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_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) != 0)
  79                 goto out;
  80
  81         if (!(flag & AT_SYMLINK_NOFOLLOW))
  82                 lookup_flags |= LOOKUP_FOLLOW;
  83
  84         error = user_path_at(dfd, filename, lookup_flags, &path);
  85         if (error)
  86                 goto out;
  87
  88         error = vfs_getattr(path.mnt, path.dentry, stat);
  89         path_put(&path);
  90 out:
  91         return error;
  92 }
  93 EXPORT_SYMBOL(vfs_fstatat);
  94
  95 int vfs_stat(const char __user *name, struct kstat *stat)
  96 {
  97         return vfs_fstatat(AT_FDCWD, name, stat, 0);
  98 }
  99 EXPORT_SYMBOL(vfs_stat);
 100
 101 int vfs_lstat(const char __user *name, struct kstat *stat)
 102 {
 103         return vfs_fstatat(AT_FDCWD, name, stat, AT_SYMLINK_NOFOLLOW);
 104 }
 105 EXPORT_SYMBOL(vfs_lstat);
 106
 107
 108 #ifdef __ARCH_WANT_OLD_STAT
 109
 110 /*
 111  * For backward compatibility?  Maybe this should be moved
 112  * into arch/i386 instead?
 113  */
 114 static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * statbuf)
 115 {
 116         static int warncount = 5;
 117         struct __old_kernel_stat tmp;
 118
 119         if (warncount > 0) {
 120                 warncount--;
 121                 printk(KERN_WARNING "VFS: Warning: %s using old stat() call. Recompile your binary.\n",
 122                         current->comm);
 123         } else if (warncount < 0) {
 124                 /* it's laughable, but... */
 125                 warncount = 0;
 126         }
 127
 128         memset(&tmp, 0, sizeof(struct __old_kernel_stat));
 129         tmp.st_dev = old_encode_dev(stat->dev);
 130         tmp.st_ino = stat->ino;
 131         if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
 132                 return -EOVERFLOW;
 133         tmp.st_mode = stat->mode;
 134         tmp.st_nlink = stat->nlink;
 135         if (tmp.st_nlink != stat->nlink)
 136                 return -EOVERFLOW;
 137         SET_UID(tmp.st_uid, stat->uid);
 138         SET_GID(tmp.st_gid, stat->gid);
 139         tmp.st_rdev = old_encode_dev(stat->rdev);
 140 #if BITS_PER_LONG == 32
 141         if (stat->size > MAX_NON_LFS)
 142                 return -EOVERFLOW;
 143 #endif
 144         tmp.st_size = stat->size;
 145         tmp.st_atime = stat->atime.tv_sec;
 146         tmp.st_mtime = stat->mtime.tv_sec;
 147         tmp.st_ctime = stat->ctime.tv_sec;
 148         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
 149 }
 150
 151 SYSCALL_DEFINE2(stat, const char __user *, filename,
 152                 struct __old_kernel_stat __user *, statbuf)
 153 {
 154         struct kstat stat;
 155         int error;
 156
 157         error = vfs_stat(filename, &stat);
 158         if (error)
 159                 return error;
 160
 161         return cp_old_stat(&stat, statbuf);
 162 }
 163
 164 SYSCALL_DEFINE2(lstat, const char __user *, filename,
 165                 struct __old_kernel_stat __user *, statbuf)
 166 {
 167         struct kstat stat;
 168         int error;
 169
 170         error = vfs_lstat(filename, &stat);
 171         if (error)
 172                 return error;
 173
 174         return cp_old_stat(&stat, statbuf);
 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, const char __user *, filename,
 241                 struct stat __user *, statbuf)
 242 {
 243         struct kstat stat;
 244         int error = vfs_stat(filename, &stat);
 245
 246         if (error)
 247                 return error;
 248         return cp_new_stat(&stat, statbuf);
 249 }
 250
 251 SYSCALL_DEFINE2(newlstat, const char __user *, filename,
 252                 struct stat __user *, statbuf)
 253 {
 254         struct kstat stat;
 255         int error;
 256
 257         error = vfs_lstat(filename, &stat);
 258         if (error)
 259                 return error;
 260
 261         return cp_new_stat(&stat, statbuf);
 262 }
 263
 264 #if !defined(__ARCH_WANT_STAT64) || defined(__ARCH_WANT_SYS_NEWFSTATAT)
 265 SYSCALL_DEFINE4(newfstatat, int, dfd, const char __user *, filename,
 266                 struct stat __user *, statbuf, int, flag)
 267 {
 268         struct kstat stat;
 269         int error;
 270
 271         error = vfs_fstatat(dfd, filename, &stat, flag);
 272         if (error)
 273                 return error;
 274         return cp_new_stat(&stat, statbuf);
 275 }
 276 #endif
 277
 278 SYSCALL_DEFINE2(newfstat, unsigned int, fd, struct stat __user *, statbuf)
 279 {
 280         struct kstat stat;
 281         int error = vfs_fstat(fd, &stat);
 282
 283         if (!error)
 284                 error = cp_new_stat(&stat, statbuf);
 285
 286         return error;
 287 }
 288
 289 SYSCALL_DEFINE4(readlinkat, int, dfd, const char __user *, pathname,
 290                 char __user *, buf, int, bufsiz)
 291 {
 292         struct path path;
 293         int error;
 294
 295         if (bufsiz <= 0)
 296                 return -EINVAL;
 297
 298         error = user_path_at(dfd, pathname, 0, &path);
 299         if (!error) {
 300                 struct inode *inode = path.dentry->d_inode;
 301
 302                 error = -EINVAL;
 303                 if (inode->i_op->readlink) {
 304                         error = security_inode_readlink(path.dentry);
 305                         if (!error) {
 306                                 touch_atime(path.mnt, path.dentry);
 307                                 error = inode->i_op->readlink(path.dentry,
 308                                                               buf, bufsiz);
 309                         }
 310                 }
 311                 path_put(&path);
 312         }
 313         return error;
 314 }
 315
 316 SYSCALL_DEFINE3(readlink, const char __user *, path, char __user *, buf,
 317                 int, bufsiz)
 318 {
 319         return sys_readlinkat(AT_FDCWD, path, buf, bufsiz);
 320 }
 321
 322
 323 /* ---------- LFS-64 ----------- */
 324 #ifdef __ARCH_WANT_STAT64
 325
 326 static long cp_new_stat64(struct kstat *stat, struct stat64 __user *statbuf)
 327 {
 328         struct stat64 tmp;
 329
 330         memset(&tmp, 0, sizeof(struct stat64));
 331 #ifdef CONFIG_MIPS
 332         /* mips has weird padding, so we don't get 64 bits there */
 333         if (!new_valid_dev(stat->dev) || !new_valid_dev(stat->rdev))
 334                 return -EOVERFLOW;
 335         tmp.st_dev = new_encode_dev(stat->dev);
 336         tmp.st_rdev = new_encode_dev(stat->rdev);
 337 #else
 338         tmp.st_dev = huge_encode_dev(stat->dev);
 339         tmp.st_rdev = huge_encode_dev(stat->rdev);
 340 #endif
 341         tmp.st_ino = stat->ino;
 342         if (sizeof(tmp.st_ino) < sizeof(stat->ino) && tmp.st_ino != stat->ino)
 343                 return -EOVERFLOW;
 344 #ifdef STAT64_HAS_BROKEN_ST_INO
 345         tmp.__st_ino = stat->ino;
 346 #endif
 347         tmp.st_mode = stat->mode;
 348         tmp.st_nlink = stat->nlink;
 349         tmp.st_uid = stat->uid;
 350         tmp.st_gid = stat->gid;
 351         tmp.st_atime = stat->atime.tv_sec;
 352         tmp.st_atime_nsec = stat->atime.tv_nsec;
 353         tmp.st_mtime = stat->mtime.tv_sec;
 354         tmp.st_mtime_nsec = stat->mtime.tv_nsec;
 355         tmp.st_ctime = stat->ctime.tv_sec;
 356         tmp.st_ctime_nsec = stat->ctime.tv_nsec;
 357         tmp.st_size = stat->size;
 358         tmp.st_blocks = stat->blocks;
 359         tmp.st_blksize = stat->blksize;
 360         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
 361 }
 362
 363 SYSCALL_DEFINE2(stat64, const char __user *, filename,
 364                 struct stat64 __user *, statbuf)
 365 {
 366         struct kstat stat;
 367         int error = vfs_stat(filename, &stat);
 368
 369         if (!error)
 370                 error = cp_new_stat64(&stat, statbuf);
 371
 372         return error;
 373 }
 374
 375 SYSCALL_DEFINE2(lstat64, const char __user *, filename,
 376                 struct stat64 __user *, statbuf)
 377 {
 378         struct kstat stat;
 379         int error = vfs_lstat(filename, &stat);
 380
 381         if (!error)
 382                 error = cp_new_stat64(&stat, statbuf);
 383
 384         return error;
 385 }
 386
 387 SYSCALL_DEFINE2(fstat64, unsigned long, fd, struct stat64 __user *, statbuf)
 388 {
 389         struct kstat stat;
 390         int error = vfs_fstat(fd, &stat);
 391
 392         if (!error)
 393                 error = cp_new_stat64(&stat, statbuf);
 394
 395         return error;
 396 }
 397
 398 SYSCALL_DEFINE4(fstatat64, int, dfd, const char __user *, filename,
 399                 struct stat64 __user *, statbuf, int, flag)
 400 {
 401         struct kstat stat;
 402         int error;
 403
 404         error = vfs_fstatat(dfd, filename, &stat, flag);
 405         if (error)
 406                 return error;
 407         return cp_new_stat64(&stat, statbuf);
 408 }
 409 #endif /* __ARCH_WANT_STAT64 */
 410
 411 /* Caller is here responsible for sufficient locking (ie. inode->i_lock) */
 412 void __inode_add_bytes(struct inode *inode, loff_t bytes)
 413 {
 414         inode->i_blocks += bytes >> 9;
 415         bytes &= 511;
 416         inode->i_bytes += bytes;
 417         if (inode->i_bytes >= 512) {
 418                 inode->i_blocks++;
 419                 inode->i_bytes -= 512;
 420         }
 421 }
 422
 423 void inode_add_bytes(struct inode *inode, loff_t bytes)
 424 {
 425         spin_lock(&inode->i_lock);
 426         __inode_add_bytes(inode, bytes);
 427         spin_unlock(&inode->i_lock);
 428 }
 429
 430 EXPORT_SYMBOL(inode_add_bytes);
 431
 432 void inode_sub_bytes(struct inode *inode, loff_t bytes)
 433 {
 434         spin_lock(&inode->i_lock);
 435         inode->i_blocks -= bytes >> 9;
 436         bytes &= 511;
 437         if (inode->i_bytes < bytes) {
 438                 inode->i_blocks--;
 439                 inode->i_bytes += 512;
 440         }
 441         inode->i_bytes -= bytes;
 442         spin_unlock(&inode->i_lock);
 443 }
 444
 445 EXPORT_SYMBOL(inode_sub_bytes);
 446
 447 loff_t inode_get_bytes(struct inode *inode)
 448 {
 449         loff_t ret;
 450
 451         spin_lock(&inode->i_lock);
 452         ret = (((loff_t)inode->i_blocks) << 9) + inode->i_bytes;
 453         spin_unlock(&inode->i_lock);
 454         return ret;
 455 }
 456
 457 EXPORT_SYMBOL(inode_get_bytes);
 458
 459 void inode_set_bytes(struct inode *inode, loff_t bytes)
 460 {
 461         /* Caller is here responsible for sufficient locking
 462          * (ie. inode->i_lock) */
 463         inode->i_blocks = bytes >> 9;
 464         inode->i_bytes = bytes & 511;
 465 }
 466
 467 EXPORT_SYMBOL(inode_set_bytes);