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_ISBLK(inode->i_mode) || S_ISCHR(inode->i_mode)) {
 400                 if (IS_NODEV(inode)) {
 401                         iput(inode);
 402                         return -EACCES;
 403                 }
 404                 flag &= ~O_TRUNC;
 405         } else {
 406                 if (IS_RDONLY(inode) && (flag & 2)) {
 407                         iput(inode);
 408                         return -EROFS;
 409                 }
 410         }
 411         /*
 412          * An append-only file must be opened in append mode for writing
 413          */
 414         if (IS_APPEND(inode) && ((flag & FMODE_WRITE) && !(flag & O_APPEND))) {
 415                 iput(inode);
 416                 return -EPERM;
 417         }
 418         if (flag & O_TRUNC) {
 419                 struct iattr newattrs;
 420 
 421                 if ((error = get_write_access(inode))) {
 422                         iput(inode);
 423                         return error;
 424                 }
 425                 if (inode->i_sb && inode->i_sb->dq_op)
 426                         inode->i_sb->dq_op->initialize(inode, -1);
 427                 newattrs.ia_size = 0;
 428                 newattrs.ia_valid = ATTR_SIZE;
 429                 if ((error = notify_change(inode, &newattrs))) {
 430                         put_write_access(inode);
 431                         iput(inode);
 432                         return error;
 433                 }
 434                 down(&inode->i_sem);
 435                 inode->i_size = 0;
 436                 if (inode->i_op && inode->i_op->truncate)
 437                         inode->i_op->truncate(inode);
 438                 up(&inode->i_sem);
 439                 inode->i_dirt = 1;
 440                 put_write_access(inode);
 441         } else
 442                 if (flag & FMODE_WRITE)
 443                         if (inode->i_sb && inode->i_sb->dq_op)
 444                                 inode->i_sb->dq_op->initialize(inode, -1);
 445         *res_inode = inode;
 446         return 0;
 447 }
 448 
 449 int do_mknod(const char * filename, int mode, dev_t dev)
     /*  */
 450 {
 451         const char * basename;
 452         int namelen, error;
 453         struct inode * dir;
 454 
 455         mode &= ~current->fs->umask;
 456         error = dir_namei(filename, &namelen, &basename, NULL, &dir);
 457         if (error)
 458                 return error;
 459         if (!namelen) {
 460                 iput(dir);
 461                 return -ENOENT;
 462         }
 463         if (IS_RDONLY(dir)) {
 464                 iput(dir);
 465                 return -EROFS;
 466         }
 467         if ((error = permission(dir,MAY_WRITE | MAY_EXEC)) != 0) {
 468                 iput(dir);
 469                 return error;
 470         }
 471         if (!dir->i_op || !dir->i_op->mknod) {
 472                 iput(dir);
 473                 return -EPERM;
 474         }
 475         dir->i_count++;
 476         if (dir->i_sb && dir->i_sb->dq_op)
 477                 dir->i_sb->dq_op->initialize(dir, -1);
 478         down(&dir->i_sem);
 479         error = dir->i_op->mknod(dir,basename,namelen,mode,dev);
 480         up(&dir->i_sem);
 481         iput(dir);
 482         return error;
 483 }
 484 
 485 asmlinkage int sys_mknod(const char * filename, int mode, dev_t dev)
     /*  */
 486 {
 487         int error;
 488         char * tmp;
 489 
 490         if (S_ISDIR(mode) || (!S_ISFIFO(mode) && !fsuser()))
 491                 return -EPERM;
 492         switch (mode & S_IFMT) {
 493         case 0:
 494                 mode |= S_IFREG;
 495                 break;
 496         case S_IFREG: case S_IFCHR: case S_IFBLK: case S_IFIFO: case S_IFSOCK:
 497                 break;
 498         default:
 499                 return -EINVAL;
 500         }
 501         error = getname(filename,&tmp);
 502         if (!error) {
 503                 error = do_mknod(tmp,mode,dev);
 504                 putname(tmp);
 505         }
 506         return error;
 507 }
 508 
 509 static int do_mkdir(const char * pathname, int mode)
     /*  */
 510 {
 511         const char * basename;
 512         int namelen, error;
 513         struct inode * dir;
 514 
 515         error = dir_namei(pathname, &namelen, &basename, NULL, &dir);
 516         if (error)
 517                 return error;
 518         if (!namelen) {
 519                 iput(dir);
 520                 return -ENOENT;
 521         }
 522         if (IS_RDONLY(dir)) {
 523                 iput(dir);
 524                 return -EROFS;
 525         }
 526         if ((error = permission(dir,MAY_WRITE | MAY_EXEC)) != 0) {
 527                 iput(dir);
 528                 return error;
 529         }
 530         if (!dir->i_op || !dir->i_op->mkdir) {
 531                 iput(dir);
 532                 return -EPERM;
 533         }
 534         dir->i_count++;
 535         if (dir->i_sb && dir->i_sb->dq_op)
 536                 dir->i_sb->dq_op->initialize(dir, -1);
 537         down(&dir->i_sem);
 538         error = dir->i_op->mkdir(dir, basename, namelen, mode & 0777 & ~current->fs->umask);
 539         up(&dir->i_sem);
 540         iput(dir);
 541         return error;
 542 }
 543 
 544 asmlinkage int sys_mkdir(const char * pathname, int mode)
     /*  */
 545 {
 546         int error;
 547         char * tmp;
 548 
 549         error = getname(pathname,&tmp);
 550         if (!error) {
 551                 error = do_mkdir(tmp,mode);
 552                 putname(tmp);
 553         }
 554         return error;
 555 }
 556 
 557 static int do_rmdir(const char * name)
     /*  */
 558 {
 559         const char * basename;
 560         int namelen, error;
 561         struct inode * dir;
 562 
 563         error = dir_namei(name, &namelen, &basename, NULL, &dir);
 564         if (error)
 565                 return error;
 566         if (!namelen) {
 567                 iput(dir);
 568                 return -ENOENT;
 569         }
 570         if (IS_RDONLY(dir)) {
 571                 iput(dir);
 572                 return -EROFS;
 573         }
 574         if ((error = permission(dir,MAY_WRITE | MAY_EXEC)) != 0) {
 575                 iput(dir);
 576                 return error;
 577         }
 578         /*
 579          * A subdirectory cannot be removed from an append-only directory
 580          */
 581         if (IS_APPEND(dir)) {
 582                 iput(dir);
 583                 return -EPERM;
 584         }
 585         if (!dir->i_op || !dir->i_op->rmdir) {
 586                 iput(dir);
 587                 return -EPERM;
 588         }
 589         if (dir->i_sb && dir->i_sb->dq_op)
 590                 dir->i_sb->dq_op->initialize(dir, -1);
 591         return dir->i_op->rmdir(dir,basename,namelen);
 592 }
 593 
 594 asmlinkage int sys_rmdir(const char * pathname)
     /*  */
 595 {
 596         int error;
 597         char * tmp;
 598 
 599         error = getname(pathname,&tmp);
 600         if (!error) {
 601                 error = do_rmdir(tmp);
 602                 putname(tmp);
 603         }
 604         return error;
 605 }
 606 
 607 static int do_unlink(const char * name)
     /*  */
 608 {
 609         const char * basename;
 610         int namelen, error;
 611         struct inode * dir;
 612 
 613         error = dir_namei(name, &namelen, &basename, NULL, &dir);
 614         if (error)
 615                 return error;
 616         if (!namelen) {
 617                 iput(dir);
 618                 return -EPERM;
 619         }
 620         if (IS_RDONLY(dir)) {
 621                 iput(dir);
 622                 return -EROFS;
 623         }
 624         if ((error = permission(dir,MAY_WRITE | MAY_EXEC)) != 0) {
 625                 iput(dir);
 626                 return error;
 627         }
 628         /*
 629          * A file cannot be removed from an append-only directory
 630          */
 631         if (IS_APPEND(dir)) {
 632                 iput(dir);
 633                 return -EPERM;
 634         }
 635         if (!dir->i_op || !dir->i_op->unlink) {
 636                 iput(dir);
 637                 return -EPERM;
 638         }
 639         if (dir->i_sb && dir->i_sb->dq_op)
 640                 dir->i_sb->dq_op->initialize(dir, -1);
 641         return dir->i_op->unlink(dir,basename,namelen);
 642 }
 643 
 644 asmlinkage int sys_unlink(const char * pathname)
     /*  */
 645 {
 646         int error;
 647         char * tmp;
 648 
 649         error = getname(pathname,&tmp);
 650         if (!error) {
 651                 error = do_unlink(tmp);
 652                 putname(tmp);
 653         }
 654         return error;
 655 }
 656 
 657 static int do_symlink(const char * oldname, const char * newname)
     /*  */
 658 {
 659         struct inode * dir;
 660         const char * basename;
 661         int namelen, error;
 662 
 663         error = dir_namei(newname, &namelen, &basename, NULL, &dir);
 664         if (error)
 665                 return error;
 666         if (!namelen) {
 667                 iput(dir);
 668                 return -ENOENT;
 669         }
 670         if (IS_RDONLY(dir)) {
 671                 iput(dir);
 672                 return -EROFS;
 673         }
 674         if ((error = permission(dir,MAY_WRITE | MAY_EXEC)) != 0) {
 675                 iput(dir);
 676                 return error;
 677         }
 678         if (!dir->i_op || !dir->i_op->symlink) {
 679                 iput(dir);
 680                 return -EPERM;
 681         }
 682         dir->i_count++;
 683         if (dir->i_sb && dir->i_sb->dq_op)
 684                 dir->i_sb->dq_op->initialize(dir, -1);
 685         down(&dir->i_sem);
 686         error = dir->i_op->symlink(dir,basename,namelen,oldname);
 687         up(&dir->i_sem);
 688         iput(dir);
 689         return error;
 690 }
 691 
 692 asmlinkage int sys_symlink(const char * oldname, const char * newname)
     /*  */
 693 {
 694         int error;
 695         char * from, * to;
 696 
 697         error = getname(oldname,&from);
 698         if (!error) {
 699                 error = getname(newname,&to);
 700                 if (!error) {
 701                         error = do_symlink(from,to);
 702                         putname(to);
 703                 }
 704                 putname(from);
 705         }
 706         return error;
 707 }
 708 
 709 static int do_link(struct inode * oldinode, const char * newname)
     /*  */
 710 {
 711         struct inode * dir;
 712         const char * basename;
 713         int namelen, error;
 714 
 715         error = dir_namei(newname, &namelen, &basename, NULL, &dir);
 716         if (error) {
 717                 iput(oldinode);
 718                 return error;
 719         }
 720         if (!namelen) {
 721                 iput(oldinode);
 722                 iput(dir);
 723                 return -EPERM;
 724         }
 725         if (IS_RDONLY(dir)) {
 726                 iput(oldinode);
 727                 iput(dir);
 728                 return -EROFS;
 729         }
 730         if (dir->i_dev != oldinode->i_dev) {
 731                 iput(dir);
 732                 iput(oldinode);
 733                 return -EXDEV;
 734         }
 735         if ((error = permission(dir,MAY_WRITE | MAY_EXEC)) != 0) {
 736                 iput(dir);
 737                 iput(oldinode);
 738                 return error;
 739         }
 740         /*
 741          * A link to an append-only or immutable file cannot be created
 742          */
 743         if (IS_APPEND(oldinode) || IS_IMMUTABLE(oldinode)) {
 744                 iput(dir);
 745                 iput(oldinode);
 746                 return -EPERM;
 747         }
 748         if (!dir->i_op || !dir->i_op->link) {
 749                 iput(dir);
 750                 iput(oldinode);
 751                 return -EPERM;
 752         }
 753         dir->i_count++;
 754         if (dir->i_sb && dir->i_sb->dq_op)
 755                 dir->i_sb->dq_op->initialize(dir, -1);
 756         down(&dir->i_sem);
 757         error = dir->i_op->link(oldinode, dir, basename, namelen);
 758         up(&dir->i_sem);
 759         iput(dir);
 760         return error;
 761 }
 762 
 763 asmlinkage int sys_link(const char * oldname, const char * newname)
     /*  */
 764 {
 765         int error;
 766         char * to;
 767         struct inode * oldinode;
 768 
 769         error = namei(oldname, &oldinode);
 770         if (error)
 771                 return error;
 772         error = getname(newname,&to);
 773         if (error) {
 774                 iput(oldinode);
 775                 return error;
 776         }
 777         error = do_link(oldinode,to);
 778         putname(to);
 779         return error;
 780 }
 781 
 782 static int do_rename(const char * oldname, const char * newname)
     /*  */
 783 {
 784         struct inode * old_dir, * new_dir;
 785         const char * old_base, * new_base;
 786         int old_len, new_len, error;
 787 
 788         error = dir_namei(oldname, &old_len, &old_base, NULL, &old_dir);
 789         if (error)
 790                 return error;
 791         if ((error = permission(old_dir,MAY_WRITE | MAY_EXEC)) != 0) {
 792                 iput(old_dir);
 793                 return error;
 794         }
 795         if (!old_len || (old_base[0] == '.' &&
 796             (old_len == 1 || (old_base[1] == '.' &&
 797              old_len == 2)))) {
 798                 iput(old_dir);
 799                 return -EPERM;
 800         }
 801         error = dir_namei(newname, &new_len, &new_base, NULL, &new_dir);
 802         if (error) {
 803                 iput(old_dir);
 804                 return error;
 805         }
 806         if ((error = permission(new_dir,MAY_WRITE | MAY_EXEC)) != 0){
 807                 iput(old_dir);
 808                 iput(new_dir);
 809                 return error;
 810         }
 811         if (!new_len || (new_base[0] == '.' &&
 812             (new_len == 1 || (new_base[1] == '.' &&
 813              new_len == 2)))) {
 814                 iput(old_dir);
 815                 iput(new_dir);
 816                 return -EPERM;
 817         }
 818         if (new_dir->i_dev != old_dir->i_dev) {
 819                 iput(old_dir);
 820                 iput(new_dir);
 821                 return -EXDEV;
 822         }
 823         if (IS_RDONLY(new_dir) || IS_RDONLY(old_dir)) {
 824                 iput(old_dir);
 825                 iput(new_dir);
 826                 return -EROFS;
 827         }
 828         /*
 829          * A file cannot be removed from an append-only directory
 830          */
 831         if (IS_APPEND(old_dir)) {
 832                 iput(old_dir);
 833                 iput(new_dir);
 834                 return -EPERM;
 835         }
 836         if (!old_dir->i_op || !old_dir->i_op->rename) {
 837                 iput(old_dir);
 838                 iput(new_dir);
 839                 return -EPERM;
 840         }
 841         new_dir->i_count++;
 842         if (new_dir->i_sb && new_dir->i_sb->dq_op)
 843                 new_dir->i_sb->dq_op->initialize(new_dir, -1);
 844         down(&new_dir->i_sem);
 845         error = old_dir->i_op->rename(old_dir, old_base, old_len, 
 846                 new_dir, new_base, new_len);
 847         up(&new_dir->i_sem);
 848         iput(new_dir);
 849         return error;
 850 }
 851 
 852 asmlinkage int sys_rename(const char * oldname, const char * newname)
     /*  */
 853 {
 854         int error;
 855         char * from, * to;
 856 
 857         error = getname(oldname,&from);
 858         if (!error) {
 859                 error = getname(newname,&to);
 860                 if (!error) {
 861                         error = do_rename(from,to);
 862                         putname(to);
 863                 }
 864                 putname(from);
 865         }
 866         return error;
 867 }
/* */
root/fs/namei.c

DEFINITIONS
