fs/stat.c

   1 /*
   2  *  linux/fs/stat.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 #include <linux/module.h>
   8 #include <linux/mm.h>
   9 #include <linux/errno.h>
  10 #include <linux/file.h>
  11 #include <linux/highuid.h>
  12 #include <linux/fs.h>
  13 #include <linux/namei.h>
  14 #include <linux/security.h>
  15 #include <linux/syscalls.h>
  16 #include <linux/pagemap.h>
  17
  18 #include <asm/uaccess.h>
  19 #include <asm/unistd.h>
  20
  21 void generic_fillattr(struct inode *inode, struct kstat *stat)
  22 {
  23         stat->dev = inode->i_sb->s_dev;
  24         stat->ino = inode->i_ino;
  25         stat->mode = inode->i_mode;
  26         stat->nlink = inode->i_nlink;
  27         stat->uid = inode->i_uid;
  28         stat->gid = inode->i_gid;
  29         stat->rdev = inode->i_rdev;
  30         stat->size = i_size_read(inode);
  31         stat->atime = inode->i_atime;
  32         stat->mtime = inode->i_mtime;
  33         stat->ctime = inode->i_ctime;
  34         stat->blksize = (1 << inode->i_blkbits);
  35         stat->blocks = inode->i_blocks;
  36 }
  37
  38 EXPORT_SYMBOL(generic_fillattr);
  39
  40 int vfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
  41 {
  42         struct inode *inode = dentry->d_inode;
  43         int retval;
  44
  45         retval = security_inode_getattr(mnt, dentry);
  46         if (retval)
  47                 return retval;
  48
  49         if (inode->i_op->getattr)
  50                 return inode->i_op->getattr(mnt, dentry, stat);
  51
  52         generic_fillattr(inode, stat);
  53         return 0;
  54 }
  55
  56 EXPORT_SYMBOL(vfs_getattr);
  57
  58 int vfs_fstat(unsigned int fd, struct kstat *stat)
  59 {
  60         struct file *f = fget(fd);
  61         int error = -EBADF;
  62
  63         if (f) {
  64                 error = vfs_getattr(f->f_path.mnt, f->f_path.dentry, stat);
  65                 fput(f);
  66         }
  67         return error;
  68 }
  69 EXPORT_SYMBOL(vfs_fstat);
  70
  71 int vfs_fstatat(int dfd, const char __user *filename, struct kstat *stat,
  72                 int flag)
  73 {
  74         struct path path;
  75         int error = -EINVAL;
  76         int lookup_flags = 0;
  77
  78         if ((flag & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
  79                       AT_EMPTY_PATH)) != 0)
  80                 goto out;
  81
  82         if (!(flag & AT_SYMLINK_NOFOLLOW))
  83                 lookup_flags |= LOOKUP_FOLLOW;
  84         if (flag & AT_NO_AUTOMOUNT)
  85                 lookup_flags |= LOOKUP_NO_AUTOMOUNT;
  86         if (flag & AT_EMPTY_PATH)
  87                 lookup_flags |= LOOKUP_EMPTY;
  88
  89         error = user_path_at(dfd, filename, lookup_flags, &path);
  90         if (error)
  91                 goto out;
  92
  93         error = vfs_getattr(path.mnt, path.dentry, stat);
  94         path_put(&path);
  95 out:
  96         return error;
  97 }
  98 EXPORT_SYMBOL(vfs_fstatat);
  99
 100 int vfs_stat(const char __user *name, struct kstat *stat)
 101 {
 102         return vfs_fstatat(AT_FDCWD, name, stat, 0);
 103 }
 104 EXPORT_SYMBOL(vfs_stat);
 105
 106 int vfs_lstat(const char __user *name, struct kstat *stat)
 107 {
 108         return vfs_fstatat(AT_FDCWD, name, stat, AT_SYMLINK_NOFOLLOW);
 109 }
 110 EXPORT_SYMBOL(vfs_lstat);
 111
 112
 113 #ifdef __ARCH_WANT_OLD_STAT
 114
 115 /*
 116  * For backward compatibility?  Maybe this should be moved
 117  * into arch/i386 instead?
 118  */
 119 static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * statbuf)
 120 {
 121         static int warncount = 5;
 122         struct __old_kernel_stat tmp;
 123
 124         if (warncount > 0) {
 125                 warncount--;
 126                 printk(KERN_WARNING "VFS: Warning: %s using old stat() call. Recompile your binary.\n",
 127                         current->comm);
 128         } else if (warncount < 0) {
 129                 /* it's laughable, but... */
 130                 warncount = 0;
 131         }
 132
 133         memset(&tmp, 0, sizeof(struct __old_kernel_stat));
 134         tmp.st_dev = old_encode_dev(stat->dev);
 135         tmp.st_ino = stat->ino;
 136         if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
 137                 return -EOVERFLOW;
 138         tmp.st_mode = stat->mode;
 139         tmp.st_nlink = stat->nlink;
 140         if (tmp.st_nlink != stat->nlink)
 141                 return -EOVERFLOW;
 142         SET_UID(tmp.st_uid, stat->uid);
 143         SET_GID(tmp.st_gid, stat->gid);
 144         tmp.st_rdev = old_encode_dev(stat->rdev);
 145 #if BITS_PER_LONG == 32
 146         if (stat->size > MAX_NON_LFS)
 147                 return -EOVERFLOW;
 148 #endif
 149         tmp.st_size = stat->size;
 150         tmp.st_atime = stat->atime.tv_sec;
 151         tmp.st_mtime = stat->mtime.tv_sec;
 152         tmp.st_ctime = stat->ctime.tv_sec;
 153         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
 154 }
 155
 156 SYSCALL_DEFINE2(stat, const char __user *, filename,
 157                 struct __old_kernel_stat __user *, statbuf)
 158 {
 159         struct kstat stat;
 160         int error;
 161
 162         error = vfs_stat(filename, &stat);
 163         if (error)
 164                 return error;
 165
 166         return cp_old_stat(&stat, statbuf);
 167 }
 168
 169 SYSCALL_DEFINE2(lstat, const char __user *, filename,
 170                 struct __old_kernel_stat __user *, statbuf)
 171 {
 172         struct kstat stat;
 173         int error;
 174
 175         error = vfs_lstat(filename, &stat);
 176         if (error)
 177                 return error;
 178
 179         return cp_old_stat(&stat, statbuf);
 180 }
 181
 182 SYSCALL_DEFINE2(fstat, unsigned int, fd, struct __old_kernel_stat __user *, statbuf)
 183 {
 184         struct kstat stat;
 185         int error = vfs_fstat(fd, &stat);
 186
 187         if (!error)
 188                 error = cp_old_stat(&stat, statbuf);
 189
 190         return error;
 191 }
 192
 193 #endif /* __ARCH_WANT_OLD_STAT */
 194
 195 static int cp_new_stat(struct kstat *stat, struct stat __user *statbuf)
 196 {
 197         struct stat tmp;
 198
 199 #if BITS_PER_LONG == 32
 200         if (!old_valid_dev(stat->dev) || !old_valid_dev(stat->rdev))
 201                 return -EOVERFLOW;
 202 #else
 203         if (!new_valid_dev(stat->dev) || !new_valid_dev(stat->rdev))
 204                 return -EOVERFLOW;
 205 #endif
 206
 207         memset(&tmp, 0, sizeof(tmp));
 208 #if BITS_PER_LONG == 32
 209         tmp.st_dev = old_encode_dev(stat->dev);
 210 #else
 211         tmp.st_dev = new_encode_dev(stat->dev);
 212 #endif
 213         tmp.st_ino = stat->ino;
 214         if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
 215                 return -EOVERFLOW;
 216         tmp.st_mode = stat->mode;
 217         tmp.st_nlink = stat->nlink;
 218         if (tmp.st_nlink != stat->nlink)
 219                 return -EOVERFLOW;
 220         SET_UID(tmp.st_uid, stat->uid);
 221         SET_GID(tmp.st_gid, stat->gid);
 222 #if BITS_PER_LONG == 32
 223         tmp.st_rdev = old_encode_dev(stat->rdev);
 224 #else
 225         tmp.st_rdev = new_encode_dev(stat->rdev);
 226 #endif
 227 #if BITS_PER_LONG == 32
 228         if (stat->size > MAX_NON_LFS)
 229                 return -EOVERFLOW;
 230 #endif
 231         tmp.st_size = stat->size;
 232         tmp.st_atime = stat->atime.tv_sec;
 233         tmp.st_mtime = stat->mtime.tv_sec;
 234         tmp.st_ctime = stat->ctime.tv_sec;
 235 #ifdef STAT_HAVE_NSEC
 236         tmp.st_atime_nsec = stat->atime.tv_nsec;
 237         tmp.st_mtime_nsec = stat->mtime.tv_nsec;
 238         tmp.st_ctime_nsec = stat->ctime.tv_nsec;
 239 #endif
 240         tmp.st_blocks = stat->blocks;
 241         tmp.st_blksize = stat->blksize;
 242         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
 243 }
 244
 245 SYSCALL_DEFINE2(newstat, const char __user *, filename,
 246                 struct stat __user *, statbuf)
 247 {
 248         struct kstat stat;
 249         int error = vfs_stat(filename, &stat);
 250
 251         if (error)
 252                 return error;
 253         return cp_new_stat(&stat, statbuf);
 254 }
 255
 256 SYSCALL_DEFINE2(newlstat, const char __user *, filename,
 257                 struct stat __user *, statbuf)
 258 {
 259         struct kstat stat;
 260         int error;
 261
 262         error = vfs_lstat(filename, &stat);
 263         if (error)
 264                 return error;
 265
 266         return cp_new_stat(&stat, statbuf);
 267 }
 268
 269 #if !defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_SYS_NEWFSTATAT)
 270 SYSCALL_DEFINE4(newfstatat, int, dfd, const char __user *, filename,
 271                 struct stat __user *, statbuf, int, flag)
 272 {
 273         struct kstat stat;
 274         int error;
 275
 276         error = vfs_fstatat(dfd, filename, &stat, flag);
 277         if (error)
 278                 return error;
 279         return cp_new_stat(&stat, statbuf);
 280 }
 281 #endif
 282
 283 SYSCALL_DEFINE2(newfstat, unsigned int, fd, struct stat __user *, statbuf)
 284 {
 285         struct kstat stat;
 286         int error = vfs_fstat(fd, &stat);
 287
 288         if (!error)
 289                 error = cp_new_stat(&stat, statbuf);
 290
 291         return error;
 292 }
 293
 294 SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
 295                 char __user *, buf, int, bufsiz)
 296 {
 297         struct path path;
 298         int error;
 299         int empty = 0;
 300
 301         if (bufsiz <= 0)
 302                 return -EINVAL;
 303
 304         error = user_path_at_empty(dfd, pathname, LOOKUP_EMPTY, &path, &empty);
 305         if (!error) {
 306                 struct inode *inode = path.dentry->d_inode;
 307
 308                 error = (empty) ? -ENOENT : -EINVAL;
 309                 if (inode->i_op->readlink) {
 310                         error = security_inode_readlink(path.dentry);
 311                         if (!error) {
 312                                 touch_atime(path.mnt, path.dentry);
 313                                 error = inode->i_op->readlink(path.dentry,
 314                                                               buf, bufsiz);
 315                         }
 316                 }
 317                 path_put(&path);
 318         }
 319         return error;
 320 }
 321
 322 SYSCALL_DEFINE3(readlink, const char __user *, path, char __user *, buf,
 323                 int, bufsiz)
 324 {
 325         return sys_readlinkat(AT_FDCWD, path, buf, bufsiz);
 326 }
 327
 328
 329 /* ---------- LFS-64 ----------- */
 330 #ifdef __ARCH_WANT_STAT64
 331
 332 static long cp_new_stat64(struct kstat *stat, struct stat64 __user *statbuf)
 333 {
 334         struct stat64 tmp;
 335
 336         memset(&tmp, 0, sizeof(struct stat64));
 337 #ifdef CONFIG_MIPS
 338         /* mips has weird padding, so we don't get 64 bits there */
 339         if (!new_valid_dev(stat->dev) || !new_valid_dev(stat->rdev))
 340                 return -EOVERFLOW;
 341         tmp.st_dev = new_encode_dev(stat->dev);
 342         tmp.st_rdev = new_encode_dev(stat->rdev);
 343 #else
 344         tmp.st_dev = huge_encode_dev(stat->dev);
 345         tmp.st_rdev = huge_encode_dev(stat->rdev);
 346 #endif
 347         tmp.st_ino = stat->ino;
 348         if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
 349                 return -EOVERFLOW;
 350 #ifdef STAT64_HAS_BROKEN_ST_INO
 351         tmp.__st_ino = stat->ino;
 352 #endif
 353         tmp.st_mode = stat->mode;
 354         tmp.st_nlink = stat->nlink;
 355         tmp.st_uid = stat->uid;
 356         tmp.st_gid = stat->gid;
 357         tmp.st_atime = stat->atime.tv_sec;
 358         tmp.st_atime_nsec = stat->atime.tv_nsec;
 359         tmp.st_mtime = stat->mtime.tv_sec;
 360         tmp.st_mtime_nsec = stat->mtime.tv_nsec;
 361         tmp.st_ctime = stat->ctime.tv_sec;
 362         tmp.st_ctime_nsec = stat->ctime.tv_nsec;
 363         tmp.st_size = stat->size;
 364         tmp.st_blocks = stat->blocks;
 365         tmp.st_blksize = stat->blksize;
 366         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
 367 }
 368
 369 SYSCALL_DEFINE2(stat64, const char __user *, filename,
 370                 struct stat64 __user *, statbuf)
 371 {
 372         struct kstat stat;
 373         int error = vfs_stat(filename, &stat);
 374
 375         if (!error)
 376                 error = cp_new_stat64(&stat, statbuf);
 377
 378         return error;
 379 }
 380
 381 SYSCALL_DEFINE2(lstat64, const char __user *, filename,
 382                 struct stat64 __user *, statbuf)
 383 {
 384         struct kstat stat;
 385         int error = vfs_lstat(filename, &stat);
 386
 387         if (!error)
 388                 error = cp_new_stat64(&stat, statbuf);
 389
 390         return error;
 391 }
 392
 393 SYSCALL_DEFINE2(fstat64, unsigned long, fd, struct stat64 __user *, statbuf)
 394 {
 395         struct kstat stat;
 396         int error = vfs_fstat(fd, &stat);
 397
 398         if (!error)
 399                 error = cp_new_stat64(&stat, statbuf);
 400
 401         return error;
 402 }
 403
 404 SYSCALL_DEFINE4(fstatat64, int, dfd, const char __user *, filename,
 405                 struct stat64 __user *, statbuf, int, flag)
 406 {
 407         struct kstat stat;
 408         int error;
 409
 410         error = vfs_fstatat(dfd, filename, &stat, flag);
 411         if (error)
 412                 return error;
 413         return cp_new_stat64(&stat, statbuf);
 414 }
 415 #endif /* __ARCH_WANT_STAT64 */
 416
 417 /* Caller is here responsible for sufficient locking (ie. inode->i_lock) */
 418 void __inode_add_bytes(struct inode *inode, loff_t bytes)
 419 {
 420         inode->i_blocks += bytes >> 9;
 421         bytes &= 511;
 422         inode->i_bytes += bytes;
 423         if (inode->i_bytes >= 512) {
 424                 inode->i_blocks++;
 425                 inode->i_bytes -= 512;
 426         }
 427 }
 428
 429 void inode_add_bytes(struct inode *inode, loff_t bytes)
 430 {
 431         spin_lock(&inode->i_lock);
 432         __inode_add_bytes(inode, bytes);
 433         spin_unlock(&inode->i_lock);
 434 }
 435
 436 EXPORT_SYMBOL(inode_add_bytes);
 437
 438 void inode_sub_bytes(struct inode *inode, loff_t bytes)
 439 {
 440         spin_lock(&inode->i_lock);
 441         inode->i_blocks -= bytes >> 9;
 442         bytes &= 511;
 443         if (inode->i_bytes < bytes) {
 444                 inode->i_blocks--;
 445                 inode->i_bytes += 512;
 446         }
 447         inode->i_bytes -= bytes;
 448         spin_unlock(&inode->i_lock);
 449 }
 450
 451 EXPORT_SYMBOL(inode_sub_bytes);
 452
 453 loff_t inode_get_bytes(struct inode *inode)
 454 {
 455         loff_t ret;
 456
 457         spin_lock(&inode->i_lock);
 458         ret = (((loff_t)inode->i_blocks) << 9) + inode->i_bytes;
 459         spin_unlock(&inode->i_lock);
 460         return ret;
 461 }
 462
 463 EXPORT_SYMBOL(inode_get_bytes);
 464
 465 void inode_set_bytes(struct inode *inode, loff_t bytes)
 466 {
 467         /* Caller is here responsible for sufficient locking
 468          * (ie. inode->i_lock) */
 469         inode->i_blocks = bytes >> 9;
 470         inode->i_bytes = bytes & 511;
 471 }
 472
 473 EXPORT_SYMBOL(inode_set_bytes);