source: mainline/uspace/lib/ext4/libext4_directory.c@ e68c834

/*
 * Copyright (c) 2011 Frantisek Princ
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 *   notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright
 *   notice, this list of conditions and the following disclaimer in the
 *   documentation and/or other materials provided with the distribution.
 * - The name of the author may not be used to endorse or promote products
 *   derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/** @addtogroup libext4
 * @{
 */ 

/**
 * @file        libext4_directory.c
 * @brief       TODO
 */

#include <byteorder.h>
#include <errno.h>
#include "libext4.h"

static int ext4_directory_iterator_set(ext4_directory_iterator_t *,
    uint32_t);


uint32_t ext4_directory_entry_ll_get_inode(ext4_directory_entry_ll_t *de)
{
        return uint32_t_le2host(de->inode);
}

uint16_t ext4_directory_entry_ll_get_entry_length(
    ext4_directory_entry_ll_t *de)
{
        return uint16_t_le2host(de->entry_length);
}

uint16_t ext4_directory_entry_ll_get_name_length(
    ext4_superblock_t *sb, ext4_directory_entry_ll_t *de)
{
        if (ext4_superblock_get_rev_level(sb) == 0 &&
            ext4_superblock_get_minor_rev_level(sb) < 5) {
                return ((uint16_t)de->name_length_high) << 8 |
                    ((uint16_t)de->name_length);
        }
        return de->name_length;
}

int ext4_directory_iterator_init(ext4_directory_iterator_t *it,
    ext4_filesystem_t *fs, ext4_inode_ref_t *inode_ref, aoff64_t pos)
{
        it->inode_ref = inode_ref;
        it->fs = fs;
        it->current = NULL;
        it->current_offset = 0;
        it->current_block = NULL;

        return ext4_directory_iterator_seek(it, pos);
}


int ext4_directory_iterator_next(ext4_directory_iterator_t *it)
{
        uint16_t skip;

        assert(it->current != NULL);

        skip = ext4_directory_entry_ll_get_entry_length(it->current);

        return ext4_directory_iterator_seek(it, it->current_offset + skip);
}


int ext4_directory_iterator_seek(ext4_directory_iterator_t *it, aoff64_t pos)
{
        int rc;

        uint64_t size;
        aoff64_t current_block_idx;
        aoff64_t next_block_idx;
        uint32_t next_block_phys_idx;
        uint32_t block_size;

        size = ext4_inode_get_size(it->fs->superblock, it->inode_ref->inode);

        /* The iterator is not valid until we seek to the desired position */
        it->current = NULL;

        /* Are we at the end? */
        if (pos >= size) {
                if (it->current_block) {
                        rc = block_put(it->current_block);
                        it->current_block = NULL;
                        if (rc != EOK) {
                                return rc;
                        }
                }

                it->current_offset = pos;
                return EOK;
        }

        block_size = ext4_superblock_get_block_size(it->fs->superblock);
        current_block_idx = it->current_offset / block_size;
        next_block_idx = pos / block_size;

        /* If we don't have a block or are moving accross block boundary,
         * we need to get another block
         */
        if (it->current_block == NULL || current_block_idx != next_block_idx) {
                if (it->current_block) {
                        rc = block_put(it->current_block);
                        it->current_block = NULL;
                        if (rc != EOK) {
                                return rc;
                        }
                }

                rc = ext4_filesystem_get_inode_data_block_index(it->fs,
                    it->inode_ref->inode, next_block_idx, &next_block_phys_idx);
                if (rc != EOK) {
                        return rc;
                }

                EXT4FS_DBG("next_block_phys_idx: \%d", next_block_phys_idx);

                rc = block_get(&it->current_block, it->fs->device, next_block_phys_idx,
                    BLOCK_FLAGS_NONE);
                if (rc != EOK) {
                        it->current_block = NULL;
                        return rc;
                }
        }

        it->current_offset = pos;

        return ext4_directory_iterator_set(it, block_size);
}

static int ext4_directory_iterator_set(ext4_directory_iterator_t *it,
    uint32_t block_size)
{
        uint32_t offset_in_block = it->current_offset % block_size;

        it->current = NULL;

        /* Ensure proper alignment */
        if ((offset_in_block % 4) != 0) {
                return EIO;
        }

        /* Ensure that the core of the entry does not overflow the block */
        if (offset_in_block > block_size - 8) {
                return EIO;
        }

        ext4_directory_entry_ll_t *entry = it->current_block->data + offset_in_block;

        /* Ensure that the whole entry does not overflow the block */
        uint16_t length = ext4_directory_entry_ll_get_entry_length(entry);
        if (offset_in_block + length > block_size) {
                return EIO;
        }

        /* Ensure the name length is not too large */
        if (ext4_directory_entry_ll_get_name_length(it->fs->superblock,
            entry) > length-8) {
                return EIO;
        }

        it->current = entry;
        return EOK;
}


int ext4_directory_iterator_fini(ext4_directory_iterator_t *it)
{
        int rc;

        it->fs = NULL;
        it->inode_ref = NULL;
        it->current = NULL;

        if (it->current_block) {
                rc = block_put(it->current_block);
                if (rc != EOK) {
                        return rc;
                }
        }

        return EOK;
}


/**
 * @}
 */