461 lines
11 KiB
C
461 lines
11 KiB
C
/*-
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* Copyright 2003-2005 Colin Percival
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* All rights reserved
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted providing that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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* WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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* DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
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* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*
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* This file is a part of Pcompress, a chunked parallel multi-
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* algorithm lossless compression and decompression program.
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*
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* Copyright (C) 2012 Moinak Ghosh. All rights reserved.
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* Use is subject to license terms.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 3 of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* moinakg@belenix.org, http://moinakg.wordpress.com/
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*
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* This is a somewhat modified bsdiff implementation. It has been modified
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* to do buffer to buffer diffing instead of file to file and also use
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* a custom RLE encoding rather than Bzip2 on the diff output.
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*/
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#if 0
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__FBSDID("$FreeBSD: src/usr.bin/bsdiff/bsdiff/bsdiff.c,v 1.1 2005/08/06 01:59:05 cperciva Exp $");
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#endif
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#include <sys/types.h>
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#include <err.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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#include <allocator.h>
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#include <utils.h>
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#ifdef __USE_SSE_INTRIN__
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#include <emmintrin.h>
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#endif
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#define __IN_BSDIFF__
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#include "bscommon.h"
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#define MIN(x,y) (((x)<(y)) ? (x) : (y))
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static void split(bsize_t *I,bsize_t *V,bsize_t start,bsize_t len,bsize_t h)
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{
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bsize_t i,j,k,x,tmp,jj,kk;
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if(len<16) {
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for(k=start;k<start+len;k+=j) {
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j=1;x=V[I[k]+h];
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for(i=1;k+i<start+len;i++) {
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if(V[I[k+i]+h]<x) {
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x=V[I[k+i]+h];
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j=0;
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};
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if(V[I[k+i]+h]==x) {
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tmp=I[k+j];I[k+j]=I[k+i];I[k+i]=tmp;
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++j;
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};
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};
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for(i=0;i<j;i++) V[I[k+i]]=k+j-1;
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if(j==1) I[k]=-1;
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};
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return;
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};
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x=V[I[start+len/2]+h];
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jj=0;kk=0;
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for(i=start;i<start+len;i++) {
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if(V[I[i]+h]<x) ++jj;
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if(V[I[i]+h]==x) ++kk;
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};
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jj+=start;kk+=jj;
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i=start;j=0;k=0;
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while(i<jj) {
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if(V[I[i]+h]<x) {
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++i;
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} else if(V[I[i]+h]==x) {
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tmp=I[i];I[i]=I[jj+j];I[jj+j]=tmp;
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++j;
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} else {
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tmp=I[i];I[i]=I[kk+k];I[kk+k]=tmp;
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++k;
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};
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};
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while(jj+j<kk) {
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if(V[I[jj+j]+h]==x) {
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++j;
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} else {
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tmp=I[jj+j];I[jj+j]=I[kk+k];I[kk+k]=tmp;
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++k;
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};
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};
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if(jj>start) split(I,V,start,jj-start,h);
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for(i=0;i<kk-jj;i++) V[I[jj+i]]=kk-1;
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if(jj==kk-1) I[jj]=-1;
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if(start+len>kk) split(I,V,kk,start+len-kk,h);
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}
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static void qsufsort(bsize_t *I,bsize_t *V,u_char *oldbuf,bsize_t oldsize)
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{
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bsize_t buckets[257];
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bsize_t *bkts;
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bsize_t i,h,len;
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#ifdef __USE_SSE_INTRIN__
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if (((size_t)buckets & (16 - 1)) == 0) { // 16-byte aligned ?
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int iters;
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uchar_t *pos;
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iters = (256 * sizeof (bsize_t)) / (16 * 4);
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__m128i zero = _mm_setzero_si128 ();
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pos = (uchar_t *)buckets;
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for (i=0; i<iters; i++) {
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_mm_store_si128((__m128i *)pos, zero);
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_mm_store_si128((__m128i *)(pos+16), zero);
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_mm_store_si128((__m128i *)(pos+32), zero);
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_mm_store_si128((__m128i *)(pos+48), zero);
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pos += 64;
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}
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} else {
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#endif
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for(i=0;i<256;i++) buckets[i]=0;
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#ifdef __USE_SSE_INTRIN__
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}
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#endif
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/* We want to do this:
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* for(i=0;i<oldsize;i++) buckets[oldbuf[i]]++;
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* for(i=1;i<256;i++) buckets[i]+=buckets[i-1];
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* for(i=255;i>0;i--) buckets[i]=buckets[i-1];
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* buckets[0]=0;
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*
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* However the code below uses an array larger by 1 element and is able to
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* avoid the 3rd loop.
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*/
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bkts = &buckets[1];
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for(i=0;i<oldsize;i++) bkts[oldbuf[i]]++;
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for(i=1;i<256;i++) bkts[i]+=bkts[i-1];
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buckets[0]=0;
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for(i=0;i<oldsize;i++) I[++buckets[oldbuf[i]]]=i;
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I[0]=oldsize;
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for(i=0;i<oldsize;i++) V[i]=buckets[oldbuf[i]];
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V[oldsize]=0;
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for(i=1;i<256;i++) if(buckets[i]==buckets[i-1]+1) I[buckets[i]]=-1;
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I[0]=-1;
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for(h=1;I[0]!=-(oldsize+1);h+=h) {
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len=0;
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for(i=0;i<oldsize+1;) {
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if(I[i]<0) {
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len-=I[i];
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i-=I[i];
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} else {
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if(len) I[i-len]=-len;
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len=V[I[i]]+1-i;
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split(I,V,i,len,h);
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i+=len;
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len=0;
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};
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};
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if(len) I[i-len]=-len;
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};
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for(i=0;i<oldsize+1;i++) I[V[i]]=i;
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}
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static bsize_t matchlen(u_char *oldbuf,bsize_t oldsize,u_char *newbuf,bsize_t newsize)
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{
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bsize_t i;
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for(i=0;(i<oldsize)&&(i<newsize);i++)
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if(oldbuf[i]!=newbuf[i]) break;
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return i;
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}
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static bsize_t search(bsize_t *I,u_char *oldbuf,bsize_t oldsize,
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u_char *newbuf,bsize_t newsize,bsize_t st,bsize_t en,bsize_t *pos)
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{
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bsize_t x,y;
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if(en-st<2) {
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x=matchlen(oldbuf+I[st],oldsize-I[st],newbuf,newsize);
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y=matchlen(oldbuf+I[en],oldsize-I[en],newbuf,newsize);
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if(x>y) {
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*pos=I[st];
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return x;
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} else {
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*pos=I[en];
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return y;
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}
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};
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x=st+(en-st)/2;
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if(memcmp(oldbuf+I[x],newbuf,MIN(oldsize-I[x],newsize))<0) {
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return search(I,oldbuf,oldsize,newbuf,newsize,x,en,pos);
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} else {
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return search(I,oldbuf,oldsize,newbuf,newsize,st,x,pos);
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};
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}
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static void
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valouti32(bsize_t x, u_char *buf)
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{
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int32_t val;
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val = x;
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*((int32_t *)buf) = htonl(val);
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}
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bsize_t
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bsdiff(u_char *oldbuf, bsize_t oldsize, u_char *newbuf, bsize_t newsize,
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u_char *diff, u_char *scratch, bsize_t scratchsize)
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{
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bsize_t *I,*V;
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bsize_t scan,pos,len;
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bsize_t lastscan,lastpos,lastoffset;
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bsize_t oldscore,scsc;
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bsize_t s,Sf,lenf,Sb,lenb;
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bsize_t overlap,Ss,lens;
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bsize_t i, rv;
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bsize_t dblen,eblen;
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u_char *db,*eb, *cb;
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u_char buf[sizeof (bsize_t)];
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u_char header[48];
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unsigned int sz, hdrsz, ulen;
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bufio_t pf;
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sz = sizeof (bsize_t);
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I = (bsize_t *)slab_alloc(NULL, (oldsize+1)*sz);
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V = (bsize_t *)slab_alloc(NULL, (oldsize+1)*sz);
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if(I == NULL || V == NULL) return (0);
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qsufsort(I,V,oldbuf,oldsize);
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slab_free(NULL, V);
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if(((db=(u_char *)slab_alloc(NULL, newsize+1))==NULL) ||
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((eb=(u_char *)slab_alloc(NULL, newsize+1))==NULL)) {
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fprintf(stderr, "bsdiff: Memory allocation error.\n");
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slab_free(NULL, I);
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slab_free(NULL, V);
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return (0);
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}
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dblen=0;
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eblen=0;
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BUFOPEN(&pf, diff, newsize);
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/* Header is
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0 4 compressed length of ctrl block
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4 4 actual length of ctrl block
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8 4 compressed length of diff block
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12 4 actual length of diff block
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16 4 compressed length of extra block
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20 4 actual length of extra block
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24 4 length of new file */
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/* File is
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0 28 Header
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28 ?? ctrl block
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?? ?? diff block
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?? ?? extra block */
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valouti32(0, header);
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valouti32(0, header + 4);
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valouti32(0, header + 4*2);
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valouti32(0, header + 4*3);
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valouti32(0, header + 4*4);
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valouti32(0, header + 4*5);
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valouti32(newsize, header + 4*6);
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if (BUFWRITE(&pf, header, 4*7) != 4*7) {
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fprintf(stderr, "bsdiff: Write to compressed buffer failed.\n");
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rv = 0;
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goto out;
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}
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hdrsz = 4*7;
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/* Compute the differences, writing ctrl as we go */
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scan=0;len=0;
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lastscan=0;lastpos=0;lastoffset=0;
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pos=0;
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while(scan<newsize) {
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oldscore=0;
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for(scsc=scan+=len;scan<newsize;scan++) {
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len=search(I,oldbuf,oldsize,newbuf+scan,newsize-scan,
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0,oldsize,&pos);
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for(;scsc<scan+len;scsc++)
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oldscore += ((scsc+lastoffset<oldsize) &&
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(oldbuf[scsc+lastoffset] == newbuf[scsc]));
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if(((len==oldscore) && (len!=0)) ||
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(len>oldscore+sz)) break;
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if((scan+lastoffset<oldsize) &&
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(oldbuf[scan+lastoffset] == newbuf[scan]))
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oldscore--;
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};
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if((len!=oldscore) || (scan==newsize)) {
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s=0;Sf=0;lenf=0;
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for(i=0;(lastscan+i<scan)&&(lastpos+i<oldsize);) {
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s += (oldbuf[lastpos+i]==newbuf[lastscan+i]);
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++i;
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if(s*2-i>Sf*2-lenf) { Sf=s; lenf=i; };
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};
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lenb=0;
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if(scan<newsize) {
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s=0;Sb=0;
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for(i=1;(scan>=lastscan+i)&&(pos>=i);i++) {
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s += (oldbuf[pos-i]==newbuf[scan-i]);
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if(s*2-i>Sb*2-lenb) { Sb=s; lenb=i; };
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};
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};
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if(lastscan+lenf>scan-lenb) {
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overlap=(lastscan+lenf)-(scan-lenb);
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s=0;Ss=0;lens=0;
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for(i=0;i<overlap;i++) {
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s += (newbuf[lastscan+lenf-overlap+i]==
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oldbuf[lastpos+lenf-overlap+i]);
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s -= (newbuf[scan-lenb+i]==oldbuf[pos-lenb+i]);
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if(s>Ss) { Ss=s; lens=i+1; };
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};
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lenf+=lens-overlap;
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lenb-=lens;
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};
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for(i=0;i<lenf;i++)
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db[dblen+i]=newbuf[lastscan+i]-oldbuf[lastpos+i];
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for(i=0;i<(scan-lenb)-(lastscan+lenf);i++)
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eb[eblen+i]=newbuf[lastscan+lenf+i];
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dblen+=lenf;
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eblen+=(scan-lenb)-(lastscan+lenf);
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valouti32(lenf, buf);
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BUFWRITE(&pf, buf, 4);
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valouti32((scan-lenb)-(lastscan+lenf),buf);
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BUFWRITE(&pf, buf, 4);
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valouti32((pos-lenb)-(lastpos+lenf),buf);
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BUFWRITE(&pf, buf, 4);
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lastscan=scan-lenb;
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lastpos=pos-lenb;
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lastoffset=pos-scan;
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}
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}
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if (eblen > (newsize/2 + newsize/5)) {
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rv = 0;
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goto out;
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}
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/* Compute uncompressed size of the ctrl data. */
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len = BUFTELL(&pf);
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valouti32(len-hdrsz, header+4);
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ulen = len-hdrsz;
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/* If our data can fit in the scratch area use it otherwise alloc. */
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if (ulen > scratchsize) {
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cb = (u_char *)slab_alloc(NULL, ulen);
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} else {
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cb = scratch;
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}
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/*
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* Attempt to RLE the ctrl data. If RLE succeeds and produces a smaller
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* data then retain it.
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*/
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BUFSEEK(&pf, hdrsz, SEEK_SET);
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rv = zero_rle_encode(BUFPTR(&pf), ulen, cb, &ulen);
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if (rv == 0 && ulen < len-hdrsz) {
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BUFWRITE(&pf, cb, ulen);
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} else {
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BUFSEEK(&pf, len, SEEK_SET);
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}
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if (len-hdrsz > scratchsize) {
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slab_free(NULL, cb);
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}
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/* Compute compressed size of ctrl data */
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len = BUFTELL(&pf);
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valouti32(len-hdrsz, header);
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rv = len;
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/* Write diff data */
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len = newsize - rv;
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ulen = len;
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if (zero_rle_encode(db, dblen, BUFPTR(&pf), &ulen) == -1) {
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rv = 0;
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goto out;
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}
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/* Output size of diff data */
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len = ulen;
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valouti32(len, header + 4*2);
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valouti32(dblen, header + 4*3);
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rv += len;
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BUFSEEK(&pf, len, SEEK_CUR);
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/* Write extra data */
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len = newsize - rv;
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ulen = len;
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if (zero_rle_encode(eb, eblen, BUFPTR(&pf), &ulen) == -1) {
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rv = 0;
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goto out;
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}
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/* Output size of extra data */
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len = ulen;
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valouti32(len, header + 4*4);
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valouti32(eblen, header + 4*5);
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rv += len;
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/* Seek to the beginning, re-write the header.*/
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BUFSEEK(&pf, 0, SEEK_SET);
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BUFWRITE(&pf, header, hdrsz);
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out:
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/* Free the memory we used */
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slab_free(NULL, db);
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slab_free(NULL, eb);
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slab_free(NULL, I);
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return (rv);
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}
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