Leaked source code of windows server 2003
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/*++
Copyright (c) 1993 Microsoft Corporation
Module Name:
checksum.c
Abstract:
This module implements a function for computing the checksum of an
image file. It will also compute the checksum of other files as well.
Author:
David N. Cutler (davec) 21-Mar-1993
Revision History:
--*/
#include <nt.h>
#include <ntrtl.h>
#include <nturtl.h>
#include <private.h>
//
// Define checksum routine prototype.
//
#ifdef __cplusplus
extern "C"
#endif
USHORT
ChkSum(
DWORD PartialSum,
PUSHORT Source,
DWORD Length
);
PIMAGE_NT_HEADERS
CheckSumMappedFile (
LPVOID BaseAddress,
DWORD FileLength,
LPDWORD HeaderSum,
LPDWORD CheckSum
)
/*++
Routine Description:
This functions computes the checksum of a mapped file.
Arguments:
BaseAddress - Supplies a pointer to the base of the mapped file.
FileLength - Supplies the length of the file in bytes.
HeaderSum - Suppllies a pointer to a variable that receives the checksum
from the image file, or zero if the file is not an image file.
CheckSum - Supplies a pointer to the variable that receive the computed
checksum.
Return Value:
None.
--*/
{
PUSHORT AdjustSum;
PIMAGE_NT_HEADERS NtHeaders;
USHORT PartialSum;
PBYTE pbyte;
//
// Compute the checksum of the file and zero the header checksum value.
//
*CheckSum = 0;
*HeaderSum = 0;
PartialSum = ChkSum(0, (PUSHORT)BaseAddress, FileLength >> 1);
//
// If the file is an image file, then subtract the two checksum words
// in the optional header from the computed checksum before adding
// the file length, and set the value of the header checksum.
//
__try {
NtHeaders = RtlpImageNtHeader(BaseAddress);
} __except(EXCEPTION_EXECUTE_HANDLER) {
NtHeaders = NULL;
}
if ((NtHeaders != NULL) && (NtHeaders != BaseAddress)) {
if (NtHeaders->OptionalHeader.Magic == IMAGE_NT_OPTIONAL_HDR32_MAGIC) {
*HeaderSum = ((PIMAGE_NT_HEADERS32)NtHeaders)->OptionalHeader.CheckSum;
AdjustSum = (PUSHORT)(&((PIMAGE_NT_HEADERS32)NtHeaders)->OptionalHeader.CheckSum);
} else
if (NtHeaders->OptionalHeader.Magic == IMAGE_NT_OPTIONAL_HDR64_MAGIC) {
*HeaderSum = ((PIMAGE_NT_HEADERS64)NtHeaders)->OptionalHeader.CheckSum;
AdjustSum = (PUSHORT)(&((PIMAGE_NT_HEADERS64)NtHeaders)->OptionalHeader.CheckSum);
} else {
return(NULL);
}
PartialSum -= (PartialSum < AdjustSum[0]);
PartialSum -= AdjustSum[0];
PartialSum -= (PartialSum < AdjustSum[1]);
PartialSum -= AdjustSum[1];
}
// add the last byte, if needed
if (FileLength % 2) {
pbyte = (PBYTE)BaseAddress + FileLength - 1;
PartialSum += *pbyte;
PartialSum = (PartialSum >> 16) + (PartialSum & 0xFFFF);
}
//
// Compute the final checksum value as the sum of the paritial checksum
// and the file length.
//
*CheckSum = (DWORD)PartialSum + FileLength;
return NtHeaders;
}
DWORD
MapFileAndCheckSumW(
PWSTR Filename,
LPDWORD HeaderSum,
LPDWORD CheckSum
)
/*++
Routine Description:
This functions maps the specified file and computes the checksum of
the file.
Arguments:
Filename - Supplies a pointer to the name of the file whose checksum
is computed.
HeaderSum - Supplies a pointer to a variable that receives the checksum
from the image file, or zero if the file is not an image file.
CheckSum - Supplies a pointer to the variable that receive the computed
checksum.
Return Value:
0 if successful, else error number.
--*/
{
#ifndef UNICODE_RULES
CHAR FileNameA[ MAX_PATH ];
// Convert the file name to Ansi and call the Ansi version
// of this function.
if (WideCharToMultiByte(
CP_ACP,
0,
Filename,
-1,
FileNameA,
MAX_PATH,
NULL,
NULL ) ) {
return MapFileAndCheckSumA(FileNameA, HeaderSum, CheckSum);
}
return CHECKSUM_UNICODE_FAILURE;
#else // UNICODE_RULES
HANDLE FileHandle, MappingHandle;
LPVOID BaseAddress;
DWORD FileLength;
//
// Open the file for read access
//
FileHandle = CreateFileW(
Filename,
GENERIC_READ,
FILE_SHARE_READ | FILE_SHARE_WRITE,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL );
if (FileHandle == INVALID_HANDLE_VALUE) {
return CHECKSUM_OPEN_FAILURE;
}
//
// Create a file mapping, map a view of the file into memory,
// and close the file mapping handle.
//
MappingHandle = CreateFileMapping(FileHandle,
NULL,
PAGE_READONLY,
0,
0,
NULL);
if (!MappingHandle) {
CloseHandle( FileHandle );
return CHECKSUM_MAP_FAILURE;
}
//
// Map a view of the file
//
BaseAddress = MapViewOfFile(MappingHandle, FILE_MAP_READ, 0, 0, 0);
CloseHandle(MappingHandle);
if (BaseAddress == NULL) {
CloseHandle( FileHandle );
return CHECKSUM_MAPVIEW_FAILURE;
}
//
// Get the length of the file in bytes and compute the checksum.
//
FileLength = GetFileSize( FileHandle, NULL );
CheckSumMappedFile(BaseAddress, FileLength, HeaderSum, CheckSum);
//
// Unmap the view of the file and close file handle.
//
UnmapViewOfFile(BaseAddress);
CloseHandle( FileHandle );
return CHECKSUM_SUCCESS;
#endif // UNICODE_RULES
}
ULONG
MapFileAndCheckSumA (
LPSTR Filename,
LPDWORD HeaderSum,
LPDWORD CheckSum
)
/*++
Routine Description:
This functions maps the specified file and computes the checksum of
the file.
Arguments:
Filename - Supplies a pointer to the name of the file whose checksum
is computed.
HeaderSum - Supplies a pointer to a variable that receives the checksum
from the image file, or zero if the file is not an image file.
CheckSum - Supplies a pointer to the variable that receive the computed
checksum.
Return Value:
0 if successful, else error number.
--*/
{
#ifdef UNICODE_RULES
WCHAR FileNameW[ MAX_PATH ];
//
// Convert the file name to unicode and call the unicode version
// of this function.
//
if (MultiByteToWideChar(
CP_ACP,
MB_PRECOMPOSED,
Filename,
-1,
FileNameW,
MAX_PATH ) ) {
return MapFileAndCheckSumW(FileNameW, HeaderSum, CheckSum);
}
return CHECKSUM_UNICODE_FAILURE;
#else // UNICODE_RULES
HANDLE FileHandle, MappingHandle;
LPVOID BaseAddress;
DWORD FileLength;
//
// Open the file for read access
//
FileHandle = CreateFileA(
Filename,
GENERIC_READ,
FILE_SHARE_READ | FILE_SHARE_WRITE,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL );
if (FileHandle == INVALID_HANDLE_VALUE) {
return CHECKSUM_OPEN_FAILURE;
}
//
// Create a file mapping, map a view of the file into memory,
// and close the file mapping handle.
//
MappingHandle = CreateFileMapping(FileHandle,
NULL,
PAGE_READONLY,
0,
0,
NULL);
if (!MappingHandle) {
CloseHandle( FileHandle );
return CHECKSUM_MAP_FAILURE;
}
//
// Map a view of the file
//
BaseAddress = MapViewOfFile(MappingHandle, FILE_MAP_READ, 0, 0, 0);
CloseHandle(MappingHandle);
if (BaseAddress == NULL) {
CloseHandle( FileHandle );
return CHECKSUM_MAPVIEW_FAILURE;
}
//
// Get the length of the file in bytes and compute the checksum.
//
FileLength = GetFileSize( FileHandle, NULL );
CheckSumMappedFile(BaseAddress, FileLength, HeaderSum, CheckSum);
//
// Unmap the view of the file and close file handle.
//
UnmapViewOfFile(BaseAddress);
CloseHandle( FileHandle );
return CHECKSUM_SUCCESS;
#endif // UNICODE_RULES
}
BOOL
TouchFileTimes(
HANDLE FileHandle,
LPSYSTEMTIME lpSystemTime
)
{
SYSTEMTIME SystemTime;
FILETIME SystemFileTime;
if (lpSystemTime == NULL) {
lpSystemTime = &SystemTime;
GetSystemTime( lpSystemTime );
}
if (SystemTimeToFileTime( lpSystemTime, &SystemFileTime )) {
return SetFileTime( FileHandle, NULL, NULL, &SystemFileTime );
}
else {
return FALSE;
}
}