353 lines
10 KiB
C++
353 lines
10 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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#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 "bsdiff/bsdiff.h"
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#include <sys/types.h>
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#include <bzlib.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 <algorithm>
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namespace bsdiff {
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static off_t matchlen(const u_char* old, off_t oldsize, const u_char* new_buf,
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off_t newsize) {
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off_t i;
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for(i=0;(i<oldsize)&&(i<newsize);i++)
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if(old[i]!=new_buf[i]) break;
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return i;
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}
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// This is a binary search of the string |new_buf| of size |newsize| (or a
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// prefix of it) in the |old| string with size |oldsize| using the suffix array
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// |I|. |st| and |en| is the start and end of the search range (inclusive).
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// Returns the length of the longest prefix found and stores the position of the
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// string found in |*pos|.
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static off_t search(saidx_t* I, const u_char* old, off_t oldsize,
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const u_char* new_buf, off_t newsize, off_t st, off_t en,
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off_t* pos) {
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off_t x,y;
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if(en-st<2) {
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x=matchlen(old+I[st],oldsize-I[st],new_buf,newsize);
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y=matchlen(old+I[en],oldsize-I[en],new_buf,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(old+I[x],new_buf,std::min(oldsize-I[x],newsize))<=0) {
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return search(I,old,oldsize,new_buf,newsize,x,en,pos);
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} else {
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return search(I,old,oldsize,new_buf,newsize,st,x,pos);
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};
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}
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static void offtout(off_t x,u_char *buf)
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{
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off_t y;
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if(x<0) y=-x; else y=x;
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buf[0]=y%256;y-=buf[0];
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y=y/256;buf[1]=y%256;y-=buf[1];
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y=y/256;buf[2]=y%256;y-=buf[2];
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y=y/256;buf[3]=y%256;y-=buf[3];
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y=y/256;buf[4]=y%256;y-=buf[4];
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y=y/256;buf[5]=y%256;y-=buf[5];
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y=y/256;buf[6]=y%256;y-=buf[6];
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y=y/256;buf[7]=y%256;
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if(x<0) buf[7]|=0x80;
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}
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int bsdiff(const char* old_filename, const char* new_filename,
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const char* patch_filename) {
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int fd;
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u_char *old_buf,*new_buf;
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off_t oldsize,newsize;
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/* Allocate oldsize+1 bytes instead of oldsize bytes to ensure
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that we never try to malloc(0) and get a NULL pointer */
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if(((fd=open(old_filename,O_RDONLY,0))<0) ||
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((oldsize=lseek(fd,0,SEEK_END))==-1) ||
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((old_buf=static_cast<u_char*>(malloc(oldsize+1)))==NULL) ||
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(lseek(fd,0,SEEK_SET)!=0) ||
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(read(fd,old_buf,oldsize)!=oldsize) ||
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(close(fd)==-1)) err(1,"%s",old_filename);
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/* Allocate newsize+1 bytes instead of newsize bytes to ensure
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that we never try to malloc(0) and get a NULL pointer */
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if(((fd=open(new_filename,O_RDONLY,0))<0) ||
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((newsize=lseek(fd,0,SEEK_END))==-1) ||
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((new_buf = static_cast<u_char*>(malloc(newsize+1)))==NULL) ||
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(lseek(fd,0,SEEK_SET)!=0) ||
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(read(fd,new_buf,newsize)!=newsize) ||
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(close(fd)==-1)) err(1,"%s",new_filename);
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int ret = bsdiff(old_buf, oldsize, new_buf, newsize, patch_filename, nullptr);
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free(old_buf);
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free(new_buf);
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return ret;
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}
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// Generate bsdiff patch from |old_buf| to |new_buf|, save the patch file to
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// |patch_filename|. Returns 0 on success.
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// |I_cache| can be used to cache the suffix array if the same |old_buf| is used
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// repeatedly, pass nullptr if not needed.
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int bsdiff(const u_char* old_buf, off_t oldsize, const u_char* new_buf,
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off_t newsize, const char* patch_filename, saidx_t** I_cache) {
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saidx_t *I;
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off_t scan,pos=0,len;
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off_t lastscan,lastpos,lastoffset;
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off_t oldscore,scsc;
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off_t s,Sf,lenf,Sb,lenb;
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off_t overlap,Ss,lens;
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off_t i;
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off_t dblen,eblen;
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u_char *db,*eb;
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u_char buf[8];
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u_char header[32];
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FILE * pf;
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BZFILE * pfbz2;
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int bz2err;
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if (I_cache && *I_cache) {
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I = *I_cache;
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} else {
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if ((I=static_cast<saidx_t*>(malloc((oldsize+1)*sizeof(saidx_t))))==NULL)
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err(1,NULL);
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if (divsufsort(old_buf, I, oldsize)) err(1, "divsufsort");
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if (I_cache)
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*I_cache = I;
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}
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if(((db=static_cast<u_char*>(malloc(newsize+1)))==NULL) ||
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((eb=static_cast<u_char*>(malloc(newsize+1)))==NULL)) err(1,NULL);
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dblen=0;
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eblen=0;
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/* Create the patch file */
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if ((pf = fopen(patch_filename, "w")) == NULL)
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err(1, "%s", patch_filename);
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/* Header is
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0 8 "BSDIFF40"
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8 8 length of bzip2ed ctrl block
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16 8 length of bzip2ed diff block
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24 8 length of new file */
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/* File is
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0 32 Header
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32 ?? Bzip2ed ctrl block
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?? ?? Bzip2ed diff block
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?? ?? Bzip2ed extra block */
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memcpy(header,"BSDIFF40",8);
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offtout(0, header + 8);
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offtout(0, header + 16);
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offtout(newsize, header + 24);
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if (fwrite(header, 32, 1, pf) != 1)
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err(1, "fwrite(%s)", patch_filename);
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/* Compute the differences, writing ctrl as we go */
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if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
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errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
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scan=0;len=0;
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lastscan=0;lastpos=0;lastoffset=0;
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while(scan<newsize) {
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oldscore=0;
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/* If we come across a large block of data that only differs
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* by less than 8 bytes, this loop will take a long time to
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* go past that block of data. We need to track the number of
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* times we're stuck in the block and break out of it. */
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int num_less_than_eight = 0;
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off_t prev_len, prev_oldscore, prev_pos;
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for(scsc=scan+=len;scan<newsize;scan++) {
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prev_len=len;
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prev_oldscore=oldscore;
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prev_pos=pos;
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len=search(I,old_buf,oldsize,new_buf+scan,newsize-scan,
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0,oldsize-1,&pos);
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for(;scsc<scan+len;scsc++)
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if((scsc+lastoffset<oldsize) &&
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(old_buf[scsc+lastoffset] == new_buf[scsc]))
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oldscore++;
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if(((len==oldscore) && (len!=0)) ||
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(len>oldscore+8)) break;
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if((scan+lastoffset<oldsize) &&
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(old_buf[scan+lastoffset] == new_buf[scan]))
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oldscore--;
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const off_t fuzz = 8;
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if (prev_len-fuzz<=len && len<=prev_len &&
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prev_oldscore-fuzz<=oldscore &&
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oldscore<=prev_oldscore &&
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prev_pos<=pos && pos <=prev_pos+fuzz &&
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oldscore<=len && len<=oldscore+fuzz)
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++num_less_than_eight;
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else
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num_less_than_eight=0;
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if (num_less_than_eight > 100) break;
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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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if(old_buf[lastpos+i]==new_buf[lastscan+i]) s++;
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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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if(old_buf[pos-i]==new_buf[scan-i]) s++;
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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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if(new_buf[lastscan+lenf-overlap+i]==
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old_buf[lastpos+lenf-overlap+i]) s++;
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if(new_buf[scan-lenb+i]==
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old_buf[pos-lenb+i]) s--;
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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]=new_buf[lastscan+i]-old_buf[lastpos+i];
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for(i=0;i<(scan-lenb)-(lastscan+lenf);i++)
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eb[eblen+i]=new_buf[lastscan+lenf+i];
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dblen+=lenf;
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eblen+=(scan-lenb)-(lastscan+lenf);
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offtout(lenf,buf);
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BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
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if (bz2err != BZ_OK)
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errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
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offtout((scan-lenb)-(lastscan+lenf),buf);
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BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
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if (bz2err != BZ_OK)
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errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
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offtout((pos-lenb)-(lastpos+lenf),buf);
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BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
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if (bz2err != BZ_OK)
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errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
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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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BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
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if (bz2err != BZ_OK)
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errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
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/* Compute size of compressed ctrl data */
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if ((len = ftello(pf)) == -1)
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err(1, "ftello");
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offtout(len-32, header + 8);
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/* Write compressed diff data */
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if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
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errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
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BZ2_bzWrite(&bz2err, pfbz2, db, dblen);
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if (bz2err != BZ_OK)
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errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
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BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
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if (bz2err != BZ_OK)
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errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
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/* Compute size of compressed diff data */
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if ((newsize = ftello(pf)) == -1)
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err(1, "ftello");
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offtout(newsize - len, header + 16);
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/* Write compressed extra data */
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if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
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errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
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BZ2_bzWrite(&bz2err, pfbz2, eb, eblen);
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if (bz2err != BZ_OK)
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errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
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BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
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if (bz2err != BZ_OK)
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errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
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/* Seek to the beginning, write the header, and close the file */
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if (fseeko(pf, 0, SEEK_SET))
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err(1, "fseeko");
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if (fwrite(header, 32, 1, pf) != 1)
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err(1, "fwrite(%s)", patch_filename);
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if (fclose(pf))
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err(1, "fclose");
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/* Free the memory we used */
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free(db);
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free(eb);
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if (I_cache == nullptr)
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free(I);
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return 0;
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}
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} // namespace bsdiff
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