276 lines
7.3 KiB
C
276 lines
7.3 KiB
C
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/*++
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Copyright (c) 1995 Microsoft Corporation
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Module Name:
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syspart.c
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Abstract:
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Routines to determine the system partition on x86 machines.
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Author:
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Ted Miller (tedm) 30-June-1994
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Revision History:
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--*/
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#include "setupp.h"
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#pragma hdrstop
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BOOL
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AppearsToBeSysPart(
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IN PDRIVE_LAYOUT_INFORMATION DriveLayout,
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IN WCHAR Drive
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)
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{
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PARTITION_INFORMATION PartitionInfo,*p;
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BOOL IsPrimary;
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unsigned i;
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HANDLE FindHandle;
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WIN32_FIND_DATA FindData;
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PWSTR BootFiles[] = { L"BOOT.INI",
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L"NTLDR",
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L"NTDETECT.COM",
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NULL
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};
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WCHAR FileName[64];
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//
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// Get partition information for this partition.
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//
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if(!GetPartitionInfo(Drive,&PartitionInfo)) {
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return(FALSE);
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}
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//
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// See if the drive is a primary partition.
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//
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IsPrimary = FALSE;
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for(i=0; i<min(DriveLayout->PartitionCount,4); i++) {
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p = &DriveLayout->PartitionEntry[i];
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if((p->PartitionType != PARTITION_ENTRY_UNUSED)
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&& (p->StartingOffset.QuadPart == PartitionInfo.StartingOffset.QuadPart)
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&& (p->PartitionLength.QuadPart == PartitionInfo.PartitionLength.QuadPart)) {
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IsPrimary = TRUE;
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break;
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}
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}
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if(!IsPrimary) {
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return(FALSE);
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}
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//
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// Don't rely on the active partition flag. This could easily not be accurate
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// (like user is using os/2 boot manager, for example).
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//
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//
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// See whether nt boot files are present on this drive.
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//
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for(i=0; BootFiles[i]; i++) {
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wsprintf(FileName,L"%wc:\\%s",Drive,BootFiles[i]);
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FindHandle = FindFirstFile(FileName,&FindData);
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if(FindHandle == INVALID_HANDLE_VALUE) {
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return(FALSE);
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} else {
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FindClose(FindHandle);
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}
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}
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return(TRUE);
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}
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WCHAR
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x86DetermineSystemPartition(
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VOID
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)
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/*++
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Routine Description:
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Determine the system partition on x86 machines.
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The system partition is the primary partition on the boot disk.
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Usually this is the active partition on disk 0 and usually it's C:.
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However the user could have remapped drive letters and generally
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determining the system partition with 100% accuracy is not possible.
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The one thing we can be sure of is that the system partition is on
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the physical hard disk with the arc path multi(0)disk(0)rdisk(0).
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We can be sure of this because by definition this is the arc path
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for bios drive 0x80.
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This routine determines which drive letters represent drives on
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that physical hard drive, and checks each for the nt boot files.
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The first drive found with those files is assumed to be the system
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partition.
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If for some reason we cannot determine the system partition by the above
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method, we simply assume it's C:.
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Arguments:
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None.
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Return Value:
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Drive letter of system partition.
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--*/
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{
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BOOL GotIt;
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PWSTR NtDevicePath;
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WCHAR Drive;
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WCHAR DriveName[3];
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WCHAR Buffer[512];
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DWORD NtDevicePathLen;
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PWSTR p;
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DWORD PhysicalDriveNumber;
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HANDLE hDisk;
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BOOL b;
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DWORD DataSize;
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PVOID DriveLayout;
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DWORD DriveLayoutSize;
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DWORD hardDiskNumber;
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DriveName[1] = L':';
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DriveName[2] = 0;
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GotIt = FALSE;
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//
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// The system partition must be on multi(0)disk(0)rdisk(0)
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//
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if(NtDevicePath = ArcDevicePathToNtPath(L"multi(0)disk(0)rdisk(0)")) {
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//
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// The arc path for a disk device is usually linked
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// to partition0. Get rid of the partition part of the name.
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//
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CharLower(NtDevicePath);
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if(p = wcsstr(NtDevicePath,L"\\partition")) {
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*p = 0;
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}
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NtDevicePathLen = lstrlen(NtDevicePath);
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//
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// Determine the physical drive number of this drive.
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// If the name is not of the form \device\harddiskx then
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// something is very wrong.
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//
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if(!wcsncmp(NtDevicePath,L"\\device\\harddisk",16)) {
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PhysicalDriveNumber = wcstoul(NtDevicePath+16,NULL,10);
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wsprintf(Buffer,L"\\\\.\\PhysicalDrive%u",PhysicalDriveNumber);
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//
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// Get drive layout info for this physical disk.
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//
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hDisk = CreateFile(
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Buffer,
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GENERIC_READ,
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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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0,
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NULL
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);
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if(hDisk != INVALID_HANDLE_VALUE) {
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//
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// Get partition information.
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//
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DriveLayout = MyMalloc(1024);
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DriveLayoutSize = 1024;
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retry:
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b = DeviceIoControl(
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hDisk,
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IOCTL_DISK_GET_DRIVE_LAYOUT,
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NULL,
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0,
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DriveLayout,
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DriveLayoutSize,
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&DataSize,
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NULL
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);
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if(!b && (GetLastError() == ERROR_INSUFFICIENT_BUFFER)) {
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DriveLayoutSize += 1024;
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DriveLayout = MyRealloc(DriveLayout,DriveLayoutSize);
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goto retry;
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}
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CloseHandle(hDisk);
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if(b) {
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//
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// The system partition can only be a drive that is on
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// this disk. We make this determination by looking at NT drive names
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// for each drive letter and seeing if the nt equivalent of
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// multi(0)disk(0)rdisk(0) is a prefix.
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//
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for(Drive=L'C'; Drive<=L'Z'; Drive++) {
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if(MyGetDriveType(Drive) == DRIVE_FIXED) {
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DriveName[0] = Drive;
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if(QueryDosDevice(DriveName,Buffer,sizeof(Buffer)/sizeof(WCHAR))) {
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if (_wcsnicmp(Buffer, L"\\device\\harddisk", 16)) {
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hardDiskNumber = QueryHardDiskNumber((UCHAR) Drive);
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if (hardDiskNumber != (DWORD) -1) {
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swprintf(Buffer, TEXT("\\device\\harddisk%d"),
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hardDiskNumber);
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}
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}
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if(!_wcsnicmp(NtDevicePath,Buffer,NtDevicePathLen)) {
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//
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// Now look to see whether there's an nt boot sector and
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// boot files on this drive.
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//
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if(AppearsToBeSysPart(DriveLayout,Drive)) {
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GotIt = TRUE;
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break;
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}
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}
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}
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}
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}
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}
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MyFree(DriveLayout);
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}
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}
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MyFree(NtDevicePath);
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}
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return(GotIt ? Drive : L'C');
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}
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