fs/udf/symlink.c

   1 /*
   2  * symlink.c
   3  *
   4  * PURPOSE
   5  *      Symlink handling routines for the OSTA-UDF(tm) filesystem.
   6  *
   7  * CONTACTS
   8  *      E-mail regarding any portion of the Linux UDF file system should be
   9  *      directed to the development team mailing list (run by majordomo):
  10  *              linux_udf@hootie.lvld.hp.com
  11  *
  12  * COPYRIGHT
  13  *      This file is distributed under the terms of the GNU General Public
  14  *      License (GPL). Copies of the GPL can be obtained from:
  15  *              ftp://prep.ai.mit.edu/pub/gnu/GPL
  16  *      Each contributing author retains all rights to their own work.
  17  *
  18  *  (C) 1998-2000 Ben Fennema
  19  *  (C) 1999 Stelias Computing Inc
  20  *
  21  * HISTORY
  22  *
  23  *  04/16/99 blf  Created.
  24  *
  25  */
  26
  27 #include "udfdecl.h"
  28 #include <asm/uaccess.h>
  29 #include <linux/errno.h>
  30 #include <linux/fs.h>
  31 #include <linux/udf_fs.h>
  32 #include <linux/sched.h>
  33 #include <linux/mm.h>
  34 #include <linux/stat.h>
  35 #include <linux/malloc.h>
  36 #include <linux/pagemap.h>
  37 #include "udf_i.h"
  38
  39 static void udf_pc_to_char(char *from, int fromlen, char *to)
  40 {
  41         struct PathComponent *pc;
  42         int elen = 0;
  43         char *p = to;
  44
  45         while (elen < fromlen)
  46         {
  47                 pc = (struct PathComponent *)(from + elen);
  48                 switch (pc->componentType)
  49                 {
  50                         case 1:
  51                                 if (pc->lengthComponentIdent == 0)
  52                                 {
  53                                         p = to;
  54                                         *p++ = '/';
  55                                 }
  56                                 break;
  57                         case 3:
  58                                 memcpy(p, "../", 3);
  59                                 p += 3;
  60                                 break;
  61                         case 4:
  62                                 memcpy(p, "./", 2);
  63                                 p += 2;
  64                                 /* that would be . - just ignore */
  65                                 break;
  66                         case 5:
  67                                 memcpy(p, pc->componentIdent, pc->lengthComponentIdent);
  68                                 p += pc->lengthComponentIdent;
  69                                 *p++ = '/';
  70                 }
  71                 elen += sizeof(struct PathComponent) + pc->lengthComponentIdent;
  72         }
  73         if (p > to+1)
  74                 p[-1] = '\0';
  75         else
  76                 p[0] = '\0';
  77 }
  78
  79 static int udf_symlink_filler(struct file *file, struct page *page)
  80 {
  81         struct inode *inode = (struct inode*)page->mapping->host;
  82         struct buffer_head *bh = NULL;
  83         char *symlink;
  84         int err = -EIO;
  85         char *p = (char *)kmap(page);
  86
  87         if (UDF_I_ALLOCTYPE(inode) == ICB_FLAG_AD_IN_ICB)
  88         {
  89                 bh = udf_tread(inode->i_sb, inode->i_ino, inode->i_sb->s_blocksize);
  90
  91                 if (!bh)
  92                         goto out;
  93
  94                 symlink = bh->b_data + udf_file_entry_alloc_offset(inode);
  95         }
  96         else
  97         {
  98                 bh = bread(inode->i_dev, udf_block_map(inode, 0),
  99                                 inode->i_sb->s_blocksize);
 100
 101                 if (!bh)
 102                         goto out;
 103
 104                 symlink = bh->b_data;
 105         }
 106
 107         udf_pc_to_char(symlink, inode->i_size, p);
 108         udf_release_data(bh);
 109
 110         SetPageUptodate(page);
 111         kunmap(page);
 112         UnlockPage(page);
 113         return 0;
 114 out:
 115         SetPageError(page);
 116         kunmap(page);
 117         UnlockPage(page);
 118         return err;
 119 }
 120
 121 /*
 122  * symlinks can't do much...
 123  */
 124 struct address_space_operations udf_symlink_aops = {
 125         readpage:                       udf_symlink_filler,
 126 };