fs/nfs/symlink.c

   1 /*
   2  *  linux/fs/nfs/symlink.c
   3  *
   4  *  Copyright (C) 1992  Rick Sladkey
   5  *
   6  *  Optimization changes Copyright (C) 1994 Florian La Roche
   7  *
   8  *  nfs symlink handling code
   9  */
  10
  11 #include <linux/sched.h>
  12 #include <linux/errno.h>
  13 #include <linux/nfs_fs.h>
  14 #include <linux/stat.h>
  15 #include <linux/mm.h>
  16 #include <linux/malloc.h>
  17 #include <linux/string.h>
  18
  19 #include <asm/uaccess.h>
  20
  21 static int nfs_readlink(struct dentry *, char *, int);
  22 static struct dentry *nfs_follow_link(struct dentry *, struct dentry *, unsigned int);
  23
  24 /*
  25  * symlinks can't do much...
  26  */
  27 struct inode_operations nfs_symlink_inode_operations = {
  28         NULL,                   /* no file-operations */
  29         NULL,                   /* create */
  30         NULL,                   /* lookup */
  31         NULL,                   /* link */
  32         NULL,                   /* unlink */
  33         NULL,                   /* symlink */
  34         NULL,                   /* mkdir */
  35         NULL,                   /* rmdir */
  36         NULL,                   /* mknod */
  37         NULL,                   /* rename */
  38         nfs_readlink,           /* readlink */
  39         nfs_follow_link,        /* follow_link */
  40         NULL,                   /* readpage */
  41         NULL,                   /* writepage */
  42         NULL,                   /* bmap */
  43         NULL,                   /* truncate */
  44         NULL                    /* permission */
  45 };
  46
  47 static int nfs_readlink(struct dentry *dentry, char *buffer, int buflen)
  48 {
  49         int error;
  50         unsigned int len;
  51         char *res;
  52         void *mem;
  53
  54         dfprintk(VFS, "nfs: readlink(%s/%s)\n",
  55                 dentry->d_parent->d_name.name, dentry->d_name.name);
  56
  57         error = nfs_proc_readlink(NFS_DSERVER(dentry), NFS_FH(dentry),
  58                                         &mem, &res, &len, NFS_MAXPATHLEN);
  59         if (! error) {
  60                 if (len > buflen)
  61                         len = buflen;
  62                 copy_to_user(buffer, res, len);
  63                 error = len;
  64                 kfree(mem);
  65         }
  66         return error;
  67 }
  68
  69 static struct dentry *
  70 nfs_follow_link(struct dentry * dentry, struct dentry *base, unsigned int follow)
  71 {
  72         int error;
  73         unsigned int len;
  74         char *res;
  75         void *mem;
  76         char *path;
  77         struct dentry *result;
  78
  79         dfprintk(VFS, "nfs: follow_link(%s/%s)\n",
  80                 dentry->d_parent->d_name.name, dentry->d_name.name);
  81
  82         error = nfs_proc_readlink(NFS_DSERVER(dentry), NFS_FH(dentry),
  83                                  &mem, &res, &len, NFS_MAXPATHLEN);
  84         result = ERR_PTR(error);
  85         if (error)
  86                 goto out_dput;
  87
  88         result = ERR_PTR(-ENOMEM);
  89         path = kmalloc(len + 1, GFP_KERNEL);
  90         if (!path)
  91                 goto out_mem;
  92         memcpy(path, res, len);
  93         path[len] = 0;
  94         kfree(mem);
  95
  96         result = lookup_dentry(path, base, follow);
  97         kfree(path);
  98 out:
  99         return result;
 100
 101 out_mem:
 102         kfree(mem);
 103 out_dput:
 104         dput(base);
 105         goto out;
 106 }