fs/udf/symlink.c

   1 /*
   2  * symlink.c
   3  *
   4  * PURPOSE
   5  *      Symlink handling routines for the OSTA-UDF(tm) filesystem.
   6  *
   7  * COPYRIGHT
   8  *      This file is distributed under the terms of the GNU General Public
   9  *      License (GPL). Copies of the GPL can be obtained from:
  10  *              ftp://prep.ai.mit.edu/pub/gnu/GPL
  11  *      Each contributing author retains all rights to their own work.
  12  *
  13  *  (C) 1998-2001 Ben Fennema
  14  *  (C) 1999 Stelias Computing Inc
  15  *
  16  * HISTORY
  17  *
  18  *  04/16/99 blf  Created.
  19  *
  20  */
  21
  22 #include "udfdecl.h"
  23 #include <asm/uaccess.h>
  24 #include <linux/errno.h>
  25 #include <linux/fs.h>
  26 #include <linux/time.h>
  27 #include <linux/mm.h>
  28 #include <linux/stat.h>
  29 #include <linux/pagemap.h>
  30 #include <linux/smp_lock.h>
  31 #include <linux/buffer_head.h>
  32 #include "udf_i.h"
  33
  34 static void udf_pc_to_char(struct super_block *sb, unsigned char *from,
  35                            int fromlen, unsigned char *to)
  36 {
  37         struct pathComponent *pc;
  38         int elen = 0;
  39         unsigned char *p = to;
  40
  41         while (elen < fromlen) {
  42                 pc = (struct pathComponent *)(from + elen);
  43                 switch (pc->componentType) {
  44                 case 1:
  45                         if (pc->lengthComponentIdent == 0) {
  46                                 p = to;
  47                                 *p++ = '/';
  48                         }
  49                         break;
  50                 case 3:
  51                         memcpy(p, "../", 3);
  52                         p += 3;
  53                         break;
  54                 case 4:
  55                         memcpy(p, "./", 2);
  56                         p += 2;
  57                         /* that would be . - just ignore */
  58                         break;
  59                 case 5:
  60                         p += udf_get_filename(sb, pc->componentIdent, p,
  61                                               pc->lengthComponentIdent);
  62                         *p++ = '/';
  63                         break;
  64                 }
  65                 elen += sizeof(struct pathComponent) + pc->lengthComponentIdent;
  66         }
  67         if (p > to + 1)
  68                 p[-1] = '\0';
  69         else
  70                 p[0] = '\0';
  71 }
  72
  73 static int udf_symlink_filler(struct file *file, struct page *page)
  74 {
  75         struct inode *inode = page->mapping->host;
  76         struct buffer_head *bh = NULL;
  77         unsigned char *symlink;
  78         int err = -EIO;
  79         unsigned char *p = kmap(page);
  80         struct udf_inode_info *iinfo;
  81
  82         lock_kernel();
  83         iinfo = UDF_I(inode);
  84         if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
  85                 symlink = iinfo->i_ext.i_data + iinfo->i_lenEAttr;
  86         } else {
  87                 bh = sb_bread(inode->i_sb, udf_block_map(inode, 0));
  88
  89                 if (!bh)
  90                         goto out;
  91
  92                 symlink = bh->b_data;
  93         }
  94
  95         udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p);
  96         brelse(bh);
  97
  98         unlock_kernel();
  99         SetPageUptodate(page);
 100         kunmap(page);
 101         unlock_page(page);
 102         return 0;
 103
 104 out:
 105         unlock_kernel();
 106         SetPageError(page);
 107         kunmap(page);
 108         unlock_page(page);
 109         return err;
 110 }
 111
 112 /*
 113  * symlinks can't do much...
 114  */
 115 const struct address_space_operations udf_symlink_aops = {
 116         .readpage               = udf_symlink_filler,
 117 };