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// On-disk file system format.
// Both the kernel and user programs use this header file.
// Block 0 is unused.
// Block 1 is super block.
// Inodes start at block 2.
#define BSIZE 512 // block size
// File system super block
struct superblock {
uint size; // Size of file system image (blocks)
uint nblocks; // Number of data blocks
uint ninodes; // Number of inodes.
};
#define NADDRS (NDIRECT+1)
#define NDIRECT 12
#define INDIRECT 12
#define NINDIRECT (BSIZE / sizeof(uint))
#define MAXFILE (NDIRECT + NINDIRECT)
// On-disk inode structure
struct dinode {
short type; // File type
short major; // Major device number (T_DEV only)
short minor; // Minor device number (T_DEV only)
short nlink; // Number of links to inode in file system
uint size; // Size of file (bytes)
uint addrs[NADDRS]; // Data block addresses
};
#define T_DIR 1 // Directory
#define T_FILE 2 // File
#define T_DEV 3 // Special device
// Inodes per block.
#define IPB (BSIZE / sizeof(struct dinode))
// Block containing inode i
#define IBLOCK(i) ((i) / IPB + 2)
// Bitmap bits per block
#define BPB (BSIZE*8)
// Block containing bit for block b
#define BBLOCK(b, ninodes) (b/BPB + (ninodes)/IPB + 3)
// PAGEBREAK: 10
// Directory is a file containing a sequence of dirent structures.
#define DIRSIZ 14
struct dirent {
ushort inum;
char name[DIRSIZ];
};
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