root/fs/minix/namei.c

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DEFINITIONS

This source file includes following definitions.
  1. minix_match
  2. minix_find_entry
  3. minix_follow_link
  4. minix_lookup
  5. minix_add_entry
  6. minix_create
  7. minix_mknod
  8. minix_mkdir
  9. empty_dir
  10. minix_rmdir
  11. minix_unlink
  12. minix_symlink
  13. minix_link
  14. subdir
  15. do_minix_rename
  16. minix_rename
  17. minix_readlink

   1 /*
   2  *  linux/fs/minix/namei.c
   3  *
   4  *  (C) 1991  Linus Torvalds
   5  */
   6 
   7 #include <linux/sched.h>
   8 #include <linux/minix_fs.h>
   9 #include <linux/kernel.h>
  10 #include <asm/segment.h>
  11 
  12 #include <linux/string.h>
  13 #include <fcntl.h>
  14 #include <errno.h>
  15 #include <const.h>
  16 #include <sys/stat.h>
  17 
  18 /*
  19  * comment out this line if you want names > MINIX_NAME_LEN chars to be
  20  * truncated. Else they will be disallowed.
  21  */
  22 /* #define NO_TRUNCATE */
  23 
  24 /*
  25  * ok, we cannot use strncmp, as the name is not in our data space.
  26  * Thus we'll have to use minix_match. No big problem. Match also makes
  27  * some sanity tests.
  28  *
  29  * NOTE! unlike strncmp, minix_match returns 1 for success, 0 for failure.
  30  */
  31 static int minix_match(int len,const char * name,struct minix_dir_entry * de)
     /* [previous][next][first][last][top][bottom][index][help] */
  32 {
  33         register int same __asm__("ax");
  34 
  35         if (!de || !de->inode || len > MINIX_NAME_LEN)
  36                 return 0;
  37         /* "" means "." ---> so paths like "/usr/lib//libc.a" work */
  38         if (!len && (de->name[0]=='.') && (de->name[1]=='\0'))
  39                 return 1;
  40         if (len < MINIX_NAME_LEN && de->name[len])
  41                 return 0;
  42         __asm__("cld\n\t"
  43                 "fs ; repe ; cmpsb\n\t"
  44                 "setz %%al"
  45                 :"=a" (same)
  46                 :"0" (0),"S" ((long) name),"D" ((long) de->name),"c" (len)
  47                 :"cx","di","si");
  48         return same;
  49 }
  50 
  51 /*
  52  *      minix_find_entry()
  53  *
  54  * finds an entry in the specified directory with the wanted name. It
  55  * returns the cache buffer in which the entry was found, and the entry
  56  * itself (as a parameter - res_dir). It does NOT read the inode of the
  57  * entry - you'll have to do that yourself if you want to.
  58  */
  59 static struct buffer_head * minix_find_entry(struct inode * dir,
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  60         const char * name, int namelen, struct minix_dir_entry ** res_dir)
  61 {
  62         int entries;
  63         int block,i;
  64         struct buffer_head * bh;
  65         struct minix_dir_entry * de;
  66 
  67         *res_dir = NULL;
  68         if (!dir)
  69                 return NULL;
  70 #ifdef NO_TRUNCATE
  71         if (namelen > MINIX_NAME_LEN)
  72                 return NULL;
  73 #else
  74         if (namelen > MINIX_NAME_LEN)
  75                 namelen = MINIX_NAME_LEN;
  76 #endif
  77         entries = dir->i_size / (sizeof (struct minix_dir_entry));
  78         if (!(block = dir->i_data[0]))
  79                 return NULL;
  80         if (!(bh = bread(dir->i_dev,block)))
  81                 return NULL;
  82         i = 0;
  83         de = (struct minix_dir_entry *) bh->b_data;
  84         while (i < entries) {
  85                 if ((char *)de >= BLOCK_SIZE+bh->b_data) {
  86                         brelse(bh);
  87                         bh = NULL;
  88                         if (!(block = minix_bmap(dir,i/MINIX_DIR_ENTRIES_PER_BLOCK)) ||
  89                             !(bh = bread(dir->i_dev,block))) {
  90                                 i += MINIX_DIR_ENTRIES_PER_BLOCK;
  91                                 continue;
  92                         }
  93                         de = (struct minix_dir_entry *) bh->b_data;
  94                 }
  95                 if (minix_match(namelen,name,de)) {
  96                         *res_dir = de;
  97                         return bh;
  98                 }
  99                 de++;
 100                 i++;
 101         }
 102         brelse(bh);
 103         return NULL;
 104 }
 105 
 106 struct inode * minix_follow_link(struct inode * dir, struct inode * inode)
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 107 {
 108         unsigned short fs;
 109         struct buffer_head * bh;
 110 
 111         if (!dir) {
 112                 dir = current->root;
 113                 dir->i_count++;
 114         }
 115         if (!inode) {
 116                 iput(dir);
 117                 return NULL;
 118         }
 119         if (!S_ISLNK(inode->i_mode)) {
 120                 iput(dir);
 121                 return inode;
 122         }
 123         __asm__("mov %%fs,%0":"=r" (fs));
 124         if ((current->link_count > 5) || !inode->i_data[0] ||
 125            !(bh = bread(inode->i_dev, inode->i_data[0]))) {
 126                 iput(dir);
 127                 iput(inode);
 128                 return NULL;
 129         }
 130         iput(inode);
 131         __asm__("mov %0,%%fs"::"r" ((unsigned short) 0x10));
 132         current->link_count++;
 133         inode = _namei(bh->b_data,dir,1);
 134         current->link_count--;
 135         __asm__("mov %0,%%fs"::"r" (fs));
 136         brelse(bh);
 137         return inode;
 138 }
 139 
 140 int minix_lookup(struct inode * dir,const char * name, int len,
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 141         struct inode ** result)
 142 {
 143         int ino;
 144         struct minix_dir_entry * de;
 145         struct buffer_head * bh;
 146 
 147         *result = NULL;
 148         if (!dir)
 149                 return -ENOENT;
 150         if (!S_ISDIR(dir->i_mode)) {
 151                 iput(dir);
 152                 return -ENOENT;
 153         }
 154         if (!(bh = minix_find_entry(dir,name,len,&de))) {
 155                 iput(dir);
 156                 return -ENOENT;
 157         }
 158         ino = de->inode;
 159         brelse(bh);
 160         if (!(*result = iget(dir->i_dev,ino))) {
 161                 iput(dir);
 162                 return -EACCES;
 163         }
 164         iput(dir);
 165         return 0;
 166 }
 167 
 168 /*
 169  *      minix_add_entry()
 170  *
 171  * adds a file entry to the specified directory, using the same
 172  * semantics as minix_find_entry(). It returns NULL if it failed.
 173  *
 174  * NOTE!! The inode part of 'de' is left at 0 - which means you
 175  * may not sleep between calling this and putting something into
 176  * the entry, as someone else might have used it while you slept.
 177  */
 178 static struct buffer_head * minix_add_entry(struct inode * dir,
     /* [previous][next][first][last][top][bottom][index][help] */
 179         const char * name, int namelen, struct minix_dir_entry ** res_dir)
 180 {
 181         int block,i;
 182         struct buffer_head * bh;
 183         struct minix_dir_entry * de;
 184 
 185         *res_dir = NULL;
 186         if (!dir)
 187                 return NULL;
 188 #ifdef NO_TRUNCATE
 189         if (namelen > MINIX_NAME_LEN)
 190                 return NULL;
 191 #else
 192         if (namelen > MINIX_NAME_LEN)
 193                 namelen = MINIX_NAME_LEN;
 194 #endif
 195         if (!namelen)
 196                 return NULL;
 197         if (!(block = dir->i_data[0]))
 198                 return NULL;
 199         if (!(bh = bread(dir->i_dev,block)))
 200                 return NULL;
 201         i = 0;
 202         de = (struct minix_dir_entry *) bh->b_data;
 203         while (1) {
 204                 if ((char *)de >= BLOCK_SIZE+bh->b_data) {
 205                         brelse(bh);
 206                         bh = NULL;
 207                         block = minix_create_block(dir,i/MINIX_DIR_ENTRIES_PER_BLOCK);
 208                         if (!block)
 209                                 return NULL;
 210                         if (!(bh = bread(dir->i_dev,block))) {
 211                                 i += MINIX_DIR_ENTRIES_PER_BLOCK;
 212                                 continue;
 213                         }
 214                         de = (struct minix_dir_entry *) bh->b_data;
 215                 }
 216                 if (i*sizeof(struct minix_dir_entry) >= dir->i_size) {
 217                         de->inode=0;
 218                         dir->i_size = (i+1)*sizeof(struct minix_dir_entry);
 219                         dir->i_dirt = 1;
 220                         dir->i_ctime = CURRENT_TIME;
 221                 }
 222                 if (!de->inode) {
 223                         dir->i_mtime = CURRENT_TIME;
 224                         for (i=0; i < MINIX_NAME_LEN ; i++)
 225                                 de->name[i]=(i<namelen)?get_fs_byte(name+i):0;
 226                         bh->b_dirt = 1;
 227                         *res_dir = de;
 228                         return bh;
 229                 }
 230                 de++;
 231                 i++;
 232         }
 233         brelse(bh);
 234         return NULL;
 235 }
 236 
 237 int minix_create(struct inode * dir,const char * name, int len, int mode,
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 238         struct inode ** result)
 239 {
 240         struct inode * inode;
 241         struct buffer_head * bh;
 242         struct minix_dir_entry * de;
 243 
 244         *result = NULL;
 245         if (!dir)
 246                 return -ENOENT;
 247         inode = minix_new_inode(dir->i_dev);
 248         if (!inode) {
 249                 iput(dir);
 250                 return -ENOSPC;
 251         }
 252         inode->i_mode = mode;
 253         inode->i_dirt = 1;
 254         bh = minix_add_entry(dir,name,len,&de);
 255         if (!bh) {
 256                 inode->i_nlink--;
 257                 iput(inode);
 258                 iput(dir);
 259                 return -ENOSPC;
 260         }
 261         de->inode = inode->i_ino;
 262         bh->b_dirt = 1;
 263         brelse(bh);
 264         iput(dir);
 265         *result = inode;
 266         return 0;
 267 }
 268 
 269 int minix_mknod(struct inode * dir, const char * name, int len, int mode, int rdev)
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 270 {
 271         struct inode * inode;
 272         struct buffer_head * bh;
 273         struct minix_dir_entry * de;
 274 
 275         if (!dir)
 276                 return -ENOENT;
 277         bh = minix_find_entry(dir,name,len,&de);
 278         if (bh) {
 279                 brelse(bh);
 280                 iput(dir);
 281                 return -EEXIST;
 282         }
 283         inode = minix_new_inode(dir->i_dev);
 284         if (!inode) {
 285                 iput(dir);
 286                 return -ENOSPC;
 287         }
 288         inode->i_uid = current->euid;
 289         inode->i_mode = mode;
 290         if (S_ISBLK(mode) || S_ISCHR(mode))
 291                 inode->i_rdev = rdev;
 292         inode->i_mtime = inode->i_atime = CURRENT_TIME;
 293         inode->i_dirt = 1;
 294         bh = minix_add_entry(dir,name,len,&de);
 295         if (!bh) {
 296                 inode->i_nlink--;
 297                 iput(inode);
 298                 iput(dir);
 299                 return -ENOSPC;
 300         }
 301         de->inode = inode->i_ino;
 302         bh->b_dirt = 1;
 303         brelse(bh);
 304         iput(dir);
 305         iput(inode);
 306         return 0;
 307 }
 308 
 309 int minix_mkdir(struct inode * dir, const char * name, int len, int mode)
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 310 {
 311         struct inode * inode;
 312         struct buffer_head * bh, *dir_block;
 313         struct minix_dir_entry * de;
 314         
 315         bh = minix_find_entry(dir,name,len,&de);
 316         if (bh) {
 317                 brelse(bh);
 318                 iput(dir);
 319                 return -EEXIST;
 320         }
 321         inode = minix_new_inode(dir->i_dev);
 322         if (!inode) {
 323                 iput(dir);
 324                 return -ENOSPC;
 325         }
 326         inode->i_size = 2 * sizeof (struct minix_dir_entry);
 327         inode->i_dirt = 1;
 328         inode->i_mtime = inode->i_atime = CURRENT_TIME;
 329         if (!(inode->i_data[0] = minix_new_block(inode->i_dev))) {
 330                 iput(dir);
 331                 inode->i_nlink--;
 332                 iput(inode);
 333                 return -ENOSPC;
 334         }
 335         inode->i_dirt = 1;
 336         if (!(dir_block = bread(inode->i_dev,inode->i_data[0]))) {
 337                 iput(dir);
 338                 inode->i_nlink--;
 339                 iput(inode);
 340                 return -EIO;
 341         }
 342         de = (struct minix_dir_entry *) dir_block->b_data;
 343         de->inode=inode->i_ino;
 344         strcpy(de->name,".");
 345         de++;
 346         de->inode = dir->i_ino;
 347         strcpy(de->name,"..");
 348         inode->i_nlink = 2;
 349         dir_block->b_dirt = 1;
 350         brelse(dir_block);
 351         inode->i_mode = I_DIRECTORY | (mode & 0777 & ~current->umask);
 352         inode->i_dirt = 1;
 353         bh = minix_add_entry(dir,name,len,&de);
 354         if (!bh) {
 355                 iput(dir);
 356                 inode->i_nlink=0;
 357                 iput(inode);
 358                 return -ENOSPC;
 359         }
 360         de->inode = inode->i_ino;
 361         bh->b_dirt = 1;
 362         dir->i_nlink++;
 363         dir->i_dirt = 1;
 364         iput(dir);
 365         iput(inode);
 366         brelse(bh);
 367         return 0;
 368 }
 369 
 370 /*
 371  * routine to check that the specified directory is empty (for rmdir)
 372  */
 373 static int empty_dir(struct inode * inode)
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 374 {
 375         int nr,block;
 376         int len;
 377         struct buffer_head * bh;
 378         struct minix_dir_entry * de;
 379 
 380         len = inode->i_size / sizeof (struct minix_dir_entry);
 381         if (len<2 || !inode->i_data[0] ||
 382             !(bh=bread(inode->i_dev,inode->i_data[0]))) {
 383                 printk("warning - bad directory on dev %04x\n",inode->i_dev);
 384                 return 0;
 385         }
 386         de = (struct minix_dir_entry *) bh->b_data;
 387         if (de[0].inode != inode->i_ino || !de[1].inode || 
 388             strcmp(".",de[0].name) || strcmp("..",de[1].name)) {
 389                 printk("warning - bad directory on dev %04x\n",inode->i_dev);
 390                 return 0;
 391         }
 392         nr = 2;
 393         de += 2;
 394         while (nr<len) {
 395                 if ((void *) de >= (void *) (bh->b_data+BLOCK_SIZE)) {
 396                         brelse(bh);
 397                         block = minix_bmap(inode,nr/MINIX_DIR_ENTRIES_PER_BLOCK);
 398                         if (!block) {
 399                                 nr += MINIX_DIR_ENTRIES_PER_BLOCK;
 400                                 continue;
 401                         }
 402                         if (!(bh=bread(inode->i_dev,block)))
 403                                 return 0;
 404                         de = (struct minix_dir_entry *) bh->b_data;
 405                 }
 406                 if (de->inode) {
 407                         brelse(bh);
 408                         return 0;
 409                 }
 410                 de++;
 411                 nr++;
 412         }
 413         brelse(bh);
 414         return 1;
 415 }
 416 
 417 int minix_rmdir(struct inode * dir, const char * name, int len)
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 418 {
 419         int retval;
 420         struct inode * inode;
 421         struct buffer_head * bh;
 422         struct minix_dir_entry * de;
 423 
 424         inode = NULL;
 425         bh = minix_find_entry(dir,name,len,&de);
 426         retval = -ENOENT;
 427         if (!bh)
 428                 goto end_rmdir;
 429         retval = -EPERM;
 430         if (!(inode = iget(dir->i_dev, de->inode)))
 431                 goto end_rmdir;
 432         if ((dir->i_mode & S_ISVTX) && current->euid &&
 433            inode->i_uid != current->euid)
 434                 goto end_rmdir;
 435         if (inode->i_dev != dir->i_dev)
 436                 goto end_rmdir;
 437         if (inode == dir)       /* we may not delete ".", but "../dir" is ok */
 438                 goto end_rmdir;
 439         if (!S_ISDIR(inode->i_mode)) {
 440                 retval = -ENOTDIR;
 441                 goto end_rmdir;
 442         }
 443         if (!empty_dir(inode)) {
 444                 retval = -ENOTEMPTY;
 445                 goto end_rmdir;
 446         }
 447         if (inode->i_count > 1) {
 448                 retval = -EBUSY;
 449                 goto end_rmdir;
 450         }
 451         if (inode->i_nlink != 2)
 452                 printk("empty directory has nlink!=2 (%d)\n",inode->i_nlink);
 453         de->inode = 0;
 454         bh->b_dirt = 1;
 455         inode->i_nlink=0;
 456         inode->i_dirt=1;
 457         dir->i_nlink--;
 458         dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 459         dir->i_dirt=1;
 460         retval = 0;
 461 end_rmdir:
 462         iput(dir);
 463         iput(inode);
 464         brelse(bh);
 465         return retval;
 466 }
 467 
 468 int minix_unlink(struct inode * dir, const char * name, int len)
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 469 {
 470         int retval;
 471         struct inode * inode;
 472         struct buffer_head * bh;
 473         struct minix_dir_entry * de;
 474 
 475         retval = -ENOENT;
 476         inode = NULL;
 477         bh = minix_find_entry(dir,name,len,&de);
 478         if (!bh)
 479                 goto end_unlink;
 480         if (!(inode = iget(dir->i_dev, de->inode)))
 481                 goto end_unlink;
 482         retval = -EPERM;
 483         if ((dir->i_mode & S_ISVTX) && !suser() &&
 484             current->euid != inode->i_uid &&
 485             current->euid != dir->i_uid)
 486                 goto end_unlink;
 487         if (S_ISDIR(inode->i_mode))
 488                 goto end_unlink;
 489         if (!inode->i_nlink) {
 490                 printk("Deleting nonexistent file (%04x:%d), %d\n",
 491                         inode->i_dev,inode->i_ino,inode->i_nlink);
 492                 inode->i_nlink=1;
 493         }
 494         de->inode = 0;
 495         bh->b_dirt = 1;
 496         inode->i_nlink--;
 497         inode->i_dirt = 1;
 498         inode->i_ctime = CURRENT_TIME;
 499         retval = 0;
 500 end_unlink:
 501         brelse(bh);
 502         iput(inode);
 503         iput(dir);
 504         return retval;
 505 }
 506 
 507 int minix_symlink(struct inode * dir, const char * name, int len, const char * symname)
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 508 {
 509         struct minix_dir_entry * de;
 510         struct inode * inode = NULL;
 511         struct buffer_head * bh = NULL, * name_block = NULL;
 512         int i;
 513         char c;
 514 
 515         if (!(inode = minix_new_inode(dir->i_dev))) {
 516                 iput(dir);
 517                 return -ENOSPC;
 518         }
 519         inode->i_mode = S_IFLNK | 0777;
 520         inode->i_dirt = 1;
 521         if (!(inode->i_data[0] = minix_new_block(inode->i_dev))) {
 522                 iput(dir);
 523                 inode->i_nlink--;
 524                 iput(inode);
 525                 return -ENOSPC;
 526         }
 527         inode->i_dirt = 1;
 528         if (!(name_block = bread(inode->i_dev,inode->i_data[0]))) {
 529                 iput(dir);
 530                 inode->i_nlink--;
 531                 iput(inode);
 532                 return -EIO;
 533         }
 534         i = 0;
 535         while (i < 1023 && (c=get_fs_byte(symname++)))
 536                 name_block->b_data[i++] = c;
 537         name_block->b_data[i] = 0;
 538         name_block->b_dirt = 1;
 539         brelse(name_block);
 540         inode->i_size = i;
 541         inode->i_dirt = 1;
 542         bh = minix_find_entry(dir,name,len,&de);
 543         if (bh) {
 544                 inode->i_nlink--;
 545                 iput(inode);
 546                 brelse(bh);
 547                 iput(dir);
 548                 return -EEXIST;
 549         }
 550         bh = minix_add_entry(dir,name,len,&de);
 551         if (!bh) {
 552                 inode->i_nlink--;
 553                 iput(inode);
 554                 iput(dir);
 555                 return -ENOSPC;
 556         }
 557         de->inode = inode->i_ino;
 558         bh->b_dirt = 1;
 559         brelse(bh);
 560         iput(dir);
 561         iput(inode);
 562         return 0;
 563 }
 564 
 565 int minix_link(struct inode * oldinode, struct inode * dir, const char * name, int len)
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 566 {
 567         struct minix_dir_entry * de;
 568         struct buffer_head * bh;
 569 
 570         if (S_ISDIR(oldinode->i_mode)) {
 571                 iput(oldinode);
 572                 iput(dir);
 573                 return -EPERM;
 574         }
 575         bh = minix_find_entry(dir,name,len,&de);
 576         if (bh) {
 577                 brelse(bh);
 578                 iput(dir);
 579                 iput(oldinode);
 580                 return -EEXIST;
 581         }
 582         bh = minix_add_entry(dir,name,len,&de);
 583         if (!bh) {
 584                 iput(dir);
 585                 iput(oldinode);
 586                 return -ENOSPC;
 587         }
 588         de->inode = oldinode->i_ino;
 589         bh->b_dirt = 1;
 590         brelse(bh);
 591         iput(dir);
 592         oldinode->i_nlink++;
 593         oldinode->i_ctime = CURRENT_TIME;
 594         oldinode->i_dirt = 1;
 595         iput(oldinode);
 596         return 0;
 597 }
 598 
 599 static int subdir(struct inode * new, struct inode * old)
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 600 {
 601         unsigned short fs;
 602         int ino;
 603         int result;
 604 
 605         __asm__("mov %%fs,%0":"=r" (fs));
 606         __asm__("mov %0,%%fs"::"r" ((unsigned short) 0x10));
 607         new->i_count++;
 608         result = 0;
 609         for (;;) {
 610                 if (new == old) {
 611                         result = 1;
 612                         break;
 613                 }
 614                 if (new->i_dev != old->i_dev)
 615                         break;
 616                 ino = new->i_ino;
 617                 if (minix_lookup(new,"..",2,&new))
 618                         break;
 619                 if (new->i_ino == ino)
 620                         break;
 621         }
 622         iput(new);
 623         __asm__("mov %0,%%fs"::"r" (fs));
 624         return result;
 625 }
 626 
 627 #define PARENT_INO(buffer) \
 628 (((struct minix_dir_entry *) (buffer))[1].inode)
 629 
 630 #define PARENT_NAME(buffer) \
 631 (((struct minix_dir_entry *) (buffer))[1].name)
 632 
 633 /*
 634  * rename uses retrying to avoid race-conditions: at least they should be minimal.
 635  * it tries to allocate all the blocks, then sanity-checks, and if the sanity-
 636  * checks fail, it tries to restart itself again. Very practical - no changes
 637  * are done until we know everything works ok.. and then all the changes can be
 638  * done in one fell swoop when we have claimed all the buffers needed.
 639  *
 640  * Anybody can rename anything with this: the permission checks are left to the
 641  * higher-level routines.
 642  */
 643 static int do_minix_rename(struct inode * old_dir, const char * old_name, int old_len,
     /* [previous][next][first][last][top][bottom][index][help] */
 644         struct inode * new_dir, const char * new_name, int new_len)
 645 {
 646         struct inode * old_inode, * new_inode;
 647         struct buffer_head * old_bh, * new_bh, * dir_bh;
 648         struct minix_dir_entry * old_de, * new_de;
 649         int retval;
 650 
 651         goto start_up;
 652 try_again:
 653         brelse(old_bh);
 654         brelse(new_bh);
 655         brelse(dir_bh);
 656         iput(old_inode);
 657         iput(new_inode);
 658         current->counter = 0;
 659         schedule();
 660 start_up:
 661         old_inode = new_inode = NULL;
 662         old_bh = new_bh = dir_bh = NULL;
 663         old_bh = minix_find_entry(old_dir,old_name,old_len,&old_de);
 664         retval = -ENOENT;
 665         if (!old_bh)
 666                 goto end_rename;
 667         old_inode = iget(old_dir->i_dev, old_de->inode);
 668         if (!old_inode)
 669                 goto end_rename;
 670         new_bh = minix_find_entry(new_dir,new_name,new_len,&new_de);
 671         if (new_bh) {
 672                 new_inode = iget(new_dir->i_dev, new_de->inode);
 673                 if (!new_inode) {
 674                         brelse(new_bh);
 675                         new_bh = NULL;
 676                 }
 677         }
 678         if (new_inode == old_inode) {
 679                 retval = 0;
 680                 goto end_rename;
 681         }
 682         if (S_ISDIR(old_inode->i_mode)) {
 683                 retval = -EEXIST;
 684                 if (new_bh)
 685                         goto end_rename;
 686                 retval = -EACCES;
 687                 if (!permission(old_inode, MAY_WRITE))
 688                         goto end_rename;
 689                 retval = -EINVAL;
 690                 if (subdir(new_dir, old_inode))
 691                         goto end_rename;
 692                 retval = -EIO;
 693                 if (!old_inode->i_data[0])
 694                         goto end_rename;
 695                 if (!(dir_bh = bread(old_inode->i_dev, old_inode->i_data[0])))
 696                         goto end_rename;
 697                 if (PARENT_INO(dir_bh->b_data) != old_dir->i_ino)
 698                         goto end_rename;
 699         }
 700         if (!new_bh)
 701                 new_bh = minix_add_entry(new_dir,new_name,new_len,&new_de);
 702         retval = -ENOSPC;
 703         if (!new_bh)
 704                 goto end_rename;
 705 /* sanity checking before doing the rename - avoid races */
 706         if (new_inode && (new_de->inode != new_inode->i_ino))
 707                 goto try_again;
 708         if (new_de->inode && !new_inode)
 709                 goto try_again;
 710         if (old_de->inode != old_inode->i_ino)
 711                 goto try_again;
 712 /* ok, that's it */
 713         old_de->inode = 0;
 714         new_de->inode = old_inode->i_ino;
 715         if (new_inode)
 716                 new_inode->i_nlink--;
 717         old_bh->b_dirt = 1;
 718         new_bh->b_dirt = 1;
 719         if (dir_bh) {
 720                 PARENT_INO(dir_bh->b_data) = new_dir->i_ino;
 721                 dir_bh->b_dirt = 1;
 722                 old_dir->i_nlink--;
 723                 new_dir->i_nlink++;
 724                 old_dir->i_dirt = 1;
 725                 new_dir->i_dirt = 1;
 726         }
 727         retval = 0;
 728 end_rename:
 729         brelse(dir_bh);
 730         brelse(old_bh);
 731         brelse(new_bh);
 732         iput(old_inode);
 733         iput(new_inode);
 734         iput(old_dir);
 735         iput(new_dir);
 736         return retval;
 737 }
 738 
 739 /*
 740  * Ok, rename also locks out other renames, as they can change the parent of
 741  * a directory, and we don't want any races. Other races are checked for by
 742  * "do_rename()", which restarts if there are inconsistencies.
 743  *
 744  * Note that there is no race between different filesystems: it's only within
 745  * the same device that races occur: many renames can happen at once, as long
 746  * as they are on different partitions.
 747  */
 748 int minix_rename(struct inode * old_dir, const char * old_name, int old_len,
     /* [previous][next][first][last][top][bottom][index][help] */
 749         struct inode * new_dir, const char * new_name, int new_len)
 750 {
 751         static struct task_struct * wait = NULL;
 752         static int lock = 0;
 753         int result;
 754 
 755         while (lock)
 756                 sleep_on(&wait);
 757         lock = 1;
 758         result = do_minix_rename(old_dir, old_name, old_len,
 759                 new_dir, new_name, new_len);
 760         lock = 0;
 761         wake_up(&wait);
 762         return result;
 763 }
 764 
 765 int minix_readlink(struct inode * inode, char * buffer, int buflen)
     /* [previous][next][first][last][top][bottom][index][help] */
 766 {
 767         struct buffer_head * bh;
 768         int i;
 769         char c;
 770 
 771         if (!S_ISLNK(inode->i_mode)) {
 772                 iput(inode);
 773                 return -EINVAL;
 774         }
 775         if (buflen > 1023)
 776                 buflen = 1023;
 777         if (inode->i_data[0])
 778                 bh = bread(inode->i_dev, inode->i_data[0]);
 779         else
 780                 bh = NULL;
 781         iput(inode);
 782         if (!bh)
 783                 return 0;
 784         i = 0;
 785         while (i<buflen && (c = bh->b_data[i])) {
 786                 i++;
 787                 put_fs_byte(c,buffer++);
 788         }
 789         brelse(bh);
 790         return i;
 791 }

/* [previous][next][first][last][top][bottom][index][help] */