int DfsInodeReadBytes(int handle, void *mem, int start_byte, int num_bytes) {
int i;
int end_byte = start_byte+num_bytes-1;
int byte_start,byte_end;
int block_start,block_end;
dfs_block block;
int blocknum;
int byte_read;
// printf("In DfsInodeReadBytes\n");
if(sb.valid == 0){
printf("File system not open!\n");
return DFS_FAIL;
}
if((handle<0)||(handle>DFS_INODE_MAX_NUM)){
printf("Invalid inode handle = %d\n",handle);
return DFS_FAIL;
}
if(inodes[handle].inuse == 0){
printf("Inode not allocated!\n");
return DFS_FAIL;
}
if((start_byte<0)||(num_bytes<0)||((end_byte)>inodes[handle].filesize)){
printf("Invalid start_byte = %d or num_byte= %d\n",start_byte,num_bytes);
return DFS_FAIL;
}
block_start = (start_byte/sb.filesys_blocksize);
byte_start = (start_byte%sb.filesys_blocksize);
block_end = (end_byte/sb.filesys_blocksize);
byte_end = (end_byte%sb.filesys_blocksize);
if(block_start == block_end){
blocknum = DfsInodeTranslateVirtualToFilesys(handle,block_start);
// printf("read from block(start=end) %d\n",blocknum);
DfsReadBlock(blocknum,&block);
bcopy((char *)((int)&block+byte_start),(char *)mem,num_bytes);
return (num_bytes);
}
else{
blocknum = DfsInodeTranslateVirtualToFilesys(handle,block_start);
// printf("read from block(1st) %d\n",blocknum);
DfsReadBlock(blocknum,&block);
byte_read = sb.filesys_blocksize-(byte_start);
bcopy((char *)((int)&block+byte_start),(char *)mem,byte_read);
for(i=(block_start)+1;i<(block_end);i++){
blocknum = DfsInodeTranslateVirtualToFilesys(handle,i);
// printf("read from block(middle) %d\n",blocknum);
DfsReadBlock(blocknum,&block);
bcopy((char *)(&block),(char *)((int)mem+byte_read),sb.filesys_blocksize);
byte_read +=sb.filesys_blocksize;
}
blocknum = DfsInodeTranslateVirtualToFilesys(handle,block_end);
// printf("read from block(last) %d\n",blocknum);
DfsReadBlock(blocknum,&block);
bcopy((char *)(&block),(char *)((int)mem+byte_read),(byte_end)+1);
byte_read +=(byte_end)+1;
return (byte_read);
}
}
int DfsOpenFileSystem() {
disk_block diskb;
dfs_block dfsb;
char* inbytes;
unsigned int i;
//Basic steps:
// Check that filesystem is not already open
if(sb.valid) {
printf("DfsOpenFilesystem: File system is already open\n");
return DFS_FAIL;
}
// Read superblock from disk. Note this is using the disk read rather
// than the DFS read function because the DFS read requires a valid
// filesystem in memory already, and the filesystem cannot be valid
// until we read the superblock. Also, we don't know the block size
// until we read the superblock, either.
DiskReadBlock(1, &diskb);
// Copy the data from the block we just read into the superblock in memory
bcopy(diskb.data, (char*) &sb, sizeof(sb));
// sb should be valid at this point since sb was supposed to be valid on disk
if(!sb.valid) {
printf("DfsOpenFileSystem: Filesystem on disk is not valid\n");
return DFS_FAIL;
}
// All other blocks are sized by virtual block size:
// Read inodes
inbytes = (char*) inodes;
for(i = sb.inode_start_block; i < sb.fbv_start_block; i++) {
DfsReadBlock(i, &dfsb);
bcopy(dfsb.data, &(inbytes[(i - sb.inode_start_block) * sb.blocksize]), sb.blocksize);
}
// Read free block vector
inbytes = (char*) fbv;
for(i = sb.fbv_start_block; i < sb.data_start_block; i++) {
DfsReadBlock(i, &dfsb);
bcopy(dfsb.data, &(inbytes[(i - sb.fbv_start_block) * sb.blocksize]), sb.blocksize);
}
// Change superblock to be invalid, write back to disk, then change
// it back to be valid in memory
sb.valid = 0;
bzero(diskb.data, DISK_BLOCKSIZE);
bcopy((char*)&sb, diskb.data, sizeof(sb));
DiskWriteBlock(1, &diskb);
sb.valid = 1;
return DFS_SUCCESS;
}
int DfsInodeAllocateVirtualBlock(int handle, int virtual_blocknum) {
dfs_block indirect_table;
int blocknum;
uint32 *table;
// printf("In DfsInodeAllocateVirtualBlock\n");
if (sb.valid == 0){
printf("File system not opened\n");
return DFS_FAIL;
}
if((handle<0)||(handle>DFS_INODE_MAX_NUM)){
printf("Invalid inode handle = %d\n",handle);
return DFS_FAIL;
}
if(inodes[handle].inuse == 0){
printf("Inode not allocated!\n");
return DFS_FAIL;
}
if((virtual_blocknum<0)||(virtual_blocknum>(sb.filesys_blocksize/sizeof(uint32)+10))){
printf("Invalid virtural_blocknum = %d\n",virtual_blocknum);
return DFS_FAIL;
}
//check direct or indirect
if(virtual_blocknum < 10){
if((blocknum = DfsAllocateBlock()) == DFS_FAIL){
printf("Cannot allocate block for direct table\n");
return DFS_FAIL;
}
inodes[handle].direct[virtual_blocknum] =(uint32)blocknum;
return blocknum;
}
else{
table =(uint32 *)(&indirect_table);
if((inodes[handle].indirect)!=0){
DfsReadBlock(inodes[handle].indirect,(dfs_block *)table);
if((blocknum = DfsAllocateBlock()) == DFS_FAIL){
printf("Cannot allocate block for direct table\n");
return DFS_FAIL;
}
table[virtual_blocknum-10] =(uint32)blocknum;
DfsWriteBlock(inodes[handle].indirect,(dfs_block *)table);
return blocknum;
}
else{
if((blocknum = DfsAllocateBlock()) == DFS_FAIL){
printf("Cannot allocate block for indirect table\n");
return DFS_FAIL;
}
inodes[handle].indirect = (uint32)blocknum;
bzero((char *)table,sb.filesys_blocksize);
if((blocknum = DfsAllocateBlock()) == DFS_FAIL){
printf("Cannot allocate block for indirect address\n");
return DFS_FAIL;
}
table[virtual_blocknum-10] = (uint32)blocknum;
DfsWriteBlock(inodes[handle].indirect,(dfs_block *)table);
return blocknum;
}
}
}
int DfsInodeDelete(int handle) {
int i;
dfs_block indirect_table;
uint32 *table;
// printf("In DfsInodeDelete\n");
if (sb.valid == 0){
printf("File system not open!\n");
return DFS_FAIL;
}
if((handle<0)||(handle>DFS_INODE_MAX_NUM)){
printf("Invalid inode handle = %d\n",handle);
return DFS_FAIL;
}
if(inodes[handle].inuse == 0){
printf("Inode not allocated!\n");
return DFS_FAIL;
}
LockHandleAcquire(lock_inode);
//Free direct table then check if there is indirect address
for(i=0;i<10;i++){
if(inodes[handle].direct[i]!=0){
if(DfsFreeBlock((int)inodes[handle].direct[i])==DFS_FAIL){
printf("Cannot free blocks in direct table!\n");
return DFS_FAIL;
}
inodes[handle].direct[i]=0;
}
}
//Free the indirect table
if(inodes[handle].indirect != 0){
table =(uint32 *)(&indirect_table);
DfsReadBlock(inodes[handle].indirect,&indirect_table);
for(i=0;i<(sb.filesys_blocksize)/sizeof(uint32);i++){
if(table[i]!=0){
if (DfsFreeBlock((int)table[i])== DFS_FAIL){
printf("Cannot free blocks in indirect table\n");
return DFS_FAIL;
}
}
}
if(DfsFreeBlock((int)inodes[handle].indirect)==DFS_FAIL){
printf("Cannot free blocks in indirect table\n");
}
inodes[handle].indirect=0;
}
FreeEntry(handle);
inodes[handle].filesize = 0;
// for(i=0;i< FILENAME_LENGTH;i++){
// inodes[handle].filename[i]='\0';
// }
inodes[handle].permission = 0;
inodes[handle].type = 0;
inodes[handle].ownerid = 0;
inodes[handle].inuse = 0;
LockHandleRelease(lock_inode);
return DFS_SUCCESS;
}
//-----------------------------------------------------------------
// DfsInodeTranslateVirtualToFilesys translates the
// virtual_blocknum to the corresponding file system block using
// the inode identified by handle. Return DFS_FAIL on failure.
//-----------------------------------------------------------------
uint32 DfsInodeTranslateVirtualToFilesys(uint32 handle, uint32 virtual_blocknum) {
dfs_block dfsb;
int* block_entry_table;
if(!sb.valid) {
printf("DfsInodeTranslateVirtualToFilesys: invalid file system\n");
return DFS_FAIL;
}
if(!inodes[handle].valid) {
printf("DfsInodeTranslateVirtualToFilesys: invalid inode\n");
return DFS_FAIL;
}
if(virtual_blocknum >= 10) {
block_entry_table = (int*) dfsb.data;
if(!DFS_IS_BLOCK_ENTRY_VALID(inodes[handle].indir_block_entry)) {
printf("DfsInodeTranslateVirtualToFilesys: invalid block entry in indirect blocks %d\n", virtual_blocknum);
return DFS_FAIL;
}
DfsReadBlock(DFS_GET_BLOCK_NUM(inodes[handle].indir_block_entry), &dfsb);
virtual_blocknum -= 10;
if(DFS_IS_BLOCK_ENTRY_VALID(block_entry_table[virtual_blocknum])) {
return DFS_GET_BLOCK_NUM(block_entry_table[virtual_blocknum]);
}
else {
printf("DfsInodeTranslateVirtualToFilesys: invalid block's block entry in indirect blocks %d\n", virtual_blocknum);
return DFS_FAIL;
}
}
else {
block_entry_table = inodes[handle].direct_block_entries;
if(DFS_IS_BLOCK_ENTRY_VALID(block_entry_table[virtual_blocknum])) {
return DFS_GET_BLOCK_NUM(block_entry_table[virtual_blocknum]);
}
else {
printf("DfsInodeTranslateVirtualToFilesys: invalid block entry in direct blocks %d\n", virtual_blocknum);
return DFS_FAIL;
}
}
printf("---THIS SHOULD NOT HAPPEN---\n");
return DFS_FAIL;
}
int DfsInodeTranslateVirtualToFilesys(int handle, int virtual_blocknum) {
dfs_block indirect_table;
uint32 *table;
uint32 blocknum;
// printf("In DfsInodeTranslateVirtualToFilesys\n");
if (sb.valid == 0){
printf("File system not opened\n");
return DFS_FAIL;
}
if((handle<0)||(handle>DFS_INODE_MAX_NUM)){
printf("Invalid inode handle = %d\n",handle);
return DFS_FAIL;
}
if(inodes[handle].inuse == 0){
printf("Inode not allocated!\n");
return DFS_FAIL;
}
if((virtual_blocknum<0)||(virtual_blocknum>(sb.filesys_blocksize/sizeof(uint32)+10))){
printf("Invalid virtural_blocknum = %d\n",virtual_blocknum);
return DFS_FAIL;
}
//check direct or indirect
if(virtual_blocknum<10){
return (inodes[handle].direct[virtual_blocknum]);
}
else{
if(inodes[handle].indirect == 0){
printf("Indirect address table not exist!\n");
return DFS_FAIL;
}
else{
table = (uint32 *)(&indirect_table);
DfsReadBlock(inodes[handle].indirect,&indirect_table);
blocknum = table[virtual_blocknum-10];
return (int)blocknum;
}
}
return DFS_FAIL;
}
int DfsInodeTruncateFile(uint32 handle) {
int i;
dfs_block dfsb;
int* inints = (int*) dfsb.data;
if(!sb.valid) {
printf("DfsInodeTruncateFile: invalid file system\n");
return DFS_FAIL;
}
if(!inodes[handle].valid) {
printf("DfsInodeTruncateFile: invalid inode\n");
return DFS_FAIL;
}
while(LockHandleAcquire(dfs_fbv_lock) != SYNC_SUCCESS);
if(DFS_IS_BLOCK_ENTRY_VALID(inodes[handle].indir_block_entry)) {
DfsReadBlock(DFS_GET_BLOCK_NUM(inodes[handle].indir_block_entry), &dfsb);
for(i = 0; i < (sb.blocksize / sizeof(int)); i++) {
if(DFS_IS_BLOCK_ENTRY_VALID(inints[i])) {
SetFreeVector(DFS_GET_BLOCK_NUM(inints[i]), 1);
}
}
// clear out the indirect block entry table
bzero(dfsb.data, sb.blocksize);
DfsWriteBlock(DFS_GET_BLOCK_NUM(inodes[handle].indir_block_entry), &dfsb);
SetFreeVector(DFS_GET_BLOCK_NUM(inodes[handle].indir_block_entry), 1);
inodes[handle].indir_block_entry = DFS_SET_BLOCK_ENTRY(0, 0);
}
for(i = 0; i < 10; i++) {
if(DFS_IS_BLOCK_ENTRY_VALID(inodes[handle].direct_block_entries[i])) {
SetFreeVector(DFS_GET_BLOCK_NUM(inodes[handle].direct_block_entries[i]), 1);
inodes[handle].direct_block_entries[i] = DFS_SET_BLOCK_ENTRY(0, 0);
}
}
LockHandleRelease(dfs_fbv_lock);
inodes[handle].filesize = 0;
return DFS_SUCCESS;
}
//-----------------------------------------------------------------
// DfsInodeWriteBytes writes num_bytes from the memory pointed to
// by mem to the file represented by the inode handle, starting at
// virtual byte start_byte. Note that if you are only writing part
// of a given file system block, you'll need to read that block
// from the disk first. Return DFS_FAIL on failure and the number
// of bytes written on success.
//-----------------------------------------------------------------
int DfsAllocateCheck(int handle,int blocknum){
uint32 *table;
dfs_block indirect_table;
if(blocknum<10){
if(inodes[handle].direct[blocknum]==0){
return DFS_FAIL;
}
}
else{
if(inodes[handle].indirect==0){
return DFS_FAIL;
}
else{
table =(uint32 *)(&indirect_table);
DfsReadBlock(inodes[handle].indirect,&indirect_table);
if(table[blocknum-10]==0){
return DFS_FAIL;
}
}
}
return DFS_SUCCESS;
}
//-----------------------------------------------------------------
// DfsInodeReadBytes reads num_bytes from the file represented by
// the inode handle, starting at virtual byte start_byte, copying
// the data to the address pointed to by mem. Return DFS_FAIL on
// failure, and the number of bytes read on success.
//-----------------------------------------------------------------
int DfsInodeReadBytes(uint32 handle, void *mem, int start_byte, int num_bytes) {
int cur_byte = start_byte;
int blocknum;
int data_bytes;
int byte_count = 0;
dfs_block dfsb;
char* mem_bytes = (char*) mem;
if(!sb.valid) {
printf("DfsInodeReadBytes: invalid file system\n");
return DFS_FAIL;
}
if(!inodes[handle].valid) {
printf("DfsInodeReadBytes: invalid inode\n");
return DFS_FAIL;
}
while(byte_count < num_bytes) {
blocknum = DfsInodeTranslateVirtualToFilesys(handle, cur_byte / sb.blocksize);
if(blocknum == DFS_FAIL) {
printf("Error: Trying to read from part of file that wasn't written already\n");
return DFS_FAIL;
}
if(DfsReadBlock(blocknum, &dfsb) == DFS_FAIL) {
printf("DfsInodeReadBytes: DfsReadBlock failed\n");
break;
}
data_bytes = sb.blocksize - (cur_byte % sb.blocksize);
if((byte_count + data_bytes) > num_bytes) {
// remove the extra data bytes
data_bytes = data_bytes - ((byte_count + data_bytes) - num_bytes);
}
bcopy(&(dfsb.data[cur_byte % sb.blocksize]), &(mem_bytes[byte_count]), data_bytes);
byte_count += data_bytes;
cur_byte = start_byte + byte_count;
}
return byte_count;
}
int DfsOpenFileSystem() {
int i;
int num;
dfs_block dfs_b;
disk_block disk_b;
//Basic steps:
// Check that filesystem is not already open
// Read superblock from disk. Note this is using the disk read rather
// than the DFS read function because the DFS read requires a valid
// filesystem in memory already, and the filesystem cannot be valid
// until we read the superblock. Also, we don't know the block size
// until we read the superblock, either.
// printf("In DfsOpenFileSystem\n");
// Copy the data from the block we just read into the superblock in memory
// All other blocks are sized by virtual block size:
// Read inodes
// Read free block vector
// Change superblock to be invalid, write back to disk, then change
// it back to be valid in memory
if (sb.valid == 1){
printf("The filesystem is already open!\n");
return DFS_FAIL;
}
if ((num = DiskReadBlock(1,&disk_b)) == DISK_FAIL){
printf("Cannot read superblock from disk!\n");
return DFS_FAIL;
}
bcopy((char *)(&disk_b),(char *)(&sb),sizeof(dfs_superblock));
//print superblock info from disk
/* printf("superblock.valid %d\n",sb.valid);
printf("superblock.filesys_blocksize %d\n",sb.filesys_blocksize);
printf("superblock.filesys_blocknum %d\n",sb.filesys_blocknum);
printf("superblock.filesys_inodestart %d\n",sb.filesys_inodestart);
printf("superblock.inodenum %d\n",sb.inodenum);
printf("superblock.filesys_fbvstart %d\n",sb.filesys_fbvstart);
printf("superblock.filesys_datastart %d\n",sb.filesys_datastart);
*/
for(i=sb.filesys_inodestart;i<sb.filesys_fbvstart;i++){
if (( num = DfsReadBlock (i,&dfs_b)) == DFS_FAIL){
printf("Cannot read inode from disk!\n");
return DFS_FAIL;
}
bcopy((char *)(&dfs_b),(char *)(&inodes[(i-sb.filesys_inodestart)*(sb.filesys_blocksize)/sizeof(dfs_inode)]),sb.filesys_blocksize);
}
SetupRootDir();
//print inode info from disk
// for(i=0;i<192;i++){
// printf("inodes[%d].inuse=%d,inodes[%d].filesize=%d\n",i,inodes[i].inuse,i,inodes[i].filesize);
// }
//
for(i=sb.filesys_fbvstart;i<sb.filesys_datastart;i++){
if (( num = DfsReadBlock(i, &dfs_b)) == DFS_FAIL){
printf("Cannot read free block vector from disk!\n");
return DFS_FAIL;
}
bcopy((char *)(&dfs_b),(char *)(&fbv[(i-sb.filesys_fbvstart)*(sb.filesys_blocksize)/sizeof(uint32)]),sb.filesys_blocksize);
}
//print fbv info from disk
// for(i=0;i<DFS_FBV_MAX_NUM;i++){
// printf("fbv[%d]=0x%x\n",i,fbv[i]);
// }
//
DfsInvalidate();
bzero((char *)(&disk_b),sizeof(disk_block));
bcopy((char *)(&sb),(char *)(&disk_b),sizeof(dfs_superblock));
if (DiskWriteBlock(1,&disk_b) == DISK_FAIL){
printf("Cannot write superblock back to disk!\n");
return DFS_FAIL;
}
sb.valid = 1;
// printf("Exit DfsOpenFileSystem\n");
return DFS_SUCCESS;
}
int DfsInodeWriteBytes(int handle, void *mem, int start_byte, int num_bytes) {
int i;
int end_byte = start_byte+num_bytes-1;
int byte_start,byte_end;
int block_start,block_end;
dfs_block block;
int blocknum;
int byte_write;
// printf("In DfsInodeWriteBytes\n");
if(sb.valid == 0){
printf("File system not opened!\n");
return DFS_FAIL;
}
if((handle<0)||(handle>DFS_INODE_MAX_NUM)){
printf("Invalid inode handle = %d\n",handle);
return DFS_FAIL;
}
if(inodes[handle].inuse == 0){
printf("Inode not allocated!\n");
return DFS_FAIL;
}
if((start_byte<0)||(num_bytes<0)||((end_byte)>(sb.filesys_blocknum*sb.filesys_blocksize))){
printf("Invalid start_byte = %d or num_byte= %d\n",start_byte,num_bytes);
return DFS_FAIL;
}
block_start = (start_byte/sb.filesys_blocksize);
byte_start = (start_byte%sb.filesys_blocksize);
block_end = (end_byte/sb.filesys_blocksize);
byte_end = (end_byte%sb.filesys_blocksize);
if(block_start == block_end){
//check if the virtual block table is valid
if(DfsAllocateCheck(handle,block_start)!= DFS_FAIL){
blocknum = DfsInodeTranslateVirtualToFilesys(handle,block_start);
// printf("write to block(start=end,noalloc) %d\n",blocknum);
DfsReadBlock(blocknum,&block);
bcopy((char *)mem,(char *)((int)&block+byte_start),num_bytes);
DfsWriteBlock(blocknum,&block);
}
else{
if((blocknum = DfsInodeAllocateVirtualBlock(handle,block_start))== DFS_FAIL){
printf("Cannot allocate a virtual block\n");
return DFS_FAIL;
}
// printf("write to block(start=end alloc) %d\n",blocknum);
DfsReadBlock(blocknum,&block);
bzero((char *)&block,sizeof(dfs_block));
bcopy((char *)mem,(char *)((int)&block+byte_start),num_bytes);
DfsWriteBlock(blocknum,&block);
}
inodes[handle].filesize+=num_bytes;
return (num_bytes);
}
else{
if(DfsAllocateCheck(handle,block_start)!=DFS_FAIL){
blocknum = DfsInodeTranslateVirtualToFilesys(handle,block_start);
// printf("write to block(1st,noalloc) %d\n",blocknum);
DfsReadBlock(blocknum,&block);
byte_write = sb.filesys_blocksize-(byte_start);
bcopy((char *)mem,(char *)((int)&block+byte_start),byte_write);
DfsWriteBlock(blocknum,&block);
}
else{
if((blocknum = DfsInodeAllocateVirtualBlock(handle,block_start)) == DFS_FAIL){
printf("Cannot allocate a virtual block!\n");
return DFS_FAIL;
}
// printf("write to block(1st,alloc) %d\n",blocknum);
DfsReadBlock(blocknum,&block);
bzero((char *)&block,sizeof(dfs_block));
byte_write = sb.filesys_blocksize-(byte_start);
bcopy((char *)mem,(char *)((int)&block+byte_start),byte_write);
DfsWriteBlock(blocknum,&block);
}
for(i=(block_start)+1;i<(block_end);i++){
if((DfsAllocateCheck(handle,i)!=DFS_FAIL)){
blocknum = DfsInodeTranslateVirtualToFilesys(handle,i);
// printf("noalloc ");
}
else{
if((blocknum = DfsInodeAllocateVirtualBlock(handle,i)) == DFS_FAIL){
// printf("Cannot allocate a virtual block!\n");
return DFS_FAIL;
}
}
// printf("write to block(middle) %d\n",blocknum);
bzero((char *)&block,sizeof(dfs_block));
bcopy((char *)((int)mem+byte_write),(char *)(&block),sb.filesys_blocksize);
DfsWriteBlock(blocknum,&block);
byte_write +=sb.filesys_blocksize;
}
if(DfsAllocateCheck(handle,block_end)!=DFS_FAIL){
blocknum = DfsInodeTranslateVirtualToFilesys(handle,block_end);
// printf("write to block(last,noalloc) %d\n",blocknum);
DfsReadBlock(blocknum,&block);
bcopy((char *)((int)mem+byte_write),(char *)(&block),(byte_end)+1);
DfsWriteBlock(blocknum,&block);
byte_write +=(byte_end)+1;
}
else{
if((blocknum = DfsInodeAllocateVirtualBlock(handle,block_end)) == DFS_FAIL){
printf("Cannot allocate a virtual block!\n");
return DFS_FAIL;
}
// printf("write to block(last alloc) %d\n",blocknum);
DfsReadBlock(blocknum,&block);
bzero((char *)&block,sizeof(dfs_block));
bcopy((char *)((int)mem+byte_write),(char *)(&block),(byte_end)+1);
DfsWriteBlock(blocknum,&block);
byte_write +=(byte_end)+1;
}
inodes[handle].filesize+=byte_write;
return (byte_write);
}
}
//-----------------------------------------------------------------
// DfsInodeWriteBytes writes num_bytes from the memory pointed to
// by mem to the file represented by the inode handle, starting at
// virtual byte start_byte. Note that if you are only writing part
// of a given file system block, you'll need to read that block
// from the disk first. Return DFS_FAIL on failure and the number
// of bytes written on success.
//-----------------------------------------------------------------
int DfsInodeWriteBytes(uint32 handle, void *mem, int start_byte, int num_bytes) {
int cur_byte = start_byte;
int blocknum;
int data_bytes;
int byte_count = 0;
dfs_block dfsb;
char* mem_bytes = (char*) mem;
if(!sb.valid) {
printf("DfsInodeWriteBytes: invalid file system\n");
return DFS_FAIL;
}
if(!inodes[handle].valid) {
printf("DfsInodeWriteBytes: invalid inode\n");
return DFS_FAIL;
}
while(byte_count < num_bytes) {
// allocate block first checks whether there's existing otherwise allocates
blocknum = DfsInodeAllocateVirtualBlock(handle, cur_byte / sb.blocksize);
data_bytes = sb.blocksize - (cur_byte % sb.blocksize);
if(data_bytes == sb.blocksize) {
// the start is blocksize aligned
// check if end is not block aligned
if((byte_count + data_bytes) > num_bytes) {
// remove the extra data bytes
data_bytes = data_bytes - ((byte_count + data_bytes) - num_bytes);
// not block aligned so read whole block
if(DfsReadBlock(blocknum, &dfsb) == DFS_FAIL) {
printf("DfsInodeReadBytes: DfsReadBlock failed\n");
break;
}
}
}
else {
// start is not block algined
// check if end is not block aligned
if((byte_count + data_bytes) > num_bytes) {
// remove the extra data bytes
data_bytes = data_bytes - ((byte_count + data_bytes) - num_bytes);
}
// We need to do this any way since start is not block aligned
if(DfsReadBlock(blocknum, &dfsb) == DFS_FAIL) {
printf("DfsInodeWriteBytes: DfsReadBlock failed\n");
break;
}
}
bcopy(&(mem_bytes[byte_count]), &(dfsb.data[cur_byte % sb.blocksize]), data_bytes);
if(DfsWriteBlock(blocknum, &dfsb) == DFS_FAIL) {
printf("DfsInodeWriteBytes: DfsWriteBlock failed\n");
break;
}
byte_count += data_bytes;
cur_byte = start_byte + byte_count;
}
if(inodes[handle].filesize < (start_byte + byte_count)) {
inodes[handle].filesize = start_byte + byte_count;
}
return byte_count;
}
uint32 DfsInodeAllocateVirtualBlock(uint32 handle, uint32 virtual_blocknum) {
dfs_block dfsb;
int blocknum;
int* block_entry_table;
if(!sb.valid) {
printf("DfsInodeAllocateVirtualBlock: invalid file system\n");
return DFS_FAIL;
}
if(!inodes[handle].valid) {
printf("DfsInodeAllocateVirtualBlock: invalid inode\n");
return DFS_FAIL;
}
if(virtual_blocknum >= 10) {
block_entry_table = (int*) dfsb.data;
if(!DFS_IS_BLOCK_ENTRY_VALID(inodes[handle].indir_block_entry)) {
blocknum = DfsAllocateBlock();
if(blocknum == DFS_FAIL) {
printf("DfsInodeAllocateVirtualBlock: DfsAllocateBlock failed\n");
return DFS_FAIL;
}
bzero(dfsb.data, sb.blocksize);
DfsWriteBlock(blocknum, &dfsb);
inodes[handle].indir_block_entry = DFS_SET_BLOCK_ENTRY(blocknum, 1);
}
DfsReadBlock(DFS_GET_BLOCK_NUM(inodes[handle].indir_block_entry), &dfsb);
virtual_blocknum -= 10;
// Before allocating new block
// Extra check to make sure that there is no already valid entry here
if(DFS_IS_BLOCK_ENTRY_VALID(block_entry_table[virtual_blocknum])) {
return DFS_GET_BLOCK_NUM(block_entry_table[virtual_blocknum]);
}
else {
blocknum = DfsAllocateBlock();
if(blocknum == DFS_FAIL) {
printf("DfsInodeAllocateVirtualBlock: DfsAllocateBlock failed\n");
return DFS_FAIL;
}
block_entry_table[virtual_blocknum] = DFS_SET_BLOCK_ENTRY(blocknum, 1);
DfsWriteBlock(DFS_GET_BLOCK_NUM(inodes[handle].indir_block_entry), &dfsb);
}
return blocknum;
}
else {
block_entry_table = inodes[handle].direct_block_entries;
// Before allocating new block
// Extra check to make sure that there is no already valid entry here
if(DFS_IS_BLOCK_ENTRY_VALID(block_entry_table[virtual_blocknum])) {
return DFS_GET_BLOCK_NUM(block_entry_table[virtual_blocknum]);
}
else {
blocknum = DfsAllocateBlock();
if(blocknum == DFS_FAIL) {
printf("DfsInodeAllocateVirtualBlock: DfsAllocateBlock failed\n");
return DFS_FAIL;
}
block_entry_table[virtual_blocknum] = DFS_SET_BLOCK_ENTRY(blocknum, 1);
return blocknum;
}
}
printf("---THIS SHOULD NOT HAPPEN---\n");
return DFS_FAIL;
}