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

   1 /* $Id$
   2 */
   3 /*
   4 */
   5
   6 #include <string.h>
   7
   8 #define NTOS_MODE_USER
   9 #include <ntos.h>
  10
  11 #include <napi/i386/segment.h>
  12 #include <napi/i386/floatsave.h>
  13
  14 #include <rosrtl/thread.h>
  15
  16 NTSTATUS NTAPI
  17 RtlRosInitializeContext
  18 (
  19  IN HANDLE ProcessHandle,
  20  OUT PCONTEXT Context,
  21  IN PVOID StartAddress,
  22  IN PINITIAL_TEB InitialTeb,
  23  IN ULONG ParameterCount,
  24  IN ULONG_PTR * Parameters
  25 )
  26 {
  27  static PVOID s_pRetAddr = (PVOID)0xDEADBEEF;
  28
  29  ULONG nDummy;
  30  SIZE_T nParamsSize = ParameterCount * sizeof(ULONG_PTR);
  31  NTSTATUS nErrCode;
  32  PVOID pStackBase;
  33  PVOID pStackLimit;
  34
  35  /* Intel x86: linear top-down stack, all parameters passed on the stack */
  36  /* get the stack base and limit */
  37  nErrCode = RtlpRosGetStackLimits(InitialTeb, &pStackBase, &pStackLimit);
  38
  39  /* failure */
  40  if(!NT_SUCCESS(nErrCode)) return nErrCode;
  41
  42  /* validate the stack */
  43  nErrCode = RtlpRosValidateTopDownUserStack(pStackBase, pStackLimit);
  44
  45  /* failure */
  46  if(!NT_SUCCESS(nErrCode)) return nErrCode;
  47
  48  /* too many parameters */
  49  if((nParamsSize + sizeof(ULONG_PTR)) > (SIZE_T)(pStackBase - pStackLimit))
  50   return STATUS_STACK_OVERFLOW;
  51
  52  memset(Context, 0, sizeof(CONTEXT));
  53
  54  /* initialize the context */
  55  Context->ContextFlags = CONTEXT_FULL;
  56  Context->FloatSave.ControlWord = FLOAT_SAVE_CONTROL;
  57  Context->FloatSave.StatusWord = FLOAT_SAVE_STATUS;
  58  Context->FloatSave.TagWord = FLOAT_SAVE_TAG;
  59  Context->FloatSave.DataSelector = FLOAT_SAVE_DATA;
  60  Context->Eip = (ULONG_PTR)StartAddress;
  61  Context->SegGs = USER_DS;
  62  Context->SegFs = TEB_SELECTOR;
  63  Context->SegEs = USER_DS;
  64  Context->SegDs = USER_DS;
  65  Context->SegCs = USER_CS;
  66  Context->SegSs = USER_DS;
  67  Context->Esp = (ULONG_PTR)pStackBase - (nParamsSize + sizeof(ULONG_PTR));
  68  Context->EFlags = ((ULONG_PTR)1 << 1) | ((ULONG_PTR)1 << 9);
  69
  70  /* write the parameters */
  71  nErrCode = NtWriteVirtualMemory
  72  (
  73   ProcessHandle,
  74   ((PUCHAR)pStackBase) - nParamsSize,
  75   Parameters,
  76   nParamsSize,
  77   &nDummy
  78  );
  79
  80  /* failure */
  81  if(!NT_SUCCESS(nErrCode)) return nErrCode;
  82
  83  /* write the return address */
  84  return NtWriteVirtualMemory
  85  (
  86   ProcessHandle,
  87   ((PUCHAR)pStackBase) - (nParamsSize + sizeof(ULONG_PTR)),
  88   &s_pRetAddr,
  89   sizeof(s_pRetAddr),
  90   &nDummy
  91  );
  92 }
  93
  94 /* EOF */