fs/stat.c

   1 /*
   2  *  linux/fs/stat.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 #include <linux/config.h>
   8 #include <linux/module.h>
   9 #include <linux/mm.h>
  10 #include <linux/errno.h>
  11 #include <linux/file.h>
  12 #include <linux/smp_lock.h>
  13 #include <linux/highuid.h>
  14 #include <linux/fs.h>
  15 #include <linux/namei.h>
  16 #include <linux/security.h>
  17 #include <linux/syscalls.h>
  18
  19 #include <asm/uaccess.h>
  20 #include <asm/unistd.h>
  21
  22 void generic_fillattr(struct inode *inode, struct kstat *stat)
  23 {
  24         stat->dev = inode->i_sb->s_dev;
  25         stat->ino = inode->i_ino;
  26         stat->mode = inode->i_mode;
  27         stat->nlink = inode->i_nlink;
  28         stat->uid = inode->i_uid;
  29         stat->gid = inode->i_gid;
  30         stat->rdev = inode->i_rdev;
  31         stat->atime = inode->i_atime;
  32         stat->mtime = inode->i_mtime;
  33         stat->ctime = inode->i_ctime;
  34         stat->size = i_size_read(inode);
  35         stat->blocks = inode->i_blocks;
  36         stat->blksize = inode->i_blksize;
  37 }
  38
  39 EXPORT_SYMBOL(generic_fillattr);
  40
  41 int vfs_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
  42 {
  43         struct inode *inode = dentry->d_inode;
  44         int retval;
  45
  46         retval = security_inode_getattr(mnt, dentry);
  47         if (retval)
  48                 return retval;
  49
  50         if (inode->i_op->getattr)
  51                 return inode->i_op->getattr(mnt, dentry, stat);
  52
  53         generic_fillattr(inode, stat);
  54         if (!stat->blksize) {
  55                 struct super_block *s = inode->i_sb;
  56                 unsigned blocks;
  57                 blocks = (stat->size+s->s_blocksize-1) >> s->s_blocksize_bits;
  58                 stat->blocks = (s->s_blocksize / 512) * blocks;
  59                 stat->blksize = s->s_blocksize;
  60         }
  61         return 0;
  62 }
  63
  64 EXPORT_SYMBOL(vfs_getattr);
  65
  66 int vfs_stat_fd(int dfd, char __user *name, struct kstat *stat)
  67 {
  68         struct nameidata nd;
  69         int error;
  70
  71         error = __user_walk_fd(dfd, name, LOOKUP_FOLLOW, &nd);
  72         if (!error) {
  73                 error = vfs_getattr(nd.mnt, nd.dentry, stat);
  74                 path_release(&nd);
  75         }
  76         return error;
  77 }
  78
  79 int vfs_stat(char __user *name, struct kstat *stat)
  80 {
  81         return vfs_stat_fd(AT_FDCWD, name, stat);
  82 }
  83
  84 EXPORT_SYMBOL(vfs_stat);
  85
  86 int vfs_lstat_fd(int dfd, char __user *name, struct kstat *stat)
  87 {
  88         struct nameidata nd;
  89         int error;
  90
  91         error = __user_walk_fd(dfd, name, 0, &nd);
  92         if (!error) {
  93                 error = vfs_getattr(nd.mnt, nd.dentry, stat);
  94                 path_release(&nd);
  95         }
  96         return error;
  97 }
  98
  99 int vfs_lstat(char __user *name, struct kstat *stat)
 100 {
 101         return vfs_lstat_fd(AT_FDCWD, name, stat);
 102 }
 103
 104 EXPORT_SYMBOL(vfs_lstat);
 105
 106 int vfs_fstat(unsigned int fd, struct kstat *stat)
 107 {
 108         struct file *f = fget(fd);
 109         int error = -EBADF;
 110
 111         if (f) {
 112                 error = vfs_getattr(f->f_vfsmnt, f->f_dentry, stat);
 113                 fput(f);
 114         }
 115         return error;
 116 }
 117
 118 EXPORT_SYMBOL(vfs_fstat);
 119
 120 #ifdef __ARCH_WANT_OLD_STAT
 121
 122 /*
 123  * For backward compatibility?  Maybe this should be moved
 124  * into arch/i386 instead?
 125  */
 126 static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat __user * statbuf)
 127 {
 128         static int warncount = 5;
 129         struct __old_kernel_stat tmp;
 130
 131         if (warncount > 0) {
 132                 warncount--;
 133                 printk(KERN_WARNING "VFS: Warning: %s using old stat() call. Recompile your binary.\n",
 134                         current->comm);
 135         } else if (warncount < 0) {
 136                 /* it's laughable, but... */
 137                 warncount = 0;
 138         }
 139
 140         memset(&tmp, 0, sizeof(struct __old_kernel_stat));
 141         tmp.st_dev = old_encode_dev(stat->dev);
 142         tmp.st_ino = stat->ino;
 143         tmp.st_mode = stat->mode;
 144         tmp.st_nlink = stat->nlink;
 145         if (tmp.st_nlink != stat->nlink)
 146                 return -EOVERFLOW;
 147         SET_UID(tmp.st_uid, stat->uid);
 148         SET_GID(tmp.st_gid, stat->gid);
 149         tmp.st_rdev = old_encode_dev(stat->rdev);
 150 #if BITS_PER_LONG == 32
 151         if (stat->size > MAX_NON_LFS)
 152                 return -EOVERFLOW;
 153 #endif
 154         tmp.st_size = stat->size;
 155         tmp.st_atime = stat->atime.tv_sec;
 156         tmp.st_mtime = stat->mtime.tv_sec;
 157         tmp.st_ctime = stat->ctime.tv_sec;
 158         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
 159 }
 160
 161 asmlinkage long sys_stat(char __user * filename, struct __old_kernel_stat __user * statbuf)
 162 {
 163         struct kstat stat;
 164         int error = vfs_stat_fd(AT_FDCWD, filename, &stat);
 165
 166         if (!error)
 167                 error = cp_old_stat(&stat, statbuf);
 168
 169         return error;
 170 }
 171 asmlinkage long sys_lstat(char __user * filename, struct __old_kernel_stat __user * statbuf)
 172 {
 173         struct kstat stat;
 174         int error = vfs_lstat_fd(AT_FDCWD, filename, &stat);
 175
 176         if (!error)
 177                 error = cp_old_stat(&stat, statbuf);
 178
 179         return error;
 180 }
 181 asmlinkage long sys_fstat(unsigned int fd, struct __old_kernel_stat __user * statbuf)
 182 {
 183         struct kstat stat;
 184         int error = vfs_fstat(fd, &stat);
 185
 186         if (!error)
 187                 error = cp_old_stat(&stat, statbuf);
 188
 189         return error;
 190 }
 191
 192 #endif /* __ARCH_WANT_OLD_STAT */
 193
 194 static int cp_new_stat(struct kstat *stat, struct stat __user *statbuf)
 195 {
 196         struct stat tmp;
 197
 198 #if BITS_PER_LONG == 32
 199         if (!old_valid_dev(stat->dev) || !old_valid_dev(stat->rdev))
 200                 return -EOVERFLOW;
 201 #else
 202         if (!new_valid_dev(stat->dev) || !new_valid_dev(stat->rdev))
 203                 return -EOVERFLOW;
 204 #endif
 205
 206         memset(&tmp, 0, sizeof(tmp));
 207 #if BITS_PER_LONG == 32
 208         tmp.st_dev = old_encode_dev(stat->dev);
 209 #else
 210         tmp.st_dev = new_encode_dev(stat->dev);
 211 #endif
 212         tmp.st_ino = stat->ino;
 213         tmp.st_mode = stat->mode;
 214         tmp.st_nlink = stat->nlink;
 215         if (tmp.st_nlink != stat->nlink)
 216                 return -EOVERFLOW;
 217         SET_UID(tmp.st_uid, stat->uid);
 218         SET_GID(tmp.st_gid, stat->gid);
 219 #if BITS_PER_LONG == 32
 220         tmp.st_rdev = old_encode_dev(stat->rdev);
 221 #else
 222         tmp.st_rdev = new_encode_dev(stat->rdev);
 223 #endif
 224 #if BITS_PER_LONG == 32
 225         if (stat->size > MAX_NON_LFS)
 226                 return -EOVERFLOW;
 227 #endif
 228         tmp.st_size = stat->size;
 229         tmp.st_atime = stat->atime.tv_sec;
 230         tmp.st_mtime = stat->mtime.tv_sec;
 231         tmp.st_ctime = stat->ctime.tv_sec;
 232 #ifdef STAT_HAVE_NSEC
 233         tmp.st_atime_nsec = stat->atime.tv_nsec;
 234         tmp.st_mtime_nsec = stat->mtime.tv_nsec;
 235         tmp.st_ctime_nsec = stat->ctime.tv_nsec;
 236 #endif
 237         tmp.st_blocks = stat->blocks;
 238         tmp.st_blksize = stat->blksize;
 239         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
 240 }
 241
 242 asmlinkage long sys_newstat(char __user *filename, struct stat __user *statbuf)
 243 {
 244         struct kstat stat;
 245         int error = vfs_stat_fd(AT_FDCWD, filename, &stat);
 246
 247         if (!error)
 248                 error = cp_new_stat(&stat, statbuf);
 249
 250         return error;
 251 }
 252
 253 asmlinkage long sys_newlstat(char __user *filename, struct stat __user *statbuf)
 254 {
 255         struct kstat stat;
 256         int error = vfs_lstat_fd(AT_FDCWD, filename, &stat);
 257
 258         if (!error)
 259                 error = cp_new_stat(&stat, statbuf);
 260
 261         return error;
 262 }
 263
 264 asmlinkage long sys_newfstatat(int dfd, char __user *filename,
 265                                 struct stat __user *statbuf, int flag)
 266 {
 267         struct kstat stat;
 268         int error = -EINVAL;
 269
 270         if ((flag & ~AT_SYMLINK_NOFOLLOW) != 0)
 271                 goto out;
 272
 273         if (flag & AT_SYMLINK_NOFOLLOW)
 274                 error = vfs_lstat_fd(dfd, filename, &stat);
 275         else
 276                 error = vfs_stat_fd(dfd, filename, &stat);
 277
 278         if (!error)
 279                 error = cp_new_stat(&stat, statbuf);
 280
 281 out:
 282         return error;
 283 }
 284
 285 asmlinkage long sys_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 asmlinkage long sys_readlinkat(int dfd, const char __user *path,
 297                                 char __user *buf, int bufsiz)
 298 {
 299         struct nameidata nd;
 300         int error;
 301
 302         if (bufsiz <= 0)
 303                 return -EINVAL;
 304
 305         error = __user_walk_fd(dfd, path, 0, &nd);
 306         if (!error) {
 307                 struct inode * inode = nd.dentry->d_inode;
 308
 309                 error = -EINVAL;
 310                 if (inode->i_op && inode->i_op->readlink) {
 311                         error = security_inode_readlink(nd.dentry);
 312                         if (!error) {
 313                                 touch_atime(nd.mnt, nd.dentry);
 314                                 error = inode->i_op->readlink(nd.dentry, buf, bufsiz);
 315                         }
 316                 }
 317                 path_release(&nd);
 318         }
 319         return error;
 320 }
 321
 322 asmlinkage long sys_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 #ifdef STAT64_HAS_BROKEN_ST_INO
 349         tmp.__st_ino = stat->ino;
 350 #endif
 351         tmp.st_mode = stat->mode;
 352         tmp.st_nlink = stat->nlink;
 353         tmp.st_uid = stat->uid;
 354         tmp.st_gid = stat->gid;
 355         tmp.st_atime = stat->atime.tv_sec;
 356         tmp.st_atime_nsec = stat->atime.tv_nsec;
 357         tmp.st_mtime = stat->mtime.tv_sec;
 358         tmp.st_mtime_nsec = stat->mtime.tv_nsec;
 359         tmp.st_ctime = stat->ctime.tv_sec;
 360         tmp.st_ctime_nsec = stat->ctime.tv_nsec;
 361         tmp.st_size = stat->size;
 362         tmp.st_blocks = stat->blocks;
 363         tmp.st_blksize = stat->blksize;
 364         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
 365 }
 366
 367 asmlinkage long sys_stat64(char __user * filename, struct stat64 __user * statbuf)
 368 {
 369         struct kstat stat;
 370         int error = vfs_stat(filename, &stat);
 371
 372         if (!error)
 373                 error = cp_new_stat64(&stat, statbuf);
 374
 375         return error;
 376 }
 377 asmlinkage long sys_lstat64(char __user * filename, struct stat64 __user * statbuf)
 378 {
 379         struct kstat stat;
 380         int error = vfs_lstat(filename, &stat);
 381
 382         if (!error)
 383                 error = cp_new_stat64(&stat, statbuf);
 384
 385         return error;
 386 }
 387 asmlinkage long sys_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 #endif /* __ARCH_WANT_STAT64 */
 399
 400 void inode_add_bytes(struct inode *inode, loff_t bytes)
 401 {
 402         spin_lock(&inode->i_lock);
 403         inode->i_blocks += bytes >> 9;
 404         bytes &= 511;
 405         inode->i_bytes += bytes;
 406         if (inode->i_bytes >= 512) {
 407                 inode->i_blocks++;
 408                 inode->i_bytes -= 512;
 409         }
 410         spin_unlock(&inode->i_lock);
 411 }
 412
 413 EXPORT_SYMBOL(inode_add_bytes);
 414
 415 void inode_sub_bytes(struct inode *inode, loff_t bytes)
 416 {
 417         spin_lock(&inode->i_lock);
 418         inode->i_blocks -= bytes >> 9;
 419         bytes &= 511;
 420         if (inode->i_bytes < bytes) {
 421                 inode->i_blocks--;
 422                 inode->i_bytes += 512;
 423         }
 424         inode->i_bytes -= bytes;
 425         spin_unlock(&inode->i_lock);
 426 }
 427
 428 EXPORT_SYMBOL(inode_sub_bytes);
 429
 430 loff_t inode_get_bytes(struct inode *inode)
 431 {
 432         loff_t ret;
 433
 434         spin_lock(&inode->i_lock);
 435         ret = (((loff_t)inode->i_blocks) << 9) + inode->i_bytes;
 436         spin_unlock(&inode->i_lock);
 437         return ret;
 438 }
 439
 440 EXPORT_SYMBOL(inode_get_bytes);
 441
 442 void inode_set_bytes(struct inode *inode, loff_t bytes)
 443 {
 444         /* Caller is here responsible for sufficient locking
 445          * (ie. inode->i_lock) */
 446         inode->i_blocks = bytes >> 9;
 447         inode->i_bytes = bytes & 511;
 448 }
 449
 450 EXPORT_SYMBOL(inode_set_bytes);