fs/ext/namei.c

/* */
This source file includes following definitions.
ext_match
ext_find_entry
ext_lookup
ext_add_entry
ext_create
ext_mknod
ext_mkdir
empty_dir
ext_merge_entries
ext_rmdir
ext_unlink
ext_symlink
ext_link
subdir
do_ext_rename
ext_rename
   1 /*
   2  *  linux/fs/ext/namei.c
   3  *
   4  *  Copyright (C) 1992  Remy Card (card@masi.ibp.fr)
   5  *
   6  *  from
   7  *
   8  *  linux/fs/minix/namei.c
   9  *
  10  *  Copyright (C) 1991, 1992  Linus Torvalds
  11  */
  12 
  13 #include <linux/sched.h>
  14 #include <linux/ext_fs.h>
  15 #include <linux/kernel.h>
  16 #include <linux/string.h>
  17 #include <linux/stat.h>
  18 #include <linux/fcntl.h>
  19 #include <linux/errno.h>
  20 
  21 #include <asm/segment.h>
  22 
  23 /*
  24  * comment out this line if you want names > EXT_NAME_LEN chars to be
  25  * truncated. Else they will be disallowed.
  26  */
  27 /* #define NO_TRUNCATE */
  28 
  29 /*
  30  * EXT_DIR_PAD defines the directory entries boundaries
  31  *
  32  * NOTE: It must be a power of 2 and must be greater or equal than 8
  33  * because a directory entry needs 8 bytes for its fixed part
  34  * (4 bytes for the inode, 2 bytes for the entry length and 2 bytes
  35  * for the name length)
  36  */
  37 #define EXT_DIR_PAD 8
  38 
  39 /*
  40  *
  41  * EXT_DIR_MIN_SIZE is the minimal size of a directory entry
  42  *
  43  * During allocations, a directory entry is split into 2 ones
  44  * *ONLY* if the size of the unused part is greater than or 
  45  * equal to EXT_DIR_MIN_SIZE
  46  */
  47 #define EXT_DIR_MIN_SIZE 12
  48 
  49 /*
  50  * ok, we cannot use strncmp, as the name is not in our data space.
  51  * Thus we'll have to use ext_match. No big problem. Match also makes
  52  * some sanity tests.
  53  *
  54  * NOTE! unlike strncmp, ext_match returns 1 for success, 0 for failure.
  55  */
  56 static int ext_match(int len,const char * name,struct ext_dir_entry * de)
     /*  */
  57 {
  58         if (!de || !de->inode || len > EXT_NAME_LEN)
  59                 return 0;
  60         /* "" means "." ---> so paths like "/usr/lib//libc.a" work */
  61         if (!len && (de->name[0]=='.') && (de->name[1]=='\0'))
  62                 return 1;
  63         if (len != de->name_len)
  64                 return 0;
  65         return !memcmp(name, de->name, len);
  66 }
  67 
  68 /*
  69  *      ext_find_entry()
  70  *
  71  * finds an entry in the specified directory with the wanted name. It
  72  * returns the cache buffer in which the entry was found, and the entry
  73  * itself (as a parameter - res_dir). It does NOT read the inode of the
  74  * entry - you'll have to do that yourself if you want to.
  75  *
  76  * addition for the ext file system : this function returns the previous
  77  * and next directory entries in the parameters prev_dir and next_dir
  78  */
  79 static struct buffer_head * ext_find_entry(struct inode * dir,
     /*  */
  80         const char * name, int namelen, struct ext_dir_entry ** res_dir,
  81         struct ext_dir_entry ** prev_dir, struct ext_dir_entry ** next_dir)
  82 {
  83         long offset;
  84         struct buffer_head * bh;
  85         struct ext_dir_entry * de;
  86 
  87         *res_dir = NULL;
  88         if (!dir)
  89                 return NULL;
  90 #ifdef NO_TRUNCATE
  91         if (namelen > EXT_NAME_LEN)
  92                 return NULL;
  93 #else
  94         if (namelen > EXT_NAME_LEN)
  95                 namelen = EXT_NAME_LEN;
  96 #endif
  97         bh = ext_bread(dir,0,0);
  98         if (!bh)
  99                 return NULL;
 100         if (prev_dir)
 101                 *prev_dir = NULL;
 102         if (next_dir)
 103                 *next_dir = NULL;
 104         offset = 0;
 105         de = (struct ext_dir_entry *) bh->b_data;
 106         while (offset < dir->i_size) {
 107                 if ((char *)de >= BLOCK_SIZE+bh->b_data) {
 108                         brelse(bh);
 109                         bh = NULL;
 110                         bh = ext_bread(dir,offset>>BLOCK_SIZE_BITS,0);
 111                         if (!bh)
 112                                 continue;
 113                         de = (struct ext_dir_entry *) bh->b_data;
 114                         if (prev_dir)
 115                                 *prev_dir = NULL;
 116                 }
 117                 if (de->rec_len < 8 || de->rec_len % 8 != 0 ||
 118                     de->rec_len < de->name_len + 8 ||
 119                     (((char *) de) + de->rec_len-1 >= BLOCK_SIZE+bh->b_data)) {
 120                         printk ("ext_find_entry: bad dir entry\n");
 121                         printk ("dev=%d, dir=%ld, offset=%ld, rec_len=%d, name_len=%d\n",
 122                                 dir->i_dev, dir->i_ino, offset, de->rec_len, de->name_len);
 123                         de = (struct ext_dir_entry *) (bh->b_data+BLOCK_SIZE);
 124                         offset = ((offset / BLOCK_SIZE) + 1) * BLOCK_SIZE;
 125                         continue;
 126 /*                      brelse (bh);
 127                         return NULL; */
 128                 }
 129                 if (ext_match(namelen,name,de)) {
 130                         *res_dir = de;
 131                         if (next_dir)
 132                                 if (offset + de->rec_len < dir->i_size &&
 133                                     ((char *)de) + de->rec_len < BLOCK_SIZE+bh->b_data)
 134                                         *next_dir = (struct ext_dir_entry *)
 135                                                 ((char *) de + de->rec_len);
 136                                 else
 137                                         *next_dir = NULL;
 138                         return bh;
 139                 }
 140                 offset += de->rec_len;
 141                 if (prev_dir)
 142                         *prev_dir = de;
 143                 de = (struct ext_dir_entry *) ((char *) de + de->rec_len);
 144         }
 145         brelse(bh);
 146         return NULL;
 147 }
 148 
 149 int ext_lookup(struct inode * dir,const char * name, int len,
     /*  */
 150         struct inode ** result)
 151 {
 152         int ino;
 153         struct ext_dir_entry * de;
 154         struct buffer_head * bh;
 155 
 156         *result = NULL;
 157         if (!dir)
 158                 return -ENOENT;
 159         if (!S_ISDIR(dir->i_mode)) {
 160                 iput(dir);
 161                 return -ENOENT;
 162         }
 163         if (!(bh = ext_find_entry(dir,name,len,&de,NULL,NULL))) {
 164                 iput(dir);
 165                 return -ENOENT;
 166         }
 167         ino = de->inode;
 168         brelse(bh);
 169         if (!(*result = iget(dir->i_sb,ino))) {
 170                 iput(dir);
 171                 return -EACCES;
 172         }
 173         iput(dir);
 174         return 0;
 175 }
 176 
 177 /*
 178  *      ext_add_entry()
 179  *
 180  * adds a file entry to the specified directory, using the same
 181  * semantics as ext_find_entry(). It returns NULL if it failed.
 182  *
 183  * NOTE!! The inode part of 'de' is left at 0 - which means you
 184  * may not sleep between calling this and putting something into
 185  * the entry, as someone else might have used it while you slept.
 186  */
 187 static struct buffer_head * ext_add_entry(struct inode * dir,
     /*  */
 188         const char * name, int namelen, struct ext_dir_entry ** res_dir)
 189 {
 190         int i;
 191         long offset;
 192         unsigned short rec_len;
 193         struct buffer_head * bh;
 194         struct ext_dir_entry * de, * de1;
 195 
 196         *res_dir = NULL;
 197         if (!dir)
 198                 return NULL;
 199 #ifdef NO_TRUNCATE
 200         if (namelen > EXT_NAME_LEN)
 201                 return NULL;
 202 #else
 203         if (namelen > EXT_NAME_LEN)
 204                 namelen = EXT_NAME_LEN;
 205 #endif
 206         if (!namelen)
 207                 return NULL;
 208         bh = ext_bread(dir,0,0);
 209         if (!bh)
 210                 return NULL;
 211         rec_len = ((8 + namelen + EXT_DIR_PAD - 1) / EXT_DIR_PAD) * EXT_DIR_PAD;
 212         offset = 0;
 213         de = (struct ext_dir_entry *) bh->b_data;
 214         while (1) {
 215                 if ((char *)de >= BLOCK_SIZE+bh->b_data && offset < dir->i_size) {
 216 #ifdef EXTFS_DEBUG
 217 printk ("ext_add_entry: skipping to next block\n");
 218 #endif
 219                         brelse(bh);
 220                         bh = NULL;
 221                         bh = ext_bread(dir,offset>>BLOCK_SIZE_BITS,0);
 222                         if (!bh)
 223                                 return NULL;
 224                         de = (struct ext_dir_entry *) bh->b_data;
 225                 }
 226                 if (offset >= dir->i_size) {
 227                         /* Check that the directory entry fits in the block */
 228                         if (offset % BLOCK_SIZE == 0  ||
 229                             (BLOCK_SIZE - (offset % BLOCK_SIZE)) < rec_len) {
 230                                 if ((offset % BLOCK_SIZE) != 0) {
 231                                         /* If the entry does not fit in the
 232                                            block, the remainder of the block
 233                                            becomes an unused entry */
 234                                         de->inode = 0;
 235                                         de->rec_len = BLOCK_SIZE
 236                                                 - (offset & (BLOCK_SIZE - 1));
 237                                         de->name_len = 0;
 238                                         offset += de->rec_len;
 239                                         dir->i_size += de->rec_len;
 240                                         dir->i_dirt = 1;
 241 #if 0
 242                                         dir->i_ctime = CURRENT_TIME;
 243 #endif
 244                                         mark_buffer_dirty(bh, 1);
 245                                 }
 246                                 brelse (bh);
 247                                 bh = NULL;
 248 #ifdef EXTFS_DEBUG
 249 printk ("ext_add_entry : creating next block\n");
 250 #endif
 251                                 bh = ext_bread(dir,offset>>BLOCK_SIZE_BITS,1);
 252                                 if (!bh)
 253                                         return NULL; /* Other thing to do ??? */
 254                                 de = (struct ext_dir_entry *) bh->b_data;
 255                         }
 256                         /* Allocate the entry */
 257                         de->inode=0;
 258                         de->rec_len = rec_len;
 259                         dir->i_size += de->rec_len;
 260                         dir->i_dirt = 1;
 261 #if 0
 262                         dir->i_ctime = CURRENT_TIME;
 263 #endif
 264                 }
 265                 if (de->rec_len < 8 || de->rec_len % 4 != 0 ||
 266                     de->rec_len < de->name_len + 8 ||
 267                     (((char *) de) + de->rec_len-1 >= BLOCK_SIZE+bh->b_data)) {
 268                         printk ("ext_addr_entry: bad dir entry\n");
 269                         printk ("dev=%d, dir=%ld, offset=%ld, rec_len=%d, name_len=%d\n",
 270                                 dir->i_dev, dir->i_ino, offset, de->rec_len, de->name_len);
 271                         brelse (bh);
 272                         return NULL;
 273                 }
 274                 if (!de->inode && de->rec_len >= rec_len) {
 275                         if (de->rec_len > rec_len
 276                             && de->rec_len - rec_len >= EXT_DIR_MIN_SIZE) {
 277                                 /* The found entry is too big : it is split
 278                                    into 2 ones :
 279                                    - the 1st one will be used to hold the name,
 280                                    - the 2nd one is unused */
 281                                 de1 = (struct ext_dir_entry *) ((char *) de + rec_len);
 282                                 de1->inode = 0;
 283                                 de1->rec_len = de->rec_len - rec_len;
 284                                 de1->name_len = 0;
 285                                 de->rec_len = rec_len;
 286                         }
 287                         dir->i_mtime = dir->i_ctime = CURRENT_TIME;
 288                         de->name_len = namelen;
 289                         for (i=0; i < namelen ; i++)
 290                                 de->name[i] = name[i];
 291                         mark_buffer_dirty(bh, 1);
 292                         *res_dir = de;
 293                         return bh;
 294                 }
 295                 offset += de->rec_len;
 296                 de = (struct ext_dir_entry *) ((char *) de + de->rec_len);
 297         }
 298         brelse(bh);
 299         return NULL;
 300 }
 301 
 302 int ext_create(struct inode * dir,const char * name, int len, int mode,
     /*  */
 303         struct inode ** result)
 304 {
 305         struct inode * inode;
 306         struct buffer_head * bh;
 307         struct ext_dir_entry * de;
 308 
 309         *result = NULL;
 310         if (!dir)
 311                 return -ENOENT;
 312         inode = ext_new_inode(dir);
 313         if (!inode) {
 314                 iput(dir);
 315                 return -ENOSPC;
 316         }
 317         inode->i_op = &ext_file_inode_operations;
 318         inode->i_mode = mode;
 319         inode->i_dirt = 1;
 320         bh = ext_add_entry(dir,name,len,&de);
 321         if (!bh) {
 322                 inode->i_nlink--;
 323                 inode->i_dirt = 1;
 324                 iput(inode);
 325                 iput(dir);
 326                 return -ENOSPC;
 327         }
 328         de->inode = inode->i_ino;
 329         mark_buffer_dirty(bh, 1);
 330         brelse(bh);
 331         iput(dir);
 332         *result = inode;
 333         return 0;
 334 }
 335 
 336 int ext_mknod(struct inode * dir, const char * name, int len, int mode, int rdev)
     /*  */
 337 {
 338         struct inode * inode;
 339         struct buffer_head * bh;
 340         struct ext_dir_entry * de;
 341 
 342         if (!dir)
 343                 return -ENOENT;
 344         bh = ext_find_entry(dir,name,len,&de,NULL,NULL);
 345         if (bh) {
 346                 brelse(bh);
 347                 iput(dir);
 348                 return -EEXIST;
 349         }
 350         inode = ext_new_inode(dir);
 351         if (!inode) {
 352                 iput(dir);
 353                 return -ENOSPC;
 354         }
 355         inode->i_uid = current->fsuid;
 356         inode->i_mode = mode;
 357         inode->i_op = NULL;
 358         if (S_ISREG(inode->i_mode))
 359                 inode->i_op = &ext_file_inode_operations;
 360         else if (S_ISDIR(inode->i_mode)) {
 361                 inode->i_op = &ext_dir_inode_operations;
 362                 if (dir->i_mode & S_ISGID)
 363                         inode->i_mode |= S_ISGID;
 364         }
 365         else if (S_ISLNK(inode->i_mode))
 366                 inode->i_op = &ext_symlink_inode_operations;
 367         else if (S_ISCHR(inode->i_mode))
 368                 inode->i_op = &chrdev_inode_operations;
 369         else if (S_ISBLK(inode->i_mode))
 370                 inode->i_op = &blkdev_inode_operations;
 371         else if (S_ISFIFO(inode->i_mode))
 372                 init_fifo(inode);
 373         if (S_ISBLK(mode) || S_ISCHR(mode))
 374                 inode->i_rdev = rdev;
 375 #if 0
 376         inode->i_mtime = inode->i_atime = CURRENT_TIME;
 377 #endif
 378         inode->i_dirt = 1;
 379         bh = ext_add_entry(dir,name,len,&de);
 380         if (!bh) {
 381                 inode->i_nlink--;
 382                 inode->i_dirt = 1;
 383                 iput(inode);
 384                 iput(dir);
 385                 return -ENOSPC;
 386         }
 387         de->inode = inode->i_ino;
 388         mark_buffer_dirty(bh, 1);
 389         brelse(bh);
 390         iput(dir);
 391         iput(inode);
 392         return 0;
 393 }
 394 
 395 int ext_mkdir(struct inode * dir, const char * name, int len, int mode)
     /*  */
 396 {
 397         struct inode * inode;
 398         struct buffer_head * bh, *dir_block;
 399         struct ext_dir_entry * de;
 400         
 401         bh = ext_find_entry(dir,name,len,&de,NULL,NULL);
 402         if (bh) {
 403                 brelse(bh);
 404                 iput(dir);
 405                 return -EEXIST;
 406         }
 407         inode = ext_new_inode(dir);
 408         if (!inode) {
 409                 iput(dir);
 410                 return -ENOSPC;
 411         }
 412         inode->i_op = &ext_dir_inode_operations;
 413         inode->i_size = 2 * 16; /* Each entry is coded on 16 bytes for "." and ".."
 414                                         - 4 bytes for the inode number,
 415                                         - 2 bytes for the record length
 416                                         - 2 bytes for the name length
 417                                         - 8 bytes for the name */
 418 #if 0
 419         inode->i_mtime = inode->i_atime = CURRENT_TIME;
 420 #endif
 421         dir_block = ext_bread(inode,0,1);
 422         if (!dir_block) {
 423                 iput(dir);
 424                 inode->i_nlink--;
 425                 inode->i_dirt = 1;
 426                 iput(inode);
 427                 return -ENOSPC;
 428         }
 429         de = (struct ext_dir_entry *) dir_block->b_data;
 430         de->inode=inode->i_ino;
 431         de->rec_len=16;
 432         de->name_len=1;
 433         strcpy(de->name,".");
 434         de = (struct ext_dir_entry *) ((char *) de + de->rec_len);
 435         de->inode = dir->i_ino;
 436         de->rec_len=16;
 437         de->name_len=2;
 438         strcpy(de->name,"..");
 439         inode->i_nlink = 2;
 440         mark_buffer_dirty(dir_block, 1);
 441         brelse(dir_block);
 442         inode->i_mode = S_IFDIR | (mode & 0777 & ~current->fs->umask);
 443         if (dir->i_mode & S_ISGID)
 444                 inode->i_mode |= S_ISGID;
 445         inode->i_dirt = 1;
 446         bh = ext_add_entry(dir,name,len,&de);
 447         if (!bh) {
 448                 iput(dir);
 449                 inode->i_nlink=0;
 450                 iput(inode);
 451                 return -ENOSPC;
 452         }
 453         de->inode = inode->i_ino;
 454         mark_buffer_dirty(bh, 1);
 455         dir->i_nlink++;
 456         dir->i_dirt = 1;
 457         iput(dir);
 458         iput(inode);
 459         brelse(bh);
 460         return 0;
 461 }
 462 
 463 /*
 464  * routine to check that the specified directory is empty (for rmdir)
 465  */
 466 static int empty_dir(struct inode * inode)
     /*  */
 467 {
 468         unsigned long offset;
 469         struct buffer_head * bh;
 470         struct ext_dir_entry * de, * de1;
 471 
 472         if (inode->i_size < 2 * 12 || !(bh = ext_bread(inode,0,0))) {
 473                 printk("warning - bad directory on dev %04x\n",inode->i_dev);
 474                 return 1;
 475         }
 476         de = (struct ext_dir_entry *) bh->b_data;
 477         de1 = (struct ext_dir_entry *) ((char *) de + de->rec_len);
 478         if (de->inode != inode->i_ino || !de1->inode || 
 479             strcmp(".",de->name) || strcmp("..",de1->name)) {
 480                 printk("warning - bad directory on dev %04x\n",inode->i_dev);
 481                 return 1;
 482         }
 483         offset = de->rec_len + de1->rec_len;
 484         de = (struct ext_dir_entry *) ((char *) de1 + de1->rec_len);
 485         while (offset < inode->i_size ) {
 486                 if ((void *) de >= (void *) (bh->b_data+BLOCK_SIZE)) {
 487                         brelse(bh);
 488                         bh = ext_bread(inode, offset >> BLOCK_SIZE_BITS,1);
 489                         if (!bh) {
 490                                 offset += BLOCK_SIZE;
 491                                 continue;
 492                         }
 493                         de = (struct ext_dir_entry *) bh->b_data;
 494                 }
 495                 if (de->rec_len < 8 || de->rec_len %4 != 0 ||
 496                     de->rec_len < de->name_len + 8) {
 497                         printk ("empty_dir: bad dir entry\n");
 498                         printk ("dev=%d, dir=%ld, offset=%ld, rec_len=%d, name_len=%d\n",
 499                                 inode->i_dev, inode->i_ino, offset, de->rec_len, de->name_len);
 500                         brelse (bh);
 501                         return 1;
 502                 }
 503                 if (de->inode) {
 504                         brelse(bh);
 505                         return 0;
 506                 }
 507                 offset += de->rec_len;
 508                 de = (struct ext_dir_entry *) ((char *) de + de->rec_len);
 509         }
 510         brelse(bh);
 511         return 1;
 512 }
 513 
 514 static inline void ext_merge_entries (struct ext_dir_entry * de,
     /*  */
 515         struct ext_dir_entry * pde, struct ext_dir_entry * nde)
 516 {
 517         if (nde && !nde->inode)
 518                 de->rec_len += nde->rec_len;
 519         if (pde && !pde->inode)
 520                 pde->rec_len += de->rec_len;
 521 }
 522 
 523 int ext_rmdir(struct inode * dir, const char * name, int len)
     /*  */
 524 {
 525         int retval;
 526         struct inode * inode;
 527         struct buffer_head * bh;
 528         struct ext_dir_entry * de, * pde, * nde;
 529 
 530         inode = NULL;
 531         bh = ext_find_entry(dir,name,len,&de,&pde,&nde);
 532         retval = -ENOENT;
 533         if (!bh)
 534                 goto end_rmdir;
 535         retval = -EPERM;
 536         if (!(inode = iget(dir->i_sb, de->inode)))
 537                 goto end_rmdir;
 538         if ((dir->i_mode & S_ISVTX) && !fsuser() &&
 539             current->fsuid != inode->i_uid &&
 540             current->fsuid != dir->i_uid)
 541                 goto end_rmdir;
 542         if (inode->i_dev != dir->i_dev)
 543                 goto end_rmdir;
 544         if (inode == dir)       /* we may not delete ".", but "../dir" is ok */
 545                 goto end_rmdir;
 546         if (!S_ISDIR(inode->i_mode)) {
 547                 retval = -ENOTDIR;
 548                 goto end_rmdir;
 549         }
 550         if (!empty_dir(inode)) {
 551                 retval = -ENOTEMPTY;
 552                 goto end_rmdir;
 553         }
 554         if (inode->i_count > 1) {
 555                 retval = -EBUSY;
 556                 goto end_rmdir;
 557         }
 558         if (inode->i_nlink != 2)
 559                 printk("empty directory has nlink!=2 (%d)\n",inode->i_nlink);
 560         de->inode = 0;
 561         de->name_len = 0;
 562         ext_merge_entries (de, pde, nde);
 563         mark_buffer_dirty(bh, 1);
 564         inode->i_nlink=0;
 565         inode->i_dirt=1;
 566         dir->i_nlink--;
 567         inode->i_ctime = dir->i_ctime = dir->i_mtime = CURRENT_TIME;
 568         dir->i_dirt=1;
 569         retval = 0;
 570 end_rmdir:
 571         iput(dir);
 572         iput(inode);
 573         brelse(bh);
 574         return retval;
 575 }
 576 
 577 int ext_unlink(struct inode * dir, const char * name, int len)
     /*  */
 578 {
 579         int retval;
 580         struct inode * inode;
 581         struct buffer_head * bh;
 582         struct ext_dir_entry * de, * pde, * nde;
 583 
 584         retval = -ENOENT;
 585         inode = NULL;
 586         bh = ext_find_entry(dir,name,len,&de,&pde,&nde);
 587         if (!bh)
 588                 goto end_unlink;
 589         if (!(inode = iget(dir->i_sb, de->inode)))
 590                 goto end_unlink;
 591         retval = -EPERM;
 592         if ((dir->i_mode & S_ISVTX) && !fsuser() &&
 593             current->fsuid != inode->i_uid &&
 594             current->fsuid != dir->i_uid)
 595                 goto end_unlink;
 596         if (S_ISDIR(inode->i_mode))
 597                 goto end_unlink;
 598         if (!inode->i_nlink) {
 599                 printk("Deleting nonexistent file (%04x:%ld), %d\n",
 600                         inode->i_dev,inode->i_ino,inode->i_nlink);
 601                 inode->i_nlink=1;
 602         }
 603         de->inode = 0;
 604         de->name_len = 0;
 605         ext_merge_entries (de, pde, nde);
 606         mark_buffer_dirty(bh, 1);
 607         inode->i_nlink--;
 608         inode->i_dirt = 1;
 609         inode->i_ctime = CURRENT_TIME;
 610         dir->i_ctime = dir->i_mtime = inode->i_ctime;
 611         dir->i_dirt = 1;
 612         retval = 0;
 613 end_unlink:
 614         brelse(bh);
 615         iput(inode);
 616         iput(dir);
 617         return retval;
 618 }
 619 
 620 int ext_symlink(struct inode * dir, const char * name, int len, const char * symname)
     /*  */
 621 {
 622         struct ext_dir_entry * de;
 623         struct inode * inode = NULL;
 624         struct buffer_head * bh = NULL, * name_block = NULL;
 625         int i;
 626         char c;
 627 
 628         if (!(inode = ext_new_inode(dir))) {
 629                 iput(dir);
 630                 return -ENOSPC;
 631         }
 632         inode->i_mode = S_IFLNK | 0777;
 633         inode->i_op = &ext_symlink_inode_operations;
 634         name_block = ext_bread(inode,0,1);
 635         if (!name_block) {
 636                 iput(dir);
 637                 inode->i_nlink--;
 638                 inode->i_dirt = 1;
 639                 iput(inode);
 640                 return -ENOSPC;
 641         }
 642         i = 0;
 643         while (i < 1023 && (c = *(symname++)))
 644                 name_block->b_data[i++] = c;
 645         name_block->b_data[i] = 0;
 646         mark_buffer_dirty(name_block, 1);
 647         brelse(name_block);
 648         inode->i_size = i;
 649         inode->i_dirt = 1;
 650         bh = ext_find_entry(dir,name,len,&de,NULL,NULL);
 651         if (bh) {
 652                 inode->i_nlink--;
 653                 inode->i_dirt = 1;
 654                 iput(inode);
 655                 brelse(bh);
 656                 iput(dir);
 657                 return -EEXIST;
 658         }
 659         bh = ext_add_entry(dir,name,len,&de);
 660         if (!bh) {
 661                 inode->i_nlink--;
 662                 inode->i_dirt = 1;
 663                 iput(inode);
 664                 iput(dir);
 665                 return -ENOSPC;
 666         }
 667         de->inode = inode->i_ino;
 668         mark_buffer_dirty(bh, 1);
 669         brelse(bh);
 670         iput(dir);
 671         iput(inode);
 672         return 0;
 673 }
 674 
 675 int ext_link(struct inode * oldinode, struct inode * dir, const char * name, int len)
     /*  */
 676 {
 677         struct ext_dir_entry * de;
 678         struct buffer_head * bh;
 679 
 680         if (S_ISDIR(oldinode->i_mode)) {
 681                 iput(oldinode);
 682                 iput(dir);
 683                 return -EPERM;
 684         }
 685         if (oldinode->i_nlink > 32000) {
 686                 iput(oldinode);
 687                 iput(dir);
 688                 return -EMLINK;
 689         }
 690         bh = ext_find_entry(dir,name,len,&de,NULL,NULL);
 691         if (bh) {
 692                 brelse(bh);
 693                 iput(dir);
 694                 iput(oldinode);
 695                 return -EEXIST;
 696         }
 697         bh = ext_add_entry(dir,name,len,&de);
 698         if (!bh) {
 699                 iput(dir);
 700                 iput(oldinode);
 701                 return -ENOSPC;
 702         }
 703         de->inode = oldinode->i_ino;
 704         mark_buffer_dirty(bh, 1);
 705         brelse(bh);
 706         iput(dir);
 707         oldinode->i_nlink++;
 708         oldinode->i_ctime = CURRENT_TIME;
 709         oldinode->i_dirt = 1;
 710         iput(oldinode);
 711         return 0;
 712 }
 713 
 714 static int subdir(struct inode * new_inode, struct inode * old_inode)
     /*  */
 715 {
 716         int ino;
 717         int result;
 718 
 719         new_inode->i_count++;
 720         result = 0;
 721         for (;;) {
 722                 if (new_inode == old_inode) {
 723                         result = 1;
 724                         break;
 725                 }
 726                 if (new_inode->i_dev != old_inode->i_dev)
 727                         break;
 728                 ino = new_inode->i_ino;
 729                 if (ext_lookup(new_inode,"..",2,&new_inode))
 730                         break;
 731                 if (new_inode->i_ino == ino)
 732                         break;
 733         }
 734         iput(new_inode);
 735         return result;
 736 }
 737 
 738 #define PARENT_INO(buffer) \
 739 ((struct ext_dir_entry *) ((char *) buffer + \
 740 ((struct ext_dir_entry *) buffer)->rec_len))->inode
 741 
 742 #define PARENT_NAME(buffer) \
 743 ((struct ext_dir_entry *) ((char *) buffer + \
 744 ((struct ext_dir_entry *) buffer)->rec_len))->name
 745 
 746 /*
 747  * rename uses retrying to avoid race-conditions: at least they should be minimal.
 748  * it tries to allocate all the blocks, then sanity-checks, and if the sanity-
 749  * checks fail, it tries to restart itself again. Very practical - no changes
 750  * are done until we know everything works ok.. and then all the changes can be
 751  * done in one fell swoop when we have claimed all the buffers needed.
 752  *
 753  * Anybody can rename anything with this: the permission checks are left to the
 754  * higher-level routines.
 755  */
 756 static int do_ext_rename(struct inode * old_dir, const char * old_name, int old_len,
     /*  */
 757         struct inode * new_dir, const char * new_name, int new_len)
 758 {
 759         struct inode * old_inode, * new_inode;
 760         struct buffer_head * old_bh, * new_bh, * dir_bh;
 761         struct ext_dir_entry * old_de, * new_de, * pde, * nde;
 762         int retval;
 763 
 764         goto start_up;
 765 try_again:
 766         brelse(old_bh);
 767         brelse(new_bh);
 768         brelse(dir_bh);
 769         iput(old_inode);
 770         iput(new_inode);
 771         current->counter = 0;
 772         schedule();
 773 start_up:
 774         old_inode = new_inode = NULL;
 775         old_bh = new_bh = dir_bh = NULL;
 776         old_bh = ext_find_entry(old_dir,old_name,old_len,&old_de,&pde,&nde);
 777         retval = -ENOENT;
 778         if (!old_bh)
 779                 goto end_rename;
 780         old_inode = __iget(old_dir->i_sb, old_de->inode,0); /* don't cross mnt-points */
 781         if (!old_inode)
 782                 goto end_rename;
 783         retval = -EPERM;
 784         if ((old_dir->i_mode & S_ISVTX) && 
 785             current->fsuid != old_inode->i_uid &&
 786             current->fsuid != old_dir->i_uid && !fsuser())
 787                 goto end_rename;
 788         new_bh = ext_find_entry(new_dir,new_name,new_len,&new_de,NULL,NULL);
 789         if (new_bh) {
 790                 new_inode = __iget(new_dir->i_sb, new_de->inode,0); /* don't cross mnt-points */
 791                 if (!new_inode) {
 792                         brelse(new_bh);
 793                         new_bh = NULL;
 794                 }
 795         }
 796         if (new_inode == old_inode) {
 797                 retval = 0;
 798                 goto end_rename;
 799         }
 800         if (new_inode && S_ISDIR(new_inode->i_mode)) {
 801                 retval = -EEXIST;
 802                 goto end_rename;
 803         }
 804         retval = -EPERM;
 805         if (new_inode && (new_dir->i_mode & S_ISVTX) && 
 806             current->fsuid != new_inode->i_uid &&
 807             current->fsuid != new_dir->i_uid && !fsuser())
 808                 goto end_rename;
 809         if (S_ISDIR(old_inode->i_mode)) {
 810                 retval = -EEXIST;
 811                 if (new_bh)
 812                         goto end_rename;
 813                 retval = -EACCES;
 814                 if (!permission(old_inode, MAY_WRITE))
 815                         goto end_rename;
 816                 retval = -EINVAL;
 817                 if (subdir(new_dir, old_inode))
 818                         goto end_rename;
 819                 retval = -EIO;
 820                 dir_bh = ext_bread(old_inode,0,0);
 821                 if (!dir_bh)
 822                         goto end_rename;
 823                 if (PARENT_INO(dir_bh->b_data) != old_dir->i_ino)
 824                         goto end_rename;
 825         }
 826         if (!new_bh)
 827                 new_bh = ext_add_entry(new_dir,new_name,new_len,&new_de);
 828         retval = -ENOSPC;
 829         if (!new_bh)
 830                 goto end_rename;
 831 /* sanity checking before doing the rename - avoid races */
 832         if (new_inode && (new_de->inode != new_inode->i_ino))
 833                 goto try_again;
 834         if (new_de->inode && !new_inode)
 835                 goto try_again;
 836         if (old_de->inode != old_inode->i_ino)
 837                 goto try_again;
 838 /* ok, that's it */
 839         old_de->inode = 0;
 840         old_de->name_len = 0;
 841         new_de->inode = old_inode->i_ino;
 842         ext_merge_entries (old_de, pde, nde);
 843         if (new_inode) {
 844                 new_inode->i_nlink--;
 845                 new_inode->i_dirt = 1;
 846         }
 847         mark_buffer_dirty(old_bh, 1);
 848         mark_buffer_dirty(new_bh, 1);
 849         if (dir_bh) {
 850                 PARENT_INO(dir_bh->b_data) = new_dir->i_ino;
 851                 mark_buffer_dirty(dir_bh, 1);
 852                 old_dir->i_nlink--;
 853                 new_dir->i_nlink++;
 854                 old_dir->i_dirt = 1;
 855                 new_dir->i_dirt = 1;
 856         }
 857         retval = 0;
 858 end_rename:
 859         brelse(dir_bh);
 860         brelse(old_bh);
 861         brelse(new_bh);
 862         iput(old_inode);
 863         iput(new_inode);
 864         iput(old_dir);
 865         iput(new_dir);
 866         return retval;
 867 }
 868 
 869 /*
 870  * Ok, rename also locks out other renames, as they can change the parent of
 871  * a directory, and we don't want any races. Other races are checked for by
 872  * "do_rename()", which restarts if there are inconsistencies.
 873  *
 874  * Note that there is no race between different filesystems: it's only within
 875  * the same device that races occur: many renames can happen at once, as long
 876  * as they are on different partitions.
 877  */
 878 int ext_rename(struct inode * old_dir, const char * old_name, int old_len,
     /*  */
 879         struct inode * new_dir, const char * new_name, int new_len)
 880 {
 881         static struct wait_queue * wait = NULL;
 882         static int lock = 0;
 883         int result;
 884 
 885         while (lock)
 886                 sleep_on(&wait);
 887         lock = 1;
 888         result = do_ext_rename(old_dir, old_name, old_len,
 889                 new_dir, new_name, new_len);
 890         lock = 0;
 891         wake_up(&wait);
 892         return result;
 893 }
/* */
root/fs/ext/namei.c

DEFINITIONS
