/****************************************************************************
 *                                                                          *
 *                         GNAT COMPILER COMPONENTS                         *
 *                                                                          *
 *                              S E H - I N I T                             *
 *                                                                          *
 *                          C Implementation File                           *
 *                                                                          *
 *             Copyright (C) 2005, Free Software Foundation, Inc.           *
 *                                                                          *
 * GNAT is free software;  you can  redistribute it  and/or modify it under *
 * terms of the  GNU General Public License as published  by the Free Soft- *
 * ware  Foundation;  either version 2,  or (at your option) any later ver- *
 * sion.  GNAT is distributed in the hope that it will be useful, but WITH- *
 * OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY *
 * or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License *
 * for  more details.  You should have  received  a copy of the GNU General *
 * Public License  distributed with GNAT;  see file COPYING.  If not, write *
 * to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, *
 * Boston, MA 02110-1301, USA.                                              *
 *                                                                          *
 * As a  special  exception,  if you  link  this file  with other  files to *
 * produce an executable,  this file does not by itself cause the resulting *
 * executable to be covered by the GNU General Public License. This except- *
 * ion does not  however invalidate  any other reasons  why the  executable *
 * file might be covered by the  GNU Public License.                        *
 *                                                                          *
 * GNAT was originally developed  by the GNAT team at  New York University. *
 * Extensive contributions were provided by Ada Core Technologies Inc.      *
 *                                                                          *
 ****************************************************************************/

/*  This unit contains support for SEH (Structured Exception Handling).
    Right now the only implementation is for Win32.  */

#ifdef IN_RTS
#include "tconfig.h"
#include "tsystem.h"

/* We don't have libiberty, so us malloc.  */
#define xmalloc(S) malloc (S)

#else
#include "config.h"
#include "system.h"
#endif

#include "raise.h"

/* Addresses of exception data blocks for predefined exceptions. */
extern struct Exception_Data constraint_error;
extern struct Exception_Data numeric_error;
extern struct Exception_Data program_error;
extern struct Exception_Data storage_error;
extern struct Exception_Data tasking_error;
extern struct Exception_Data _abort_signal;

#define Raise_From_Signal_Handler \
                      ada__exceptions__raise_from_signal_handler
extern void Raise_From_Signal_Handler (struct Exception_Data *, const char *);


#ifdef _WIN32

#include <windows.h>
#include <excpt.h>

extern void _global_unwind2 (void *);

EXCEPTION_DISPOSITION __gnat_SEH_error_handler
(struct _EXCEPTION_RECORD*, void*, struct _CONTEXT*, void*);

EXCEPTION_DISPOSITION
__gnat_SEH_error_handler (struct _EXCEPTION_RECORD* ExceptionRecord,
			  void *EstablisherFrame,
			  struct _CONTEXT* ContextRecord ATTRIBUTE_UNUSED,
			  void *DispatcherContext ATTRIBUTE_UNUSED)
{
  struct Exception_Data *exception;
  const char *msg;

  switch (ExceptionRecord->ExceptionCode)
    {
    case EXCEPTION_ACCESS_VIOLATION:
      /* If the failing address isn't maximally-aligned or if the page
	 before the faulting page is not accessible, this is a program error.
      */
      if ((ExceptionRecord->ExceptionInformation[1] & 3) != 0
	  || IsBadCodePtr
	  ((void *)(ExceptionRecord->ExceptionInformation[1] + 4096)))
	{
	  exception = &program_error;
	  msg = "EXCEPTION_ACCESS_VIOLATION";
	}
      else
	{
	  /* otherwise it is a stack overflow  */
	  exception = &storage_error;
	  msg = "stack overflow (or erroneous memory access)";
	}
      break;

    case EXCEPTION_ARRAY_BOUNDS_EXCEEDED:
      exception = &constraint_error;
      msg = "EXCEPTION_ARRAY_BOUNDS_EXCEEDED";
      break;

    case EXCEPTION_DATATYPE_MISALIGNMENT:
      exception = &constraint_error;
      msg = "EXCEPTION_DATATYPE_MISALIGNMENT";
      break;

    case EXCEPTION_FLT_DENORMAL_OPERAND:
      exception = &constraint_error;
      msg = "EXCEPTION_FLT_DENORMAL_OPERAND";
      break;

    case EXCEPTION_FLT_DIVIDE_BY_ZERO:
      exception = &constraint_error;
      msg = "EXCEPTION_FLT_DENORMAL_OPERAND";
      break;

    case EXCEPTION_FLT_INVALID_OPERATION:
      exception = &constraint_error;
      msg = "EXCEPTION_FLT_INVALID_OPERATION";
      break;

    case EXCEPTION_FLT_OVERFLOW:
      exception = &constraint_error;
      msg = "EXCEPTION_FLT_OVERFLOW";
      break;

    case EXCEPTION_FLT_STACK_CHECK:
      exception = &program_error;
      msg = "EXCEPTION_FLT_STACK_CHECK";
      break;

    case EXCEPTION_FLT_UNDERFLOW:
      exception = &constraint_error;
      msg = "EXCEPTION_FLT_UNDERFLOW";
      break;

    case EXCEPTION_INT_DIVIDE_BY_ZERO:
      exception = &constraint_error;
      msg = "EXCEPTION_INT_DIVIDE_BY_ZERO";
      break;

    case EXCEPTION_INT_OVERFLOW:
      exception = &constraint_error;
      msg = "EXCEPTION_INT_OVERFLOW";
      break;

    case EXCEPTION_INVALID_DISPOSITION:
      exception = &program_error;
      msg = "EXCEPTION_INVALID_DISPOSITION";
      break;

    case EXCEPTION_NONCONTINUABLE_EXCEPTION:
      exception = &program_error;
      msg = "EXCEPTION_NONCONTINUABLE_EXCEPTION";
      break;

    case EXCEPTION_PRIV_INSTRUCTION:
      exception = &program_error;
      msg = "EXCEPTION_PRIV_INSTRUCTION";
      break;

    case EXCEPTION_SINGLE_STEP:
      exception = &program_error;
      msg = "EXCEPTION_SINGLE_STEP";
      break;

    case EXCEPTION_STACK_OVERFLOW:
      exception = &storage_error;
      msg = "EXCEPTION_STACK_OVERFLOW";
      break;

   default:
      exception = &program_error;
      msg = "unhandled signal";
    }

  /* This call is important as it avoids locking the second time we catch a
     signal. Note that this routine is documented as internal to Windows and
     should not be used.  */

  _global_unwind2 (EstablisherFrame);
  /* Call equivalent to RtlUnwind (EstablisherFrame, NULL, NULL, 0); */

  Raise_From_Signal_Handler (exception, msg);
  return 0; /* This is never reached, avoid compiler warning  */
}

/*  Install the Win32 SEH exception handler. Note that the caller must have
    allocated 8 bytes on the stack and pass the pointer to this stack
    space. This is needed as the SEH exception handler must be on the stack of
    the thread.

       int buf[2];

       __gnat_install_SEH_handler ((void*)buf);

       main();

   This call must be done before calling the main procedure or the thread
   entry. The stack space must exists during all the main run.  */

void
__gnat_install_SEH_handler (void *ER)
{
  int *ptr;

  /* put current handler in ptr */

  asm ("mov %%fs:(0),%%ecx" : : : "%ecx");
  asm ("mov %%ecx,%0" : "=m" (ptr));

  ((int *)ER)[0] = (int)ptr;                       /* previous handler */
  ((int *)ER)[1] = (int)__gnat_SEH_error_handler;  /* new handler */

  /* ptr is the new handler, set fs:(0) with this value */

  ptr = (int *)ER;
  asm ("mov %0,%%ecx" : : "m" (ptr) : "%ecx");
  asm ("mov %ecx,%fs:(0)");
}

#else /* _WIN32 */
/* For all non Windows targets we provide a dummy SEH install handler.  */
void __gnat_install_SEH_handler (void *eh ATTRIBUTE_UNUSED)
{
}
#endif