source: mainline/uspace/lib/ext4/libext4_directory.c@ bf66ef4

/*
 * 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       Ext4 directory structure operations.
 */

#include <byteorder.h>
#include <errno.h>
#include <malloc.h>
#include <string.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);
}

void ext4_directory_entry_ll_set_inode(ext4_directory_entry_ll_t *de,
                uint32_t inode)
{
        de->inode = host2uint32_t_le(inode);
}

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

void ext4_directory_entry_ll_set_entry_length(ext4_directory_entry_ll_t *de,
                uint16_t length)
{
        de->entry_length = host2uint16_t_le(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;

}

void ext4_directory_entry_ll_set_name_length(ext4_superblock_t *sb,
                ext4_directory_entry_ll_t *de, uint16_t length)
{
        de->name_length = (length << 8) >> 8;

        if (ext4_superblock_get_rev_level(sb) == 0 &&
                    ext4_superblock_get_minor_rev_level(sb) < 5) {

                de->name_length_high = length >> 8;
        }
}


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;
                }

                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;
}


int ext4_directory_find_entry(ext4_directory_iterator_t *it,
                ext4_inode_ref_t *parent, const char *name)
{
        int rc;
        uint32_t name_size = strlen(name);

        // Index search
        if (ext4_superblock_has_feature_compatible(it->fs->superblock, EXT4_FEATURE_COMPAT_DIR_INDEX) &&
                        ext4_inode_has_flag(parent->inode, EXT4_INODE_FLAG_INDEX)) {

                rc = ext4_directory_dx_find_entry(it, it->fs, parent, name_size, name);

                // Check if index is not corrupted
                if (rc != EXT4_ERR_BAD_DX_DIR) {

                        if (rc != EOK) {
                                return rc;
                        }
                        return EOK;
                }

                EXT4FS_DBG("index is corrupted - doing linear search");
        }

        bool found = false;
        // Linear search
        while (it->current != NULL) {
                uint32_t inode = ext4_directory_entry_ll_get_inode(it->current);

                /* ignore empty directory entries */
                if (inode != 0) {
                        uint16_t entry_name_size = ext4_directory_entry_ll_get_name_length(
                                        it->fs->superblock, it->current);

                        if (entry_name_size == name_size && bcmp(name, it->current->name,
                                    name_size) == 0) {
                                found = true;
                                break;
                        }
                }

                rc = ext4_directory_iterator_next(it);
                if (rc != EOK) {
                        return rc;
                }
        }

        if (!found) {
                return ENOENT;
        }

        return EOK;
}


int ext4_directory_remove_entry(ext4_filesystem_t* fs,
                ext4_inode_ref_t *parent, const char *name)
{
        int rc;
        ext4_directory_iterator_t it;

        if (!ext4_inode_is_type(fs->superblock, parent->inode,
            EXT4_INODE_MODE_DIRECTORY)) {
                return ENOTDIR;
        }

        rc = ext4_directory_iterator_init(&it, fs, parent, 0);
        if (rc != EOK) {
                return rc;
        }

        rc = ext4_directory_find_entry(&it, parent, name);
        if (rc != EOK) {
                ext4_directory_iterator_fini(&it);
                return rc;
        }

        if (rc != EOK) {
                ext4_directory_iterator_fini(&it);
                return rc;
        }

        // TODO modify HTREE index if exists

        uint32_t block_size = ext4_superblock_get_block_size(fs->superblock);
        uint32_t pos = it.current_offset % block_size;

        ext4_directory_entry_ll_set_inode(it.current, 0);

        if (pos != 0) {
                uint32_t offset = 0;

                ext4_directory_entry_ll_t *tmp_dentry = it.current_block->data;
                uint16_t tmp_dentry_length =
                                ext4_directory_entry_ll_get_entry_length(tmp_dentry);

                while ((offset + tmp_dentry_length) < pos) {
                        offset += ext4_directory_entry_ll_get_entry_length(tmp_dentry);
                        tmp_dentry = it.current_block->data + offset;
                        tmp_dentry_length =
                                        ext4_directory_entry_ll_get_entry_length(tmp_dentry);
                }

                assert(tmp_dentry_length + offset == pos);

                uint16_t del_entry_length =
                                ext4_directory_entry_ll_get_entry_length(it.current);
                ext4_directory_entry_ll_set_entry_length(tmp_dentry,
                                tmp_dentry_length + del_entry_length);

        }


        it.current_block->dirty = true;

        ext4_directory_iterator_fini(&it);
        return EOK;
}


/**
 * @}
 */