super.c

Linux内核源代码 为压缩文件 是<<Linux内核>>一书中的源代码

/*
 *  super.c
 *
 *  Copyright (C) 1995-1997, 1999 Martin von L鰓is
 *  Copyright (C) 1996-1997 R間is Duchesne
 *  Copyright (C) 1999 Steve Dodd
 *  Copyright (C) 2000 Anton Altparmakov
 */

#include "ntfstypes.h"
#include "struct.h"
#include "super.h"

#include <linux/errno.h>
#include "macros.h"
#include "inode.h"
#include "support.h"
#include "util.h"

/*
 * All important structures in NTFS use 2 consistency checks :
 * . a magic structure identifier (FILE, INDX, RSTR, RCRD...)
 * . a fixup technique : the last word of each sector (called a fixup) of a
 *   structure's record should end with the word at offset <n> of the first
 *   sector, and if it is the case, must be replaced with the words following
 *   <n>. The value of <n> and the number of fixups is taken from the fields
 *   at the offsets 4 and 6.
 *
 * This function perform these 2 checks, and _fails_ if :
 * . the magic identifier is wrong
 * . the size is given and does not match the number of sectors
 * . a fixup is invalid
 */
int ntfs_fixup_record(ntfs_volume *vol, char *record, char *magic, int size)
{
	int start, count, offset;
	ntfs_u16 fixup;

	if(!IS_MAGIC(record,magic))
		return 0;
	start=NTFS_GETU16(record+4);
	count=NTFS_GETU16(record+6);
	count--;
	if(size && vol->blocksize*count != size)
		return 0;
	fixup = NTFS_GETU16(record+start);
	start+=2;
	offset=vol->blocksize-2;
	while(count--){
		if(NTFS_GETU16(record+offset)!=fixup)
			return 0;
		NTFS_PUTU16(record+offset, NTFS_GETU16(record+start));
		start+=2;
		offset+=vol->blocksize;
	}
	return 1;
}

/* Get vital informations about the ntfs partition from the boot sector */
int ntfs_init_volume(ntfs_volume *vol,char *boot)
{
	/* Historical default values, in case we don't load $AttrDef */
	vol->at_standard_information=0x10;
	vol->at_attribute_list=0x20;
	vol->at_file_name=0x30;
	vol->at_volume_version=0x40;
	vol->at_security_descriptor=0x50;
	vol->at_volume_name=0x60;
	vol->at_volume_information=0x70;
	vol->at_data=0x80;
	vol->at_index_root=0x90;
	vol->at_index_allocation=0xA0;
	vol->at_bitmap=0xB0;
	vol->at_symlink=0xC0;

	/* Sector size */
	vol->blocksize=NTFS_GETU16(boot+0xB);
	vol->clusterfactor=NTFS_GETU8(boot+0xD);
	vol->mft_clusters_per_record=NTFS_GETS8(boot+0x40);
	vol->index_clusters_per_record=NTFS_GETS8(boot+0x44);
	
	/* Just some consistency checks */
	if(NTFS_GETU32(boot+0x40)>256)
		ntfs_error("Unexpected data #1 in boot block\n");
	if(NTFS_GETU32(boot+0x44)>256)
		ntfs_error("Unexpected data #2 in boot block\n");
	if(vol->index_clusters_per_record<0){
		ntfs_error("Unexpected data #3 in boot block\n");
		/* If this really means a fraction, setting it to 1
		   should be safe. */
		vol->index_clusters_per_record=1;
	}
	/* in some cases, 0xF6 meant 1024 bytes. Other strange values have not
	   been observed */
	if(vol->mft_clusters_per_record<0 && vol->mft_clusters_per_record!=-10)
		ntfs_error("Unexpected data #4 in boot block\n");

	vol->clustersize=vol->blocksize*vol->clusterfactor;
	if(vol->mft_clusters_per_record>0)
		vol->mft_recordsize=
			vol->clustersize*vol->mft_clusters_per_record;
	else
		vol->mft_recordsize=1<<(-vol->mft_clusters_per_record);
	vol->index_recordsize=vol->clustersize*vol->index_clusters_per_record;
	/* FIXME: long long value */
	vol->mft_cluster=NTFS_GETU64(boot+0x30);

	/* This will be initialized later */
	vol->upcase=0;
	vol->upcase_length=0;
	vol->mft_ino=0;
	return 0;
}

static void 
ntfs_init_upcase(ntfs_inode *upcase)
{
	ntfs_io io;
#define UPCASE_LENGTH  256
	upcase->vol->upcase = ntfs_malloc(2*UPCASE_LENGTH);
	if( !upcase->vol->upcase )
		return;
	io.fn_put=ntfs_put;
	io.fn_get=0;
	io.param=(char*)upcase->vol->upcase;
	io.size=2*UPCASE_LENGTH;
	ntfs_read_attr(upcase,upcase->vol->at_data,0,0,&io);
	upcase->vol->upcase_length = io.size / 2;
}

static int
process_attrdef(ntfs_inode* attrdef,ntfs_u8* def)
{
	int type = NTFS_GETU32(def+0x80);
	int check_type = 0;
	ntfs_volume *vol=attrdef->vol;
	ntfs_u16* name = (ntfs_u16*)def;

	if(ntfs_ua_strncmp(name,"$STANDARD_INFORMATION",64)==0){
		vol->at_standard_information=type;
		check_type=0x10;
	}else if(ntfs_ua_strncmp(name,"$ATTRIBUTE_LIST",64)==0){
		vol->at_attribute_list=type;
		check_type=0x20;
	}else if(ntfs_ua_strncmp(name,"$FILE_NAME",64)==0){
		vol->at_file_name=type;
		check_type=0x30;
	}else if(ntfs_ua_strncmp(name,"$VOLUME_VERSION",64)==0){
		vol->at_volume_version=type;
		check_type=0x40;
	}else if(ntfs_ua_strncmp(name,"$SECURITY_DESCRIPTOR",64)==0){
		vol->at_security_descriptor=type;
		check_type=0x50;
	}else if(ntfs_ua_strncmp(name,"$VOLUME_NAME",64)==0){
		vol->at_volume_name=type;
		check_type=0x60;
	}else if(ntfs_ua_strncmp(name,"$VOLUME_INFORMATION",64)==0){
		vol->at_volume_information=type;
		check_type=0x70;
	}else if(ntfs_ua_strncmp(name,"$DATA",64)==0){
		vol->at_data=type;
		check_type=0x80;
	}else if(ntfs_ua_strncmp(name,"$INDEX_ROOT",64)==0){
		vol->at_index_root=type;
		check_type=0x90;
	}else if(ntfs_ua_strncmp(name,"$INDEX_ALLOCATION",64)==0){
		vol->at_index_allocation=type;
		check_type=0xA0;
	}else if(ntfs_ua_strncmp(name,"$BITMAP",64)==0){
		vol->at_bitmap=type;
		check_type=0xB0;
	}else if(ntfs_ua_strncmp(name,"$SYMBOLIC_LINK",64)==0 ||
		 ntfs_ua_strncmp(name,"$REPARSE_POINT",64)==0){
		vol->at_symlink=type;
		check_type=0xC0;
	}
	if(check_type && check_type!=type){
		ntfs_error("Unexpected type %x for %x\n",type,check_type);
		return EINVAL;
	}
	return 0;
}

int
ntfs_init_attrdef(ntfs_inode* attrdef)
{
	ntfs_u8 *buf;
	ntfs_io io;
	int offset,error,i;
	ntfs_attribute *data;
	buf=ntfs_malloc(4050); /* 90*45 */
	if(!buf)return ENOMEM;
	io.fn_put=ntfs_put;
	io.fn_get=ntfs_get;
	io.do_read=1;
	offset=0;
	data=ntfs_find_attr(attrdef,attrdef->vol->at_data,0);
	if(!data){
		ntfs_free(buf);
		return EINVAL;
	}
	do{
		io.param=buf;
		io.size=4050;
		error=ntfs_readwrite_attr(attrdef,data,offset,&io);
		for(i=0;!error && i<io.size-0xA0;i+=0xA0)
			error=process_attrdef(attrdef,buf+i);
		offset+=4096;
	}while(!error && io.size);
	ntfs_free(buf);
	return error;
}

/* ntfs_get_version will determine the NTFS version of the 
   volume and will return the version in a BCD format, with
   the MSB being the major version number and the LSB the
   minor one. Otherwise return <0 on error. 
   Example: version 3.1 will be returned as 0x0301.
   This has the obvious limitation of not coping with version
   numbers above 0x80 but that shouldn't be a problem... */
int ntfs_get_version(ntfs_inode* volume)
{
	ntfs_attribute *volinfo;

	volinfo = ntfs_find_attr(volume, volume->vol->at_volume_information, 0);
	if (!volinfo) 
		return -EINVAL;
	if (!volinfo->resident) {
		ntfs_error("Volume information attribute is not resident!\n");
		return -EINVAL;
	}
	return ((ntfs_u8*)volinfo->d.data)[8] << 8 | ((ntfs_u8*)volinfo->d.data)[9];
}

int ntfs_load_special_files(ntfs_volume *vol)
{
	int error;
	ntfs_inode upcase, attrdef, volume;

	vol->mft_ino=(ntfs_inode*)ntfs_calloc(3*sizeof(ntfs_inode));
	error=ENOMEM;
	ntfs_debug(DEBUG_BSD,"Going to load MFT\n");
	if(!vol->mft_ino || (error=ntfs_init_inode(vol->mft_ino,vol,FILE_MFT)))
	{
		ntfs_error("Problem loading MFT\n");
		return error;
	}
	ntfs_debug(DEBUG_BSD,"Going to load MIRR\n");
	vol->mftmirr=vol->mft_ino+1;
	if((error=ntfs_init_inode(vol->mftmirr,vol,FILE_MFTMIRR))){
		ntfs_error("Problem %d loading MFTMirr\n",error);
		return error;
	}
	ntfs_debug(DEBUG_BSD,"Going to load BITMAP\n");
	vol->bitmap=vol->mft_ino+2;
	if((error=ntfs_init_inode(vol->bitmap,vol,FILE_BITMAP))){
		ntfs_error("Problem loading Bitmap\n");
		return error;
	}
	ntfs_debug(DEBUG_BSD,"Going to load UPCASE\n");
	error=ntfs_init_inode(&upcase,vol,FILE_UPCASE);
	if(error)return error;
	ntfs_init_upcase(&upcase);
	ntfs_clear_inode(&upcase);
	ntfs_debug(DEBUG_BSD,"Going to load ATTRDEF\n");
	error=ntfs_init_inode(&attrdef,vol,FILE_ATTRDEF);
	if(error)return error;
	error=ntfs_init_attrdef(&attrdef);
	ntfs_clear_inode(&attrdef);
	if(error)return error;

	/* Check for NTFS version and if Win2k version (ie. 3.0+)
	   do not allow write access since the driver write support
	   is broken, especially for Win2k. */
	ntfs_debug(DEBUG_BSD,"Going to load VOLUME\n");
	error = ntfs_init_inode(&volume,vol,FILE_VOLUME);
	if (error) return error;
	if ((error = ntfs_get_version(&volume)) >= 0x0300) {
		NTFS_SB(vol)->s_flags |= MS_RDONLY;
		ntfs_error("Warning! NTFS volume version is Win2k+: Mounting read-only\n");
	}
	ntfs_clear_inode(&volume);
	if (error < 0) return error;
	ntfs_debug(DEBUG_BSD, "NTFS volume is version %d.%d\n", error >> 8, error & 0xff);

	return 0;
}

int ntfs_release_volume(ntfs_volume *vol)
{
	if(vol->mft_ino){
		ntfs_clear_inode(vol->mft_ino);
		ntfs_clear_inode(vol->mftmirr);
		ntfs_clear_inode(vol->bitmap);
		ntfs_free(vol->mft_ino);
		vol->mft_ino=0;
	}
	ntfs_free(vol->mft);
	ntfs_free(vol->upcase);
	return 0;
}

/*
 * Writes the volume size into vol_size. Returns 0 if successful
 * or error.
 */
int ntfs_get_volumesize(ntfs_volume *vol, ntfs_u64 *vol_size )
{
	ntfs_io io;
	char *cluster0;