root/fs/nfs/symlink.c

/* */

DEFINITIONS

1. nfs_follow_link
2. nfs_readlink

   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/segment.h>
  20 
  21 static int nfs_readlink(struct inode *, char *, int);
  22 static int nfs_follow_link(struct inode *, struct inode *, int, int,
  23                            struct inode **);
  24 
  25 /*
  26  * symlinks can't do much...
  27  */
  28 struct inode_operations nfs_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         nfs_readlink,           /* readlink */
  40         nfs_follow_link,        /* follow_link */
  41         NULL,                   /* bmap */
  42         NULL,                   /* truncate */
  43         NULL                    /* permission */
  44 };
  45 
  46 static int nfs_follow_link(struct inode *dir, struct inode *inode,
     /*  */
  47                            int flag, int mode, struct inode **res_inode)
  48 {
  49         int error, *mem;
  50         unsigned int len;
  51         char *res, *res2;
  52 
  53         *res_inode = NULL;
  54         if (!dir) {
  55                 dir = current->fs->root;
  56                 dir->i_count++;
  57         }
  58         if (!inode) {
  59                 iput(dir);
  60                 return -ENOENT;
  61         }
  62         if (!S_ISLNK(inode->i_mode)) {
  63                 iput(dir);
  64                 *res_inode = inode;
  65                 return 0;
  66         }
  67         if (current->link_count > 5) {
  68                 iput(inode);
  69                 iput(dir);
  70                 return -ELOOP;
  71         }
  72         error = nfs_proc_readlink(NFS_SERVER(inode), NFS_FH(inode), &mem,
  73                 &res, &len, NFS_MAXPATHLEN);
  74         if (error) {
  75                 iput(inode);
  76                 iput(dir);
  77                 kfree(mem);
  78                 return error;
  79         }
  80         while ((res2 = (char *) kmalloc(NFS_MAXPATHLEN + 1, GFP_NFS)) == NULL) {
  81                 schedule();
  82         }
  83         memcpy(res2, res, len);
  84         res2[len] = '\0';
  85         kfree(mem);
  86         iput(inode);
  87         current->link_count++;
  88         error = open_namei(res2, flag, mode, res_inode, dir);
  89         current->link_count--;
  90         kfree_s(res2, NFS_MAXPATHLEN + 1);
  91         return error;
  92 }
  93 
  94 static int nfs_readlink(struct inode *inode, char *buffer, int buflen)
     /*  */
  95 {
  96         int error, *mem;
  97         unsigned int len;
  98         char *res;
  99 
 100         if (!S_ISLNK(inode->i_mode)) {
 101                 iput(inode);
 102                 return -EINVAL;
 103         }
 104         if (buflen > NFS_MAXPATHLEN)
 105                 buflen = NFS_MAXPATHLEN;
 106         error = nfs_proc_readlink(NFS_SERVER(inode), NFS_FH(inode), &mem,
 107                 &res, &len, buflen);
 108         iput(inode);
 109         if (! error) {
 110                 memcpy_tofs(buffer, res, len);
 111                 put_user('\0', buffer + len);
 112                 error = len;
 113         }
 114         kfree(mem);
 115         return error;
 116 }

/* */