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/slab.h>
  30 #include <linux/pagemap.h>
  31 #include <linux/smp_lock.h>
  32 #include <linux/buffer_head.h>
  33 #include "udf_i.h"
  34
  35 static void udf_pc_to_char(struct super_block *sb, unsigned char *from,
  36                            int fromlen, unsigned char *to)
  37 {
  38         struct pathComponent *pc;
  39         int elen = 0;
  40         unsigned char *p = to;
  41
  42         while (elen < fromlen) {
  43                 pc = (struct pathComponent *)(from + elen);
  44                 switch (pc->componentType) {
  45                 case 1:
  46                         if (pc->lengthComponentIdent == 0) {
  47                                 p = to;
  48                                 *p++ = '/';
  49                         }
  50                         break;
  51                 case 3:
  52                         memcpy(p, "../", 3);
  53                         p += 3;
  54                         break;
  55                 case 4:
  56                         memcpy(p, "./", 2);
  57                         p += 2;
  58                         /* that would be . - just ignore */
  59                         break;
  60                 case 5:
  61                         p += udf_get_filename(sb, pc->componentIdent, p,
  62                                               pc->lengthComponentIdent);
  63                         *p++ = '/';
  64                         break;
  65                 }
  66                 elen += sizeof(struct pathComponent) + pc->lengthComponentIdent;
  67         }
  68         if (p > to + 1)
  69                 p[-1] = '\0';
  70         else
  71                 p[0] = '\0';
  72 }
  73
  74 static int udf_symlink_filler(struct file *file, struct page *page)
  75 {
  76         struct inode *inode = page->mapping->host;
  77         struct buffer_head *bh = NULL;
  78         unsigned char *symlink;
  79         int err = -EIO;
  80         unsigned char *p = kmap(page);
  81         struct udf_inode_info *iinfo;
  82
  83         lock_kernel();
  84         iinfo = UDF_I(inode);
  85         if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
  86                 symlink = iinfo->i_ext.i_data + iinfo->i_lenEAttr;
  87         } else {
  88                 bh = sb_bread(inode->i_sb, udf_block_map(inode, 0));
  89
  90                 if (!bh)
  91                         goto out;
  92
  93                 symlink = bh->b_data;
  94         }
  95
  96         udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p);
  97         brelse(bh);
  98
  99         unlock_kernel();
 100         SetPageUptodate(page);
 101         kunmap(page);
 102         unlock_page(page);
 103         return 0;
 104
 105 out:
 106         unlock_kernel();
 107         SetPageError(page);
 108         kunmap(page);
 109         unlock_page(page);
 110         return err;
 111 }
 112
 113 /*
 114  * symlinks can't do much...
 115  */
 116 const struct address_space_operations udf_symlink_aops = {
 117         .readpage               = udf_symlink_filler,
 118 };