lib/ext2fs/dblist.c

/*
 * dblist.c -- directory block list functions
 *
 * Copyright 1997 by Theodore Ts'o
 *
 * %Begin-Header%
 * This file may be redistributed under the terms of the GNU Public
 * License.
 * %End-Header%
 *
 */

#include <stdio.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <string.h>
#include <time.h>

#include "ext2_fs.h"
#include "ext2fsP.h"

static EXT2_QSORT_TYPE dir_block_cmp(const void *a, const void *b);

/*
 * Returns the number of directories in the filesystem as reported by
 * the group descriptors.  Of course, the group descriptors could be
 * wrong!
 */
errcode_t ext2fs_get_num_dirs(ext2_filsys fs, ext2_ino_t *ret_num_dirs)
{
	dgrp_t	i;
	ext2_ino_t	num_dirs, max_dirs;

	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

	num_dirs = 0;
	max_dirs = fs->super->s_inodes_per_group;
	for (i = 0; i < fs->group_desc_count; i++) {
		if (fs->group_desc[i].bg_used_dirs_count > max_dirs)
			num_dirs += max_dirs / 8;
		else
			num_dirs += fs->group_desc[i].bg_used_dirs_count;
	}
	if (num_dirs > fs->super->s_inodes_count)
		num_dirs = fs->super->s_inodes_count;

	*ret_num_dirs = num_dirs;

	return 0;
}

/*
 * helper function for making a new directory block list (for
 * initialize and copy).
 */
static errcode_t make_dblist(ext2_filsys fs, ext2_ino_t size, ext2_ino_t count,
			     struct ext2_db_entry *list,
			     ext2_dblist *ret_dblist)
{
	ext2_dblist	dblist;
	errcode_t	retval;
	size_t		len;

	EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

	if ((ret_dblist == 0) && fs->dblist &&
	    (fs->dblist->magic == EXT2_ET_MAGIC_DBLIST))
		return 0;

	retval = ext2fs_get_mem(sizeof(struct ext2_struct_dblist), &dblist);
	if (retval)
		return retval;
	memset(dblist, 0, sizeof(struct ext2_struct_dblist));

	dblist->magic = EXT2_ET_MAGIC_DBLIST;
	dblist->fs = fs;
	if (size)
		dblist->size = size;
	else {
		retval = ext2fs_get_num_dirs(fs, &dblist->size);
		if (retval)
			goto cleanup;
		dblist->size = (dblist->size * 2) + 12;
	}
	len = (size_t) sizeof(struct ext2_db_entry) * dblist->size;
	dblist->count = count;
	retval = ext2fs_get_array(dblist->size, sizeof(struct ext2_db_entry),
		&dblist->list);
	if (retval)
		goto cleanup;

	if (list)
		memcpy(dblist->list, list, len);
	else
		memset(dblist->list, 0, len);
	if (ret_dblist)
		*ret_dblist = dblist;
	else
		fs->dblist = dblist;
	return 0;
cleanup:
	if (dblist)
		ext2fs_free_mem(&dblist);
	return retval;
}

/*
 * Initialize a directory block list
 */
errcode_t ext2fs_init_dblist(ext2_filsys fs, ext2_dblist *ret_dblist)
{
	ext2_dblist	dblist;
	errcode_t	retval;

	retval = make_dblist(fs, 0, 0, 0, &dblist);
	if (retval)
		return retval;

	dblist->sorted = 1;
	if (ret_dblist)
		*ret_dblist = dblist;
	else
		fs->dblist = dblist;

	return 0;
}

/*
 * Copy a directory block list
 */
errcode_t ext2fs_copy_dblist(ext2_dblist src, ext2_dblist *dest)
{
	ext2_dblist	dblist;
	errcode_t	retval;

	retval = make_dblist(src->fs, src->size, src->count, src->list,
			     &dblist);
	if (retval)
		return retval;
	dblist->sorted = src->sorted;
	*dest = dblist;
	return 0;
}

/*
 * Close a directory block list
 *
 * (moved to closefs.c)
 */


/*
 * Add a directory block to the directory block list
 */
errcode_t ext2fs_add_dir_block(ext2_dblist dblist, ext2_ino_t ino, blk_t blk,
			       int blockcnt)
{
	struct ext2_db_entry 	*new_entry;
	errcode_t		retval;
	unsigned long		old_size;

	EXT2_CHECK_MAGIC(dblist, EXT2_ET_MAGIC_DBLIST);

	if (dblist->count >= dblist->size) {
		old_size = dblist->size * sizeof(struct ext2_db_entry);
		dblist->size += dblist->size > 200 ? dblist->size / 2 : 100;
		retval = ext2fs_resize_mem(old_size, (size_t) dblist->size *
					   sizeof(struct ext2_db_entry),
					   &dblist->list);
		if (retval) {
			dblist->size -= 100;
			return retval;
		}
	}
	new_entry = dblist->list + ( (int) dblist->count++);
	new_entry->blk = blk;
	new_entry->ino = ino;
	new_entry->blockcnt = blockcnt;

	dblist->sorted = 0;

	return 0;
}

/*
 * Change the directory block to the directory block list
 */
errcode_t ext2fs_set_dir_block(ext2_dblist dblist, ext2_ino_t ino, blk_t blk,
			       int blockcnt)
{
	dgrp_t			i;

	EXT2_CHECK_MAGIC(dblist, EXT2_ET_MAGIC_DBLIST);

	for (i=0; i < dblist->count; i++) {
		if ((dblist->list[i].ino != ino) ||
		    (dblist->list[i].blockcnt != blockcnt))
			continue;
		dblist->list[i].blk = blk;
		dblist->sorted = 0;
		return 0;
	}
	return EXT2_ET_DB_NOT_FOUND;
}

void ext2fs_dblist_sort(ext2_dblist dblist,
			EXT2_QSORT_TYPE (*sortfunc)(const void *,
						    const void *))
{
	if (!sortfunc)
		sortfunc = dir_block_cmp;
	qsort(dblist->list, (size_t) dblist->count,
	      sizeof(struct ext2_db_entry), sortfunc);
	dblist->sorted = 1;
}

/*
 * This function iterates over the directory block list
 */
errcode_t ext2fs_dblist_iterate(ext2_dblist dblist,
				int (*func)(ext2_filsys fs,
					    struct ext2_db_entry *db_info,
					    void	*priv_data),
				void *priv_data)
{
	ext2_ino_t	i;
	int		ret;

	EXT2_CHECK_MAGIC(dblist, EXT2_ET_MAGIC_DBLIST);

	if (!dblist->sorted)
		ext2fs_dblist_sort(dblist, 0);
	for (i=0; i < dblist->count; i++) {
		ret = (*func)(dblist->fs, &dblist->list[(int)i], priv_data);
		if (ret & DBLIST_ABORT)
			return 0;
	}
	return 0;
}

static EXT2_QSORT_TYPE dir_block_cmp(const void *a, const void *b)
{
	const struct ext2_db_entry *db_a =
		(const struct ext2_db_entry *) a;
	const struct ext2_db_entry *db_b =
		(const struct ext2_db_entry *) b;

	if (db_a->blk != db_b->blk)
		return (int) (db_a->blk - db_b->blk);

	if (db_a->ino != db_b->ino)
		return (int) (db_a->ino - db_b->ino);

	return (int) (db_a->blockcnt - db_b->blockcnt);
}

int ext2fs_dblist_count(ext2_dblist dblist)
{
	return (int) dblist->count;
}

errcode_t ext2fs_dblist_get_last(ext2_dblist dblist,
				 struct ext2_db_entry **entry)
{
	EXT2_CHECK_MAGIC(dblist, EXT2_ET_MAGIC_DBLIST);

	if (dblist->count == 0)
		return EXT2_ET_DBLIST_EMPTY;

	if (entry)
		*entry = dblist->list + ( (int) dblist->count-1);
	return 0;
}

errcode_t ext2fs_dblist_drop_last(ext2_dblist dblist)
{
	EXT2_CHECK_MAGIC(dblist, EXT2_ET_MAGIC_DBLIST);

	if (dblist->count == 0)
		return EXT2_ET_DBLIST_EMPTY;

	dblist->count--;
	return 0;
}