lib/ext2fs/csum.c - platform/external/e2fsprogs - Git at Google

 /*
  * csum.c --- checksumming of ext3 structures
  *
  * Copyright (C) 2006 Cluster File Systems, Inc.
  * Copyright (C) 2006, 2007 by Andreas Dilger <adilger@clusterfs.com>
  *
  * %Begin-Header%
  * This file may be redistributed under the terms of the GNU Library
  * General Public License, version 2.
  * %End-Header%
  */

 #if HAVE_SYS_TYPES_H
 #include <sys/types.h>
 #endif

 #include "ext2_fs.h"
 #include "ext2fs.h"
 #include "crc16.h"
 #include <assert.h>

 #ifndef offsetof
 #define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
 #endif

 #ifdef DEBUG
 #define STATIC
 #else
 #define STATIC static
 #endif

 STATIC __u16 ext2fs_group_desc_csum(ext2_filsys fs, dgrp_t group)
 {
 	__u16 crc = 0;
 	struct ext2_group_desc *desc;

 	desc = &fs->group_desc[group];

 	if (fs->super->s_feature_ro_compat & EXT4_FEATURE_RO_COMPAT_GDT_CSUM) {
 		int offset = offsetof(struct ext2_group_desc, bg_checksum);

 #ifdef WORDS_BIGENDIAN
 		struct ext2_group_desc swabdesc = *desc;

 		/* Have to swab back to little-endian to do the checksum */
 		ext2fs_swap_group_desc(&swabdesc);
 		desc = &swabdesc;

 		group = ext2fs_swab32(group);
 #endif
 		crc = ext2fs_crc16(~0, fs->super->s_uuid,
 				   sizeof(fs->super->s_uuid));
 		crc = ext2fs_crc16(crc, &group, sizeof(group));
 		crc = ext2fs_crc16(crc, desc, offset);
 		offset += sizeof(desc->bg_checksum); /* skip checksum */
 		assert(offset == sizeof(*desc));
 		/* for checksum of struct ext4_group_desc do the rest...*/
 		if (offset < fs->super->s_desc_size) {
 			crc = ext2fs_crc16(crc, (char *)desc + offset,
 				    fs->super->s_desc_size - offset);
 		}
 	}

 	return crc;
 }

 int ext2fs_group_desc_csum_verify(ext2_filsys fs, dgrp_t group)
 {
 	if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 				       EXT4_FEATURE_RO_COMPAT_GDT_CSUM) &&
 	    (fs->group_desc[group].bg_checksum !=
 	     ext2fs_group_desc_csum(fs, group)))
 		return 0;

 	return 1;
 }

 void ext2fs_group_desc_csum_set(ext2_filsys fs, dgrp_t group)
 {
 	if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 				       EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
 		fs->group_desc[group].bg_checksum =
 			ext2fs_group_desc_csum(fs, group);
 }

 static __u32 find_last_inode_ingrp(ext2fs_inode_bitmap bitmap,
 				   __u32 inodes_per_grp, dgrp_t grp_no)
 {
 	ext2_ino_t i, start_ino, end_ino;

 	start_ino = grp_no * inodes_per_grp + 1;
 	end_ino = start_ino + inodes_per_grp - 1;

 	for (i = end_ino; i >= start_ino; i--) {
 		if (ext2fs_fast_test_inode_bitmap(bitmap, i))
 			return i - start_ino + 1;
 	}
 	return inodes_per_grp;
 }

 /* update the bitmap flags, set the itable high watermark, and calculate
  * checksums for the group descriptors */
 errcode_t ext2fs_set_gdt_csum(ext2_filsys fs)
 {
 	struct ext2_super_block *sb = fs->super;
 	struct ext2_group_desc *bg = fs->group_desc;
 	int dirty = 0;
 	dgrp_t i;

 	if (!fs->inode_map)
 		return EXT2_ET_NO_INODE_BITMAP;

 	if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
 					EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
 		return 0;

 	for (i = 0; i < fs->group_desc_count; i++, bg++) {
 		int old_csum = bg->bg_checksum;
 		int old_unused = bg->bg_itable_unused;
 		int old_flags = bg->bg_flags;

 		if (bg->bg_free_inodes_count == sb->s_inodes_per_group) {
 			bg->bg_flags |= EXT2_BG_INODE_UNINIT;
 			bg->bg_itable_unused = sb->s_inodes_per_group;
 		} else {
 			bg->bg_flags &= ~EXT2_BG_INODE_UNINIT;
 			bg->bg_itable_unused = sb->s_inodes_per_group -
 				find_last_inode_ingrp(fs->inode_map,
 						      sb->s_inodes_per_group,i);
 		}

 		ext2fs_group_desc_csum_set(fs, i);
 		if (old_flags != bg->bg_flags)
 			dirty = 1;
 		if (old_unused != bg->bg_itable_unused)
 			dirty = 1;
 		if (old_csum != bg->bg_checksum)
 			dirty = 1;
 	}
 	if (dirty)
 		ext2fs_mark_super_dirty(fs);
 	return 0;
 }

 #ifdef DEBUG
 #include "e2p/e2p.h"

 void print_csum(const char *msg, ext2_filsys fs, dgrp_t group)
 {
 	__u16 crc1, crc2, crc3;
 	dgrp_t swabgroup;
 	struct ext2_group_desc *desc = &fs->group_desc[group];
 	struct ext2_super_block *sb = fs->super;

 #ifdef WORDS_BIGENDIAN
 	struct ext2_group_desc swabdesc = fs->group_desc[group];

 	/* Have to swab back to little-endian to do the checksum */
 	ext2fs_swap_group_desc(&swabdesc);
 	desc = &swabdesc;

 	swabgroup = ext2fs_swab32(group);
 #else
 	swabgroup = group;
 #endif

 	crc1 = ext2fs_crc16(~0, sb->s_uuid, sizeof(fs->super->s_uuid));
 	crc2 = ext2fs_crc16(crc1, &swabgroup, sizeof(swabgroup));
 	crc3 = ext2fs_crc16(crc2, desc,
 			    offsetof(struct ext2_group_desc, bg_checksum));
 	printf("%s: UUID %s(%04x), grp %u(%04x): %04x=%04x\n",
 	       msg, e2p_uuid2str(sb->s_uuid), crc1, group, crc2,crc3,
 	       ext2fs_group_desc_csum(fs, group));
 }

 unsigned char sb_uuid[16] = { 0x4f, 0x25, 0xe8, 0xcf, 0xe7, 0x97, 0x48, 0x23,
 			      0xbe, 0xfa, 0xa7, 0x88, 0x4b, 0xae, 0xec, 0xdb };

 int main(int argc, char **argv)
 {
 	struct ext2_super_block param;
 	errcode_t		retval;
 	ext2_filsys		fs;
 	int			i;
 	__u16 csum1, csum2, csum_known = 0xd3a4;

 	memset(&param, 0, sizeof(param));
 	param.s_blocks_count = 32768;

 	retval = ext2fs_initialize("test fs", 0, &param,
 				   test_io_manager, &fs);
 	if (retval) {
 		com_err("setup", retval,
 			"While initializing filesystem");
 		exit(1);
 	}
 	memcpy(fs->super->s_uuid, sb_uuid, 16);
 	fs->super->s_feature_ro_compat = EXT4_FEATURE_RO_COMPAT_GDT_CSUM;

 	for (i=0; i < fs->group_desc_count; i++) {
 		fs->group_desc[i].bg_block_bitmap = 124;
 		fs->group_desc[i].bg_inode_bitmap = 125;
 		fs->group_desc[i].bg_inode_table = 126;
 		fs->group_desc[i].bg_free_blocks_count = 31119;
 		fs->group_desc[i].bg_free_inodes_count = 15701;
 		fs->group_desc[i].bg_used_dirs_count = 2;
 		fs->group_desc[i].bg_flags = 0;
 	};

 	csum1 = ext2fs_group_desc_csum(fs, 0);
 	print_csum("csum0000", fs, 0);

 	if (csum1 != csum_known) {
 		printf("checksum for group 0 should be %04x\n", csum_known);
 		exit(1);
 	}
 	csum2 = ext2fs_group_desc_csum(fs, 1);
 	print_csum("csum0001", fs, 1);
 	if (csum1 == csum2) {
 		printf("checksums for different groups shouldn't match\n");
 		exit(1);
 	}
 	csum2 = ext2fs_group_desc_csum(fs, 2);
 	print_csum("csumffff", fs, 2);
 	if (csum1 == csum2) {
 		printf("checksums for different groups shouldn't match\n");
 		exit(1);
 	}
 	fs->group_desc[0].bg_checksum = csum1;
 	csum2 = ext2fs_group_desc_csum(fs, 0);
 	print_csum("csum_set", fs, 0);
 	if (csum1 != csum2) {
 		printf("checksums should not depend on checksum field\n");
 		exit(1);
 	}
 	if (!ext2fs_group_desc_csum_verify(fs, 0)) {
 		printf("checksums should verify against gd_checksum\n");
 		exit(1);
 	}
 	memset(fs->super->s_uuid, 0x30, sizeof(fs->super->s_uuid));
 	print_csum("new_uuid", fs, 0);
 	if (ext2fs_group_desc_csum_verify(fs, 0) != 0) {
 		printf("checksums for different filesystems shouldn't match\n");
 		exit(1);
 	}
 	csum1 = fs->group_desc[0].bg_checksum = ext2fs_group_desc_csum(fs, 0);
 	print_csum("csum_new", fs, 0);
 	fs->group_desc[0].bg_free_blocks_count = 1;
 	csum2 = ext2fs_group_desc_csum(fs, 0);
 	print_csum("csum_blk", fs, 0);
 	if (csum1 == csum2) {
 		printf("checksums for different data shouldn't match\n");
 		exit(1);
 	}

 	return 0;
 }
 #endif
	/*
	* csum.c --- checksumming of ext3 structures
	*
	* Copyright (C) 2006 Cluster File Systems, Inc.
	* Copyright (C) 2006, 2007 by Andreas Dilger <adilger@clusterfs.com>
	*
	* %Begin-Header%
	* This file may be redistributed under the terms of the GNU Library
	* General Public License, version 2.
	* %End-Header%
	*/

	#if HAVE_SYS_TYPES_H
	#include <sys/types.h>
	#endif

	#include "ext2_fs.h"
	#include "ext2fs.h"
	#include "crc16.h"
	#include <assert.h>

	#ifndef offsetof
	#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
	#endif

	#ifdef DEBUG
	#define STATIC
	#else
	#define STATIC static
	#endif

	STATIC __u16 ext2fs_group_desc_csum(ext2_filsys fs, dgrp_t group)
	{
	__u16 crc = 0;
	struct ext2_group_desc *desc;

	desc = &fs->group_desc[group];

	if (fs->super->s_feature_ro_compat & EXT4_FEATURE_RO_COMPAT_GDT_CSUM) {
	int offset = offsetof(struct ext2_group_desc, bg_checksum);

	#ifdef WORDS_BIGENDIAN
	struct ext2_group_desc swabdesc = *desc;

	/* Have to swab back to little-endian to do the checksum */
	ext2fs_swap_group_desc(&swabdesc);
	desc = &swabdesc;

	group = ext2fs_swab32(group);
	#endif
	crc = ext2fs_crc16(~0, fs->super->s_uuid,
	sizeof(fs->super->s_uuid));
	crc = ext2fs_crc16(crc, &group, sizeof(group));
	crc = ext2fs_crc16(crc, desc, offset);
	offset += sizeof(desc->bg_checksum); /* skip checksum */
	assert(offset == sizeof(*desc));
	/* for checksum of struct ext4_group_desc do the rest...*/
	if (offset < fs->super->s_desc_size) {
	crc = ext2fs_crc16(crc, (char *)desc + offset,
	fs->super->s_desc_size - offset);
	}
	}

	return crc;
	}

	int ext2fs_group_desc_csum_verify(ext2_filsys fs, dgrp_t group)
	{
	if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
	EXT4_FEATURE_RO_COMPAT_GDT_CSUM) &&
	(fs->group_desc[group].bg_checksum !=
	ext2fs_group_desc_csum(fs, group)))
	return 0;

	return 1;
	}

	void ext2fs_group_desc_csum_set(ext2_filsys fs, dgrp_t group)
	{
	if (EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
	EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
	fs->group_desc[group].bg_checksum =
	ext2fs_group_desc_csum(fs, group);
	}

	static __u32 find_last_inode_ingrp(ext2fs_inode_bitmap bitmap,
	__u32 inodes_per_grp, dgrp_t grp_no)
	{
	ext2_ino_t i, start_ino, end_ino;

	start_ino = grp_no * inodes_per_grp + 1;
	end_ino = start_ino + inodes_per_grp - 1;

	for (i = end_ino; i >= start_ino; i--) {
	if (ext2fs_fast_test_inode_bitmap(bitmap, i))
	return i - start_ino + 1;
	}
	return inodes_per_grp;
	}

	/* update the bitmap flags, set the itable high watermark, and calculate
	* checksums for the group descriptors */
	errcode_t ext2fs_set_gdt_csum(ext2_filsys fs)
	{
	struct ext2_super_block *sb = fs->super;
	struct ext2_group_desc *bg = fs->group_desc;
	int dirty = 0;
	dgrp_t i;

	if (!fs->inode_map)
	return EXT2_ET_NO_INODE_BITMAP;

	if (!EXT2_HAS_RO_COMPAT_FEATURE(fs->super,
	EXT4_FEATURE_RO_COMPAT_GDT_CSUM))
	return 0;

	for (i = 0; i < fs->group_desc_count; i++, bg++) {
	int old_csum = bg->bg_checksum;
	int old_unused = bg->bg_itable_unused;
	int old_flags = bg->bg_flags;

	if (bg->bg_free_inodes_count == sb->s_inodes_per_group) {
	bg->bg_flags \|= EXT2_BG_INODE_UNINIT;
	bg->bg_itable_unused = sb->s_inodes_per_group;
	} else {
	bg->bg_flags &= ~EXT2_BG_INODE_UNINIT;
	bg->bg_itable_unused = sb->s_inodes_per_group -
	find_last_inode_ingrp(fs->inode_map,
	sb->s_inodes_per_group,i);
	}

	ext2fs_group_desc_csum_set(fs, i);
	if (old_flags != bg->bg_flags)
	dirty = 1;
	if (old_unused != bg->bg_itable_unused)
	dirty = 1;
	if (old_csum != bg->bg_checksum)
	dirty = 1;
	}
	if (dirty)
	ext2fs_mark_super_dirty(fs);
	return 0;
	}

	#ifdef DEBUG
	#include "e2p/e2p.h"

	void print_csum(const char *msg, ext2_filsys fs, dgrp_t group)
	{
	__u16 crc1, crc2, crc3;
	dgrp_t swabgroup;
	struct ext2_group_desc *desc = &fs->group_desc[group];
	struct ext2_super_block *sb = fs->super;

	#ifdef WORDS_BIGENDIAN
	struct ext2_group_desc swabdesc = fs->group_desc[group];

	/* Have to swab back to little-endian to do the checksum */
	ext2fs_swap_group_desc(&swabdesc);
	desc = &swabdesc;

	swabgroup = ext2fs_swab32(group);
	#else
	swabgroup = group;
	#endif

	crc1 = ext2fs_crc16(~0, sb->s_uuid, sizeof(fs->super->s_uuid));
	crc2 = ext2fs_crc16(crc1, &swabgroup, sizeof(swabgroup));
	crc3 = ext2fs_crc16(crc2, desc,
	offsetof(struct ext2_group_desc, bg_checksum));
	printf("%s: UUID %s(%04x), grp %u(%04x): %04x=%04x\n",
	msg, e2p_uuid2str(sb->s_uuid), crc1, group, crc2,crc3,
	ext2fs_group_desc_csum(fs, group));
	}

	unsigned char sb_uuid[16] = { 0x4f, 0x25, 0xe8, 0xcf, 0xe7, 0x97, 0x48, 0x23,
	0xbe, 0xfa, 0xa7, 0x88, 0x4b, 0xae, 0xec, 0xdb };

	int main(int argc, char **argv)
	{
	struct ext2_super_block param;
	errcode_t retval;
	ext2_filsys fs;
	int i;
	__u16 csum1, csum2, csum_known = 0xd3a4;

	memset(&param, 0, sizeof(param));
	param.s_blocks_count = 32768;

	retval = ext2fs_initialize("test fs", 0, &param,
	test_io_manager, &fs);
	if (retval) {
	com_err("setup", retval,
	"While initializing filesystem");
	exit(1);
	}
	memcpy(fs->super->s_uuid, sb_uuid, 16);
	fs->super->s_feature_ro_compat = EXT4_FEATURE_RO_COMPAT_GDT_CSUM;

	for (i=0; i < fs->group_desc_count; i++) {
	fs->group_desc[i].bg_block_bitmap = 124;
	fs->group_desc[i].bg_inode_bitmap = 125;
	fs->group_desc[i].bg_inode_table = 126;
	fs->group_desc[i].bg_free_blocks_count = 31119;
	fs->group_desc[i].bg_free_inodes_count = 15701;
	fs->group_desc[i].bg_used_dirs_count = 2;
	fs->group_desc[i].bg_flags = 0;
	};

	csum1 = ext2fs_group_desc_csum(fs, 0);
	print_csum("csum0000", fs, 0);

	if (csum1 != csum_known) {
	printf("checksum for group 0 should be %04x\n", csum_known);
	exit(1);
	}
	csum2 = ext2fs_group_desc_csum(fs, 1);
	print_csum("csum0001", fs, 1);
	if (csum1 == csum2) {
	printf("checksums for different groups shouldn't match\n");
	exit(1);
	}
	csum2 = ext2fs_group_desc_csum(fs, 2);
	print_csum("csumffff", fs, 2);
	if (csum1 == csum2) {
	printf("checksums for different groups shouldn't match\n");
	exit(1);
	}
	fs->group_desc[0].bg_checksum = csum1;
	csum2 = ext2fs_group_desc_csum(fs, 0);
	print_csum("csum_set", fs, 0);
	if (csum1 != csum2) {
	printf("checksums should not depend on checksum field\n");
	exit(1);
	}
	if (!ext2fs_group_desc_csum_verify(fs, 0)) {
	printf("checksums should verify against gd_checksum\n");
	exit(1);
	}
	memset(fs->super->s_uuid, 0x30, sizeof(fs->super->s_uuid));
	print_csum("new_uuid", fs, 0);
	if (ext2fs_group_desc_csum_verify(fs, 0) != 0) {
	printf("checksums for different filesystems shouldn't match\n");
	exit(1);
	}
	csum1 = fs->group_desc[0].bg_checksum = ext2fs_group_desc_csum(fs, 0);
	print_csum("csum_new", fs, 0);
	fs->group_desc[0].bg_free_blocks_count = 1;
	csum2 = ext2fs_group_desc_csum(fs, 0);
	print_csum("csum_blk", fs, 0);
	if (csum1 == csum2) {
	printf("checksums for different data shouldn't match\n");
	exit(1);
	}

	return 0;
	}
	#endif