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