windows-nt/Source/XPSP1/NT/admin/display/loghours/log_gmt.cpp
2020-09-26 16:20:57 +08:00

417 lines
9.4 KiB
C++

/*++
Copyright (c) 1987-2001 Microsoft Corporation
Module Name:
log_gmt.cpp (originally named loghours.c)
Abstract:
Private routines to support rotation of logon hours between local time
and GMT time.
Environment:
User mode only.
Contains NT-specific code.
Requires ANSI C extensions: slash-slash comments, long external names.
Revision History:
16-Mar-93 cliffv Creation.
22-Jul-97 t-danm Copied from /nt/private/nw/convert/nwconv/loghours.c
and adapted to loghours.dll.
--*/
//#include "stdafx.h"
#pragma warning (disable : 4514)
#pragma warning (push,3)
extern "C" {
#include <nt.h>
#include <ntrtl.h>
#include <nturtl.h>
#include <windef.h>
#include <winbase.h>
}
#include <limits.h>
#include <math.h>
#include <lmcons.h>
#include <lmaccess.h>
#pragma warning (pop)
#include "log_gmt.h"
//#pragma hdrstop
/*++
Routine NetpRotateLogonHoursPhase1()
Determine the amount to rotate the logon hours by to convert to/from GMT
Arguments:
ConvertToGmt -
True to convert the logon hours from local time to GMT relative
False to convert the logon hours from GMT relative to local time
RotateCount - Returns the number of bits to shift by.
Return Value:
TRUE if the RotateCount could be computed
FALSE if a RotateCount could not be computed
--*/
BOOLEAN
NetpRotateLogonHoursPhase1(
IN BOOL ConvertToGmt,
IN bool bAddDaylightBias,
OUT PLONG RotateCount)
{
TIME_ZONE_INFORMATION tzi;
LONG BiasInHours = 0;
LONG DSTBias = 0;
//
// Get the timezone data from the registry
//
DWORD dwResult = GetTimeZoneInformation( &tzi );
if ( TIME_ZONE_ID_INVALID == dwResult )
{
return FALSE;
}
//
// Compute the amount to rotate the logon hours by
//
// Round the bias in minutes to the closest bias in hours.
// Take into consideration that Bias can be negative.
// Do this by forcing the Bias to be positive, rounding,
// then adjusting it back negative again.
//
if ( bAddDaylightBias )
{
switch (dwResult)
{
case TIME_ZONE_ID_DAYLIGHT:
DSTBias = tzi.DaylightBias;
break;
case TIME_ZONE_ID_UNKNOWN:
case TIME_ZONE_ID_STANDARD:
DSTBias = tzi.StandardBias;
break;
default:
return FALSE;
}
}
ASSERT( tzi.Bias > -(24*60) );
BiasInHours = ((tzi.Bias + DSTBias + (24*60) + 30)/60) - 24;
if ( !ConvertToGmt )
{
BiasInHours = - BiasInHours;
}
*RotateCount = BiasInHours;
return TRUE;
} // NetpRotateLogonHoursPhase1()
/*++
Routine NetpRotateLogonHoursPhase2()
Rotate the LogonHours bit mask by the required amount.
Arguments:
LogonHours - Pointer to LogonHour bit mask
UnitsPerWeek - Number of bits in the bit mask. Must be UNITS_PER_WEEK (168).
RotateCount - Number of bits to rotate by. Must be between 31 and -31.
Negative means to rotate left.
Positive means to rotate right.
Return Value:
TRUE if the rotation succeeded.
FALSE if a parameter was out of range
--*/
BOOLEAN
NetpRotateLogonHoursPhase2(
IN PBYTE LogonHours,
IN DWORD UnitsPerWeek,
IN LONG RotateCount)
{
//
// Useful constants
//
const int DWORDS_PER_WEEK = ((UNITS_PER_WEEK+31)/32);
const int BYTES_PER_WEEK = (UNITS_PER_WEEK/8);
DWORD AlignedLogonHours[DWORDS_PER_WEEK+1];
::ZeroMemory (AlignedLogonHours, sizeof (DWORD) * (DWORDS_PER_WEEK+1));
LONG i = 0;
BOOLEAN RotateLeft = FALSE;
//
// Ensure there are 8 bits per byte,
// 32 bits per DWORD and
// units per week is even number of bytes.
//
#pragma warning(disable : 4127)
ASSERT( CHAR_BIT == 8 );
ASSERT( sizeof(DWORD) * CHAR_BIT == 32 );
ASSERT( UNITS_PER_WEEK/8*8 == UNITS_PER_WEEK );
#pragma warning (default : 4127)
//
// Validate the input parameters
//
if ( UnitsPerWeek != UNITS_PER_WEEK )
{
ASSERT( UnitsPerWeek == UNITS_PER_WEEK );
return FALSE;
}
if ( RotateCount == 0 )
{
return TRUE;
}
RotateLeft = (RotateCount < 0);
RotateCount = labs( RotateCount );
if ( RotateCount > 31 )
{
ASSERT ( RotateCount <= 31 );
return FALSE;
}
//
// Do the left rotate.
//
if (RotateLeft)
{
//
// Copy the logon hours to a DWORD aligned buffer.
//
// Duplicate the first dword at the end of the buffer to make
// the rotation code trivial.
//
RtlCopyMemory(AlignedLogonHours, LogonHours, BYTES_PER_WEEK );
RtlCopyMemory( ((PBYTE)AlignedLogonHours)+BYTES_PER_WEEK,
LogonHours,
sizeof(DWORD) );
//
// Actually rotate the data.
//
for ( i=0; i < DWORDS_PER_WEEK; i++ )
{
AlignedLogonHours[i] =
(AlignedLogonHours[i] >> RotateCount) |
(AlignedLogonHours[i+1] << (32-RotateCount));
}
//
// Copy the logon hours back to the input buffer.
//
RtlCopyMemory( LogonHours, AlignedLogonHours, BYTES_PER_WEEK );
//
// Do the right rotate.
//
}
else
{
//
// Copy the logon hours to a DWORD aligned buffer.
//
// Duplicate the last DWORD at the front of the buffer to make
// the rotation code trivial.
//
RtlCopyMemory( &AlignedLogonHours[1], LogonHours, BYTES_PER_WEEK );
RtlCopyMemory( AlignedLogonHours,
&LogonHours[BYTES_PER_WEEK-4],
sizeof(DWORD));
//
// Actually rotate the data.
//
for ( i=DWORDS_PER_WEEK-1; i>=0; i-- )
{
AlignedLogonHours[i+1] =
(AlignedLogonHours[i+1] << RotateCount) |
(AlignedLogonHours[i] >> (32-RotateCount));
}
//
// Copy the logon hours back to the input buffer.
//
RtlCopyMemory( LogonHours, &AlignedLogonHours[1], BYTES_PER_WEEK );
}
return TRUE;
} // NetpRotateLogonHoursPhase2()
/*++
Routine NetpRotateLogonHours()
Rotate the LogonHours bit mask to/from GMT relative time.
Arguments:
LogonHours - Pointer to LogonHour bit mask
UnitsPerWeek - Number of bits in the bit mask. Must be UNITS_PER_WEEK (168).
ConvertToGmt -
True to convert the logon hours from local time to GMT relative
False to convert the logon hours from GMT relative to local time
Return Value:
TRUE if the rotation succeeded.
FALSE if a parameter was out of range
--*/
BOOLEAN
NetpRotateLogonHours(
IN OUT PBYTE rgbLogonHours, // Array of 21 bytes
IN DWORD cbitUnitsPerWeek, // Must be 21 * 8 = 168
IN BOOL fConvertToGmt,
IN bool bAddDaylightBias)
{
LONG RotateCount = 0;
//
// Break the functionality into two phases so that if the caller is doing
// this multiple time, he just calls Phase 1 once and Phase 2 multiple
// times.
//
if ( !NetpRotateLogonHoursPhase1 (fConvertToGmt, bAddDaylightBias, &RotateCount) )
{
return FALSE;
}
return NetpRotateLogonHoursPhase2 (rgbLogonHours, cbitUnitsPerWeek, RotateCount );
} // NetpRotateLogonHours()
/*++
Routine NetpRotateLogonHoursBYTE()
Rotate the LogonHours BYTE array to/from GMT relative time.
Each BYTE is one hour. The contents of a BYTE must not change
Arguments:
LogonHours - Pointer to LogonHour bit mask
UnitsPerWeek - Number of BYTES in the BYTE array. Must be UNITS_PER_WEEK (168).
ConvertToGmt -
True to convert the logon hours from local time to GMT relative
False to convert the logon hours from GMT relative to local time
Return Value:
TRUE if the rotation succeeded.
FALSE if a parameter was out of range
--*/
BOOLEAN
NetpRotateLogonHoursBYTE(
IN OUT PBYTE rgbLogonHours, // Array of 168 bytes
IN DWORD cbitUnitsPerWeek, // Must be 21 * 8 = 168
IN BOOL fConvertToGmt,
IN bool bAddDaylightBias)
{
LONG RotateCount = 0;
//
// Break the functionality into two phases so that if the caller is doing
// this multiple time, he just calls Phase 1 once and Phase 2 multiple
// times.
//
if ( !NetpRotateLogonHoursPhase1 (fConvertToGmt, bAddDaylightBias, &RotateCount) )
{
return FALSE;
}
BOOLEAN bResult = TRUE;
ASSERT (RotateCount >= -12 && RotateCount <= 12);
if ( RotateCount != 0 )
{
size_t numBytes = abs (RotateCount);
PBYTE pTemp = new BYTE[cbitUnitsPerWeek + numBytes];
if ( pTemp )
{
if ( RotateCount < 0 ) // shift left
{
// Copy the entire array and then start over with numBytes BYTES from
// the start of the array to fill up to the end of the temp array.
// Then shift over numBytes BYTES and copy 168 bytes from the temp
// array back to the original array.
memcpy (pTemp, rgbLogonHours, cbitUnitsPerWeek);
memcpy (pTemp + cbitUnitsPerWeek, rgbLogonHours, numBytes);
memcpy (rgbLogonHours, pTemp + numBytes, cbitUnitsPerWeek);
}
else // RotateCount > 0 -- shift right
{
// Copy numBytes BYTES from the end of the array and then copy
// the entire array to fill up to the end of the temp array.
// The copy 168 bytes from the beginning of the temp array back
// to the original array.
memcpy (pTemp, rgbLogonHours + (cbitUnitsPerWeek - numBytes), numBytes);
memcpy (pTemp + numBytes, rgbLogonHours, cbitUnitsPerWeek);
memcpy (rgbLogonHours, pTemp, cbitUnitsPerWeek);
}
delete [] pTemp;
}
else
bResult = FALSE;
}
return bResult;
} // NetpRotateLogonHours()