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@hpesjro.fc.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) 1998-2001 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/time.h>
  33 #include <linux/mm.h>
  34 #include <linux/stat.h>
  35 #include <linux/slab.h>
  36 #include <linux/pagemap.h>
  37 #include <linux/smp_lock.h>
  38 #include <linux/buffer_head.h>
  39 #include "udf_i.h"
  40
  41 static void udf_pc_to_char(struct super_block *sb, char *from, int fromlen, char *to)
  42 {
  43         struct pathComponent *pc;
  44         int elen = 0;
  45         char *p = to;
  46
  47         while (elen < fromlen)
  48         {
  49                 pc = (struct pathComponent *)(from + elen);
  50                 switch (pc->componentType)
  51                 {
  52                         case 1:
  53                                 if (pc->lengthComponentIdent == 0)
  54                                 {
  55                                         p = to;
  56                                         *p++ = '/';
  57                                 }
  58                                 break;
  59                         case 3:
  60                                 memcpy(p, "../", 3);
  61                                 p += 3;
  62                                 break;
  63                         case 4:
  64                                 memcpy(p, "./", 2);
  65                                 p += 2;
  66                                 /* that would be . - just ignore */
  67                                 break;
  68                         case 5:
  69                                 p += udf_get_filename(sb, pc->componentIdent, p, pc->lengthComponentIdent);
  70                                 *p++ = '/';
  71                                 break;
  72                 }
  73                 elen += sizeof(struct pathComponent) + pc->lengthComponentIdent;
  74         }
  75         if (p > to+1)
  76                 p[-1] = '\0';
  77         else
  78                 p[0] = '\0';
  79 }
  80
  81 static int udf_symlink_filler(struct file *file, struct page *page)
  82 {
  83         struct inode *inode = page->mapping->host;
  84         struct buffer_head *bh = NULL;
  85         char *symlink;
  86         int err = -EIO;
  87         char *p = kmap(page);
  88
  89         lock_kernel();
  90         if (UDF_I_ALLOCTYPE(inode) == ICBTAG_FLAG_AD_IN_ICB)
  91                 symlink = UDF_I_DATA(inode) + UDF_I_LENEATTR(inode);
  92         else
  93         {
  94                 bh = sb_bread(inode->i_sb, udf_block_map(inode, 0));
  95
  96                 if (!bh)
  97                         goto out;
  98
  99                 symlink = bh->b_data;
 100         }
 101
 102         udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p);
 103         udf_release_data(bh);
 104
 105         unlock_kernel();
 106         SetPageUptodate(page);
 107         kunmap(page);
 108         unlock_page(page);
 109         return 0;
 110 out:
 111         unlock_kernel();
 112         SetPageError(page);
 113         kunmap(page);
 114         unlock_page(page);
 115         return err;
 116 }
 117
 118 /*
 119  * symlinks can't do much...
 120  */
 121 struct address_space_operations udf_symlink_aops = {
 122         .readpage               = udf_symlink_filler,
 123 };