The Tor Browser: other-licenses/bsdiff/bsdiff.c@b8a032363ba2 (annotated)

other-licenses/bsdiff/bsdiff.c@b8a032363ba2 (annotated)

other-licenses/bsdiff/bsdiff.c

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 /* 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:
 -05-05 - Use the modified header struct from bspatch.h; use 32-bit
                values throughout.
                  --Benjamin Smedberg <benjamin@smedbergs.us>
 -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>
 #else
 #include <unistd.h>
 #include <arpa/inet.h>
 #define _O_BINARY 0
 #endif
 #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
 	};
 	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,
 ,oldsize,&pos);
 			for(;scsc<scan+len;scsc++)
 			if((scsc+lastoffset<oldsize) &&
 				(old[scsc+lastoffset] == newbuf[scsc]))
 				oldscore++;
 			if(((len==oldscore) && (len!=0)) ||
 				(len>oldscore+8)) 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*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[pos-i]==newbuf[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(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;
 }

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other-licenses/bsdiff/bsdiff.c@b8a032363ba2 (annotated)

other-licenses/bsdiff/bsdiff.c