fs/ncpfs/symlink.c

   1 /*
   2  *  linux/fs/ncpfs/symlink.c
   3  *
   4  *  Code for allowing symbolic links on NCPFS (i.e. NetWare)
   5  *  Symbolic links are not supported on native NetWare, so we use an
   6  *  infrequently-used flag (Sh) and store a two-word magic header in
   7  *  the file to make sure we don't accidentally use a non-link file
   8  *  as a link.
   9  *
  10  *  When using the NFS namespace, we set the mode to indicate a symlink and
  11  *  don't bother with the magic numbers.
  12  *
  13  *  from linux/fs/ext2/symlink.c
  14  *
  15  *  Copyright (C) 1998-99, Frank A. Vorstenbosch
  16  *
  17  *  ncpfs symlink handling code
  18  *  NLS support (c) 1999 Petr Vandrovec
  19  *  Modified 2000 Ben Harris, University of Cambridge for NFS NS meta-info
  20  *
  21  */
  22
  23
  24 #include <asm/uaccess.h>
  25
  26 #include <linux/errno.h>
  27 #include <linux/fs.h>
  28 #include <linux/ncp_fs.h>
  29 #include <linux/time.h>
  30 #include <linux/mm.h>
  31 #include <linux/stat.h>
  32 #include "ncplib_kernel.h"
  33
  34
  35 /* these magic numbers must appear in the symlink file -- this makes it a bit
  36    more resilient against the magic attributes being set on random files. */
  37
  38 #define NCP_SYMLINK_MAGIC0      cpu_to_le32(0x6c6d7973)     /* "symlnk->" */
  39 #define NCP_SYMLINK_MAGIC1      cpu_to_le32(0x3e2d6b6e)
  40
  41 /* ----- read a symbolic link ------------------------------------------ */
  42
  43 static int ncp_symlink_readpage(struct file *file, struct page *page)
  44 {
  45         struct inode *inode = page->mapping->host;
  46         int error, length, len;
  47         char *link, *rawlink;
  48         char *buf = kmap(page);
  49
  50         error = -ENOMEM;
  51         rawlink=(char *)kmalloc(NCP_MAX_SYMLINK_SIZE, GFP_KERNEL);
  52         if (!rawlink)
  53                 goto fail;
  54
  55         if (ncp_make_open(inode,O_RDONLY))
  56                 goto failEIO;
  57
  58         error=ncp_read_kernel(NCP_SERVER(inode),NCP_FINFO(inode)->file_handle,
  59                          0,NCP_MAX_SYMLINK_SIZE,rawlink,&length);
  60
  61         ncp_inode_close(inode);
  62         /* Close file handle if no other users... */
  63         ncp_make_closed(inode);
  64         if (error)
  65                 goto failEIO;
  66
  67         if (NCP_FINFO(inode)->flags & NCPI_KLUDGE_SYMLINK) {
  68                 if (length<NCP_MIN_SYMLINK_SIZE ||
  69                     ((__le32 *)rawlink)[0]!=NCP_SYMLINK_MAGIC0 ||
  70                     ((__le32 *)rawlink)[1]!=NCP_SYMLINK_MAGIC1)
  71                         goto failEIO;
  72                 link = rawlink + 8;
  73                 length -= 8;
  74         } else {
  75                 link = rawlink;
  76         }
  77
  78         len = NCP_MAX_SYMLINK_SIZE;
  79         error = ncp_vol2io(NCP_SERVER(inode), buf, &len, link, length, 0);
  80         kfree(rawlink);
  81         if (error)
  82                 goto fail;
  83         SetPageUptodate(page);
  84         kunmap(page);
  85         unlock_page(page);
  86         return 0;
  87
  88 failEIO:
  89         error = -EIO;
  90         kfree(rawlink);
  91 fail:
  92         SetPageError(page);
  93         kunmap(page);
  94         unlock_page(page);
  95         return error;
  96 }
  97
  98 /*
  99  * symlinks can't do much...
 100  */
 101 const struct address_space_operations ncp_symlink_aops = {
 102         .readpage       = ncp_symlink_readpage,
 103 };
 104
 105 /* ----- create a new symbolic link -------------------------------------- */
 106
 107 int ncp_symlink(struct inode *dir, struct dentry *dentry, const char *symname) {
 108         struct inode *inode;
 109         char *rawlink;
 110         int length, err, i, outlen;
 111         int kludge;
 112         int mode;
 113         __le32 attr;
 114         unsigned int hdr;
 115
 116         DPRINTK("ncp_symlink(dir=%p,dentry=%p,symname=%s)\n",dir,dentry,symname);
 117
 118         if (ncp_is_nfs_extras(NCP_SERVER(dir), NCP_FINFO(dir)->volNumber))
 119                 kludge = 0;
 120         else
 121 #ifdef CONFIG_NCPFS_EXTRAS
 122         if (NCP_SERVER(dir)->m.flags & NCP_MOUNT_SYMLINKS)
 123                 kludge = 1;
 124         else
 125 #endif
 126         /* EPERM is returned by VFS if symlink procedure does not exist */
 127                 return -EPERM;
 128
 129         rawlink=(char *)kmalloc(NCP_MAX_SYMLINK_SIZE, GFP_KERNEL);
 130         if (!rawlink)
 131                 return -ENOMEM;
 132
 133         if (kludge) {
 134                 mode = 0;
 135                 attr = aSHARED | aHIDDEN;
 136                 ((__le32 *)rawlink)[0]=NCP_SYMLINK_MAGIC0;
 137                 ((__le32 *)rawlink)[1]=NCP_SYMLINK_MAGIC1;
 138                 hdr = 8;
 139         } else {
 140                 mode = S_IFLNK | S_IRWXUGO;
 141                 attr = 0;
 142                 hdr = 0;
 143         }
 144
 145         length = strlen(symname);
 146         /* map to/from server charset, do not touch upper/lower case as
 147            symlink can point out of ncp filesystem */
 148         outlen = NCP_MAX_SYMLINK_SIZE - hdr;
 149         err = ncp_io2vol(NCP_SERVER(dir), rawlink + hdr, &outlen, symname, length, 0);
 150         if (err)
 151                 goto failfree;
 152
 153         outlen += hdr;
 154
 155         err = -EIO;
 156         if (ncp_create_new(dir,dentry,mode,0,attr)) {
 157                 goto failfree;
 158         }
 159
 160         inode=dentry->d_inode;
 161
 162         if (ncp_make_open(inode, O_WRONLY))
 163                 goto failfree;
 164
 165         if (ncp_write_kernel(NCP_SERVER(inode), NCP_FINFO(inode)->file_handle,
 166                              0, outlen, rawlink, &i) || i!=outlen) {
 167                 goto fail;
 168         }
 169
 170         ncp_inode_close(inode);
 171         ncp_make_closed(inode);
 172         kfree(rawlink);
 173         return 0;
 174 fail:;
 175         ncp_inode_close(inode);
 176         ncp_make_closed(inode);
 177 failfree:;
 178         kfree(rawlink);
 179         return err;
 180 }
 181
 182 /* ----- EOF ----- */