Previous commit broke loading of EFI drivers with SB active; fix it.

[refind] / filesystems / fsw_ntfs.c

/**
 * \file fsw_ntfs.c
 * ntfs file system driver code.
 * Copyright (C) 2015 by Samuel Liao
 */

/*-
 * 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., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
 */

#include "fsw_core.h"

#define Print(x...)     /* */

static inline fsw_u8 GETU8(fsw_u8 *buf, int pos)
{
    return buf[pos];
}

static inline fsw_u16 GETU16(fsw_u8 *buf, int pos)
{
    return fsw_u16_le_swap(*(fsw_u16 *)(buf+pos));
}

static inline fsw_u32 GETU32(fsw_u8 *buf, int pos)
{
    return fsw_u32_le_swap(*(fsw_u32 *)(buf+pos));
}

static inline fsw_u64 GETU64(fsw_u8 *buf, int pos)
{
    return fsw_u64_le_swap(*(fsw_u64 *)(buf+pos));
}

#define MFTMASK  ((1ULL<<48) - 1)
#define BADMFT  (~0ULL)
#define MFTNO_MFT       0
#define MFTNO_VOLUME    3
#define MFTNO_ROOT      5
#define MFTNO_UPCASE    10
#define MFTNO_META      16
#define BADVCN  (~0ULL)

#define AT_STANDARD_INFORMATION 0x10
#define AT_ATTRIBUTE_LIST       0x20
#define AT_FILENAME             0x30    /* UNUSED */
#define AT_VOLUME_NAME          0x60
#define AT_VOLUME_INFORMATION   0x70    /* UNUSED */
#define AT_DATA                 0x80
#define AT_INDEX_ROOT           0x90
#define AT_INDEX_ALLOCATION     0xa0
#define AT_BITMAP               0xb0
#define AT_REPARSE_POINT        0xc0

#define ATTRMASK        0xFFFF
#define ATTRBITS        16
/* $I30 is LE, we can't use L"$I30" */
#define NAME_I30        "$\0I\0003\0000\0"
#define AT_I30          0x40000

static const fsw_u16 upcase[0x80] =
{
    0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a, 0x0b, 0x0c, 0x0d, 0x0e, 0x0f,
    0x10, 0x11, 0x12, 0x13, 0x14, 0x15, 0x16, 0x17, 0x18, 0x19, 0x1a, 0x1b, 0x1c, 0x1d, 0x1e, 0x1f,
    0x20, 0x21, 0x22, 0x23, 0x24, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a, 0x2b, 0x2c, 0x2d, 0x2e, 0x2f,
    0x30, 0x31, 0x32, 0x33, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x3b, 0x3c, 0x3d, 0x3e, 0x3f,
    0x40, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f,
    0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, 0x5b, 0x5c, 0x5d, 0x5e, 0x5f,
    0x60, 0x41, 0x42, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49, 0x4a, 0x4b, 0x4c, 0x4d, 0x4e, 0x4f,
    0x50, 0x51, 0x52, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59, 0x5a, 0x7b, 0x7c, 0x7d, 0x7e, 0x7f,
};

struct extent_slot
{
    fsw_u64 vcn;
    fsw_u64 lcn;
    fsw_u64 cnt;
};

struct extent_map
{
    /*
     * we build mft extent table instead use generic code, to prevent
     * read_mft recursive or dead loop.
     * While mft has too many fragments, it need AT_ATTRIBUTE_LIST for extra
     * data, the AT_ATTRIBUTE_LIST parsing code need call read_mft again.
     */
    struct extent_slot *extent;
    int total;
    int used;
};

struct ntfs_mft
{
    fsw_u64 mftno;              /* current MFT no */
    fsw_u8 *buf;                /* current MFT record data */
    fsw_u8 *atlst;              /* AT_ATTRIBUTE_LIST data */
    int atlen;                  /* AT_ATTRIBUTE_LIST size */
};

struct ntfs_attr
{
    fsw_u64 emftno;             /* MFT no of emft */
    fsw_u8 *emft;               /* cached extend MFT record */
    fsw_u8 *ptr;                /* current attribute data */
    int len;                    /* current attribute size */
    int type;                   /* current attribute type */
};

struct fsw_ntfs_volume
{
    struct fsw_volume g;
    struct extent_map extmap;   /* MFT extent map */
    fsw_u64 totalbytes;         /* volume size */
    const fsw_u16 *upcase;      /* upcase map for non-ascii */
    int upcount;                /* upcase map size */

    fsw_u8 sctbits;             /* sector size */
    fsw_u8 clbits;              /* cluster size */
    fsw_u8 mftbits;             /* MFT record size */
    fsw_u8 idxbits;             /* unused index size, use AT_INDEX_ROOT instead */
};

struct fsw_ntfs_dnode
{
    struct fsw_dnode g;
    struct ntfs_mft mft;
    struct ntfs_attr attr;      /* AT_INDEX_ALLOCATION:$I30/AT_DATA */
    fsw_u8 *idxroot;            /* AT_INDEX_ROOT:$I30 */
    fsw_u8 *idxbmp;             /* AT_BITMAP:$I30 */
    unsigned int embeded:1;     /* embeded AT_DATA */
    unsigned int has_idxtree:1; /* valid AT_INDEX_ALLOCATION:$I30 */
    unsigned int compressed:1;  /* compressed AT_DATA */
    unsigned int unreadable:1;  /* unreadable/encrypted AT_DATA */
    unsigned int cpfull:1;      /* in-compressable chunk */
    unsigned int cpzero:1;      /* empty chunk */
    unsigned int cperror:1;     /* decompress error */
    unsigned int islink:1;      /* is symlink: AT_REPARSE_POINT */
    int idxsz;                  /* size of index block */
    int rootsz;                 /* size of idxroot: AT_INDEX_ROOT:$I30 */
    int bmpsz;                  /* size of idxbmp: AT_BITMAP:$I30 */
    struct extent_slot cext;    /* cached extent */
    fsw_u64 fsize;              /* logical file size */
    fsw_u64 finited;            /* initialized file size */
    fsw_u64 cvcn;               /* vcn of compress chunk: cbuf */
    fsw_u64 clcn[16];           /* cluster map of compress chunk */
    fsw_u8 *cbuf;               /* compress chunk/index block/symlink target */
};

static fsw_status_t fixup(fsw_u8 *record, char *magic, int sectorsize, int size)
{
    int off, cnt, i;
    fsw_u16 val;

    if(*(int *)record != *(int *)magic)
        return FSW_VOLUME_CORRUPTED;

    off = GETU16(record, 4);
    cnt = GETU16(record, 6);
    if(size && sectorsize*(cnt-1) != size)
        return FSW_VOLUME_CORRUPTED;
    val = GETU16(record, off);
    for(i=1; i<cnt; i++) {
        if(GETU16(record, i*sectorsize-2)!=val)
            return FSW_VOLUME_CORRUPTED;

        *(fsw_u16 *)(record+i*sectorsize-2) = *(fsw_u16 *)(record+off+i*2);
    }
    return FSW_SUCCESS;
}

/* only supported attribute name is $I30 */
static fsw_status_t find_attribute_direct(fsw_u8 *mft, int mftsize, int type, fsw_u8 **outptr, int *outlen)
{
    int namelen;
    fsw_u32 n;

    if(GETU32(mft, 0x18) < mftsize)
        mftsize = GETU32(mft, 0x18);
    mftsize -= GETU16(mft, 0x14);
    mft += GETU16(mft, 0x14);

    namelen = type>>ATTRBITS;
    type &= ATTRMASK;

    for(n = 0; mftsize >= 8; mft += n, mftsize -= n) {
        int t = GETU32(mft, 0);
        n = GETU32(mft, 4);
        if( t==0 || (t+1)==0 || t==0xffff || n<24 || mftsize<n)
            break;

        fsw_u8 ns = GETU8(mft, 9);
        fsw_u8 *nm = mft + GETU8(mft, 10);
        if(type==t && namelen==ns && (ns==0 || fsw_memeq(NAME_I30, nm, ns*2))) {
            if(outptr) *outptr = mft;
            if(outlen) *outlen = n;
            return FSW_SUCCESS;
        }
    }
    return FSW_NOT_FOUND;
}

/* only supported attribute name is $I30 */
static fsw_status_t find_attrlist_direct(fsw_u8 *atlst, int atlen, int type, fsw_u64 vcn, fsw_u64 *out, int *pos)
{
    fsw_u64 mftno = BADMFT;
    int namelen;

    namelen = type>>ATTRBITS;
    type &= ATTRMASK;

    while( *pos + 0x18 <= atlen) {
        int off = *pos;
        fsw_u32 t = GETU32(atlst, off);
        fsw_u32 n = GETU16(atlst, off+4);

        *pos = off + n;
        if(t==0 || (t+1)==0 || t==0xffff || n < 0x18 || *pos > atlen)
            break;

        fsw_u8 ns = GETU8(atlst, off+6);
        fsw_u8 *nm = atlst + off + GETU8(atlst, off+7);
        if( type == t && namelen==ns && (ns==0 || fsw_memeq(NAME_I30, nm, ns*2))) {
            fsw_u64 avcn = GETU64(atlst, off+8);
            if(vcn < avcn) {
                if(mftno == BADMFT)
                    return FSW_NOT_FOUND;
                *out = mftno;
                return FSW_SUCCESS;
            }
            if(vcn == avcn) {
                *out = GETU64(atlst, off+0x10) & MFTMASK;
                return FSW_SUCCESS;
            }
            mftno = GETU64(atlst, off+0x10) & MFTMASK;
        }
    }
    return FSW_NOT_FOUND;
}

static fsw_status_t get_extent(fsw_u8 **rlep, int *rlenp, fsw_u64 *lcnp, fsw_u64 *lenp, fsw_u64 *pos)
{
    fsw_u8 *rle = *rlep;
    fsw_u8 *rle_end = rle + *rlenp;
    int f = *rle++;
    fsw_u64 m = 1;
    fsw_u64 c = 0;
    fsw_u64 v = 0;

    int n = f & 0xf;
    if(n==0) return FSW_NOT_FOUND;

    if(rle + n > rle_end) return FSW_VOLUME_CORRUPTED;

    while(--n >= 0) {
        c += m * (*rle++);
        m <<= 8;
    }

    n = f >> 4;
    if(n==0) {
        /* LCN 0 as sparse, due to we don't need $Boot */
        *lcnp = 0;
        *lenp = c;
    } else {
        if(rle + n > rle_end) return FSW_VOLUME_CORRUPTED;

        m = 1;
        while(--n >= 0) {
            v += m * (*rle++);
            m <<= 8;
        }

        *pos += v;
        if(v & (m>>1))
            *pos -= m;

        *lcnp = *pos;
        *lenp = c;
    }
    *rlenp -= rle - *rlep;
    *rlep = rle;
    return FSW_SUCCESS;
}

static inline int attribute_ondisk(fsw_u8 *ptr, int len)
{
    return GETU8(ptr, 8);
}

static inline int attribute_compressed(fsw_u8 *ptr, int len)
{
    return (GETU8(ptr, 12) & 0xFF) == 1;
}

static inline int attribute_compressed_future(fsw_u8 *ptr, int len)
{
    return (GETU8(ptr, 12) & 0xFF) > 1;
}

static inline int attribute_sparse(fsw_u8 *ptr, int len)
{
    return GETU8(ptr, 12) & 0x8000;
}

static inline int attribute_encrypted(fsw_u8 *ptr, int len)
{
    return GETU8(ptr, 12) & 0x4000;
}

static void attribute_get_embeded(fsw_u8 *ptr, int len, fsw_u8 **outp, int *outlenp)
{
    int off = GETU16(ptr, 0x14);
    int olen = GETU16(ptr, 0x10);
    if(olen + off > len)
        olen = len - off;
    *outp = ptr + off;
    *outlenp = olen;
}

static void attribute_get_rle(fsw_u8 *ptr, int len, fsw_u8 **outp, int *outlenp)
{
    int off = GETU16(ptr, 0x20);
    int olen = len - off;
    *outp = ptr + off;
    *outlenp = olen;
}

static inline int attribute_rle_offset(fsw_u8 *ptr, int len)
{
    return GETU16(ptr, 0x20);
}

static inline fsw_u64 attribute_size(fsw_u8 *ptr, int len)
{
    return GETU8(ptr, 8) ? GETU64(ptr, 0x30) : GETU16(ptr, 0x10);
}

static inline fsw_u64 attribute_inited_size(fsw_u8 *ptr, int len)
{
    return GETU8(ptr, 8) ? GETU64(ptr, 0x38) : GETU16(ptr, 0x10);
}

static inline int attribute_has_vcn(fsw_u8 *ptr, int len, fsw_u64 vcn) {
    if(GETU8(ptr, 8)==0)
        return 1;
    return vcn >= GETU64(ptr, 0x10) && vcn <= GETU64(ptr, 0x18);
}

static inline fsw_u64 attribute_first_vcn(fsw_u8 *ptr, int len)
{
    return GETU8(ptr, 8) ? GETU64(ptr, 0x10) : 0;
}

static inline fsw_u64 attribute_last_vcn(fsw_u8 *ptr, int len)
{
    return GETU8(ptr, 8) ? GETU64(ptr, 0x18) : 0;
}

static fsw_status_t read_attribute_direct(struct fsw_ntfs_volume *vol, fsw_u8 *ptr, int len, fsw_u8 **optrp, int *olenp)
{
    int olen;

    if(attribute_ondisk(ptr, len) == 0) {
        /* EMBEDED DATA */
        attribute_get_embeded(ptr, len, &ptr, &len);
        *olenp = len;
        if(optrp) {
            *optrp = AllocatePool(len);
            fsw_memcpy(*optrp, ptr, len);
        }
        return FSW_SUCCESS;
    }

    olen = attribute_size(ptr, len);
    *olenp = olen;
    if(!optrp)
        return FSW_SUCCESS;

    fsw_u8 *buf = AllocatePool(olen);
    fsw_memzero(buf, olen);
    *optrp = buf;

    attribute_get_rle(ptr, len, &ptr, &len);

    fsw_u64 pos = 0;
    int clustersize = 1<<vol->clbits;
    fsw_u64 lcn, cnt;

    while(len > 0 && get_extent(&ptr, &len, &lcn, &cnt, &pos)==FSW_SUCCESS) {
        if(lcn) {
            for(; cnt>0; lcn++, cnt--) {
                fsw_u8 *block;
                if (fsw_block_get(&vol->g, lcn, 0, (void **)&block) != FSW_SUCCESS)
                {
                    FreePool(*optrp);
                    *optrp = NULL;
                    *olenp = 0;
                    return FSW_VOLUME_CORRUPTED;
                }
                fsw_memcpy(buf, block, clustersize > olen ? olen : clustersize);
                fsw_block_release(&vol->g, lcn, block);

                buf += clustersize;
                olen -= clustersize;
            }
        } else {
            buf += cnt << vol->clbits;
            olen -= cnt << vol->clbits;
        }
    }
    return FSW_SUCCESS;
}

static void init_mft(struct fsw_ntfs_volume *vol, struct ntfs_mft *mft, fsw_u64 mftno)
{
    mft->mftno = mftno;
    mft->buf = AllocatePool(1<<vol->mftbits);
    mft->atlst = NULL;
    mft->atlen = 0;
}

static void free_mft(struct ntfs_mft *mft)
{
    if(mft->buf) FreePool(mft->buf);
    if(mft->atlst) FreePool(mft->atlst);
}

static fsw_status_t load_atlist(struct fsw_ntfs_volume *vol, struct ntfs_mft *mft)
{
    fsw_u8 *ptr;
    int len;
    fsw_status_t err = find_attribute_direct(mft->buf, 1<<vol->mftbits, AT_ATTRIBUTE_LIST, &ptr, &len);
    if(err != FSW_SUCCESS)
        return err;
    return read_attribute_direct(vol, ptr, len, &mft->atlst, &mft->atlen);
}

static fsw_status_t read_mft(struct fsw_ntfs_volume *vol, fsw_u8 *mft, fsw_u64 mftno)
{
    int l = 0;
    int r = vol->extmap.used - 1;
    int m;
    fsw_u64 vcn = (mftno << vol->mftbits) >> vol->clbits;
    struct extent_slot *e = vol->extmap.extent;

    while(l <= r) {
        m = (l+r)/2;
        if(vcn < e[m].vcn) {
            r = m - 1;
        } else if(vcn >= e[m].vcn + e[m].cnt) {
            l = m + 1;
        } else if(vol->mftbits <= vol->clbits) {
            fsw_u64 lcn = e[m].lcn + (vcn - e[m].vcn);
            int offset = (mftno << vol->mftbits) & ((1<<vol->clbits)-1);
            fsw_u8 *buffer;
            fsw_status_t err;

            if(e[m].lcn + 1 == 0)
                return FSW_VOLUME_CORRUPTED;

            if ((err = fsw_block_get(&vol->g, lcn, 0, (void **)&buffer)) != FSW_SUCCESS)
                return FSW_VOLUME_CORRUPTED;

            fsw_memcpy(mft, buffer+offset, 1<<vol->mftbits);
            fsw_block_release(&vol->g, lcn, buffer);
            return fixup(mft, "FILE", 1<<vol->sctbits, 1<<vol->mftbits);
        } else {
            fsw_u8 *p = mft;
            fsw_u64 lcn = e[m].lcn + (vcn - e[m].vcn);
            fsw_u64 ecnt = e[m].cnt - (vcn - e[m].vcn);
            int count = 1 << (vol->mftbits - vol->clbits);
            fsw_status_t err;

            if(e[m].lcn + 1 == 0)
                return FSW_VOLUME_CORRUPTED;
            while(count-- > 0) {
                fsw_u8 *buffer;
                if ((err = fsw_block_get(&vol->g, lcn, 0, (void **)&buffer)) != FSW_SUCCESS)
                    return FSW_VOLUME_CORRUPTED;
                fsw_memcpy(p, buffer, 1<<vol->clbits);
                fsw_block_release(&vol->g, lcn, buffer);

                p += 1<<vol->clbits;
                ecnt--;
                vcn++;
                if(count==0) break;
                if(ecnt > 0) {
                    lcn++;
                } else if(++m >= vol->extmap.used || e[m].vcn != vcn) {
                    return FSW_VOLUME_CORRUPTED;
                } else {
                    lcn = e[m].lcn;
                    ecnt = e[m].cnt;
                }
            }
            return fixup(mft, "FILE", 1<<vol->sctbits, 1<<vol->mftbits);
        }
    }
    return FSW_NOT_FOUND;
}

static void init_attr(struct fsw_ntfs_volume *vol, struct ntfs_attr *attr, int type)
{
    fsw_memzero(attr, sizeof(*attr));
    attr->type = type;
    attr->emftno = BADMFT;
}

static void free_attr(struct ntfs_attr *attr)
{
    if(attr->emft) FreePool(attr->emft);
}

static fsw_status_t find_attribute(struct fsw_ntfs_volume *vol, struct ntfs_mft *mft, struct ntfs_attr *attr, fsw_u64 vcn)
{
    fsw_u8 *buf = mft->buf;
    if(mft->atlst && mft->atlen) {
        fsw_status_t err;
        fsw_u64 mftno;
        int pos = 0;

        err = find_attrlist_direct(mft->atlst, mft->atlen, attr->type, vcn, &mftno, &pos);
        if(err != FSW_SUCCESS)
            return err;

        if(mftno == mft->mftno) {
            buf = mft->buf;
        } else if(mftno == attr->emftno && attr->emft) {
            buf = attr->emft;
        } else {
            attr->emftno = BADMFT;
            err = read_mft(vol, attr->emft, mftno);
            if(err != FSW_SUCCESS)
                return err;
            attr->emftno = mftno;
            buf = attr->emft;
        }
    }
    return find_attribute_direct(buf, 1<<vol->mftbits, attr->type, &attr->ptr, &attr->len);
}

static fsw_status_t read_small_attribute(struct fsw_ntfs_volume *vol, struct ntfs_mft *mft, int type, fsw_u8 **optrp, int *olenp)
{
    fsw_status_t err;
    struct ntfs_attr attr;

    init_attr(vol, &attr, type);
    err = find_attribute(vol, mft, &attr, 0);
    if(err == FSW_SUCCESS)
        err = read_attribute_direct(vol, attr.ptr, attr.len, optrp, olenp);
    free_attr(&attr);
    return err;
}

static void add_single_mft_map(struct fsw_ntfs_volume *vol, fsw_u8 *mft)
{
    fsw_u8 *ptr;
    int len;

    if(find_attribute_direct(mft, 1<<vol->mftbits, AT_DATA, &ptr, &len)!=FSW_SUCCESS)
        return;

    if(attribute_ondisk(ptr, len) == 0)
        return;

    fsw_u64 vcn = GETU64(ptr, 0x10);
    int off = GETU16(ptr, 0x20);
    ptr += off;
    len -= off;

    fsw_u64 pos = 0;
    fsw_u64 lcn, cnt;

    while(len > 0 && get_extent(&ptr, &len, &lcn, &cnt, &pos)==FSW_SUCCESS) {
        if(lcn) {
            int u = vol->extmap.used;
            if(u >= vol->extmap.total) {
                vol->extmap.total = vol->extmap.extent ? u*2 : 16;
                struct extent_slot *e = AllocatePool(vol->extmap.total * sizeof(struct extent_slot));
                if(vol->extmap.extent) {
                    fsw_memcpy(e, vol->extmap.extent, u*sizeof(struct extent_slot));
                    FreePool(vol->extmap.extent);
                }
                vol->extmap.extent = e;
            }
            vol->extmap.extent[u].vcn = vcn;
            vol->extmap.extent[u].lcn = lcn;
            vol->extmap.extent[u].cnt = cnt;
            vol->extmap.used++;
        }
        vcn += cnt;
    }
}

static void add_mft_map(struct fsw_ntfs_volume *vol, struct ntfs_mft *mft)
{
    load_atlist(vol, mft);
    add_single_mft_map(vol, mft->buf);
    if(mft->atlst == NULL) return;

    fsw_u64 mftno;
    int pos = 0;

    fsw_u8 *emft = AllocatePool(1<<vol->mftbits);
    while(find_attrlist_direct(mft->atlst, mft->atlen, AT_DATA, 0, &mftno, &pos) == FSW_SUCCESS) {
        if(mftno == 0) continue;
        if(read_mft(vol, emft, mftno)==FSW_SUCCESS)
            add_single_mft_map(vol, emft);
    }
    FreePool(emft);
}

static int tobits(fsw_u32 val)
{
    return 31 - __builtin_clz(val);
}

static fsw_status_t fsw_ntfs_volume_mount(struct fsw_volume *volg)
{
    struct fsw_ntfs_volume *vol = (struct fsw_ntfs_volume *)volg;
    fsw_status_t err;
    fsw_u8 *buffer;
    int sector_size;
    int cluster_size;
    signed char tmp;
    fsw_u64 mft_start[2];
    struct ntfs_mft mft0;

    fsw_memzero((char *)vol+sizeof(*volg), sizeof(*vol)-sizeof(*volg));
    fsw_set_blocksize(volg, 512, 512);
    if ((err = fsw_block_get(volg, 0, 0, (void **)&buffer)) != FSW_SUCCESS)
        return FSW_UNSUPPORTED;

    if (!fsw_memeq(buffer+3, "NTFS    ", 8))
        return FSW_UNSUPPORTED;

    sector_size = GETU16(buffer, 0xB);
    if(sector_size==0 || (sector_size & (sector_size-1)) || sector_size < 0x100 || sector_size > 0x1000)
        return FSW_UNSUPPORTED;

    vol->sctbits = tobits(sector_size);
    vol->totalbytes = GETU64(buffer, 0x28) << vol->sctbits;
    Print(L"NTFS size=%ld M\n", vol->totalbytes>>20);

    cluster_size = GETU8(buffer, 0xD) * sector_size;
    if(cluster_size==0 || (cluster_size & (cluster_size-1)) || cluster_size > 0x10000)
        return FSW_UNSUPPORTED;

    vol->clbits = tobits(cluster_size);

    tmp = GETU8(buffer, 0x40);
    if(tmp > 0)
        vol->mftbits = vol->clbits + tobits(tmp);
    else
        vol->mftbits = -tmp;

    if(vol->mftbits < vol->sctbits || vol->mftbits > 16)
        return FSW_UNSUPPORTED;

    tmp = GETU8(buffer, 0x44);
    if(tmp > 0)
        vol->idxbits = vol->clbits + tobits(tmp);
    else
        vol->idxbits = -tmp;

    if(vol->idxbits < vol->sctbits || vol->idxbits > 16)
        return FSW_UNSUPPORTED;

    mft_start[0] = GETU64(buffer, 0x30);
    mft_start[1] = GETU64(buffer, 0x38);

    fsw_block_release(volg, 0, (void *)buffer);
    fsw_set_blocksize(volg, cluster_size, cluster_size);

    init_mft(vol, &mft0, MFTNO_MFT);
    for(tmp=0; tmp<2; tmp++) {
        fsw_u8 *ptr = mft0.buf;
        int len = 1 << vol->mftbits;
        fsw_u64 lcn = mft_start[tmp];
        while(len > 0) {
            if ((err = fsw_block_get(volg, lcn, 0, (void **)&buffer)) != FSW_SUCCESS)
            {
                free_mft(&mft0);
                return FSW_UNSUPPORTED;
            }
            int n = vol->mftbits < vol->clbits ? (1<<vol->mftbits) : cluster_size;
            fsw_memcpy(ptr, buffer, n);
            fsw_block_release(volg, lcn, (void *)buffer);
            ptr += n;
            len -= n;
            lcn++;
        }
        err = fixup(mft0.buf, "FILE", sector_size, 1<<vol->mftbits);
        if(err != FSW_SUCCESS)
            return err;
    }

    add_mft_map(vol, &mft0);

    {
    int i;
    for(i=0; i<vol->extmap.used; i++)
        Print(L"extent %d: vcn=%lx lcn=%lx len=%lx\n",
                i,
                vol->extmap.extent[i].vcn,
                vol->extmap.extent[i].lcn,
                vol->extmap.extent[i].cnt);
    }

    free_mft(&mft0);

    /* load $Volume name */
    init_mft(vol, &mft0, MFTNO_VOLUME);
    fsw_u8 *ptr;
    int len;
    if(read_mft(vol, mft0.buf, MFTNO_VOLUME)==FSW_SUCCESS &&
            find_attribute_direct(mft0.buf, 1<<vol->mftbits, AT_VOLUME_NAME, &ptr, &len)==FSW_SUCCESS &&
            GETU8(ptr, 8)==0)
    {
        struct fsw_string s;
        s.type = FSW_STRING_TYPE_UTF16_LE;
        s.size = GETU16(ptr, 0x10);
        s.len = s.size / 2;
        s.data = ptr + GETU16(ptr, 0x14);
        Print(L"Volume name [%.*ls]\n", s.len, s.data);
        err = fsw_strdup_coerce(&volg->label, volg->host_string_type, &s);
    }
    free_mft(&mft0);

    err = fsw_dnode_create_root(volg, MFTNO_ROOT, &volg->root);
    if (err)
        return err;

    return FSW_SUCCESS;
}

static void fsw_ntfs_volume_free(struct fsw_volume *volg)
{
    struct fsw_ntfs_volume *vol = (struct fsw_ntfs_volume *)volg;
    if(vol->extmap.extent)
        FreePool(vol->extmap.extent);
    if(vol->upcase && vol->upcase != upcase)
        FreePool((void *)vol->upcase);
}

static fsw_status_t fsw_ntfs_volume_stat(struct fsw_volume *volg, struct fsw_volume_stat *sb)
{
    struct fsw_ntfs_volume *vol = (struct fsw_ntfs_volume *)volg;
    sb->total_bytes = vol->totalbytes;
    /* reading through cluster bitmap is too costly */
    sb->free_bytes  = 0;
    return FSW_SUCCESS;
}

static fsw_status_t fsw_ntfs_dnode_fill(struct fsw_volume *volg, struct fsw_dnode *dnog)
{
    struct fsw_ntfs_volume *vol = (struct fsw_ntfs_volume *)volg;
    struct fsw_ntfs_dnode *dno = (struct fsw_ntfs_dnode *)dnog;
    fsw_status_t err;
    int len;

    fsw_memzero((char *)dno+sizeof(*dnog), sizeof(*dno)-sizeof(*dnog));
    init_mft(vol, &dno->mft, dno->g.dnode_id);
    err = read_mft(vol, dno->mft.buf, dno->g.dnode_id);
    if(err != FSW_SUCCESS)
        return err;

    len = GETU8(dno->mft.buf, 22);
    if( (len & 1) == 0 )
        return FSW_NOT_FOUND;

    load_atlist(vol, &dno->mft);

    if(read_small_attribute(vol, &dno->mft, AT_REPARSE_POINT, &dno->cbuf, &len)==FSW_SUCCESS) {
        switch(GETU32(dno->cbuf, 0)) {
            case 0xa0000003:
            case 0xa000000c:
                dno->g.size = len;
                dno->g.type = FSW_DNODE_TYPE_SYMLINK;
                dno->islink = 1;
                dno->fsize = len;
                return FSW_SUCCESS;
            default:
                FreePool(dno->cbuf);
                dno->cbuf = NULL;
        };
    }

    if( (len & 2) ) {
        dno->g.type = FSW_DNODE_TYPE_DIR;
        /* $INDEX_ROOT:$I30 must present */
        err = read_small_attribute(vol, &dno->mft, AT_INDEX_ROOT|AT_I30, &dno->idxroot, &dno->rootsz);
        if(err != FSW_SUCCESS)
        {
            Print(L"dno_fill INDEX_ROOT:$I30 error %d\n", err);
            return err;
        }

        dno->idxsz = GETU32(dno->idxroot, 8);
        if(dno->idxsz == 0)
            dno->idxsz = 1<<vol->idxbits;

        /* $Bitmap:$I30 is optional */
        err = read_small_attribute(vol, &dno->mft, AT_BITMAP|AT_I30, &dno->idxbmp, &dno->bmpsz);
        if(err != FSW_SUCCESS && err != FSW_NOT_FOUND)
        {
            Print(L"dno_fill $Bitmap:$I30 error %d\n", err);
            return err;
        }

        /* $INDEX_ALLOCATION:$I30 is optional */
        init_attr(vol, &dno->attr, AT_INDEX_ALLOCATION|AT_I30);
        err = find_attribute(vol, &dno->mft, &dno->attr, 0);
        if(err == FSW_SUCCESS) {
            dno->has_idxtree = 1;
            dno->fsize = attribute_size(dno->attr.ptr, dno->attr.len);
            dno->finited = dno->fsize;
        } else if(err != FSW_NOT_FOUND) {
            Print(L"dno_fill $INDEX_ALLOCATION:$I30 error %d\n", err);
            return err;
        }

    } else {
        dno->g.type = FSW_DNODE_TYPE_FILE;
        init_attr(vol, &dno->attr, AT_DATA);
        err = find_attribute(vol, &dno->mft, &dno->attr, 0);
        if(err != FSW_SUCCESS)
        {
            Print(L"dno_fill AT_DATA error %d\n", err);
            return err;
        }
        dno->embeded = !attribute_ondisk(dno->attr.ptr, dno->attr.len);
        dno->fsize = attribute_size(dno->attr.ptr, dno->attr.len);
        dno->finited = attribute_inited_size(dno->attr.ptr, dno->attr.len);
        if(attribute_encrypted(dno->attr.ptr, dno->attr.len))
            dno->unreadable = 1;
        else if(attribute_compressed_future(dno->attr.ptr, dno->attr.len))
            dno->unreadable = 1;
        else if(attribute_compressed(dno->attr.ptr, dno->attr.len))
            dno->compressed = 1;
        dno->cvcn = BADVCN;
        dno->g.size = dno->fsize;
    }
    return FSW_SUCCESS;
}

static void fsw_ntfs_dnode_free(struct fsw_volume *vol, struct fsw_dnode *dnog)
{
    struct fsw_ntfs_dnode *dno = (struct fsw_ntfs_dnode *)dnog;
    free_mft(&dno->mft);
    free_attr(&dno->attr);
    if(dno->idxroot)
        FreePool(dno->idxroot);
    if(dno->idxbmp)
        FreePool(dno->idxbmp);
    if(dno->cbuf)
        FreePool(dno->cbuf);
}

static fsw_u32 get_ntfs_time(fsw_u8 *buf, int pos)
{
    fsw_u64 t = GETU64(buf, pos);
    t = FSW_U64_DIV(t, 10000000);
    t -= 134774ULL * 86400;
    return t;
}

static fsw_status_t fsw_ntfs_dnode_stat(struct fsw_volume *volg, struct fsw_dnode *dnog, struct fsw_dnode_stat *sb)
{
    struct fsw_ntfs_volume *vol = (struct fsw_ntfs_volume *)volg;
    struct fsw_ntfs_dnode *dno = (struct fsw_ntfs_dnode *)dnog;
    fsw_status_t err;
    fsw_u16 attr;
    fsw_u8 *ptr;
    int len;

    err = find_attribute_direct(dno->mft.buf, 1<<vol->mftbits, AT_STANDARD_INFORMATION, &ptr, &len);

    if(err != FSW_SUCCESS || GETU8(ptr, 8))
        return err;

    ptr += GETU16(ptr, 0x14);
    attr = GETU8(ptr, 0x20); /* only lower 8 of 32 bit is used */
    attr &= EFI_FILE_READ_ONLY | EFI_FILE_HIDDEN | EFI_FILE_SYSTEM | EFI_FILE_ARCHIVE;
    /* add DIR again if symlink */
    if(GETU8(dno->mft.buf, 22) & 2)
        attr |= EFI_FILE_DIRECTORY;

    fsw_store_attr_efi(sb, attr);
    sb->used_bytes = dno->fsize;
    fsw_store_time_posix(sb, FSW_DNODE_STAT_ATIME, get_ntfs_time(ptr, 24));
    fsw_store_time_posix(sb, FSW_DNODE_STAT_CTIME, get_ntfs_time(ptr, 8));
    fsw_store_time_posix(sb, FSW_DNODE_STAT_MTIME, get_ntfs_time(ptr, 16));

    return FSW_SUCCESS;
}

static fsw_status_t fsw_ntfs_dnode_get_lcn(struct fsw_ntfs_volume *vol, struct fsw_ntfs_dnode *dno, fsw_u64 vcn, fsw_u64 *lcnp)
{
    fsw_status_t err;
    if(vcn >= dno->cext.vcn && vcn < dno->cext.vcn+dno->cext.cnt) {
        *lcnp = dno->cext.lcn + vcn - dno->cext.vcn;
        return FSW_SUCCESS;
    }
    if(!attribute_has_vcn(dno->attr.ptr, dno->attr.len, vcn)) {
        err = find_attribute(vol, &dno->mft, &dno->attr, vcn);
        if( err != FSW_SUCCESS )
            return err;
        if(!attribute_has_vcn(dno->attr.ptr, dno->attr.len, vcn))
            return FSW_VOLUME_CORRUPTED;
    }
    fsw_u8 *ptr = dno->attr.ptr;
    int len = dno->attr.len;
    fsw_u64 pos = 0;
    fsw_u64 lcn, cnt;
    fsw_u64 svcn = attribute_first_vcn(ptr, len);
    fsw_u64 evcn = attribute_last_vcn(ptr, len) + 1;
    int off = GETU16(ptr, 0x20);
    ptr += off;
    len -= off;
    while(len > 0 && get_extent(&ptr, &len, &lcn, &cnt, &pos)==FSW_SUCCESS) {
        if(vcn >= svcn && vcn < svcn+cnt) {
            dno->cext.vcn = svcn;
            dno->cext.lcn = lcn;
            dno->cext.cnt = cnt;
            if(lcn == 0)
                return FSW_NOT_FOUND;
            *lcnp = lcn + vcn - svcn;
            return FSW_SUCCESS;
        }
        svcn += cnt;
        if(svcn >= evcn)
            break;
    }
    return FSW_NOT_FOUND;
}

static int fsw_ntfs_read_buffer(struct fsw_ntfs_volume *vol, struct fsw_ntfs_dnode *dno, fsw_u8 *buf, fsw_u64 offset, int size)
{
    if(dno->embeded) {
        fsw_u8 *ptr;
        int len;
        attribute_get_embeded(dno->attr.ptr, dno->attr.len, &ptr, &len);
        if(size > len)
            size = len;
        fsw_memcpy(buf, ptr, size);
        return size;
    }

    if(!dno->attr.ptr || !dno->attr.len) {
        Print(L"BAD--------: attr.ptr %p attr.len %x cleared\n", dno->attr.ptr, dno->attr.len);
        if(find_attribute(vol, &dno->mft, &dno->attr, 0) != FSW_SUCCESS)
            return 0;
    }

    if(offset >= dno->fsize)
        return 0;
    if(offset + size >= dno->fsize)
        size = dno->fsize - offset;

    if(offset >= dno->finited) {
        fsw_memzero(buf, size);
        return size;
    }

    int ret = 0;
    int zsize = 0;
    if(offset + size >= dno->finited) {
        zsize = offset + size - dno->finited;
        size = dno->finited - offset;
    }

    fsw_u64 vcn = offset >> vol->clbits;
    int boff = offset & ((1<<vol->clbits)-1);
    fsw_u64 lcn = 0;

    while(size > 0) {
        fsw_u8 *block;
        fsw_status_t err;
        int bsz;

        err = fsw_ntfs_dnode_get_lcn(vol, dno, vcn, &lcn);
        if (err != FSW_SUCCESS) break;

        err = fsw_block_get(&vol->g, lcn, 0, (void **)&block);
        if (err != FSW_SUCCESS) break;

        bsz = (1<<vol->clbits) - boff;
        if(bsz > size)
            bsz = size;

        fsw_memcpy(buf, block+boff, bsz);
        fsw_block_release(&vol->g, lcn, block);

        ret += bsz;
        buf += bsz;
        size -= bsz;
        boff = 0;
    }
    if(size==0 && zsize > 0) {
        fsw_memzero(buf, zsize);
        ret += zsize;
    }
    return ret;
}

static fsw_status_t fsw_ntfs_get_extent_embeded(struct fsw_ntfs_volume *vol, struct fsw_ntfs_dnode *dno, struct fsw_extent *extent)
{
    if(extent->log_start > 0)
        return FSW_NOT_FOUND;
    extent->log_count = 1;
    extent->buffer = AllocatePool(1<<vol->clbits);
    fsw_u8 *ptr;
    int len;
    attribute_get_embeded(dno->attr.ptr, dno->attr.len, &ptr, &len);
    if(len > (1<<vol->clbits))
        len = 1<<vol->clbits;
    fsw_memcpy(extent->buffer, ptr, len);
    extent->type = FSW_EXTENT_TYPE_BUFFER;
    return FSW_SUCCESS;
}

static int ntfs_decomp_1page(fsw_u8 *src, int slen, fsw_u8 *dst) {
    int soff = 0;
    int doff = 0;
    while(soff < slen) {
        int j;
        int tag = src[soff++];
        for(j = 0; j < 8 && soff < slen; j++) {
            if(tag & (1<<j)){
                int len;
                int back;
                int bits;

                if(!doff || soff + 2 > slen)
                    return -1;
                len = GETU16(src, soff); soff += 2;
                bits = __builtin_clz((doff-1)>>3)-19;
                back = (len >> bits) + 1;
                len = (len & ((1<<bits)-1)) + 3;
                if(doff < back || doff + len > 0x1000)
                    return -1;
                while(len-- > 0) {
                    dst[doff] = dst[doff-back];
                    doff++;
                }
            } else {
                if(doff >= 0x1000)
                    return -1;
                dst[doff++] = src[soff++];
            }
        }
    }
    return doff;
}

static int ntfs_decomp(fsw_u8 *src, int slen, fsw_u8 *dst, int npage) {
    fsw_u8 *se = src + slen;
    fsw_u8 *de = dst + (npage<<12);
    int i;
    for(i=0; i<npage; i++) {
        fsw_u16 slen = GETU16(src, 0);
        int comp = slen & 0x8000;
        slen = (slen&0xfff)+1;
        src += 2;

        if(src + slen > se || dst + 0x1000 > de)
            return -1;

        if(!comp) {
            fsw_memcpy(dst, src, slen);
            if(slen < 0x1000)
                fsw_memzero(dst+slen, 0x1000-slen);
        } else if(slen == 1) {
            fsw_memzero(dst, 0x1000);
        } else {
            int dlen = ntfs_decomp_1page(src, slen, dst);
            if(dlen < 0)
                return -1;
            if(dlen < 0x1000)
                fsw_memzero(dst+dlen, 0x1000-dlen);
        }
        src += slen;
        dst += 0x1000;
    }
    return 0;
}

static fsw_status_t fsw_ntfs_get_extent_compressed(struct fsw_ntfs_volume *vol, struct fsw_ntfs_dnode *dno, struct fsw_extent *extent)
{
    if(vol->clbits > 16)
        return FSW_VOLUME_CORRUPTED;

    if((extent->log_start << vol->clbits) > dno->fsize)
        return FSW_NOT_FOUND;

    int i;
    fsw_u64 vcn = extent->log_start & ~15;

    if(vcn == dno->cvcn)
        goto hit;
    dno->cvcn = vcn;
    dno->cperror = 0;
    dno->cpfull = 0;
    dno->cpzero = 0;

    for(i=0; i<16; i++) {
        fsw_status_t err;
        err = fsw_ntfs_dnode_get_lcn(vol, dno, vcn+i, &dno->clcn[i]);
        if(err == FSW_NOT_FOUND) {
            break;
        } else if(err != FSW_SUCCESS) {
            Print(L"BAD LCN\n");
            dno->cperror = 1;
            return FSW_VOLUME_CORRUPTED;
        }
    }
    if(i == 0)
        dno->cpzero = 1;
    else if(i==16)
        dno->cpfull = 1;
    else {
        if(dno->cbuf == NULL)
            dno->cbuf = AllocatePool(16<<vol->clbits);
        fsw_u8 *src = AllocatePool(i << vol->clbits);
        int b;
        for(b=0; b<i; b++) {
            char *block;
            if (fsw_block_get(&vol->g, dno->clcn[b], 0, (void **)&block) != FSW_SUCCESS) {
                dno->cperror = 1;
                Print(L"Read ERROR at block %d\n", i);
                break;
            }
            fsw_memcpy(src+(b<<vol->clbits), block, 1<<vol->clbits);
            fsw_block_release(&vol->g, dno->clcn[b], block);
        }

        if(dno->fsize >= ((vcn+16)<<vol->clbits))
            b = 16<<vol->clbits>>12;
        else
            b = (dno->fsize - (vcn << vol->clbits) + 0xfff)>>12;
        if(!dno->cperror && ntfs_decomp(src, i<<vol->clbits, dno->cbuf, b) < 0)
            dno->cperror = 1;
        FreePool(src);
    }
hit:
    if(dno->cperror)
        return FSW_VOLUME_CORRUPTED;
    i = extent->log_start - vcn;
    if(dno->cpfull) {
        fsw_u64 lcn = dno->clcn[i];
        extent->phys_start = lcn;
        extent->log_count = 1;
        extent->type = FSW_EXTENT_TYPE_PHYSBLOCK;
        for(i++, lcn++; i<16 && lcn==dno->clcn[i]; i++, lcn++)
                extent->log_count++;
    } else if(dno->cpzero) {
        extent->log_count = 16 - i;
        extent->buffer = NULL;
        extent->type = FSW_EXTENT_TYPE_SPARSE;
    } else {
        extent->log_count = 1;
        extent->buffer = AllocatePool(1<<vol->clbits);
        fsw_memcpy(extent->buffer, dno->cbuf + (i<<vol->clbits), 1<<vol->clbits);
        extent->type = FSW_EXTENT_TYPE_BUFFER;
    }
    return FSW_SUCCESS;
}

static fsw_status_t fsw_ntfs_get_extent_sparse(struct fsw_ntfs_volume *vol, struct fsw_ntfs_dnode *dno, struct fsw_extent *extent)
{
    fsw_status_t err;

    if((extent->log_start << vol->clbits) > dno->fsize)
        return FSW_NOT_FOUND;
    if((extent->log_start << vol->clbits) > dno->finited)
    {
        extent->log_count = 1;
        extent->buffer = NULL;
        extent->type = FSW_EXTENT_TYPE_SPARSE;
        return FSW_SUCCESS;
    }
    fsw_u64 lcn;
    err = fsw_ntfs_dnode_get_lcn(vol, dno, extent->log_start, &lcn);
    if(err == FSW_NOT_FOUND) {
        extent->log_count = 1;
        extent->buffer = NULL;
        extent->type = FSW_EXTENT_TYPE_SPARSE;
        return FSW_SUCCESS;
    }
    if(err != FSW_SUCCESS)
        return err;
    extent->phys_start = lcn;
    extent->log_count = 1;
    if(extent->log_start >= dno->cext.vcn && extent->log_start < dno->cext.vcn+dno->cext.cnt)
        extent->log_count = dno->cext.cnt + extent->log_start - dno->cext.vcn;
    extent->type = FSW_EXTENT_TYPE_PHYSBLOCK;
    return FSW_SUCCESS;
}

static fsw_status_t fsw_ntfs_get_extent(struct fsw_volume *volg, struct fsw_dnode *dnog, struct fsw_extent *extent)
{
    struct fsw_ntfs_volume *vol = (struct fsw_ntfs_volume *)volg;
    struct fsw_ntfs_dnode *dno = (struct fsw_ntfs_dnode *)dnog;

    if(dno->unreadable)
        return FSW_UNSUPPORTED;
    if(dno->embeded)
        return fsw_ntfs_get_extent_embeded(vol, dno, extent);
    if(dno->compressed)
        return fsw_ntfs_get_extent_compressed(vol, dno, extent);
    return fsw_ntfs_get_extent_sparse(vol, dno, extent);
}

static fsw_status_t load_upcase(struct fsw_ntfs_volume *vol)
{
    fsw_status_t err;
    struct ntfs_mft mft;
    init_mft(vol, &mft, MFTNO_UPCASE);
    err = read_mft(vol, mft.buf, MFTNO_UPCASE);
    if(err == FSW_SUCCESS) {
        if((err = read_small_attribute(vol, &mft, AT_DATA, (fsw_u8 **)&vol->upcase, &vol->upcount))==FSW_SUCCESS) {
            vol->upcount /= 2;
#ifndef FSW_LITTLE_ENDIAN
            int i;
            for( i=0; i<vol->upcount; i++)
                vol->upcase[i] = fsw_u16_le_swap(vol->upcase[i]);
#endif
        }
    }
    free_mft(&mft);
    return err;
}

static int ntfs_filename_cmp(struct fsw_ntfs_volume *vol, fsw_u8 *p1, int s1, fsw_u8 *p2, int s2)
{
    while(s1 > 0 && s2 > 0) {
        fsw_u16 c1 = GETU16(p1,0);
        fsw_u16 c2 = GETU16(p2,0);
        if(c1 < 0x80 || c2 < 0x80) {
            if(c1 < 0x80) c1 = upcase[c1];
            if(c2 < 0x80) c2 = upcase[c2];
        } else {
            /*
             * Only load upcase table if both char is international.
             * We assume international char never upcased to ASCII.
             */
            if(!vol->upcase) {
                load_upcase(vol);
                if(!vol->upcase) {
                    /* use raw value & prevent load again */
                    vol->upcase = upcase;
                    vol->upcount = 0;
                }
            }
            if(c1 < vol->upcount) c1 = vol->upcase[c1];
            if(c2 < vol->upcount) c2 = vol->upcase[c2];
        }
        if(c1 < c2)
            return -1;
        if(c1 > c2)
            return 1;
        p1+=2;
        p2+=2;
        s1--;
        s2--;
    }
    if(s1 < s2)
        return -1;
    if(s1 > s2)
        return 1;
    return 0;
}

static fsw_status_t fsw_ntfs_create_subnode(struct fsw_ntfs_dnode *dno, fsw_u8 *buf, struct fsw_dnode **child_dno)
{
    fsw_u64 mftno = GETU64(buf, 0) & MFTMASK;
    if(mftno < MFTNO_META)
        return FSW_NOT_FOUND;

    int type = GETU32(buf, 0x48) & 0x10000000 ? FSW_DNODE_TYPE_DIR: FSW_DNODE_TYPE_FILE;
    struct fsw_string s;
    s.type = FSW_STRING_TYPE_UTF16_LE;
    s.len = GETU8(buf, 0x50);
    s.size = s.len * 2;
    s.data = buf + 0x52;

    return fsw_dnode_create(&dno->g, mftno, type, &s, child_dno);
}

static fsw_u8 *fsw_ntfs_read_index_block(struct fsw_ntfs_volume *vol, struct fsw_ntfs_dnode *dno, fsw_u64 block)
{
    if(dno->cbuf==NULL)
        dno->cbuf = AllocatePool(dno->idxsz);
    else if(block == dno->cvcn)
        return dno->cbuf;

    dno->cvcn = 0;
    if(fsw_ntfs_read_buffer(vol, dno, dno->cbuf, (block-1)*dno->idxsz, dno->idxsz) != dno->idxsz)
        return NULL;
    if(fixup(dno->cbuf, "INDX", 1<<vol->sctbits, dno->idxsz) != FSW_SUCCESS)
        return NULL;

    dno->cvcn = block;
    return dno->cbuf;
}

static fsw_status_t fsw_ntfs_dir_lookup(struct fsw_volume *volg, struct fsw_dnode *dnog, struct fsw_string *lookup_name, struct fsw_dnode **child_dno)
{
    struct fsw_ntfs_volume *vol = (struct fsw_ntfs_volume *)volg;
    struct fsw_ntfs_dnode *dno = (struct fsw_ntfs_dnode *)dnog;
    int depth = 0;
    struct fsw_string s;
    fsw_u8 *buf;
    int len;
    int off;
    fsw_status_t err;
    fsw_u64 block;

    *child_dno = NULL;
    err = fsw_strdup_coerce(&s, FSW_STRING_TYPE_UTF16_LE, lookup_name);
    if(err)
        return err;

    /* start from AT_INDEX_ROOT */
    buf = dno->idxroot + 16;
    len = dno->rootsz - 16;
    if(len < 0x18)
        goto notfound;

    while(depth < 10) {
        /* real index size */
        if(GETU32(buf, 4) < len)
            len = GETU32(buf, 4);

        /* skip index header */
        off = GETU32(buf, 0);
        if(off >= len)
            goto notfound;

        block = 0;
        while(off + 0x18 <= len) {
            int flag = GETU8(buf, off+12);
            int next = off + GETU16(buf, off+8);
            int cmp;

            if(flag & 2) {
                /* the end of index entry */
                cmp = -1;
                Print(L"depth %d len %x off %x flag %x next %x cmp %d\n", depth, len, off, flag, next, cmp);
            } else {
                int nlen = GETU8(buf, off+0x50);
                fsw_u8 *name = buf+off+0x52;
                cmp = ntfs_filename_cmp(vol, s.data, s.len, name, nlen);
                Print(L"depth %d len %x off %x flag %x next %x cmp %d name %d[%.*ls]\n", depth, len, off, flag, next, cmp, nlen, nlen, name);
            }

            if(cmp == 0) {
                fsw_strfree(&s);
                return fsw_ntfs_create_subnode(dno, buf+off, child_dno);
            } else if(cmp < 0) {
                if(!(flag & 1) || !dno->has_idxtree)
                    goto notfound;
                block = GETU64(buf, next-8) + 1;
                break;
            } else { /* cmp > 0 */
                off = next;
            }
        }
        if(!block)
            break;

        if(!(buf = fsw_ntfs_read_index_block(vol, dno, block)))
            break;
        buf += 24;
        len = dno->idxsz - 24;
        depth++;
    }

notfound:
    fsw_strfree(&s);
    return FSW_NOT_FOUND;
}

static inline void set_shand_pos( struct fsw_shandle *shand, int block, int off)
{
    shand->pos = (((fsw_u64)block) << 32) + off;
}

static inline int test_idxbmp(struct fsw_ntfs_dnode *dno, int block)
{
    int mask;
    if(dno->idxbmp==NULL)
        return 1;
    block--;
    mask = 1 << (block & 7);
    block >>= 3;
    if(block > dno->bmpsz)
        return 0;
    return dno->idxbmp[block] & mask;
}

#define shand_pos(x,y)  (((fsw_u64)(x)<<32)|(y))
static fsw_status_t fsw_ntfs_dir_read(struct fsw_volume *volg, struct fsw_dnode *dnog, struct fsw_shandle *shand, struct fsw_dnode **child_dno)
{
    struct fsw_ntfs_volume *vol = (struct fsw_ntfs_volume *)volg;
    struct fsw_ntfs_dnode *dno = (struct fsw_ntfs_dnode *)dnog;
    /*
     * high 32 bit: index block#
     *          0 --> index root
     *          >0 --> vcn+1
     * low 32 bit: index offset
     */
    int off = shand->pos & 0xFFFFFFFF;
    int block = shand->pos >> 32;
    int mblocks;

    mblocks = FSW_U64_DIV(dno->fsize, dno->idxsz);

    while(block <= mblocks) {
        fsw_u8 *buf;
        int len;
        if(block == 0) {
            /* AT_INDEX_ROOT */
            buf = dno->idxroot + 16;
            len = dno->rootsz - 16;
            if(len < 0x18)
                goto miss;
        } else if(!test_idxbmp(dno, block) || !(buf = fsw_ntfs_read_index_block(vol, dno, block)))
        {
            /* unused or bad index block */
            goto miss;
        } else {
            /* AT_INDEX_ALLOCATION block */
            buf += 24;
            len = dno->idxsz - 24;
        }
        if(GETU32(buf, 4) < len)
            len = GETU32(buf, 4);
        if(off == 0)
            off = GETU32(buf, 0);
        Print(L"block %d len %x off %x\n", block, len, off);
        while(off + 0x18 <= len) {
            int flag = GETU8(buf, off+12);
            if(flag & 2) break;
            int next = off + GETU16(buf, off+8);
            Print(L"flag %x next %x nt %x [%.*ls]\n", flag, next, GETU8(buf, off+0x51), GETU8(buf, off+0x50), buf+off+0x52);
            if((GETU8(buf, off+0x51) != 2)) {
                /* LONG FILE NAME */
                fsw_status_t err = fsw_ntfs_create_subnode(dno, buf+off, child_dno);
                if(err != FSW_NOT_FOUND) {
                    set_shand_pos(shand, block, next);
                    return err;
                }
                // skip internal MFT record
            }
            off = next;
        }
miss:
        if(!dno->has_idxtree)
            break;
        block++;
        off = 0;
    }
    set_shand_pos(shand, mblocks+1, 0);
    return FSW_NOT_FOUND;
}

static fsw_status_t fsw_ntfs_readlink(struct fsw_volume *volg, struct fsw_dnode *dnog, struct fsw_string *link)
{
    struct fsw_ntfs_dnode *dno = (struct fsw_ntfs_dnode *)dnog;
    fsw_u8 *name;
    int i;
    int len;

    if(!dno->islink)
        return FSW_UNSUPPORTED;

    name = dno->cbuf + 0x10 + GETU16(dno->cbuf, 8);
    len = GETU16(dno->cbuf, 10);
    if(GETU32(dno->cbuf, 0) == 0xa000000c)
        name += 4;

    for(i=0; i<len; i+=2)
        if(GETU16(name, i)=='\\')
            *(fsw_u16 *)(name+i) = fsw_u16_le_swap('/');

    if(len > 6 && GETU16(name,0)=='/' && GETU16(name,2)=='?' &&
            GETU16(name,4)=='?' && GETU16(name,6)=='/' &&
            GETU16(name,10)==':' && GETU16(name,12)=='/' &&
            (GETU16(name,8)|0x20)>='a' && (GETU16(name,8)|0x20)<='z')
    {
        len -= 12;
        name += 12;
    }
    struct fsw_string s;
    s.type = FSW_STRING_TYPE_UTF16_LE;
    s.size = len;
    s.len = len/2;
    s.data = name;
    return fsw_strdup_coerce(link, volg->host_string_type, &s);
}

//
// Dispatch Table
//

struct fsw_fstype_table   FSW_FSTYPE_TABLE_NAME(ntfs) = {
    { FSW_STRING_TYPE_UTF8, 4, 4, "ntfs" },
    sizeof(struct fsw_ntfs_volume),
    sizeof(struct fsw_ntfs_dnode),

    fsw_ntfs_volume_mount,
    fsw_ntfs_volume_free,
    fsw_ntfs_volume_stat,
    fsw_ntfs_dnode_fill,
    fsw_ntfs_dnode_free,
    fsw_ntfs_dnode_stat,
    fsw_ntfs_get_extent,
    fsw_ntfs_dir_lookup,
    fsw_ntfs_dir_read,
    fsw_ntfs_readlink,
};

// EOF