source: src/router/busybox/e2fsprogs/ext2fs/rw_bitmaps.c @ 8864

/* vi: set sw=4 ts=4: */
/*
 * rw_bitmaps.c --- routines to read and write the  inode and block bitmaps.
 *
 * Copyright (C) 1993, 1994, 1994, 1996 Theodore Ts'o.
 *
 * %Begin-Header%
 * This file may be redistributed under the terms of the GNU Public
 * License.
 * %End-Header%
 */

#include <stdio.h>
#include <string.h>
#if HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <fcntl.h>
#include <time.h>
#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif
#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif

#include "ext2_fs.h"
#include "ext2fs.h"
#include "e2image.h"

#if defined(__powerpc__) && BB_BIG_ENDIAN
/*
 * On the PowerPC, the big-endian variant of the ext2 filesystem
 * has its bitmaps stored as 32-bit words with bit 0 as the LSB
 * of each word.  Thus a bitmap with only bit 0 set would be, as
 * a string of bytes, 00 00 00 01 00 ...
 * To cope with this, we byte-reverse each word of a bitmap if
 * we have a big-endian filesystem, that is, if we are *not*
 * byte-swapping other word-sized numbers.
 */
#define EXT2_BIG_ENDIAN_BITMAPS
#endif

#ifdef EXT2_BIG_ENDIAN_BITMAPS
static void ext2fs_swap_bitmap(ext2_filsys fs, char *bitmap, int nbytes)
{
        __u32 *p = (__u32 *) bitmap;
        int n;

        for (n = nbytes / sizeof(__u32); n > 0; --n, ++p)
                *p = ext2fs_swab32(*p);
}
#endif

errcode_t ext2fs_write_inode_bitmap(ext2_filsys fs)
{
        dgrp_t          i;
        size_t          nbytes;
        errcode_t       retval;
        char * inode_bitmap = fs->inode_map->bitmap;
        char * bitmap_block = NULL;
        blk_t           blk;

        EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

        if (!(fs->flags & EXT2_FLAG_RW))
                return EXT2_ET_RO_FILSYS;
        if (!inode_bitmap)
                return 0;
        nbytes = (size_t) ((EXT2_INODES_PER_GROUP(fs->super)+7) / 8);

        retval = ext2fs_get_mem(fs->blocksize, &bitmap_block);
        if (retval)
                return retval;
        memset(bitmap_block, 0xff, fs->blocksize);
        for (i = 0; i < fs->group_desc_count; i++) {
                memcpy(bitmap_block, inode_bitmap, nbytes);
                blk = fs->group_desc[i].bg_inode_bitmap;
                if (blk) {
#ifdef EXT2_BIG_ENDIAN_BITMAPS
                        if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
                              (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)))
                                ext2fs_swap_bitmap(fs, bitmap_block, nbytes);
#endif
                        retval = io_channel_write_blk(fs->io, blk, 1,
                                                      bitmap_block);
                        if (retval)
                                return EXT2_ET_INODE_BITMAP_WRITE;
                }
                inode_bitmap += nbytes;
        }
        fs->flags &= ~EXT2_FLAG_IB_DIRTY;
        ext2fs_free_mem(&bitmap_block);
        return 0;
}

errcode_t ext2fs_write_block_bitmap (ext2_filsys fs)
{
        dgrp_t          i;
        unsigned int    j;
        int             nbytes;
        unsigned int    nbits;
        errcode_t       retval;
        char * block_bitmap = fs->block_map->bitmap;
        char * bitmap_block = NULL;
        blk_t           blk;

        EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

        if (!(fs->flags & EXT2_FLAG_RW))
                return EXT2_ET_RO_FILSYS;
        if (!block_bitmap)
                return 0;
        nbytes = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
        retval = ext2fs_get_mem(fs->blocksize, &bitmap_block);
        if (retval)
                return retval;
        memset(bitmap_block, 0xff, fs->blocksize);
        for (i = 0; i < fs->group_desc_count; i++) {
                memcpy(bitmap_block, block_bitmap, nbytes);
                if (i == fs->group_desc_count - 1) {
                        /* Force bitmap padding for the last group */
                        nbits = ((fs->super->s_blocks_count
                                  - fs->super->s_first_data_block)
                                 % EXT2_BLOCKS_PER_GROUP(fs->super));
                        if (nbits)
                                for (j = nbits; j < fs->blocksize * 8; j++)
                                        ext2fs_set_bit(j, bitmap_block);
                }
                blk = fs->group_desc[i].bg_block_bitmap;
                if (blk) {
#ifdef EXT2_BIG_ENDIAN_BITMAPS
                        if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
                              (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)))
                                ext2fs_swap_bitmap(fs, bitmap_block, nbytes);
#endif
                        retval = io_channel_write_blk(fs->io, blk, 1,
                                                      bitmap_block);
                        if (retval)
                                return EXT2_ET_BLOCK_BITMAP_WRITE;
                }
                block_bitmap += nbytes;
        }
        fs->flags &= ~EXT2_FLAG_BB_DIRTY;
        ext2fs_free_mem(&bitmap_block);
        return 0;
}

static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block)
{
        dgrp_t i;
        char *block_bitmap = 0, *inode_bitmap = 0;
        char *buf;
        errcode_t retval;
        int block_nbytes = (int) EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
        int inode_nbytes = (int) EXT2_INODES_PER_GROUP(fs->super) / 8;
        blk_t   blk;

        EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

        fs->write_bitmaps = ext2fs_write_bitmaps;

        retval = ext2fs_get_mem(strlen(fs->device_name) + 80, &buf);
        if (retval)
                return retval;
        if (do_block) {
                ext2fs_free_block_bitmap(fs->block_map);
                sprintf(buf, "block bitmap for %s", fs->device_name);
                retval = ext2fs_allocate_block_bitmap(fs, buf, &fs->block_map);
                if (retval)
                        goto cleanup;
                block_bitmap = fs->block_map->bitmap;
        }
        if (do_inode) {
                ext2fs_free_inode_bitmap(fs->inode_map);
                sprintf(buf, "inode bitmap for %s", fs->device_name);
                retval = ext2fs_allocate_inode_bitmap(fs, buf, &fs->inode_map);
                if (retval)
                        goto cleanup;
                inode_bitmap = fs->inode_map->bitmap;
        }
        ext2fs_free_mem(&buf);

        if (fs->flags & EXT2_FLAG_IMAGE_FILE) {
                if (inode_bitmap) {
                        blk = (fs->image_header->offset_inodemap /
                               fs->blocksize);
                        retval = io_channel_read_blk(fs->image_io, blk,
                             -(inode_nbytes * fs->group_desc_count),
                             inode_bitmap);
                        if (retval)
                                goto cleanup;
                }
                if (block_bitmap) {
                        blk = (fs->image_header->offset_blockmap /
                               fs->blocksize);
                        retval = io_channel_read_blk(fs->image_io, blk,
                             -(block_nbytes * fs->group_desc_count),
                             block_bitmap);
                        if (retval)
                                goto cleanup;
                }
                return 0;
        }

        for (i = 0; i < fs->group_desc_count; i++) {
                if (block_bitmap) {
                        blk = fs->group_desc[i].bg_block_bitmap;
                        if (blk) {
                                retval = io_channel_read_blk(fs->io, blk,
                                             -block_nbytes, block_bitmap);
                                if (retval) {
                                        retval = EXT2_ET_BLOCK_BITMAP_READ;
                                        goto cleanup;
                                }
#ifdef EXT2_BIG_ENDIAN_BITMAPS
                                if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
                                      (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
                                        ext2fs_swap_bitmap(fs, block_bitmap, block_nbytes);
#endif
                        } else
                                memset(block_bitmap, 0, block_nbytes);
                        block_bitmap += block_nbytes;
                }
                if (inode_bitmap) {
                        blk = fs->group_desc[i].bg_inode_bitmap;
                        if (blk) {
                                retval = io_channel_read_blk(fs->io, blk,
                                             -inode_nbytes, inode_bitmap);
                                if (retval) {
                                        retval = EXT2_ET_INODE_BITMAP_READ;
                                        goto cleanup;
                                }
#ifdef EXT2_BIG_ENDIAN_BITMAPS
                                if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
                                      (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
                                        ext2fs_swap_bitmap(fs, inode_bitmap, inode_nbytes);
#endif
                        } else
                                memset(inode_bitmap, 0, inode_nbytes);
                        inode_bitmap += inode_nbytes;
                }
        }
        return 0;

cleanup:
        if (do_block) {
                ext2fs_free_mem(&fs->block_map);
        }
        if (do_inode) {
                ext2fs_free_mem(&fs->inode_map);
        }
        ext2fs_free_mem(&buf);
        return retval;
}

errcode_t ext2fs_read_inode_bitmap (ext2_filsys fs)
{
        return read_bitmaps(fs, 1, 0);
}

errcode_t ext2fs_read_block_bitmap(ext2_filsys fs)
{
        return read_bitmaps(fs, 0, 1);
}

errcode_t ext2fs_read_bitmaps(ext2_filsys fs)
{

        EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

        if (fs->inode_map && fs->block_map)
                return 0;

        return read_bitmaps(fs, !fs->inode_map, !fs->block_map);
}

errcode_t ext2fs_write_bitmaps(ext2_filsys fs)
{
        errcode_t       retval;

        EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);

        if (fs->block_map && ext2fs_test_bb_dirty(fs)) {
                retval = ext2fs_write_block_bitmap(fs);
                if (retval)
                        return retval;
        }
        if (fs->inode_map && ext2fs_test_ib_dirty(fs)) {
                retval = ext2fs_write_inode_bitmap(fs);
                if (retval)
                        return retval;
        }
        return 0;
}