source: mainline/uspace/lib/ext4/libext4_directory_index.c@ 565b6ff

/*
 * 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_index.c
 * @brief       Ext4 directory index operations.
 */

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


uint8_t ext4_directory_dx_root_info_get_hash_version(
                ext4_directory_dx_root_info_t *root_info)
{
        return root_info->hash_version;
}

void ext4_directory_dx_root_info_set_hash_version(
                ext4_directory_dx_root_info_t *root_info, uint8_t version)
{
        root_info->hash_version = version;
}

uint8_t ext4_directory_dx_root_info_get_info_length(
                ext4_directory_dx_root_info_t *root_info)
{
        return root_info->info_length;
}

void ext4_directory_dx_root_info_set_info_length(
                ext4_directory_dx_root_info_t *root_info, uint8_t info_length)
{
        root_info->info_length = info_length;
}

uint8_t ext4_directory_dx_root_info_get_indirect_levels(
                ext4_directory_dx_root_info_t *root_info)
{
        return root_info->indirect_levels;
}

void ext4_directory_dx_root_info_set_indirect_levels(
                ext4_directory_dx_root_info_t *root_info, uint8_t levels)
{
        root_info->indirect_levels = levels;
}

uint16_t ext4_directory_dx_countlimit_get_limit(
                ext4_directory_dx_countlimit_t *countlimit)
{
        return uint16_t_le2host(countlimit->limit);
}

void ext4_directory_dx_countlimit_set_limit(
                ext4_directory_dx_countlimit_t *countlimit, uint16_t limit)
{
        countlimit->limit = host2uint16_t_le(limit);
}

uint16_t ext4_directory_dx_countlimit_get_count(
                ext4_directory_dx_countlimit_t *countlimit)
{
        return uint16_t_le2host(countlimit->count);
}

void ext4_directory_dx_countlimit_set_count(
                ext4_directory_dx_countlimit_t *countlimit, uint16_t count)
{
        countlimit->count = host2uint16_t_le(count);
}

uint32_t ext4_directory_dx_entry_get_hash(ext4_directory_dx_entry_t *entry)
{
        return uint32_t_le2host(entry->hash);
}

void ext4_directory_dx_entry_set_hash(ext4_directory_dx_entry_t *entry,
                uint32_t hash)
{
        entry->hash = host2uint32_t_le(hash);
}

uint32_t ext4_directory_dx_entry_get_block(ext4_directory_dx_entry_t *entry)
{
        return uint32_t_le2host(entry->block);
}

void ext4_directory_dx_entry_set_block(ext4_directory_dx_entry_t *entry,
                uint32_t block)
{
        entry->block = host2uint32_t_le(block);
}


/**************************************************************************/


static int ext4_directory_hinfo_init(ext4_hash_info_t *hinfo, block_t *root_block,
                ext4_superblock_t *sb, size_t name_len, const char *name)
{

        ext4_directory_dx_root_t *root = (ext4_directory_dx_root_t *)root_block->data;

        if (root->info.hash_version != EXT4_HASH_VERSION_TEA &&
                        root->info.hash_version != EXT4_HASH_VERSION_HALF_MD4 &&
                        root->info.hash_version != EXT4_HASH_VERSION_LEGACY) {
                return EXT4_ERR_BAD_DX_DIR;
        }

        // Check unused flags
        if (root->info.unused_flags != 0) {
                EXT4FS_DBG("ERR: unused_flags = \%u", root->info.unused_flags);
                return EXT4_ERR_BAD_DX_DIR;
        }

        // Check indirect levels
        if (root->info.indirect_levels > 1) {
                EXT4FS_DBG("ERR: indirect_levels = \%u", root->info.indirect_levels);
                return EXT4_ERR_BAD_DX_DIR;
        }

        uint32_t block_size = ext4_superblock_get_block_size(sb);

        uint32_t entry_space = block_size;
        entry_space -= 2 * sizeof(ext4_directory_dx_dot_entry_t);
        entry_space -= sizeof(ext4_directory_dx_root_info_t);
    entry_space = entry_space / sizeof(ext4_directory_dx_entry_t);

    uint16_t limit = ext4_directory_dx_countlimit_get_limit((ext4_directory_dx_countlimit_t *)&root->entries);
    if (limit != entry_space) {
        return EXT4_ERR_BAD_DX_DIR;
        }

        hinfo->hash_version = ext4_directory_dx_root_info_get_hash_version(&root->info);
        if ((hinfo->hash_version <= EXT4_HASH_VERSION_TEA)
                        && (ext4_superblock_has_flag(sb, EXT4_SUPERBLOCK_FLAGS_UNSIGNED_HASH))) {
                // 3 is magic from ext4 linux implementation
                hinfo->hash_version += 3;
        }

        hinfo->seed = ext4_superblock_get_hash_seed(sb);

        if (name) {
                ext4_hash_string(hinfo, name_len, name);
        }

        return EOK;
}

static int ext4_directory_dx_get_leaf(ext4_hash_info_t *hinfo,
                ext4_filesystem_t *fs, ext4_inode_t *inode, block_t *root_block,
                ext4_directory_dx_block_t **dx_block, ext4_directory_dx_block_t *dx_blocks)
{
        int rc;

        ext4_directory_dx_block_t *tmp_dx_block = dx_blocks;

        ext4_directory_dx_root_t *root = (ext4_directory_dx_root_t *)root_block->data;
        ext4_directory_dx_entry_t *entries = (ext4_directory_dx_entry_t *)&root->entries;

        uint16_t limit = ext4_directory_dx_countlimit_get_limit((ext4_directory_dx_countlimit_t *)entries);
        uint8_t indirect_level = ext4_directory_dx_root_info_get_indirect_levels(&root->info);

        block_t *tmp_block = root_block;
        ext4_directory_dx_entry_t *p, *q, *m, *at;
        while (true) {

                uint16_t count = ext4_directory_dx_countlimit_get_count((ext4_directory_dx_countlimit_t *)entries);
                if ((count == 0) || (count > limit)) {
                        return EXT4_ERR_BAD_DX_DIR;
                }

                p = entries + 1;
                q = entries + count - 1;

                while (p <= q) {
                        m = p + (q - p) / 2;
                        if (ext4_directory_dx_entry_get_hash(m) > hinfo->hash) {
                                q = m - 1;
                        } else {
                                p = m + 1;
                        }
                }

                at = p - 1;

                tmp_dx_block->block = tmp_block;
                tmp_dx_block->entries = entries;
                tmp_dx_block->position = at;

        if (indirect_level == 0) {
                *dx_block = tmp_dx_block;
                return EOK;
        }

                uint32_t next_block = ext4_directory_dx_entry_get_block(at);

        indirect_level--;

        uint32_t fblock;
        rc = ext4_filesystem_get_inode_data_block_index(fs, inode, next_block, &fblock);
        if (rc != EOK) {
                return rc;
        }

        rc = block_get(&tmp_block, fs->device, fblock, BLOCK_FLAGS_NONE);
        if (rc != EOK) {
                return rc;
        }

                entries = ((ext4_directory_dx_node_t *) tmp_block->data)->entries;
                limit = ext4_directory_dx_countlimit_get_limit((ext4_directory_dx_countlimit_t *)entries);

        uint16_t entry_space = ext4_superblock_get_block_size(fs->superblock)
                        - sizeof(ext4_directory_dx_dot_entry_t);
        entry_space = entry_space / sizeof(ext4_directory_dx_entry_t);


                if (limit != entry_space) {
                        block_put(tmp_block);
                return EXT4_ERR_BAD_DX_DIR;
                }

                ++tmp_dx_block;
        }

        // Unreachable
        return EOK;
}


static int ext4_directory_dx_find_dir_entry(block_t *block,
                ext4_superblock_t *sb, size_t name_len, const char *name,
                ext4_directory_entry_ll_t **res_entry, aoff64_t *block_offset)
{

        aoff64_t offset = 0;
        ext4_directory_entry_ll_t *dentry = (ext4_directory_entry_ll_t *)block->data;
        uint8_t *addr_limit = block->data + ext4_superblock_get_block_size(sb);

        while ((uint8_t *)dentry < addr_limit) {

                if ((uint8_t*) dentry + name_len > addr_limit) {
                        break;
                }

                if (dentry->inode != 0) {
                        if (name_len == ext4_directory_entry_ll_get_name_length(sb, dentry)) {
                                // Compare names
                                if (bcmp((uint8_t *)name, dentry->name, name_len) == 0) {
                                        *block_offset = offset;
                                        *res_entry = dentry;
                                        return 1;
                                }
                        }
                }


                // Goto next entry
                uint16_t dentry_len = ext4_directory_entry_ll_get_entry_length(dentry);

        if (dentry_len == 0) {
                // TODO error
                return -1;
        }

                offset += dentry_len;
                dentry = (ext4_directory_entry_ll_t *)((uint8_t *)dentry + dentry_len);
        }

        return 0;
}

static int ext4_directory_dx_next_block(ext4_filesystem_t *fs, ext4_inode_t *inode, uint32_t hash,
                ext4_directory_dx_block_t *handle, ext4_directory_dx_block_t *handles)
{
        int rc;


    uint32_t num_handles = 0;
    ext4_directory_dx_block_t *p = handle;

    while (1) {

        p->position++;
        uint16_t count = ext4_directory_dx_countlimit_get_count((ext4_directory_dx_countlimit_t *)p->entries);

        if (p->position < p->entries + count) {
                break;
        }

        if (p == handles) {
                return 0;
        }

        num_handles++;
        p--;
    }

    uint32_t current_hash = ext4_directory_dx_entry_get_hash(p->position);

    if ((hash & 1) == 0) {
        if ((current_hash & ~1) != hash) {
                return 0;
        }
    }


    while (num_handles--) {

        uint32_t block_idx = ext4_directory_dx_entry_get_block(p->position);
        uint32_t block_addr;
        rc = ext4_filesystem_get_inode_data_block_index(fs, inode, block_idx, &block_addr);
        if (rc != EOK) {
                return rc;
        }

        block_t *block;
        rc = block_get(&block, fs->device, block_addr, BLOCK_FLAGS_NONE);
        if (rc != EOK) {
                return rc;
        }

        p++;

        block_put(p->block);
        p->block = block;
        p->entries = ((ext4_directory_dx_node_t *) block->data)->entries;
        p->position = p->entries;
    }

    return 1;

}

int ext4_directory_dx_find_entry(ext4_directory_iterator_t *it,
                ext4_filesystem_t *fs, ext4_inode_ref_t *inode_ref, size_t len, const char *name)
{
        int rc;

        // get direct block 0 (index root)
        uint32_t root_block_addr;
        rc = ext4_filesystem_get_inode_data_block_index(fs, inode_ref->inode, 0, &root_block_addr);
        if (rc != EOK) {
                return rc;
        }

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

        ext4_hash_info_t hinfo;
        rc = ext4_directory_hinfo_init(&hinfo, root_block, fs->superblock, len, name);
        if (rc != EOK) {
                block_put(root_block);
                return EXT4_ERR_BAD_DX_DIR;
        }

        // Hardcoded number 2 means maximum height of index tree !!!
        ext4_directory_dx_block_t dx_blocks[2];
        ext4_directory_dx_block_t *dx_block;
        rc = ext4_directory_dx_get_leaf(&hinfo, fs, inode_ref->inode, root_block, &dx_block, dx_blocks);
        if (rc != EOK) {
                block_put(root_block);
                return EXT4_ERR_BAD_DX_DIR;
        }


        do {

                uint32_t leaf_block_idx = ext4_directory_dx_entry_get_block(dx_block->position);
                uint32_t leaf_block_addr;
        rc = ext4_filesystem_get_inode_data_block_index(fs, inode_ref->inode, leaf_block_idx, &leaf_block_addr);
        if (rc != EOK) {
                return EXT4_ERR_BAD_DX_DIR;
        }

        block_t *leaf_block;
                rc = block_get(&leaf_block, fs->device, leaf_block_addr, BLOCK_FLAGS_NONE);
                if (rc != EOK) {
                        return EXT4_ERR_BAD_DX_DIR;
                }

                aoff64_t block_offset;
                ext4_directory_entry_ll_t *res_dentry;
                rc = ext4_directory_dx_find_dir_entry(leaf_block, fs->superblock, len, name,
                                &res_dentry, &block_offset);

                // Found => return it
                if (rc == 1) {
                        it->fs = fs;
                        it->inode_ref = inode_ref;
                        it->current_block = leaf_block;
                        it->current_offset = block_offset;
                        it->current = res_dentry;
                        return EOK;
                }

                block_put(leaf_block);

                // ERROR - corrupted index
                if (rc == -1) {
                        // TODO cleanup
                        return EXT4_ERR_BAD_DX_DIR;
                }

                rc = ext4_directory_dx_next_block(fs, inode_ref->inode, hinfo.hash, dx_block, &dx_blocks[0]);
                if (rc < 0) {
                        // TODO cleanup
                        return EXT4_ERR_BAD_DX_DIR;
                }

        } while (rc == 1);

        return ENOENT;
}

int ext4_directory_dx_add_entry(ext4_filesystem_t *fs,
                ext4_inode_ref_t *parent, size_t name_size, const char *name)
{
        // TODO delete this command
        return EXT4_ERR_BAD_DX_DIR;

        EXT4FS_DBG("NOT REACHED");

        int rc;

        // get direct block 0 (index root)
        uint32_t root_block_addr;
        rc = ext4_filesystem_get_inode_data_block_index(fs, parent->inode, 0, &root_block_addr);
        if (rc != EOK) {
                return rc;
        }

        block_t *root_block;
        rc = block_get(&root_block, fs->device, root_block_addr, BLOCK_FLAGS_NONE);
        if (rc != EOK) {
                return rc;
        }

        ext4_hash_info_t hinfo;
        rc = ext4_directory_hinfo_init(&hinfo, root_block, fs->superblock, name_size, name);
        if (rc != EOK) {
                block_put(root_block);
                return EXT4_ERR_BAD_DX_DIR;
        }

        // Hardcoded number 2 means maximum height of index tree !!!
        ext4_directory_dx_block_t dx_blocks[2];
        ext4_directory_dx_block_t *dx_block;
        rc = ext4_directory_dx_get_leaf(&hinfo, fs, parent->inode, root_block, &dx_block, dx_blocks);
        if (rc != EOK) {
                block_put(root_block);
                return EXT4_ERR_BAD_DX_DIR;
        }

        // TODO
        /*
         * 1) try to write entry
         * 2) split leaves if necessary
         * 3) return
         */


}


/**
 * @}
 */