/*      $NetBSD: ntfs_compr.c,v 1.6 2015/02/20 17:08:13 maxv Exp $      */

/*-
* Copyright (c) 1998, 1999 Semen Ustimenko
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
*    notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
*    notice, this list of conditions and the following disclaimer in the
*    documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
*      Id: ntfs_compr.c,v 1.4 1999/05/12 09:42:54 semenu Exp
*/

#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: ntfs_compr.c,v 1.6 2015/02/20 17:08:13 maxv Exp $");

#include <sys/param.h>
#include <sys/systm.h>
#include <sys/namei.h>
#include <sys/kernel.h>
#include <sys/vnode.h>
#include <sys/mount.h>
#include <sys/malloc.h>

#include <fs/ntfs/ntfs.h>
#include <fs/ntfs/ntfs_compr.h>

#define GET_UINT16(addr)        (*((u_int16_t *)(addr)))

int
ntfs_uncompblock(u_int8_t *dbuf, u_int8_t *cbuf)
{
       u_int32_t ctag;
       int len, dshift, lmask;
       int blen, boff;
       int i, j;
       int pos, cpos;

       len = GET_UINT16(cbuf) & 0xFFF;
       dprintf(("ntfs_uncompblock: block length: %d + 3, 0x%x,0x%04x\n",
           len, len, GET_UINT16(cbuf)));

       if (!(GET_UINT16(cbuf) & 0x8000)) {
               if ((len + 1) != NTFS_COMPBLOCK_SIZE) {
                       dprintf(("ntfs_uncompblock: len: %x instead of %d\n",
                           len, 0xfff));
               }
               memcpy(dbuf, cbuf + 2, len + 1);
               memset(dbuf + len + 1, 0, NTFS_COMPBLOCK_SIZE - 1 - len);
               return len + 3;
       }
       cpos = 2;
       pos = 0;
       while ((cpos < len + 3) && (pos < NTFS_COMPBLOCK_SIZE)) {
               ctag = cbuf[cpos++];
               for (i = 0; (i < 8) && (pos < NTFS_COMPBLOCK_SIZE); i++) {
                       if (ctag & 1) {
                               for (j = pos - 1, lmask = 0xFFF, dshift = 12;
                                    j >= 0x10; j >>= 1) {
                                       dshift--;
                                       lmask >>= 1;
                               }
                               boff = -1 - (GET_UINT16(cbuf + cpos) >> dshift);
                               blen = 3 + (GET_UINT16(cbuf + cpos) & lmask);
                               for (j = 0; (j < blen) && (pos < NTFS_COMPBLOCK_SIZE); j++) {
                                       dbuf[pos] = dbuf[pos + boff];
                                       pos++;
                               }
                               cpos += 2;
                       } else {
                               dbuf[pos++] = cbuf[cpos++];
                       }
                       ctag >>= 1;
               }
       }
       return len + 3;
}

int
ntfs_uncompunit(struct ntfsmount *ntmp, u_int8_t *uup, u_int8_t *cup)
{
       int i;
       int off = 0;
       int new;

       for (i = 0; i * NTFS_COMPBLOCK_SIZE < ntfs_cntob(NTFS_COMPUNIT_CL); i++) {
               new = ntfs_uncompblock(uup + i * NTFS_COMPBLOCK_SIZE, cup + off);
               if (new == 0)
                       return (EINVAL);
               off += new;
       }
       return (0);
}