root/fs/udf/symlink.c

DEFINITIONS

1. udf_pc_to_char
2. udf_symlink_filler

/*
 * symlink.c
 *
 * PURPOSE
 *      Symlink handling routines for the OSTA-UDF(tm) filesystem.
 *
 * COPYRIGHT
 *      This file is distributed under the terms of the GNU General Public
 *      License (GPL). Copies of the GPL can be obtained from:
 *              ftp://prep.ai.mit.edu/pub/gnu/GPL
 *      Each contributing author retains all rights to their own work.
 *
 *  (C) 1998-2001 Ben Fennema
 *  (C) 1999 Stelias Computing Inc
 *
 * HISTORY
 *
 *  04/16/99 blf  Created.
 *
 */

#include "udfdecl.h"
#include <asm/uaccess.h>
#include <linux/errno.h>
#include <linux/fs.h>
#include <linux/time.h>
#include <linux/mm.h>
#include <linux/stat.h>
#include <linux/slab.h>
#include <linux/pagemap.h>
#include <linux/smp_lock.h>
#include <linux/buffer_head.h>
#include "udf_i.h"

static void udf_pc_to_char(struct super_block *sb, char *from, int fromlen,
                           char *to)
{
        struct pathComponent *pc;
        int elen = 0;
        char *p = to;

        while (elen < fromlen) {
                pc = (struct pathComponent *)(from + elen);
                switch (pc->componentType) {
                case 1:
                        if (pc->lengthComponentIdent == 0) {
                                p = to;
                                *p++ = '/';
                        }
                        break;
                case 3:
                        memcpy(p, "../", 3);
                        p += 3;
                        break;
                case 4:
                        memcpy(p, "./", 2);
                        p += 2;
                        /* that would be . - just ignore */
                        break;
                case 5:
                        p += udf_get_filename(sb, pc->componentIdent, p,
                                              pc->lengthComponentIdent);
                        *p++ = '/';
                        break;
                }
                elen += sizeof(struct pathComponent) + pc->lengthComponentIdent;
        }
        if (p > to + 1)
                p[-1] = '\0';
        else
                p[0] = '\0';
}

static int udf_symlink_filler(struct file *file, struct page *page)
{
        struct inode *inode = page->mapping->host;
        struct buffer_head *bh = NULL;
        char *symlink;
        int err = -EIO;
        char *p = kmap(page);
        struct udf_inode_info *iinfo;

        lock_kernel();
        iinfo = UDF_I(inode);
        if (iinfo->i_alloc_type == ICBTAG_FLAG_AD_IN_ICB) {
                symlink = iinfo->i_ext.i_data + iinfo->i_lenEAttr;
        } else {
                bh = sb_bread(inode->i_sb, udf_block_map(inode, 0));

                if (!bh)
                        goto out;

                symlink = bh->b_data;
        }

        udf_pc_to_char(inode->i_sb, symlink, inode->i_size, p);
        brelse(bh);

        unlock_kernel();
        SetPageUptodate(page);
        kunmap(page);
        unlock_page(page);
        return 0;

out:
        unlock_kernel();
        SetPageError(page);
        kunmap(page);
        unlock_page(page);
        return err;
}

/*
 * symlinks can't do much...
 */
const struct address_space_operations udf_symlink_aops = {
        .readpage               = udf_symlink_filler,
};