BOOL PreReadClusterChain(RDWRHandle handle, CLUSTER start)
{
SECTOR firstsector;
char* ReadBuf;
struct Pipe pipe, *ppipe = &pipe;
unsigned char sectorspercluster;
unsigned BufSize;
if (!CacheActive()) return TRUE;
sectorspercluster = GetSectorsPerCluster(handle);
if (!sectorspercluster) return FALSE;
ReadBuf = AllocateReadBuf(MAX_ALLOCATING, &BufSize);
BufSize /= BYTESPERSECTOR;
pipe.buf = ReadBuf;
pipe.bufsize = BufSize;
pipe.index = 0;
pipe.maxindex = BufSize / sectorspercluster;
pipe.prevcluster = 0;
pipe.firstcluster = start;
if (!FileTraverseFat(handle, start, ClusterPreReader, (void**) &ppipe))
{
FreeReadBuf(ReadBuf);
return FALSE;
}
if (pipe.index)
{
firstsector = ConvertToDataSector(handle, pipe.firstcluster);
if (!firstsector)
{
FreeReadBuf(ReadBuf);
return FALSE;
}
if (ReadSectors(handle, pipe.index*sectorspercluster,
firstsector, pipe.buf) == -1)
{
FreeReadBuf(ReadBuf);
return FALSE;
}
}
FreeReadBuf(ReadBuf);
return TRUE;
}
CLUSTER GetNthFileCluster(RDWRHandle handle, CLUSTER firstclust, unsigned n,
BOOL* pasttheend)
{
struct Pipe pipe, *ppipe = &pipe;
pipe.n = n;
pipe.count = 0;
pipe.result = 1;
pipe.found = FALSE;
if (!FileTraverseFat(handle, firstclust, NthFileClusterFinder,
(void**)&ppipe))
RETURN_FTEERROR(FALSE);
*pasttheend = ((!pipe.found) && (n >= pipe.count));
return pipe.result;
}
