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mkfs.c
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mkfs.c
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#include "mkfs.h"
#include "alloc.h"
#include "tests.h"
#include "dir_alloc.h"
//Emulates mounting a disk; allocates space in memory for the "hard drive" buffer
void mount()
{
_disk = (uint8_t *)malloc(sizeof(uint8_t) * (BLOCK_COUNT * BLOCK_SIZE));
memset(_disk, 0, sizeof(uint8_t) * (BLOCK_COUNT * BLOCK_SIZE));
}
//Builds the file system within the newly created disk. This includes:
//- Initializing the super block and confirming the endianness
//- Initializing the free list
//- Initializing the ilist
//- Claim the 0th data block to distinguish unallocated data block numbers in inodes
void mkfs() {
init_super_block();
init_free_list();
init_inode_list();
init_current_directory();
//Allocate the first data block as a "dummy block" to avoid confusion whether
//one of an inode's data blocks refers to data block 0 or is just unassigned
allocate_data_block();
//Allocate the first inode as the root diectory for the file system
allocate_root_inode();
}
//Initializes all of the super block values
void init_super_block() {
SBlock sblk = read_sblock(0);
uint32_t sblk_offset = 0;
uint8_t endian_l, endian_r;
//How many bits per byte
_spblk.bits_per_byte = BITS_PER_BYTE;
memcpy(&sblk.buffer[sblk_offset], &_spblk.bits_per_byte, sizeof(_spblk.bits_per_byte));
sblk_offset += sizeof(_spblk.bits_per_byte);
//How many bytes it takes to represent the largest block number
_spblk.block_number = BLOCK_NUMBER;
memcpy(&sblk.buffer[sblk_offset], &_spblk.block_number, sizeof(_spblk.block_number));
sblk_offset += sizeof(_spblk.block_number);
//Determine whether the underlying hardware is big-endian or little-endian checking against the block number
memcpy(&endian_l, &sblk.buffer[sblk_offset - sizeof(_spblk.block_number)], sizeof(endian_l));
memcpy(&endian_r, &sblk.buffer[sblk_offset - sizeof(_spblk.block_number) + (sizeof(_spblk.block_number) - 1)], sizeof(endian_r));
//Big-endian
if(endian_l == 0 && endian_r == _spblk.block_number)
{
_little_endian = 0;
}
//Little-endian
else
{
_little_endian = 1;
}
//Size of each addressable block
_spblk.block_size = BLOCK_SIZE;
memcpy(&sblk.buffer[sblk_offset], &_spblk.block_size, sizeof(_spblk.block_size));
sblk_offset += sizeof(_spblk.block_size);
//Size of each key-value pair for inode numbers-names
KeyVal kval;
_spblk.key_val_size += sizeof(kval.val);
_spblk.key_val_size += sizeof(kval.size);
_spblk.key_val_size += sizeof(kval.key);
memcpy(&sblk.buffer[sblk_offset], &_spblk.key_val_size, sizeof(_spblk.key_val_size));
sblk_offset += sizeof(_spblk.key_val_size);
//Total Number of blocks
_spblk.block_count = BLOCK_COUNT;
memcpy(&sblk.buffer[sblk_offset], &_spblk.block_count, sizeof(_spblk.block_count));
sblk_offset += sizeof(_spblk.block_count);
//Calculate the number of inode blocks
_spblk.inode_blk_count = (uint32_t)floor((double)_spblk.block_count * 0.1);
memcpy(&sblk.buffer[sblk_offset], &_spblk.inode_blk_count, sizeof(_spblk.inode_blk_count));
sblk_offset += sizeof(_spblk.inode_blk_count);
//Number of bytes to represent one inode
Inode node;
_spblk.inode_size += sizeof(node.i_number);
_spblk.inode_size += sizeof(node.d_blocks);
_spblk.inode_size += sizeof(node.fi_blocks);
_spblk.inode_size += sizeof(node.si_blocks);
_spblk.inode_size += sizeof(node.uid);
_spblk.inode_size += sizeof(node.gid);
_spblk.inode_size += sizeof(node.access_time);
_spblk.inode_size += sizeof(node.change_time);
_spblk.inode_size += sizeof(node.modify_time);
_spblk.inode_size += sizeof(node.file_size);
_spblk.inode_size += sizeof(node.permissions);
_spblk.inode_size += sizeof(node.link_count);
_spblk.inode_size += sizeof(node.f_type);
_spblk.inode_size += sizeof(node.f_large);
memcpy(&sblk.buffer[sblk_offset], &_spblk.inode_size, sizeof(_spblk.inode_size));
sblk_offset += sizeof(_spblk.inode_size);
//Total number of inodes; account for the byte-size of an inode
//not evenly fitting into the number of bytes in the inode list
_spblk.inode_count = (uint32_t)floor((double)(_spblk.inode_blk_count * BLOCK_SIZE) / _spblk.inode_size);
memcpy(&sblk.buffer[sblk_offset], &_spblk.inode_count, sizeof(_spblk.inode_count));
sblk_offset += sizeof(_spblk.inode_count);
//Calculate the number of blocks in the free inode list; take the ceil of each calculation
//to make sure there is enough space to represent all of the inodes
_spblk.free_inode_blk_count = (uint32_t)ceil((double)_spblk.inode_count / (_spblk.bits_per_byte * _spblk.block_size));
memcpy(&sblk.buffer[sblk_offset], &_spblk.free_inode_blk_count, sizeof(_spblk.free_inode_blk_count));
sblk_offset += sizeof(_spblk.free_inode_blk_count);
//Calculate the number of blocks in the free data block list; take the ceil of each calculation
//to make sure there is enough space to represent all of the data blocks
_spblk.free_data_blk_count = (uint32_t)ceil((double)(_spblk.block_count - (1 + _spblk.inode_blk_count + _spblk.free_inode_blk_count)) / (_spblk.bits_per_byte * _spblk.block_size));
memcpy(&sblk.buffer[sblk_offset], &_spblk.free_data_blk_count, sizeof(_spblk.free_data_blk_count));
sblk_offset += sizeof(_spblk.free_data_blk_count);
//Calculate the number of data blocks as the remainder of blocks
_spblk.data_blk_count = _spblk.block_count - (1 + _spblk.inode_blk_count + _spblk.free_inode_blk_count + _spblk.free_data_blk_count);
memcpy(&sblk.buffer[sblk_offset], &_spblk.data_blk_count, sizeof(_spblk.data_blk_count));
sblk_offset += sizeof(_spblk.data_blk_count);
//Offset to the list of free inode blocks
_spblk.free_inode_list_offset = 1;
memcpy(&sblk.buffer[sblk_offset], &_spblk.free_inode_list_offset, sizeof(_spblk.free_inode_list_offset));
sblk_offset += sizeof(_spblk.free_inode_list_offset);
//Offset to the list of free data blocks
_spblk.free_data_list_offset = _spblk.free_inode_list_offset + _spblk.free_inode_blk_count;
memcpy(&sblk.buffer[sblk_offset], &_spblk.free_data_list_offset, sizeof(_spblk.free_data_list_offset));
sblk_offset += sizeof(_spblk.free_data_list_offset);
//Offset to the inode list blocks
_spblk.inode_list_offset = _spblk.free_data_list_offset + _spblk.free_data_blk_count;
memcpy(&sblk.buffer[sblk_offset], &_spblk.inode_list_offset, sizeof(_spblk.inode_list_offset));
sblk_offset += sizeof(_spblk.inode_list_offset);
//Offset to the data list blocks
_spblk.data_list_offset = _spblk.inode_list_offset + _spblk.inode_blk_count;
memcpy(&sblk.buffer[sblk_offset], &_spblk.data_list_offset, sizeof(_spblk.data_list_offset));
sblk_offset += sizeof(_spblk.data_list_offset);
//Calculate the number of valid free inode list bytes
_spblk.free_inode_byte_count = (uint32_t)ceil((double)_spblk.inode_blk_count / _spblk.bits_per_byte);
memcpy(&sblk.buffer[sblk_offset], &_spblk.free_inode_byte_count, sizeof(_spblk.free_inode_byte_count));
sblk_offset += sizeof(_spblk.free_inode_byte_count);
//Calculate the number of valid free data list bytes
_spblk.free_data_byte_count = (uint32_t)ceil((double)_spblk.data_blk_count / _spblk.bits_per_byte);
memcpy(&sblk.buffer[sblk_offset], &_spblk.free_data_byte_count, sizeof(_spblk.free_data_byte_count));
sblk_offset += sizeof(_spblk.free_data_byte_count);
write_sblock(0, sblk);
}
//Setup the free lists so all flags are 1
void init_free_list()
{
uint32_t i;
for(i = _spblk.free_inode_list_offset; i < _spblk.free_inode_list_offset + _spblk.free_inode_blk_count + _spblk.free_data_blk_count; i++)
{
SBlock sblk = read_sblock(i);
memset(&sblk.buffer, 255, _spblk.block_size);
write_sblock(i, sblk);
}
}
//Sets up all of the inodes contiguously in memory
void init_inode_list()
{
Inode node;
uint32_t i, j, inode_num, dblk_offset;
inode_num = 0;
dblk_offset = 0;
//Increment over all of the inode list blocks
for(i = _spblk.inode_list_offset; i < _spblk.inode_list_offset + _spblk.inode_blk_count; i++)
{
//Read the ith and (i + 1)th blocks into dblk.buffer
DBlock dblk = read_dblock(i);
//Skip when writing the last inode block since it'll already be full and the dblk's
//second block is actually the first data block, don't want to write into it
if(i != _spblk.inode_list_offset + _spblk.inode_blk_count - 1)
{
//Make sure there is space to write only full inodes to the double block buffer
//by checking the current offset + the size of the inode you're about to write
while(dblk_offset + _spblk.inode_size < 2 * _spblk.block_size)
{
//Initialize the inode's values to default/null
node.i_number = inode_num;
memcpy(&dblk.buffer[dblk_offset], &node.i_number, sizeof(node.i_number));
dblk_offset += sizeof(node.i_number);
for(j = 0; j < D_BLOCKS; j++)
{
node.d_blocks[j] = 0;
memcpy(&dblk.buffer[dblk_offset], &node.d_blocks[j], sizeof(node.d_blocks[j]));
dblk_offset += sizeof(node.d_blocks[j]);
}
for(j = 0; j < FI_BLOCKS; j++)
{
node.fi_blocks[j] = 0;
memcpy(&dblk.buffer[dblk_offset], &node.fi_blocks[j], sizeof(node.fi_blocks[j]));
dblk_offset += sizeof(node.fi_blocks[j]);
}
for(j = 0; j < SI_BLOCKS; j++)
{
node.si_blocks[j] = 0;
memcpy(&dblk.buffer[dblk_offset], &node.si_blocks[j], sizeof(node.si_blocks[j]));
dblk_offset += sizeof(node.si_blocks[j]);
}
memset(node.uid, 0, 256);
memcpy(&dblk.buffer[dblk_offset], &node.uid, sizeof(node.uid));
dblk_offset += sizeof(node.uid);
memset(node.gid, 0, 256);
memcpy(&dblk.buffer[dblk_offset], &node.gid, sizeof(node.gid));
dblk_offset += sizeof(node.gid);
time(&node.access_time);
memcpy(&dblk.buffer[dblk_offset], &node.access_time, sizeof(node.access_time));
dblk_offset += sizeof(node.access_time);
time(&node.change_time);
memcpy(&dblk.buffer[dblk_offset], &node.change_time, sizeof(node.change_time));
dblk_offset += sizeof(node.change_time);
time(&node.modify_time);
memcpy(&dblk.buffer[dblk_offset], &node.modify_time, sizeof(node.modify_time));
dblk_offset += sizeof(node.modify_time);
node.file_size = 0;
memcpy(&dblk.buffer[dblk_offset], &node.file_size, sizeof(node.file_size));
dblk_offset += sizeof(node.file_size);
node.permissions = 777;
memcpy(&dblk.buffer[dblk_offset], &node.permissions, sizeof(node.permissions));
dblk_offset += sizeof(node.permissions);
node.link_count = 0;
memcpy(&dblk.buffer[dblk_offset], &node.link_count, sizeof(node.link_count));
dblk_offset += sizeof(node.link_count);
node.f_type = 0;
memcpy(&dblk.buffer[dblk_offset], &node.f_type, sizeof(node.f_type));
dblk_offset += sizeof(node.f_type);
node.f_large = 0;
memcpy(&dblk.buffer[dblk_offset], &node.f_large, sizeof(node.f_large));
dblk_offset += sizeof(node.f_large);
inode_num++;
}
//Write out the dblk; the next read will read back in the latter of the two blocks
//currently within dblk, that way it can fill the space at the end of it. Thus, with
//each write, you write one complete block and one incomplete block; the next time you
//read, you'll read back in the previously incomplete block, complete it, and fill the
//next block incompletely, repeating until you've reached the end
write_dblock(i, dblk);
//Start the next chunk of inode writes from the correct index in the latter block
dblk_offset -= _spblk.block_size;
}
}
}
void init_current_directory() {
_current_directory = (uint8_t *)malloc(sizeof(uint8_t) * MAX_PATH_LENGTH);
_parent_directory = (uint8_t *)malloc(sizeof(uint8_t) * MAX_PATH_LENGTH);
memset(_current_directory, 0, sizeof(uint8_t) * MAX_PATH_LENGTH);
memset(_parent_directory, 0, sizeof(uint8_t) * MAX_PATH_LENGTH);
strcpy((char*)_current_directory, "/");
strcpy((char*)_parent_directory, "/");
}
void allocate_root_inode() {
uint32_t inode_number = allocate_inode();
if(inode_number != 0) {
printf("Error, root inode must have i_number of zero\n");
}
writeCurrentAndPreviousDirectory(inode_number, inode_number);
}