reactos/lib/rosrtl/thread/i386/context.c

   1 /* $Id$
   2 */
   3 /*
   4 */
   5
   6 #include <windows.h>
   7 #define NTOS_MODE_USER
   8 #include <ndk/ntndk.h>
   9
  10 #include <rosrtl/thread.h>
  11 #include <debug.h>
  12
  13 NTSTATUS NTAPI
  14 RtlRosInitializeContext
  15 (
  16  IN HANDLE ProcessHandle,
  17  OUT PCONTEXT Context,
  18  IN PVOID StartAddress,
  19  IN PINITIAL_TEB InitialTeb,
  20  IN ULONG ParameterCount,
  21  IN ULONG_PTR * Parameters
  22 )
  23 {
  24  static PVOID s_pRetAddr = (PVOID)0xDEADBEEF;
  25
  26  ULONG nDummy;
  27  SIZE_T nParamsSize = ParameterCount * sizeof(ULONG_PTR);
  28  NTSTATUS nErrCode;
  29  PVOID pStackBase;
  30  PVOID pStackLimit;
  31
  32  /* Intel x86: linear top-down stack, all parameters passed on the stack */
  33  /* get the stack base and limit */
  34  nErrCode = RtlpRosGetStackLimits(InitialTeb, &pStackBase, &pStackLimit);
  35
  36  /* failure */
  37  if(!NT_SUCCESS(nErrCode)) return nErrCode;
  38
  39  /* validate the stack */
  40  nErrCode = RtlpRosValidateTopDownUserStack(pStackBase, pStackLimit);
  41
  42  /* failure */
  43  if(!NT_SUCCESS(nErrCode)) return nErrCode;
  44
  45  /* too many parameters */
  46  if((nParamsSize + sizeof(ULONG_PTR)) > (SIZE_T)((ULONG_PTR)pStackBase - (ULONG_PTR)pStackLimit))
  47   return STATUS_STACK_OVERFLOW;
  48
  49  memset(Context, 0, sizeof(CONTEXT));
  50
  51  /* initialize the context */
  52  Context->ContextFlags = CONTEXT_FULL;
  53  Context->FloatSave.ControlWord = FLOAT_SAVE_CONTROL;
  54  Context->FloatSave.StatusWord = FLOAT_SAVE_STATUS;
  55  Context->FloatSave.TagWord = FLOAT_SAVE_TAG;
  56  Context->FloatSave.DataSelector = FLOAT_SAVE_DATA;
  57  Context->Eip = (ULONG_PTR)StartAddress;
  58  Context->SegGs = USER_DS;
  59  Context->SegFs = TEB_SELECTOR;
  60  Context->SegEs = USER_DS;
  61  Context->SegDs = USER_DS;
  62  Context->SegCs = USER_CS;
  63  Context->SegSs = USER_DS;
  64  Context->Esp = (ULONG_PTR)pStackBase - (nParamsSize + sizeof(ULONG_PTR));
  65  Context->EFlags = ((ULONG_PTR)1 << 1) | ((ULONG_PTR)1 << 9);
  66
  67  /* write the parameters */
  68  nErrCode = NtWriteVirtualMemory
  69  (
  70   ProcessHandle,
  71   ((PUCHAR)pStackBase) - nParamsSize,
  72   Parameters,
  73   nParamsSize,
  74   &nDummy
  75  );
  76
  77  /* failure */
  78  if(!NT_SUCCESS(nErrCode)) return nErrCode;
  79
  80  /* write the return address */
  81  return NtWriteVirtualMemory
  82  (
  83   ProcessHandle,
  84   ((PUCHAR)pStackBase) - (nParamsSize + sizeof(ULONG_PTR)),
  85   &s_pRetAddr,
  86   sizeof(s_pRetAddr),
  87   &nDummy
  88  );
  89 }
  90
  91 /* EOF */