58 lines
1.7 KiB
C
58 lines
1.7 KiB
C
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// On-disk file system format.
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// Both the kernel and user programs use this header file.
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#define ROOTINO 1 // root i-number
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#define BSIZE 512 // block size
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// Disk layout:
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// [ boot block | super block | log | inode blocks |
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// free bit map | data blocks]
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//
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// mkfs computes the super block and builds an initial file system. The
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// super block describes the disk layout:
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struct superblock {
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uint size; // Size of file system image (blocks)
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uint nblocks; // Number of data blocks
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uint ninodes; // Number of inodes.
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uint nlog; // Number of log blocks
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uint logstart; // Block number of first log block
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uint inodestart; // Block number of first inode block
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uint bmapstart; // Block number of first free map block
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};
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#define NDIRECT 12
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#define NINDIRECT (BSIZE / sizeof(uint))
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#define MAXFILE (NDIRECT + NINDIRECT)
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// On-disk inode structure
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struct dinode {
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short type; // File type
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short major; // Major device number (T_DEV only)
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short minor; // Minor device number (T_DEV only)
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short nlink; // Number of links to inode in file system
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uint size; // Size of file (bytes)
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uint addrs[NDIRECT + 1]; // Data block addresses
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};
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// Inodes per block.
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#define IPB (BSIZE / sizeof(struct dinode))
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// Block containing inode i
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#define IBLOCK(i, sb) ((i) / IPB + sb.inodestart)
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// Bitmap bits per block
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#define BPB (BSIZE * 8)
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// Block of free map containing bit for block b
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#define BBLOCK(b, sb) (b / BPB + sb.bmapstart)
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// Directory is a file containing a sequence of dirent structures.
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#define DIRSIZ 14
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struct dirent {
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ushort inum;
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char name[DIRSIZ];
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};
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