File system access library.
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281
src/libdiskfs/ffs.h
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281
src/libdiskfs/ffs.h
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/*
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* An FFS file system is a sequence of cylinder groups.
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*
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* Each cylinder group is laid out as follows:
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*
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* fs superblock (Fsblk)
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* cylinder group block (Cgblk)
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* inodes
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* data
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*
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* The location of the fs superblock in the first cylinder
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* group is known. The rest of the info about cylinder group
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* layout can be derived from the super block.
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*/
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#define daddr_t u32int
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#define time_t u32int
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typedef struct Cgblk Cgblk;
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typedef struct Cylgrp Cylgrp;
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typedef struct Cylsum Cylsum;
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typedef struct Ffs Ffs;
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typedef struct Fsblk Fsblk;
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typedef struct Inode Inode;
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typedef struct Dirent Dirent;
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enum
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{
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BYTESPERSEC = 512,
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/* constants for Fsblk */
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FSMAXMNTLEN = 512,
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FSNOCSPTRS = 128 / sizeof(void*) - 3,
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FSMAXSNAP = 20,
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FSMAGIC = 0x011954,
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FSCHECKSUM = 0x7c269d38,
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/* Fsblk.inodefmt */
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FS42INODEFMT = -1,
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FS44INODEFMT = 2,
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/* offset and size of first boot block */
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BBOFF = 0,
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BBSIZE = 8192,
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/* offset and size of first super block */
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SBOFF = BBOFF+BBSIZE,
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SBSIZE = 8192,
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/* minimum block size */
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MINBSIZE = 4096,
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/* maximum fragments per block */
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MAXFRAG = 8,
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/* constants for Cgblk */
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CGMAGIC = 0x090255,
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/* inode-related */
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ROOTINODE = 2,
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WHITEOUT = 1,
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NDADDR = 12,
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NIADDR = 3,
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/* permissions in Inode.mode */
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IEXEC = 00100,
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IWRITE = 0200,
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IREAD = 0400,
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ISVTX = 01000,
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ISGID = 02000,
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ISUID = 04000,
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/* type in Inode.mode */
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IFMT = 0170000,
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IFIFO = 0010000,
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IFCHR = 0020000,
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IFDIR = 0040000,
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IFBLK = 0060000,
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IFREG = 0100000,
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IFLNK = 0120000,
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IFSOCK = 0140000,
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IFWHT = 0160000,
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/* type in Dirent.type */
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DTUNKNOWN = 0,
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DTFIFO = 1,
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DTCHR = 2,
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DTDIR = 4,
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DTBLK = 6,
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DTREG = 8,
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DTLNK = 10,
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DTSOCK = 12,
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DTWHT = 14,
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};
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struct Cylsum
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{
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u32int ndir;
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u32int nbfree;
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u32int nifree;
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u32int nffree;
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};
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struct Fsblk
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{
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u32int unused0;
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u32int unused1;
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daddr_t sfragno; /* fragment address of super block in file system */
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daddr_t cfragno; /* fragment address if cylinder block in file system */
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daddr_t ifragno; /* fragment offset of inode blocks in file system */
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daddr_t dfragno; /* fragment offset of data blocks in cg */
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u32int cgoffset; /* block (maybe fragment?) offset of Cgblk in cylinder */
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u32int cgmask;
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time_t time;
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u32int nfrag; /* number of blocks in fs * fragsperblock */
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u32int ndfrag;
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u32int ncg; /* number of cylinder groups in fs */
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u32int blocksize; /* block size in fs */
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u32int fragsize; /* frag size in fs */
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u32int fragsperblock; /* fragments per block: blocksize / fragsize */
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u32int minfree; /* ignored by us */
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u32int rotdelay; /* ... */
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u32int rps;
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u32int bmask;
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u32int fmask;
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u32int bshift;
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u32int fshift;
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u32int maxcontig;
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u32int maxbpg;
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u32int fragshift;
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u32int fsbtodbshift;
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u32int sbsize; /* size of super block */
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u32int unused2; /* more stuff we don't use ... */
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u32int unused3;
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u32int nindir;
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u32int inosperblock; /* inodes per block */
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u32int nspf;
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u32int optim;
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u32int npsect;
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u32int interleave;
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u32int trackskew;
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u32int id[2];
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daddr_t csaddr; /* blk addr of cyl grp summary area */
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u32int cssize; /* size of cyl grp summary area */
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u32int cgsize; /* cylinder group size */
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u32int trackspercyl; /* tracks per cylinder */
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u32int secspertrack; /* sectors per track */
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u32int secspercyl; /* sectors per cylinder */
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u32int ncyl; /* cylinders in fs */
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u32int cylspergroup; /* cylinders per group */
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u32int inospergroup; /* inodes per group */
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u32int fragspergroup; /* data blocks per group * fragperblock */
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Cylsum cstotal; /* more unused... */
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u8int fmod;
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u8int clean;
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u8int ronly;
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u8int flags;
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char fsmnt[FSMAXMNTLEN];
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u32int cgrotor;
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void* ocsp[FSNOCSPTRS];
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u8int* contigdirs;
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Cylsum* csp;
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u32int* maxcluster;
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u32int cpc;
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u16int opostbl[16][8];
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u32int snapinum[FSMAXSNAP];
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u32int avgfilesize;
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u32int avgfpdir;
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u32int sparecon[26];
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u32int pendingblocks;
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u32int pendinginodes;
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u32int contigsumsize;
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u32int maxsymlinklen;
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u32int inodefmt; /* format of on-disk inodes */
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u64int maxfilesize; /* maximum representable file size */
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u64int qbmask;
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u64int qfmask;
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u32int state;
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u32int postblformat;
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u32int nrpos;
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u32int postbloff;
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u32int rotbloff;
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u32int magic; /* FS_MAGIC */
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};
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/*
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* Cylinder group block for a file system.
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*/
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struct Cgblk
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{
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u32int unused0;
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u32int magic; /* CGMAGIC */
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u32int time; /* time last written */
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u32int num; /* we are cg #cgnum */
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u16int ncyl; /* number of cylinders in gp */
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u16int nino; /* number of inodes */
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u32int nfrag; /* number of fragments */
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Cylsum csum;
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u32int rotor;
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u32int frotor;
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u32int irotor;
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u32int frsum[MAXFRAG]; /* counts of available frags */
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u32int btotoff;
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u32int boff;
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u32int imapoff; /* offset to used inode map */
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u32int fmapoff; /* offset to free fragment map */
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u32int nextfrag; /* next free fragment */
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u32int csumoff;
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u32int clusteroff;
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u32int ncluster;
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u32int sparecon[13];
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};
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struct Cylgrp
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{
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/* these are block numbers not fragment numbers */
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u32int bno; /* disk block address of start of cg */
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u32int ibno; /* disk block address of first inode */
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u32int dbno; /* disk block address of first data */
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u32int cgblkno;
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};
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/*
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* this is the on-disk structure
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*/
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struct Inode
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{
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u16int mode;
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u16int nlink;
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u32int unused;
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u64int size;
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u32int atime;
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u32int atimensec;
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u32int mtime;
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u32int mtimensec;
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u32int ctime;
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u32int ctimensec;
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/* rdev is db[0] */
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u32int db[NDADDR];
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u32int ib[NIADDR];
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u32int flags;
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u32int nblock;
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u32int gen;
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u32int uid;
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u32int gid;
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u32int spare[2];
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};
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struct Dirent
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{
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u32int ino;
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u16int reclen;
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u8int type;
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u8int namlen;
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char name[1];
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};
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/*
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* main file system structure
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*/
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struct Ffs
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{
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int blocksize;
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int nblock;
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int fragsize;
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int fragsperblock;
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int inosperblock;
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int blockspergroup;
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int fragspergroup;
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int inospergroup;
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u32int nfrag;
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u32int ndfrag;
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int ncg;
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Cylgrp *cg;
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Disk *disk;
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};
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