tor-browser

bsdiff.c (9069B)

---

/* vim:set ts=8 sw=8 sts=8 noet: */
/*
 bsdiff.c -- Binary patch generator.

 Copyright 2003 Colin Percival

 For the terms under which this work may be distributed, please see
 the adjoining file "LICENSE".

 ChangeLog:
 2005-05-05 - Use the modified header struct from bspatch.h; use 32-bit
              values throughout.
                --Benjamin Smedberg <benjamin@smedbergs.us>
 2005-05-18 - Use the same CRC algorithm as bzip2, and leverage the CRC table
              provided by libbz2.
                --Darin Fisher <darin@meer.net>
*/

#include "bspatch.h"

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <stdarg.h>
#ifdef XP_WIN
#include <io.h>
#include <winsock2.h>
#define open _open
#define close _close
#define read _read
#define lseek _lseek
#define write _write
#else
#include <unistd.h>
#include <arpa/inet.h>
#define _O_BINARY 0
#endif

#include "crctable.h"

#undef MIN
#define MIN(x,y) (((x)<(y)) ? (x) : (y))

/*---------------------------------------------------------------------------*/

/* This variable lives in libbz2.  It's declared in bzlib_private.h, so we just
* declare it here to avoid including that entire header file.
*/
extern unsigned int BZ2_crc32Table[256];

static unsigned int
crc32(const unsigned char *buf, unsigned int len)
{
unsigned int crc = 0xffffffffL;

const unsigned char *end = buf + len;
for (; buf != end; ++buf)
	crc = (crc << 8) ^ BZ2_crc32Table[(crc >> 24) ^ *buf];

crc = ~crc;
return crc;
}

/*---------------------------------------------------------------------------*/

static void
reporterr(int e, const char *fmt, ...)
{
if (fmt) {
	va_list args;
	va_start(args, fmt);
	vfprintf(stderr, fmt, args);
	va_end(args);
}

exit(e);
}

static void
split(int32_t *I,int32_t *V,int32_t start,int32_t len,int32_t h)
{
int32_t i,j,k,x,tmp,jj,kk;

if(len<16) {
	for(k=start;k<start+len;k+=j) {
		j=1;x=V[I[k]+h];
		for(i=1;k+i<start+len;i++) {
			if(V[I[k+i]+h]<x) {
				x=V[I[k+i]+h];
				j=0;
			};
			if(V[I[k+i]+h]==x) {
				tmp=I[k+j];I[k+j]=I[k+i];I[k+i]=tmp;
				j++;
			};
		};
		for(i=0;i<j;i++) V[I[k+i]]=k+j-1;
		if(j==1) I[k]=-1;
	};
	return;
};

x=V[I[start+len/2]+h];
jj=0;kk=0;
for(i=start;i<start+len;i++) {
	if(V[I[i]+h]<x) jj++;
	if(V[I[i]+h]==x) kk++;
};
jj+=start;kk+=jj;

i=start;j=0;k=0;
while(i<jj) {
	if(V[I[i]+h]<x) {
		i++;
	} else if(V[I[i]+h]==x) {
		tmp=I[i];I[i]=I[jj+j];I[jj+j]=tmp;
		j++;
	} else {
		tmp=I[i];I[i]=I[kk+k];I[kk+k]=tmp;
		k++;
	};
};

while(jj+j<kk) {
	if(V[I[jj+j]+h]==x) {
		j++;
	} else {
		tmp=I[jj+j];I[jj+j]=I[kk+k];I[kk+k]=tmp;
		k++;
	};
};

if(jj>start) split(I,V,start,jj-start,h);

for(i=0;i<kk-jj;i++) V[I[jj+i]]=kk-1;
if(jj==kk-1) I[jj]=-1;

if(start+len>kk) split(I,V,kk,start+len-kk,h);
}

static void
qsufsort(int32_t *I,int32_t *V,unsigned char *old,int32_t oldsize)
{
int32_t buckets[256];
int32_t i,h,len;

for(i=0;i<256;i++) buckets[i]=0;
for(i=0;i<oldsize;i++) buckets[old[i]]++;
for(i=1;i<256;i++) buckets[i]+=buckets[i-1];
for(i=255;i>0;i--) buckets[i]=buckets[i-1];
buckets[0]=0;

for(i=0;i<oldsize;i++) I[++buckets[old[i]]]=i;
I[0]=oldsize;
for(i=0;i<oldsize;i++) V[i]=buckets[old[i]];
V[oldsize]=0;
for(i=1;i<256;i++) if(buckets[i]==buckets[i-1]+1) I[buckets[i]]=-1;
I[0]=-1;

for(h=1;I[0]!=-(oldsize+1);h+=h) {
	len=0;
	for(i=0;i<oldsize+1;) {
		if(I[i]<0) {
			len-=I[i];
			i-=I[i];
		} else {
			if(len) I[i-len]=-len;
			len=V[I[i]]+1-i;
			split(I,V,i,len,h);
			i+=len;
			len=0;
		};
	};
	if(len) I[i-len]=-len;
};

for(i=0;i<oldsize+1;i++) I[V[i]]=i;
}

static int32_t
matchlen(unsigned char *old,int32_t oldsize,unsigned char *newbuf,int32_t newsize)
{
int32_t i;

for(i=0;(i<oldsize)&&(i<newsize);i++)
	if(old[i]!=newbuf[i]) break;

return i;
}

static int32_t
search(int32_t *I,unsigned char *old,int32_t oldsize,
      unsigned char *newbuf,int32_t newsize,int32_t st,int32_t en,int32_t *pos)
{
int32_t x,y;

if(en-st<2) {
	x=matchlen(old+I[st],oldsize-I[st],newbuf,newsize);
	y=matchlen(old+I[en],oldsize-I[en],newbuf,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],newbuf,MIN(oldsize-I[x],newsize))<0) {
	return search(I,old,oldsize,newbuf,newsize,x,en,pos);
} else {
	return search(I,old,oldsize,newbuf,newsize,st,x,pos);
};
}

int main(int argc,char *argv[])
{
int fd;
unsigned char *old,*newbuf;
int32_t oldsize,newsize;
int32_t *I,*V;

int32_t scan,pos,len;
int32_t lastscan,lastpos,lastoffset;
int32_t oldscore,scsc;

int32_t s,Sf,lenf,Sb,lenb;
int32_t overlap,Ss,lens;
int32_t i;

int32_t dblen,eblen;
unsigned char *db,*eb;

unsigned int scrc;

MBSPatchHeader header = {
	{'M','B','D','I','F','F','1','0'},
	0, 0, 0, 0, 0, 0
};

uint32_t numtriples;

if(argc!=4)
	reporterr(1,"usage: %s <oldfile> <newfile> <patchfile>\n",argv[0]);

/* 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(argv[1],O_RDONLY|_O_BINARY,0))<0) ||
	((oldsize=lseek(fd,0,SEEK_END))==-1) ||
	((old=(unsigned char*) malloc(oldsize+1))==NULL) ||
	(lseek(fd,0,SEEK_SET)!=0) ||
	(read(fd,old,oldsize)!=oldsize) ||
	(close(fd)==-1))
	reporterr(1,"%s\n",argv[1]);

scrc = crc32(old, oldsize);

if(((I=(int32_t*) malloc((oldsize+1)*sizeof(int32_t)))==NULL) ||
	((V=(int32_t*) malloc((oldsize+1)*sizeof(int32_t)))==NULL))
	reporterr(1,NULL);

qsufsort(I,V,old,oldsize);

free(V);

/* 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(argv[2],O_RDONLY|_O_BINARY,0))<0) ||
	((newsize=lseek(fd,0,SEEK_END))==-1) ||
	((newbuf=(unsigned char*) malloc(newsize+1))==NULL) ||
	(lseek(fd,0,SEEK_SET)!=0) ||
	(read(fd,newbuf,newsize)!=newsize) ||
	(close(fd)==-1)) reporterr(1,"%s\n",argv[2]);

if(((db=(unsigned char*) malloc(newsize+1))==NULL) ||
	((eb=(unsigned char*) malloc(newsize+1))==NULL))
	reporterr(1,NULL);

dblen=0;
eblen=0;

if((fd=open(argv[3],O_CREAT|O_TRUNC|O_WRONLY|_O_BINARY,0666))<0)
	reporterr(1,"%s\n",argv[3]);

/* start writing here */

/* We don't know the lengths yet, so we will write the header again
	 at the end */

if(write(fd,&header,sizeof(MBSPatchHeader))!=sizeof(MBSPatchHeader))
	reporterr(1,"%s\n",argv[3]);

scan=0;len=0;
lastscan=0;lastpos=0;lastoffset=0;
numtriples = 0;
while(scan<newsize) {
	oldscore=0;

	for(scsc=scan+=len;scan<newsize;scan++) {
		len=search(I,old,oldsize,newbuf+scan,newsize-scan,
				0,oldsize,&pos);

		for(;scsc<scan+len;scsc++)
		if((scsc+lastoffset<oldsize) &&
			(old[scsc+lastoffset] == newbuf[scsc]))
			oldscore++;

		if(((len==oldscore) && (len!=0)) || 
			(len>oldscore+10)) break;

		if((scan+lastoffset<oldsize) &&
			(old[scan+lastoffset] == newbuf[scan]))
			oldscore--;
	};

	if((len!=oldscore) || (scan==newsize)) {
		MBSPatchTriple triple;

		s=0;Sf=0;lenf=0;
		for(i=0;(lastscan+i<scan)&&(lastpos+i<oldsize);) {
			if(old[lastpos+i]==newbuf[lastscan+i]) s++;
			i++;
			if(s*3-i*2>Sf*3-lenf*2) { Sf=s; lenf=i; };
		};

		lenb=0;
		if(scan<newsize) {
			s=0;Sb=0;
			for(i=1;(scan>=lastscan+i)&&(pos>=i);i++) {
				if(old[pos-i]==newbuf[scan-i]) s++;
				if(s*3-i*2>Sb*3-lenb*2) { 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(newbuf[lastscan+lenf-overlap+i]==
				   old[lastpos+lenf-overlap+i]) s++;
				if(newbuf[scan-lenb+i]==
				   old[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]=newbuf[lastscan+i]-old[lastpos+i];
		for(i=0;i<(scan-lenb)-(lastscan+lenf);i++)
			eb[eblen+i]=newbuf[lastscan+lenf+i];

		dblen+=lenf;
		eblen+=(scan-lenb)-(lastscan+lenf);

		triple.x = htonl(lenf);
		triple.y = htonl((scan-lenb)-(lastscan+lenf));
		triple.z = htonl((pos-lenb)-(lastpos+lenf));
		if (write(fd,&triple,sizeof(triple)) != sizeof(triple))
			reporterr(1,NULL);

#ifdef DEBUG_bsmedberg
		printf("Writing a block:\n"
		       "	X: %u\n"
		       "	Y: %u\n"
		       "	Z: %i\n",
		       (uint32_t) lenf,
		       (uint32_t) ((scan-lenb)-(lastscan+lenf)),
		       (uint32_t) ((pos-lenb)-(lastpos+lenf)));
#endif

		++numtriples;

		lastscan=scan-lenb;
		lastpos=pos-lenb;
		lastoffset=pos-scan;
	};
};

if(write(fd,db,dblen)!=dblen)
	reporterr(1,NULL);

if(write(fd,eb,eblen)!=eblen)
	reporterr(1,NULL);

header.slen	= htonl(oldsize);
header.scrc32	= htonl(scrc);
header.dlen	= htonl(newsize);
header.cblen	= htonl(numtriples * sizeof(MBSPatchTriple));
header.difflen	= htonl(dblen);
header.extralen = htonl(eblen);

if (lseek(fd,0,SEEK_SET) == -1 ||
    write(fd,&header,sizeof(header)) != sizeof(header) ||
    close(fd) == -1)
	reporterr(1,NULL);

free(db);
free(eb);
free(I);
free(old);
free(newbuf);

return 0;
}