403 lines
9 KiB
C
403 lines
9 KiB
C
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/*++
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Copyright (c) 1993 Microsoft Corporation
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Module Name:
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checksum.c
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Abstract:
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This module implements a function for computing the checksum of an
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image file. It will also compute the checksum of other files as well.
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Author:
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David N. Cutler 21-Mar-1993
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Revision History:
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--*/
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#include <windows.h>
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#include "checksum.h"
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#include "rlmsgtbl.h"
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void QuitA( int, LPSTR, LPSTR);
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void QuitW( int, LPWSTR, LPWSTR);
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// Helper routines
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static PIMAGE_NT_HEADERS ImageNtHeader( PVOID Base);
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static USHORT ChkSum( DWORD PartialSum,
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PUSHORT Source,
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DWORD Length);
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static PIMAGE_NT_HEADERS
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CheckSumMappedFile (
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LPVOID pBaseAddress,
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DWORD dwFileLength,
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LPDWORD pdwHeaderSum,
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LPDWORD pdwCheckSum
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);
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static BOOL
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TouchFileTimes (
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HANDLE hFileHandle,
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LPSYSTEMTIME lpSystemTime
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);
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/*++
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Routine Description:
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This function returns the address of the NT Header.
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Arguments:
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Base - Supplies the base of the image.
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Return Value:
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Returns the address of the NT Header.
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--*/
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static PIMAGE_NT_HEADERS ImageNtHeader( PVOID pBase)
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{
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PIMAGE_NT_HEADERS pNtHeaders = NULL;
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if ( pBase != NULL && pBase != (PVOID)-1 )
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{
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if ( ((PIMAGE_DOS_HEADER)pBase)->e_magic == IMAGE_DOS_SIGNATURE )
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{
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pNtHeaders = (PIMAGE_NT_HEADERS)((PCHAR)pBase + ((PIMAGE_DOS_HEADER)pBase)->e_lfanew);
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if ( pNtHeaders->Signature != IMAGE_NT_SIGNATURE )
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{
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pNtHeaders = NULL;
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}
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}
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}
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return( pNtHeaders);
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}
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/*++
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Routine Description:
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Compute a partial checksum on a portion of an imagefile.
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Arguments:
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PartialSum - Supplies the initial checksum value.
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Sources - Supplies a pointer to the array of words for which the
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checksum is computed.
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Length - Supplies the length of the array in words.
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Return Value:
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The computed checksum value is returned as the function value.
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--*/
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static USHORT ChkSum(
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ULONG PartialSum,
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PUSHORT Source,
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ULONG Length)
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{
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//
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// Compute the word wise checksum allowing carries to occur into the
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// high order half of the checksum longword.
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//
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while (Length--) {
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PartialSum += *Source++;
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PartialSum = (PartialSum >> 16) + (PartialSum & 0xffff);
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}
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//
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// Fold final carry into a single word result and return the resultant
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// value.
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//
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return (USHORT)(((PartialSum >> 16) + PartialSum) & 0xffff);
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}
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/*++
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Routine Description:
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This functions computes the checksum of a mapped file.
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Arguments:
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BaseAddress - Supplies a pointer to the base of the mapped file.
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FileLength - Supplies the length of the file in bytes.
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HeaderSum - Suppllies a pointer to a variable that receives the checksum
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from the image file, or zero if the file is not an image file.
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CheckSum - Supplies a pointer to the variable that receive the computed
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checksum.
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Return Value:
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None.
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--*/
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static PIMAGE_NT_HEADERS CheckSumMappedFile(
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LPVOID pBaseAddress,
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DWORD dwFileLength,
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LPDWORD pdwHeaderSum,
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LPDWORD pdwCheckSum)
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{
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USHORT usPartialSum;
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PUSHORT pusAdjustSum;
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PIMAGE_NT_HEADERS pNtHeaders = NULL;
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//
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// Compute the checksum of the file and zero the header checksum value.
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//
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*pdwHeaderSum = 0;
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usPartialSum = ChkSum(0, (PUSHORT)pBaseAddress, (dwFileLength + 1) >> 1);
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//
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// If the file is an image file, then subtract the two checksum words
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// in the optional header from the computed checksum before adding
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// the file length, and set the value of the header checksum.
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//
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pNtHeaders = ImageNtHeader( pBaseAddress);
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if ( (pNtHeaders != NULL) && (pNtHeaders != pBaseAddress) )
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{
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*pdwHeaderSum = pNtHeaders->OptionalHeader.CheckSum;
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pusAdjustSum = (PUSHORT)(&pNtHeaders->OptionalHeader.CheckSum);
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usPartialSum -= (usPartialSum < pusAdjustSum[0]);
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usPartialSum -= pusAdjustSum[0];
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usPartialSum -= (usPartialSum < pusAdjustSum[1]);
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usPartialSum -= pusAdjustSum[1];
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}
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//
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// Compute the final checksum value as the sum of the paritial checksum
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// and the file length.
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//
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*pdwCheckSum = (DWORD)usPartialSum + dwFileLength;
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return( pNtHeaders);
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}
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/*++
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Routine Description:
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This functions maps the specified file and computes the checksum of
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the file.
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Arguments:
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Filename - Supplies a pointer to the name of the file whose checksum
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is computed.
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HeaderSum - Supplies a pointer to a variable that receives the checksum
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from the image file, or zero if the file is not an image file.
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CheckSum - Supplies a pointer to the variable that receive the computed
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checksum.
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Return Value:
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0 if successful, else error number.
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--*/
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DWORD MapFileAndFixCheckSumW( PWSTR pszwFilename)
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{
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HANDLE hFileHandle = NULL;
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HANDLE hMappingHandle = NULL;
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LPVOID pBaseAddress = NULL;
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DWORD dwFileLength = 0;
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DWORD dwHeaderSum = 0;
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DWORD dwCheckSum = 0;
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DWORD dwOldCheckSum = 0;
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PIMAGE_NT_HEADERS pNtHeaders = NULL;
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//
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// Open the file for read access
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//
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hFileHandle = CreateFileW( pszwFilename,
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GENERIC_READ | GENERIC_WRITE,
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FILE_SHARE_READ | FILE_SHARE_WRITE,
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NULL,
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OPEN_EXISTING,
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FILE_ATTRIBUTE_NORMAL,
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NULL);
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if ( hFileHandle == INVALID_HANDLE_VALUE )
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{
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QuitW( IDS_ENGERR_01, L"image", pszwFilename);
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}
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//
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// Create a file mapping, map a view of the file into memory,
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// and close the file mapping handle.
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//
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hMappingHandle = CreateFileMapping( hFileHandle,
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NULL,
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PAGE_READWRITE,
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0,
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0,
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NULL);
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if ( hMappingHandle == NULL )
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{
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CloseHandle( hFileHandle );
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QuitW( IDS_ENGERR_22, pszwFilename, NULL);
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}
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//
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// Map a view of the file
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//
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pBaseAddress = MapViewOfFile( hMappingHandle,
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FILE_MAP_READ | FILE_MAP_WRITE,
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0,
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0,
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0);
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CloseHandle( hMappingHandle);
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if ( pBaseAddress == NULL )
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{
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CloseHandle( hFileHandle );
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QuitW( IDS_ENGERR_23, pszwFilename, NULL);
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}
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//
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// Get the length of the file in bytes and compute the checksum.
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//
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dwFileLength = GetFileSize( hFileHandle, NULL );
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pNtHeaders = CheckSumMappedFile( pBaseAddress, dwFileLength, &dwHeaderSum, &dwCheckSum);
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if ( pNtHeaders == NULL )
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{
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CloseHandle( hFileHandle );
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UnmapViewOfFile( pBaseAddress );
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QuitW( IDS_ENGERR_17, pszwFilename, NULL);
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}
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dwOldCheckSum = pNtHeaders->OptionalHeader.CheckSum;
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pNtHeaders->OptionalHeader.CheckSum = dwCheckSum;
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if ( ! FlushViewOfFile( pBaseAddress, dwFileLength) )
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{
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UnmapViewOfFile( pBaseAddress);
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CloseHandle( hFileHandle);
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QuitW( IDS_ENGERR_24, pszwFilename, NULL);
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}
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UnmapViewOfFile( pBaseAddress);
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if ( dwCheckSum != dwOldCheckSum )
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{
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if ( ! TouchFileTimes( hFileHandle, NULL) )
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{
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CloseHandle( hFileHandle);
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QuitW( IDS_ENGERR_25, pszwFilename, NULL);
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}
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}
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CloseHandle( hFileHandle);
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return( 0);
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}
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/*++
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Routine Description:
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This functions maps the specified file and computes the checksum of
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the file.
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Arguments:
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Filename - Supplies a pointer to the name of the file whose checksum
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is computed.
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HeaderSum - Supplies a pointer to a variable that receives the checksum
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from the image file, or zero if the file is not an image file.
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CheckSum - Supplies a pointer to the variable that receive the computed
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checksum.
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Return Value:
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0 if successful, else error number.
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--*/
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ULONG MapFileAndFixCheckSumA( LPSTR pszFilename)
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{
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WCHAR szFileNameW[ MAX_PATH ];
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//
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// Convert the file name to unicode and call the unicode version
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// of this function.
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//
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if ( MultiByteToWideChar( CP_ACP,
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MB_PRECOMPOSED,
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pszFilename,
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-1,
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szFileNameW,
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MAX_PATH) )
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{
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return( MapFileAndFixCheckSumW( szFileNameW));
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}
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return( (ULONG)-1L);
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}
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//.........................................
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static BOOL TouchFileTimes(
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HANDLE FileHandle,
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LPSYSTEMTIME lpSystemTime)
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{
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SYSTEMTIME SystemTime;
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FILETIME SystemFileTime;
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if ( lpSystemTime == NULL )
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{
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lpSystemTime = &SystemTime;
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GetSystemTime( lpSystemTime );
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}
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if ( SystemTimeToFileTime( lpSystemTime, &SystemFileTime ) )
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{
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return( SetFileTime( FileHandle, NULL, NULL, &SystemFileTime ));
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}
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else
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{
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return( FALSE);
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}
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}
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