int get_blk_pointer(blk_pointers_t* pointers, int blknum)
{
int indirect_pointers[BLKSIZ/BLKPOINTERSIZ];
// If blk num is for a direct pointer
if(blknum < NUMDIRECTPOINTERS) {
if(pointers->direct[blknum] == 0) {
if( (pointers->direct[blknum] = get_free_datablock()) == 0) return -1;
}
return pointers->direct[blknum];
}
// If block num is the first indirect pointer entry
if(pointers->indirect == 0) {
if( (pointers->indirect = get_free_datablock()) == 0) return -1;
memset(indirect_pointers, 0, BLKSIZ);
write_blocks(pointers->indirect, 1, (void*)indirect_pointers);
}
// If block num is an indirect pointer entry that is not the first
read_blocks(pointers->indirect, 1, (void*)indirect_pointers);
if(indirect_pointers[blknum - NUMDIRECTPOINTERS] == 0) {
if( (indirect_pointers[blknum - NUMDIRECTPOINTERS] = get_free_datablock()) == 0) return -1;
write_blocks(pointers->indirect, 1, (void*)indirect_pointers);
}
return indirect_pointers[blknum - NUMDIRECTPOINTERS];
}
int add_data_block(int inode_num)
{
struct datablock *dblock = malloc(sizeof(struct datablock));
struct indirection_block *iblock1;
struct indirection_block *iblock2;
struct inode_block *iblock;
struct inode *inode;
int block_num;
int new_db_num = get_free_datablock();
DEBUG1 && printf("new db number: %d \n", new_db_num);
if(new_db_num < 0)
return -1;
get_inode(&iblock, &inode, inode_num);
block_num = inode->num_blocks;
if(!inode)
{
DEBUG2 && printf("inode is null\n");
return -1;
}
if(block_num >= 0 && block_num < 10)
{
inode->file_blocks[block_num] = new_db_num;
inode->num_blocks++;
if(put_inode_block(iblock, inode_num))
{
return -1;
}
free(iblock);
return new_db_num;
}
else if(block_num == 10)
{
//make indirection block
struct indirection_block *ib = malloc(sizeof(struct indirection_block));
ib->pointer[0] = new_db_num;
int ind_block_num = get_free_datablock();
if(ind_block_num < 0)
return -1;
DEBUG1 && printf("adding indirection block: %d\n", ind_block_num);
if(!write_block(file, ib, ind_block_num))
{
DEBUG2 && printf("Error writing indirection block\n");
return -1;
}
inode->indirect1 = ind_block_num;
inode->num_blocks++;
if(put_inode_block(iblock, inode_num))
{
return -1;
}
free(ib);
free(iblock);
return new_db_num;
}
else if(block_num > 10 && block_num < (10+128))
{
struct indirection_block *ib = malloc(sizeof(struct indirection_block));
int ind_block_num = inode->indirect1;
if(!read_block(file, ib, ind_block_num))
{
DEBUG2 && printf("Error reading indirection block\n");
return -1;
}
ib->pointer[block_num - 10] = new_db_num;
if(! write_block(file, ib, ind_block_num))
{
DEBUG2 && printf("Error writing indirection block\n");
return -1;
}
inode->num_blocks++;
if(put_inode_block(iblock, inode_num))
{
return -1;
}
free(ib);
free(iblock);
return new_db_num;
}
else if(block_num == (10+128))
{
struct indirection_block *ib1 = malloc(sizeof(struct indirection_block));
struct indirection_block *ib2 = malloc(sizeof(struct indirection_block));
int ind_block_num1 = get_free_datablock();
int ind_block_num2 = get_free_datablock();
if(ind_block_num1 < 0 || ind_block_num2 < 0)
return -1;
inode->indirect2 = ind_block_num1;
inode->num_blocks++;
ib1->pointer[0] = ind_block_num2;
ib2->pointer[0] = new_db_num;
if(!write_block(file, ib1, ind_block_num1))
{
DEBUG2 && printf("Error writing indirection block\n");
return -1;
}
if(!write_block(file, ib2, ind_block_num2))
{
DEBUG2 && printf("Error writing indirection block\n");
return -1;
}
if(put_inode_block(iblock, inode_num))
{
return -1;
}
free(ib1);
free(ib2);
free(iblock);
return new_db_num;
}
else if(block_num > (10+128) && block_num < (10+128+(128*128)))
{
struct indirection_block *ib1 = malloc(sizeof(struct indirection_block));
struct indirection_block *ib2 = malloc(sizeof(struct indirection_block));
int ind_block_num1 = inode->indirect2;
if( !read_block(file, ib1, ind_block_num1))
{
DEBUG2 && printf("error reading datablock\n");
return -1;
}
if(((block_num - (10+128)) % 128) == 0)
{
int new_ind_block = get_free_datablock();
ib1->pointer[(block_num - (10+128)) / 128] = new_ind_block;
ib2->pointer[0] = new_db_num;
inode->num_blocks++;
if(!write_block(file, ib1, ind_block_num1))
{
DEBUG2 && printf("error reading datablock\n");
return -1;
}
if(!write_block(file, ib2, new_ind_block))
{
DEBUG2 && printf("error reading datablock\n");
return -1;
}
if(put_inode_block(iblock, inode_num))
{
return -1;
}
return new_db_num;
}
else
{
int ind_block_num2 = ib1->pointer[(block_num - (10+128)) / 128];
if(!read_block(file, ib2, ind_block_num2))
{
DEBUG2 && printf("error reading datablock\n");
return -1;
}
ib2->pointer[(block_num - (10+128)) % 128] = new_db_num;
inode->num_blocks++;
if( !write_block(file, ib2, ind_block_num2))
{
DEBUG2 && printf("error reading datablock\n");
return -1;
}
if(put_inode_block(iblock, inode_num))
{
return -1;
}
return new_db_num;
}
}
else
{
DEBUG2 && printf("Error: cannot add another block, filesize max reached\n");
return -1;
}
return new_db_num;
}
