fs/open.c

   1 /*
   2  *  linux/fs/open.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 #include <linux/mm.h>
   8 #include <linux/utime.h>
   9 #include <linux/file.h>
  10 #include <linux/smp_lock.h>
  11 #include <linux/quotaops.h>
  12
  13 #include <asm/uaccess.h>
  14
  15 asmlinkage long sys_statfs(const char * path, struct statfs * buf)
  16 {
  17         struct dentry * dentry;
  18         int error;
  19
  20         lock_kernel();
  21         dentry = namei(path);
  22         error = PTR_ERR(dentry);
  23         if (!IS_ERR(dentry)) {
  24                 struct inode * inode = dentry->d_inode;
  25                 struct super_block * sb = inode->i_sb;
  26
  27                 error = -ENODEV;
  28                 if (sb && sb->s_op && sb->s_op->statfs)
  29                         error = sb->s_op->statfs(sb, buf, sizeof(struct statfs));
  30
  31                 dput(dentry);
  32         }
  33         unlock_kernel();
  34         return error;
  35 }
  36
  37 asmlinkage long sys_fstatfs(unsigned int fd, struct statfs * buf)
  38 {
  39         struct file * file;
  40         struct super_block * sb;
  41         int error;
  42
  43         error = -EBADF;
  44         file = fget(fd);
  45         if (!file)
  46                 goto out;
  47         error = -ENODEV;
  48         sb = file->f_dentry->d_inode->i_sb;
  49         lock_kernel();
  50         if (sb && sb->s_op && sb->s_op->statfs)
  51                 error = sb->s_op->statfs(sb, buf, sizeof(struct statfs));
  52         unlock_kernel();
  53         fput(file);
  54 out:
  55         return error;
  56 }
  57
  58 int do_truncate(struct dentry *dentry, loff_t length)
  59 {
  60         struct inode *inode = dentry->d_inode;
  61         int error;
  62         struct iattr newattrs;
  63
  64         /* Not pretty: "inode->i_size" shouldn't really be signed. But it is. */
  65         if (length < 0)
  66                 return -EINVAL;
  67
  68         down(&inode->i_sem);
  69         newattrs.ia_size = length;
  70         newattrs.ia_valid = ATTR_SIZE | ATTR_CTIME;
  71         error = notify_change(dentry, &newattrs);
  72         up(&inode->i_sem);
  73         return error;
  74 }
  75
  76 static inline long do_sys_truncate(const char * path, loff_t length)
  77 {
  78         struct dentry * dentry;
  79         struct inode * inode;
  80         int error;
  81
  82         lock_kernel();
  83
  84         error = -EINVAL;
  85         if (length < 0) /* sorry, but loff_t says... */
  86                 goto out;
  87
  88         dentry = namei(path);
  89
  90         error = PTR_ERR(dentry);
  91         if (IS_ERR(dentry))
  92                 goto out;
  93         inode = dentry->d_inode;
  94
  95         error = -EACCES;
  96         if (S_ISDIR(inode->i_mode))
  97                 goto dput_and_out;
  98
  99         error = permission(inode,MAY_WRITE);
 100         if (error)
 101                 goto dput_and_out;
 102
 103         error = -EROFS;
 104         if (IS_RDONLY(inode))
 105                 goto dput_and_out;
 106
 107         error = -EPERM;
 108         if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
 109                 goto dput_and_out;
 110
 111         error = get_write_access(inode);
 112         if (error)
 113                 goto dput_and_out;
 114
 115         error = locks_verify_truncate(inode, NULL, length);
 116         if (!error) {
 117                 DQUOT_INIT(inode);
 118                 error = do_truncate(dentry, length);
 119         }
 120         put_write_access(inode);
 121 dput_and_out:
 122         dput(dentry);
 123 out:
 124         unlock_kernel();
 125         return error;
 126 }
 127
 128 asmlinkage long sys_truncate(const char * path, unsigned long length)
 129 {
 130         return do_sys_truncate(path, length);
 131 }
 132
 133 static inline long do_sys_ftruncate(unsigned int fd, loff_t length)
 134 {
 135         struct inode * inode;
 136         struct dentry *dentry;
 137         struct file * file;
 138         int error;
 139
 140         error = -EINVAL;
 141         if (length < 0)
 142                 goto out;
 143         error = -EBADF;
 144         file = fget(fd);
 145         if (!file)
 146                 goto out;
 147         error = -ENOENT;
 148         if (!(dentry = file->f_dentry))
 149                 goto out_putf;
 150         if (!(inode = dentry->d_inode))
 151                 goto out_putf;
 152         error = -EACCES;
 153         if (S_ISDIR(inode->i_mode) || !(file->f_mode & FMODE_WRITE))
 154                 goto out_putf;
 155         error = -EPERM;
 156         if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
 157                 goto out_putf;
 158         error = locks_verify_truncate(inode, file, length);
 159         lock_kernel();
 160         if (!error)
 161                 error = do_truncate(dentry, length);
 162         unlock_kernel();
 163 out_putf:
 164         fput(file);
 165 out:
 166         return error;
 167 }
 168
 169 asmlinkage long sys_ftruncate(unsigned int fd, unsigned long length)
 170 {
 171         return do_sys_ftruncate(fd, length);
 172 }
 173
 174 /* LFS versions of truncate are only needed on 32 bit machines */
 175 #if BITS_PER_LONG == 32
 176 asmlinkage long sys_truncate64(const char * path, loff_t length)
 177 {
 178         return do_sys_truncate(path, length);
 179 }
 180
 181 asmlinkage long sys_ftruncate64(unsigned int fd, loff_t length)
 182 {
 183         return do_sys_ftruncate(fd, length);
 184 }
 185 #endif
 186
 187 #if !(defined(__alpha__) || defined(__ia64__))
 188
 189 /*
 190  * sys_utime() can be implemented in user-level using sys_utimes().
 191  * Is this for backwards compatibility?  If so, why not move it
 192  * into the appropriate arch directory (for those architectures that
 193  * need it).
 194  */
 195
 196 /* If times==NULL, set access and modification to current time,
 197  * must be owner or have write permission.
 198  * Else, update from *times, must be owner or super user.
 199  */
 200 asmlinkage long sys_utime(char * filename, struct utimbuf * times)
 201 {
 202         int error;
 203         struct dentry * dentry;
 204         struct inode * inode;
 205         struct iattr newattrs;
 206
 207         lock_kernel();
 208         dentry = namei(filename);
 209
 210         error = PTR_ERR(dentry);
 211         if (IS_ERR(dentry))
 212                 goto out;
 213         inode = dentry->d_inode;
 214
 215         error = -EROFS;
 216         if (IS_RDONLY(inode))
 217                 goto dput_and_out;
 218
 219         /* Don't worry, the checks are done in inode_change_ok() */
 220         newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
 221         if (times) {
 222                 error = get_user(newattrs.ia_atime, &times->actime);
 223                 if (!error)
 224                         error = get_user(newattrs.ia_mtime, &times->modtime);
 225                 if (error)
 226                         goto dput_and_out;
 227
 228                 newattrs.ia_valid |= ATTR_ATIME_SET | ATTR_MTIME_SET;
 229         } else {
 230                 if (current->fsuid != inode->i_uid &&
 231                     (error = permission(inode,MAY_WRITE)) != 0)
 232                         goto dput_and_out;
 233         }
 234         error = notify_change(dentry, &newattrs);
 235 dput_and_out:
 236         dput(dentry);
 237 out:
 238         unlock_kernel();
 239         return error;
 240 }
 241
 242 #endif
 243
 244 /* If times==NULL, set access and modification to current time,
 245  * must be owner or have write permission.
 246  * Else, update from *times, must be owner or super user.
 247  */
 248 asmlinkage long sys_utimes(char * filename, struct timeval * utimes)
 249 {
 250         int error;
 251         struct dentry * dentry;
 252         struct inode * inode;
 253         struct iattr newattrs;
 254
 255         lock_kernel();
 256         dentry = namei(filename);
 257
 258         error = PTR_ERR(dentry);
 259         if (IS_ERR(dentry))
 260                 goto out;
 261         inode = dentry->d_inode;
 262
 263         error = -EROFS;
 264         if (IS_RDONLY(inode))
 265                 goto dput_and_out;
 266
 267         /* Don't worry, the checks are done in inode_change_ok() */
 268         newattrs.ia_valid = ATTR_CTIME | ATTR_MTIME | ATTR_ATIME;
 269         if (utimes) {
 270                 struct timeval times[2];
 271                 error = -EFAULT;
 272                 if (copy_from_user(&times, utimes, sizeof(times)))
 273                         goto dput_and_out;
 274                 newattrs.ia_atime = times[0].tv_sec;
 275                 newattrs.ia_mtime = times[1].tv_sec;
 276                 newattrs.ia_valid |= ATTR_ATIME_SET | ATTR_MTIME_SET;
 277         } else {
 278                 if ((error = permission(inode,MAY_WRITE)) != 0)
 279                         goto dput_and_out;
 280         }
 281         error = notify_change(dentry, &newattrs);
 282 dput_and_out:
 283         dput(dentry);
 284 out:
 285         unlock_kernel();
 286         return error;
 287 }
 288
 289 /*
 290  * access() needs to use the real uid/gid, not the effective uid/gid.
 291  * We do this by temporarily clearing all FS-related capabilities and
 292  * switching the fsuid/fsgid around to the real ones.
 293  */
 294 asmlinkage long sys_access(const char * filename, int mode)
 295 {
 296         struct dentry * dentry;
 297         int old_fsuid, old_fsgid;
 298         kernel_cap_t old_cap;
 299         int res;
 300
 301         if (mode & ~S_IRWXO)    /* where's F_OK, X_OK, W_OK, R_OK? */
 302                 return -EINVAL;
 303
 304         lock_kernel();
 305         old_fsuid = current->fsuid;
 306         old_fsgid = current->fsgid;
 307         old_cap = current->cap_effective;
 308
 309         current->fsuid = current->uid;
 310         current->fsgid = current->gid;
 311
 312         /* Clear the capabilities if we switch to a non-root user */
 313         if (current->uid)
 314                 cap_clear(current->cap_effective);
 315         else
 316                 current->cap_effective = current->cap_permitted;
 317
 318         dentry = namei(filename);
 319         res = PTR_ERR(dentry);
 320         if (!IS_ERR(dentry)) {
 321                 res = permission(dentry->d_inode, mode);
 322                 /* SuS v2 requires we report a read only fs too */
 323                 if(!res && (mode & S_IWOTH) && IS_RDONLY(dentry->d_inode))
 324                         res = -EROFS;
 325                 dput(dentry);
 326         }
 327
 328         current->fsuid = old_fsuid;
 329         current->fsgid = old_fsgid;
 330         current->cap_effective = old_cap;
 331
 332         unlock_kernel();
 333         return res;
 334 }
 335
 336 asmlinkage long sys_chdir(const char * filename)
 337 {
 338         int error;
 339         struct inode *inode;
 340         struct dentry *dentry, *tmp;
 341
 342         lock_kernel();
 343
 344         dentry = namei(filename);
 345         error = PTR_ERR(dentry);
 346         if (IS_ERR(dentry))
 347                 goto out;
 348
 349         inode = dentry->d_inode;
 350
 351         error = -ENOTDIR;
 352         if (!S_ISDIR(inode->i_mode))
 353                 goto dput_and_out;
 354
 355         error = permission(inode,MAY_EXEC);
 356         if (error)
 357                 goto dput_and_out;
 358
 359         /* exchange dentries */
 360         tmp = current->fs->pwd;
 361         current->fs->pwd = dentry;
 362         dentry = tmp;
 363
 364 dput_and_out:
 365         dput(dentry);
 366 out:
 367         unlock_kernel();
 368         return error;
 369 }
 370
 371 asmlinkage long sys_fchdir(unsigned int fd)
 372 {
 373         struct file *file;
 374         struct dentry *dentry;
 375         struct inode *inode;
 376         int error;
 377
 378         error = -EBADF;
 379         file = fget(fd);
 380         if (!file)
 381                 goto out;
 382
 383         error = -ENOENT;
 384         if (!(dentry = file->f_dentry))
 385                 goto out_putf;
 386         if (!(inode = dentry->d_inode))
 387                 goto out_putf;
 388
 389         error = -ENOTDIR;
 390         if (!S_ISDIR(inode->i_mode))
 391                 goto out_putf;
 392
 393         lock_kernel();
 394         error = permission(inode, MAY_EXEC);
 395         if (!error) {
 396                 struct dentry *tmp = current->fs->pwd;
 397                 current->fs->pwd = dget(dentry);
 398                 dput(tmp);
 399         }
 400         unlock_kernel();
 401 out_putf:
 402         fput(file);
 403 out:
 404         return error;
 405 }
 406
 407 asmlinkage long sys_chroot(const char * filename)
 408 {
 409         int error;
 410         struct inode *inode;
 411         struct dentry *dentry, *tmp;
 412
 413         lock_kernel();
 414
 415         dentry = namei(filename);
 416         error = PTR_ERR(dentry);
 417         if (IS_ERR(dentry))
 418                 goto out;
 419
 420         inode = dentry->d_inode;
 421
 422         error = -ENOTDIR;
 423         if (!S_ISDIR(inode->i_mode))
 424                 goto dput_and_out;
 425
 426         error = permission(inode,MAY_EXEC);
 427         if (error)
 428                 goto dput_and_out;
 429
 430         error = -EPERM;
 431         if (!capable(CAP_SYS_CHROOT))
 432                 goto dput_and_out;
 433
 434         /* exchange dentries */
 435         tmp = current->fs->root;
 436         current->fs->root = dentry;
 437         dentry = tmp;
 438         error = 0;
 439
 440 dput_and_out:
 441         dput(dentry);
 442 out:
 443         unlock_kernel();
 444         return error;
 445 }
 446
 447 asmlinkage long sys_fchmod(unsigned int fd, mode_t mode)
 448 {
 449         struct inode * inode;
 450         struct dentry * dentry;
 451         struct file * file;
 452         int err = -EBADF;
 453         struct iattr newattrs;
 454
 455         file = fget(fd);
 456         if (!file)
 457                 goto out;
 458
 459         err = -ENOENT;
 460         if (!(dentry = file->f_dentry))
 461                 goto out_putf;
 462         if (!(inode = dentry->d_inode))
 463                 goto out_putf;
 464
 465         err = -EROFS;
 466         if (IS_RDONLY(inode))
 467                 goto out_putf;
 468         err = -EPERM;
 469         if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
 470                 goto out_putf;
 471         if (mode == (mode_t) -1)
 472                 mode = inode->i_mode;
 473         newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
 474         newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
 475         lock_kernel();
 476         err = notify_change(dentry, &newattrs);
 477         unlock_kernel();
 478
 479 out_putf:
 480         fput(file);
 481 out:
 482         return err;
 483 }
 484
 485 asmlinkage long sys_chmod(const char * filename, mode_t mode)
 486 {
 487         struct dentry * dentry;
 488         struct inode * inode;
 489         int error;
 490         struct iattr newattrs;
 491
 492         lock_kernel();
 493         dentry = namei(filename);
 494
 495         error = PTR_ERR(dentry);
 496         if (IS_ERR(dentry))
 497                 goto out;
 498         inode = dentry->d_inode;
 499
 500         error = -EROFS;
 501         if (IS_RDONLY(inode))
 502                 goto dput_and_out;
 503
 504         error = -EPERM;
 505         if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
 506                 goto dput_and_out;
 507
 508         if (mode == (mode_t) -1)
 509                 mode = inode->i_mode;
 510         newattrs.ia_mode = (mode & S_IALLUGO) | (inode->i_mode & ~S_IALLUGO);
 511         newattrs.ia_valid = ATTR_MODE | ATTR_CTIME;
 512         error = notify_change(dentry, &newattrs);
 513
 514 dput_and_out:
 515         dput(dentry);
 516 out:
 517         unlock_kernel();
 518         return error;
 519 }
 520
 521 static int chown_common(struct dentry * dentry, uid_t user, gid_t group)
 522 {
 523         struct inode * inode;
 524         int error;
 525         struct iattr newattrs;
 526
 527         error = -ENOENT;
 528         if (!(inode = dentry->d_inode)) {
 529                 printk("chown_common: NULL inode\n");
 530                 goto out;
 531         }
 532         error = -EROFS;
 533         if (IS_RDONLY(inode))
 534                 goto out;
 535         error = -EPERM;
 536         if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
 537                 goto out;
 538         if (user == (uid_t) -1)
 539                 user = inode->i_uid;
 540         if (group == (gid_t) -1)
 541                 group = inode->i_gid;
 542         newattrs.ia_mode = inode->i_mode;
 543         newattrs.ia_uid = user;
 544         newattrs.ia_gid = group;
 545         newattrs.ia_valid =  ATTR_UID | ATTR_GID | ATTR_CTIME;
 546         /*
 547          * If the user or group of a non-directory has been changed by a
 548          * non-root user, remove the setuid bit.
 549          * 19981026     David C Niemi <niemi@tux.org>
 550          *
 551          * Changed this to apply to all users, including root, to avoid
 552          * some races. This is the behavior we had in 2.0. The check for
 553          * non-root was definitely wrong for 2.2 anyway, as it should
 554          * have been using CAP_FSETID rather than fsuid -- 19990830 SD.
 555          */
 556         if ((inode->i_mode & S_ISUID) == S_ISUID &&
 557                 !S_ISDIR(inode->i_mode))
 558         {
 559                 newattrs.ia_mode &= ~S_ISUID;
 560                 newattrs.ia_valid |= ATTR_MODE;
 561         }
 562         /*
 563          * Likewise, if the user or group of a non-directory has been changed
 564          * by a non-root user, remove the setgid bit UNLESS there is no group
 565          * execute bit (this would be a file marked for mandatory locking).
 566          * 19981026     David C Niemi <niemi@tux.org>
 567          *
 568          * Removed the fsuid check (see the comment above) -- 19990830 SD.
 569          */
 570         if (((inode->i_mode & (S_ISGID | S_IXGRP)) == (S_ISGID | S_IXGRP))
 571                 && !S_ISDIR(inode->i_mode))
 572         {
 573                 newattrs.ia_mode &= ~S_ISGID;
 574                 newattrs.ia_valid |= ATTR_MODE;
 575         }
 576         error = DQUOT_TRANSFER(dentry, &newattrs);
 577 out:
 578         return error;
 579 }
 580
 581 asmlinkage long sys_chown(const char * filename, uid_t user, gid_t group)
 582 {
 583         struct dentry * dentry;
 584         int error;
 585
 586         lock_kernel();
 587         dentry = namei(filename);
 588
 589         error = PTR_ERR(dentry);
 590         if (!IS_ERR(dentry)) {
 591                 error = chown_common(dentry, user, group);
 592                 dput(dentry);
 593         }
 594         unlock_kernel();
 595         return error;
 596 }
 597
 598 asmlinkage long sys_lchown(const char * filename, uid_t user, gid_t group)
 599 {
 600         struct dentry * dentry;
 601         int error;
 602
 603         lock_kernel();
 604         dentry = lnamei(filename);
 605
 606         error = PTR_ERR(dentry);
 607         if (!IS_ERR(dentry)) {
 608                 error = chown_common(dentry, user, group);
 609                 dput(dentry);
 610         }
 611         unlock_kernel();
 612         return error;
 613 }
 614
 615
 616 asmlinkage long sys_fchown(unsigned int fd, uid_t user, gid_t group)
 617 {
 618         struct dentry * dentry;
 619         struct file * file;
 620         int error = -EBADF;
 621
 622         file = fget(fd);
 623         if (!file)
 624                 goto out;
 625         error = -ENOENT;
 626         lock_kernel();
 627         if ((dentry = file->f_dentry) != NULL)
 628                 error = chown_common(dentry, user, group);
 629         unlock_kernel();
 630         fput(file);
 631
 632 out:
 633         return error;
 634 }
 635
 636 /*
 637  * Note that while the flag value (low two bits) for sys_open means:
 638  *      00 - read-only
 639  *      01 - write-only
 640  *      10 - read-write
 641  *      11 - special
 642  * it is changed into
 643  *      00 - no permissions needed
 644  *      01 - read-permission
 645  *      10 - write-permission
 646  *      11 - read-write
 647  * for the internal routines (ie open_namei()/follow_link() etc). 00 is
 648  * used by symlinks.
 649  */
 650 struct file *filp_open(const char * filename, int flags, int mode)
 651 {
 652         struct inode * inode;
 653         struct dentry * dentry;
 654         struct file * f;
 655         int flag,error;
 656
 657         error = -ENFILE;
 658         f = get_empty_filp();
 659         if (!f)
 660                 goto out;
 661         f->f_flags = flag = flags;
 662         f->f_mode = (flag+1) & O_ACCMODE;
 663         if (f->f_mode)
 664                 flag++;
 665         if (flag & O_TRUNC)
 666                 flag |= 2;
 667         dentry = open_namei(filename,flag,mode);
 668         error = PTR_ERR(dentry);
 669         if (IS_ERR(dentry))
 670                 goto cleanup_file;
 671         inode = dentry->d_inode;
 672         if (f->f_mode & FMODE_WRITE) {
 673                 error = get_write_access(inode);
 674                 if (error)
 675                         goto cleanup_dentry;
 676         }
 677
 678         f->f_dentry = dentry;
 679         f->f_pos = 0;
 680         f->f_reada = 0;
 681         f->f_op = NULL;
 682         if (inode->i_op)
 683                 f->f_op = inode->i_op->default_file_ops;
 684         if (inode->i_sb)
 685                 file_move(f, &inode->i_sb->s_files);
 686         if (f->f_op && f->f_op->open) {
 687                 error = f->f_op->open(inode,f);
 688                 if (error)
 689                         goto cleanup_all;
 690         }
 691         f->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
 692
 693         return f;
 694
 695 cleanup_all:
 696         if (f->f_mode & FMODE_WRITE)
 697                 put_write_access(inode);
 698 cleanup_dentry:
 699         f->f_dentry = NULL;
 700         dput(dentry);
 701 cleanup_file:
 702         put_filp(f);
 703 out:
 704         return ERR_PTR(error);
 705 }
 706
 707 /*
 708  * Find an empty file descriptor entry, and mark it busy.
 709  */
 710 int get_unused_fd(void)
 711 {
 712         struct files_struct * files = current->files;
 713         int fd, error;
 714
 715         error = -EMFILE;
 716         write_lock(&files->file_lock);
 717
 718 repeat:
 719         fd = find_next_zero_bit(files->open_fds,
 720                                 current->files->max_fdset,
 721                                 files->next_fd);
 722
 723         /*
 724          * N.B. For clone tasks sharing a files structure, this test
 725          * will limit the total number of files that can be opened.
 726          */
 727         if (fd >= current->rlim[RLIMIT_NOFILE].rlim_cur)
 728                 goto out;
 729
 730         /* Do we need to expand the fdset array? */
 731         if (fd >= current->files->max_fdset) {
 732                 error = expand_fdset(files, fd);
 733                 if (!error) {
 734                         error = -EMFILE;
 735                         goto repeat;
 736                 }
 737                 goto out;
 738         }
 739
 740         /*
 741          * Check whether we need to expand the fd array.
 742          */
 743         if (fd >= files->max_fds) {
 744                 error = expand_fd_array(files, fd);
 745                 if (!error) {
 746                         error = -EMFILE;
 747                         goto repeat;
 748                 }
 749                 goto out;
 750         }
 751
 752         FD_SET(fd, files->open_fds);
 753         FD_CLR(fd, files->close_on_exec);
 754         files->next_fd = fd + 1;
 755 #if 1
 756         /* Sanity check */
 757         if (files->fd[fd] != NULL) {
 758                 printk("get_unused_fd: slot %d not NULL!\n", fd);
 759                 files->fd[fd] = NULL;
 760         }
 761 #endif
 762         error = fd;
 763
 764 out:
 765         write_unlock(&files->file_lock);
 766         return error;
 767 }
 768
 769 inline void put_unused_fd(unsigned int fd)
 770 {
 771         write_lock(&current->files->file_lock);
 772         FD_CLR(fd, current->files->open_fds);
 773         if (fd < current->files->next_fd)
 774                 current->files->next_fd = fd;
 775         write_unlock(&current->files->file_lock);
 776 }
 777
 778 asmlinkage long sys_open(const char * filename, int flags, int mode)
 779 {
 780         char * tmp;
 781         int fd, error;
 782
 783 #if BITS_PER_LONG != 32
 784         flags |= O_LARGEFILE;
 785 #endif
 786         tmp = getname(filename);
 787         fd = PTR_ERR(tmp);
 788         if (!IS_ERR(tmp)) {
 789                 fd = get_unused_fd();
 790                 if (fd >= 0) {
 791                         struct file * f;
 792                         lock_kernel();
 793                         f = filp_open(tmp, flags, mode);
 794                         unlock_kernel();
 795                         error = PTR_ERR(f);
 796                         if (IS_ERR(f))
 797                                 goto out_error;
 798                         fd_install(fd, f);
 799                 }
 800 out:
 801                 putname(tmp);
 802         }
 803         return fd;
 804
 805 out_error:
 806         put_unused_fd(fd);
 807         fd = error;
 808         goto out;
 809 }
 810
 811 #ifndef __alpha__
 812
 813 /*
 814  * For backward compatibility?  Maybe this should be moved
 815  * into arch/i386 instead?
 816  */
 817 asmlinkage long sys_creat(const char * pathname, int mode)
 818 {
 819         return sys_open(pathname, O_CREAT | O_WRONLY | O_TRUNC, mode);
 820 }
 821
 822 #endif
 823
 824 /*
 825  * "id" is the POSIX thread ID. We use the
 826  * files pointer for this..
 827  */
 828 int filp_close(struct file *filp, fl_owner_t id)
 829 {
 830         int retval;
 831         struct dentry *dentry = filp->f_dentry;
 832
 833         if (!file_count(filp)) {
 834                 printk("VFS: Close: file count is 0\n");
 835                 return 0;
 836         }
 837         retval = 0;
 838         if (filp->f_op && filp->f_op->flush)
 839                 retval = filp->f_op->flush(filp);
 840         if (dentry->d_inode)
 841                 locks_remove_posix(filp, id);
 842         fput(filp);
 843         return retval;
 844 }
 845
 846 /*
 847  * Careful here! We test whether the file pointer is NULL before
 848  * releasing the fd. This ensures that one clone task can't release
 849  * an fd while another clone is opening it.
 850  *
 851  * The "release" argument tells us whether or not to mark the fd as free
 852  * or not in the open-files bitmap.  dup2 uses this to retain the fd
 853  * without races.
 854  */
 855 int do_close(unsigned int fd, int release)
 856 {
 857         int error;
 858         struct file * filp;
 859         struct files_struct * files = current->files;
 860
 861         error = -EBADF;
 862         write_lock(&files->file_lock);
 863         filp = frip(fd);
 864         if (!filp)
 865                 goto out_unlock;
 866         FD_CLR(fd, files->close_on_exec);
 867         write_unlock(&files->file_lock);
 868         if (release)
 869                 put_unused_fd(fd);
 870         lock_kernel();
 871         error = filp_close(filp, files);
 872         unlock_kernel();
 873 out:
 874         return error;
 875 out_unlock:
 876         write_unlock(&files->file_lock);
 877         goto out;
 878 }
 879
 880 asmlinkage long sys_close(unsigned int fd)
 881 {
 882         return do_close(fd, 1);
 883 }
 884
 885 /*
 886  * This routine simulates a hangup on the tty, to arrange that users
 887  * are given clean terminals at login time.
 888  */
 889 asmlinkage long sys_vhangup(void)
 890 {
 891         if (capable(CAP_SYS_TTY_CONFIG)) {
 892                 tty_vhangup(current->tty);
 893                 return 0;
 894         }
 895         return -EPERM;
 896 }