fs/isofs/symlink.c

   1 /*
   2  *  linux/fs/isofs/symlink.c
   3  *
   4  *  (C) 1992  Eric Youngdale Modified for ISO 9660 filesystem.
   5  *
   6  *  Copyright (C) 1991, 1992  Linus Torvalds
   7  *
   8  *  isofs symlink handling code.  This is only used with the Rock Ridge
   9  *  extensions to iso9660
  10  */
  11
  12 #include <linux/string.h>
  13 #include <linux/errno.h>
  14 #include <linux/sched.h>
  15 #include <linux/fs.h>
  16 #include <linux/iso_fs.h>
  17 #include <linux/stat.h>
  18 #include <linux/malloc.h>
  19
  20 #include <asm/uaccess.h>
  21
  22 static int isofs_readlink(struct dentry *, char *, int);
  23 static struct dentry * isofs_follow_link(struct dentry *, struct dentry *, unsigned int);
  24
  25 /*
  26  * symlinks can't do much...
  27  */
  28 struct inode_operations isofs_symlink_inode_operations = {
  29         NULL,                   /* no file-operations */
  30         NULL,                   /* create */
  31         NULL,                   /* lookup */
  32         NULL,                   /* link */
  33         NULL,                   /* unlink */
  34         NULL,                   /* symlink */
  35         NULL,                   /* mkdir */
  36         NULL,                   /* rmdir */
  37         NULL,                   /* mknod */
  38         NULL,                   /* rename */
  39         isofs_readlink,         /* readlink */
  40         isofs_follow_link,      /* follow_link */
  41         NULL,                   /* readpage */
  42         NULL,                   /* writepage */
  43         NULL,                   /* bmap */
  44         NULL,                   /* truncate */
  45         NULL                    /* permission */
  46 };
  47
  48 static int isofs_readlink(struct dentry * dentry, char * buffer, int buflen)
  49 {
  50         char * pnt;
  51         int i;
  52
  53         if (buflen > 1023)
  54                 buflen = 1023;
  55         pnt = get_rock_ridge_symlink(dentry->d_inode);
  56
  57         if (!pnt)
  58                 return 0;
  59
  60         i = strlen(pnt);
  61         if (i > buflen)
  62                 i = buflen;
  63         if (copy_to_user(buffer, pnt, i))
  64                 i = -EFAULT;
  65         kfree(pnt);
  66         return i;
  67 }
  68
  69 static struct dentry * isofs_follow_link(struct dentry * dentry,
  70                                         struct dentry *base,
  71                                         unsigned int follow)
  72 {
  73         char * pnt;
  74
  75         pnt = get_rock_ridge_symlink(dentry->d_inode);
  76         if(!pnt) {
  77                 dput(base);
  78                 return ERR_PTR(-ELOOP);
  79         }
  80
  81         base = lookup_dentry(pnt, base, follow);
  82
  83         kfree(pnt);
  84         return base;
  85 }