boot/rawfs.c

   1 /*      rawfs.c - Raw Minix file system support.        Author: Kees J. Bot
   2  *                                                              23 Dec 1991
   3  *                                           Based on readfs by Paul Polderman
   4  */
   5 #define nil 0
   6 #define _POSIX_SOURCE   1
   7 #define _MINIX          1
   8 #include <sys/types.h>
   9 #include <sys/stat.h>
  10 #include <stdlib.h>
  11 #include <limits.h>
  12 #include <string.h>
  13 #include <errno.h>
  14 #include <minix/config.h>
  15 #include <minix/const.h>
  16 #include <minix/type.h>
  17 #include <servers/fs/const.h>
  18 #include <servers/fs/type.h>
  19 #include <servers/fs/buf.h>
  20 #include <servers/fs/super.h>
  21 #include <servers/fs/inode.h>
  22 #include "rawfs.h"
  23
  24 void readblock(off_t blockno, char *buf, int);
  25
  26 /* The following code handles two file system types: Version 1 with small
  27  * inodes and 16-bit disk addresses and Version 2 with big inodes and 32-bit
  28  * disk addresses.
  29 #ifdef FLEX
  30  * To make matters worse, Minix-vmd knows about the normal Unix Version 7
  31  * directories and directories with flexible entries.
  32 #endif
  33  */
  34
  35 /* File system parameters. */
  36 static unsigned nr_dzones;      /* Fill these in after reading superblock. */
  37 static unsigned nr_indirects;
  38 static unsigned inodes_per_block;
  39 static int block_size;
  40 #ifdef FLEX
  41 #include <dirent.h>
  42 #define direct _v7_direct
  43 #else
  44 #include <sys/dir.h>
  45 #endif
  46
  47 #if __minix_vmd
  48 static struct v12_super_block super;    /* Superblock of file system */
  49 #define s_log_zone_size s_dummy         /* Zones are obsolete. */
  50 #else
  51 static struct super_block super;        /* Superblock of file system */
  52 #define SUPER_V1 SUPER_MAGIC            /* V1 magic has a weird name. */
  53 #endif
  54
  55 static struct inode curfil;             /* Inode of file under examination */
  56 static char indir[_MAX_BLOCK_SIZE];     /* Single indirect block. */
  57 static char dindir[_MAX_BLOCK_SIZE];    /* Double indirect block. */
  58 static char dirbuf[_MAX_BLOCK_SIZE];    /* Scratch/Directory block. */
  59 #define scratch dirbuf
  60
  61 static block_t a_indir, a_dindir;       /* Addresses of the indirects. */
  62 static off_t dirpos;                    /* Reading pos in a dir. */
  63
  64 #define fsbuf(b)        (* (struct buf *) (b))
  65
  66 #define zone_shift      (super.s_log_zone_size) /* zone to block ratio */
  67
  68 off_t r_super(int *bs)
  69 /* Initialize variables, return size of file system in blocks,
  70  * (zero on error).
  71  */
  72 {
  73         /* Read superblock. (The superblock is always at 1kB offset,
  74          * that's why we lie to readblock and say the block size is 1024
  75          * and we want block number 1 (the 'second block', at offset 1kB).)
  76          */
  77         readblock(1, scratch, 1024);
  78
  79         memcpy(&super, scratch, sizeof(super));
  80
  81         /* Is it really a MINIX file system ? */
  82         if (super.s_magic == SUPER_V2 || super.s_magic == SUPER_V3) {
  83                 if(super.s_magic == SUPER_V2)
  84                         super.s_block_size = 1024;
  85                 *bs = block_size = super.s_block_size;
  86                 if(block_size < _MIN_BLOCK_SIZE ||
  87                         block_size > _MAX_BLOCK_SIZE) {
  88                         return 0;
  89                 }
  90                 nr_dzones= V2_NR_DZONES;
  91                 nr_indirects= V2_INDIRECTS(block_size);
  92                 inodes_per_block= V2_INODES_PER_BLOCK(block_size);
  93                 return (off_t) super.s_zones << zone_shift;
  94         } else
  95         if (super.s_magic == SUPER_V1) {
  96                 *bs = block_size = 1024;
  97                 nr_dzones= V1_NR_DZONES;
  98                 nr_indirects= V1_INDIRECTS;
  99                 inodes_per_block= V1_INODES_PER_BLOCK;
 100                 return (off_t) super.s_nzones << zone_shift;
 101         } else {
 102                 /* Filesystem not recognized as Minix. */
 103                 return 0;
 104         }
 105 }
 106
 107 void r_stat(Ino_t inum, struct stat *stp)
 108 /* Return information about a file like stat(2) and remember it. */
 109 {
 110         block_t block;
 111         block_t ino_block;
 112         ino_t ino_offset;
 113
 114         /* Calculate start of i-list */
 115         block = START_BLOCK + super.s_imap_blocks + super.s_zmap_blocks;
 116
 117         /* Calculate block with inode inum */
 118         ino_block = ((inum - 1) / inodes_per_block);
 119         ino_offset = ((inum - 1) % inodes_per_block);
 120         block += ino_block;
 121
 122         /* Fetch the block */
 123         readblock(block, scratch, block_size);
 124
 125         if (super.s_magic == SUPER_V2 || super.s_magic == SUPER_V3) {
 126                 d2_inode *dip;
 127                 int i;
 128
 129                 dip= &fsbuf(scratch).b_v2_ino[ino_offset];
 130
 131                 curfil.i_mode= dip->d2_mode;
 132                 curfil.i_nlinks= dip->d2_nlinks;
 133                 curfil.i_uid= dip->d2_uid;
 134                 curfil.i_gid= dip->d2_gid;
 135                 curfil.i_size= dip->d2_size;
 136                 curfil.i_atime= dip->d2_atime;
 137                 curfil.i_mtime= dip->d2_mtime;
 138                 curfil.i_ctime= dip->d2_ctime;
 139                 for (i= 0; i < V2_NR_TZONES; i++)
 140                         curfil.i_zone[i]= dip->d2_zone[i];
 141         } else {
 142                 d1_inode *dip;
 143                 int i;
 144
 145                 dip= &fsbuf(scratch).b_v1_ino[ino_offset];
 146
 147                 curfil.i_mode= dip->d1_mode;
 148                 curfil.i_nlinks= dip->d1_nlinks;
 149                 curfil.i_uid= dip->d1_uid;
 150                 curfil.i_gid= dip->d1_gid;
 151                 curfil.i_size= dip->d1_size;
 152                 curfil.i_atime= dip->d1_mtime;
 153                 curfil.i_mtime= dip->d1_mtime;
 154                 curfil.i_ctime= dip->d1_mtime;
 155                 for (i= 0; i < V1_NR_TZONES; i++)
 156                         curfil.i_zone[i]= dip->d1_zone[i];
 157         }
 158         curfil.i_dev= -1;       /* Can't fill this in alas. */
 159         curfil.i_num= inum;
 160
 161         stp->st_dev= curfil.i_dev;
 162         stp->st_ino= curfil.i_num;
 163         stp->st_mode= curfil.i_mode;
 164         stp->st_nlink= curfil.i_nlinks;
 165         stp->st_uid= curfil.i_uid;
 166         stp->st_gid= curfil.i_gid;
 167         stp->st_rdev= (dev_t) curfil.i_zone[0];
 168         stp->st_size= curfil.i_size;
 169         stp->st_atime= curfil.i_atime;
 170         stp->st_mtime= curfil.i_mtime;
 171         stp->st_ctime= curfil.i_ctime;
 172
 173         a_indir= a_dindir= 0;
 174         dirpos= 0;
 175 }
 176
 177 ino_t r_readdir(char *name)
 178 /* Read next directory entry at "dirpos" from file "curfil". */
 179 {
 180         ino_t inum= 0;
 181         int blkpos;
 182         struct direct *dp;
 183
 184         if (!S_ISDIR(curfil.i_mode)) { errno= ENOTDIR; return -1; }
 185
 186         if(!block_size) { errno = 0; return -1; }
 187
 188         while (inum == 0 && dirpos < curfil.i_size) {
 189                 if ((blkpos= (int) (dirpos % block_size)) == 0) {
 190                         /* Need to fetch a new directory block. */
 191
 192                         readblock(r_vir2abs(dirpos / block_size), dirbuf, block_size);
 193                 }
 194 #ifdef FLEX
 195                 if (super.s_flags & S_FLEX) {
 196                         struct _fl_direct *dp;
 197
 198                         dp= (struct _fl_direct *) (dirbuf + blkpos);
 199                         if ((inum= dp->d_ino) != 0) strcpy(name, dp->d_name);
 200
 201                         dirpos+= (1 + dp->d_extent) * FL_DIR_ENTRY_SIZE;
 202                         continue;
 203                 }
 204 #endif
 205                 /* Let dp point to the next entry. */
 206                 dp= (struct direct *) (dirbuf + blkpos);
 207
 208                 if ((inum= dp->d_ino) != 0) {
 209                         /* This entry is occupied, return name. */
 210                         strncpy(name, dp->d_name, sizeof(dp->d_name));
 211                         name[sizeof(dp->d_name)]= 0;
 212                 }
 213                 dirpos+= DIR_ENTRY_SIZE;
 214         }
 215         return inum;
 216 }
 217
 218 off_t r_vir2abs(off_t virblk)
 219 /* Translate a block number in a file to an absolute disk block number.
 220  * Returns 0 for a hole and -1 if block is past end of file.
 221  */
 222 {
 223         block_t b= virblk;
 224         zone_t zone, ind_zone;
 225         block_t z, zone_index;
 226         int i;
 227
 228         if(!block_size) return -1;
 229
 230         /* Check if virblk within file. */
 231         if (virblk * block_size >= curfil.i_size) return -1;
 232
 233         /* Calculate zone in which the datablock number is contained */
 234         zone = (zone_t) (b >> zone_shift);
 235
 236         /* Calculate index of the block number in the zone */
 237         zone_index = b - ((block_t) zone << zone_shift);
 238
 239         /* Go get the zone */
 240         if (zone < (zone_t) nr_dzones) {        /* direct block */
 241                 zone = curfil.i_zone[(int) zone];
 242                 z = ((block_t) zone << zone_shift) + zone_index;
 243                 return z;
 244         }
 245
 246         /* The zone is not a direct one */
 247         zone -= (zone_t) nr_dzones;
 248
 249         /* Is it single indirect ? */
 250         if (zone < (zone_t) nr_indirects) {     /* single indirect block */
 251                 ind_zone = curfil.i_zone[nr_dzones];
 252         } else {                        /* double indirect block */
 253                 /* Fetch the double indirect block */
 254                 if ((ind_zone = curfil.i_zone[nr_dzones + 1]) == 0) return 0;
 255
 256                 z = (block_t) ind_zone << zone_shift;
 257                 if (a_dindir != z) {
 258                         readblock(z, dindir, block_size);
 259                         a_dindir= z;
 260                 }
 261                 /* Extract the indirect zone number from it */
 262                 zone -= (zone_t) nr_indirects;
 263
 264                 i = zone / (zone_t) nr_indirects;
 265                 ind_zone = (super.s_magic == SUPER_V2 || super.s_magic == SUPER_V3)
 266                                 ? fsbuf(dindir).b_v2_ind[i]
 267                                 : fsbuf(dindir).b_v1_ind[i];
 268                 zone %= (zone_t) nr_indirects;
 269         }
 270         if (ind_zone == 0) return 0;
 271
 272         /* Extract the datablock number from the indirect zone */
 273         z = (block_t) ind_zone << zone_shift;
 274         if (a_indir != z) {
 275                 readblock(z, indir, block_size);
 276                 a_indir= z;
 277         }
 278         zone = (super.s_magic == SUPER_V2 || super.s_magic == SUPER_V3)
 279                 ? fsbuf(indir).b_v2_ind[(int) zone]
 280                 : fsbuf(indir).b_v1_ind[(int) zone];
 281
 282         /* Calculate absolute datablock number */
 283         z = ((block_t) zone << zone_shift) + zone_index;
 284         return z;
 285 }
 286
 287 ino_t r_lookup(Ino_t cwd, char *path)
 288 /* Translates a pathname to an inode number.  This is just a nice utility
 289  * function, it only needs r_stat and r_readdir.
 290  */
 291 {
 292         char name[NAME_MAX+1], r_name[NAME_MAX+1];
 293         char *n;
 294         struct stat st;
 295         ino_t ino;
 296
 297         ino= path[0] == '/' ? ROOT_INO : cwd;
 298
 299         for (;;) {
 300                 if (ino == 0) {
 301                         errno= ENOENT;
 302                         return 0;
 303                 }
 304
 305                 while (*path == '/') path++;
 306
 307                 if (*path == 0) return ino;
 308
 309                 r_stat(ino, &st);
 310
 311                 if (!S_ISDIR(st.st_mode)) {
 312                         errno= ENOTDIR;
 313                         return 0;
 314                 }
 315
 316                 n= name;
 317                 while (*path != 0 && *path != '/')
 318                         if (n < name + NAME_MAX) *n++ = *path++;
 319                 *n= 0;
 320
 321                 while ((ino= r_readdir(r_name)) != 0
 322                                         && strcmp(name, r_name) != 0) {
 323                 }
 324         }
 325 }
 326
 327 /*
 328  * $PchId: rawfs.c,v 1.8 1999/11/05 23:14:15 philip Exp $
 329  */