fs/namei.c

/* */
This source file includes following definitions.
get_max_filename
getname
putname
permission
get_write_access
put_write_access
lookup
follow_link
dir_namei
_namei
lnamei
namei
open_namei
do_mknod
sys_mknod
do_mkdir
sys_mkdir
do_rmdir
sys_rmdir
do_unlink
sys_unlink
do_symlink
sys_symlink
do_link
sys_link
do_rename
sys_rename
   1 /*
   2  *  linux/fs/namei.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6 
   7 /*
   8  * Some corrections by tytso.
   9  */
  10 
  11 #include <asm/segment.h>
  12 
  13 #include <linux/errno.h>
  14 #include <linux/sched.h>
  15 #include <linux/kernel.h>
  16 #include <linux/string.h>
  17 #include <linux/fcntl.h>
  18 #include <linux/stat.h>
  19 #include <linux/mm.h>
  20 
  21 #define ACC_MODE(x) ("\000\004\002\006"[(x)&O_ACCMODE])
  22 
  23 /*
  24  * How long a filename can we get from user space?
  25  *  -EFAULT if invalid area
  26  *  0 if ok (ENAMETOOLONG before EFAULT)
  27  *  >0 EFAULT after xx bytes
  28  */
  29 static inline int get_max_filename(unsigned long address)
     /*  */
  30 {
  31         struct vm_area_struct * vma;
  32 
  33         if (get_fs() == KERNEL_DS)
  34                 return 0;
  35         vma = find_vma(current, address);
  36         if (!vma || vma->vm_start > address || !(vma->vm_flags & VM_READ))
  37                 return -EFAULT;
  38         address = vma->vm_end - address;
  39         if (address > PAGE_SIZE)
  40                 return 0;
  41         if (vma->vm_next && vma->vm_next->vm_start == vma->vm_end &&
  42            (vma->vm_next->vm_flags & VM_READ))
  43                 return 0;
  44         return address;
  45 }
  46 
  47 /*
  48  * In order to reduce some races, while at the same time doing additional
  49  * checking and hopefully speeding things up, we copy filenames to the
  50  * kernel data space before using them..
  51  *
  52  * POSIX.1 2.4: an empty pathname is invalid (ENOENT).
  53  */
  54 int getname(const char * filename, char **result)
     /*  */
  55 {
  56         int i, error;
  57         unsigned long page;
  58         char * tmp, c;
  59 
  60         i = get_max_filename((unsigned long) filename);
  61         if (i < 0)
  62                 return i;
  63         error = -EFAULT;
  64         if (!i) {
  65                 error = -ENAMETOOLONG;
  66                 i = PAGE_SIZE;
  67         }
  68         c = get_user(filename++);
  69         if (!c)
  70                 return -ENOENT;
  71         if(!(page = __get_free_page(GFP_KERNEL)))
  72                 return -ENOMEM;
  73         *result = tmp = (char *) page;
  74         while (--i) {
  75                 *(tmp++) = c;
  76                 c = get_user(filename++);
  77                 if (!c) {
  78                         *tmp = '\0';
  79                         return 0;
  80                 }
  81         }
  82         free_page(page);
  83         return error;
  84 }
  85 
  86 void putname(char * name)
     /*  */
  87 {
  88         free_page((unsigned long) name);
  89 }
  90 
  91 /*
  92  *      permission()
  93  *
  94  * is used to check for read/write/execute permissions on a file.
  95  * We use "fsuid" for this, letting us set arbitrary permissions
  96  * for filesystem access without changing the "normal" uids which
  97  * are used for other things..
  98  */
  99 int permission(struct inode * inode,int mask)
     /*  */
 100 {
 101         int mode = inode->i_mode;
 102 
 103         if (inode->i_op && inode->i_op->permission)
 104                 return inode->i_op->permission(inode, mask);
 105         else if ((mask & S_IWOTH) && IS_IMMUTABLE(inode))
 106                 return -EACCES; /* Nobody gets write access to an immutable file */
 107         else if (current->fsuid == inode->i_uid)
 108                 mode >>= 6;
 109         else if (in_group_p(inode->i_gid))
 110                 mode >>= 3;
 111         if (((mode & mask & 0007) == mask) || fsuser())
 112                 return 0;
 113         return -EACCES;
 114 }
 115 
 116 /*
 117  * get_write_access() gets write permission for a file.
 118  * put_write_access() releases this write permission.
 119  * This is used for regular files.
 120  * We cannot support write (and maybe mmap read-write shared) accesses and
 121  * MAP_DENYWRITE mmappings simultaneously.
 122  */
 123 int get_write_access(struct inode * inode)
     /*  */
 124 {
 125         struct task_struct * p;
 126 
 127         if ((inode->i_count > 1) && S_ISREG(inode->i_mode)) /* shortcut */
 128                 for_each_task(p) {
 129                         struct vm_area_struct * mpnt;
 130                         if (!p->mm)
 131                                 continue;
 132                         for(mpnt = p->mm->mmap; mpnt; mpnt = mpnt->vm_next) {
 133                                 if (inode != mpnt->vm_inode)
 134                                         continue;
 135                                 if (mpnt->vm_flags & VM_DENYWRITE)
 136                                         return -ETXTBSY;
 137                         }
 138                 }
 139         inode->i_writecount++;
 140         return 0;
 141 }
 142 
 143 void put_write_access(struct inode * inode)
     /*  */
 144 {
 145         inode->i_writecount--;
 146 }
 147 
 148 /*
 149  * lookup() looks up one part of a pathname, using the fs-dependent
 150  * routines (currently minix_lookup) for it. It also checks for
 151  * fathers (pseudo-roots, mount-points)
 152  */
 153 int lookup(struct inode * dir,const char * name, int len,
     /*  */
 154            struct inode ** result)
 155 {
 156         struct super_block * sb;
 157         int perm;
 158 
 159         *result = NULL;
 160         if (!dir)
 161                 return -ENOENT;
 162 /* check permissions before traversing mount-points */
 163         perm = permission(dir,MAY_EXEC);
 164         if (len==2 && name[0] == '.' && name[1] == '.') {
 165                 if (dir == current->fs->root) {
 166                         *result = dir;
 167                         return 0;
 168                 } else if ((sb = dir->i_sb) && (dir == sb->s_mounted)) {
 169                         iput(dir);
 170                         dir = sb->s_covered;
 171                         if (!dir)
 172                                 return -ENOENT;
 173                         dir->i_count++;
 174                 }
 175         }
 176         if (!dir->i_op || !dir->i_op->lookup) {
 177                 iput(dir);
 178                 return -ENOTDIR;
 179         }
 180         if (perm != 0) {
 181                 iput(dir);
 182                 return perm;
 183         }
 184         if (!len) {
 185                 *result = dir;
 186                 return 0;
 187         }
 188         return dir->i_op->lookup(dir, name, len, result);
 189 }
 190 
 191 int follow_link(struct inode * dir, struct inode * inode,
     /*  */
 192         int flag, int mode, struct inode ** res_inode)
 193 {
 194         if (!dir || !inode) {
 195                 iput(dir);
 196                 iput(inode);
 197                 *res_inode = NULL;
 198                 return -ENOENT;
 199         }
 200         if (!inode->i_op || !inode->i_op->follow_link) {
 201                 iput(dir);
 202                 *res_inode = inode;
 203                 return 0;
 204         }
 205         return inode->i_op->follow_link(dir,inode,flag,mode,res_inode);
 206 }
 207 
 208 /*
 209  *      dir_namei()
 210  *
 211  * dir_namei() returns the inode of the directory of the
 212  * specified name, and the name within that directory.
 213  */
 214 static int dir_namei(const char *pathname, int *namelen, const char **name,
     /*  */
 215                      struct inode * base, struct inode **res_inode)
 216 {
 217         char c;
 218         const char * thisname;
 219         int len,error;
 220         struct inode * inode;
 221 
 222         *res_inode = NULL;
 223         if (!base) {
 224                 base = current->fs->pwd;
 225                 base->i_count++;
 226         }
 227         if ((c = *pathname) == '/') {
 228                 iput(base);
 229                 base = current->fs->root;
 230                 pathname++;
 231                 base->i_count++;
 232         }
 233         while (1) {
 234                 thisname = pathname;
 235                 for(len=0;(c = *(pathname++))&&(c != '/');len++)
 236                         /* nothing */ ;
 237                 if (!c)
 238                         break;
 239                 base->i_count++;
 240                 error = lookup(base, thisname, len, &inode);
 241                 if (error) {
 242                         iput(base);
 243                         return error;
 244                 }
 245                 error = follow_link(base,inode,0,0,&base);
 246                 if (error)
 247                         return error;
 248         }
 249         if (!base->i_op || !base->i_op->lookup) {
 250                 iput(base);
 251                 return -ENOTDIR;
 252         }
 253         *name = thisname;
 254         *namelen = len;
 255         *res_inode = base;
 256         return 0;
 257 }
 258 
 259 static int _namei(const char * pathname, struct inode * base,
     /*  */
 260                   int follow_links, struct inode ** res_inode)
 261 {
 262         const char *basename;
 263         int namelen,error;
 264         struct inode * inode;
 265 
 266         *res_inode = NULL;
 267         error = dir_namei(pathname, &namelen, &basename, base, &base);
 268         if (error)
 269                 return error;
 270         base->i_count++;        /* lookup uses up base */
 271         error = lookup(base, basename, namelen, &inode);
 272         if (error) {
 273                 iput(base);
 274                 return error;
 275         }
 276         if (follow_links) {
 277                 error = follow_link(base, inode, 0, 0, &inode);
 278                 if (error)
 279                         return error;
 280         } else
 281                 iput(base);
 282         *res_inode = inode;
 283         return 0;
 284 }
 285 
 286 int lnamei(const char *pathname, struct inode **res_inode)
     /*  */
 287 {
 288         int error;
 289         char * tmp;
 290 
 291         error = getname(pathname, &tmp);
 292         if (!error) {
 293                 error = _namei(tmp, NULL, 0, res_inode);
 294                 putname(tmp);
 295         }
 296         return error;
 297 }
 298 
 299 /*
 300  *      namei()
 301  *
 302  * is used by most simple commands to get the inode of a specified name.
 303  * Open, link etc use their own routines, but this is enough for things
 304  * like 'chmod' etc.
 305  */
 306 int namei(const char *pathname, struct inode **res_inode)
     /*  */
 307 {
 308         int error;
 309         char * tmp;
 310 
 311         error = getname(pathname, &tmp);
 312         if (!error) {
 313                 error = _namei(tmp, NULL, 1, res_inode);
 314                 putname(tmp);
 315         }
 316         return error;
 317 }
 318 
 319 /*
 320  *      open_namei()
 321  *
 322  * namei for open - this is in fact almost the whole open-routine.
 323  *
 324  * Note that the low bits of "flag" aren't the same as in the open
 325  * system call - they are 00 - no permissions needed
 326  *                        01 - read permission needed
 327  *                        10 - write permission needed
 328  *                        11 - read/write permissions needed
 329  * which is a lot more logical, and also allows the "no perm" needed
 330  * for symlinks (where the permissions are checked later).
 331  */
 332 int open_namei(const char * pathname, int flag, int mode,
     /*  */
 333                struct inode ** res_inode, struct inode * base)
 334 {
 335         const char * basename;
 336         int namelen,error;
 337         struct inode * dir, *inode;
 338 
 339         mode &= S_IALLUGO & ~current->fs->umask;
 340         mode |= S_IFREG;
 341         error = dir_namei(pathname, &namelen, &basename, base, &dir);
 342         if (error)
 343                 return error;
 344         if (!namelen) {                 /* special case: '/usr/' etc */
 345                 if (flag & 2) {
 346                         iput(dir);
 347                         return -EISDIR;
 348                 }
 349                 /* thanks to Paul Pluzhnikov for noticing this was missing.. */
 350                 if ((error = permission(dir,ACC_MODE(flag))) != 0) {
 351                         iput(dir);
 352                         return error;
 353                 }
 354                 *res_inode=dir;
 355                 return 0;
 356         }
 357         dir->i_count++;         /* lookup eats the dir */
 358         if (flag & O_CREAT) {
 359                 down(&dir->i_sem);
 360                 error = lookup(dir, basename, namelen, &inode);
 361                 if (!error) {
 362                         if (flag & O_EXCL) {
 363                                 iput(inode);
 364                                 error = -EEXIST;
 365                         }
 366                 } else if ((error = permission(dir,MAY_WRITE | MAY_EXEC)) != 0)
 367                         ;       /* error is already set! */
 368                 else if (!dir->i_op || !dir->i_op->create)
 369                         error = -EACCES;
 370                 else if (IS_RDONLY(dir))
 371                         error = -EROFS;
 372                 else {
 373                         dir->i_count++;         /* create eats the dir */
 374                         if (dir->i_sb && dir->i_sb->dq_op)
 375                                 dir->i_sb->dq_op->initialize(dir, -1);
 376                         error = dir->i_op->create(dir, basename, namelen, mode, res_inode);
 377                         up(&dir->i_sem);
 378                         iput(dir);
 379                         return error;
 380                 }
 381                 up(&dir->i_sem);
 382         } else
 383                 error = lookup(dir, basename, namelen, &inode);
 384         if (error) {
 385                 iput(dir);
 386                 return error;
 387         }
 388         error = follow_link(dir,inode,flag,mode,&inode);
 389         if (error)
 390                 return error;
 391         if (S_ISDIR(inode->i_mode) && (flag & 2)) {
 392                 iput(inode);
 393                 return -EISDIR;
 394         }
 395         if ((error = permission(inode,ACC_MODE(flag))) != 0) {
 396                 iput(inode);
 397                 return error;
 398         }
 399         if (S_ISFIFO(inode->i_mode) || S_ISSOCK(inode->i_mode)) {
 400                 /*
 401                  * 2-Feb-1995 Bruce Perens <Bruce@Pixar.com>
 402                  * Allow opens of Unix domain sockets and FIFOs for write on
 403                  * read-only filesystems. Their data does not live on the disk.
 404                  *
 405                  * If there was something like IS_NODEV(inode) for
 406                  * pipes and/or sockets I'd check it here.
 407                  */
 408         }
 409         else if (S_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) {
 410                 if (IS_NODEV(inode)) {
 411                         iput(inode);
 412                         return -EACCES;
 413                 }
 414                 flag &= ~O_TRUNC;
 415         } else {
 416                 if (IS_RDONLY(inode) && (flag & 2)) {
 417                         iput(inode);
 418                         return -EROFS;
 419                 }
 420         }
 421         /*
 422          * An append-only file must be opened in append mode for writing
 423          */
 424         if (IS_APPEND(inode) && ((flag & FMODE_WRITE) && !(flag & O_APPEND))) {
 425                 iput(inode);
 426                 return -EPERM;
 427         }
 428         if (flag & O_TRUNC) {
 429                 if ((error = get_write_access(inode))) {
 430                         iput(inode);
 431                         return error;
 432                 }
 433                 if (inode->i_sb && inode->i_sb->dq_op)
 434                         inode->i_sb->dq_op->initialize(inode, -1);
 435                         
 436                 error = do_truncate(inode, 0);
 437                 put_write_access(inode);
 438                 if (error) {
 439                         iput(inode);
 440                         return error;
 441                 }
 442         } else
 443                 if (flag & FMODE_WRITE)
 444                         if (inode->i_sb && inode->i_sb->dq_op)
 445                                 inode->i_sb->dq_op->initialize(inode, -1);
 446         *res_inode = inode;
 447         return 0;
 448 }
 449 
 450 int do_mknod(const char * filename, int mode, dev_t dev)
     /*  */
 451 {
 452         const char * basename;
 453         int namelen, error;
 454         struct inode * dir;
 455 
 456         mode &= ~current->fs->umask;
 457         error = dir_namei(filename, &namelen, &basename, NULL, &dir);
 458         if (error)
 459                 return error;
 460         if (!namelen) {
 461                 iput(dir);
 462                 return -ENOENT;
 463         }
 464         if (IS_RDONLY(dir)) {
 465                 iput(dir);
 466                 return -EROFS;
 467         }
 468         if ((error = permission(dir,MAY_WRITE | MAY_EXEC)) != 0) {
 469                 iput(dir);
 470                 return error;
 471         }
 472         if (!dir->i_op || !dir->i_op->mknod) {
 473                 iput(dir);
 474                 return -EPERM;
 475         }
 476         dir->i_count++;
 477         if (dir->i_sb && dir->i_sb->dq_op)
 478                 dir->i_sb->dq_op->initialize(dir, -1);
 479         down(&dir->i_sem);
 480         error = dir->i_op->mknod(dir,basename,namelen,mode,dev);
 481         up(&dir->i_sem);
 482         iput(dir);
 483         return error;
 484 }
 485 
 486 asmlinkage int sys_mknod(const char * filename, int mode, dev_t dev)
     /*  */
 487 {
 488         int error;
 489         char * tmp;
 490 
 491         if (S_ISDIR(mode) || (!S_ISFIFO(mode) && !fsuser()))
 492                 return -EPERM;
 493         switch (mode & S_IFMT) {
 494         case 0:
 495                 mode |= S_IFREG;
 496                 break;
 497         case S_IFREG: case S_IFCHR: case S_IFBLK: case S_IFIFO: case S_IFSOCK:
 498                 break;
 499         default:
 500                 return -EINVAL;
 501         }
 502         error = getname(filename,&tmp);
 503         if (!error) {
 504                 error = do_mknod(tmp,mode,dev);
 505                 putname(tmp);
 506         }
 507         return error;
 508 }
 509 
 510 static int do_mkdir(const char * pathname, int mode)
     /*  */
 511 {
 512         const char * basename;
 513         int namelen, error;
 514         struct inode * dir;
 515 
 516         error = dir_namei(pathname, &namelen, &basename, NULL, &dir);
 517         if (error)
 518                 return error;
 519         if (!namelen) {
 520                 iput(dir);
 521                 return -ENOENT;
 522         }
 523         if (IS_RDONLY(dir)) {
 524                 iput(dir);
 525                 return -EROFS;
 526         }
 527         if ((error = permission(dir,MAY_WRITE | MAY_EXEC)) != 0) {
 528                 iput(dir);
 529                 return error;
 530         }
 531         if (!dir->i_op || !dir->i_op->mkdir) {
 532                 iput(dir);
 533                 return -EPERM;
 534         }
 535         dir->i_count++;
 536         if (dir->i_sb && dir->i_sb->dq_op)
 537                 dir->i_sb->dq_op->initialize(dir, -1);
 538         down(&dir->i_sem);
 539         error = dir->i_op->mkdir(dir, basename, namelen, mode & 0777 & ~current->fs->umask);
 540         up(&dir->i_sem);
 541         iput(dir);
 542         return error;
 543 }
 544 
 545 asmlinkage int sys_mkdir(const char * pathname, int mode)
     /*  */
 546 {
 547         int error;
 548         char * tmp;
 549 
 550         error = getname(pathname,&tmp);
 551         if (!error) {
 552                 error = do_mkdir(tmp,mode);
 553                 putname(tmp);
 554         }
 555         return error;
 556 }
 557 
 558 static int do_rmdir(const char * name)
     /*  */
 559 {
 560         const char * basename;
 561         int namelen, error;
 562         struct inode * dir;
 563 
 564         error = dir_namei(name, &namelen, &basename, NULL, &dir);
 565         if (error)
 566                 return error;
 567         if (!namelen) {
 568                 iput(dir);
 569                 return -ENOENT;
 570         }
 571         if (IS_RDONLY(dir)) {
 572                 iput(dir);
 573                 return -EROFS;
 574         }
 575         if ((error = permission(dir,MAY_WRITE | MAY_EXEC)) != 0) {
 576                 iput(dir);
 577                 return error;
 578         }
 579         /*
 580          * A subdirectory cannot be removed from an append-only directory
 581          */
 582         if (IS_APPEND(dir)) {
 583                 iput(dir);
 584                 return -EPERM;
 585         }
 586         if (!dir->i_op || !dir->i_op->rmdir) {
 587                 iput(dir);
 588                 return -EPERM;
 589         }
 590         if (dir->i_sb && dir->i_sb->dq_op)
 591                 dir->i_sb->dq_op->initialize(dir, -1);
 592         return dir->i_op->rmdir(dir,basename,namelen);
 593 }
 594 
 595 asmlinkage int sys_rmdir(const char * pathname)
     /*  */
 596 {
 597         int error;
 598         char * tmp;
 599 
 600         error = getname(pathname,&tmp);
 601         if (!error) {
 602                 error = do_rmdir(tmp);
 603                 putname(tmp);
 604         }
 605         return error;
 606 }
 607 
 608 static int do_unlink(const char * name)
     /*  */
 609 {
 610         const char * basename;
 611         int namelen, error;
 612         struct inode * dir;
 613 
 614         error = dir_namei(name, &namelen, &basename, NULL, &dir);
 615         if (error)
 616                 return error;
 617         if (!namelen) {
 618                 iput(dir);
 619                 return -EPERM;
 620         }
 621         if (IS_RDONLY(dir)) {
 622                 iput(dir);
 623                 return -EROFS;
 624         }
 625         if ((error = permission(dir,MAY_WRITE | MAY_EXEC)) != 0) {
 626                 iput(dir);
 627                 return error;
 628         }
 629         /*
 630          * A file cannot be removed from an append-only directory
 631          */
 632         if (IS_APPEND(dir)) {
 633                 iput(dir);
 634                 return -EPERM;
 635         }
 636         if (!dir->i_op || !dir->i_op->unlink) {
 637                 iput(dir);
 638                 return -EPERM;
 639         }
 640         if (dir->i_sb && dir->i_sb->dq_op)
 641                 dir->i_sb->dq_op->initialize(dir, -1);
 642         return dir->i_op->unlink(dir,basename,namelen);
 643 }
 644 
 645 asmlinkage int sys_unlink(const char * pathname)
     /*  */
 646 {
 647         int error;
 648         char * tmp;
 649 
 650         error = getname(pathname,&tmp);
 651         if (!error) {
 652                 error = do_unlink(tmp);
 653                 putname(tmp);
 654         }
 655         return error;
 656 }
 657 
 658 static int do_symlink(const char * oldname, const char * newname)
     /*  */
 659 {
 660         struct inode * dir;
 661         const char * basename;
 662         int namelen, error;
 663 
 664         error = dir_namei(newname, &namelen, &basename, NULL, &dir);
 665         if (error)
 666                 return error;
 667         if (!namelen) {
 668                 iput(dir);
 669                 return -ENOENT;
 670         }
 671         if (IS_RDONLY(dir)) {
 672                 iput(dir);
 673                 return -EROFS;
 674         }
 675         if ((error = permission(dir,MAY_WRITE | MAY_EXEC)) != 0) {
 676                 iput(dir);
 677                 return error;
 678         }
 679         if (!dir->i_op || !dir->i_op->symlink) {
 680                 iput(dir);
 681                 return -EPERM;
 682         }
 683         dir->i_count++;
 684         if (dir->i_sb && dir->i_sb->dq_op)
 685                 dir->i_sb->dq_op->initialize(dir, -1);
 686         down(&dir->i_sem);
 687         error = dir->i_op->symlink(dir,basename,namelen,oldname);
 688         up(&dir->i_sem);
 689         iput(dir);
 690         return error;
 691 }
 692 
 693 asmlinkage int sys_symlink(const char * oldname, const char * newname)
     /*  */
 694 {
 695         int error;
 696         char * from, * to;
 697 
 698         error = getname(oldname,&from);
 699         if (!error) {
 700                 error = getname(newname,&to);
 701                 if (!error) {
 702                         error = do_symlink(from,to);
 703                         putname(to);
 704                 }
 705                 putname(from);
 706         }
 707         return error;
 708 }
 709 
 710 static int do_link(struct inode * oldinode, const char * newname)
     /*  */
 711 {
 712         struct inode * dir;
 713         const char * basename;
 714         int namelen, error;
 715 
 716         error = dir_namei(newname, &namelen, &basename, NULL, &dir);
 717         if (error) {
 718                 iput(oldinode);
 719                 return error;
 720         }
 721         if (!namelen) {
 722                 iput(oldinode);
 723                 iput(dir);
 724                 return -EPERM;
 725         }
 726         if (IS_RDONLY(dir)) {
 727                 iput(oldinode);
 728                 iput(dir);
 729                 return -EROFS;
 730         }
 731         if (dir->i_dev != oldinode->i_dev) {
 732                 iput(dir);
 733                 iput(oldinode);
 734                 return -EXDEV;
 735         }
 736         if ((error = permission(dir,MAY_WRITE | MAY_EXEC)) != 0) {
 737                 iput(dir);
 738                 iput(oldinode);
 739                 return error;
 740         }
 741         /*
 742          * A link to an append-only or immutable file cannot be created
 743          */
 744         if (IS_APPEND(oldinode) || IS_IMMUTABLE(oldinode)) {
 745                 iput(dir);
 746                 iput(oldinode);
 747                 return -EPERM;
 748         }
 749         if (!dir->i_op || !dir->i_op->link) {
 750                 iput(dir);
 751                 iput(oldinode);
 752                 return -EPERM;
 753         }
 754         dir->i_count++;
 755         if (dir->i_sb && dir->i_sb->dq_op)
 756                 dir->i_sb->dq_op->initialize(dir, -1);
 757         down(&dir->i_sem);
 758         error = dir->i_op->link(oldinode, dir, basename, namelen);
 759         up(&dir->i_sem);
 760         iput(dir);
 761         return error;
 762 }
 763 
 764 asmlinkage int sys_link(const char * oldname, const char * newname)
     /*  */
 765 {
 766         int error;
 767         char * to;
 768         struct inode * oldinode;
 769 
 770         error = lnamei(oldname, &oldinode);
 771         if (error)
 772                 return error;
 773         error = getname(newname,&to);
 774         if (error) {
 775                 iput(oldinode);
 776                 return error;
 777         }
 778         error = do_link(oldinode,to);
 779         putname(to);
 780         return error;
 781 }
 782 
 783 static int do_rename(const char * oldname, const char * newname)
     /*  */
 784 {
 785         struct inode * old_dir, * new_dir;
 786         const char * old_base, * new_base;
 787         int old_len, new_len, error;
 788 
 789         error = dir_namei(oldname, &old_len, &old_base, NULL, &old_dir);
 790         if (error)
 791                 return error;
 792         if ((error = permission(old_dir,MAY_WRITE | MAY_EXEC)) != 0) {
 793                 iput(old_dir);
 794                 return error;
 795         }
 796         if (!old_len || (old_base[0] == '.' &&
 797             (old_len == 1 || (old_base[1] == '.' &&
 798              old_len == 2)))) {
 799                 iput(old_dir);
 800                 return -EPERM;
 801         }
 802         error = dir_namei(newname, &new_len, &new_base, NULL, &new_dir);
 803         if (error) {
 804                 iput(old_dir);
 805                 return error;
 806         }
 807         if ((error = permission(new_dir,MAY_WRITE | MAY_EXEC)) != 0){
 808                 iput(old_dir);
 809                 iput(new_dir);
 810                 return error;
 811         }
 812         if (!new_len || (new_base[0] == '.' &&
 813             (new_len == 1 || (new_base[1] == '.' &&
 814              new_len == 2)))) {
 815                 iput(old_dir);
 816                 iput(new_dir);
 817                 return -EPERM;
 818         }
 819         if (new_dir->i_dev != old_dir->i_dev) {
 820                 iput(old_dir);
 821                 iput(new_dir);
 822                 return -EXDEV;
 823         }
 824         if (IS_RDONLY(new_dir) || IS_RDONLY(old_dir)) {
 825                 iput(old_dir);
 826                 iput(new_dir);
 827                 return -EROFS;
 828         }
 829         /*
 830          * A file cannot be removed from an append-only directory
 831          */
 832         if (IS_APPEND(old_dir)) {
 833                 iput(old_dir);
 834                 iput(new_dir);
 835                 return -EPERM;
 836         }
 837         if (!old_dir->i_op || !old_dir->i_op->rename) {
 838                 iput(old_dir);
 839                 iput(new_dir);
 840                 return -EPERM;
 841         }
 842         new_dir->i_count++;
 843         if (new_dir->i_sb && new_dir->i_sb->dq_op)
 844                 new_dir->i_sb->dq_op->initialize(new_dir, -1);
 845         down(&new_dir->i_sem);
 846         error = old_dir->i_op->rename(old_dir, old_base, old_len, 
 847                 new_dir, new_base, new_len);
 848         up(&new_dir->i_sem);
 849         iput(new_dir);
 850         return error;
 851 }
 852 
 853 asmlinkage int sys_rename(const char * oldname, const char * newname)
     /*  */
 854 {
 855         int error;
 856         char * from, * to;
 857 
 858         error = getname(oldname,&from);
 859         if (!error) {
 860                 error = getname(newname,&to);
 861                 if (!error) {
 862                         error = do_rename(from,to);
 863                         putname(to);
 864                 }
 865                 putname(from);
 866         }
 867         return error;
 868 }
/* */
root/fs/namei.c

DEFINITIONS
