/*
* Resize a file.
* This file should be opened (in the file descriptor table). The new size
* should be larger than the old one (not supposed to shrink a file)
*/
static void sfs_resize_file(int fd, u32 new_size)
{
/* the length of content that can be hold by a full frame (in bytes) */
int frame_size = BLOCK_SIZE * SFS_FRAME_COUNT;
/* old file size */
int old_size = fdtable[fd].inode.size;
/* how many frames are used before resizing */
int old_nframe = (old_size + frame_size -1) / frame_size;
/* how many frames are required after resizing */
int new_nframe = (new_size + frame_size - 1) / frame_size;
int i, j;
blkid frame_bid = 0;
sfs_inode_frame_t frame;
blkid bid, content_bid;
/* TODO: check if new frames are required */
if (new_nframe - old_nframe > 0)
{
/* TODO: allocate a full frame */
frame_bid = sfs_alloc_block();
for (j = 0; j < SFS_FRAME_COUNT; j++)
{
content_bid = sfs_alloc_block();
frame.content[j] = content_bid;
// Empty content block
char tmp[BLOCK_SIZE];
memset(tmp, 0, BLOCK_SIZE);
sfs_write_block((char*)&tmp, content_bid);
}
/* TODO: add the new frame to the inode frame list
Note that if the inode is changed, you need to write it to the disk
*/
bid = fdtable[fd].inode.first_frame;
if (bid == 0)
{
fdtable[fd].inode.first_frame = frame_bid;
sfs_write_block((char*)&fdtable[fd].inode, fdtable[fd].inode_bid);
}
else
{
for (i = 0; i < SFS_FRAME_COUNT; i++)
{
if (bid == 0)
{
frame.next = frame_bid;
break;
}
sfs_read_block((char*)&frame, bid);
bid = frame.next;
}
}
// Write the new frame block
sfs_write_block((char*)&frame, frame_bid);
}
}
/*
* Get the bids of content blocks that hold the file content starting from cur
* to cur+length. These bids are stored in the given array.
* The caller of this function is supposed to allocate the memory for this
* array. It is guaranteed that cur+length<size
*
* This function returns the number of bids being stored to the array.
*/
static u32 sfs_get_file_content(blkid *bids, int fd, u32 cur, u32 length)
{
u32 start; //Starting block of content
u32 end; //Ending block of content
sfs_inode_t inode;
sfs_inode_frame_t frame;
blkid frame_bid;
char tmp[BLOCK_SIZE];
char frame_ptr[BLOCK_SIZE];
u32 num_bids = 0; //Counts the number of bids in the array
//Get the bid of the desired frame
fd_struct_t fd_struct = fdtable[fd];
sfs_read_block(tmp, fd_struct.inode_bid);
inode = *(sfs_inode_t*)tmp;
frame_bid = inode.first_frame;
start = cur / BLOCK_SIZE;
end = (cur + length) / BLOCK_SIZE;
u32 numBlocks = end - start + 1;
u32 blocks_remaining = numBlocks;
u32 original_blocks = blocks_remaining;
//Start searching at an offset determined by the start position
u32 block_count = start % SFS_FRAME_COUNT;
//This loop will iterate through the frames
while(blocks_remaining > 0){
sfs_read_block(frame_ptr, frame_bid);
frame = *(sfs_inode_frame_t*)frame_ptr;
//Iterate through the content array of the frame
while(block_count < SFS_FRAME_COUNT && blocks_remaining > 0){
//Allocate a content block if it is not yet set
if(frame.content[block_count] == 0){
frame.content[block_count] = sfs_alloc_block();
}
bids[num_bids] = frame.content[block_count];
num_bids++;
block_count++;
blocks_remaining--;
}
sfs_write_block(&frame, frame_bid);
if(blocks_remaining != 0){
frame_bid = frame.next;
block_count = 0;
}
}
return num_bids;
}
/*
* Create a new directory and return 0 on success.
* If the dir already exists, return -1.
*/
int sfs_mkdir(char *dirname)
{
/* TODO: test if the dir exists */
/* TODO: insert a new dir to the linked list */
blkid nextBlkid;
sfs_dirblock_t dir, new_dir;
// Try finding the directory if it exists
blkid bid = sfs_find_dir(dirname);
if (bid == 0)
{
// Directory does not exists, create a new one
bid = sfs_alloc_block();
// Add the new directory to the directory linked list
nextBlkid = sb.first_dir;
if (nextBlkid == 0) {
sb.first_dir = bid;
sfs_write_block((char*)&sb, 0);
}
else
{
sfs_read_block((char*)&dir, nextBlkid);
while (dir.next_dir != 0)
{
nextBlkid = dir.next_dir;
sfs_read_block((char*)&dir, nextBlkid);
}
dir.next_dir = bid;
sfs_write_block((char*)&dir, nextBlkid);
}
// Create new directory with next_dir=0 and dir_name
new_dir.next_dir = 0;
memset(new_dir.dir_name, 0, sizeof(new_dir.dir_name)); // Empty dir_name
memset(new_dir.inodes, 0, sizeof(new_dir.inodes)); // Empty inodes
strcpy(new_dir.dir_name, dirname); // Copy new dir_name
sfs_write_block((char*)&new_dir, bid);
return 0;
}
// Directory already exists
return -1;
}
W
sfs_i_write (struct inode *ip,
W start,
B *buf,
W size,
W *rsize)
{
#ifdef notdef
B blockbuf[ip->i_fs->fs_private.sfs_fs.sfs_blocksize]; /* GCC の拡張機能を使っている */
#endif
int copysize;
int offset;
int retsize;
int filesize;
ID fd;
struct fs *fsp;
W bn;
W cn;
B *cbuf;
#ifdef FMDEBUG
printk ("sfs_i_write:(start = %d, size = %d)\n", start, size); /* */
#endif
*rsize = 0;
retsize = size;
filesize = start + retsize;
fd = ip->i_device;
fsp = ip->i_fs;
#ifdef FMDEBUG
printk ("sfs_i_write: size = %d\n", size); /* */
#endif
while (size > 0)
{
#ifdef FMDEBUG
printk ("%s\n",
(sfs_get_block_num (fd, fsp, &(ip->i_private.sfs_inode),
start / fsp->fs_blksize) <= 0) ?
"allocate block" : "read block");
#endif
if (sfs_get_block_num (fd, fsp, &(ip->i_private.sfs_inode),
start / fsp->fs_blksize) <= 0)
{
/* ファイルサイズを越えて書き込む場合には、新しくブロックをアロケートする
*/
bn = sfs_set_block_num (fd, fsp, &(ip->i_private.sfs_inode),
start / fsp->fs_blksize,
sfs_alloc_block (fd, fsp));
/*
* ip->sfs_i_direct[start / fsp->fs_blksize] = alloc_block (fd, fsp);
*/
#ifdef notdef
bzero (blockbuf, fsp->fs_blksize);
#else
if (bn < 0) {
return (EP_IO);
}
sfs_get_cache(fd, bn, &cn, &cbuf);
#endif
}
else
{
#ifdef FMDEBUG
printk ("read block %d\n",
sfs_get_block_num (fd, fsp, &(ip->i_private.sfs_inode),
start / fsp->fs_blksize));
#endif
bn = sfs_get_block_num (fd, fsp, &(ip->i_private.sfs_inode),
start / fsp->fs_blksize);
if (bn < 0) {
return (EP_IO);
}
#ifdef notdef
sfs_read_block (fd, bn, fsp->fs_blksize, blockbuf);
#else
sfs_get_cache(fd, bn, &cn, &cbuf);
#endif
}
/* 読み込んだブロックの内容を更新する
*/
offset = start % fsp->fs_blksize;
copysize = MIN (fsp->fs_blksize - offset, size);
#ifdef FMDEBUG
printk ("*** read block contents ***\n");
{
int i;
char tmpbuf[2];
tmpbuf[1] = '\0';
printk ("copy size: %d\n", copysize);
for (i = 0; i < copysize; i++)
{
tmpbuf[0] = blockbuf[i];
printk ("%s", tmpbuf);
}
}
#endif
#ifdef notdef
bcopy (buf, &blockbuf[offset], copysize);
#else
bcopy(buf, &cbuf[offset], copysize);
#endif
#ifdef notdef
printk ("sfs write block: block number = %d\n",
sfs_get_block_num (fd, fsp, &(ip->i_private.sfs_inode),
start / fsp->fs_blksize)); /* */
#endif
/* 更新したブロックを書き込む
*/
#ifdef notdef
bn = sfs_get_block_num (fd, fsp, &(ip->i_private.sfs_inode),
start / fsp->fs_blksize);
if (bn < 0) {
return (EP_IO);
}
sfs_write_block (fd, bn, fsp->fs_blksize, blockbuf);
#else
sfs_put_cache(cn, 1);
#endif
buf += copysize;
start += copysize;
size -= copysize;
}
/* cache の sync をここで行う必要はあるか? */
sfs_sync_cache(fd);
/* もし、書き込みをおこなった後にファイルのサイズが増えていれば、
* サイズを更新して inode を書き込む。
*/
if (filesize > ip->i_private.sfs_inode.sfs_i_size)
{
ip->i_size = filesize;
ip->i_size_blk =
ROUNDUP(filesize, fsp->fs_blksize)/fsp->fs_blksize;
ip->i_dirty = 1;
/* これは deallocate の中で処理するのが普通 */
sfs_i_sync(ip);
}
else if (filesize < ip->i_private.sfs_inode.sfs_i_size) {
sfs_i_truncate (ip, filesize);
}
*rsize = retsize - size;
#ifdef FMDEBUG
printk ("write size: %d bytes\n", *rsize);
#endif
return (EP_OK);
}
/*
* Open a file. If it does not exist, create a new one.
* Allocate a file desriptor for the opened file and return the fd.
*/
int sfs_open(char *dirname, char *name)
{
blkid dir_bid = 0, inode_bid = 0;
char inode_ptr[BLOCK_SIZE];
sfs_inode_t inode;
sfs_dirblock_t dir;
fd_struct_t *fd_ptr;
fd_struct_t fd;
//Finds a free file descriptor number
int fd_num = 0;
while(fd_num < SFS_MAX_OPENED_FILES){
fd = fdtable[fd_num];
if(fd.valid == 0){
fd.valid = 1;
fd.cur = 0;
break;
} else if(fd_num == SFS_MAX_OPENED_FILES - 1){
printf("The maximum number of files are already in use\n");
return -1;
} else{
fd_num++;
}
}
//Find the directory in which the specified file is contained
dir_bid = sfs_find_dir(dirname);
sfs_read_block(&dir, dir_bid);
fd.dir_bid = dir_bid;
//Iterate through all the indices of the inodes to find the file
int count = 0;
int fd_set = 0;
int free_inode = -1;
char *file_name;
while(count < SFS_DB_NINODES){
inode_bid = dir.inodes[count];
if(inode_bid == 0){
if(free_inode == -1){
free_inode = count;
}
count++;
continue;
}
//Read the inode at the specified index
sfs_read_block(inode_ptr, inode_bid);
inode = *(sfs_inode_t*)inode_ptr;
file_name = inode.file_name;
if(strcmp(file_name, name) == 0){
fd.inode = inode;
fd.inode_bid = inode_bid;
fd_set = 1;
break;
}
count++;
}
//Create a new file
if(fd_set == 0){
//Allocate a block for the inode
blkid new_inode_bid = sfs_alloc_block();
//Put the inode bid into the directory inode array
dir.inodes[free_inode] = new_inode_bid;
sfs_write_block(&dir, dir_bid);
strcpy(inode.file_name, name);
//Allocate a block for the first frame
blkid new_frame_bid = sfs_alloc_block();
inode.first_frame = new_frame_bid;
inode.size = 0;
//Place the inode in the file descriptor array
fd.inode = inode;
fd.inode_bid = new_inode_bid;
sfs_write_block(&inode, new_inode_bid);
sfs_read_block(&inode, new_inode_bid);
//Allocate a block for the first content block of the frame
char tmp[BLOCK_SIZE];
sfs_read_block(tmp, new_frame_bid);
sfs_inode_frame_t new_frame = *(sfs_inode_frame_t*)tmp;
blkid new_content_bid = sfs_alloc_block();
new_frame.content[0] = new_content_bid;
sfs_write_block(&new_frame, new_frame_bid);
}
//Set the file descriptor in the file descriptor table
fdtable[fd_num] = fd;
return fd_num;
}
/*
* Create a new directory and return 0 on success.
* If the dir already exists, return -1.
*/
int sfs_mkdir(char *dirname)
{
//Check if the directory has a valid name
if(sizeof(dirname) > 120){
printf("Dir name exceeds max allowed characters.\n");
return -1;
}
//Test if the dir exists
if(sfs_find_dir(dirname) != 0){
return -1;
} else{
//Initialize variables
blkid next_dir_id;
char block_ptr[BLOCK_SIZE];
sfs_dirblock_t dir;
//Allocate space for a new block
blkid new_bid = sfs_alloc_block();
//Set the next_dir in the last directory block
next_dir_id = sb.first_dir;
sfs_read_block(block_ptr, next_dir_id);
dir = *(sfs_dirblock_t*)block_ptr;
if(next_dir_id == 0){
sb.first_dir = new_bid;
sfs_write_block(&sb, 0);
} else{
while(next_dir_id != 0){
sfs_read_block(block_ptr, next_dir_id);
dir = *(sfs_dirblock_t*)block_ptr;
//Next dir is zero, set it to the next available block
if(dir.next_dir == 0){
blkid modified_dir_id = next_dir_id;
sfs_read_block(block_ptr, modified_dir_id);
dir = *(sfs_dirblock_t*)block_ptr;
dir.next_dir = new_bid;
//A value was changed, so this must be flushed to disk
sfs_write_block(&dir, modified_dir_id);
next_dir_id = 0;
} else{
next_dir_id = dir.next_dir;
}
}
}
//Create a temporary directory and initialize its members
//Set the next dir, name, and set all its inodes to zero
sfs_dirblock_t temp_dir;
temp_dir.next_dir = 0;
strcpy(temp_dir.dir_name, dirname);
memset(&temp_dir.inodes[0], 0, SFS_DB_NINODES * sizeof(blkid));
//Write the temporary block into the disk
sfs_write_block(&temp_dir, new_bid);
}
return 0;
}
/*
* Resize a file.
* This file should be opened (in the file descriptor table). The new size
* should be larger than the old one (not supposed to shrink a file)
*/
static void sfs_resize_file(int fd, u32 new_size)
{
/* the length of content that can be hold by a full frame (in bytes) */
int frame_size = BLOCK_SIZE * SFS_FRAME_COUNT;
/* old file size */
int old_size = fdtable[fd].inode.size;
/* how many frames are used before resizing */
int old_nframe = (old_size + frame_size -1) / frame_size;
//Opening a file always results in at least one frame
if(old_nframe == 0){
old_nframe++;
}
/* how many frames are required after resizing */
int new_nframe = (new_size + frame_size - 1) / frame_size;
int i, j;
char inode_ptr[BLOCK_SIZE];
char tmp[BLOCK_SIZE];
sfs_inode_t inode;
sfs_read_block(inode_ptr, fdtable[fd].inode_bid);
inode = *(sfs_inode_t*)inode_ptr;
blkid frame_bid = inode.first_frame;
sfs_inode_frame_t frame;
/* TODO: check if new frames are required */
int count = old_nframe;
while(count < new_nframe){
sfs_read_block(tmp, frame_bid);
frame = *(sfs_inode_frame_t*)tmp;
blkid new_frame_bid = sfs_alloc_block();
//Update the next frame bid for the current frame
frame.next = new_frame_bid;
sfs_write_block(&frame, frame_bid);
//Read the new frame bid and add the content blocks
sfs_read_block(tmp, new_frame_bid);
frame = *(sfs_inode_frame_t*)tmp;
for(i = 0; i < SFS_FRAME_COUNT; i++){
frame.content[i] = sfs_alloc_block();
}
sfs_write_block(&frame, new_frame_bid);
frame_bid = new_frame_bid;
count++;
}
sfs_read_block(tmp, inode.first_frame);
frame = *(sfs_inode_frame_t*)tmp;
inode.size = new_size;
sfs_write_block(&inode, fdtable[fd].inode_bid);
sfs_read_block(tmp, fdtable[fd].inode_bid);
inode = *(sfs_inode_t*)tmp;
}
/*
* Open a file. If it does not exist, create a new one.
* Allocate a file desriptor for the opened file and return the fd.
*/
int sfs_open(char *dirname, char *name)
{
blkid dir_bid = 0, inode_bid = 0;
sfs_inode_t *inode, new_inode;
sfs_dirblock_t dir;
int fd;
int i;
/* TODO: find a free fd number */
for (i = 0; i < SFS_MAX_OPENED_FILES; i++)
{
if (fdtable[i].valid == 0)
{
// Found a free fd
fd = i;
break;
}
}
/* TODO: find the dir first */
dir_bid = sfs_find_dir(dirname);
if (dir_bid == 0)
{
printf("ERROR: the directory does not exists\n");
return -1;
}
sfs_read_block((char*)&dir, dir_bid);
/* TODO: traverse the inodes to see if the file exists.
If it exists, load its inode. Otherwise, create a new file.
*/
for (i = 0; i < SFS_DB_NINODES; i++)
{
if (dir.inodes[i] != 0)
{
sfs_read_block((char*)&new_inode, dir.inodes[i]);
if (strcmp(new_inode.file_name, name) == 0) {
inode_bid = dir.inodes[i];
break;
}
}
}
if (inode_bid == 0)
{
// Allocate a block to store new inode
inode_bid = sfs_alloc_block();
// Find empty space in dir.inodes[] and set inode_bid
for (i=0; i<SFS_DB_NINODES; i++)
{
if (dir.inodes[i] == 0)
{
dir.inodes[i] = inode_bid;
break;
}
}
// Did not find the inode, create a new one
new_inode.first_frame = 0;
new_inode.size = 0;
memset(new_inode.file_name, 0, sizeof(new_inode.file_name));
strcpy(new_inode.file_name, name);
sfs_write_block((char*)&new_inode, inode_bid);
sfs_write_block((char*)&dir, dir_bid);
}
/* TODO: create a new file */
fdtable[fd].dir_bid = dir_bid;
fdtable[fd].inode_bid = inode_bid;
fdtable[fd].inode = new_inode;
fdtable[fd].cur = 0;
fdtable[fd].valid = 1;
return fd;
}
