fs/stat.c

   1 /*
   2  *  linux/fs/stat.c
   3  *
   4  *  Copyright (C) 1991, 1992  Linus Torvalds
   5  */
   6
   7 #include <linux/mm.h>
   8 #include <linux/errno.h>
   9 #include <linux/file.h>
  10 #include <linux/smp_lock.h>
  11 #include <linux/highuid.h>
  12
  13 #include <asm/uaccess.h>
  14
  15 /*
  16  * Revalidate the inode. This is required for proper NFS attribute caching.
  17  */
  18 static __inline__ int
  19 do_revalidate(struct dentry *dentry)
  20 {
  21         struct inode * inode = dentry->d_inode;
  22         if (inode->i_op && inode->i_op->revalidate)
  23                 return inode->i_op->revalidate(dentry);
  24         return 0;
  25 }
  26
  27
  28 #if !defined(__alpha__) && !defined(__sparc__) && !defined(__ia64__) && !defined(__s390__) && !defined(__hppa__)
  29
  30 /*
  31  * For backward compatibility?  Maybe this should be moved
  32  * into arch/i386 instead?
  33  */
  34 static int cp_old_stat(struct inode * inode, struct __old_kernel_stat * statbuf)
  35 {
  36         static int warncount = 5;
  37         struct __old_kernel_stat tmp;
  38
  39         if (warncount > 0) {
  40                 warncount--;
  41                 printk("VFS: Warning: %s using old stat() call. Recompile your binary.\n",
  42                         current->comm);
  43         } else if (warncount < 0) {
  44                 /* it's laughable, but... */
  45                 warncount = 0;
  46         }
  47
  48         tmp.st_dev = kdev_t_to_nr(inode->i_dev);
  49         tmp.st_ino = inode->i_ino;
  50         tmp.st_mode = inode->i_mode;
  51         tmp.st_nlink = inode->i_nlink;
  52         SET_OLDSTAT_UID(tmp, inode->i_uid);
  53         SET_OLDSTAT_GID(tmp, inode->i_gid);
  54         tmp.st_rdev = kdev_t_to_nr(inode->i_rdev);
  55 #if BITS_PER_LONG == 32
  56         if (inode->i_size > 0x7fffffff)
  57                 return -EOVERFLOW;
  58 #endif
  59         tmp.st_size = inode->i_size;
  60         tmp.st_atime = inode->i_atime;
  61         tmp.st_mtime = inode->i_mtime;
  62         tmp.st_ctime = inode->i_ctime;
  63         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
  64 }
  65
  66 #endif
  67
  68 static int cp_new_stat(struct inode * inode, struct stat * statbuf)
  69 {
  70         struct stat tmp;
  71         unsigned int blocks, indirect;
  72
  73         memset(&tmp, 0, sizeof(tmp));
  74         tmp.st_dev = kdev_t_to_nr(inode->i_dev);
  75         tmp.st_ino = inode->i_ino;
  76         tmp.st_mode = inode->i_mode;
  77         tmp.st_nlink = inode->i_nlink;
  78         SET_STAT_UID(tmp, inode->i_uid);
  79         SET_STAT_GID(tmp, inode->i_gid);
  80         tmp.st_rdev = kdev_t_to_nr(inode->i_rdev);
  81 #if BITS_PER_LONG == 32
  82         if (inode->i_size > 0x7fffffff)
  83                 return -EOVERFLOW;
  84 #endif
  85         tmp.st_size = inode->i_size;
  86         tmp.st_atime = inode->i_atime;
  87         tmp.st_mtime = inode->i_mtime;
  88         tmp.st_ctime = inode->i_ctime;
  89 /*
  90  * st_blocks and st_blksize are approximated with a simple algorithm if
  91  * they aren't supported directly by the filesystem. The minix and msdos
  92  * filesystems don't keep track of blocks, so they would either have to
  93  * be counted explicitly (by delving into the file itself), or by using
  94  * this simple algorithm to get a reasonable (although not 100% accurate)
  95  * value.
  96  */
  97
  98 /*
  99  * Use minix fs values for the number of direct and indirect blocks.  The
 100  * count is now exact for the minix fs except that it counts zero blocks.
 101  * Everything is in units of BLOCK_SIZE until the assignment to
 102  * tmp.st_blksize.
 103  */
 104 #define D_B   7
 105 #define I_B   (BLOCK_SIZE / sizeof(unsigned short))
 106
 107         if (!inode->i_blksize) {
 108                 blocks = (tmp.st_size + BLOCK_SIZE - 1) / BLOCK_SIZE;
 109                 if (blocks > D_B) {
 110                         indirect = (blocks - D_B + I_B - 1) / I_B;
 111                         blocks += indirect;
 112                         if (indirect > 1) {
 113                                 indirect = (indirect - 1 + I_B - 1) / I_B;
 114                                 blocks += indirect;
 115                                 if (indirect > 1)
 116                                         blocks++;
 117                         }
 118                 }
 119                 tmp.st_blocks = (BLOCK_SIZE / 512) * blocks;
 120                 tmp.st_blksize = BLOCK_SIZE;
 121         } else {
 122                 tmp.st_blocks = inode->i_blocks;
 123                 tmp.st_blksize = inode->i_blksize;
 124         }
 125         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
 126 }
 127
 128
 129 #if !defined(__alpha__) && !defined(__sparc__) && !defined(__ia64__) && !defined(__s390__) && !defined(__hppa__)
 130 /*
 131  * For backward compatibility?  Maybe this should be moved
 132  * into arch/i386 instead?
 133  */
 134 asmlinkage long sys_stat(char * filename, struct __old_kernel_stat * statbuf)
 135 {
 136         struct nameidata nd;
 137         int error;
 138
 139         error = user_path_walk(filename, &nd);
 140         if (!error) {
 141                 error = do_revalidate(nd.dentry);
 142                 if (!error)
 143                         error = cp_old_stat(nd.dentry->d_inode, statbuf);
 144                 path_release(&nd);
 145         }
 146         return error;
 147 }
 148 #endif
 149
 150 asmlinkage long sys_newstat(char * filename, struct stat * statbuf)
 151 {
 152         struct nameidata nd;
 153         int error;
 154
 155         error = user_path_walk(filename, &nd);
 156         if (!error) {
 157                 error = do_revalidate(nd.dentry);
 158                 if (!error)
 159                         error = cp_new_stat(nd.dentry->d_inode, statbuf);
 160                 path_release(&nd);
 161         }
 162         return error;
 163 }
 164
 165 #if !defined(__alpha__) && !defined(__sparc__) && !defined(__ia64__) && !defined(__s390__) && !defined(__hppa__)
 166
 167 /*
 168  * For backward compatibility?  Maybe this should be moved
 169  * into arch/i386 instead?
 170  */
 171 asmlinkage long sys_lstat(char * filename, struct __old_kernel_stat * statbuf)
 172 {
 173         struct nameidata nd;
 174         int error;
 175
 176         error = user_path_walk_link(filename, &nd);
 177         if (!error) {
 178                 error = do_revalidate(nd.dentry);
 179                 if (!error)
 180                         error = cp_old_stat(nd.dentry->d_inode, statbuf);
 181                 path_release(&nd);
 182         }
 183         return error;
 184 }
 185
 186 #endif
 187
 188 asmlinkage long sys_newlstat(char * filename, struct stat * statbuf)
 189 {
 190         struct nameidata nd;
 191         int error;
 192
 193         error = user_path_walk_link(filename, &nd);
 194         if (!error) {
 195                 error = do_revalidate(nd.dentry);
 196                 if (!error)
 197                         error = cp_new_stat(nd.dentry->d_inode, statbuf);
 198                 path_release(&nd);
 199         }
 200         return error;
 201 }
 202
 203 #if !defined(__alpha__) && !defined(__sparc__) && !defined(__ia64__) && !defined(__s390__) && !defined(__hppa__)
 204
 205 /*
 206  * For backward compatibility?  Maybe this should be moved
 207  * into arch/i386 instead?
 208  */
 209 asmlinkage long sys_fstat(unsigned int fd, struct __old_kernel_stat * statbuf)
 210 {
 211         struct file * f;
 212         int err = -EBADF;
 213
 214         f = fget(fd);
 215         if (f) {
 216                 struct dentry * dentry = f->f_dentry;
 217
 218                 err = do_revalidate(dentry);
 219                 if (!err)
 220                         err = cp_old_stat(dentry->d_inode, statbuf);
 221                 fput(f);
 222         }
 223         return err;
 224 }
 225
 226 #endif
 227
 228 asmlinkage long sys_newfstat(unsigned int fd, struct stat * statbuf)
 229 {
 230         struct file * f;
 231         int err = -EBADF;
 232
 233         f = fget(fd);
 234         if (f) {
 235                 struct dentry * dentry = f->f_dentry;
 236
 237                 err = do_revalidate(dentry);
 238                 if (!err)
 239                         err = cp_new_stat(dentry->d_inode, statbuf);
 240                 fput(f);
 241         }
 242         return err;
 243 }
 244
 245 asmlinkage long sys_readlink(const char * path, char * buf, int bufsiz)
 246 {
 247         struct nameidata nd;
 248         int error;
 249
 250         if (bufsiz <= 0)
 251                 return -EINVAL;
 252
 253         error = user_path_walk_link(path, &nd);
 254         if (!error) {
 255                 struct inode * inode = nd.dentry->d_inode;
 256
 257                 error = -EINVAL;
 258                 if (inode->i_op && inode->i_op->readlink &&
 259                     !(error = do_revalidate(nd.dentry))) {
 260                         UPDATE_ATIME(inode);
 261                         error = inode->i_op->readlink(nd.dentry, buf, bufsiz);
 262                 }
 263                 path_release(&nd);
 264         }
 265         return error;
 266 }
 267
 268
 269 /* ---------- LFS-64 ----------- */
 270 #if !defined(__alpha__) && !defined (__ia64__) && !defined(__mips64)
 271
 272 static long cp_new_stat64(struct inode * inode, struct stat64 * statbuf)
 273 {
 274         struct stat64 tmp;
 275         unsigned int blocks, indirect;
 276
 277         memset(&tmp, 0, sizeof(tmp));
 278         tmp.st_dev = kdev_t_to_nr(inode->i_dev);
 279         tmp.st_ino = inode->i_ino;
 280 #ifdef STAT64_HAS_BROKEN_ST_INO
 281         tmp.__st_ino = inode->i_ino;
 282 #endif
 283         tmp.st_mode = inode->i_mode;
 284         tmp.st_nlink = inode->i_nlink;
 285         tmp.st_uid = inode->i_uid;
 286         tmp.st_gid = inode->i_gid;
 287         tmp.st_rdev = kdev_t_to_nr(inode->i_rdev);
 288         tmp.st_atime = inode->i_atime;
 289         tmp.st_mtime = inode->i_mtime;
 290         tmp.st_ctime = inode->i_ctime;
 291         tmp.st_size = inode->i_size;
 292 /*
 293  * st_blocks and st_blksize are approximated with a simple algorithm if
 294  * they aren't supported directly by the filesystem. The minix and msdos
 295  * filesystems don't keep track of blocks, so they would either have to
 296  * be counted explicitly (by delving into the file itself), or by using
 297  * this simple algorithm to get a reasonable (although not 100% accurate)
 298  * value.
 299  */
 300
 301 /*
 302  * Use minix fs values for the number of direct and indirect blocks.  The
 303  * count is now exact for the minix fs except that it counts zero blocks.
 304  * Everything is in units of BLOCK_SIZE until the assignment to
 305  * tmp.st_blksize.
 306  */
 307 #define D_B   7
 308 #define I_B   (BLOCK_SIZE / sizeof(unsigned short))
 309
 310         if (!inode->i_blksize) {
 311                 blocks = (tmp.st_size + BLOCK_SIZE - 1) >> BLOCK_SIZE_BITS;
 312                 if (blocks > D_B) {
 313                         indirect = (blocks - D_B + I_B - 1) / I_B;
 314                         blocks += indirect;
 315                         if (indirect > 1) {
 316                                 indirect = (indirect - 1 + I_B - 1) / I_B;
 317                                 blocks += indirect;
 318                                 if (indirect > 1)
 319                                         blocks++;
 320                         }
 321                 }
 322                 tmp.st_blocks = (BLOCK_SIZE / 512) * blocks;
 323                 tmp.st_blksize = BLOCK_SIZE;
 324         } else {
 325                 tmp.st_blocks = inode->i_blocks;
 326                 tmp.st_blksize = inode->i_blksize;
 327         }
 328         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
 329 }
 330
 331 asmlinkage long sys_stat64(char * filename, struct stat64 * statbuf, long flags)
 332 {
 333         struct nameidata nd;
 334         int error;
 335
 336         error = user_path_walk(filename, &nd);
 337         if (!error) {
 338                 error = do_revalidate(nd.dentry);
 339                 if (!error)
 340                         error = cp_new_stat64(nd.dentry->d_inode, statbuf);
 341                 path_release(&nd);
 342         }
 343         return error;
 344 }
 345
 346 asmlinkage long sys_lstat64(char * filename, struct stat64 * statbuf, long flags)
 347 {
 348         struct nameidata nd;
 349         int error;
 350
 351         error = user_path_walk_link(filename, &nd);
 352         if (!error) {
 353                 error = do_revalidate(nd.dentry);
 354                 if (!error)
 355                         error = cp_new_stat64(nd.dentry->d_inode, statbuf);
 356                 path_release(&nd);
 357         }
 358         return error;
 359 }
 360
 361 asmlinkage long sys_fstat64(unsigned long fd, struct stat64 * statbuf, long flags)
 362 {
 363         struct file * f;
 364         int err = -EBADF;
 365
 366         f = fget(fd);
 367         if (f) {
 368                 struct dentry * dentry = f->f_dentry;
 369
 370                 err = do_revalidate(dentry);
 371                 if (!err)
 372                         err = cp_new_stat64(dentry->d_inode, statbuf);
 373                 fput(f);
 374         }
 375         return err;
 376 }
 377
 378 #endif /* LFS-64 */