The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/fs/stat.c

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    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 
   14 #include <asm/uaccess.h>
   15 
   16 /*
   17  * Revalidate the inode. This is required for proper NFS attribute caching.
   18  */
   19 static __inline__ int
   20 do_revalidate(struct dentry *dentry)
   21 {
   22         struct inode * inode = dentry->d_inode;
   23         if (inode->i_op && inode->i_op->revalidate)
   24                 return inode->i_op->revalidate(dentry);
   25         return 0;
   26 }
   27 
   28 
   29 #if !defined(__alpha__) && !defined(__sparc__) && !defined(__ia64__) && !defined(CONFIG_ARCH_S390) && !defined(__hppa__) && !defined(__x86_64__)
   30 
   31 /*
   32  * For backward compatibility?  Maybe this should be moved
   33  * into arch/i386 instead?
   34  */
   35 static int cp_old_stat(struct inode * inode, struct __old_kernel_stat * statbuf)
   36 {
   37         static int warncount = 5;
   38         struct __old_kernel_stat tmp;
   39 
   40         memset(&tmp, 0, sizeof(struct __old_kernel_stat));
   41         
   42         if (warncount > 0) {
   43                 warncount--;
   44                 printk(KERN_WARNING "VFS: Warning: %s using old stat() call. Recompile your binary.\n",
   45                         current->comm);
   46         } else if (warncount < 0) {
   47                 /* it's laughable, but... */
   48                 warncount = 0;
   49         }
   50 
   51         tmp.st_dev = kdev_t_to_nr(inode->i_dev);
   52         tmp.st_ino = inode->i_ino;
   53         tmp.st_mode = inode->i_mode;
   54         tmp.st_nlink = inode->i_nlink;
   55         SET_OLDSTAT_UID(tmp, inode->i_uid);
   56         SET_OLDSTAT_GID(tmp, inode->i_gid);
   57         tmp.st_rdev = kdev_t_to_nr(inode->i_rdev);
   58 #if BITS_PER_LONG == 32
   59         if (inode->i_size > MAX_NON_LFS)
   60                 return -EOVERFLOW;
   61 #endif  
   62         tmp.st_size = inode->i_size;
   63         tmp.st_atime = inode->i_atime;
   64         tmp.st_mtime = inode->i_mtime;
   65         tmp.st_ctime = inode->i_ctime;
   66         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
   67 }
   68 
   69 #endif
   70 
   71 static int cp_new_stat(struct inode * inode, struct stat * statbuf)
   72 {
   73         struct stat tmp;
   74         unsigned int blocks, indirect;
   75 
   76         memset(&tmp, 0, sizeof(tmp));
   77         tmp.st_dev = kdev_t_to_nr(inode->i_dev);
   78         tmp.st_ino = inode->i_ino;
   79         tmp.st_mode = inode->i_mode;
   80         tmp.st_nlink = inode->i_nlink;
   81         SET_STAT_UID(tmp, inode->i_uid);
   82         SET_STAT_GID(tmp, inode->i_gid);
   83         tmp.st_rdev = kdev_t_to_nr(inode->i_rdev);
   84 #if BITS_PER_LONG == 32
   85         if (inode->i_size > MAX_NON_LFS)
   86                 return -EOVERFLOW;
   87 #endif  
   88         tmp.st_size = inode->i_size;
   89         tmp.st_atime = inode->i_atime;
   90         tmp.st_mtime = inode->i_mtime;
   91         tmp.st_ctime = inode->i_ctime;
   92 /*
   93  * st_blocks and st_blksize are approximated with a simple algorithm if
   94  * they aren't supported directly by the filesystem. The minix and msdos
   95  * filesystems don't keep track of blocks, so they would either have to
   96  * be counted explicitly (by delving into the file itself), or by using
   97  * this simple algorithm to get a reasonable (although not 100% accurate)
   98  * value.
   99  */
  100 
  101 /*
  102  * Use minix fs values for the number of direct and indirect blocks.  The
  103  * count is now exact for the minix fs except that it counts zero blocks.
  104  * Everything is in units of BLOCK_SIZE until the assignment to
  105  * tmp.st_blksize.
  106  */
  107 #define D_B   7
  108 #define I_B   (BLOCK_SIZE / sizeof(unsigned short))
  109 
  110         if (!inode->i_blksize) {
  111                 blocks = (tmp.st_size + BLOCK_SIZE - 1) / BLOCK_SIZE;
  112                 if (blocks > D_B) {
  113                         indirect = (blocks - D_B + I_B - 1) / I_B;
  114                         blocks += indirect;
  115                         if (indirect > 1) {
  116                                 indirect = (indirect - 1 + I_B - 1) / I_B;
  117                                 blocks += indirect;
  118                                 if (indirect > 1)
  119                                         blocks++;
  120                         }
  121                 }
  122                 tmp.st_blocks = (BLOCK_SIZE / 512) * blocks;
  123                 tmp.st_blksize = BLOCK_SIZE;
  124         } else {
  125                 tmp.st_blocks = inode->i_blocks;
  126                 tmp.st_blksize = inode->i_blksize;
  127         }
  128         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
  129 }
  130 
  131 
  132 #if !defined(__alpha__) && !defined(__sparc__) && !defined(__ia64__) && !defined(CONFIG_ARCH_S390) && !defined(__hppa__) && !defined(__x86_64__)
  133 /*
  134  * For backward compatibility?  Maybe this should be moved
  135  * into arch/i386 instead?
  136  */
  137 asmlinkage long sys_stat(char * filename, struct __old_kernel_stat * statbuf)
  138 {
  139         struct nameidata nd;
  140         int error;
  141 
  142         error = user_path_walk(filename, &nd);
  143         if (!error) {
  144                 error = do_revalidate(nd.dentry);
  145                 if (!error)
  146                         error = cp_old_stat(nd.dentry->d_inode, statbuf);
  147                 path_release(&nd);
  148         }
  149         return error;
  150 }
  151 #endif
  152 
  153 asmlinkage long sys_newstat(char * filename, struct stat * statbuf)
  154 {
  155         struct nameidata nd;
  156         int error;
  157 
  158         error = user_path_walk(filename, &nd);
  159         if (!error) {
  160                 error = do_revalidate(nd.dentry);
  161                 if (!error)
  162                         error = cp_new_stat(nd.dentry->d_inode, statbuf);
  163                 path_release(&nd);
  164         }
  165         return error;
  166 }
  167 
  168 #if !defined(__alpha__) && !defined(__sparc__) && !defined(__ia64__) && !defined(CONFIG_ARCH_S390) && !defined(__hppa__) && !defined(__x86_64__)
  169 
  170 /*
  171  * For backward compatibility?  Maybe this should be moved
  172  * into arch/i386 instead?
  173  */
  174 asmlinkage long sys_lstat(char * filename, struct __old_kernel_stat * statbuf)
  175 {
  176         struct nameidata nd;
  177         int error;
  178 
  179         error = user_path_walk_link(filename, &nd);
  180         if (!error) {
  181                 error = do_revalidate(nd.dentry);
  182                 if (!error)
  183                         error = cp_old_stat(nd.dentry->d_inode, statbuf);
  184                 path_release(&nd);
  185         }
  186         return error;
  187 }
  188 
  189 #endif
  190 
  191 asmlinkage long sys_newlstat(char * filename, struct stat * statbuf)
  192 {
  193         struct nameidata nd;
  194         int error;
  195 
  196         error = user_path_walk_link(filename, &nd);
  197         if (!error) {
  198                 error = do_revalidate(nd.dentry);
  199                 if (!error)
  200                         error = cp_new_stat(nd.dentry->d_inode, statbuf);
  201                 path_release(&nd);
  202         }
  203         return error;
  204 }
  205 
  206 #if !defined(__alpha__) && !defined(__sparc__) && !defined(__ia64__) && !defined(CONFIG_ARCH_S390) && !defined(__hppa__) && !defined(__x86_64__)
  207 
  208 /*
  209  * For backward compatibility?  Maybe this should be moved
  210  * into arch/i386 instead?
  211  */
  212 asmlinkage long sys_fstat(unsigned int fd, struct __old_kernel_stat * statbuf)
  213 {
  214         struct file * f;
  215         int err = -EBADF;
  216 
  217         f = fget(fd);
  218         if (f) {
  219                 struct dentry * dentry = f->f_dentry;
  220 
  221                 err = do_revalidate(dentry);
  222                 if (!err)
  223                         err = cp_old_stat(dentry->d_inode, statbuf);
  224                 fput(f);
  225         }
  226         return err;
  227 }
  228 
  229 #endif
  230 
  231 asmlinkage long sys_newfstat(unsigned int fd, struct stat * statbuf)
  232 {
  233         struct file * f;
  234         int err = -EBADF;
  235 
  236         f = fget(fd);
  237         if (f) {
  238                 struct dentry * dentry = f->f_dentry;
  239 
  240                 err = do_revalidate(dentry);
  241                 if (!err)
  242                         err = cp_new_stat(dentry->d_inode, statbuf);
  243                 fput(f);
  244         }
  245         return err;
  246 }
  247 
  248 asmlinkage long sys_readlink(const char * path, char * buf, int bufsiz)
  249 {
  250         struct nameidata nd;
  251         int error;
  252 
  253         if (bufsiz <= 0)
  254                 return -EINVAL;
  255 
  256         error = user_path_walk_link(path, &nd);
  257         if (!error) {
  258                 struct inode * inode = nd.dentry->d_inode;
  259 
  260                 error = -EINVAL;
  261                 if (inode->i_op && inode->i_op->readlink &&
  262                     !(error = do_revalidate(nd.dentry))) {
  263                         UPDATE_ATIME(inode);
  264                         error = inode->i_op->readlink(nd.dentry, buf, bufsiz);
  265                 }
  266                 path_release(&nd);
  267         }
  268         return error;
  269 }
  270 
  271 
  272 /* ---------- LFS-64 ----------- */
  273 #if !defined(__alpha__) && !defined(__ia64__) && !defined(__mips64) && !defined(__x86_64__) && !defined(CONFIG_ARCH_S390X)
  274 
  275 static long cp_new_stat64(struct inode * inode, struct stat64 * statbuf)
  276 {
  277         struct stat64 tmp;
  278         unsigned int blocks, indirect;
  279 
  280         memset(&tmp, 0, sizeof(tmp));
  281         tmp.st_dev = kdev_t_to_nr(inode->i_dev);
  282         tmp.st_ino = inode->i_ino;
  283 #ifdef STAT64_HAS_BROKEN_ST_INO
  284         tmp.__st_ino = inode->i_ino;
  285 #endif
  286         tmp.st_mode = inode->i_mode;
  287         tmp.st_nlink = inode->i_nlink;
  288         tmp.st_uid = inode->i_uid;
  289         tmp.st_gid = inode->i_gid;
  290         tmp.st_rdev = kdev_t_to_nr(inode->i_rdev);
  291         tmp.st_atime = inode->i_atime;
  292         tmp.st_mtime = inode->i_mtime;
  293         tmp.st_ctime = inode->i_ctime;
  294         tmp.st_size = inode->i_size;
  295 /*
  296  * st_blocks and st_blksize are approximated with a simple algorithm if
  297  * they aren't supported directly by the filesystem. The minix and msdos
  298  * filesystems don't keep track of blocks, so they would either have to
  299  * be counted explicitly (by delving into the file itself), or by using
  300  * this simple algorithm to get a reasonable (although not 100% accurate)
  301  * value.
  302  */
  303 
  304 /*
  305  * Use minix fs values for the number of direct and indirect blocks.  The
  306  * count is now exact for the minix fs except that it counts zero blocks.
  307  * Everything is in units of BLOCK_SIZE until the assignment to
  308  * tmp.st_blksize.
  309  */
  310 #define D_B   7
  311 #define I_B   (BLOCK_SIZE / sizeof(unsigned short))
  312 
  313         if (!inode->i_blksize) {
  314                 blocks = (tmp.st_size + BLOCK_SIZE - 1) >> BLOCK_SIZE_BITS;
  315                 if (blocks > D_B) {
  316                         indirect = (blocks - D_B + I_B - 1) / I_B;
  317                         blocks += indirect;
  318                         if (indirect > 1) {
  319                                 indirect = (indirect - 1 + I_B - 1) / I_B;
  320                                 blocks += indirect;
  321                                 if (indirect > 1)
  322                                         blocks++;
  323                         }
  324                 }
  325                 tmp.st_blocks = (BLOCK_SIZE / 512) * blocks;
  326                 tmp.st_blksize = BLOCK_SIZE;
  327         } else {
  328                 tmp.st_blocks = inode->i_blocks;
  329                 tmp.st_blksize = inode->i_blksize;
  330         }
  331         return copy_to_user(statbuf,&tmp,sizeof(tmp)) ? -EFAULT : 0;
  332 }
  333 
  334 asmlinkage long sys_stat64(char * filename, struct stat64 * statbuf, long flags)
  335 {
  336         struct nameidata nd;
  337         int error;
  338 
  339         error = user_path_walk(filename, &nd);
  340         if (!error) {
  341                 error = do_revalidate(nd.dentry);
  342                 if (!error)
  343                         error = cp_new_stat64(nd.dentry->d_inode, statbuf);
  344                 path_release(&nd);
  345         }
  346         return error;
  347 }
  348 
  349 asmlinkage long sys_lstat64(char * filename, struct stat64 * statbuf, long flags)
  350 {
  351         struct nameidata nd;
  352         int error;
  353 
  354         error = user_path_walk_link(filename, &nd);
  355         if (!error) {
  356                 error = do_revalidate(nd.dentry);
  357                 if (!error)
  358                         error = cp_new_stat64(nd.dentry->d_inode, statbuf);
  359                 path_release(&nd);
  360         }
  361         return error;
  362 }
  363 
  364 asmlinkage long sys_fstat64(unsigned long fd, struct stat64 * statbuf, long flags)
  365 {
  366         struct file * f;
  367         int err = -EBADF;
  368 
  369         f = fget(fd);
  370         if (f) {
  371                 struct dentry * dentry = f->f_dentry;
  372 
  373                 err = do_revalidate(dentry);
  374                 if (!err)
  375                         err = cp_new_stat64(dentry->d_inode, statbuf);
  376                 fput(f);
  377         }
  378         return err;
  379 }
  380 
  381 #endif /* LFS-64 */

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