vdm.c

一个类似windows

/* $Id: vdm.c 21252 2006-03-08 20:03:59Z audit $
 *
 * COPYRIGHT:       See COPYING in the top level directory
 * PROJECT:         ReactOS kernel
 * FILE:            ntoskrnl/ke/i386/vdm.c
 * PURPOSE:         Virtual DOS machine support
 *
 * PROGRAMMERS:     David Welch ([e-mail])
 */

/* INCLUDES *****************************************************************/

#include <ntoskrnl.h>
#include <internal/debug.h>

#if defined (ALLOC_PRAGMA)
#pragma alloc_text(INIT, NtEarlyInitVdm)
#endif


/* GLOBALS *******************************************************************/

static UCHAR OrigIVT[1024];
static UCHAR OrigBDA[256];
/* static UCHAR OrigEBDA[]; */

extern VOID Ki386RetToV86Mode(PKV86M_REGISTERS InRegs,
			      PKV86M_REGISTERS OutRegs);

/* FUNCTIONS *****************************************************************/

VOID INIT_FUNCTION
NtEarlyInitVdm(VOID)
{
  /* GCC 3.4 warns if NULL is passed in parameter 2 to the standard function memcpy */
  PVOID start = (PVOID)0x0;

  /*
   * Save various BIOS data tables. At this point the lower 4MB memory
   * map is still active so we can just copy the data from low memory.
   */
  memcpy(OrigIVT, start, 1024);
  memcpy(OrigBDA, (PVOID)0x400, 256);
}

/*
 * @implemented
 */
NTSTATUS STDCALL NtVdmControl(ULONG ControlCode,
			      PVOID ControlData)
{
  KPROCESSOR_MODE PreviousMode;
  NTSTATUS Status = STATUS_SUCCESS;
  
  PreviousMode = ExGetPreviousMode();
  
  if (PreviousMode != KernelMode)
  {
    _SEH_TRY
    {
      switch (ControlCode)
      {
        case 0:
          ProbeForWrite(ControlData,
                        1024,
                        1);
          memcpy(ControlData, OrigIVT, 1024);
          break;

        case 1:
          ProbeForWrite(ControlData,
                        256,
                        1);
          memcpy(ControlData, OrigBDA, 256);
          break;

        case 2:
        {
          KV86M_REGISTERS V86Registers;
          
          ProbeForWrite(ControlData,
                        sizeof(KV86M_REGISTERS),
                        1);
          memcpy(&V86Registers,
                 ControlData,
                 sizeof(KV86M_REGISTERS));

          /* FIXME: This should use ->VdmObjects */
          KeGetCurrentProcess()->Unused = 1;
          Ki386RetToV86Mode(&V86Registers, &V86Registers);

          /* FIXME: This should use ->VdmObjects */
          KeGetCurrentProcess()->Unused = 0;
          
          memcpy(ControlData,
                 &V86Registers,
                 sizeof(KV86M_REGISTERS));
          break;
        }
      }
    }
    _SEH_HANDLE
    {
      Status = _SEH_GetExceptionCode();
    }
    _SEH_END;
  }
  
  return Status;
}

/* EOF */