1. /*++
  3. Copyright (c) 1989-2001 Microsoft Corporation
  5. Module Name:
  7. systime.c
  9. Abstract:
  11. This module implements the NT system time services.
  13. --*/
  15. #include "exp.h"
  17. //
  18. // Guards against multiple threads attempting to set the system time.
  19. //
  20. INITIALIZED_CRITICAL_SECTION(ExpTimeRefreshLock);
  22. NTSTATUS
  23. NtSetSystemTime (
  24. IN PLARGE_INTEGER SystemTime,
  25. OUT PLARGE_INTEGER PreviousTime OPTIONAL
  26. )
  28. /*++
  30. Routine Description:
  32. This function sets the current system time and optionally returns the
  33. previous system time.
  35. Arguments:
  37. SystemTime - Supplies a pointer to the new value for the system time.
  39. PreviousTime - Supplies an optional pointer to a variable that receives
  40. the previous system time.
  42. Return Value:
  44. STATUS_SUCCESS is returned if the service is successfully executed.
  46. STATUS_ACCESS_VIOLATION is returned if the input parameter for the
  47. system time cannot be read or the output parameter for the system
  48. time cannot be written.
  50. STATUS_INVALID_PARAMETER is returned if the input system time is negative.
  52. --*/
  54. {
  55. LARGE_INTEGER CurrentTime;
  56. LARGE_INTEGER NewTime;
  57. TIME_FIELDS TimeFields;
  59. PAGED_CODE();
  61. RtlEnterCriticalSectionAndRegion(&ExpTimeRefreshLock);
  63. //
  64. // Get the new system time and check to ensure that the value is
  65. // positive and resonable. If the new system time is negative, then
  66. // return an invalid parameter status.
  67. //
  69. NewTime = *SystemTime;
  71. if ((NewTime.HighPart < 0) || (NewTime.HighPart > 0x20000000)) {
  72. RtlLeaveCriticalSectionAndRegion(&ExpTimeRefreshLock);
  73. return STATUS_INVALID_PARAMETER;
  74. }
  76. //
  77. // Set the system time, and capture the previous system time in a
  78. // local variable, then store the local variable in the previous time
  79. // variable if it is specified. This is required so that faults can
  80. // be prevented from happening in the set time routine.
  81. //
  83. KeSetSystemTime(&NewTime, &CurrentTime);
  85. RtlTimeToTimeFields(&NewTime, &TimeFields);
  86. HalSetRealTimeClock(&TimeFields);
  88. if (ARGUMENT_PRESENT(PreviousTime)) {
  89. *PreviousTime = CurrentTime;
  90. }
  92. //
  93. // Mark the CMOS data as valid.
  94. //
  96. HalMarkCmosValid();
  98. RtlLeaveCriticalSectionAndRegion(&ExpTimeRefreshLock);
  99. return STATUS_SUCCESS;
  100. }

systime.h