fsw_status_t fsw_alloc_zero(int len, void **ptr_out)
{
fsw_status_t status;
status = fsw_alloc(len, ptr_out);
if (status)
return status;
fsw_memzero(*ptr_out, len);
return FSW_SUCCESS;
}
fsw_status_t fsw_shandle_read(struct fsw_shandle *shand, fsw_u32 *buffer_size_inout, void *buffer_in)
{
fsw_status_t status;
struct fsw_dnode *dno = shand->dnode;
struct fsw_volume *vol = dno->vol;
fsw_u8 *buffer, *block_buffer;
fsw_u32 buflen, copylen, pos;
fsw_u32 log_bno, pos_in_extent, phys_bno, pos_in_physblock;
fsw_u32 cache_level;
if (shand->pos >= dno->size) { // already at EOF
*buffer_size_inout = 0;
return FSW_SUCCESS;
}
// initialize vars
buffer = buffer_in;
buflen = *buffer_size_inout;
pos = (fsw_u32)shand->pos;
cache_level = (dno->type != FSW_DNODE_TYPE_FILE) ? 1 : 0;
// restrict read to file size
if (buflen > dno->size - pos)
buflen = (fsw_u32)(dno->size - pos);
while (buflen > 0) {
// get extent for the current logical block
log_bno = pos / vol->log_blocksize;
if (shand->extent.type == FSW_EXTENT_TYPE_INVALID ||
log_bno < shand->extent.log_start ||
log_bno >= shand->extent.log_start + shand->extent.log_count) {
if (shand->extent.type == FSW_EXTENT_TYPE_BUFFER)
fsw_free(shand->extent.buffer);
// ask the file system for the proper extent
shand->extent.log_start = log_bno;
status = vol->fstype_table->get_extent(vol, dno, &shand->extent);
if (status) {
shand->extent.type = FSW_EXTENT_TYPE_INVALID;
return status;
}
}
pos_in_extent = pos - shand->extent.log_start * vol->log_blocksize;
// dispatch by extent type
if (shand->extent.type == FSW_EXTENT_TYPE_PHYSBLOCK) {
// convert to physical block number and offset
phys_bno = shand->extent.phys_start + pos_in_extent / vol->phys_blocksize;
pos_in_physblock = pos_in_extent & (vol->phys_blocksize - 1);
copylen = vol->phys_blocksize - pos_in_physblock;
if (copylen > buflen)
copylen = buflen;
// get one physical block
status = fsw_block_get(vol, phys_bno, cache_level, (void **)&block_buffer);
if (status)
return status;
// copy data from it
fsw_memcpy(buffer, block_buffer + pos_in_physblock, copylen);
fsw_block_release(vol, phys_bno, block_buffer);
} else if (shand->extent.type == FSW_EXTENT_TYPE_BUFFER) {
copylen = shand->extent.log_count * vol->log_blocksize - pos_in_extent;
if (copylen > buflen)
copylen = buflen;
fsw_memcpy(buffer, (fsw_u8 *)shand->extent.buffer + pos_in_extent, copylen);
} else { // _SPARSE or _INVALID
copylen = shand->extent.log_count * vol->log_blocksize - pos_in_extent;
if (copylen > buflen)
copylen = buflen;
fsw_memzero(buffer, copylen);
}
buffer += copylen;
buflen -= copylen;
pos += copylen;
}
*buffer_size_inout = (fsw_u32)(pos - shand->pos);
shand->pos = pos;
return FSW_SUCCESS;
}
