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

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