/* vi: set sw=4 ts=4: */
/*
 * closefs.c --- close an ext2 filesystem
 *
 * Copyright (C) 1993, 1994, 1995, 1996 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 <time.h>
#include <string.h>

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

static int test_root(int a, int b)
{
        if (a == 0)
                return 1;
        while (1) {
                if (a == 1)
                        return 1;
                if (a % b)
                        return 0;
                a = a / b;
        }
}

int ext2fs_bg_has_super(ext2_filsys fs, int group_block)
{
        if (!(fs->super->s_feature_ro_compat &
              EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER))
                return 1;

        if (test_root(group_block, 3) || (test_root(group_block, 5)) ||
            test_root(group_block, 7))
                return 1;

        return 0;
}

int ext2fs_super_and_bgd_loc(ext2_filsys fs,
                             dgrp_t group,
                             blk_t *ret_super_blk,
                             blk_t *ret_old_desc_blk,
                             blk_t *ret_new_desc_blk,
                             int *ret_meta_bg)
{
        blk_t   group_block, super_blk = 0, old_desc_blk = 0, new_desc_blk = 0;
        unsigned int meta_bg, meta_bg_size;
        int     numblocks, has_super;
        int     old_desc_blocks;

        group_block = fs->super->s_first_data_block +
                (group * fs->super->s_blocks_per_group);

        if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
                old_desc_blocks = fs->super->s_first_meta_bg;
        else
                old_desc_blocks =
                        fs->desc_blocks + fs->super->s_reserved_gdt_blocks;

        if (group == fs->group_desc_count-1) {
                numblocks = (fs->super->s_blocks_count -
                             fs->super->s_first_data_block) %
                        fs->super->s_blocks_per_group;
                if (!numblocks)
                        numblocks = fs->super->s_blocks_per_group;
        } else
                numblocks = fs->super->s_blocks_per_group;

        has_super = ext2fs_bg_has_super(fs, group);

        if (has_super) {
                super_blk = group_block;
                numblocks--;
        }
        meta_bg_size = (fs->blocksize / sizeof (struct ext2_group_desc));
        meta_bg = group / meta_bg_size;

        if (!(fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG) ||
            (meta_bg < fs->super->s_first_meta_bg)) {
                if (has_super) {
                        old_desc_blk = group_block + 1;
                        numblocks -= old_desc_blocks;
                }
        } else {
                if (((group % meta_bg_size) == 0) ||
                    ((group % meta_bg_size) == 1) ||
                    ((group % meta_bg_size) == (meta_bg_size-1))) {
                        if (has_super)
                                has_super = 1;
                        new_desc_blk = group_block + has_super;
                        numblocks--;
                }
        }

        numblocks -= 2 + fs->inode_blocks_per_group;

        if (ret_super_blk)
                *ret_super_blk = super_blk;
        if (ret_old_desc_blk)
                *ret_old_desc_blk = old_desc_blk;
        if (ret_new_desc_blk)
                *ret_new_desc_blk = new_desc_blk;
        if (ret_meta_bg)
                *ret_meta_bg = meta_bg;
        return numblocks;
}


/*
 * This function forces out the primary superblock.  We need to only
 * write out those fields which we have changed, since if the
 * filesystem is mounted, it may have changed some of the other
 * fields.
 *
 * It takes as input a superblock which has already been byte swapped
 * (if necessary).
 *
 */
static errcode_t write_primary_superblock(ext2_filsys fs,
                                          struct ext2_super_block *super)
{
        __u16           *old_super, *new_super;
        int             check_idx, write_idx, size;
        errcode_t       retval;

        if (!fs->io->manager->write_byte || !fs->orig_super) {
                io_channel_set_blksize(fs->io, SUPERBLOCK_OFFSET);
                retval = io_channel_write_blk(fs->io, 1, -SUPERBLOCK_SIZE,
                                              super);
                io_channel_set_blksize(fs->io, fs->blocksize);
                return retval;
        }

        old_super = (__u16 *) fs->orig_super;
        new_super = (__u16 *) super;

        for (check_idx = 0; check_idx < SUPERBLOCK_SIZE/2; check_idx++) {
                if (old_super[check_idx] == new_super[check_idx])
                        continue;
                write_idx = check_idx;
                for (check_idx++; check_idx < SUPERBLOCK_SIZE/2; check_idx++)
                        if (old_super[check_idx] == new_super[check_idx])
                                break;
                size = 2 * (check_idx - write_idx);
                retval = io_channel_write_byte(fs->io,
                               SUPERBLOCK_OFFSET + (2 * write_idx), size,
                                               new_super + write_idx);
                if (retval)
                        return retval;
        }
        memcpy(fs->orig_super, super, SUPERBLOCK_SIZE);
        return 0;
}


/*
 * Updates the revision to EXT2_DYNAMIC_REV
 */
void ext2fs_update_dynamic_rev(ext2_filsys fs)
{
        struct ext2_super_block *sb = fs->super;

        if (sb->s_rev_level > EXT2_GOOD_OLD_REV)
                return;

        sb->s_rev_level = EXT2_DYNAMIC_REV;
        sb->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
        sb->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
        /* s_uuid is handled by e2fsck already */
        /* other fields should be left alone */
}

static errcode_t write_backup_super(ext2_filsys fs, dgrp_t group,
                                    blk_t group_block,
                                    struct ext2_super_block *super_shadow)
{
        dgrp_t  sgrp = group;

        if (sgrp > ((1 << 16) - 1))
                sgrp = (1 << 16) - 1;
#if BB_BIG_ENDIAN
        if (fs->flags & EXT2_FLAG_SWAP_BYTES)
                super_shadow->s_block_group_nr = ext2fs_swab16(sgrp);
        else
#endif
                fs->super->s_block_group_nr = sgrp;

        return io_channel_write_blk(fs->io, group_block, -SUPERBLOCK_SIZE,
                                    super_shadow);
}


errcode_t ext2fs_flush(ext2_filsys fs)
{
        dgrp_t          i;
        blk_t           group_block;
        errcode_t       retval;
        unsigned long   fs_state;
        struct ext2_super_block *super_shadow = 0;
        struct ext2_group_desc *group_shadow = 0;
        char    *group_ptr;
        int     old_desc_blocks;
#if BB_BIG_ENDIAN
        dgrp_t          j;
        struct ext2_group_desc *s, *t;
#endif

        EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

        fs_state = fs->super->s_state;

        fs->super->s_wtime = time(NULL);
        fs->super->s_block_group_nr = 0;
#if BB_BIG_ENDIAN
        if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
                retval = EXT2_ET_NO_MEMORY;
                retval = ext2fs_get_mem(SUPERBLOCK_SIZE, &super_shadow);
                if (retval)
                        goto errout;
                retval = ext2fs_get_mem((size_t)(fs->blocksize *
                                                 fs->desc_blocks),
                                        &group_shadow);
                if (retval)
                        goto errout;
                memset(group_shadow, 0, (size_t) fs->blocksize *
                       fs->desc_blocks);

                /* swap the group descriptors */
                for (j=0, s=fs->group_desc, t=group_shadow;
                     j < fs->group_desc_count; j++, t++, s++) {
                        *t = *s;
                        ext2fs_swap_group_desc(t);
                }
        } else {
                super_shadow = fs->super;
                group_shadow = fs->group_desc;
        }
#else
        super_shadow = fs->super;
        group_shadow = fs->group_desc;
#endif

        /*
         * If this is an external journal device, don't write out the
         * block group descriptors or any of the backup superblocks
         */
        if (fs->super->s_feature_incompat &
            EXT3_FEATURE_INCOMPAT_JOURNAL_DEV)
                goto write_primary_superblock_only;

        /*
         * Set the state of the FS to be non-valid.  (The state has
         * already been backed up earlier, and will be restored after
         * we write out the backup superblocks.)
         */
        fs->super->s_state &= ~EXT2_VALID_FS;
#if BB_BIG_ENDIAN
        if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
                *super_shadow = *fs->super;
                ext2fs_swap_super(super_shadow);
        }
#endif

        /*
         * Write out the master group descriptors, and the backup
         * superblocks and group descriptors.
         */
        group_block = fs->super->s_first_data_block;
        group_ptr = (char *) group_shadow;
        if (fs->super->s_feature_incompat & EXT2_FEATURE_INCOMPAT_META_BG)
                old_desc_blocks = fs->super->s_first_meta_bg;
        else
                old_desc_blocks = fs->desc_blocks;

        for (i = 0; i < fs->group_desc_count; i++) {
                blk_t   super_blk, old_desc_blk, new_desc_blk;
                int     meta_bg;

                ext2fs_super_and_bgd_loc(fs, i, &super_blk, &old_desc_blk,
                                         &new_desc_blk, &meta_bg);

                if (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) &&i && super_blk) {
                        retval = write_backup_super(fs, i, super_blk,
                                                    super_shadow);
                        if (retval)
                                goto errout;
                }
                if (fs->flags & EXT2_FLAG_SUPER_ONLY)
                        continue;
                if ((old_desc_blk) &&
                    (!(fs->flags & EXT2_FLAG_MASTER_SB_ONLY) || (i == 0))) {
                        retval = io_channel_write_blk(fs->io,
                              old_desc_blk, old_desc_blocks, group_ptr);
                        if (retval)
                                goto errout;
                }
                if (new_desc_blk) {
                        retval = io_channel_write_blk(fs->io, new_desc_blk,
                                1, group_ptr + (meta_bg*fs->blocksize));
                        if (retval)
                                goto errout;
                }
        }
        fs->super->s_block_group_nr = 0;
        fs->super->s_state = fs_state;
#if BB_BIG_ENDIAN
        if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
                *super_shadow = *fs->super;
                ext2fs_swap_super(super_shadow);
        }
#endif

        /*
         * If the write_bitmaps() function is present, call it to
         * flush the bitmaps.  This is done this way so that a simple
         * program that doesn't mess with the bitmaps doesn't need to
         * drag in the bitmaps.c code.
         */
        if (fs->write_bitmaps) {
                retval = fs->write_bitmaps(fs);
                if (retval)
                        goto errout;
        }

write_primary_superblock_only:
        /*
         * Write out master superblock.  This has to be done
         * separately, since it is located at a fixed location
         * (SUPERBLOCK_OFFSET).  We flush all other pending changes
         * out to disk first, just to avoid a race condition with an
         * insy-tinsy window....
         */
        retval = io_channel_flush(fs->io);
        retval = write_primary_superblock(fs, super_shadow);
        if (retval)
                goto errout;

        fs->flags &= ~EXT2_FLAG_DIRTY;

        retval = io_channel_flush(fs->io);
errout:
        fs->super->s_state = fs_state;
        if (fs->flags & EXT2_FLAG_SWAP_BYTES) {
                if (super_shadow)
                        ext2fs_free_mem(&super_shadow);
                if (group_shadow)
                        ext2fs_free_mem(&group_shadow);
        }
        return retval;
}

errcode_t ext2fs_close(ext2_filsys fs)
{
        errcode_t       retval;

        EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

        if (fs->flags & EXT2_FLAG_DIRTY) {
                retval = ext2fs_flush(fs);
                if (retval)
                        return retval;
        }
        if (fs->write_bitmaps) {
                retval = fs->write_bitmaps(fs);
                if (retval)
                        return retval;
        }
        ext2fs_free(fs);
        return 0;
}