path: root/qemu/roms/openbios/fs/grubfs/fsys_ntfs.c

/* vim: set sw=4 :*/
/*
 *  GRUB  --  GRand Unified Bootloader
 *  Copyright (C) 1999  Free Software Foundation, Inc.
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
 *  MA 02110-1301, USA.
 */

/*
 * Samuel Leo <samuel@_.remove.me._szonline.net>
 * Limitations:
 * 1. Only 32 bit size support
 * 2. don't support >1k MFT record size, >16k INDEX record size
 * 3. don't support recursive at_attribute_list
 * 4. don't support compressed attribute other than Datastream
 * 5. all MFT's at_attribute_list must resident at first run list
 * 6. don't support journaling
 * 7. don't support EFS encryption
 * 8. don't support mount point and junction
 */
#ifdef FSYS_NTFS

//#define DEBUG_NTFS 1

/*
#define NO_ATTRIBUTE_LIST 1
   totally disable at_attribute_list support,
   if no compressed/fragment file and MFT,
   not recommended
#define NO_NON_RESIDENT_ATTRIBUTE_LIST 1
   disable non-resident at_attribute_list support,
   if no huge compressed/fragment file and MFT
#define NO_NTFS_DECOMPRESSION 1
   disable ntfs compressed file support
#define NO_ALTERNATE_DATASTREAM 1
   disable ntfs alternate datastream support
*/

#include "shared.h"
#include "filesys.h"

#ifdef STAGE1_5
/* safe turn off non-resident attribute list if MFT fragments < 4000 */
//#define NO_NON_RESIDENT_ATTRIBUTE_LIST 1
#define NO_NTFS_DECOMPRESSION 1
#endif

#define MAX_MFT_RECORD_SIZE 1024
#define MAX_INDEX_RECORD_SIZE 16384
#define MAX_INDEX_BITMAP_SIZE 4096
#define DECOMP_DEST_BUFFER_SIZE 16384
#define DECOMP_SOURCE_BUFFER_SIZE (8192+2)
#define MAX_DIR_DEPTH 64

/* sizes are always in bytes, BLOCK values are always in DEV_BSIZE (sectors) */
#define DEV_BSIZE 512

/* include/linux/fs.h */
#define BLOCK_SIZE 	512

#define WHICH_SUPER 1
#define SBLOCK (WHICH_SUPER * BLOCK_SIZE / DEV_BSIZE)	/* = 2 */

/* include/asm-i386/type.h */
typedef __signed__ char __s8;
typedef unsigned char __u8;
typedef __signed__ short __s16;
typedef unsigned short __u16;
typedef __signed__ int __s32;
typedef unsigned int __u32;
typedef __signed__ long long __s64;
typedef unsigned long long __u64;

#define FILE_MFT      0
#define FILE_MFTMIRR  1
#define FILE_LOGFILE  2
#define FILE_VOLUME   3
#define FILE_ATTRDEF  4
#define FILE_ROOT     5
#define FILE_BITMAP   6
#define FILE_BOOT     7
#define FILE_BADCLUS  8
#define FILE_QUOTA    9
#define FILE_UPCASE  10

#define at_standard_information 0x10
#define at_attribute_list 	0x20
#define at_filename		0x30
#define at_security_descriptor	0x50
#define at_data			0x80
#define at_index_root		0x90
#define at_index_allocation	0xa0
#define at_bitmap		0xb0
#define at_symlink		0xc0

#define NONAME	""
#define ATTR_NORMAL	0
#define ATTR_COMPRESSED	1
#define ATTR_RESIDENT	2
#define ATTR_ENCRYPTED	16384
#define ATTR_SPARSE	32768

typedef struct run_list {
	char *start;
	char *ptr;
	int svcn;
	int evcn;
	int vcn;
	int cnum0;
	int cnum;
	int clen;
} RUNL;

typedef struct ntfs_mft_record {
	char mft[MAX_MFT_RECORD_SIZE];
	char mft2[MAX_MFT_RECORD_SIZE];
	int attr_type;
	char *attr_name;
	int attr_flag;
	int attr_size;
	char *attr;
	int attr_len;
	RUNL runl;
	char *attr_list;
	int attr_list_len;
	int attr_list_size;
	int attr_list_off;
	int attr_inited;
	char attr_list_buf[2*BLOCK_SIZE];
	RUNL attr_list_runl;
} MFTR;


#define index_data	((char *)FSYS_BUF)
#define bitmap_data	((__u8 *)(FSYS_BUF+MAX_INDEX_RECORD_SIZE))
#define dcdbuf	((__u8 *)index_data)
#define dcsbuf	(bitmap_data)
#define dcend	(dcsbuf+DECOMP_SOURCE_BUFFER_SIZE)
#define fnbuf ((char *)(bitmap_data+MAX_INDEX_BITMAP_SIZE))
#define mmft	((MFTR *)dcend)
#define cmft	((MFTR *)(dcend+sizeof(MFTR)))
#define mft_run	((RUNL *)(dcend+2*sizeof(MFTR)))
#define path_ino ((int *)(dcend+2*sizeof(MFTR)+sizeof(RUNL)))
#define cluster16 (path_ino+MAX_DIR_DEPTH)
#define index16 cluster16[16]
#define blocksize cluster16[17]
#define clustersize cluster16[18]
#define mft_record_size cluster16[19]
#define index_record_size cluster16[20]
#define dcvcn cluster16[21]
#define dcoff cluster16[22]
#define dclen cluster16[23]
#define dcrem cluster16[24]
#define dcslen cluster16[25]
#define dcsptr ((__u8 *)cluster16[26])
#define is_ads_completion cluster16[27]

static int read_mft_record(int mftno, char *mft, int self);
static int read_attribute(MFTR *mftr, int offset, char *buf, int len, RUNL *from_rl);
static int get_next_run(RUNL *runl);

static inline int
nsubstring (char *s1, char *s2)
{
    while (tolower(*s1) == tolower(*s2))
    {
	/* The strings match exactly. */
	if (! *(s1++))
	    return 0;
	s2 ++;
    }

    /* S1 is a substring of S2. */
    if (*s1 == 0)
	return -1;

    /* S1 isn't a substring. */
    return 1;
}

static int fixup_record(char *record, char *magic, int size)
{
    int start, count, offset;
    __u16 fixup;

    if(*(int *)record != *(int *)magic)
	return 0;
    start=*(__u16 *)(record+4);
    count=*(__u16 *)(record+6);
    count--;
    if(size && blocksize*count != size)
	return 0;
    fixup = *(__u16 *)(record+start);
    start+=2;
    offset=blocksize-2;
    while(count--){
	if(*(__u16 *)(record+offset)!=fixup)
	    return 0;
	*(__u16 *)(record+offset) = *(__u16 *)(record+start);
	start+=2;
	offset+=blocksize;
    }
    return 1;
}

static void rewind_run_list( RUNL *runl) {
    runl->vcn = runl->svcn;
    runl->ptr = runl->start;
    runl->cnum0 = 0;
    runl->cnum = 0;
    runl->clen = 0;
}

static int get_next_run(RUNL *runl){
    int t, n, v;

#ifdef DEBUG_NTFS
    printf("get_next_run: s=%d e=%d c=%d start=%x ptr=%x\n",
	   runl->svcn, runl->evcn, runl->vcn, runl->start, runl->ptr);
#endif

    runl->vcn += runl->clen;
    if(runl->vcn > runl->evcn) {
    	return 0;
    }

    t = *(runl->ptr)++;
    n = t&0xf;
    runl->clen = 0; v = 1;
    while(n--) {
	runl->clen += v * *((__u8 *)runl->ptr)++;
	v <<= 8;
    }
    n = (t>>4)&0xf;
    if(n==0)
	runl->cnum = 0;
    else {
	int c = 0;
	v = 1;
	while(n--) {
	    c += v * *((__u8 *)runl->ptr)++;
	    v <<= 8;
	}
	if(c & (v>>1)) c -= v;
	runl->cnum0 += c;
	runl->cnum = runl->cnum0;
    }
#ifdef DEBUG_NTFS
    printf("got_next_run: t=%x cluster %x len %x vcn=%x ecn=%x\n",
    	t, runl->cnum, runl->clen, runl->vcn, runl->evcn);
#endif
    return 1;
}

#ifndef NO_ATTRIBUTE_LIST
static void init_run_list(char *attr, int len, RUNL *runl, __u32 *initp) {
    int allocated;

    runl->svcn = *(__u32 *)(attr+0x10); /* only support 32 bit */
    runl->evcn = *(__u32 *)(attr+0x18); /* only support 32 bit */
    runl->start = attr + *(__u16 *)(attr+0x20);
    allocated = *(__u32 *)(attr+0x28);
    if(initp) *initp = *(__u32 *)(attr+0x38);
    if(!runl->evcn) runl->evcn = (allocated - 1) / clustersize;
#ifdef DEBUG_NTFS
    printf("size %d allocated=%d inited=%d cegin=%x csize=%d vcn=%d-%d\n",
	    /*attr_size*/ *(__u32 *)(attr+0x30),
	    /*allocated*/ *(__u32 *)(attr+0x28),
	    /*attr_inited*/ *(__u32 *)(attr+0x38),
	    /*cengin*/ *(__u16 *)(attr+0x22),
	    /*csize*/ *(__u16 *)(attr+0x40),
	    runl->svcn, runl->evcn);
#endif
    rewind_run_list(runl);
}
#endif


static int find_attribute(char *mft, int type, char *name, char **attr, int *size, int *len, int *flag) {
    int t, l, r, n, i, namelen;
    unsigned short *attr_name;

    n = strlen(name);
    r = mft_record_size - *(__u16 *)(mft+0x14);
    mft += *(__u16 *)(mft+0x14);
    while( (t = *(__s32 *)mft) != -1 ) {
	l = *(__u32 *)(mft+4);
	if(l>r) break;
#ifdef DEBUG_NTFS
	printf("type = %x len = %d namelen=%d resident=%d compresed=%d attrno=%d\n",
		t, l,
		/*namelen*/ *(mft+9),
		//name = (__u16 *)(mft + *(__u16 *)(mft+10)),
		/*resident */ (*(mft+8) == 0),
		/*compressed*/ *(__u16 *)(mft+12),
		/*attrno*/ *(__u16 *)(mft+14));
#endif
	namelen = *(mft+9);
	if(t == type) {
#ifndef STAGE1_5
#ifndef NO_ALTERNATE_DATASTREAM
	    if(is_ads_completion && type == at_data) {
		if(namelen && namelen >= n &&
		   (!*(mft+8)/*resident*/ || !*(__u32 *)(attr+0x10)/*svcn==0*/))
		{
		    for(i=0, attr_name=(__u16 *)(mft + *(__u16 *)(mft+10)); i < n; i++)
			if(tolower(name[i]) != tolower(attr_name[i]))
			    break;
		    if(i >= n) {
			for(; i < namelen; i++)
			    name[i] = attr_name[i];
			name[i] = '\0';
			if(print_possibilities > 0)
			    print_possibilities = -print_possibilities;
			print_a_completion(fnbuf);
			name[n] = '\0';
		    }
		}
	    } else
#endif
#endif
		if(namelen == n) {

		for(i=0, attr_name=(__u16 *)(mft + *(__u16 *)(mft+10)); i<n; i++)
		    if(tolower(name[i]) != tolower(attr_name[i]))
			break;
		if(i>=n) {
		    if(flag) *flag = *(__u16 *)(mft+12);
		    if(*(mft+8) == 0) {
			if(flag) *flag |= ATTR_RESIDENT;
#ifdef DEBUG_NTFS
			printf("resident data at %x size %x indexed=%d\n",
			       /*data*/ *(__u16 *)(mft+0x14),
			       /*attr_size*/ *(__u16 *)(mft+0x10),
			       /*indexed*/ *(__u16 *)(mft+0x16));
#endif
			if(attr) *attr = mft + *(__u16 *)(mft+0x14);
			if(size) *size = *(__u16 *)(mft+0x10);
			if(len) *len = *(__u16 *)(mft+0x10);
		    } else {
			if(attr) *attr = mft;
			if(size) *size = *(__u32 *)(mft+0x30);
			if(len) *len = l;
		    }
		    return 1;
		}
	    }
	}
	mft += l;
	r -= l;
    }
    return 0;
}

#ifndef NO_ATTRIBUTE_LIST
static __u32 get_next_attribute_list(MFTR *mftr, int *size) {
    int l, t, mftno;
#ifdef DEBUG_NTFS
    printf("get_next_attribute_list: type=%x\n",mftr->attr_type);
#endif
again:
    while(mftr->attr_list_len>0x14) {
	t = *(__u32 *)(mftr->attr_list + 0);
	l = *(__u16 *)(mftr->attr_list + 4);
#ifdef DEBUG_NTFS
	printf("attr_list type=%x len=%x remain=%x\n", t, l, mftr->attr_list_len);
#endif
	if(l==0 || l>mftr->attr_list_len) return 0;
	mftno = *(__u32 *)(mftr->attr_list + 0x10);
	mftr->attr_list_len -= l;
	mftr->attr_list += l;
	if(t==mftr->attr_type)
	{
#ifdef DEBUG_NTFS
	printf("attr_list mftno=%x\n", mftno);
#endif
	    if(read_mft_record(mftno, mftr->mft2, (mftr==mmft))==0)
		break;
	    if(find_attribute(mftr->mft2, mftr->attr_type, mftr->attr_name,
			&mftr->attr, size, &mftr->attr_len, &mftr->attr_flag))
		return 1;
	}
    }
#ifndef NO_NON_RESIDENT_ATTRIBUTE_LIST
    if(mftr->attr_list_off < mftr->attr_list_size) {
	int len = mftr->attr_list_size - mftr->attr_list_off;
	if(len > BLOCK_SIZE) len = BLOCK_SIZE;

	if(mftr->attr_list_len)
	    memmove(mftr->attr_list_buf, mftr->attr_list, mftr->attr_list_len);
	mftr->attr_list = mftr->attr_list_buf;

	if(read_attribute( NULL, mftr->attr_list_off,
			mftr->attr_list_buf + mftr->attr_list_len,
			len, &mftr->attr_list_runl) != len)
	{
#ifdef DEBUG_NTFS
	    printf("CORRUPT NON-RESIDENT ATTRIBUTE_LIST\n");
#endif
	    /* corrupt */
	    errnum = ERR_FSYS_CORRUPT;
	    mftr->attr_list_size = 0;
	    mftr->attr_len = 0;
	    mftr->attr_list = NULL;
	    return 0;
	}

	mftr->attr_list_len += len;
	mftr->attr_list_off += len;
	goto again;
    }
#endif
    mftr->attr_list = NULL;
    return 0;
}
#endif

static int search_attribute( MFTR *mftr, int type, char *name)
{
#ifdef DEBUG_NTFS
    printf("searching attribute %x <%s>\n", type, name);
#endif

    mftr->attr_type = type;
    mftr->attr_name = name;
    mftr->attr_list = NULL;
    mftr->attr_list_len = 0;
    mftr->attr_list_size = 0;
    mftr->attr_list_off = 0;
    dcrem = dclen = 0;

#ifndef NO_ATTRIBUTE_LIST
    if(find_attribute(mftr->mft, at_attribute_list, NONAME,
		      &mftr->attr_list, &mftr->attr_list_size,
		      &mftr->attr_list_len, &mftr->attr_list_off)) {
	if(mftr->attr_list_off&ATTR_RESIDENT) {
	    /* resident at_attribute_list */
	    mftr->attr_list_size = 0;
#ifdef DEBUG_NTFS
	    printf("resident attribute_list len=%x\n", mftr->attr_list_len);
#endif
	} else {
#ifdef DEBUG_NTFS
	    printf("non-resident attribute_list len=%x size=%x\n",
		   mftr->attr_list_len, mftr->attr_list_size);
#endif
#ifndef NO_NON_RESIDENT_ATTRIBUTE_LIST
	    init_run_list(mftr->attr_list, mftr->attr_list_len, &mftr->attr_list_runl, NULL);
	    if(get_next_run(&mftr->attr_list_runl)==0 ||
	       mftr->attr_list_runl.cnum==0)
		mftr->attr_list_size = 0;
#endif
	    mftr->attr_list = NULL;
	    mftr->attr_list_len = 0;
	}
    }
#endif

    if(find_attribute(mftr->mft, type, name,
		      &mftr->attr, &mftr->attr_size, &mftr->attr_len,
		      &mftr->attr_flag)
#ifndef NO_ATTRIBUTE_LIST
       || get_next_attribute_list(mftr, &mftr->attr_size)
#endif
       )
    {
#ifndef NO_ATTRIBUTE_LIST
	if(!(mftr->attr_flag&ATTR_RESIDENT)){
	    init_run_list(mftr->attr, mftr->attr_len, &mftr->runl, &mftr->attr_inited);
	    if(mftr->attr_inited > mftr->attr_size)
	    	mftr->attr_inited = mftr->attr_size;
	    if(get_next_run(&mftr->runl)==0) {
		mftr->attr_flag |= ATTR_RESIDENT;
		mftr->attr_len = 0;
	    }
	} else
	    mftr->attr_inited = mftr->attr_size;
#endif

	return 1;
    }

    mftr->attr_type = 0;
    return 0;
}

static int get_run( RUNL *rl, int vcn, int *clp, int *lenp) {
    if(rl->evcn < vcn)
	return 0;

    if(rl->vcn > vcn) {
    	rewind_run_list(rl);
	get_next_run(rl);
    }

    while(rl->vcn+rl->clen <= vcn)
    {
	if(get_next_run(rl)==0)
	    return 0;
    }

    if(clp) *clp = rl->cnum == 0 ? 0 : rl->cnum + vcn - rl->vcn;
    if(lenp) *lenp = rl->clen - vcn + rl->vcn;
    return 1;
}

static int search_run(MFTR *mftr, int vcn) {

    if( mftr->attr==NULL && !search_attribute(mftr, mftr->attr_type, mftr->attr_name))
	return 0;

    if(mftr->runl.svcn > vcn)
	search_attribute(mftr, mftr->attr_type, mftr->attr_name);

#ifdef NO_ATTRIBUTE_LIST
    if(mftr->runl.evcn < vcn)
	return 0;
#else
    while(mftr->runl.evcn < vcn) {
	if(get_next_attribute_list(mftr, NULL)==0) {
	    mftr->attr = NULL;
	    return 0;
	}
	init_run_list(mftr->attr, mftr->attr_len, &mftr->runl, NULL);
	if(get_next_run(&mftr->runl)==0) {
	    mftr->attr = NULL;
	    return 0;
	}
    }
#endif

    return 1;
}

static int read_attribute(MFTR *mftr, int offset, char *buf, int len, RUNL *from_rl) {
    int vcn;
    int cnum, clen;
    int done = 0;
    int n;
    RUNL *rl;

    if(!from_rl && (mftr->attr_flag & ATTR_RESIDENT)) {
	/* resident attribute */
	if(offset > mftr->attr_len)
	    return 0;
	if(offset+len > mftr->attr_len)
	    len = mftr->attr_len - offset;
	memmove( buf, mftr->attr + offset, len);
	return len;
    }

    vcn = offset / clustersize;
    offset %= clustersize;

    while(len>0) {
	if(from_rl)
	    rl = from_rl;
	else if(search_run(mftr, vcn) == 0)
	    break;
	else
	    rl = &mftr->runl;
	if(get_run(rl, vcn, &cnum, &clen) == 0)
	    break;
	if(cnum==0 && from_rl)
	    break;
	n = clen * clustersize - offset;
	if(n > len) n = len;
	if(cnum==0) {
	    memset( buf, 0, n);
	} else if(!devread(cnum*(clustersize>>9)+(offset>>9), offset&0x1ff, n, buf))
	    break;

	buf += n;
	vcn += (offset+n)/clustersize;
	done += n;
	offset = 0;
	len -= n;
    }
    return done;
}

static int read_mft_record(int mftno, char *mft, int self){
#ifdef DEBUG_NTFS
    printf("Reading MFT record: mftno=%d\n", mftno);
#endif
    if( read_attribute( mmft, mftno * mft_record_size,
	    mft, mft_record_size, self?mft_run:NULL) != mft_record_size)
	return 0;
    if(!fixup_record( mft, "FILE", mft_record_size))
	return 0;
    return 1;
}

#ifndef NO_NTFS_DECOMPRESSION
static int get_16_cluster(MFTR *mftr, int vcn) {
    int n = 0, cnum, clen;
    while(n < 16 && search_run(mftr, vcn) && get_run(&mftr->runl, vcn, &cnum, &clen) && cnum) {
	if(clen > 16 - n)
	    clen = 16 - n;
	vcn += clen;
	while(clen--)
	    cluster16[n++] = cnum++;
    }
    cluster16[n] = 0;
    return n;
}

static inline int compressed_block_size( unsigned char *src ) {
    return 3 + (*(__u16 *)src & 0xfff);
}

static int decompress_block(unsigned char *dest, unsigned char *src) {
    int head;
    int copied=0;
    unsigned char *last;
    int bits;
    int tag=0;

    /* high bit indicates that compression was performed */
    if(!(*(__u16 *)src & 0x8000)) {
	memmove(dest,src+2,0x1000);
	return 0x1000;
    }

    if((head = *(__u16 *)src & 0xFFF)==0)
	/* block is not used */
	return 0;

    src += 2;
    last = src+head;
    bits = 0;

    while(src<=last)
    {
	if(copied>4096)
	{
#ifdef DEBUG_NTFS
	    printf("decompress error 1\n");
#endif
	    errnum = ERR_FSYS_CORRUPT;
	    return 0;
	}
	if(!bits){
	    tag=*(__u8 *)src;
	    bits=8;
	    src++;
	    if(src>last)
		break;
	}
	if(tag & 1){
	    int i,len,delta,code,lmask,dshift;
	    code = *(__u16 *)src;
	    src+=2;
	    if(!copied)
	    {
#ifdef DEBUG_NTFS
		printf("decompress error 2\n");
#endif
		errnum = ERR_FSYS_CORRUPT;
		return 0;
	    }
	    for(i=copied-1,lmask=0xFFF,dshift=12;i>=0x10;i>>=1)
	    {
		lmask >>= 1;
		dshift--;
	    }
	    delta = code >> dshift;
	    len = (code & lmask) + 3;
	    for(i=0; i<len; i++)
	    {
		dest[copied]=dest[copied-delta-1];
		copied++;
	    }
	} else
	    dest[copied++]=*(__u8 *)src++;
	tag>>=1;
	bits--;
    }

    return copied;
}
#endif

int ntfs_read(char *buf, int len){
    int ret;
#ifdef STAGE1_5
/* stage2 can't be resident/compressed/encrypted files,
 * but does sparse flag, cause stage2 never sparsed
 */
    if((cmft->attr_flag&~ATTR_SPARSE) != ATTR_NORMAL)
	return 0;
    disk_read_func = disk_read_hook;
    ret = read_attribute(cmft, filepos, buf, len, 0);
    disk_read_func = NULL;
    filepos += ret;
#else

#ifndef NO_NTFS_DECOMPRESSION
    int off;
    int vcn;
    int size;
    int len0;
#endif

    if(len<=0 || filepos >= cmft->attr_size || (cmft->attr_flag&ATTR_ENCRYPTED))
	return 0;

    if(filepos+len > cmft->attr_size)
	len = cmft->attr_size - filepos;
    if(filepos >= cmft->attr_inited) {
#ifdef DEBUG_NTFS
printf("reading uninitialized data 1\n");
#endif
    	memset(buf, 0, len);
	return len;
    } else if(filepos+len > cmft->attr_inited) {
    	len0 = len;
	len = cmft->attr_inited - filepos;
	len0 -= len;
    } else
    	len0 = 0;
#ifdef DEBUG_NTFS
printf("read filepos=%x filemax=%x inited=%x len=%x len0=%x\n",filepos,filemax,cmft->attr_inited,len,len0);
#endif

    if((cmft->attr_flag&(ATTR_COMPRESSED|ATTR_RESIDENT)) != ATTR_COMPRESSED) {
	if(cmft->attr_flag==ATTR_NORMAL)
	    disk_read_func = disk_read_hook;
	ret = read_attribute(cmft, filepos, buf, len, 0);
	if(cmft->attr_flag==ATTR_NORMAL)
	    disk_read_func = NULL;
	filepos += ret;
	if(ret==len && len0) {
		memset(buf+len, 0, len0);
		filepos += len0;
		ret += len0;
	}
	return ret;
    }

    ret = 0;

#ifndef NO_NTFS_DECOMPRESSION
    /* NTFS don't support compression if cluster size > 4k */
    if(clustersize > 4096) {
	errnum = ERR_FSYS_CORRUPT;
	return 0;
    }

    while(len > 0){
#ifdef DEBUG_NTFS
printf("Reading filepos=%x len=%x\n", filepos, len);
#endif
	if(filepos >= dcoff && filepos < (dcoff+dclen)) {
#ifdef DEBUG_NTFS
printf("decompress cache %x+%x\n", dcoff, dclen);
#endif
	    size = dcoff + dclen - filepos;
	    if(size > len) size = len;
	    memmove( buf, dcdbuf + filepos - dcoff, size);
	    filepos += size;
	    len -= size;
	    ret += size;
	    buf += size;
	    if(len==0) {
		if(len0) {
#ifdef DEBUG_NTFS
printf("reading uninitialized data 2\n");
#endif
		    memset(buf, 0, len0);
		    filepos += len0;
		    ret += len0;
		}
		return ret;
	    }
	}

	vcn = filepos / clustersize / 16;
	vcn *= 16;
	off = filepos % (16 * clustersize);
	if( dcvcn != vcn || filepos < dcoff)
	    dcrem = 0;

#ifdef DEBUG_NTFS
printf("vcn %x off %x dcrem %x\n", vcn, off, dcrem);
#endif
	if(dcrem) {
	    int head;

	    /* reading source */
	    if(dcslen < 2 || compressed_block_size(dcsptr) > dcslen) {
		if(cluster16[index16]==0) {
		    errnum = ERR_FSYS_CORRUPT;
		    return ret;
		}
		if(dcslen)
		    memmove(dcsbuf, dcsptr, dcslen);
		dcsptr = dcsbuf;
		while((dcslen+clustersize) < DECOMP_SOURCE_BUFFER_SIZE) {
		    if(cluster16[index16]==0)
			break;
#ifdef DEBUG_NTFS
printf("reading dcslen=%x cluster %x\n", dcslen, cluster16[index16]);
#endif
		    if(!devread(cluster16[index16]*(clustersize>>9), 0, clustersize, dcsbuf+dcslen))
			return ret;
		    dcslen += clustersize;
		    index16++;
		}
	    }
	    /* flush destination */
	    dcoff += dclen;
	    dclen = 0;

	    while(dcrem && dclen < DECOMP_DEST_BUFFER_SIZE &&
		  dcslen >= 2 && (head=compressed_block_size(dcsptr)) <= dcslen) {
		size = decompress_block(dcdbuf+dclen, dcsptr);
		if(dcrem>=0x1000 && size!=0x1000) {
		    errnum = ERR_FSYS_CORRUPT;
		    return ret;
		}
		dcrem -= size;
		dclen += size;
		dcsptr += head;
		dcslen -= head;
	    }
	    continue;
	}
	dclen = dcrem = 0;
#ifdef DEBUG_NTFS
printf("get next 16 clusters\n");
#endif
	switch(get_16_cluster(cmft, vcn)) {
	case 0:
#ifdef DEBUG_NTFS
printf("sparse\n");
#endif
	    /* sparse */
	    size = 16 * clustersize - off;
	    if( len < size )
		size = len;
#ifndef STAGE1_5
	    memset( buf, 0, size);
#endif
	    filepos += size;
	    len -= size;
	    ret += size;
	    buf += size;
	    break;

	case 16:
#ifdef DEBUG_NTFS
printf("uncompressed\n");
#endif
	    /* uncompressed */
	    index16 = off / clustersize;
	    off %= clustersize;
	    while(index16 < 16) {
		size = clustersize - off;
		if( len < size )
		    size = len;
		if(!devread(cluster16[index16]*(clustersize>>9)+(off>>9), off&0x1ff, size, buf))
		    return ret;
		filepos += size;
		len -= size;
		ret += size;
		if(len==0)
		    return ret;
		off = 0;
		buf += size;
		index16++;
	    }
	    break;

	default:
#ifdef DEBUG_NTFS
printf("compressed\n");
#endif
	    index16 = 0;
	    dcvcn = vcn;
	    dcoff = vcn * clustersize;
	    dcrem = cmft->attr_inited - dcoff;
	    if(dcrem > 16 * clustersize)
		dcrem = 16 * clustersize;
	    dcsptr = dcsbuf;
	    dcslen = 0;
	}
    }
    if(len0) {
#ifdef DEBUG_NTFS
printf("reading uninitialized data 3\n");
#endif
	memset(buf, 0, len0);
	filepos += len0;
	ret += len0;
    }
#else
    errnum = FSYS_CORRUPT;
#endif /*NO_NTFS_DECOMPRESSION*/
#endif /*STAGE1_5*/
    return ret;
}

int ntfs_mount (void)
{
    char *sb = (char *)FSYS_BUF;
    int mft_record;
    int spc;

  if (((current_drive & 0x80) || (current_slice != 0))
       && (current_slice != /*PC_SLICE_TYPE_NTFS*/7)
       && (current_slice != /*PC_SLICE_TYPE_NTFS*/0x17))
      return 0;

    if (!devread (0, 0, 512, (char *) FSYS_BUF))
	return 0;			/* Cannot read superblock */

    if(sb[3]!='N' || sb[4]!='T' || sb[5]!='F' || sb[6]!='S')
	return 0;
    blocksize = *(__u16 *)(sb+0xb);
    spc = *(unsigned char *)(sb+0xd);
    clustersize = spc * blocksize;
    mft_record_size = *(char *)(sb+0x40);
    index_record_size = *(char *)(sb+0x44);
    if(mft_record_size>0)
	mft_record_size *= clustersize;
    else
	mft_record_size = 1 << (-mft_record_size);

    index_record_size *= clustersize;
    mft_record = *(__u32 *)(sb+0x30); /* only support 32 bit */
    spc = clustersize / 512;

    if(mft_record_size > MAX_MFT_RECORD_SIZE || index_record_size > MAX_INDEX_RECORD_SIZE) {
	/* only support 1k MFT record, 4k INDEX record */
	return 0;
    }

#ifdef DEBUG_NTFS
    printf("spc=%x mft_record=%x:%x\n", spc, *(__s64 *)(sb+0x30));
#endif

    if (!devread (mft_record*spc, 0, mft_record_size, mmft->mft))
	return 0;			/* Cannot read superblock */

    if(!fixup_record( mmft->mft, "FILE", mft_record_size))
	return 0;

#ifndef NO_ALTERNATE_DATASTREAM
    is_ads_completion = 0;
#endif
    if(!search_attribute(mmft, at_data, NONAME)) return 0;

    *mft_run = mmft->runl;

    *path_ino = FILE_ROOT;

    return 1;
}

int
ntfs_dir (char *dirname)
{
    char *rest, ch;
    int namelen;
    int depth = 0;
    int chk_sfn = 1;
    int flag = 0;
    int record_offset;
    int my_index_record_size;
    unsigned char *index_entry = 0, *entry, *index_end;
    int i;

    /* main loop to find desired directory entry */
loop:

#ifdef DEBUG_NTFS
    printf("dirname=%s\n", dirname);
#endif
    if(!read_mft_record(path_ino[depth], cmft->mft, 0))
    {
#ifdef DEBUG_NTFS
	printf("MFT error 1\n");
#endif
	errnum = ERR_FSYS_CORRUPT;
	return 0;
    }

    /* if we have a real file (and we're not just printing possibilities),
       then this is where we want to exit */

    if (!*dirname || isspace (*dirname) || *dirname==':')
    {
#ifndef STAGE1_5
#ifndef NO_ALTERNATE_DATASTREAM
	if (*dirname==':' && print_possibilities) {
	    char *tmp;

	    /* preparing ADS name completion */
	    for(tmp = dirname; *tmp != '/'; tmp--);
	    for(tmp++, rest=fnbuf; *tmp && !isspace(*tmp); *rest++ = *tmp++)
		if(*tmp==':') dirname = rest;
	    *rest++ = '\0';

	    is_ads_completion = 1;
	    search_attribute(cmft, at_data, dirname+1);
	    is_ads_completion = 0;

	    if(errnum==0) {
		if(print_possibilities < 0)
		    return 1;
		errnum = ERR_FILE_NOT_FOUND;
	    }
	    return 0;
	}
#endif
#endif

	if (*dirname==':') dirname++;
	for (rest = dirname; (ch = *rest) && !isspace (ch); rest++);
	*rest = 0;

#ifdef DEBUG_NTFS
	printf("got file: search at_data\n");
#endif

	if (!search_attribute(cmft, at_data, dirname)) {
	    errnum = *(dirname-1)==':'?ERR_FILE_NOT_FOUND:ERR_BAD_FILETYPE;
	    *rest = ch;
	    return 0;
	}
	*rest = ch;

	filemax = cmft->attr_size;
#ifdef DEBUG_NTFS
	printf("filemax=%x\n", filemax);
#endif
	return 1;
    }

    if(depth >= (MAX_DIR_DEPTH-1)) {
	errnum = ERR_FSYS_CORRUPT;
	return 0;
    }

    /* continue with the file/directory name interpretation */

    while (*dirname == '/')
	dirname++;

    for (rest = dirname; (ch = *rest) && !isspace (ch) && ch != '/' && ch != ':'; rest++);

    *rest = 0;

    if (!search_attribute(cmft, at_index_root, "$I30"))
    {
	errnum = ERR_BAD_FILETYPE;
	return 0;
    }

    read_attribute(cmft, 0, fnbuf, 16, 0);
    my_index_record_size = *(__u32 *)(fnbuf+8);

    if(my_index_record_size > MAX_INDEX_RECORD_SIZE) {
	errnum = ERR_FSYS_CORRUPT;
	return 0;
    }

#ifdef DEBUG_NTFS
    printf("index_record_size=%x\n", my_index_record_size);
#endif

    if(cmft->attr_size > MAX_INDEX_RECORD_SIZE) {
	errnum = ERR_FSYS_CORRUPT;
	return 0;
    }
    read_attribute(cmft, 0, index_data, cmft->attr_size, 0);
    index_end = index_data + cmft->attr_size;
    index_entry = index_data + 0x20;
    record_offset = -1;

#ifndef STAGE1_5
    if (print_possibilities && ch != '/' && ch != ':' && !*dirname)
    {
	print_possibilities = -print_possibilities;
	/* fake '.' for empty directory */
	print_a_completion (".");
    }
#endif

    if (search_attribute(cmft, at_bitmap, "$I30")) {
	if(cmft->attr_size > MAX_INDEX_BITMAP_SIZE) {
	    errnum = ERR_FSYS_CORRUPT;
	    return 0;
	}

	read_attribute(cmft, 0, bitmap_data, cmft->attr_size, 0);

	if (search_attribute(cmft, at_index_allocation, "$I30")==0) {
	    errnum = ERR_FSYS_CORRUPT;
	    return 0;
	}

	for(record_offset = 0; record_offset*my_index_record_size<cmft->attr_size; record_offset++){
	    int bit = 1 << (record_offset&3);
	    int byte = record_offset>>3;
#ifdef DEBUG_NTFS
	    printf("record_offset=%x\n", record_offset);
#endif
	    if((bitmap_data[byte]&bit))
		break;
	}

	if(record_offset*my_index_record_size>=cmft->attr_size) record_offset = -1;
    }

    do
    {
	entry = index_entry; index_entry += *(__u16 *)(entry+8);
	if(entry+0x50>=index_entry||entry>=index_end||
	   index_entry>=index_end||(entry[0x12]&2)){
	    if(record_offset < 0 ||
	       !read_attribute(cmft, record_offset*my_index_record_size, index_data, my_index_record_size, 0)){
		if (!errnum)
		{
		    if (print_possibilities < 0)
		    {
#if 0
			putchar ('\n');
#endif
			return 1;
		    }

		    errnum = ERR_FILE_NOT_FOUND;
		    *rest = ch;
		}

		return 0;
	    }
	    if(!fixup_record( index_data, "INDX", my_index_record_size))
	    {
#ifdef DEBUG_NTFS
		printf("index error\n");
#endif
		errnum = ERR_FSYS_CORRUPT;
		return 0;
	    }
	    entry = index_data + 0x18 + *(__u16 *)(index_data+0x18);
	    index_entry = entry + *(__u16 *)(entry+8);
	    index_end = index_data + my_index_record_size - 0x52;
	    for(record_offset++; record_offset*my_index_record_size<cmft->attr_size; record_offset++){
		int bit = 1 << (record_offset&3);
		int byte = record_offset>>3;
		if((bitmap_data[byte]&bit)) break;
	    }
	    if(record_offset*my_index_record_size>=cmft->attr_size) record_offset = -1;
#ifdef DEBUG_NTFS
	    printf("record_offset=%x\n", record_offset);
#endif
	}
	flag = entry[0x51];
	path_ino[depth+1] = *(__u32 *)entry;
	if(path_ino[depth+1] < 16)
	    continue;
	namelen = entry[0x50];
	//if(index_data[0x48]&2) printf("hidden file\n");
#ifndef STAGE1_5
	/* skip short file name */
	if( flag == 2 && print_possibilities && ch != '/' && ch != ':' )
	    continue;
#endif

	for( i = 0, entry+=0x52; i < namelen; i++, entry+=2 )
	{
	    int c = *(__u16 *)entry;
	    if(c==' '||c>=0x100)
		fnbuf[i] = '_';
	    else
		fnbuf[i] = c;
	}
	fnbuf[namelen] = 0;
#ifdef DEBUG_NTFS
	printf("FLAG: %d  NAME: %s  inum=%d\n", flag,fnbuf,path_ino[depth+1]);
#endif

	//uncntrl(fnbuf);

	chk_sfn = nsubstring(dirname,fnbuf);
#ifndef STAGE1_5
	if (print_possibilities && ch != '/' && ch != ':'
	    && (!*dirname || chk_sfn <= 0))
	{
	    if (print_possibilities > 0)
		print_possibilities = -print_possibilities;
	    print_a_completion (fnbuf);
	}
#endif /* STAGE1_5 */
    }
    while (chk_sfn != 0 ||
	   (print_possibilities && ch != '/' && ch != ':'));

    *(dirname = rest) = ch;

    depth++;

    /* go back to main loop at top of function */
    goto loop;
}

#ifdef DEBUG_NTFS
int dump_block(char *msg, char *buf, int size){
    int l = (size+15)/16;
    int off;
    int i, j;
    int c;
    printf("----- %s -----\n", msg);
    for( i = 0, off = 0; i < l; i++, off+=16)
    {
	if(off<16)
	    printf("000%x:", off);
	else if(off<256)
	    printf("00%x:", off);
	else
	    printf("0%x:", off);
	for(j=0;j<16;j++)
	{
	    c = buf[off+j]&0xff;
	    if( c >= 16 )
		printf("%c%x",j==8?'-':' ',c);
	    else
		printf("%c0%x",j==8?'-':' ',c);
	}
	printf("  ");
	for(j=0;j<16;j++) {
	    char c = buf[off+j];
	    printf("%c",c<' '||c>='\x7f'?'.':c);
	}
	printf("\n");
    }
}
#endif
#endif /* FSYS_NTFS */