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/mm.h>
   9 #include <linux/errno.h>
  10 #include <linux/file.h>
  11 #include <linux/smp_lock.h>
  12 #include <linux/highuid.h>
  13 #include <linux/fs.h>
  14
  15 #include <asm/uaccess.h>
  16
  17 /*
  18  * Revalidate the inode. This is required for proper NFS attribute caching.
  19  */
  20 static __inline__ int
  21 do_revalidate(struct dentry *dentry)
  22 {
  23         struct inode * inode = dentry->d_inode;
  24         if (inode->i_op && inode->i_op->revalidate)
  25                 return inode->i_op->revalidate(dentry);
  26         return 0;
  27 }
  28
  29 static int do_getattr(struct vfsmount *mnt, struct dentry *dentry, struct kstat *stat)
  30 {
  31         int res = 0;
  32         unsigned int blocks, indirect;
  33         struct inode *inode = dentry->d_inode;
  34
  35         res = do_revalidate(dentry);
  36         if (res)
  37                 return res;
  38
  39         stat->dev = kdev_t_to_nr(inode->i_dev);
  40         stat->ino = inode->i_ino;
  41         stat->mode = inode->i_mode;
  42         stat->nlink = inode->i_nlink;
  43         stat->uid = inode->i_uid;
  44         stat->gid = inode->i_gid;
  45         stat->rdev = kdev_t_to_nr(inode->i_rdev);
  46         stat->atime = inode->i_atime;
  47         stat->mtime = inode->i_mtime;
  48         stat->ctime = inode->i_ctime;
  49         stat->ctime = inode->i_ctime;
  50         stat->size = inode->i_size;
  51 /*
  52  * st_blocks and st_blksize are approximated with a simple algorithm if
  53  * they aren't supported directly by the filesystem. The minix and msdos
  54  * filesystems don't keep track of blocks, so they would either have to
  55  * be counted explicitly (by delving into the file itself), or by using
  56  * this simple algorithm to get a reasonable (although not 100% accurate)
  57  * value.
  58  */
  59
  60 /*
  61  * Use minix fs values for the number of direct and indirect blocks.  The
  62  * count is now exact for the minix fs except that it counts zero blocks.
  63  * Everything is in units of BLOCK_SIZE until the assignment to
  64  * tmp.st_blksize.
  65  */
  66 #define D_B   7
  67 #define I_B   (BLOCK_SIZE / sizeof(unsigned short))
  68
  69         if (!inode->i_blksize) {
  70                 blocks = (stat->size + BLOCK_SIZE - 1) >> BLOCK_SIZE_BITS;
  71                 if (blocks > D_B) {
  72                         indirect = (blocks - D_B + I_B - 1) / I_B;
  73                         blocks += indirect;
  74                         if (indirect > 1) {
  75                                 indirect = (indirect - 1 + I_B - 1) / I_B;
  76                                 blocks += indirect;
  77                                 if (indirect > 1)
  78                                         blocks++;
  79                         }
  80                 }
  81                 stat->blocks = (BLOCK_SIZE / 512) * blocks;
  82                 stat->blksize = BLOCK_SIZE;
  83         } else {
  84                 stat->blocks = inode->i_blocks;
  85                 stat->blksize = inode->i_blksize;
  86         }
  87         return 0;
  88 }
  89
  90 int vfs_stat(char *name, struct kstat *stat)
  91 {
  92         struct nameidata nd;
  93         int error;
  94
  95         error = user_path_walk(name, &nd);
  96         if (!error) {
  97                 error = do_getattr(nd.mnt, nd.dentry, stat);
  98                 path_release(&nd);
  99         }
 100         return error;
 101 }
 102
 103 int vfs_lstat(char *name, struct kstat *stat)
 104 {
 105         struct nameidata nd;
 106         int error;
 107
 108         error = user_path_walk_link(name, &nd);
 109         if (!error) {
 110                 error = do_getattr(nd.mnt, nd.dentry, stat);
 111                 path_release(&nd);
 112         }
 113         return error;
 114 }
 115
 116 int vfs_fstat(unsigned int fd, struct kstat *stat)
 117 {
 118         struct file *f = fget(fd);
 119         int error = -EBADF;
 120
 121         if (f) {
 122                 error = do_getattr(f->f_vfsmnt, f->f_dentry, stat);
 123                 fput(f);
 124         }
 125         return error;
 126 }
 127
 128 #if !defined(__alpha__) && !defined(__sparc__) && !defined(__ia64__) \
 129  && !defined(CONFIG_ARCH_S390) && !defined(__hppa__) && !defined(__x86_64__) \
 130  && !defined(__arm__)
 131
 132 /*
 133  * For backward compatibility?  Maybe this should be moved
 134  * into arch/i386 instead?
 135  */
 136 static int cp_old_stat(struct kstat *stat, struct __old_kernel_stat * statbuf)
 137 {
 138         static int warncount = 5;
 139         struct __old_kernel_stat tmp;
 140
 141         if (warncount > 0) {
 142                 warncount--;
 143                 printk(KERN_WARNING "VFS: Warning: %s using old stat() call. Recompile your binary.\n",
 144                         current->comm);
 145         } else if (warncount < 0) {
 146                 /* it's laughable, but... */
 147                 warncount = 0;
 148         }
 149
 150         tmp.st_dev = stat->dev;
 151         tmp.st_ino = stat->ino;
 152         tmp.st_mode = stat->mode;
 153         tmp.st_nlink = stat->nlink;
 154         SET_OLDSTAT_UID(tmp, stat->uid);
 155         SET_OLDSTAT_GID(tmp, stat->gid);
 156         tmp.st_rdev = stat->rdev;
 157 #if BITS_PER_LONG == 32
 158         if (stat->size > MAX_NON_LFS)
 159                 return -EOVERFLOW;
 160 #endif
 161         tmp.st_size = stat->size;
 162         tmp.st_atime = stat->atime;
 163         tmp.st_mtime = stat->mtime;
 164         tmp.st_ctime = stat->ctime;
 165         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
 166 }
 167
 168 asmlinkage long sys_stat(char * filename, struct __old_kernel_stat * statbuf)
 169 {
 170         struct kstat stat;
 171         int error = vfs_stat(filename, &stat);
 172
 173         if (!error)
 174                 error = cp_old_stat(&stat, statbuf);
 175
 176         return error;
 177 }
 178 asmlinkage long sys_lstat(char * filename, struct __old_kernel_stat * statbuf)
 179 {
 180         struct kstat stat;
 181         int error = vfs_lstat(filename, &stat);
 182
 183         if (!error)
 184                 error = cp_old_stat(&stat, statbuf);
 185
 186         return error;
 187 }
 188 asmlinkage long sys_fstat(unsigned int fd, struct __old_kernel_stat * statbuf)
 189 {
 190         struct kstat stat;
 191         int error = vfs_fstat(fd, &stat);
 192
 193         if (!error)
 194                 error = cp_old_stat(&stat, statbuf);
 195
 196         return error;
 197 }
 198
 199 #endif
 200
 201 static int cp_new_stat(struct kstat *stat, struct stat *statbuf)
 202 {
 203         struct stat tmp;
 204
 205         memset(&tmp, 0, sizeof(tmp));
 206         tmp.st_dev = stat->dev;
 207         tmp.st_ino = stat->ino;
 208         tmp.st_mode = stat->mode;
 209         tmp.st_nlink = stat->nlink;
 210         SET_STAT_UID(tmp, stat->uid);
 211         SET_STAT_GID(tmp, stat->gid);
 212         tmp.st_rdev = stat->rdev;
 213 #if BITS_PER_LONG == 32
 214         if (stat->size > MAX_NON_LFS)
 215                 return -EOVERFLOW;
 216 #endif
 217         tmp.st_size = stat->size;
 218         tmp.st_atime = stat->atime;
 219         tmp.st_mtime = stat->mtime;
 220         tmp.st_ctime = stat->ctime;
 221         tmp.st_blocks = stat->blocks;
 222         tmp.st_blksize = stat->blksize;
 223         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
 224 }
 225
 226 asmlinkage long sys_newstat(char * filename, struct stat * statbuf)
 227 {
 228         struct kstat stat;
 229         int error = vfs_stat(filename, &stat);
 230
 231         if (!error)
 232                 error = cp_new_stat(&stat, statbuf);
 233
 234         return error;
 235 }
 236 asmlinkage long sys_newlstat(char * filename, struct stat * statbuf)
 237 {
 238         struct kstat stat;
 239         int error = vfs_lstat(filename, &stat);
 240
 241         if (!error)
 242                 error = cp_new_stat(&stat, statbuf);
 243
 244         return error;
 245 }
 246 asmlinkage long sys_newfstat(unsigned int fd, struct stat * statbuf)
 247 {
 248         struct kstat stat;
 249         int error = vfs_fstat(fd, &stat);
 250
 251         if (!error)
 252                 error = cp_new_stat(&stat, statbuf);
 253
 254         return error;
 255 }
 256
 257 asmlinkage long sys_readlink(const char * path, char * buf, int bufsiz)
 258 {
 259         struct nameidata nd;
 260         int error;
 261
 262         if (bufsiz <= 0)
 263                 return -EINVAL;
 264
 265         error = user_path_walk_link(path, &nd);
 266         if (!error) {
 267                 struct inode * inode = nd.dentry->d_inode;
 268
 269                 error = -EINVAL;
 270                 if (inode->i_op && inode->i_op->readlink &&
 271                     !(error = do_revalidate(nd.dentry))) {
 272                         UPDATE_ATIME(inode);
 273                         error = inode->i_op->readlink(nd.dentry, buf, bufsiz);
 274                 }
 275                 path_release(&nd);
 276         }
 277         return error;
 278 }
 279
 280
 281 /* ---------- LFS-64 ----------- */
 282 #if !defined(__alpha__) && !defined(__ia64__) && !defined(__mips64) && !defined(__x86_64__) && !defined(CONFIG_ARCH_S390X)
 283
 284 static long cp_new_stat64(struct kstat *stat, struct stat64 *statbuf)
 285 {
 286         struct stat64 tmp;
 287
 288         memset(&tmp, 0, sizeof(tmp));
 289         tmp.st_dev = stat->dev;
 290         tmp.st_ino = stat->ino;
 291 #ifdef STAT64_HAS_BROKEN_ST_INO
 292         tmp.__st_ino = stat->ino;
 293 #endif
 294         tmp.st_mode = stat->mode;
 295         tmp.st_nlink = stat->nlink;
 296         tmp.st_uid = stat->uid;
 297         tmp.st_gid = stat->gid;
 298         tmp.st_rdev = stat->rdev;
 299         tmp.st_atime = stat->atime;
 300         tmp.st_mtime = stat->mtime;
 301         tmp.st_ctime = stat->ctime;
 302         tmp.st_size = stat->size;
 303         tmp.st_blocks = stat->blocks;
 304         tmp.st_blksize = stat->blksize;
 305         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
 306 }
 307
 308 asmlinkage long sys_stat64(char * filename, struct stat64 * statbuf, long flags)
 309 {
 310         struct kstat stat;
 311         int error = vfs_stat(filename, &stat);
 312
 313         if (!error)
 314                 error = cp_new_stat64(&stat, statbuf);
 315
 316         return error;
 317 }
 318 asmlinkage long sys_lstat64(char * filename, struct stat64 * statbuf, long flags)
 319 {
 320         struct kstat stat;
 321         int error = vfs_lstat(filename, &stat);
 322
 323         if (!error)
 324                 error = cp_new_stat64(&stat, statbuf);
 325
 326         return error;
 327 }
 328 asmlinkage long sys_fstat64(unsigned long fd, struct stat64 * statbuf, long flags)
 329 {
 330         struct kstat stat;
 331         int error = vfs_fstat(fd, &stat);
 332
 333         if (!error)
 334                 error = cp_new_stat64(&stat, statbuf);
 335
 336         return error;
 337 }
 338
 339 #endif /* LFS-64 */