* Copyright 2011, Haiku Inc. All rights reserved.
* This file may be used under the terms of the MIT License.
*
* Authors:
* Jérôme Duval
*/
#include "DataStream.h"
#include "Volume.h"
#ifdef TRACE_EXFAT
# define TRACE(x...) dprintf("\33[34mexfat:\33[0m " x)
#else
# define TRACE(x...) ;
#endif
#define ERROR(x...) dprintf("\33[34mexfat:\33[0m " x)
DataStream::DataStream(Volume* volume, Inode* inode, off_t size)
:
kBlockSize(volume->BlockSize()),
kClusterSize(volume->ClusterSize()),
fVolume(volume),
fInode(inode),
fSize(size)
{
fNumBlocks = size == 0 ? 0 : ((size - 1) / kBlockSize) + 1;
}
DataStream::~DataStream()
{
}
status_t
DataStream::FindBlock(off_t pos, off_t& physical, off_t *_length)
{
if (pos >= fSize) {
TRACE("FindBlock: offset larger than size\n");
return B_ENTRY_NOT_FOUND;
}
cluster_t clusterIndex = pos / kClusterSize;
uint32 offset = pos % kClusterSize;
cluster_t cluster = fInode->StartCluster();
for (uint32 i = 0; i < clusterIndex; i++)
cluster = fInode->NextCluster(cluster);
fsblock_t block;
if (fVolume->ClusterToBlock(cluster, block) != B_OK)
return B_BAD_DATA;
physical = block * kBlockSize + offset;
for (uint32 i = 0; i < 64; i++) {
cluster_t extentEnd = fInode->NextCluster(cluster);
if (extentEnd == EXFAT_CLUSTER_END || extentEnd == cluster + 1)
break;
cluster = extentEnd;
}
*_length = min_c((cluster - clusterIndex + 1) * kClusterSize - offset,
fSize - pos);
TRACE("inode %" B_PRIdINO ": cluster %" B_PRIu32 ", pos %" B_PRIdOFF ", %"
B_PRIdOFF "\n", fInode->ID(), clusterIndex, pos, physical);
return B_OK;
}
