LXR linux/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/buffer_head.h>
  31#include "udf_i.h"
  32
  33static void udf_pc_to_char(struct super_block *sb, unsigned char *from,
  34                           int fromlen, unsigned char *to)
  35{
  36        struct pathComponent *pc;
  37        int elen = 0;
  38        unsigned char *p = to;
  39
  40        while (elen < fromlen) {
  41                pc = (struct pathComponent *)(from + elen);
  42                switch (pc->componentType) {
  43                case 1:
  44                        if (pc->lengthComponentIdent == 0) {
  45                                p = to;
  46                                *p++ = '/';
  47                        }
  48                        break;
  49                case 3:
  50                        memcpy(p, "../", 3);
  51                        p += 3;
  52                        break;
  53                case 4:
  54                        memcpy(p, "./", 2);
  55                        p += 2;
  56                        /* that would be . - just ignore */
  57                        break;
  58                case 5:
  59                        p += udf_get_filename(sb, pc->componentIdent, p,
  60                                              pc->lengthComponentIdent);
  61                        *p++ = '/';
  62                        break;
  63                }
  64                elen += sizeof(struct pathComponent) + pc->lengthComponentIdent;
  65        }
  66        if (p > to + 1)
  67                p[-1] = '\0';
  68        else
  69                p[0] = '\0';
  70}
  71
  72static int udf_symlink_filler(struct file *file, struct page *page)
  73{
  74        struct inode *inode = page->mapping->host;
  75        struct buffer_head *bh = NULL;
  76        unsigned char *symlink;
  77        int err = -EIO;
  78        unsigned char *p = kmap(page);
  79        struct udf_inode_info *iinfo;
  80        uint32_t pos;
  81
  82        iinfo = UDF_I(inode);
  83        pos = udf_block_map(inode, 0);
  84
  85        down_read(&iinfo->i_data_sem);
  86        if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
  87                symlink = iinfo->i_ext.i_data + iinfo->i_lenEAttr;
  88        } else {
  89                bh = sb_bread(inode->i_sb, pos);
  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        brelse(bh);
  99
 100        up_read(&iinfo->i_data_sem);
 101        SetPageUptodate(page);
 102        kunmap(page);
 103        unlock_page(page);
 104        return 0;
 105
 106out:
 107        up_read(&iinfo->i_data_sem);
 108        SetPageError(page);
 109        kunmap(page);
 110        unlock_page(page);
 111        return err;
 112}
 113
 114/*
 115 * symlinks can't do much...
 116 */
 117const struct address_space_operations udf_symlink_aops = {
 118        .readpage               = udf_symlink_filler,
 119};
 120