struct unixfilesystem *
unixfilesystem_format(int dfd)
{
uint16_t bootblock[256];
bootblock[0] = BOOTBLOCK_MAGIC_NUM;
diskimg_writesector(dfd, BOOTBLOCK_SECTOR, bootblock);
struct unixfilesystem *fs = malloc(sizeof(struct unixfilesystem));
if (fs == NULL) {
fprintf(stderr,"Out of memory.\n");
return NULL;
}
fs->dfd = dfd;
// 144 inodes in total, so we have 8 blocks
// to store inodes, plus 2 start blocks,
// we have 10 blocks in use, and we allocate the entire volume 110 blocks
// so the rest 100 blocks is file blocks, and all blocks formats to free.
fs->superblock.s_isize = 144;
fs->superblock.s_fsize = 110; // 110 blocks of entire volume
fs->superblock.s_ninode = fs->superblock.s_isize; // at begining, free inodes number = total inodes number
int i;
// consider s_inode as bitmap
for (i = 0;i < 100;i++)
fs->superblock.s_inode[i] = 0;
fs->superblock.s_nfree = fs->superblock.s_fsize ; // at begining, free blocks number = total blocks number
// consider s_free as bitmap
for (i = 0;i < 100;i++)
fs->superblock.s_free[i] = 0;
diskimg_writesector(dfd, SUPERBLOCK_SECTOR, &fs->superblock);
int inumber = filsys_allocInode(fs);
if (inumber != ROOT_INUMBER) {
fprintf(stderr, "ROOT_INUMBER is not 1, format failed\n");
return -1;
}
struct inode in;
inode_iget(fs, inumber, &in);
// format the root dir, and set the i_mode field to DIR
inode_format(&in);
//in.i_mode &= (0xffff - IFMT);
in.i_mode |= IFDIR;
inode_iwrite(fs, ROOT_INUMBER, &in);
fs->workDirInumber = ROOT_INUMBER;
strcpy(fs->workDirName, "/");
return fs;
}
int remove_file(struct unixfilesystem *fs, int inumber)
{
struct inode in;
int err = inode_iget(fs, inumber, &in);
if (err < 0) return -1;
if (!(in.i_mode & IALLOC) || ((in.i_mode & IFMT) == IFDIR))
{
/* Not allocated or is a directory */
fprintf(stderr, "The input path is not a file and cannot be removed");
return -1;
}
if (in.i_nlink == 1) // only one link, so overwrite the file
{
char zeros[DISKIMG_SECTOR_SIZE] = {0};
int size = inode_getsize(&in);
int blockNum = 0;
// overwrite the file with zeros
for (blockNum = 0; blockNum < size / DISKIMG_SECTOR_SIZE; blockNum++)
{
char buf[DISKIMG_SECTOR_SIZE];
int blockAddress = inode_indexlookup(fs, &in, blockNum);
if (blockAddress == -1) {
fprintf(stderr, "Error looking up block number %d in inode %d", blockNum, inumber);
return -1;
}
if (diskimg_writesector(fs->dfd, blockAddress, &zeros) == -1)
{
fprintf(stderr, "Error overwriting file");
return -1;
}
}
}
else // multiple links to file, so only remove this link
{
in.i_nlink--;
}
return 0;
}
