minix/boot/rawfs.c

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/* rawfs.c - Raw Minix file system support. Author: Kees J. Bot
* 23 Dec 1991
* Based on readfs by Paul Polderman
*/
#define nil 0
#define _POSIX_SOURCE 1
#define _MINIX 1
#include <sys/types.h>
#include <sys/stat.h>
#include <stdlib.h>
#include <limits.h>
#include <string.h>
#include <errno.h>
#include <minix/config.h>
#include <minix/const.h>
#include <minix/type.h>
#include <servers/mfs/const.h>
#include <servers/mfs/type.h>
#include <servers/mfs/buf.h>
#include <servers/mfs/super.h>
#include <servers/mfs/inode.h>
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#include "rawfs.h"
void readblock(off_t blockno, char *buf, int);
/* The following code handles two file system types: Version 1 with small
* inodes and 16-bit disk addresses and Version 2 with big inodes and 32-bit
* disk addresses.
#ifdef FLEX
* To make matters worse, Minix-vmd knows about the normal Unix Version 7
* directories and directories with flexible entries.
#endif
*/
/* File system parameters. */
static unsigned nr_dzones; /* Fill these in after reading superblock. */
static unsigned nr_indirects;
static unsigned inodes_per_block;
static int block_size;
#ifdef FLEX
#include <dirent.h>
#define direct _v7_direct
#else
#include <sys/dir.h>
#endif
#if __minix_vmd
static struct v12_super_block super; /* Superblock of file system */
#define s_log_zone_size s_dummy /* Zones are obsolete. */
#else
static struct super_block super; /* Superblock of file system */
#define SUPER_V1 SUPER_MAGIC /* V1 magic has a weird name. */
#endif
static struct inode curfil; /* Inode of file under examination */
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static char indir[_MAX_BLOCK_SIZE]; /* Single indirect block. */
static char dindir[_MAX_BLOCK_SIZE]; /* Double indirect block. */
static char dirbuf[_MAX_BLOCK_SIZE]; /* Scratch/Directory block. */
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#define scratch dirbuf
static block_t a_indir, a_dindir; /* Addresses of the indirects. */
static off_t dirpos; /* Reading pos in a dir. */
#define fsbuf(b) (* (union fsdata_u *) (b))
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#define zone_shift (super.s_log_zone_size) /* zone to block ratio */
off_t r_super(int *bs)
/* Initialize variables, return size of file system in blocks,
* (zero on error).
*/
{
/* Read superblock. (The superblock is always at 1kB offset,
* that's why we lie to readblock and say the block size is 1024
* and we want block number 1 (the 'second block', at offset 1kB).)
*/
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readblock(1, scratch, 1024);
memcpy(&super, scratch, sizeof(super));
/* Is it really a MINIX file system ? */
if (super.s_magic == SUPER_V2 || super.s_magic == SUPER_V3) {
if(super.s_magic == SUPER_V2)
super.s_block_size = 1024;
*bs = block_size = super.s_block_size;
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if(block_size < _MIN_BLOCK_SIZE ||
block_size > _MAX_BLOCK_SIZE) {
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return 0;
}
nr_dzones= V2_NR_DZONES;
nr_indirects= V2_INDIRECTS(block_size);
inodes_per_block= V2_INODES_PER_BLOCK(block_size);
return (off_t) super.s_zones << zone_shift;
} else
if (super.s_magic == SUPER_V1) {
*bs = block_size = 1024;
nr_dzones= V1_NR_DZONES;
nr_indirects= V1_INDIRECTS;
inodes_per_block= V1_INODES_PER_BLOCK;
return (off_t) super.s_nzones << zone_shift;
} else {
/* Filesystem not recognized as Minix. */
return 0;
}
}
void r_stat(Ino_t inum, struct stat *stp)
/* Return information about a file like stat(2) and remember it. */
{
block_t block;
block_t ino_block;
ino_t ino_offset;
union fsdata_u *blockbuf;
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/* Calculate start of i-list */
block = START_BLOCK + super.s_imap_blocks + super.s_zmap_blocks;
/* Calculate block with inode inum */
ino_block = ((inum - 1) / inodes_per_block);
ino_offset = ((inum - 1) % inodes_per_block);
block += ino_block;
/* Fetch the block */
blockbuf = (union fsdata_u *) scratch;
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readblock(block, (char *) blockbuf, block_size);
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if (super.s_magic == SUPER_V2 || super.s_magic == SUPER_V3) {
d2_inode *dip;
int i;
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dip= &blockbuf->b__v2_ino[(unsigned int) ino_offset];
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curfil.i_mode= dip->d2_mode;
curfil.i_nlinks= dip->d2_nlinks;
curfil.i_uid= dip->d2_uid;
curfil.i_gid= dip->d2_gid;
curfil.i_size= dip->d2_size;
curfil.i_atime= dip->d2_atime;
curfil.i_mtime= dip->d2_mtime;
curfil.i_ctime= dip->d2_ctime;
for (i= 0; i < V2_NR_TZONES; i++)
curfil.i_zone[i]= dip->d2_zone[i];
} else {
d1_inode *dip;
int i;
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dip= &blockbuf->b__v1_ino[(unsigned int) ino_offset];
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curfil.i_mode= dip->d1_mode;
curfil.i_nlinks= dip->d1_nlinks;
curfil.i_uid= dip->d1_uid;
curfil.i_gid= dip->d1_gid;
curfil.i_size= dip->d1_size;
curfil.i_atime= dip->d1_mtime;
curfil.i_mtime= dip->d1_mtime;
curfil.i_ctime= dip->d1_mtime;
for (i= 0; i < V1_NR_TZONES; i++)
curfil.i_zone[i]= dip->d1_zone[i];
}
curfil.i_dev= -1; /* Can't fill this in alas. */
curfil.i_num= inum;
stp->st_dev= curfil.i_dev;
stp->st_ino= curfil.i_num;
stp->st_mode= curfil.i_mode;
stp->st_nlink= curfil.i_nlinks;
stp->st_uid= curfil.i_uid;
stp->st_gid= curfil.i_gid;
stp->st_rdev= (dev_t) curfil.i_zone[0];
stp->st_size= curfil.i_size;
stp->st_atime= curfil.i_atime;
stp->st_mtime= curfil.i_mtime;
stp->st_ctime= curfil.i_ctime;
a_indir= a_dindir= 0;
dirpos= 0;
}
ino_t r_readdir(char *name)
/* Read next directory entry at "dirpos" from file "curfil". */
{
ino_t inum= 0;
int blkpos;
struct direct *dp;
if (!S_ISDIR(curfil.i_mode)) { errno= ENOTDIR; return -1; }
if(!block_size) { errno = 0; return -1; }
while (inum == 0 && dirpos < curfil.i_size) {
if ((blkpos= (int) (dirpos % block_size)) == 0) {
/* Need to fetch a new directory block. */
readblock(r_vir2abs(dirpos / block_size), dirbuf, block_size);
}
#ifdef FLEX
if (super.s_flags & S_FLEX) {
struct _fl_direct *dp;
dp= (struct _fl_direct *) (dirbuf + blkpos);
if ((inum= dp->d_ino) != 0) strcpy(name, dp->d_name);
dirpos+= (1 + dp->d_extent) * FL_DIR_ENTRY_SIZE;
continue;
}
#endif
/* Let dp point to the next entry. */
dp= (struct direct *) (dirbuf + blkpos);
if ((inum= dp->d_ino) != 0) {
/* This entry is occupied, return name. */
strncpy(name, dp->d_name, sizeof(dp->d_name));
name[sizeof(dp->d_name)]= 0;
}
dirpos+= DIR_ENTRY_SIZE;
}
return inum;
}
off_t r_vir2abs(off_t virblk)
/* Translate a block number in a file to an absolute disk block number.
* Returns 0 for a hole and -1 if block is past end of file.
*/
{
block_t b= virblk;
zone_t zone, ind_zone;
block_t z, zone_index;
int i;
if(!block_size) return -1;
/* Check if virblk within file. */
if (virblk * block_size >= curfil.i_size) return -1;
/* Calculate zone in which the datablock number is contained */
zone = (zone_t) (b >> zone_shift);
/* Calculate index of the block number in the zone */
zone_index = b - ((block_t) zone << zone_shift);
/* Go get the zone */
if (zone < (zone_t) nr_dzones) { /* direct block */
zone = curfil.i_zone[(int) zone];
z = ((block_t) zone << zone_shift) + zone_index;
return z;
}
/* The zone is not a direct one */
zone -= (zone_t) nr_dzones;
/* Is it single indirect ? */
if (zone < (zone_t) nr_indirects) { /* single indirect block */
ind_zone = curfil.i_zone[nr_dzones];
} else { /* double indirect block */
/* Fetch the double indirect block */
if ((ind_zone = curfil.i_zone[nr_dzones + 1]) == 0) return 0;
z = (block_t) ind_zone << zone_shift;
if (a_dindir != z) {
readblock(z, dindir, block_size);
a_dindir= z;
}
/* Extract the indirect zone number from it */
zone -= (zone_t) nr_indirects;
i = zone / (zone_t) nr_indirects;
ind_zone = (super.s_magic == SUPER_V2 || super.s_magic == SUPER_V3)
? fsbuf(dindir).b__v2_ind[i]
: fsbuf(dindir).b__v1_ind[i];
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zone %= (zone_t) nr_indirects;
}
if (ind_zone == 0) return 0;
/* Extract the datablock number from the indirect zone */
z = (block_t) ind_zone << zone_shift;
if (a_indir != z) {
readblock(z, indir, block_size);
a_indir= z;
}
zone = (super.s_magic == SUPER_V2 || super.s_magic == SUPER_V3)
? fsbuf(indir).b__v2_ind[(int) zone]
: fsbuf(indir).b__v1_ind[(int) zone];
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/* Calculate absolute datablock number */
z = ((block_t) zone << zone_shift) + zone_index;
return z;
}
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ino_t r_lookup(Ino_t cwd, const char *path)
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/* Translates a pathname to an inode number. This is just a nice utility
* function, it only needs r_stat and r_readdir.
*/
{
char name[NAME_MAX+1], r_name[NAME_MAX+1];
char *n;
struct stat st;
ino_t ino;
ino= path[0] == '/' ? ROOT_INO : cwd;
for (;;) {
if (ino == 0) {
errno= ENOENT;
return 0;
}
while (*path == '/') path++;
if (*path == 0) return ino;
r_stat(ino, &st);
if (!S_ISDIR(st.st_mode)) {
errno= ENOTDIR;
return 0;
}
n= name;
while (*path != 0 && *path != '/')
if (n < name + NAME_MAX) *n++ = *path++;
*n= 0;
while ((ino= r_readdir(r_name)) != 0
&& strcmp(name, r_name) != 0) {
}
}
}
/*
* $PchId: rawfs.c,v 1.8 1999/11/05 23:14:15 philip Exp $
*/