mirror of https://github.com/ventoy/Ventoy
530 lines
15 KiB
C
530 lines
15 KiB
C
/*
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* Unsquash a squashfs filesystem. This is a highly compressed read only
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* filesystem.
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*
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* Copyright (c) 2009, 2010, 2013, 2019
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* Phillip Lougher <phillip@squashfs.org.uk>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2,
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* or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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* unsquash-2.c
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*/
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#include "unsquashfs.h"
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#include "squashfs_compat.h"
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static squashfs_fragment_entry_2 *fragment_table;
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static unsigned int *uid_table, *guid_table;
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static char *inode_table, *directory_table;
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static squashfs_operations ops;
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static void read_block_list(unsigned int *block_list, char *block_ptr, int blocks)
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{
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TRACE("read_block_list: blocks %d\n", blocks);
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if(swap) {
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SQUASHFS_SWAP_INTS_3(block_list, block_ptr, blocks);
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} else
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memcpy(block_list, block_ptr, blocks * sizeof(unsigned int));
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}
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static int read_fragment_table(long long *table_start)
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{
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/*
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* Note on overflow limits:
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* Size of SBlk.s.fragments is 2^32 (unsigned int)
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* Max size of bytes is 2^32*8 or 2^35
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* Max indexes is (2^32*8)/8K or 2^22
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* Max length is ((2^32*8)/8K)*4 or 2^24 or 16M
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*/
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int res, i;
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long long bytes = SQUASHFS_FRAGMENT_BYTES_2((long long) sBlk.s.fragments);
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int indexes = SQUASHFS_FRAGMENT_INDEXES_2((long long) sBlk.s.fragments);
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int length = SQUASHFS_FRAGMENT_INDEX_BYTES_2((long long) sBlk.s.fragments);
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unsigned int *fragment_table_index;
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/*
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* The size of the index table (length bytes) should match the
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* table start and end points
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*/
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if(length != (*table_start- sBlk.s.fragment_table_start)) {
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ERROR("read_ids: Bad inode count in super block\n");
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return FALSE;
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}
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TRACE("read_fragment_table: %d fragments, reading %d fragment indexes "
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"from 0x%llx\n", sBlk.s.fragments, indexes,
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sBlk.s.fragment_table_start);
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fragment_table_index = malloc(length);
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if(fragment_table_index == NULL)
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EXIT_UNSQUASH("read_fragment_table: failed to allocate "
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"fragment table index\n");
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fragment_table = malloc(bytes);
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if(fragment_table == NULL)
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EXIT_UNSQUASH("read_fragment_table: failed to allocate "
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"fragment table\n");
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if(swap) {
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unsigned int *sfragment_table_index = malloc(length);
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if(sfragment_table_index == NULL)
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EXIT_UNSQUASH("read_fragment_table: failed to allocate "
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"fragment table index\n");
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res = read_fs_bytes(fd, sBlk.s.fragment_table_start,
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length, sfragment_table_index);
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if(res == FALSE) {
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ERROR("read_fragment_table: failed to read fragment "
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"table index\n");
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free(sfragment_table_index);
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goto failed;
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}
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SQUASHFS_SWAP_FRAGMENT_INDEXES_2(fragment_table_index,
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sfragment_table_index, indexes);
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free(sfragment_table_index);
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} else {
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res = read_fs_bytes(fd, sBlk.s.fragment_table_start,
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length, fragment_table_index);
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if(res == FALSE) {
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ERROR("read_fragment_table: failed to read fragment "
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"table index\n");
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goto failed;
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}
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}
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for(i = 0; i < indexes; i++) {
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int expected = (i + 1) != indexes ? SQUASHFS_METADATA_SIZE :
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bytes & (SQUASHFS_METADATA_SIZE - 1);
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int length = read_block(fd, fragment_table_index[i], NULL,
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expected, ((char *) fragment_table) + ((long long) i *
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SQUASHFS_METADATA_SIZE));
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TRACE("Read fragment table block %d, from 0x%x, length %d\n", i,
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fragment_table_index[i], length);
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if(length == FALSE) {
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ERROR("read_fragment_table: failed to read fragment "
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"table block\n");
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goto failed;
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}
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}
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if(swap) {
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squashfs_fragment_entry_2 sfragment;
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for(i = 0; i < sBlk.s.fragments; i++) {
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SQUASHFS_SWAP_FRAGMENT_ENTRY_2((&sfragment),
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(&fragment_table[i]));
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memcpy((char *) &fragment_table[i], (char *) &sfragment,
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sizeof(squashfs_fragment_entry_2));
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}
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}
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*table_start = fragment_table_index[0];
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free(fragment_table_index);
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return TRUE;
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failed:
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free(fragment_table_index);
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return FALSE;
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}
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static void read_fragment(unsigned int fragment, long long *start_block, int *size)
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{
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TRACE("read_fragment: reading fragment %d\n", fragment);
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squashfs_fragment_entry_2 *fragment_entry = &fragment_table[fragment];
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*start_block = fragment_entry->start_block;
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*size = fragment_entry->size;
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}
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static struct inode *read_inode(unsigned int start_block, unsigned int offset)
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{
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static union squashfs_inode_header_2 header;
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long long start = sBlk.s.inode_table_start + start_block;
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int bytes = lookup_entry(inode_table_hash, start);
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char *block_ptr = inode_table + bytes + offset;
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static struct inode i;
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TRACE("read_inode: reading inode [%d:%d]\n", start_block, offset);
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if(bytes == -1)
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EXIT_UNSQUASH("read_inode: inode table block %lld not found\n",
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start);
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if(swap) {
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squashfs_base_inode_header_2 sinode;
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memcpy(&sinode, block_ptr, sizeof(header.base));
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SQUASHFS_SWAP_BASE_INODE_HEADER_2(&header.base, &sinode,
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sizeof(squashfs_base_inode_header_2));
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} else
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memcpy(&header.base, block_ptr, sizeof(header.base));
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i.xattr = SQUASHFS_INVALID_XATTR;
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i.uid = (uid_t) uid_table[header.base.uid];
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i.gid = header.base.guid == SQUASHFS_GUIDS ? i.uid :
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(uid_t) guid_table[header.base.guid];
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i.mode = lookup_type[header.base.inode_type] | header.base.mode;
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i.type = header.base.inode_type;
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i.time = sBlk.s.mkfs_time;
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i.inode_number = inode_number++;
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switch(header.base.inode_type) {
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case SQUASHFS_DIR_TYPE: {
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squashfs_dir_inode_header_2 *inode = &header.dir;
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if(swap) {
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squashfs_dir_inode_header_2 sinode;
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memcpy(&sinode, block_ptr, sizeof(header.dir));
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SQUASHFS_SWAP_DIR_INODE_HEADER_2(&header.dir,
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&sinode);
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} else
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memcpy(&header.dir, block_ptr,
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sizeof(header.dir));
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i.data = inode->file_size;
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i.offset = inode->offset;
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i.start = inode->start_block;
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i.time = inode->mtime;
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break;
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}
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case SQUASHFS_LDIR_TYPE: {
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squashfs_ldir_inode_header_2 *inode = &header.ldir;
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if(swap) {
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squashfs_ldir_inode_header_2 sinode;
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memcpy(&sinode, block_ptr, sizeof(header.ldir));
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SQUASHFS_SWAP_LDIR_INODE_HEADER_2(&header.ldir,
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&sinode);
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} else
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memcpy(&header.ldir, block_ptr,
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sizeof(header.ldir));
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i.data = inode->file_size;
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i.offset = inode->offset;
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i.start = inode->start_block;
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i.time = inode->mtime;
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break;
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}
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case SQUASHFS_FILE_TYPE: {
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squashfs_reg_inode_header_2 *inode = &header.reg;
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if(swap) {
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squashfs_reg_inode_header_2 sinode;
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memcpy(&sinode, block_ptr, sizeof(sinode));
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SQUASHFS_SWAP_REG_INODE_HEADER_2(inode,
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&sinode);
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} else
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memcpy(inode, block_ptr, sizeof(*inode));
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i.data = inode->file_size;
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i.time = inode->mtime;
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i.frag_bytes = inode->fragment == SQUASHFS_INVALID_FRAG
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? 0 : inode->file_size % sBlk.s.block_size;
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i.fragment = inode->fragment;
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i.offset = inode->offset;
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i.blocks = inode->fragment == SQUASHFS_INVALID_FRAG ?
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(i.data + sBlk.s.block_size - 1) >>
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sBlk.s.block_log : i.data >>
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sBlk.s.block_log;
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i.start = inode->start_block;
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i.sparse = 0;
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i.block_ptr = block_ptr + sizeof(*inode);
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break;
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}
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case SQUASHFS_SYMLINK_TYPE: {
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squashfs_symlink_inode_header_2 *inodep =
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&header.symlink;
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if(swap) {
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squashfs_symlink_inode_header_2 sinodep;
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memcpy(&sinodep, block_ptr, sizeof(sinodep));
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SQUASHFS_SWAP_SYMLINK_INODE_HEADER_2(inodep,
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&sinodep);
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} else
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memcpy(inodep, block_ptr, sizeof(*inodep));
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i.symlink = malloc(inodep->symlink_size + 1);
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if(i.symlink == NULL)
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EXIT_UNSQUASH("read_inode: failed to malloc "
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"symlink data\n");
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strncpy(i.symlink, block_ptr +
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sizeof(squashfs_symlink_inode_header_2),
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inodep->symlink_size);
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i.symlink[inodep->symlink_size] = '\0';
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i.data = inodep->symlink_size;
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break;
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}
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case SQUASHFS_BLKDEV_TYPE:
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case SQUASHFS_CHRDEV_TYPE: {
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squashfs_dev_inode_header_2 *inodep = &header.dev;
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if(swap) {
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squashfs_dev_inode_header_2 sinodep;
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memcpy(&sinodep, block_ptr, sizeof(sinodep));
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SQUASHFS_SWAP_DEV_INODE_HEADER_2(inodep,
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&sinodep);
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} else
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memcpy(inodep, block_ptr, sizeof(*inodep));
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i.data = inodep->rdev;
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break;
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}
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case SQUASHFS_FIFO_TYPE:
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case SQUASHFS_SOCKET_TYPE:
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i.data = 0;
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break;
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default:
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EXIT_UNSQUASH("Unknown inode type %d in "
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"read_inode_header_2!\n",
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header.base.inode_type);
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}
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return &i;
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}
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static struct dir *squashfs_opendir(unsigned int block_start, unsigned int offset,
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struct inode **i)
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{
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squashfs_dir_header_2 dirh;
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char buffer[sizeof(squashfs_dir_entry_2) + SQUASHFS_NAME_LEN + 1]
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__attribute__((aligned));
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squashfs_dir_entry_2 *dire = (squashfs_dir_entry_2 *) buffer;
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long long start;
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int bytes;
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int dir_count, size;
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struct dir_ent *new_dir;
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struct dir *dir;
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TRACE("squashfs_opendir: inode start block %d, offset %d\n",
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block_start, offset);
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*i = read_inode(block_start, offset);
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dir = malloc(sizeof(struct dir));
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if(dir == NULL)
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EXIT_UNSQUASH("squashfs_opendir: malloc failed!\n");
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dir->dir_count = 0;
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dir->cur_entry = 0;
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dir->mode = (*i)->mode;
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dir->uid = (*i)->uid;
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dir->guid = (*i)->gid;
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dir->mtime = (*i)->time;
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dir->xattr = (*i)->xattr;
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dir->dirs = NULL;
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if ((*i)->data == 0)
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/*
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* if the directory is empty, skip the unnecessary
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* lookup_entry, this fixes the corner case with
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* completely empty filesystems where lookup_entry correctly
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* returning -1 is incorrectly treated as an error
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*/
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return dir;
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start = sBlk.s.directory_table_start + (*i)->start;
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bytes = lookup_entry(directory_table_hash, start);
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if(bytes == -1)
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EXIT_UNSQUASH("squashfs_opendir: directory block %d not "
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"found!\n", block_start);
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bytes += (*i)->offset;
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size = (*i)->data + bytes;
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while(bytes < size) {
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if(swap) {
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squashfs_dir_header_2 sdirh;
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memcpy(&sdirh, directory_table + bytes, sizeof(sdirh));
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SQUASHFS_SWAP_DIR_HEADER_2(&dirh, &sdirh);
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} else
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memcpy(&dirh, directory_table + bytes, sizeof(dirh));
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dir_count = dirh.count + 1;
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TRACE("squashfs_opendir: Read directory header @ byte position "
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"%d, %d directory entries\n", bytes, dir_count);
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bytes += sizeof(dirh);
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/* dir_count should never be larger than SQUASHFS_DIR_COUNT */
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if(dir_count > SQUASHFS_DIR_COUNT) {
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ERROR("File system corrupted: too many entries in directory\n");
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goto corrupted;
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}
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while(dir_count--) {
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if(swap) {
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squashfs_dir_entry_2 sdire;
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memcpy(&sdire, directory_table + bytes,
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sizeof(sdire));
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SQUASHFS_SWAP_DIR_ENTRY_2(dire, &sdire);
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} else
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memcpy(dire, directory_table + bytes,
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sizeof(*dire));
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bytes += sizeof(*dire);
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/* size should never be SQUASHFS_NAME_LEN or larger */
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if(dire->size >= SQUASHFS_NAME_LEN) {
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ERROR("File system corrupted: filename too long\n");
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goto corrupted;
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}
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memcpy(dire->name, directory_table + bytes,
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dire->size + 1);
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dire->name[dire->size + 1] = '\0';
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TRACE("squashfs_opendir: directory entry %s, inode "
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"%d:%d, type %d\n", dire->name,
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dirh.start_block, dire->offset, dire->type);
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if((dir->dir_count % DIR_ENT_SIZE) == 0) {
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new_dir = realloc(dir->dirs, (dir->dir_count +
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DIR_ENT_SIZE) * sizeof(struct dir_ent));
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if(new_dir == NULL)
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EXIT_UNSQUASH("squashfs_opendir: "
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"realloc failed!\n");
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dir->dirs = new_dir;
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}
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strcpy(dir->dirs[dir->dir_count].name, dire->name);
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dir->dirs[dir->dir_count].start_block =
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dirh.start_block;
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dir->dirs[dir->dir_count].offset = dire->offset;
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dir->dirs[dir->dir_count].type = dire->type;
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dir->dir_count ++;
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bytes += dire->size + 1;
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}
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}
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return dir;
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corrupted:
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free(dir->dirs);
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free(dir);
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return NULL;
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}
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squashfs_operations *read_filesystem_tables_2()
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{
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long long table_start;
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/* Read uid and gid lookup tables */
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/* Sanity check super block contents */
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if(sBlk.no_guids) {
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if(sBlk.guid_start >= sBlk.s.bytes_used) {
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ERROR("read_filesystem_tables: gid start too large in super block\n");
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goto corrupted;
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}
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if(read_ids(sBlk.no_guids, sBlk.guid_start, sBlk.s.bytes_used, &guid_table) == FALSE)
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goto corrupted;
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table_start = sBlk.guid_start;
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} else {
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/* no guids, guid_start should be 0 */
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if(sBlk.guid_start != 0) {
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ERROR("read_filesystem_tables: gid start too large in super block\n");
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goto corrupted;
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}
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table_start = sBlk.s.bytes_used;
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}
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if(sBlk.uid_start >= table_start) {
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ERROR("read_filesystem_tables: uid start too large in super block\n");
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goto corrupted;
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}
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/* There should be at least one uid */
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if(sBlk.no_uids == 0) {
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ERROR("read_filesystem_tables: uid count bad in super block\n");
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goto corrupted;
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}
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if(read_ids(sBlk.no_uids, sBlk.uid_start, table_start, &uid_table) == FALSE)
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goto corrupted;
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table_start = sBlk.uid_start;
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/* Read fragment table */
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if(sBlk.s.fragments != 0) {
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/* Sanity check super block contents */
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if(sBlk.s.fragment_table_start >= table_start) {
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ERROR("read_filesystem_tables: fragment table start too large in super block\n");
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goto corrupted;
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}
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/* The number of fragments should not exceed the number of inodes */
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if(sBlk.s.fragments > sBlk.s.inodes) {
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ERROR("read_filesystem_tables: Bad fragment count in super block\n");
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goto corrupted;
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}
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if(read_fragment_table(&table_start) == FALSE)
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goto corrupted;
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} else {
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/*
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* Sanity check super block contents - with 0 fragments,
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* the fragment table should be empty
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*/
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if(sBlk.s.fragment_table_start != table_start) {
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ERROR("read_filesystem_tables: fragment table start invalid in super block\n");
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goto corrupted;
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}
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}
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/* Read directory table */
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|
|
|
/* Sanity check super block contents */
|
|
if(sBlk.s.directory_table_start > table_start) {
|
|
ERROR("read_filesystem_tables: directory table start too large in super block\n");
|
|
goto corrupted;
|
|
}
|
|
|
|
directory_table = read_directory_table(sBlk.s.directory_table_start,
|
|
table_start);
|
|
if(directory_table == NULL)
|
|
goto corrupted;
|
|
|
|
/* Read inode table */
|
|
|
|
/* Sanity check super block contents */
|
|
if(sBlk.s.inode_table_start >= sBlk.s.directory_table_start) {
|
|
ERROR("read_filesystem_tables: inode table start too large in super block\n");
|
|
goto corrupted;
|
|
}
|
|
|
|
inode_table = read_inode_table(sBlk.s.inode_table_start,
|
|
sBlk.s.directory_table_start);
|
|
if(inode_table == NULL)
|
|
goto corrupted;
|
|
|
|
return &ops;
|
|
|
|
corrupted:
|
|
ERROR("File system corruption detected\n");
|
|
return NULL;
|
|
}
|
|
|
|
|
|
static squashfs_operations ops = {
|
|
.opendir = squashfs_opendir,
|
|
.read_fragment = read_fragment,
|
|
.read_block_list = read_block_list,
|
|
.read_inode = read_inode
|
|
};
|