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->atime = inode->i_atime;
  31         stat->mtime = inode->i_mtime;
  32         stat->ctime = inode->i_ctime;
  33         stat->size = i_size_read(inode);
  34         stat->blocks = inode->i_blocks;
  35         stat->blksize = (1 << inode->i_blkbits);
  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_stat_fd(int dfd, char __user *name, struct kstat *stat)
  59 {
  60         struct path path;
  61         int error;
  62
  63         error = user_path_at(dfd, name, LOOKUP_FOLLOW, &path);
  64         if (!error) {
  65                 error = vfs_getattr(path.mnt, path.dentry, stat);
  66                 path_put(&path);
  67         }
  68         return error;
  69 }
  70
  71 int vfs_stat(char __user *name, struct kstat *stat)
  72 {
  73         return vfs_stat_fd(AT_FDCWD, name, stat);
  74 }
  75
  76 EXPORT_SYMBOL(vfs_stat);
  77
  78 int vfs_lstat_fd(int dfd, char __user *name, struct kstat *stat)
  79 {
  80         struct path path;
  81         int error;
  82
  83         error = user_path_at(dfd, name, 0, &path);
  84         if (!error) {
  85                 error = vfs_getattr(path.mnt, path.dentry, stat);
  86                 path_put(&path);
  87         }
  88         return error;
  89 }
  90
  91 int vfs_lstat(char __user *name, struct kstat *stat)
  92 {
  93         return vfs_lstat_fd(AT_FDCWD, name, stat);
  94 }
  95
  96 EXPORT_SYMBOL(vfs_lstat);
  97
  98 int vfs_fstat(unsigned int fd, struct kstat *stat)
  99 {
 100         struct file *f = fget(fd);
 101         int error = -EBADF;
 102
 103         if (f) {
 104                 error = vfs_getattr(f->f_path.mnt, f->f_path.dentry, stat);
 105                 fput(f);
 106         }
 107         return error;
 108 }
 109
 110 EXPORT_SYMBOL(vfs_fstat);
 111
 112 #ifdef __ARCH_WANT_OLD_STAT
 113
 114 /*
 115  * For backward compatibility?  Maybe this should be moved
 116  * into arch/i386 instead?
 117  */
 118 static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * statbuf)
 119 {
 120         static int warncount = 5;
 121         struct __old_kernel_stat tmp;
 122
 123         if (warncount > 0) {
 124                 warncount--;
 125                 printk(KERN_WARNING "VFS: Warning: %s using old stat() call. Recompile your binary.\n",
 126                         current->comm);
 127         } else if (warncount < 0) {
 128                 /* it's laughable, but... */
 129                 warncount = 0;
 130         }
 131
 132         memset(&tmp, 0, sizeof(struct __old_kernel_stat));
 133         tmp.st_dev = old_encode_dev(stat->dev);
 134         tmp.st_ino = stat->ino;
 135         if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
 136                 return -EOVERFLOW;
 137         tmp.st_mode = stat->mode;
 138         tmp.st_nlink = stat->nlink;
 139         if (tmp.st_nlink != stat->nlink)
 140                 return -EOVERFLOW;
 141         SET_UID(tmp.st_uid, stat->uid);
 142         SET_GID(tmp.st_gid, stat->gid);
 143         tmp.st_rdev = old_encode_dev(stat->rdev);
 144 #if BITS_PER_LONG == 32
 145         if (stat->size > MAX_NON_LFS)
 146                 return -EOVERFLOW;
 147 #endif
 148         tmp.st_size = stat->size;
 149         tmp.st_atime = stat->atime.tv_sec;
 150         tmp.st_mtime = stat->mtime.tv_sec;
 151         tmp.st_ctime = stat->ctime.tv_sec;
 152         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
 153 }
 154
 155 SYSCALL_DEFINE2(stat, char __user *, filename, struct __old_kernel_stat __user *, statbuf)
 156 {
 157         struct kstat stat;
 158         int error = vfs_stat_fd(AT_FDCWD, filename, &stat);
 159
 160         if (!error)
 161                 error = cp_old_stat(&stat, statbuf);
 162
 163         return error;
 164 }
 165
 166 SYSCALL_DEFINE2(lstat, char __user *, filename, struct __old_kernel_stat __user *, statbuf)
 167 {
 168         struct kstat stat;
 169         int error = vfs_lstat_fd(AT_FDCWD, filename, &stat);
 170
 171         if (!error)
 172                 error = cp_old_stat(&stat, statbuf);
 173
 174         return error;
 175 }
 176
 177 SYSCALL_DEFINE2(fstat, unsigned int, fd, struct __old_kernel_stat __user *, statbuf)
 178 {
 179         struct kstat stat;
 180         int error = vfs_fstat(fd, &stat);
 181
 182         if (!error)
 183                 error = cp_old_stat(&stat, statbuf);
 184
 185         return error;
 186 }
 187
 188 #endif /* __ARCH_WANT_OLD_STAT */
 189
 190 static int cp_new_stat(struct kstat *stat, struct stat __user *statbuf)
 191 {
 192         struct stat tmp;
 193
 194 #if BITS_PER_LONG == 32
 195         if (!old_valid_dev(stat->dev) || !old_valid_dev(stat->rdev))
 196                 return -EOVERFLOW;
 197 #else
 198         if (!new_valid_dev(stat->dev) || !new_valid_dev(stat->rdev))
 199                 return -EOVERFLOW;
 200 #endif
 201
 202         memset(&tmp, 0, sizeof(tmp));
 203 #if BITS_PER_LONG == 32
 204         tmp.st_dev = old_encode_dev(stat->dev);
 205 #else
 206         tmp.st_dev = new_encode_dev(stat->dev);
 207 #endif
 208         tmp.st_ino = stat->ino;
 209         if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
 210                 return -EOVERFLOW;
 211         tmp.st_mode = stat->mode;
 212         tmp.st_nlink = stat->nlink;
 213         if (tmp.st_nlink != stat->nlink)
 214                 return -EOVERFLOW;
 215         SET_UID(tmp.st_uid, stat->uid);
 216         SET_GID(tmp.st_gid, stat->gid);
 217 #if BITS_PER_LONG == 32
 218         tmp.st_rdev = old_encode_dev(stat->rdev);
 219 #else
 220         tmp.st_rdev = new_encode_dev(stat->rdev);
 221 #endif
 222 #if BITS_PER_LONG == 32
 223         if (stat->size > MAX_NON_LFS)
 224                 return -EOVERFLOW;
 225 #endif
 226         tmp.st_size = stat->size;
 227         tmp.st_atime = stat->atime.tv_sec;
 228         tmp.st_mtime = stat->mtime.tv_sec;
 229         tmp.st_ctime = stat->ctime.tv_sec;
 230 #ifdef STAT_HAVE_NSEC
 231         tmp.st_atime_nsec = stat->atime.tv_nsec;
 232         tmp.st_mtime_nsec = stat->mtime.tv_nsec;
 233         tmp.st_ctime_nsec = stat->ctime.tv_nsec;
 234 #endif
 235         tmp.st_blocks = stat->blocks;
 236         tmp.st_blksize = stat->blksize;
 237         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
 238 }
 239
 240 SYSCALL_DEFINE2(newstat, char __user *, filename, struct stat __user *, statbuf)
 241 {
 242         struct kstat stat;
 243         int error = vfs_stat_fd(AT_FDCWD, filename, &stat);
 244
 245         if (!error)
 246                 error = cp_new_stat(&stat, statbuf);
 247
 248         return error;
 249 }
 250
 251 SYSCALL_DEFINE2(newlstat, char __user *, filename, struct stat __user *, statbuf)
 252 {
 253         struct kstat stat;
 254         int error = vfs_lstat_fd(AT_FDCWD, filename, &stat);
 255
 256         if (!error)
 257                 error = cp_new_stat(&stat, statbuf);
 258
 259         return error;
 260 }
 261
 262 #if !defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_SYS_NEWFSTATAT)
 263 SYSCALL_DEFINE4(newfstatat, int, dfd, char __user *, filename,
 264                 struct stat __user *, statbuf, int, flag)
 265 {
 266         struct kstat stat;
 267         int error = -EINVAL;
 268
 269         if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)
 270                 goto out;
 271
 272         if (flag & AT_SYMLINK_NOFOLLOW)
 273                 error = vfs_lstat_fd(dfd, filename, &stat);
 274         else
 275                 error = vfs_stat_fd(dfd, filename, &stat);
 276
 277         if (!error)
 278                 error = cp_new_stat(&stat, statbuf);
 279
 280 out:
 281         return error;
 282 }
 283 #endif
 284
 285 SYSCALL_DEFINE2(newfstat, unsigned int, fd, struct stat __user *, statbuf)
 286 {
 287         struct kstat stat;
 288         int error = vfs_fstat(fd, &stat);
 289
 290         if (!error)
 291                 error = cp_new_stat(&stat, statbuf);
 292
 293         return error;
 294 }
 295
 296 SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
 297                 char __user *, buf, int, bufsiz)
 298 {
 299         struct path path;
 300         int error;
 301
 302         if (bufsiz <= 0)
 303                 return -EINVAL;
 304
 305         error = user_path_at(dfd, pathname, 0, &path);
 306         if (!error) {
 307                 struct inode *inode = path.dentry->d_inode;
 308
 309                 error = -EINVAL;
 310                 if (inode->i_op && inode->i_op->readlink) {
 311                         error = security_inode_readlink(path.dentry);
 312                         if (!error) {
 313                                 touch_atime(path.mnt, path.dentry);
 314                                 error = inode->i_op->readlink(path.dentry,
 315                                                               buf, bufsiz);
 316                         }
 317                 }
 318                 path_put(&path);
 319         }
 320         return error;
 321 }
 322
 323 SYSCALL_DEFINE3(readlink, const char __user *, path, char __user *, buf,
 324                 int, bufsiz)
 325 {
 326         return sys_readlinkat(AT_FDCWD, path, buf, bufsiz);
 327 }
 328
 329
 330 /* ---------- LFS-64 ----------- */
 331 #ifdef __ARCH_WANT_STAT64
 332
 333 static long cp_new_stat64(struct kstat *stat, struct stat64 __user *statbuf)
 334 {
 335         struct stat64 tmp;
 336
 337         memset(&tmp, 0, sizeof(struct stat64));
 338 #ifdef CONFIG_MIPS
 339         /* mips has weird padding, so we don't get 64 bits there */
 340         if (!new_valid_dev(stat->dev) || !new_valid_dev(stat->rdev))
 341                 return -EOVERFLOW;
 342         tmp.st_dev = new_encode_dev(stat->dev);
 343         tmp.st_rdev = new_encode_dev(stat->rdev);
 344 #else
 345         tmp.st_dev = huge_encode_dev(stat->dev);
 346         tmp.st_rdev = huge_encode_dev(stat->rdev);
 347 #endif
 348         tmp.st_ino = stat->ino;
 349         if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
 350                 return -EOVERFLOW;
 351 #ifdef STAT64_HAS_BROKEN_ST_INO
 352         tmp.__st_ino = stat->ino;
 353 #endif
 354         tmp.st_mode = stat->mode;
 355         tmp.st_nlink = stat->nlink;
 356         tmp.st_uid = stat->uid;
 357         tmp.st_gid = stat->gid;
 358         tmp.st_atime = stat->atime.tv_sec;
 359         tmp.st_atime_nsec = stat->atime.tv_nsec;
 360         tmp.st_mtime = stat->mtime.tv_sec;
 361         tmp.st_mtime_nsec = stat->mtime.tv_nsec;
 362         tmp.st_ctime = stat->ctime.tv_sec;
 363         tmp.st_ctime_nsec = stat->ctime.tv_nsec;
 364         tmp.st_size = stat->size;
 365         tmp.st_blocks = stat->blocks;
 366         tmp.st_blksize = stat->blksize;
 367         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
 368 }
 369
 370 SYSCALL_DEFINE2(stat64, char __user *, filename, 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, char __user *, filename, struct stat64 __user *, statbuf)
 382 {
 383         struct kstat stat;
 384         int error = vfs_lstat(filename, &stat);
 385
 386         if (!error)
 387                 error = cp_new_stat64(&stat, statbuf);
 388
 389         return error;
 390 }
 391
 392 SYSCALL_DEFINE2(fstat64, unsigned long, fd, struct stat64 __user *, statbuf)
 393 {
 394         struct kstat stat;
 395         int error = vfs_fstat(fd, &stat);
 396
 397         if (!error)
 398                 error = cp_new_stat64(&stat, statbuf);
 399
 400         return error;
 401 }
 402
 403 SYSCALL_DEFINE4(fstatat64, int, dfd, char __user *, filename,
 404                 struct stat64 __user *, statbuf, int, flag)
 405 {
 406         struct kstat stat;
 407         int error = -EINVAL;
 408
 409         if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)
 410                 goto out;
 411
 412         if (flag & AT_SYMLINK_NOFOLLOW)
 413                 error = vfs_lstat_fd(dfd, filename, &stat);
 414         else
 415                 error = vfs_stat_fd(dfd, filename, &stat);
 416
 417         if (!error)
 418                 error = cp_new_stat64(&stat, statbuf);
 419
 420 out:
 421         return error;
 422 }
 423 #endif /* __ARCH_WANT_STAT64 */
 424
 425 void inode_add_bytes(struct inode *inode, loff_t bytes)
 426 {
 427         spin_lock(&inode->i_lock);
 428         inode->i_blocks += bytes >> 9;
 429         bytes &= 511;
 430         inode->i_bytes += bytes;
 431         if (inode->i_bytes >= 512) {
 432                 inode->i_blocks++;
 433                 inode->i_bytes -= 512;
 434         }
 435         spin_unlock(&inode->i_lock);
 436 }
 437
 438 EXPORT_SYMBOL(inode_add_bytes);
 439
 440 void inode_sub_bytes(struct inode *inode, loff_t bytes)
 441 {
 442         spin_lock(&inode->i_lock);
 443         inode->i_blocks -= bytes >> 9;
 444         bytes &= 511;
 445         if (inode->i_bytes < bytes) {
 446                 inode->i_blocks--;
 447                 inode->i_bytes += 512;
 448         }
 449         inode->i_bytes -= bytes;
 450         spin_unlock(&inode->i_lock);
 451 }
 452
 453 EXPORT_SYMBOL(inode_sub_bytes);
 454
 455 loff_t inode_get_bytes(struct inode *inode)
 456 {
 457         loff_t ret;
 458
 459         spin_lock(&inode->i_lock);
 460         ret = (((loff_t)inode->i_blocks) << 9) + inode->i_bytes;
 461         spin_unlock(&inode->i_lock);
 462         return ret;
 463 }
 464
 465 EXPORT_SYMBOL(inode_get_bytes);
 466
 467 void inode_set_bytes(struct inode *inode, loff_t bytes)
 468 {
 469         /* Caller is here responsible for sufficient locking
 470          * (ie. inode->i_lock) */
 471         inode->i_blocks = bytes >> 9;
 472         inode->i_bytes = bytes & 511;
 473 }
 474
 475 EXPORT_SYMBOL(inode_set_bytes);