windows-server-2003/inetsrv/iis/iisrearc/iisplus/ulw3/filecache.cxx

/*++

   Copyright    (c)    1999    Microsoft Corporation

   Module Name :
     filecache.cxx

   Abstract:
     A file cache (filename->W3_FILE_INFO cache)
 
   Author:
     Bilal Alam (balam)             11-Nov-2000

   Environment:
     Win32 - User Mode

   Project:
     ULW3.DLL
--*/

#include "precomp.hxx"

#define STRONG_ETAG_DELTA       30000000

#define SIZE_PRIVILEGE_SET                      128

ALLOC_CACHE_HANDLER *    W3_FILE_INFO::sm_pachW3FileInfo;

GENERIC_MAPPING g_gmFile = {
    FILE_GENERIC_READ,
    FILE_GENERIC_WRITE,
    FILE_GENERIC_EXECUTE,
    FILE_ALL_ACCESS
};

HRESULT
W3_FILE_INFO_KEY::CreateCacheKey(
    WCHAR *             pszFileKey,
    DWORD               cchFileKey,
    BOOL                fCopy
)
/*++

Routine Description:

    Initialize a file cache key

Arguments:

    pszFileKey - filename
    cchFileKey - size of filename
    fCopy - TRUE if we should copy into key buffer, otherwise just keep ref

Return Value:

    HRESULT

--*/
{
    HRESULT             hr;
    
    if ( fCopy )
    {
        hr = _strFileKey.Copy( pszFileKey );
        if ( FAILED( hr ) )
        {
            return hr;
        }
        
        _pszFileKey = _strFileKey.QueryStr();
        _cchFileKey = _strFileKey.QueryCCH();
    }
    else
    {
        _pszFileKey = pszFileKey;
        _cchFileKey = cchFileKey;
    }

    return NO_ERROR;
}

W3_FILE_INFO::~W3_FILE_INFO(
    VOID
)
{
    HRESULT             hr;
    W3_FILE_INFO_CACHE* pFileCache;
    
    DBG_ASSERT( CheckSignature() );
    
    _dwSignature = W3_FILE_INFO_SIGNATURE_FREE;

    //
    // Clear any associated object
    //
    
    LockCacheEntry();
    
    if ( _pAssociatedObject != NULL )
    {
        _pAssociatedObject->Cleanup();
        _pAssociatedObject = NULL;
    }

    UnlockCacheEntry();

    //
    // Release the contents buffer if it exists
    //
    
    if ( _pFileBuffer != NULL )
    {
        pFileCache = (W3_FILE_INFO_CACHE*) QueryCache();
        
        hr = pFileCache->ReleaseFromMemoryCache( _pFileBuffer,
                                                 _nFileSizeLow );
        DBG_ASSERT( SUCCEEDED( hr ) );
        
        _pFileBuffer = NULL;
    }
    
    //
    // Close the file handle if it still around
    //
    
    if ( _hFile != INVALID_HANDLE_VALUE )
    {
        CloseHandle( _hFile );
        
        _hFile = INVALID_HANDLE_VALUE;
    }
}

BOOL
W3_FILE_INFO::SetAssociatedObject(
    ASSOCIATED_FILE_OBJECT *        pObject
)
/*++

Routine Description:

    Associate object with this cache entry

Arguments:

    pObject - Object to associate

Return Value:

    BOOL

--*/
{
    BOOL            fRet = FALSE;
    
    LockCacheEntry();
    
    if ( _pAssociatedObject == NULL )
    {
        _pAssociatedObject = pObject;
        fRet = TRUE;
    }
    
    UnlockCacheEntry();
    
    return fRet;
}

PSECURITY_DESCRIPTOR
W3_FILE_INFO::QuerySecDesc(
    VOID
)
/*++

Routine Description:

    Return security descriptor

Arguments:

    None

Return Value:

    pointer to security descriptor

--*/
{
    if ( _hFile != INVALID_HANDLE_VALUE )
    {
        if ( FAILED( ReadSecurityDescriptor() ) )
        {
            return NULL;
        }
    } 
    else
    {
        //
        // The file is cached, therefore we must have security already
        //
    }
        
    return _bufSecDesc.QueryPtr();
}

HRESULT
W3_FILE_INFO::GenerateETag(
    VOID
)
/*++

Routine Description:

    Generate ETag string

Arguments:

    None

Return Value:

    HRESULT

--*/
{
    CHAR *      psz = _achETag;
    PBYTE       pbTime = (PBYTE) &_ftLastWriteTime;
    DWORD       dwChangeNumber;
    const CHAR  szHex[] = "0123456789abcdef";
    FILETIME    ftNow;
    __int64     iNow;
    __int64     iFileTime;

    //
    // Is this ETag weak?  If so put the preceding W/
    //
    
    GetSystemTimeAsFileTime(&ftNow);
    iNow = (__int64)*(__int64 *)&ftNow;
    iFileTime = (__int64)*(__int64 *)&_ftLastWriteTime;

    if ( ( iNow - iFileTime ) <= STRONG_ETAG_DELTA )
    {
        //
        // This is a weak ETag
        //
        
        *psz++ = 'W';
        *psz++ = '/';
    }
    
    //
    // System change number is from the metabase
    //

    dwChangeNumber = g_pW3Server->QuerySystemChangeNumber();

    //
    // Generate the meat of the ETag
    //

    *psz++ = '\"';
    for (int i = 0; i < 8; i++)
    {
        BYTE b = *pbTime++;
        BYTE bH = b >> 4;
        if (bH != 0)
            *psz++ = szHex[bH];
        *psz++ = szHex[b & 0xF];
    }
    *psz++ = ':';
    psz += strlen(_itoa((DWORD) dwChangeNumber, psz, 16));
    *psz++ = '\"';
    *psz = '\0';

    _cchETag = DIFF(psz - _achETag);
    
    return NO_ERROR;
}

HRESULT
W3_FILE_INFO::GenerateLastModifiedTimeString(
    VOID
)
/*++

Routine Description:

    Generate the Last-Modified-Time header string

Arguments:

    None

Return Value:

    HRESULT

--*/
{
    SYSTEMTIME              st;
    
    FileTimeToSystemTime( &_ftLastWriteTime, &st );
                          
    if ( !SystemTimeToGMT( st, 
                           _achLastModified, 
                           sizeof(_achLastModified) ) ) 
    {  
        return HRESULT_FROM_WIN32( GetLastError() );
    }
    else
    {
        return NO_ERROR;
    }
}

HRESULT
W3_FILE_INFO::DoAccessCheck(
    CACHE_USER *   pFileCacheUser
)
/*++

Routine Description:

    Check whether given token has access to this file

Arguments:

    pFileCacheUser - User to access cache with

Return Value:

    HRESULT

--*/
{
    BYTE    psFile[SIZE_PRIVILEGE_SET];
    DWORD   dwPS;
    DWORD   dwGrantedAccess;
    BOOL    fAccess;
    
    if ( pFileCacheUser == NULL )
    {
        DBG_ASSERT( FALSE );
        return HRESULT_FROM_WIN32( ERROR_INVALID_PARAMETER );
    }
    
    //
    // If we don't have a security descriptor, then local system must have
    // accessed the file originally.  Just return success
    //
    
    if ( pFileCacheUser->_hToken == NULL )
    {
        return NO_ERROR;
    }
    
    //
    // If we have a last-user-sid, and the caller provided a sid, then do a
    // quick check of sid equality
    //
    
    if ( QueryLastSid() != NULL &&
         pFileCacheUser->_pSid != NULL )
    {
        if ( EqualSid( QueryLastSid(), pFileCacheUser->_pSid ) )
        {
            return NO_ERROR;
        }
    }
    
    if ( ISUNC( QueryPhysicalPath() ) )
    {
        //
        // If this is a UNC file, and the webserver and the UNC server
        // are not on a domain, the sid of the user on the webserver will
        // not match the sid in the security-descriptor, so AccessCheck will
        // fail, instead do GetFileAttributes
        //
        if ( !SetThreadToken( NULL, pFileCacheUser->_hToken ) )
        {
            return HRESULT_FROM_WIN32( GetLastError() );
        }
        ThreadPoolSetInfo( ThreadPoolIncMaxPoolThreads, 0 );

        DWORD dwAttributes = GetFileAttributes(QueryPhysicalPath());
        DWORD dwErr = GetLastError();

        ThreadPoolSetInfo( ThreadPoolDecMaxPoolThreads, 0 );
        DBG_REQUIRE( RevertToSelf() );

        if ( dwAttributes == INVALID_FILE_ATTRIBUTES )
        {
            return HRESULT_FROM_WIN32( dwErr );
        }
    }
    else
    {
        //
        // Ok.  Just use the token and cached security descriptor
        //

        dwPS = sizeof(psFile);
        ((PRIVILEGE_SET*)&psFile)->PrivilegeCount = 0;

        //
        // We must have a security descriptor if we've cached the file
        //

        DBG_ASSERT( QuerySecDesc() );

        if ( !AccessCheck( QuerySecDesc(),
                           pFileCacheUser->_hToken,
                           FILE_GENERIC_READ,
                           &g_gmFile,
                           (PRIVILEGE_SET*)psFile,
                           &dwPS,
                           &dwGrantedAccess,
                           &fAccess ) || !fAccess )
        {
            return HRESULT_FROM_WIN32( ERROR_ACCESS_DENIED );
        }
    }
    
    return NO_ERROR;
}

HRESULT
W3_FILE_INFO::OpenFile(
    STRU &          strFileName,
    CACHE_USER *    pOpeningUser,
    BOOL            fBufferFile
)
/*++

Routine Description:

    Open the given file (but don't read in the file contents).  This method
    does the minimum needed to allow the caller to make a reasonable 
    decision about whether this file should be cached here or in UL

Arguments:

    strFileName - file name to open
    pOpeningUser - User to open file under
    fBufferFile - Should the file be opened with FILE_FLAG_NO_BUFFERING?

Return Value:

    HRESULT

--*/
{
    HANDLE                  hFile = INVALID_HANDLE_VALUE;
    STACK_STRU(             strFilePath, MAX_PATH + 1 );
    HRESULT                 hr = NO_ERROR;
    BOOL                    fImpersonated = FALSE;
    BY_HANDLE_FILE_INFORMATION FileInfo; 
    DWORD                   dwFileType;
    BOOL                    bRet;

    if ( pOpeningUser == NULL )
    {
        DBG_ASSERT( FALSE );
        return HRESULT_FROM_WIN32( ERROR_INVALID_PARAMETER );
    }

    //
    // Turn off NT file canonicalization
    //

    hr = MakePathCanonicalizationProof( strFileName.QueryStr(),
                                        &strFilePath );
    if ( FAILED( hr ) )
    {
        goto Finished;
    }

    //    
    // Avoid the infamous ::$DATA bug
    //

    if ( wcschr( strFileName.QueryStr() + 6, L':' ) != NULL )
    {
        hr = HRESULT_FROM_WIN32( ERROR_FILE_NOT_FOUND );
        goto Finished;
    }

    //
    // We may need to impersonate some other user to open the file
    //

    if ( pOpeningUser->_hToken != NULL )
    {
        if ( !SetThreadToken( NULL, pOpeningUser->_hToken ) )
        {
            hr = HRESULT_FROM_WIN32( GetLastError() );
            goto Finished;
        }
        fImpersonated = TRUE;
    }

    //
    // Open the file.  CreateFile() perf can be underwhelming.  We'll need to 
    // potentially let out another thread while making the call.  Much
    // like we do for calls into ISAPI extensions
    //

    ThreadPoolSetInfo( ThreadPoolIncMaxPoolThreads, 0 );

    hFile = CreateFile( strFilePath.QueryStr(),
                        GENERIC_READ,
                        FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
                        NULL,
                        OPEN_EXISTING,
                        FILE_ATTRIBUTE_ENCRYPTED | FILE_DIRECTORY_FILE | FILE_FLAG_OVERLAPPED | FILE_FLAG_BACKUP_SEMANTICS | (fBufferFile ? 0 : FILE_FLAG_NO_BUFFERING),
                        NULL );

    if ( hFile == INVALID_HANDLE_VALUE )
    {
        hr = HRESULT_FROM_WIN32( GetLastError() );
    }
    
    //
    // Undo the threshold adjustment
    //
    
    ThreadPoolSetInfo( ThreadPoolDecMaxPoolThreads, 0 );

    if ( FAILED(hr) )
    {
        goto Finished;
    }

    //
    // Stop impersonating
    // 

    if ( fImpersonated )
    {
        RevertToSelf();
        fImpersonated = FALSE;
    }

    //
    // We shouldn't be opening byte streams (like COM, LPT)
    //

    dwFileType = GetFileType( hFile );
    if ( dwFileType != FILE_TYPE_DISK )
    {
        hr = HRESULT_FROM_WIN32( ERROR_FILE_NOT_FOUND );
        
        CloseHandle( hFile );
        hFile = INVALID_HANDLE_VALUE;
        
        goto Finished;
    }

    //
    // Get file attributes
    //

    bRet = GetFileInformationByHandle( hFile, &FileInfo );
    if ( !bRet )
    {
        hr = HRESULT_FROM_WIN32( GetLastError() );

        CloseHandle( hFile );
        hFile = INVALID_HANDLE_VALUE;
        
        goto Finished;
    }

    //
    // Set the minimum properties now
    //

    _hFile = hFile;
    hFile = INVALID_HANDLE_VALUE;
    _ftLastWriteTime = FileInfo.ftLastWriteTime;
    _dwFileAttributes = FileInfo.dwFileAttributes;
    _nFileSizeLow   = FileInfo.nFileSizeLow;
    _nFileSizeHigh  = FileInfo.nFileSizeHigh;

    *((__int64 *)&_CastratedLastWriteTime)
        = (*((__int64 *)&_ftLastWriteTime) / 10000000) * 10000000;

    //
    // Create the ETag and LastModified strings
    //

    hr = GenerateETag();
    if ( FAILED( hr ) )
    {
        goto Finished;
    }

    hr = GenerateLastModifiedTimeString();
    if ( FAILED( hr ) )
    {
        goto Finished;
    }

    _msLastAttributeCheckTime = GetTickCount();

    //
    // Turn off the hidden attribute if this is a root directory listing
    // (root some times has the bit set for no apparent reason)
    //

    if ( _dwFileAttributes & FILE_ATTRIBUTE_HIDDEN )
    {
        if ( strFileName.QueryCCH() >= 2 )
        {
            if ( strFileName.QueryStr()[ 1 ] == L':' )
            {
                if ( ( strFileName.QueryStr()[ 2 ] == L'\0' ) ||
                     ( strFileName.QueryStr()[ 2 ] == L'\\' && 
                       strFileName.QueryStr()[ 3 ] == L'\0' ) )
                {
                    //
                    // This looks like a local root.  Mask out the bit
                    //
            
                    _dwFileAttributes &= ~FILE_ATTRIBUTE_HIDDEN;
                }
            }
        }
    }

Finished:

    if ( FAILED( hr ) )
    {
        if ( fImpersonated )
        {
            RevertToSelf();
            fImpersonated = FALSE;
        }

        if ( hFile != INVALID_HANDLE_VALUE )
        {
            CloseHandle( hFile );
            hFile = INVALID_HANDLE_VALUE;
        }
    }

    return hr;
}

HRESULT
W3_FILE_INFO::ReadSecurityDescriptor(
    VOID
)
/*++

Routine Description:

    Read security descriptor for current file

Arguments:

    None

Return Value:

    HRESULT

--*/
{
    DWORD                   cbRequired;
    
    
    //
    // Cache the security descriptor
    //
    
    if ( !GetKernelObjectSecurity( _hFile,
                                   OWNER_SECURITY_INFORMATION
                                   | GROUP_SECURITY_INFORMATION
                                   | DACL_SECURITY_INFORMATION,
                                    (PSECURITY_DESCRIPTOR) _bufSecDesc.QueryPtr(),
                                   _bufSecDesc.QuerySize(),
                                   &cbRequired ) )
    {
        if ( GetLastError() != ERROR_INSUFFICIENT_BUFFER )
        {
            return HRESULT_FROM_WIN32( GetLastError() );
        }
        
        DBG_ASSERT( cbRequired > _bufSecDesc.QuerySize() );
            
        if ( !_bufSecDesc.Resize( cbRequired ) )
        {
            return HRESULT_FROM_WIN32( GetLastError() );
        }
        
        //
        // Try again with the bigger buffer.  No more excuses
        //
        
        if ( !GetKernelObjectSecurity( _hFile,
                                       OWNER_SECURITY_INFORMATION
                                       | GROUP_SECURITY_INFORMATION
                                       | DACL_SECURITY_INFORMATION,
                                       (PSECURITY_DESCRIPTOR) _bufSecDesc.QueryPtr(),
                                       _bufSecDesc.QuerySize(),
                                       &cbRequired ) )
        {
            return HRESULT_FROM_WIN32( GetLastError() );
        }
    }
    
    return NO_ERROR;
}

HRESULT
W3_FILE_INFO::MakeCacheable(
    CACHE_USER        *pFileUser,
    FILE_CACHE_ASYNC_CONTEXT *pAsyncContext,
    BOOL              *pfHandledSync,
    BOOL               fCheckForExistenceOnly
)
/*++

Routine Description:

    Make the file cacheable by reading contents into memory, and caching
    the security descriptor

Arguments:

    pFileUser - User trying to open file
    pAsyncContext - Provides the information necessary to notify the caller
                    when the file has been read when done async
    pfHandledSync - If provided, on return tells whether the open completed
                    synchronously
    fCheckForExistenceOnly - Are we caching the state of existence only?

Return Value:

    HRESULT

--*/
{
    HRESULT                 hr;
    W3_FILE_INFO_CACHE*     pFileCache;

    if ( pFileUser == NULL )
    {
        DBG_ASSERT( FALSE );
        return HRESULT_FROM_WIN32( ERROR_INVALID_PARAMETER );
    }

    DBG_ASSERT( IsCacheable() );

    //
    // We must have a file handle if we're here
    //

    DBG_ASSERT( _hFile != INVALID_HANDLE_VALUE );

    //
    // Get the security descriptor
    //

    hr = ReadSecurityDescriptor();
    if ( FAILED( hr ) )
    {
        return hr;
    }

    //
    // On top of reading the security descriptor, we will also store the
    // last sid accessing the file if available
    //

    if ( pFileUser->_pSid != NULL )
    {
        if ( GetLengthSid( pFileUser->_pSid ) <= sizeof( _abLastSid ) )
        {
            memcpy( _abLastSid, 
                    pFileUser->_pSid,
                    GetLengthSid( pFileUser->_pSid ) );
            
            _pLastSid = (PSID) _abLastSid;
        }
    }

    //
    // Now read the contents of the file into memory since we cannot cache
    // the file handle itself
    //

    if ( _nFileSizeHigh > 0 )
    {
        return HRESULT_FROM_WIN32(ERROR_NOT_ENOUGH_MEMORY);
    }
    
    //
    // If we're just caching a descriptor to check the existence of the file,
    // then we don't need to read the file contents
    //
    
    if ( fCheckForExistenceOnly )
    {
        CloseHandle( _hFile );
        _hFile = INVALID_HANDLE_VALUE;
       
        DBG_ASSERT( _pFileBuffer == NULL );
        
        return NO_ERROR;
    }

    //
    // Set up the context for completion
    //

    if ( pAsyncContext != NULL )
    {
        pAsyncContext->pFileInfo = this;
    }

    pFileCache = (W3_FILE_INFO_CACHE*) QueryCache();

    //
    // Read the file
    //

    hr = pFileCache->ReadFileIntoMemoryCache( _hFile,
                                              _nFileSizeLow,
                                              (PVOID*) &_pFileBuffer,
                                              pAsyncContext,
                                              pfHandledSync );

    if ( FAILED( hr ) )
    {
        if ( pAsyncContext != NULL )
        {
            pAsyncContext->pFileInfo = NULL;
        }
    }
    else if ( pfHandledSync == NULL || *pfHandledSync )
    {
        CloseHandle( _hFile );
        _hFile = INVALID_HANDLE_VALUE;
    }

    return hr;
}

BOOL
W3_FILE_INFO::IsCacheable(
    VOID
) const
/*++

Routine Description:

    Is this file cacheable?  Specically, we should we even attempt to cache
    this file?

Arguments:

    None

Return Value:

    TRUE if cacheable 

--*/
{
    W3_FILE_INFO_CACHE *    pFileCache;
   
    pFileCache = (W3_FILE_INFO_CACHE*) QueryCache();
    DBG_ASSERT( pFileCache != NULL );

    //
    // Are we past the limit of file entries?
    //
    
    if ( pFileCache->QueryElementLimitExceeded() )
    {
        return FALSE;
    }

    return IsUlCacheable();
}

BOOL
W3_FILE_INFO::IsUlCacheable(
    VOID
) const
/*++

Routine Description:

    Is this file cacheable?  Specically, we should we even attempt to cache
    this file?

Arguments:

    None

Return Value:

    TRUE if cacheable 

--*/
{
    LARGE_INTEGER           liFileSize;
    W3_FILE_INFO_CACHE *    pFileCache;
   
    pFileCache = (W3_FILE_INFO_CACHE*) QueryCache();
    DBG_ASSERT( pFileCache != NULL );

    //
    // No caching of directories
    //
    
    if ( _dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY )
    {
        return FALSE;
    }
    
    //
    // No caching of encrypted files
    //
    
    if ( _dwFileAttributes & FILE_ATTRIBUTE_ENCRYPTED )
    {
        return FALSE;
    }
    
    //
    // No caching of file sizes greater than the configured threshold
    //
    
    liFileSize.LowPart = _nFileSizeLow;
    liFileSize.HighPart = _nFileSizeHigh;

    if ( liFileSize.QuadPart > pFileCache->QueryFileSizeThreshold() )
    {
        return FALSE;
    }

    return TRUE;
}

BOOL
W3_FILE_INFO::QueryIsOkToFlushDirmon(
    WCHAR *                 pszPath,
    DWORD                   cchPath
)
/*++

Routine Description:

    Determine whether this file entry should be flushed, given the path
    which has changed (dir monitor changed)

Arguments:

    pszPath - Path which changed
    cchPath - Size of path changed

Return Value:

    TRUE if we should flush, else FALSE

--*/
{
    DBG_ASSERT( _cacheKey._pszFileKey != NULL );
    
    if ( _wcsnicmp( _cacheKey._pszFileKey,
                    pszPath,
                    cchPath ) == 0 )
    {
        return TRUE;
    }
    else
    {
        return FALSE;
    }
}

//static
HRESULT
W3_FILE_INFO::Initialize(
    VOID
)
/*++

Routine Description:

    Initialize W3_FILE_INFO lookaside

Arguments:

    None

Return Value:

    HRESULT

--*/
{
    ALLOC_CACHE_CONFIGURATION   acConfig;
    HRESULT                     hr;    

    //
    // Initialize allocation lookaside
    //    
    
    acConfig.nConcurrency = 1;
    acConfig.nThreshold   = 100;
    acConfig.cbSize       = sizeof( W3_FILE_INFO );

    DBG_ASSERT( sm_pachW3FileInfo == NULL );
    
    sm_pachW3FileInfo = new ALLOC_CACHE_HANDLER( "W3_FILE_INFO",  
                                                &acConfig );

    if ( sm_pachW3FileInfo == NULL )
    {
        hr = HRESULT_FROM_WIN32( ERROR_NOT_ENOUGH_MEMORY );

        DBGPRINTF(( DBG_CONTEXT,
                   "Error initializing sm_pachW3FileInfo. hr = 0x%x\n",
                   hr ));

        return hr;
    }
    
    return NO_ERROR;
}

//static
VOID
W3_FILE_INFO::Terminate(
    VOID
)
/*++

Routine Description:

    Cleanup W3_FILE_INFO lookaside

Arguments:

    None

Return Value:

    None

--*/
{
    if ( sm_pachW3FileInfo != NULL )
    {
        delete sm_pachW3FileInfo;
        sm_pachW3FileInfo = NULL;
    }
}

//static
VOID
W3_FILE_INFO_CACHE::MemoryCacheAdjustor(
    PVOID               pCache,
    BOOLEAN             TimerOrWaitFired
)
/*++

Routine Description:

    Called to adjust our memory cache size if necessary

Arguments:

    pCache - Points to file cache

Return Value:

    None

--*/
{
    W3_FILE_INFO_CACHE *        pFileCache;
    MEMORYSTATUSEX              MemoryStatus;
    
    pFileCache = (W3_FILE_INFO_CACHE*) pCache;

    MemoryStatus.dwLength = sizeof( MemoryStatus );

    GlobalMemoryStatusEx( &MemoryStatus );
    
    EnterCriticalSection( &( pFileCache->_csMemCache ) );

    pFileCache->_cbMemCacheLimit = min( 
            MemoryStatus.ullAvailPhys + pFileCache->_cbMemCacheCurrentSize,
            MemoryStatus.ullTotalVirtual ) / 2;

    LeaveCriticalSection( &( pFileCache->_csMemCache ) );
}

W3_FILE_INFO_CACHE::W3_FILE_INFO_CACHE()
{
    _cbFileSizeThreshold = DEFAULT_FILE_SIZE_THRESHOLD;
    _cmsecFileAttributeCheckThreshold = DEFAULT_FILE_ATTRIBUTE_CHECK_THRESHOLD * 1000;
    _cbMemoryCacheSize = 0;
    _cMaxFileEntries = 0;
    _cbMemCacheLimit = 0;
    _cbMemCacheCurrentSize = 0;
    _cbMaxMemCacheSize = 0;
    _hMemCacheHeap = NULL;
    _hTimer = NULL;
    _fEnableCache = TRUE;
    _fDoDirmonForUnc = FALSE;
}

W3_FILE_INFO_CACHE::~W3_FILE_INFO_CACHE()
{
}

HRESULT
W3_FILE_INFO_CACHE::InitializeMemoryCache(
    VOID
)
/*++

Routine Description:

    Initialize the memory cache

Arguments:

    None

Return Value:

    HRESULT

--*/
{
    BOOL                    fRet;
    HRESULT                 hr = NO_ERROR;

    fRet = INITIALIZE_CRITICAL_SECTION( &_csMemCache );
    if ( !fRet )
    {
        return HRESULT_FROM_WIN32( GetLastError() );
    }
    
    //
    // If the memory cache size was not explicitly set, then we occasionally
    // check memory status when determining what to cache
    // 

    if ( _cbMemoryCacheSize == 0 )
    {
        MEMORYSTATUSEX          MemoryStatus;
        
        MemoryStatus.dwLength = sizeof( MemoryStatus );
    
        // 
        // Get our own estimate of size of cache
        //
        
        GlobalMemoryStatusEx( &MemoryStatus );
        
        _cbMemCacheLimit = min( MemoryStatus.ullAvailPhys,
                                MemoryStatus.ullTotalVirtual ) / 2;
    
        //
        // Setup timer so we can update our memory status
        //
                                  
        fRet = CreateTimerQueueTimer( &_hTimer,
                                      NULL,
                                      W3_FILE_INFO_CACHE::MemoryCacheAdjustor,
                                      this,
                                      30000,
                                      30000,
                                      WT_EXECUTELONGFUNCTION );
        if ( !fRet )
        {
            hr = HRESULT_FROM_WIN32( GetLastError() );
        }
    }
    else
    {   
        _cbMemCacheLimit = _cbMemoryCacheSize;
    }
    
    //
    // Allocate a private heap
    //
    
    if ( SUCCEEDED( hr ) ) 
    {
        _hMemCacheHeap = HeapCreate( 0, 0, 0 );
        if ( _hMemCacheHeap == NULL )
        {
            hr = HRESULT_FROM_WIN32( GetLastError() );
        }
    }

    if ( FAILED( hr ) )
    {
        if ( _hMemCacheHeap != NULL )
        {
            HeapDestroy( _hMemCacheHeap );
            _hMemCacheHeap = NULL;
        }
        
        if ( _hTimer != NULL )
        {
            DeleteTimerQueueTimer( NULL,
                                   _hTimer, 
                                   INVALID_HANDLE_VALUE );
            _hTimer = NULL;
        }
        
        DeleteCriticalSection( &_csMemCache );
    }
    
    return hr;
}

HRESULT
W3_FILE_INFO_CACHE::ReadFileIntoMemoryCache( 
    IN HANDLE               hFile,
    IN DWORD                cbFile,
    OUT VOID **             ppvBuffer,
    IN FILE_CACHE_ASYNC_CONTEXT *pAsyncContext,
    OUT BOOL               *pfHandledSync
)
/*++

Routine Description:

    Read contents of file into a buffer

Arguments:

    hFile - Handle to valid file
    cbFile - Size of file ( ==> size of buffer )
    ppvBuffer - Filled in with pointer to buffer with file contents.  Set
                to NULL on failure
    pAsyncContext - Provides the information necessary to notify the caller
                    when the file has been read when done async
    pfHandledSync - If provided, on return tells whether the open completed
                    synchronously

Return Value:

    HRESULT

--*/
{
    BOOL                    bRet;
    VOID *                  pvBuffer = NULL;
    DWORD                   cbRead;
    OVERLAPPED              Overlapped;
    HRESULT                 hr = NO_ERROR;

    DBG_ASSERT( hFile && ( hFile != INVALID_HANDLE_VALUE ) );
    DBG_ASSERT( ppvBuffer != NULL );

    ZeroMemory( &Overlapped, sizeof(Overlapped) );

    //
    // First check whether there will be room in cache for the blob 
    //

    EnterCriticalSection( &_csMemCache );
    
    if ( ( _cbMemCacheCurrentSize + cbFile ) > _cbMemCacheLimit ) 
    {
        // 
        // Not enough room for cache
        //
        
        LeaveCriticalSection( &_csMemCache );

        return HRESULT_FROM_WIN32( ERROR_NOT_ENOUGH_MEMORY );
    }
    
    _cbMemCacheCurrentSize += cbFile;
    
    _cbMaxMemCacheSize = max( _cbMaxMemCacheSize, _cbMemCacheCurrentSize );

    LeaveCriticalSection( &_csMemCache );

    //
    // Allocate blob for file
    //

    DBG_ASSERT( _hMemCacheHeap != NULL );
    pvBuffer = HeapAlloc( _hMemCacheHeap, 0, cbFile );
    if ( pvBuffer == NULL )
    {
        hr = HRESULT_FROM_WIN32( GetLastError() );
        goto Finished;
    }

    *ppvBuffer = pvBuffer;

    if (pAsyncContext != NULL)
    {
        ZeroMemory( &pAsyncContext->Overlapped, sizeof(pAsyncContext->Overlapped) );

        //
        // We can restrict what files we do async reads on further
        //

        if (!ThreadPoolBindIoCompletionCallback( hFile,
                                                 W3_FILE_INFO::FileReadCompletion,
                                                 0 ))
        {
            pAsyncContext = NULL;
            *pfHandledSync = TRUE;
            pfHandledSync = NULL;
        }
    }

    //
    // Read file into blob
    //

    bRet = ReadFile( hFile,
                     pvBuffer,
                     cbFile,
                     pAsyncContext ? NULL : &cbRead,
                     pAsyncContext ? &pAsyncContext->Overlapped : &Overlapped );

    if (!bRet)
    {

        hr = HRESULT_FROM_WIN32( GetLastError() );

        if ( hr != HRESULT_FROM_WIN32( ERROR_IO_PENDING ) )
        {
            //
            // Something bad happened
            //

            goto Finished;
        }

        //
        // Reset the error lest we confuse ourselves later on cleanup
        //

        hr = NO_ERROR;

        //
        // If async is ok, return now
        //

        if (pAsyncContext != NULL)
        {
            *pfHandledSync = FALSE;
            goto Finished;
        }

        //
        // Wait for async read to complete (if async is not ok)
        //

        bRet = GetOverlappedResult( hFile,
                                    &Overlapped,
                                    &cbRead,
                                    TRUE );
        if ( !bRet )
        {
            //
            // Something bad happened
            //

            hr = HRESULT_FROM_WIN32( GetLastError() );
            goto Finished;
        }
    }

    if (pAsyncContext != NULL)
    {
        *pfHandledSync = FALSE;
        goto Finished;
    }

    //
    // Ensure that we read the number of bytes we expected to
    //
    
    if ( cbRead != cbFile )
    {
        hr = HRESULT_FROM_WIN32( ERROR_INVALID_DATA );
    }


Finished:

    if ( FAILED( hr ) )
    {
        *ppvBuffer = NULL;

        //
        // Undo changes to memory cache statistics
        //
        
        EnterCriticalSection( &_csMemCache );

        _cbMemCacheCurrentSize -= cbFile;

        LeaveCriticalSection( &_csMemCache );
    
        if ( pvBuffer != NULL )
        {
            HeapFree( _hMemCacheHeap, 0, pvBuffer );
            pvBuffer = NULL;
        }
    }

    return hr;
}

HRESULT
W3_FILE_INFO_CACHE::ReleaseFromMemoryCache(
    IN VOID *                  pvBuffer,
    IN DWORD                   cbBuffer
)
/*++
Routine Description:

    Release file content blob from cache

Arguments:

    pvBuffer - Buffer to release
    cbBuffer - Size of buffer

Return Value:

    HRESULT

--*/
{
    DBG_ASSERT( pvBuffer );

    DBG_ASSERT( _hMemCacheHeap != NULL);

    HeapFree( _hMemCacheHeap, 0, pvBuffer );
    
    EnterCriticalSection( &_csMemCache );
    
    _cbMemCacheCurrentSize -= cbBuffer;

    LeaveCriticalSection( &_csMemCache );    

    return NO_ERROR;    
}

VOID
W3_FILE_INFO_CACHE::TerminateMemoryCache(
    VOID
)
/*++

Routine Description:

    Terminate memory cache

Arguments:

Return Value:

    None

--*/
{
    if ( _hTimer != NULL )
    {
        DeleteTimerQueueTimer( NULL,
                               _hTimer, 
                               INVALID_HANDLE_VALUE );
        _hTimer = NULL;
    }
    
    if ( _hMemCacheHeap != NULL )
    {
        HeapDestroy( _hMemCacheHeap );
        _hMemCacheHeap = NULL;
    }

    DeleteCriticalSection( &_csMemCache );
}

HRESULT
W3_FILE_INFO_CACHE::GetFileInfo(
    STRU &                  strFileName,
    DIRMON_CONFIG *         pDirmonConfig,
    CACHE_USER *            pOpeningUser,
    BOOL                    fDoCache,
    W3_FILE_INFO **         ppFileInfo,
    FILE_CACHE_ASYNC_CONTEXT *pAsyncContext,
    BOOL                   *pfHandledSync,
    BOOL                    fAllowNoBuffering,
    BOOL                    fCheckForExistenceOnly
)
/*++

Routine Description:

    Returns a W3_FILE_INFO for the given file path.  Depending on fDoCache, 
    this W3_FILE_INFO will be cached

Arguments:

    strFileName - file name to find
    pDirmonConfig - Dir monitor config
    pOpeningUser - Token for user accessing the cache
    fDoCache - Set to TRUE if we should attempt to cache if possible
    ppFileInfo - Points to W3_FILE_INFO on success
    pAsyncContext - Provides the information necessary to notify the caller
                    when the file has been read when done async
    pfHandledSync - If provided, on return tells whether the open completed
                    synchronously
    fAllowNoBuffering - Allow the file to be opened with FILE_FLAG_NO_BUFFERING
    fCheckForExistenceOnly - If TRUE, ensure the file is accessible but do
                             not cache if it is not already cached

Return Value:

    HRESULT

--*/
{
    W3_FILE_INFO_KEY            fileKey;
    DIRMON_CONFIG               DefaultDirmonConfig;
    STACK_STRU(                 strParentDir, MAX_PATH );
    WCHAR *                     pszParentDir;
    W3_FILE_INFO *              pFileInfo;
    HRESULT                     hr;
    STACK_STRU(                 strFilePathKey, MAX_PATH );
    BOOL                        fShouldCacheHint = FALSE;
    BOOL                        fBufferFile = TRUE;

    if ( ppFileInfo == NULL || 
         pOpeningUser == NULL )
    {
        DBG_ASSERT( FALSE );
        return HRESULT_FROM_WIN32( ERROR_INVALID_PARAMETER );
    }

    //
    // Both of them should be null (for sync) or non-null (for async)
    //
    if ( ( pAsyncContext != NULL && pfHandledSync == NULL ) ||
         ( pAsyncContext == NULL && pfHandledSync != NULL ) )
    {
        DBG_ASSERT( FALSE );
        return HRESULT_FROM_WIN32( ERROR_INVALID_PARAMETER );
    }

    *ppFileInfo = NULL;

    //
    // We need to upper case the path to avoid a bunch of insensitive
    // compares in the hash table lookup
    //

    hr = strFilePathKey.Copy( strFileName );
    if ( FAILED( hr ) )
    {
        return hr;
    }
    _wcsupr( strFilePathKey.QueryStr() );

    //
    // If the cache is enabled, lookup there first
    //

    if ( QueryCacheEnabled() )
    {
        //
        // Make a key for the lookup
        //

        hr = fileKey.CreateCacheKey( strFilePathKey.QueryStr(),
                                     strFilePathKey.QueryCCH(),
                                     FALSE );
        if ( FAILED( hr ) )
        {
            return hr;
        }

        //
        // Look it up
        //

        hr = FindCacheEntry( &fileKey,
                             (CACHE_ENTRY **)&pFileInfo,
                             &fShouldCacheHint );
        if ( SUCCEEDED( hr ) )
        {
            BOOL fHasChanged = FALSE;
            DBG_ASSERT( pFileInfo != NULL );
            
            //
            // If it is a UNC file, we do not do dirmon but rather make sure
            // it has not changed on each open
            // Otherwise, we need to do an accesscheck against the current user
            //
            
            if ( !_fDoDirmonForUnc &&
                 ISUNC( strFilePathKey.QueryStr() ) &&
                 ( GetTickCount() - pFileInfo->QueryLastAttributeCheckTime() ) > 
                   _cmsecFileAttributeCheckThreshold )
            {
                hr = pFileInfo->CheckIfFileHasChanged( &fHasChanged,
                                                       pOpeningUser );
            }
            else
            {
                hr = pFileInfo->DoAccessCheck( pOpeningUser );
            }

            if ( FAILED( hr ) ) 
            {
                pFileInfo->DereferenceCacheEntry();
                return hr;
            }

            if ( !fHasChanged )
            {
                //
                // We have found a cached entry which we have access to.  
                // 
                // One more complication: If this file entry exists without
                // a handle/memory-buffer, then it is there for file 
                // existence purposes only.  If we're currently checking 
                // for existence only, then great!  If not, this entry is
                // bogus and we'll have to stuff in a new content entry
                //
                
                if ( pFileInfo->QueryFileBuffer() == NULL &&
                     pFileInfo->QueryFileHandle() == INVALID_HANDLE_VALUE && 
                     !fCheckForExistenceOnly )
                {
                    //
                    // We need a real cache entry.  Get rid of this entry
                    //
                    
                    FlushCacheEntry( pFileInfo->QueryCacheKey() );
                   
                    pFileInfo->DereferenceCacheEntry();
                    pFileInfo = NULL; 
                    
                    //
                    // Fall thru so that we try to cache it again 
                    // (this time completely).  
                    // 
                }
                else
                {
                    //
                    // We've satisfied the file cache request.  Return the
                    // descriptor
                    //
                    
                    *ppFileInfo = pFileInfo;
                    if ( pfHandledSync != NULL )
                    {
                        *pfHandledSync = TRUE;
                    }

                    return NO_ERROR;
                }
            }
            else
            {
                pFileInfo->DereferenceCacheEntry();
                pFileInfo = NULL;

                //
                // Release this entry but continue on to get a fresh one
                //
            }
        }
    }
    
    //
    // OK.  We have to open the file.  Figure out whether we should open the file 
    // buffered or not
    //

    if ( !QueryCacheEnabled() ||
         !fDoCache || 
         !fShouldCacheHint )
    {
        if ( fAllowNoBuffering )
        {
            fBufferFile = FALSE;
        }
    }

    //
    // We will simply open the file and return the object
    //

    pFileInfo = new W3_FILE_INFO( this );
    if ( pFileInfo == NULL )
    {
        return HRESULT_FROM_WIN32( GetLastError() );
    }

    //
    // Setup the cache key (in case we want to cache it)
    //

    hr = ((W3_FILE_INFO_KEY*) pFileInfo->QueryCacheKey())->CreateCacheKey( 
                                                     strFilePathKey.QueryStr(),
                                                     strFilePathKey.QueryCCH(),
                                                     TRUE );
    if ( FAILED( hr ) )
    {
        pFileInfo->DereferenceCacheEntry();
        return hr;
    }

    //
    // Open the file.  Note that we use the original strFileName 
    // parameter (which is not upper cased).  This is done to support
    // case sensitive file systems
    //

    hr = pFileInfo->OpenFile( strFileName,
                              pOpeningUser,
                              fBufferFile );
    if ( FAILED( hr ) )
    {
        pFileInfo->DereferenceCacheEntry();
        return hr;
    }

    //
    // If we aren't asked to cache the file, OR the file is not cacheable 
    // then we can return it now
    //

    if ( !QueryCacheEnabled() ||
         !fDoCache || 
         !fShouldCacheHint ||
         !pFileInfo->IsUlCacheable() )
    {
        *ppFileInfo = pFileInfo;
        if (pfHandledSync != NULL)
        {
            *pfHandledSync = TRUE;
        }

        return NO_ERROR;
    }

    pFileInfo->AllowUlCache();

    if ( !pFileInfo->IsCacheable() )
    {
        *ppFileInfo = pFileInfo;
        if ( pfHandledSync != NULL )
        {
            *pfHandledSync = TRUE;
        }

        return NO_ERROR;
    }
    
    //
    // In general, caching a file means dirmoning it.  The exception is if this is a UNC
    // file and we're configured to do file validation
    //

    if ( _fDoDirmonForUnc ||
         !ISUNC( strFilePathKey.QueryStr() ) )
    {
        //
        // If we're supposed to cache but no dirmon was configured, then just
        // assume the directory to monitor is the parent directory (and token
        // to use is NULL)
        //

        if ( pDirmonConfig == NULL )
        {
            DefaultDirmonConfig.hToken = NULL;
    
            pszParentDir = wcsrchr( strFilePathKey.QueryStr(), L'\\' );
            if ( pszParentDir != NULL )
            {
                hr = strParentDir.Copy( strFilePathKey.QueryStr(),
                                        DIFF( pszParentDir - strFilePathKey.QueryStr() ) );
                if ( SUCCEEDED( hr ) )
                {
                    DefaultDirmonConfig.pszDirPath = strParentDir.QueryStr();
                    pDirmonConfig = &DefaultDirmonConfig;
                }
            }
        }

        //
        // If we still don't have a dir mon configuration, then just don't cache
        //

        if ( pDirmonConfig == NULL )
        {
            *ppFileInfo = pFileInfo;
            if (pfHandledSync != NULL)
            {
                *pfHandledSync = TRUE;
            }

            return NO_ERROR;
        }

        //
        // Start monitoring the appropriate directory for changes
        //

        hr = pFileInfo->AddDirmonInvalidator( pDirmonConfig );
        if ( FAILED( hr ) )
        {
            //
            // If we can't monitor the directory, then just don't cache the item
            //

            *ppFileInfo = pFileInfo;
            if (pfHandledSync != NULL)
            {
                *pfHandledSync = TRUE;
            }

            return NO_ERROR;
        }
    }
        
    //
    // Attempt to cache the file.  Caching the file means reading the 
    // contents into memory, as well as caching the security descriptor
    //

    hr = pFileInfo->MakeCacheable( pOpeningUser,
                                   pAsyncContext,
                                   pfHandledSync,
                                   fCheckForExistenceOnly );
    if ( FAILED( hr ) )
    {
        *ppFileInfo = pFileInfo;
        if (pfHandledSync != NULL)
        {
            *pfHandledSync = TRUE;
        }

        return NO_ERROR;
    }    

    //
    // If an async read is pending, then return out now
    //

    if (pfHandledSync != NULL &&
        !*pfHandledSync)
    {
        *ppFileInfo = NULL;
        return NO_ERROR;
    }

    //
    // Insert into the hash table.  AddCacheEntry() will only error if
    // we cannot add the item, that is not fatal and we will simply return
    // this item and it will cleanup on dereference
    //
    
    AddCacheEntry( pFileInfo );
    
    *ppFileInfo = pFileInfo;
    
    return NO_ERROR;
}

HRESULT
W3_FILE_INFO_CACHE::Initialize(
    VOID
)
/*++

Routine Description:

    Initialize the file cache

Arguments:

    None

Return Value:

    HRESULT

--*/
{
    DWORD               dwError;
    DWORD               dwType;
    DWORD               dwValue;
    DWORD               cbData;
    DWORD               csecTTL = DEFAULT_W3_FILE_INFO_CACHE_TTL;
    DWORD               csecActivity = DEFAULT_W3_FILE_INFO_CACHE_ACTIVITY;
    HKEY                hKey = NULL;
    HRESULT             hr;
    CACHE_HINT_CONFIG   cacheHintConfig;
    
    //
    // Read the registry configuration of the file cache.
    // For now, that is just the legacy confiugration from IIS 5.x
    //
    
    dwError = RegOpenKeyEx( HKEY_LOCAL_MACHINE,
                            L"System\\CurrentControlSet\\Services\\inetinfo\\Parameters",
                            0,
                            KEY_READ,
                            &hKey );
    if ( dwError == ERROR_SUCCESS )
    {
        DBG_ASSERT( hKey != NULL );
    
        //
        // Should we be file caching at all?
        //
    
        cbData = sizeof( DWORD );
        dwError = RegQueryValueEx( hKey,
                                   L"DisableMemoryCache",
                                   NULL,
                                   &dwType,
                                   (LPBYTE) &dwValue,
                                   &cbData );
        if ( dwError == ERROR_SUCCESS && dwType == REG_DWORD )
        {
            _fEnableCache = dwValue ? FALSE : TRUE;
        }
        
        //
        // What is the biggest file we should cache in user mode?
        //
        
        cbData = sizeof( DWORD );
        dwError = RegQueryValueEx( hKey,
                                   L"MaxCachedFileSize",
                                   NULL,
                                   &dwType,
                                   (LPBYTE) &dwValue,
                                   &cbData );
        if ( dwError == ERROR_SUCCESS && dwType == REG_DWORD )
        {
            _cbFileSizeThreshold = dwValue;
        }
        
        //
        // What is the size of our memory cache?  Size is in MB
        //
        
        cbData = sizeof( DWORD );
        dwError = RegQueryValueEx( hKey,
                                   L"MemCacheSize",
                                   NULL,
                                   &dwType,
                                   (LPBYTE)&dwValue,
                                   &cbData );
        if ( dwError == ERROR_SUCCESS && dwType == REG_DWORD )
        {
            _cbMemoryCacheSize = dwValue * (1024 * 1024);
        }

        //
        // Read the maximum # of files in cache
        //
        
        cbData = sizeof( DWORD );
        dwError = RegQueryValueEx( hKey,
                                   L"MaxOpenFiles",
                                   NULL,
                                   &dwType,
                                   (LPBYTE) &dwValue,
                                   &cbData );
        if ( dwError == ERROR_SUCCESS && dwType == REG_DWORD )
        {
            _cMaxFileEntries = dwValue;
        }
        
        //
        // What is the TTL for the file cache?
        //

        cbData = sizeof( DWORD );
        dwError = RegQueryValueEx( hKey,
                                   L"ObjectCacheTTL",
                                   NULL,
                                   &dwType,
                                   (LPBYTE) &dwValue,
                                   &cbData );
        if ( dwError == ERROR_SUCCESS && dwType == REG_DWORD )
        {
            csecTTL = dwValue;
        }
        
        //
        // What is the activity period before putting into cache
        //
        
        cbData = sizeof( DWORD );
        dwError = RegQueryValueEx( hKey,
                                   L"ActivityPeriod",
                                   NULL,
                                   &dwType,
                                   (LPBYTE) &dwValue,
                                   &cbData );
        if ( dwError == ERROR_SUCCESS && dwType == REG_DWORD )
        {
            csecActivity = dwValue;
        }

        //
        // Do we do dirmonitoring for UNC's?
        //

        cbData = sizeof( DWORD );
        dwError = RegQueryValueEx( hKey,
                                   L"DoDirMonitoringForUnc",
                                   NULL,
                                   &dwType,
                                   (LPBYTE) &dwValue,
                                   &cbData );
        if ( dwError == ERROR_SUCCESS && dwType == REG_DWORD )
        {
            _fDoDirmonForUnc = dwValue;
        }
        
        //
        // What is the file attribute threshold time (for UNCs without dirmon)
        //
        
        cbData = sizeof( DWORD );
        dwError = RegQueryValueEx( hKey,
                                   L"FileAttributeCheckThreshold",
                                   NULL,
                                   &dwType,
                                   (LPBYTE) &dwValue,
                                   &cbData );
        if ( dwError == ERROR_SUCCESS && dwType == REG_DWORD )
        {
            _cmsecFileAttributeCheckThreshold = dwValue * 1000;
        }

        RegCloseKey( hKey );
    }
    
    //
    // Initialize memory cache
    //
    
    hr = InitializeMemoryCache();
    if ( FAILED( hr ) )
    {
        return hr;
    }
    
    //
    // Setup cache hint config (for now hardcoded)
    //
    
    if ( csecActivity != 0 )
    {
        cacheHintConfig.cmsecActivityWindow = csecActivity * 1000;
        cacheHintConfig.cmsecScavengeTime = cacheHintConfig.cmsecActivityWindow * 2;
        cacheHintConfig.cmsecTTL = cacheHintConfig.cmsecActivityWindow * 2;
    }

    //
    // We'll use TTL for scavenge period, and expect two inactive periods to
    // flush
    //
    
    hr = SetCacheConfiguration( csecTTL * 1000, 
                                csecTTL * 1000,
                                CACHE_INVALIDATION_DIRMON_FLUSH |
                                CACHE_INVALIDATION_DIRMON_SPECIFIC,
                                csecActivity ? &cacheHintConfig : NULL );
    if ( FAILED( hr ) )
    {
        TerminateMemoryCache();
        return hr;
    }
    
    //
    // Initialize file info lookaside
    //
    
    hr = W3_FILE_INFO::Initialize();
    if ( FAILED( hr ) )
    {
        TerminateMemoryCache();
    }
    
    return hr;
}    

VOID
W3_FILE_INFO_CACHE::Terminate(
    VOID
)
/*++

Routine Description:

    Terminate the file cache

Argument:

    None

Return Value:

    None

--*/
{
    TerminateMemoryCache();
    
    W3_FILE_INFO::Terminate();
}

VOID
W3_FILE_INFO_CACHE::DoDirmonInvalidationSpecific(
    WCHAR *             pszPath
)
/*++

Routine Description:

    Handle dirmon invalidation

Arguments:

    pszPath - Path which changed

Return Value:

    HRESULT

--*/
{
    HRESULT                 hr;
    W3_FILE_INFO_KEY        fileKey;
    
    DBG_ASSERT( pszPath != NULL );
    
    //
    // We're not flushing all, then just lookup given file and flush it
    //    
    
    hr = fileKey.CreateCacheKey( pszPath, 
                                 wcslen( pszPath ),
                                 FALSE );
    if ( SUCCEEDED( hr ) )
    {
        FlushCacheEntry( &fileKey );
    }
}

//static
W3_FILE_INFO_CACHE *
W3_FILE_INFO_CACHE::GetFileCache(
    VOID
)
{
    DBG_ASSERT( g_pW3Server != NULL );
    return g_pW3Server->QueryFileCache();
}

HRESULT
W3_FILE_INFO::CheckIfFileHasChanged(
    BOOL            *pfHasChanged,
    CACHE_USER      *pOpeningUser
)
/*++
    This function determines whether the file has changed for what is
    in the cache.  This is useful when we do not do directory change
    monitoring on UNC files.
--*/
{
    HRESULT hr = S_OK;
    BOOL fImpersonated = FALSE;

    //
    // We may need to impersonate some other user to open the file
    //

    if ( pOpeningUser->_hToken != NULL )
    {
        if ( !SetThreadToken( NULL, pOpeningUser->_hToken ) )
        {
            return HRESULT_FROM_WIN32( GetLastError() );
        }
        fImpersonated = TRUE;
    }

    //
    // Going to a UNC, let us bump up our thread count
    //
    ThreadPoolSetInfo( ThreadPoolIncMaxPoolThreads, 0 );

    WIN32_FILE_ATTRIBUTE_DATA fileData;

    if (!GetFileAttributesEx(_cacheKey._pszFileKey,
                             GetFileExInfoStandard,
                             &fileData))
    {
        hr = HRESULT_FROM_WIN32(GetLastError());
        goto Finished;
    }

    //
    // If the attributes, WriteTime, and if it is a file, size are same
    // then the file has not changed
    //
    if (fileData.dwFileAttributes == _dwFileAttributes &&
        *(__int64 *)&fileData.ftLastWriteTime == *(__int64 *)&_ftLastWriteTime &&
        ((fileData.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY) ||
         (fileData.nFileSizeHigh == _nFileSizeHigh &&
          fileData.nFileSizeLow == _nFileSizeLow)
        )
       )
    {
        *pfHasChanged = FALSE;
        _msLastAttributeCheckTime = GetTickCount();
    }
    else
    {
        *pfHasChanged = TRUE;
    }

 Finished:
    //
    // We are back, we can bump down the count again
    //
    ThreadPoolSetInfo( ThreadPoolDecMaxPoolThreads, 0 );

    if (fImpersonated)
    {
        DBG_REQUIRE(RevertToSelf());
    }

    return hr;
}

BOOL
W3_FILE_INFO::Checkout(
    CACHE_USER *pOpeningUser
)
{
    BOOL fHasChanged = FALSE;

    //
    // If it is a UNC file, we do not do dirmon but rather make sure
    // it has not changed on each open
    //
    if (!g_pW3Server->QueryFileCache()->QueryDoDirmonForUnc() &&
        ISUNC(_cacheKey._pszFileKey) &&
        ( GetTickCount() - QueryLastAttributeCheckTime() ) > 
          g_pW3Server->QueryFileCache()->QueryFileAttributeCheckThreshold() )
    {
        if (FAILED(CheckIfFileHasChanged(&fHasChanged,
                                         pOpeningUser)) ||
            fHasChanged)
        {
            return FALSE;
        }
    }

    return CACHE_ENTRY::Checkout(pOpeningUser);
}

// static
VOID CALLBACK W3_FILE_INFO::FileReadCompletion(
                            DWORD dwErrorCode,
                            DWORD dwNumberOfBytesTransfered,
                            LPOVERLAPPED lpOverlapped)
{
    FILE_CACHE_ASYNC_CONTEXT *pAsyncContext =
                            CONTAINING_RECORD(lpOverlapped,
                                              FILE_CACHE_ASYNC_CONTEXT,
                                              Overlapped);

    HRESULT hr = S_OK;

    if (dwErrorCode != 0)
    {
        hr = HRESULT_FROM_WIN32(dwErrorCode);
    }
    else
    {
        ULARGE_INTEGER liSize;
        W3_FILE_INFO *pFileInfo = pAsyncContext->pFileInfo;

        pFileInfo->QuerySize(&liSize);
        DBG_ASSERT(dwNumberOfBytesTransfered == liSize.QuadPart);

        CloseHandle(pFileInfo->_hFile);
        pFileInfo->_hFile = INVALID_HANDLE_VALUE;

        g_pW3Server->QueryFileCache()->AddCacheEntry( pFileInfo );
    }

    pAsyncContext->pfnCallback(pAsyncContext, hr);
}