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315 lines
10 KiB
315 lines
10 KiB
/*
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* Copyright (C) 2010 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "ext4_utils/ext4_utils.h"
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#include <fcntl.h>
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#include <inttypes.h>
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#include <stddef.h>
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#include <string.h>
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#include <sys/stat.h>
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#include <sys/types.h>
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#ifdef _WIN32
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#include <winsock2.h>
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#else
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#include <arpa/inet.h>
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#include <sys/ioctl.h>
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#endif
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#if defined(__linux__)
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#include <linux/fs.h>
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#elif defined(__APPLE__) && defined(__MACH__)
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#include <sys/disk.h>
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#endif
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#include "helpers.h"
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int force = 0;
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struct fs_info info;
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struct fs_aux_info aux_info;
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jmp_buf setjmp_env;
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/* returns 1 if a is a power of b */
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static int is_power_of(int a, int b) {
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while (a > b) {
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if (a % b) return 0;
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a /= b;
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}
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return (a == b) ? 1 : 0;
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}
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int bitmap_get_bit(u8* bitmap, u32 bit) {
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if (bitmap[bit / 8] & (1 << (bit % 8))) return 1;
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return 0;
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}
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void bitmap_clear_bit(u8* bitmap, u32 bit) {
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bitmap[bit / 8] &= ~(1 << (bit % 8));
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return;
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}
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/* Returns 1 if the bg contains a backup superblock. On filesystems with
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the sparse_super feature, only block groups 0, 1, and powers of 3, 5,
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and 7 have backup superblocks. Otherwise, all block groups have backup
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superblocks */
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int ext4_bg_has_super_block(int bg) {
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/* Without sparse_super, every block group has a superblock */
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if (!(info.feat_ro_compat & EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER)) return 1;
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if (bg == 0 || bg == 1) return 1;
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if (is_power_of(bg, 3) || is_power_of(bg, 5) || is_power_of(bg, 7)) return 1;
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return 0;
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}
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/* Function to read the primary superblock */
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void read_sb(int fd, struct ext4_super_block* sb) {
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off64_t ret;
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ret = lseek64(fd, 1024, SEEK_SET);
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if (ret < 0) critical_error_errno("failed to seek to superblock");
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ret = read(fd, sb, sizeof(*sb));
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if (ret < 0) critical_error_errno("failed to read superblock");
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if (ret != sizeof(*sb)) critical_error("failed to read all of superblock");
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}
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/* Compute the rest of the parameters of the filesystem from the basic info */
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void ext4_create_fs_aux_info() {
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aux_info.first_data_block = (info.block_size > 1024) ? 0 : 1;
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aux_info.len_blocks = info.len / info.block_size;
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aux_info.inode_table_blocks =
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DIV_ROUND_UP(info.inodes_per_group * info.inode_size, info.block_size);
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aux_info.groups =
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DIV_ROUND_UP(aux_info.len_blocks - aux_info.first_data_block, info.blocks_per_group);
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aux_info.blocks_per_ind = info.block_size / sizeof(u32);
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aux_info.blocks_per_dind = aux_info.blocks_per_ind * aux_info.blocks_per_ind;
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aux_info.blocks_per_tind = aux_info.blocks_per_dind * aux_info.blocks_per_dind;
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aux_info.bg_desc_blocks =
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DIV_ROUND_UP(aux_info.groups * (size_t)info.bg_desc_size, info.block_size);
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aux_info.default_i_flags = EXT4_NOATIME_FL;
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u32 last_group_size = aux_info.len_blocks == info.blocks_per_group
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? aux_info.len_blocks
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: aux_info.len_blocks % info.blocks_per_group;
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u32 last_header_size = 2 + aux_info.inode_table_blocks;
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if (ext4_bg_has_super_block((int)aux_info.groups - 1))
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last_header_size += 1 + aux_info.bg_desc_blocks + info.bg_desc_reserve_blocks;
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if (aux_info.groups <= 1 && last_group_size < last_header_size) {
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critical_error("filesystem size too small");
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}
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if (last_group_size > 0 && last_group_size < last_header_size) {
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aux_info.groups--;
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aux_info.len_blocks -= last_group_size;
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}
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/* A zero-filled superblock to be written firstly to the block
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* device to mark the file-system as invalid
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*/
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aux_info.sb_zero = (struct ext4_super_block*)calloc(1, info.block_size);
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if (!aux_info.sb_zero) critical_error_errno("calloc");
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/* The write_data* functions expect only block aligned calls.
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* This is not an issue, except when we write out the super
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* block on a system with a block size > 1K. So, we need to
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* deal with that here.
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*/
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aux_info.sb_block = (struct ext4_super_block*)calloc(1, info.block_size);
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if (!aux_info.sb_block) critical_error_errno("calloc");
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if (info.block_size > 1024)
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aux_info.sb = (struct ext4_super_block*)((char*)aux_info.sb_block + 1024);
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else
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aux_info.sb = aux_info.sb_block;
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/* Alloc an array to hold the pointers to the backup superblocks */
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aux_info.backup_sb = (struct ext4_super_block**)calloc(aux_info.groups, sizeof(char*));
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if (!aux_info.sb) critical_error_errno("calloc");
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aux_info.bg_desc =
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(struct ext2_group_desc*)calloc(aux_info.groups, sizeof(struct ext2_group_desc));
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if (!aux_info.bg_desc) critical_error_errno("calloc");
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aux_info.xattrs = NULL;
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}
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void ext4_free_fs_aux_info() {
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unsigned int i;
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for (i = 0; i < aux_info.groups; i++) {
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if (aux_info.backup_sb[i]) free(aux_info.backup_sb[i]);
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}
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free(aux_info.sb_block);
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free(aux_info.sb_zero);
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free(aux_info.bg_desc);
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}
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void ext4_parse_sb_info(struct ext4_super_block* sb) {
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if (sb->s_magic != EXT4_SUPER_MAGIC) error("superblock magic incorrect");
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if ((sb->s_state & EXT4_VALID_FS) != EXT4_VALID_FS) error("filesystem state not valid");
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ext4_parse_sb(sb, &info);
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ext4_create_fs_aux_info();
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memcpy(aux_info.sb, sb, sizeof(*sb));
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if (aux_info.first_data_block != sb->s_first_data_block)
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critical_error("first data block does not match");
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}
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u64 get_block_device_size(int fd) {
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u64 size = 0;
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int ret;
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#if defined(__linux__)
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ret = ioctl(fd, BLKGETSIZE64, &size);
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#elif defined(__APPLE__) && defined(__MACH__)
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ret = ioctl(fd, DKIOCGETBLOCKCOUNT, &size);
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#else
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close(fd);
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return 0;
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#endif
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if (ret) return 0;
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return size;
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}
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int is_block_device_fd(int fd __attribute__((unused))) {
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#ifdef _WIN32
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return 0;
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#else
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struct stat st;
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int ret = fstat(fd, &st);
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if (ret < 0) return 0;
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return S_ISBLK(st.st_mode);
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#endif
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}
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u64 get_file_size(int fd) {
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struct stat buf;
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int ret;
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u64 reserve_len = 0;
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s64 computed_size;
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ret = fstat(fd, &buf);
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if (ret) return 0;
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if (info.len < 0) reserve_len = -info.len;
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if (S_ISREG(buf.st_mode))
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computed_size = buf.st_size - reserve_len;
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else if (S_ISBLK(buf.st_mode))
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computed_size = get_block_device_size(fd) - reserve_len;
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else
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computed_size = 0;
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if (computed_size < 0) {
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warn("Computed filesystem size less than 0");
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computed_size = 0;
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}
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return computed_size;
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}
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static void read_block_group_descriptors(int fd) {
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size_t size = info.block_size * (size_t)aux_info.bg_desc_blocks;
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void* buf = malloc(size);
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ssize_t ret;
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if (!buf) critical_error("failed to alloc buffer");
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ret = read(fd, buf, size);
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if (ret < 0) {
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free(buf);
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critical_error_errno("failed to read block group descriptors");
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}
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if (ret != size) {
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free(buf);
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critical_error("failed to read all the block group descriptors");
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}
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const struct ext4_group_desc* gdp = (const struct ext4_group_desc*)buf;
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bool extended = (info.bg_desc_size >= EXT4_MIN_DESC_SIZE_64BIT);
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for (size_t i = 0; i < aux_info.groups; i++) {
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aux_info.bg_desc[i].bg_block_bitmap =
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(extended ? (u64)gdp->bg_block_bitmap_hi << 32 : 0) | gdp->bg_block_bitmap_lo;
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aux_info.bg_desc[i].bg_inode_bitmap =
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(extended ? (u64)gdp->bg_inode_bitmap_hi << 32 : 0) | gdp->bg_inode_bitmap_lo;
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aux_info.bg_desc[i].bg_inode_table =
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(extended ? (u64)gdp->bg_inode_table_hi << 32 : 0) | gdp->bg_inode_table_lo;
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aux_info.bg_desc[i].bg_free_blocks_count =
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(extended ? (u32)gdp->bg_free_blocks_count_hi << 16 : 0) |
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gdp->bg_free_blocks_count_lo;
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aux_info.bg_desc[i].bg_free_inodes_count =
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(extended ? (u32)gdp->bg_free_inodes_count_hi << 16 : 0) |
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gdp->bg_free_inodes_count_lo;
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aux_info.bg_desc[i].bg_used_dirs_count =
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(extended ? (u32)gdp->bg_used_dirs_count_hi << 16 : 0) | gdp->bg_used_dirs_count_lo;
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aux_info.bg_desc[i].bg_flags = gdp->bg_flags;
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gdp = (const struct ext4_group_desc*)((u8*)gdp + info.bg_desc_size);
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}
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free(buf);
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}
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int read_ext(int fd, int verbose) {
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off64_t ret;
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struct ext4_super_block sb;
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read_sb(fd, &sb);
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ext4_parse_sb_info(&sb);
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ret = lseek64(fd, info.len, SEEK_SET);
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if (ret < 0) critical_error_errno("failed to seek to end of input image");
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ret = lseek64(fd, info.block_size * (aux_info.first_data_block + 1), SEEK_SET);
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if (ret < 0) critical_error_errno("failed to seek to block group descriptors");
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read_block_group_descriptors(fd);
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if (verbose) {
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printf("Found filesystem with parameters:\n");
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printf(" Size: %" PRIu64 "\n", info.len);
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printf(" Block size: %d\n", info.block_size);
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printf(" Blocks per group: %d\n", info.blocks_per_group);
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printf(" Inodes per group: %d\n", info.inodes_per_group);
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printf(" Inode size: %d\n", info.inode_size);
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printf(" Label: %s\n", info.label);
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printf(" Blocks: %" PRIext4u64 "\n", aux_info.len_blocks);
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printf(" Block groups: %d\n", aux_info.groups);
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printf(" Reserved block group size: %d\n", info.bg_desc_reserve_blocks);
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printf(" Block group descriptor size: %d\n", info.bg_desc_size);
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printf(" Used %d/%d inodes and %d/%d blocks\n",
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aux_info.sb->s_inodes_count - aux_info.sb->s_free_inodes_count,
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aux_info.sb->s_inodes_count,
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aux_info.sb->s_blocks_count_lo - aux_info.sb->s_free_blocks_count_lo,
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aux_info.sb->s_blocks_count_lo);
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}
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return 0;
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}
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