/* if offset is bigger than file_length, allocate new disk and update inode */
bool inode_update_file_length(struct inode_disk *inode_disk, off_t start_pos, off_t end_pos)
{
off_t size = end_pos - start_pos;
off_t offset = start_pos;
void *zeros = malloc(SECTOR_SIZE);
int chunck_size;
/* make zeros */
if(zeros == NULL)
return false;
memset(zeros, 0, SECTOR_SIZE);
while( size > 0 )
{
/* offset in the disk block */
int sector_ofs = offset % SECTOR_SIZE;
/* caculate chunck size */
if( size >= SECTOR_SIZE)
chunck_size = SECTOR_SIZE - sector_ofs;
else
{
if(sector_ofs + size > SECTOR_SIZE)
chunck_size = SECTOR_SIZE - sector_ofs;
else
chunck_size = size;
}
/* if sector_ofs is bigger than zero, already allocate disk block */
if(sector_ofs > 0 )
{
}
/* allocate new disk block */
else
{
struct sector_location sec_loc;
block_sector_t sector_idx;
/* allocate new disk block */
if(free_map_allocate(1, §or_idx) == true)
{
/* update disk block number */
locate_byte(offset, &sec_loc);
register_sector(inode_disk, sector_idx, sec_loc);
}
else
{
free(zeros);
return false;
}
/* init new disk block to 0 */
bc_write(sector_idx, zeros, 0, SECTOR_SIZE, 0);
}
/* advance */
size -= chunck_size;
offset += chunck_size;
}
free(zeros);
return true;
}
int
write(int fd, char *buf, int size)
{
return (bc_write(fd, buf, size));
}
/* update new disk block number to inode_disk */
static bool register_sector(struct inode_disk *inode_disk, block_sector_t new_sector, struct sector_location sec_loc)
{
switch(sec_loc.directness)
{
case NORMAL_DIRECT:
/* update new disk block */
inode_disk->direct_map_table[sec_loc.index1] = new_sector;
break;
case INDIRECT:
/* if use indirect first, allocate disk for indirect index block */
if(sec_loc.index1 == 0)
{
block_sector_t sector_idx;
if(free_map_allocate(1, §or_idx))
inode_disk->indirect_block_sec = sector_idx;
}
/* allocate new_block and write new_sector to new_block */
block_sector_t *new_block = (block_sector_t *)malloc(SECTOR_SIZE);
if(new_block == NULL)
return false;
new_block[sec_loc.index1] = new_sector;
/* write new_block to index block */
bc_write(inode_disk->indirect_block_sec, (void *)new_block,map_table_offset(sec_loc.index1) ,4 ,map_table_offset(sec_loc.index1));
free(new_block);
break;
case DOUBLE_INDIRECT:
/* if index1 and index2 is 0, allocate disk for index block 1 */
if(sec_loc.index1 == 0 && sec_loc.index2 ==0)
{
block_sector_t sector_idx;
if(free_map_allocate(1, §or_idx))
inode_disk->double_indirect_block_sec = sector_idx;
}
/* if index2 is 0, allocate disk for index block 2 and update index block 1 */
if(sec_loc.index2 == 0 )
{
/* allocate disk for index block 2 */
block_sector_t sector_idx;
if(free_map_allocate(1, §or_idx) == false)
return false;
/* update index block 1*/
block_sector_t *new_block = (block_sector_t *)malloc(SECTOR_SIZE);
if(new_block == NULL)
return false;
new_block[sec_loc.index1] = sector_idx;
bc_write(inode_disk->double_indirect_block_sec, (void *)new_block, sec_loc.index1 * 4, 4, sec_loc.index1 * 4);
free(new_block);
}
/* update index block 2 */
/* Value for read index_block 1 */
block_sector_t *index_block1 = (block_sector_t *)malloc(SECTOR_SIZE);
if(index_block1 == NULL)
return false;
/* Value for update index_block 2 */
block_sector_t *new_block2 = (block_sector_t *)malloc(SECTOR_SIZE);
if(new_block2 == NULL)
return false;
/* read index block 1 */
bc_read(inode_disk->double_indirect_block_sec, (void *)index_block1, 0, SECTOR_SIZE, 0);
block_sector_t block_sector = index_block1[sec_loc.index1];
/* update index block 2*/
new_block2[sec_loc.index2] = new_sector;
bc_write(block_sector, (void *)new_block2, sec_loc.index2 * 4, 4, sec_loc.index2 * 4);
free(new_block2);
free(index_block1);
break;
default:
return false;
}
return true;
}
