michael@0: /* vim:set ts=8 sw=8 sts=8 noet: */
michael@0: /*
michael@0:   bsdiff.c -- Binary patch generator.
michael@0: 
michael@0:   Copyright 2003 Colin Percival
michael@0: 
michael@0:   For the terms under which this work may be distributed, please see
michael@0:   the adjoining file "LICENSE".
michael@0: 
michael@0:   ChangeLog:
michael@0:   2005-05-05 - Use the modified header struct from bspatch.h; use 32-bit
michael@0:                values throughout.
michael@0:                  --Benjamin Smedberg <benjamin@smedbergs.us>
michael@0:   2005-05-18 - Use the same CRC algorithm as bzip2, and leverage the CRC table
michael@0:                provided by libbz2.
michael@0:                  --Darin Fisher <darin@meer.net>
michael@0: */
michael@0: 
michael@0: #include "bspatch.h"
michael@0: 
michael@0: #include <stdlib.h>
michael@0: #include <stdio.h>
michael@0: #include <string.h>
michael@0: #include <fcntl.h>
michael@0: #include <stdarg.h>
michael@0: #ifdef XP_WIN
michael@0: #include <io.h>
michael@0: #include <winsock2.h>
michael@0: #else
michael@0: #include <unistd.h>
michael@0: #include <arpa/inet.h>
michael@0: #define _O_BINARY 0
michael@0: #endif
michael@0: 
michael@0: #undef MIN
michael@0: #define MIN(x,y) (((x)<(y)) ? (x) : (y))
michael@0: 
michael@0: /*---------------------------------------------------------------------------*/
michael@0: 
michael@0: /* This variable lives in libbz2.  It's declared in bzlib_private.h, so we just
michael@0:  * declare it here to avoid including that entire header file.
michael@0:  */
michael@0: extern unsigned int BZ2_crc32Table[256];
michael@0: 
michael@0: static unsigned int
michael@0: crc32(const unsigned char *buf, unsigned int len)
michael@0: {
michael@0: 	unsigned int crc = 0xffffffffL;
michael@0: 
michael@0: 	const unsigned char *end = buf + len;
michael@0: 	for (; buf != end; ++buf)
michael@0: 		crc = (crc << 8) ^ BZ2_crc32Table[(crc >> 24) ^ *buf];
michael@0: 
michael@0: 	crc = ~crc;
michael@0: 	return crc;
michael@0: }
michael@0: 
michael@0: /*---------------------------------------------------------------------------*/
michael@0: 
michael@0: static void
michael@0: reporterr(int e, const char *fmt, ...)
michael@0: {
michael@0: 	if (fmt) {
michael@0: 		va_list args;
michael@0: 		va_start(args, fmt);
michael@0: 		vfprintf(stderr, fmt, args);
michael@0: 		va_end(args);
michael@0: 	}
michael@0: 
michael@0: 	exit(e);
michael@0: }
michael@0: 
michael@0: static void
michael@0: split(int32_t *I,int32_t *V,int32_t start,int32_t len,int32_t h)
michael@0: {
michael@0: 	int32_t i,j,k,x,tmp,jj,kk;
michael@0: 
michael@0: 	if(len<16) {
michael@0: 		for(k=start;k<start+len;k+=j) {
michael@0: 			j=1;x=V[I[k]+h];
michael@0: 			for(i=1;k+i<start+len;i++) {
michael@0: 				if(V[I[k+i]+h]<x) {
michael@0: 					x=V[I[k+i]+h];
michael@0: 					j=0;
michael@0: 				};
michael@0: 				if(V[I[k+i]+h]==x) {
michael@0: 					tmp=I[k+j];I[k+j]=I[k+i];I[k+i]=tmp;
michael@0: 					j++;
michael@0: 				};
michael@0: 			};
michael@0: 			for(i=0;i<j;i++) V[I[k+i]]=k+j-1;
michael@0: 			if(j==1) I[k]=-1;
michael@0: 		};
michael@0: 		return;
michael@0: 	};
michael@0: 
michael@0: 	x=V[I[start+len/2]+h];
michael@0: 	jj=0;kk=0;
michael@0: 	for(i=start;i<start+len;i++) {
michael@0: 		if(V[I[i]+h]<x) jj++;
michael@0: 		if(V[I[i]+h]==x) kk++;
michael@0: 	};
michael@0: 	jj+=start;kk+=jj;
michael@0: 
michael@0: 	i=start;j=0;k=0;
michael@0: 	while(i<jj) {
michael@0: 		if(V[I[i]+h]<x) {
michael@0: 			i++;
michael@0: 		} else if(V[I[i]+h]==x) {
michael@0: 			tmp=I[i];I[i]=I[jj+j];I[jj+j]=tmp;
michael@0: 			j++;
michael@0: 		} else {
michael@0: 			tmp=I[i];I[i]=I[kk+k];I[kk+k]=tmp;
michael@0: 			k++;
michael@0: 		};
michael@0: 	};
michael@0: 
michael@0: 	while(jj+j<kk) {
michael@0: 		if(V[I[jj+j]+h]==x) {
michael@0: 			j++;
michael@0: 		} else {
michael@0: 			tmp=I[jj+j];I[jj+j]=I[kk+k];I[kk+k]=tmp;
michael@0: 			k++;
michael@0: 		};
michael@0: 	};
michael@0: 
michael@0: 	if(jj>start) split(I,V,start,jj-start,h);
michael@0: 
michael@0: 	for(i=0;i<kk-jj;i++) V[I[jj+i]]=kk-1;
michael@0: 	if(jj==kk-1) I[jj]=-1;
michael@0: 
michael@0: 	if(start+len>kk) split(I,V,kk,start+len-kk,h);
michael@0: }
michael@0: 
michael@0: static void
michael@0: qsufsort(int32_t *I,int32_t *V,unsigned char *old,int32_t oldsize)
michael@0: {
michael@0: 	int32_t buckets[256];
michael@0: 	int32_t i,h,len;
michael@0: 
michael@0: 	for(i=0;i<256;i++) buckets[i]=0;
michael@0: 	for(i=0;i<oldsize;i++) buckets[old[i]]++;
michael@0: 	for(i=1;i<256;i++) buckets[i]+=buckets[i-1];
michael@0: 	for(i=255;i>0;i--) buckets[i]=buckets[i-1];
michael@0: 	buckets[0]=0;
michael@0: 
michael@0: 	for(i=0;i<oldsize;i++) I[++buckets[old[i]]]=i;
michael@0: 	I[0]=oldsize;
michael@0: 	for(i=0;i<oldsize;i++) V[i]=buckets[old[i]];
michael@0: 	V[oldsize]=0;
michael@0: 	for(i=1;i<256;i++) if(buckets[i]==buckets[i-1]+1) I[buckets[i]]=-1;
michael@0: 	I[0]=-1;
michael@0: 
michael@0: 	for(h=1;I[0]!=-(oldsize+1);h+=h) {
michael@0: 		len=0;
michael@0: 		for(i=0;i<oldsize+1;) {
michael@0: 			if(I[i]<0) {
michael@0: 				len-=I[i];
michael@0: 				i-=I[i];
michael@0: 			} else {
michael@0: 				if(len) I[i-len]=-len;
michael@0: 				len=V[I[i]]+1-i;
michael@0: 				split(I,V,i,len,h);
michael@0: 				i+=len;
michael@0: 				len=0;
michael@0: 			};
michael@0: 		};
michael@0: 		if(len) I[i-len]=-len;
michael@0: 	};
michael@0: 
michael@0: 	for(i=0;i<oldsize+1;i++) I[V[i]]=i;
michael@0: }
michael@0: 
michael@0: static int32_t
michael@0: matchlen(unsigned char *old,int32_t oldsize,unsigned char *newbuf,int32_t newsize)
michael@0: {
michael@0: 	int32_t i;
michael@0: 
michael@0: 	for(i=0;(i<oldsize)&&(i<newsize);i++)
michael@0: 		if(old[i]!=newbuf[i]) break;
michael@0: 
michael@0: 	return i;
michael@0: }
michael@0: 
michael@0: static int32_t
michael@0: search(int32_t *I,unsigned char *old,int32_t oldsize,
michael@0:        unsigned char *newbuf,int32_t newsize,int32_t st,int32_t en,int32_t *pos)
michael@0: {
michael@0: 	int32_t x,y;
michael@0: 
michael@0: 	if(en-st<2) {
michael@0: 		x=matchlen(old+I[st],oldsize-I[st],newbuf,newsize);
michael@0: 		y=matchlen(old+I[en],oldsize-I[en],newbuf,newsize);
michael@0: 
michael@0: 		if(x>y) {
michael@0: 			*pos=I[st];
michael@0: 			return x;
michael@0: 		} else {
michael@0: 			*pos=I[en];
michael@0: 			return y;
michael@0: 		}
michael@0: 	};
michael@0: 
michael@0: 	x=st+(en-st)/2;
michael@0: 	if(memcmp(old+I[x],newbuf,MIN(oldsize-I[x],newsize))<0) {
michael@0: 		return search(I,old,oldsize,newbuf,newsize,x,en,pos);
michael@0: 	} else {
michael@0: 		return search(I,old,oldsize,newbuf,newsize,st,x,pos);
michael@0: 	};
michael@0: }
michael@0: 
michael@0: int main(int argc,char *argv[])
michael@0: {
michael@0: 	int fd;
michael@0: 	unsigned char *old,*newbuf;
michael@0: 	int32_t oldsize,newsize;
michael@0: 	int32_t *I,*V;
michael@0: 
michael@0: 	int32_t scan,pos,len;
michael@0: 	int32_t lastscan,lastpos,lastoffset;
michael@0: 	int32_t oldscore,scsc;
michael@0: 
michael@0: 	int32_t s,Sf,lenf,Sb,lenb;
michael@0: 	int32_t overlap,Ss,lens;
michael@0: 	int32_t i;
michael@0: 
michael@0: 	int32_t dblen,eblen;
michael@0: 	unsigned char *db,*eb;
michael@0: 
michael@0: 	unsigned int scrc;
michael@0: 
michael@0: 	MBSPatchHeader header = {
michael@0: 		{'M','B','D','I','F','F','1','0'},
michael@0: 		0, 0, 0, 0, 0, 0
michael@0: 	};
michael@0: 
michael@0: 	uint32_t numtriples;
michael@0: 
michael@0: 	if(argc!=4)
michael@0: 		reporterr(1,"usage: %s <oldfile> <newfile> <patchfile>\n",argv[0]);
michael@0: 
michael@0: 	/* Allocate oldsize+1 bytes instead of oldsize bytes to ensure
michael@0: 		that we never try to malloc(0) and get a NULL pointer */
michael@0: 	if(((fd=open(argv[1],O_RDONLY|_O_BINARY,0))<0) ||
michael@0: 		((oldsize=lseek(fd,0,SEEK_END))==-1) ||
michael@0: 		((old=(unsigned char*) malloc(oldsize+1))==NULL) ||
michael@0: 		(lseek(fd,0,SEEK_SET)!=0) ||
michael@0: 		(read(fd,old,oldsize)!=oldsize) ||
michael@0: 		(close(fd)==-1))
michael@0: 		reporterr(1,"%s\n",argv[1]);
michael@0: 
michael@0: 	scrc = crc32(old, oldsize);
michael@0: 
michael@0: 	if(((I=(int32_t*) malloc((oldsize+1)*sizeof(int32_t)))==NULL) ||
michael@0: 		((V=(int32_t*) malloc((oldsize+1)*sizeof(int32_t)))==NULL))
michael@0: 		reporterr(1,NULL);
michael@0: 
michael@0: 	qsufsort(I,V,old,oldsize);
michael@0: 
michael@0: 	free(V);
michael@0: 
michael@0: 	/* Allocate newsize+1 bytes instead of newsize bytes to ensure
michael@0: 		that we never try to malloc(0) and get a NULL pointer */
michael@0: 	if(((fd=open(argv[2],O_RDONLY|_O_BINARY,0))<0) ||
michael@0: 		((newsize=lseek(fd,0,SEEK_END))==-1) ||
michael@0: 		((newbuf=(unsigned char*) malloc(newsize+1))==NULL) ||
michael@0: 		(lseek(fd,0,SEEK_SET)!=0) ||
michael@0: 		(read(fd,newbuf,newsize)!=newsize) ||
michael@0: 		(close(fd)==-1)) reporterr(1,"%s\n",argv[2]);
michael@0: 
michael@0: 	if(((db=(unsigned char*) malloc(newsize+1))==NULL) ||
michael@0: 		((eb=(unsigned char*) malloc(newsize+1))==NULL))
michael@0: 		reporterr(1,NULL);
michael@0: 
michael@0: 	dblen=0;
michael@0: 	eblen=0;
michael@0: 
michael@0: 	if((fd=open(argv[3],O_CREAT|O_TRUNC|O_WRONLY|_O_BINARY,0666))<0)
michael@0: 		reporterr(1,"%s\n",argv[3]);
michael@0: 
michael@0: 	/* start writing here */
michael@0: 
michael@0: 	/* We don't know the lengths yet, so we will write the header again
michael@0: 		 at the end */
michael@0: 
michael@0: 	if(write(fd,&header,sizeof(MBSPatchHeader))!=sizeof(MBSPatchHeader))
michael@0: 		reporterr(1,"%s\n",argv[3]);
michael@0: 
michael@0: 	scan=0;len=0;
michael@0: 	lastscan=0;lastpos=0;lastoffset=0;
michael@0: 	numtriples = 0;
michael@0: 	while(scan<newsize) {
michael@0: 		oldscore=0;
michael@0: 
michael@0: 		for(scsc=scan+=len;scan<newsize;scan++) {
michael@0: 			len=search(I,old,oldsize,newbuf+scan,newsize-scan,
michael@0: 					0,oldsize,&pos);
michael@0: 
michael@0: 			for(;scsc<scan+len;scsc++)
michael@0: 			if((scsc+lastoffset<oldsize) &&
michael@0: 				(old[scsc+lastoffset] == newbuf[scsc]))
michael@0: 				oldscore++;
michael@0: 
michael@0: 			if(((len==oldscore) && (len!=0)) || 
michael@0: 				(len>oldscore+8)) break;
michael@0: 
michael@0: 			if((scan+lastoffset<oldsize) &&
michael@0: 				(old[scan+lastoffset] == newbuf[scan]))
michael@0: 				oldscore--;
michael@0: 		};
michael@0: 
michael@0: 		if((len!=oldscore) || (scan==newsize)) {
michael@0: 			MBSPatchTriple triple;
michael@0: 
michael@0: 			s=0;Sf=0;lenf=0;
michael@0: 			for(i=0;(lastscan+i<scan)&&(lastpos+i<oldsize);) {
michael@0: 				if(old[lastpos+i]==newbuf[lastscan+i]) s++;
michael@0: 				i++;
michael@0: 				if(s*2-i>Sf*2-lenf) { Sf=s; lenf=i; };
michael@0: 			};
michael@0: 
michael@0: 			lenb=0;
michael@0: 			if(scan<newsize) {
michael@0: 				s=0;Sb=0;
michael@0: 				for(i=1;(scan>=lastscan+i)&&(pos>=i);i++) {
michael@0: 					if(old[pos-i]==newbuf[scan-i]) s++;
michael@0: 					if(s*2-i>Sb*2-lenb) { Sb=s; lenb=i; };
michael@0: 				};
michael@0: 			};
michael@0: 
michael@0: 			if(lastscan+lenf>scan-lenb) {
michael@0: 				overlap=(lastscan+lenf)-(scan-lenb);
michael@0: 				s=0;Ss=0;lens=0;
michael@0: 				for(i=0;i<overlap;i++) {
michael@0: 					if(newbuf[lastscan+lenf-overlap+i]==
michael@0: 					   old[lastpos+lenf-overlap+i]) s++;
michael@0: 					if(newbuf[scan-lenb+i]==
michael@0: 					   old[pos-lenb+i]) s--;
michael@0: 					if(s>Ss) { Ss=s; lens=i+1; };
michael@0: 				};
michael@0: 
michael@0: 				lenf+=lens-overlap;
michael@0: 				lenb-=lens;
michael@0: 			};
michael@0: 
michael@0: 			for(i=0;i<lenf;i++)
michael@0: 				db[dblen+i]=newbuf[lastscan+i]-old[lastpos+i];
michael@0: 			for(i=0;i<(scan-lenb)-(lastscan+lenf);i++)
michael@0: 				eb[eblen+i]=newbuf[lastscan+lenf+i];
michael@0: 
michael@0: 			dblen+=lenf;
michael@0: 			eblen+=(scan-lenb)-(lastscan+lenf);
michael@0: 
michael@0: 			triple.x = htonl(lenf);
michael@0: 			triple.y = htonl((scan-lenb)-(lastscan+lenf));
michael@0: 			triple.z = htonl((pos-lenb)-(lastpos+lenf));
michael@0: 			if (write(fd,&triple,sizeof(triple)) != sizeof(triple))
michael@0: 				reporterr(1,NULL);
michael@0: 
michael@0: #ifdef DEBUG_bsmedberg
michael@0: 			printf("Writing a block:\n"
michael@0: 			       "	X: %u\n"
michael@0: 			       "	Y: %u\n"
michael@0: 			       "	Z: %i\n",
michael@0: 			       (uint32_t) lenf,
michael@0: 			       (uint32_t) ((scan-lenb)-(lastscan+lenf)),
michael@0: 			       (uint32_t) ((pos-lenb)-(lastpos+lenf)));
michael@0: #endif
michael@0: 
michael@0: 			++numtriples;
michael@0: 
michael@0: 			lastscan=scan-lenb;
michael@0: 			lastpos=pos-lenb;
michael@0: 			lastoffset=pos-scan;
michael@0: 		};
michael@0: 	};
michael@0: 
michael@0: 	if(write(fd,db,dblen)!=dblen)
michael@0: 		reporterr(1,NULL);
michael@0: 
michael@0: 	if(write(fd,eb,eblen)!=eblen)
michael@0: 		reporterr(1,NULL);
michael@0: 
michael@0: 	header.slen	= htonl(oldsize);
michael@0: 	header.scrc32	= htonl(scrc);
michael@0: 	header.dlen	= htonl(newsize);
michael@0: 	header.cblen	= htonl(numtriples * sizeof(MBSPatchTriple));
michael@0: 	header.difflen	= htonl(dblen);
michael@0: 	header.extralen = htonl(eblen);
michael@0: 
michael@0: 	if (lseek(fd,0,SEEK_SET) == -1 ||
michael@0: 	    write(fd,&header,sizeof(header)) != sizeof(header) ||
michael@0: 	    close(fd) == -1)
michael@0: 		reporterr(1,NULL);
michael@0: 
michael@0: 	free(db);
michael@0: 	free(eb);
michael@0: 	free(I);
michael@0: 	free(old);
michael@0: 	free(newbuf);
michael@0: 
michael@0: 	return 0;
michael@0: }
michael@0: