[3320] | 1 | /* vi: set sw=4 ts=4: */
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| 2 | /*
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| 3 | * rw_bitmaps.c --- routines to read and write the inode and block bitmaps.
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| 4 | *
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| 5 | * Copyright (C) 1993, 1994, 1994, 1996 Theodore Ts'o.
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| 6 | *
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| 7 | * %Begin-Header%
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| 8 | * This file may be redistributed under the terms of the GNU Public
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| 9 | * License.
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| 10 | * %End-Header%
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| 11 | */
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| 12 |
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| 13 | #include <stdio.h>
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| 14 | #include <string.h>
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| 15 | #if HAVE_UNISTD_H
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| 16 | #include <unistd.h>
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| 17 | #endif
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| 18 | #include <fcntl.h>
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| 19 | #include <time.h>
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| 20 | #ifdef HAVE_SYS_STAT_H
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| 21 | #include <sys/stat.h>
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| 22 | #endif
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| 23 | #ifdef HAVE_SYS_TYPES_H
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| 24 | #include <sys/types.h>
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| 25 | #endif
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| 26 |
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| 27 | #include "ext2_fs.h"
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| 28 | #include "ext2fs.h"
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| 29 | #include "e2image.h"
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| 30 |
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| 31 | #if defined(__powerpc__) && BB_BIG_ENDIAN
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| 32 | /*
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| 33 | * On the PowerPC, the big-endian variant of the ext2 filesystem
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| 34 | * has its bitmaps stored as 32-bit words with bit 0 as the LSB
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| 35 | * of each word. Thus a bitmap with only bit 0 set would be, as
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| 36 | * a string of bytes, 00 00 00 01 00 ...
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| 37 | * To cope with this, we byte-reverse each word of a bitmap if
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| 38 | * we have a big-endian filesystem, that is, if we are *not*
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| 39 | * byte-swapping other word-sized numbers.
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| 40 | */
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| 41 | #define EXT2_BIG_ENDIAN_BITMAPS
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| 42 | #endif
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| 43 |
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| 44 | #ifdef EXT2_BIG_ENDIAN_BITMAPS
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| 45 | static void ext2fs_swap_bitmap(ext2_filsys fs, char *bitmap, int nbytes)
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| 46 | {
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| 47 | __u32 *p = (__u32 *) bitmap;
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| 48 | int n;
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| 49 |
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| 50 | for (n = nbytes / sizeof(__u32); n > 0; --n, ++p)
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| 51 | *p = ext2fs_swab32(*p);
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| 52 | }
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| 53 | #endif
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| 54 |
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| 55 | errcode_t ext2fs_write_inode_bitmap(ext2_filsys fs)
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| 56 | {
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| 57 | dgrp_t i;
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| 58 | size_t nbytes;
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| 59 | errcode_t retval;
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| 60 | char * inode_bitmap = fs->inode_map->bitmap;
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| 61 | char * bitmap_block = NULL;
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| 62 | blk_t blk;
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| 63 |
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| 64 | EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
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| 65 |
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| 66 | if (!(fs->flags & EXT2_FLAG_RW))
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| 67 | return EXT2_ET_RO_FILSYS;
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| 68 | if (!inode_bitmap)
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| 69 | return 0;
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| 70 | nbytes = (size_t) ((EXT2_INODES_PER_GROUP(fs->super)+7) / 8);
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| 71 |
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| 72 | retval = ext2fs_get_mem(fs->blocksize, &bitmap_block);
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| 73 | if (retval)
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| 74 | return retval;
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| 75 | memset(bitmap_block, 0xff, fs->blocksize);
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| 76 | for (i = 0; i < fs->group_desc_count; i++) {
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| 77 | memcpy(bitmap_block, inode_bitmap, nbytes);
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| 78 | blk = fs->group_desc[i].bg_inode_bitmap;
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| 79 | if (blk) {
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| 80 | #ifdef EXT2_BIG_ENDIAN_BITMAPS
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| 81 | if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
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| 82 | (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)))
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| 83 | ext2fs_swap_bitmap(fs, bitmap_block, nbytes);
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| 84 | #endif
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| 85 | retval = io_channel_write_blk(fs->io, blk, 1,
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| 86 | bitmap_block);
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| 87 | if (retval)
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| 88 | return EXT2_ET_INODE_BITMAP_WRITE;
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| 89 | }
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| 90 | inode_bitmap += nbytes;
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| 91 | }
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| 92 | fs->flags &= ~EXT2_FLAG_IB_DIRTY;
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| 93 | ext2fs_free_mem(&bitmap_block);
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| 94 | return 0;
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| 95 | }
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| 96 |
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| 97 | errcode_t ext2fs_write_block_bitmap (ext2_filsys fs)
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| 98 | {
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| 99 | dgrp_t i;
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| 100 | unsigned int j;
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| 101 | int nbytes;
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| 102 | unsigned int nbits;
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| 103 | errcode_t retval;
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| 104 | char * block_bitmap = fs->block_map->bitmap;
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| 105 | char * bitmap_block = NULL;
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| 106 | blk_t blk;
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| 107 |
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| 108 | EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
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| 109 |
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| 110 | if (!(fs->flags & EXT2_FLAG_RW))
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| 111 | return EXT2_ET_RO_FILSYS;
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| 112 | if (!block_bitmap)
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| 113 | return 0;
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| 114 | nbytes = EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
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| 115 | retval = ext2fs_get_mem(fs->blocksize, &bitmap_block);
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| 116 | if (retval)
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| 117 | return retval;
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| 118 | memset(bitmap_block, 0xff, fs->blocksize);
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| 119 | for (i = 0; i < fs->group_desc_count; i++) {
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| 120 | memcpy(bitmap_block, block_bitmap, nbytes);
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| 121 | if (i == fs->group_desc_count - 1) {
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| 122 | /* Force bitmap padding for the last group */
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| 123 | nbits = ((fs->super->s_blocks_count
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| 124 | - fs->super->s_first_data_block)
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| 125 | % EXT2_BLOCKS_PER_GROUP(fs->super));
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| 126 | if (nbits)
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| 127 | for (j = nbits; j < fs->blocksize * 8; j++)
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| 128 | ext2fs_set_bit(j, bitmap_block);
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| 129 | }
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| 130 | blk = fs->group_desc[i].bg_block_bitmap;
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| 131 | if (blk) {
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| 132 | #ifdef EXT2_BIG_ENDIAN_BITMAPS
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| 133 | if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
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| 134 | (fs->flags & EXT2_FLAG_SWAP_BYTES_WRITE)))
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| 135 | ext2fs_swap_bitmap(fs, bitmap_block, nbytes);
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| 136 | #endif
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| 137 | retval = io_channel_write_blk(fs->io, blk, 1,
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| 138 | bitmap_block);
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| 139 | if (retval)
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| 140 | return EXT2_ET_BLOCK_BITMAP_WRITE;
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| 141 | }
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| 142 | block_bitmap += nbytes;
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| 143 | }
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| 144 | fs->flags &= ~EXT2_FLAG_BB_DIRTY;
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| 145 | ext2fs_free_mem(&bitmap_block);
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| 146 | return 0;
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| 147 | }
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| 148 |
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| 149 | static errcode_t read_bitmaps(ext2_filsys fs, int do_inode, int do_block)
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| 150 | {
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| 151 | dgrp_t i;
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| 152 | char *block_bitmap = NULL, *inode_bitmap = NULL;
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| 153 | char *buf;
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| 154 | errcode_t retval;
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| 155 | int block_nbytes = (int) EXT2_BLOCKS_PER_GROUP(fs->super) / 8;
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| 156 | int inode_nbytes = (int) EXT2_INODES_PER_GROUP(fs->super) / 8;
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| 157 | blk_t blk;
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| 158 |
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| 159 | EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
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| 160 |
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| 161 | fs->write_bitmaps = ext2fs_write_bitmaps;
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| 162 |
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| 163 | retval = ext2fs_get_mem(strlen(fs->device_name) + 80, &buf);
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| 164 | if (retval)
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| 165 | return retval;
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| 166 | if (do_block) {
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| 167 | ext2fs_free_block_bitmap(fs->block_map);
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| 168 | sprintf(buf, "block bitmap for %s", fs->device_name);
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| 169 | retval = ext2fs_allocate_block_bitmap(fs, buf, &fs->block_map);
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| 170 | if (retval)
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| 171 | goto cleanup;
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| 172 | block_bitmap = fs->block_map->bitmap;
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| 173 | }
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| 174 | if (do_inode) {
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| 175 | ext2fs_free_inode_bitmap(fs->inode_map);
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| 176 | sprintf(buf, "inode bitmap for %s", fs->device_name);
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| 177 | retval = ext2fs_allocate_inode_bitmap(fs, buf, &fs->inode_map);
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| 178 | if (retval)
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| 179 | goto cleanup;
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| 180 | inode_bitmap = fs->inode_map->bitmap;
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| 181 | }
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| 182 | ext2fs_free_mem(&buf);
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| 183 |
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| 184 | if (fs->flags & EXT2_FLAG_IMAGE_FILE) {
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| 185 | if (inode_bitmap) {
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| 186 | blk = (fs->image_header->offset_inodemap /
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| 187 | fs->blocksize);
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| 188 | retval = io_channel_read_blk(fs->image_io, blk,
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| 189 | -(inode_nbytes * fs->group_desc_count),
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| 190 | inode_bitmap);
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| 191 | if (retval)
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| 192 | goto cleanup;
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| 193 | }
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| 194 | if (block_bitmap) {
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| 195 | blk = (fs->image_header->offset_blockmap /
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| 196 | fs->blocksize);
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| 197 | retval = io_channel_read_blk(fs->image_io, blk,
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| 198 | -(block_nbytes * fs->group_desc_count),
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| 199 | block_bitmap);
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| 200 | if (retval)
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| 201 | goto cleanup;
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| 202 | }
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| 203 | return 0;
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| 204 | }
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| 205 |
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| 206 | for (i = 0; i < fs->group_desc_count; i++) {
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| 207 | if (block_bitmap) {
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| 208 | blk = fs->group_desc[i].bg_block_bitmap;
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| 209 | if (blk) {
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| 210 | retval = io_channel_read_blk(fs->io, blk,
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| 211 | -block_nbytes, block_bitmap);
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| 212 | if (retval) {
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| 213 | retval = EXT2_ET_BLOCK_BITMAP_READ;
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| 214 | goto cleanup;
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| 215 | }
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| 216 | #ifdef EXT2_BIG_ENDIAN_BITMAPS
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| 217 | if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
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| 218 | (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
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| 219 | ext2fs_swap_bitmap(fs, block_bitmap, block_nbytes);
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| 220 | #endif
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| 221 | } else
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| 222 | memset(block_bitmap, 0, block_nbytes);
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| 223 | block_bitmap += block_nbytes;
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| 224 | }
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| 225 | if (inode_bitmap) {
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| 226 | blk = fs->group_desc[i].bg_inode_bitmap;
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| 227 | if (blk) {
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| 228 | retval = io_channel_read_blk(fs->io, blk,
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| 229 | -inode_nbytes, inode_bitmap);
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| 230 | if (retval) {
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| 231 | retval = EXT2_ET_INODE_BITMAP_READ;
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| 232 | goto cleanup;
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| 233 | }
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| 234 | #ifdef EXT2_BIG_ENDIAN_BITMAPS
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| 235 | if (!((fs->flags & EXT2_FLAG_SWAP_BYTES) ||
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| 236 | (fs->flags & EXT2_FLAG_SWAP_BYTES_READ)))
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| 237 | ext2fs_swap_bitmap(fs, inode_bitmap, inode_nbytes);
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| 238 | #endif
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| 239 | } else
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| 240 | memset(inode_bitmap, 0, inode_nbytes);
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| 241 | inode_bitmap += inode_nbytes;
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| 242 | }
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| 243 | }
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| 244 | return 0;
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| 245 |
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| 246 | cleanup:
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| 247 | if (do_block) {
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| 248 | ext2fs_free_mem(&fs->block_map);
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| 249 | }
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| 250 | if (do_inode) {
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| 251 | ext2fs_free_mem(&fs->inode_map);
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| 252 | }
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| 253 | ext2fs_free_mem(&buf);
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| 254 | return retval;
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| 255 | }
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| 256 |
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| 257 | errcode_t ext2fs_read_inode_bitmap (ext2_filsys fs)
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| 258 | {
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| 259 | return read_bitmaps(fs, 1, 0);
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| 260 | }
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| 261 |
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| 262 | errcode_t ext2fs_read_block_bitmap(ext2_filsys fs)
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| 263 | {
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| 264 | return read_bitmaps(fs, 0, 1);
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| 265 | }
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| 266 |
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| 267 | errcode_t ext2fs_read_bitmaps(ext2_filsys fs)
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| 268 | {
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| 269 | EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
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| 270 |
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| 271 | if (fs->inode_map && fs->block_map)
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| 272 | return 0;
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| 273 |
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| 274 | return read_bitmaps(fs, !fs->inode_map, !fs->block_map);
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| 275 | }
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| 276 |
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| 277 | errcode_t ext2fs_write_bitmaps(ext2_filsys fs)
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| 278 | {
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| 279 | errcode_t retval;
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| 280 |
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| 281 | EXT2_CHECK_MAGIC(fs, EXT2_ET_MAGIC_EXT2FS_FILSYS);
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| 282 |
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| 283 | if (fs->block_map && ext2fs_test_bb_dirty(fs)) {
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| 284 | retval = ext2fs_write_block_bitmap(fs);
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| 285 | if (retval)
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| 286 | return retval;
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| 287 | }
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| 288 | if (fs->inode_map && ext2fs_test_ib_dirty(fs)) {
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| 289 | retval = ext2fs_write_inode_bitmap(fs);
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| 290 | if (retval)
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| 291 | return retval;
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| 292 | }
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| 293 | return 0;
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| 294 | }
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