/*-
* Copyright 2003-2005 Colin Percival
* All rights reserved
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted providing 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 ``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 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.
*/
#if 0
__FBSDID("$FreeBSD: src/usr.bin/bsdiff/bsdiff/bsdiff.c,v 1.1 2005/08/06 01:59:05 cperciva Exp $");
#endif
#include "bsdiff.h"
#include <sys/types.h>
#include <bzlib.h>
#include <err.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <algorithm>
namespace bsdiff {
static off_t matchlen(const u_char* old, off_t oldsize, const u_char* new_buf,
off_t newsize) {
off_t i;
for(i=0;(i<oldsize)&&(i<newsize);i++)
if(old[i]!=new_buf[i]) break;
return i;
}
// This is a binary search of the string |new_buf| of size |newsize| (or a
// prefix of it) in the |old| string with size |oldsize| using the suffix array
// |I|. |st| and |en| is the start and end of the search range (inclusive).
// Returns the length of the longest prefix found and stores the position of the
// string found in |*pos|.
static off_t search(saidx_t* I, const u_char* old, off_t oldsize,
const u_char* new_buf, off_t newsize, off_t st, off_t en,
off_t* pos) {
off_t x,y;
if(en-st<2) {
x=matchlen(old+I[st],oldsize-I[st],new_buf,newsize);
y=matchlen(old+I[en],oldsize-I[en],new_buf,newsize);
if(x>y) {
*pos=I[st];
return x;
} else {
*pos=I[en];
return y;
}
};
x=st+(en-st)/2;
if(memcmp(old+I[x],new_buf,std::min(oldsize-I[x],newsize))<=0) {
return search(I,old,oldsize,new_buf,newsize,x,en,pos);
} else {
return search(I,old,oldsize,new_buf,newsize,st,x,pos);
};
}
static void offtout(off_t x,u_char *buf)
{
off_t y;
if(x<0) y=-x; else y=x;
buf[0]=y%256;y-=buf[0];
y=y/256;buf[1]=y%256;y-=buf[1];
y=y/256;buf[2]=y%256;y-=buf[2];
y=y/256;buf[3]=y%256;y-=buf[3];
y=y/256;buf[4]=y%256;y-=buf[4];
y=y/256;buf[5]=y%256;y-=buf[5];
y=y/256;buf[6]=y%256;y-=buf[6];
y=y/256;buf[7]=y%256;
if(x<0) buf[7]|=0x80;
}
int bsdiff(const char* old_filename, const char* new_filename,
const char* patch_filename) {
int fd;
u_char *old_buf,*new_buf;
off_t oldsize,newsize;
/* Allocate oldsize+1 bytes instead of oldsize bytes to ensure
that we never try to malloc(0) and get a NULL pointer */
if(((fd=open(old_filename,O_RDONLY,0))<0) ||
((oldsize=lseek(fd,0,SEEK_END))==-1) ||
((old_buf=static_cast<u_char*>(malloc(oldsize+1)))==NULL) ||
(lseek(fd,0,SEEK_SET)!=0) ||
(read(fd,old_buf,oldsize)!=oldsize) ||
(close(fd)==-1)) err(1,"%s",old_filename);
/* Allocate newsize+1 bytes instead of newsize bytes to ensure
that we never try to malloc(0) and get a NULL pointer */
if(((fd=open(new_filename,O_RDONLY,0))<0) ||
((newsize=lseek(fd,0,SEEK_END))==-1) ||
((new_buf = static_cast<u_char*>(malloc(newsize+1)))==NULL) ||
(lseek(fd,0,SEEK_SET)!=0) ||
(read(fd,new_buf,newsize)!=newsize) ||
(close(fd)==-1)) err(1,"%s",new_filename);
int ret = bsdiff(old_buf, oldsize, new_buf, newsize, patch_filename, nullptr);
free(old_buf);
free(new_buf);
return ret;
}
// Generate bsdiff patch from |old_buf| to |new_buf|, save the patch file to
// |patch_filename|. Returns 0 on success.
// |I_cache| can be used to cache the suffix array if the same |old_buf| is used
// repeatedly, pass nullptr if not needed.
int bsdiff(const u_char* old_buf, off_t oldsize, const u_char* new_buf,
off_t newsize, const char* patch_filename, saidx_t** I_cache) {
saidx_t *I;
off_t scan,pos=0,len;
off_t lastscan,lastpos,lastoffset;
off_t oldscore,scsc;
off_t s,Sf,lenf,Sb,lenb;
off_t overlap,Ss,lens;
off_t i;
off_t dblen,eblen;
u_char *db,*eb;
u_char buf[8];
u_char header[32];
FILE * pf;
BZFILE * pfbz2;
int bz2err;
if (I_cache && *I_cache) {
I = *I_cache;
} else {
if ((I=static_cast<saidx_t*>(malloc((oldsize+1)*sizeof(saidx_t))))==NULL)
err(1,NULL);
if (divsufsort(old_buf, I, oldsize)) err(1, "divsufsort");
if (I_cache)
*I_cache = I;
}
if(((db=static_cast<u_char*>(malloc(newsize+1)))==NULL) ||
((eb=static_cast<u_char*>(malloc(newsize+1)))==NULL)) err(1,NULL);
dblen=0;
eblen=0;
/* Create the patch file */
if ((pf = fopen(patch_filename, "w")) == NULL)
err(1, "%s", patch_filename);
/* Header is
0 8 "BSDIFF40"
8 8 length of bzip2ed ctrl block
16 8 length of bzip2ed diff block
24 8 length of new file */
/* File is
0 32 Header
32 ?? Bzip2ed ctrl block
?? ?? Bzip2ed diff block
?? ?? Bzip2ed extra block */
memcpy(header,"BSDIFF40",8);
offtout(0, header + 8);
offtout(0, header + 16);
offtout(newsize, header + 24);
if (fwrite(header, 32, 1, pf) != 1)
err(1, "fwrite(%s)", patch_filename);
/* Compute the differences, writing ctrl as we go */
if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
scan=0;len=0;
lastscan=0;lastpos=0;lastoffset=0;
while(scan<newsize) {
oldscore=0;
/* If we come across a large block of data that only differs
* by less than 8 bytes, this loop will take a long time to
* go past that block of data. We need to track the number of
* times we're stuck in the block and break out of it. */
int num_less_than_eight = 0;
off_t prev_len, prev_oldscore, prev_pos;
for(scsc=scan+=len;scan<newsize;scan++) {
prev_len=len;
prev_oldscore=oldscore;
prev_pos=pos;
len=search(I,old_buf,oldsize,new_buf+scan,newsize-scan,
0,oldsize-1,&pos);
for(;scsc<scan+len;scsc++)
if((scsc+lastoffset<oldsize) &&
(old_buf[scsc+lastoffset] == new_buf[scsc]))
oldscore++;
if(((len==oldscore) && (len!=0)) ||
(len>oldscore+8)) break;
if((scan+lastoffset<oldsize) &&
(old_buf[scan+lastoffset] == new_buf[scan]))
oldscore--;
const off_t fuzz = 8;
if (prev_len-fuzz<=len && len<=prev_len &&
prev_oldscore-fuzz<=oldscore &&
oldscore<=prev_oldscore &&
prev_pos<=pos && pos <=prev_pos+fuzz &&
oldscore<=len && len<=oldscore+fuzz)
++num_less_than_eight;
else
num_less_than_eight=0;
if (num_less_than_eight > 100) break;
};
if((len!=oldscore) || (scan==newsize)) {
s=0;Sf=0;lenf=0;
for(i=0;(lastscan+i<scan)&&(lastpos+i<oldsize);) {
if(old_buf[lastpos+i]==new_buf[lastscan+i]) s++;
i++;
if(s*2-i>Sf*2-lenf) { Sf=s; lenf=i; };
};
lenb=0;
if(scan<newsize) {
s=0;Sb=0;
for(i=1;(scan>=lastscan+i)&&(pos>=i);i++) {
if(old_buf[pos-i]==new_buf[scan-i]) s++;
if(s*2-i>Sb*2-lenb) { Sb=s; lenb=i; };
};
};
if(lastscan+lenf>scan-lenb) {
overlap=(lastscan+lenf)-(scan-lenb);
s=0;Ss=0;lens=0;
for(i=0;i<overlap;i++) {
if(new_buf[lastscan+lenf-overlap+i]==
old_buf[lastpos+lenf-overlap+i]) s++;
if(new_buf[scan-lenb+i]==
old_buf[pos-lenb+i]) s--;
if(s>Ss) { Ss=s; lens=i+1; };
};
lenf+=lens-overlap;
lenb-=lens;
};
for(i=0;i<lenf;i++)
db[dblen+i]=new_buf[lastscan+i]-old_buf[lastpos+i];
for(i=0;i<(scan-lenb)-(lastscan+lenf);i++)
eb[eblen+i]=new_buf[lastscan+lenf+i];
dblen+=lenf;
eblen+=(scan-lenb)-(lastscan+lenf);
offtout(lenf,buf);
BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
if (bz2err != BZ_OK)
errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
offtout((scan-lenb)-(lastscan+lenf),buf);
BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
if (bz2err != BZ_OK)
errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
offtout((pos-lenb)-(lastpos+lenf),buf);
BZ2_bzWrite(&bz2err, pfbz2, buf, 8);
if (bz2err != BZ_OK)
errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
lastscan=scan-lenb;
lastpos=pos-lenb;
lastoffset=pos-scan;
};
};
BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
if (bz2err != BZ_OK)
errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
/* Compute size of compressed ctrl data */
if ((len = ftello(pf)) == -1)
err(1, "ftello");
offtout(len-32, header + 8);
/* Write compressed diff data */
if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
BZ2_bzWrite(&bz2err, pfbz2, db, dblen);
if (bz2err != BZ_OK)
errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
if (bz2err != BZ_OK)
errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
/* Compute size of compressed diff data */
if ((newsize = ftello(pf)) == -1)
err(1, "ftello");
offtout(newsize - len, header + 16);
/* Write compressed extra data */
if ((pfbz2 = BZ2_bzWriteOpen(&bz2err, pf, 9, 0, 0)) == NULL)
errx(1, "BZ2_bzWriteOpen, bz2err = %d", bz2err);
BZ2_bzWrite(&bz2err, pfbz2, eb, eblen);
if (bz2err != BZ_OK)
errx(1, "BZ2_bzWrite, bz2err = %d", bz2err);
BZ2_bzWriteClose(&bz2err, pfbz2, 0, NULL, NULL);
if (bz2err != BZ_OK)
errx(1, "BZ2_bzWriteClose, bz2err = %d", bz2err);
/* Seek to the beginning, write the header, and close the file */
if (fseeko(pf, 0, SEEK_SET))
err(1, "fseeko");
if (fwrite(header, 32, 1, pf) != 1)
err(1, "fwrite(%s)", patch_filename);
if (fclose(pf))
err(1, "fclose");
/* Free the memory we used */
free(db);
free(eb);
if (I_cache == nullptr)
free(I);
return 0;
}
} // namespace bsdiff