

}

#endif

// Allocator

void *__ARM_exceptions_buffer_allocate(void *buffer, size_t size)

{

  emergency_buffer *b = (emergency_buffer *)buffer;

  if (size > sizeof(emergency_eco) || b == NULL || b->inuse) return NULL;

  b->inuse = true;

  return &b->eco;

}

// Deallocator: Must return non-NULL if and only if it recognises

// and releases the supplied object

void *__ARM_exceptions_buffer_free(void *buffer, void *addr)

{

  emergency_buffer *b = (emergency_buffer *)buffer;

  if (b == NULL || addr != &b->eco) return NULL;

  b->inuse = false;

  return b;

}

#  if 0

// Hook activation support - see comments earlier

extern "C" WEAKDECL void __ARM_exceptions_buffer_required(void);

void (*(__ARM_exceptions_buffer_required_address(void)))(void)

{

  return &__ARM_exceptions_buffer_required;

}

#  endif

#endif /* arm_exceptions_mem_c */

#ifdef arm_exceptions_uncaught_c

/* ---- uncaught_exception() ---- */

/* The EDG (and I think our) interpretation is that if the implementation

 * ever called terminate(), uncaught_exception() should return true.

 */

#if __ARMCC_VERSION < 220000

bool std::uncaught_exception(void)

#else

EXPORT_C bool std::uncaught_exception(void)

#endif

{

   __cxa_eh_globals *g = __cxa_get_globals();

   return g->implementation_ever_called_terminate || g->uncaughtExceptions;

}

#endif /* arm_exceptions_uncaught_c */

#ifdef arm_exceptions_terminate_c

/* ---- terminate() etc ---- */

/* The behaviour of terminate() must differ between calls by the

 * implementation and calls by the application. This is achieved by having the

 * implementation set call_hook immediately before the call to terminate().

 * The hook called by terminate() should terminate the program without

 * returning to the caller. There is no requirement for terminate() itself to

 * intercept throws.

 */

EXPORT_C void std::terminate(void)

{

  __cxa_eh_globals *g = __cxa_get_globals();

  if (g->call_hook != NULL) {

    // Clear then call hook fn we were passed

    handler call_hook = g->call_hook;

    g->call_hook = NULL;

    call_hook();

  } else {

    // Call global hook fn

    g->terminateHandler();

  }

  // If hook fn returns:

  abort();

}

#endif /* arm_exceptions_terminate_c */

#ifdef arm_exceptions_setterminate_c

EXPORT_C terminate_handler std::set_terminate(terminate_handler h) throw()

{

  __cxa_eh_globals *g = __cxa_get_globals();

  terminate_handler old = g->terminateHandler;

  g->terminateHandler = h;

  return old;

}

#endif /* arm_exceptions_setterminate_c */

#ifdef arm_exceptions_unexpected_c

/* ---- unexpected() etc ---- */

/* Comments as per terminate() */

void NAMES::default_unexpected_handler(void) {

  terminate();

}

#pragma exceptions_unwind

EXPORT_C void std::unexpected(void)

{

  __cxa_eh_globals *g = __cxa_get_globals();

  if (g->call_hook != NULL) {

    // Clear then call hook fn we were passed

    handler call_hook = g->call_hook;

    g->call_hook = NULL;

    call_hook();

  } else {

    // Call global hook fn

    g->unexpectedHandler();

  }

  // If hook fn returns:

  abort();

}

#endif /* arm_exceptions_unexpected_c */

#ifdef arm_exceptions_setunexpected_c

EXPORT_C unexpected_handler std::set_unexpected(unexpected_handler h) throw()

{

  __cxa_eh_globals *g = __cxa_get_globals();

  unexpected_handler old = g->unexpectedHandler;

  g->unexpectedHandler = h;

  return old;

}

#endif /* arm_exceptions_setunexpected_c */

#ifdef arm_exceptions_support_c

/* ---------- Helper functions: ---------- */