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/udf_fs.h>
  27 #include <linux/time.h>
  28 #include <linux/mm.h>
  29 #include <linux/stat.h>
  30 #include <linux/slab.h>
  31 #include <linux/pagemap.h>
  32 #include <linux/smp_lock.h>
  33 #include <linux/buffer_head.h>
  34 #include "udf_i.h"
  35
  36 static void udf_pc_to_char(struct super_block *sb, char *from, int fromlen, char *to)
  37 {
  38         struct pathComponent *pc;
  39         int elen = 0;
  40         char *p = to;
  41
  42         while (elen < fromlen)
  43         {
  44                 pc = (struct pathComponent *)(from + elen);
  45                 switch (pc->componentType)
  46                 {
  47                         case 1:
  48                                 if (pc->lengthComponentIdent == 0)
  49                                 {
  50                                         p = to;
  51                                         *p++ = '/';
  52                                 }
  53                                 break;
  54                         case 3:
  55                                 memcpy(p, "../", 3);
  56                                 p += 3;
  57                                 break;
  58                         case 4:
  59                                 memcpy(p, "./", 2);
  60                                 p += 2;
  61                                 /* that would be . - just ignore */
  62                                 break;
  63                         case 5:
  64                                 p += udf_get_filename(sb, pc->componentIdent, p, pc->lengthComponentIdent);
  65                                 *p++ = '/';
  66                                 break;
  67                 }
  68                 elen += sizeof(struct pathComponent) + pc->lengthComponentIdent;
  69         }
  70         if (p > to+1)
  71                 p[-1] = '\0';
  72         else
  73                 p[0] = '\0';
  74 }
  75
  76 static int udf_symlink_filler(struct file *file, struct page *page)
  77 {
  78         struct inode *inode = page->mapping->host;
  79         struct buffer_head *bh = NULL;
  80         char *symlink;
  81         int err = -EIO;
  82         char *p = kmap(page);
  83
  84         lock_kernel();
  85         if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_IN_ICB)
  86                 symlink = UDF_I_DATA(inode) + UDF_I_LENEATTR(inode);
  87         else
  88         {
  89                 bh = sb_bread(inode->i_sb, udf_block_map(inode, 0));
  90
  91                 if (!bh)
  92                         goto out;
  93
  94                 symlink = bh->b_data;
  95         }
  96
  97         udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p);
  98         udf_release_data(bh);
  99
 100         unlock_kernel();
 101         SetPageUptodate(page);
 102         kunmap(page);
 103         unlock_page(page);
 104         return 0;
 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 };