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/*
.c -- Binary patcher
Copyright 2003,2004 Colin Percival
For the terms under which this work may be distributed, please see
the adjoining file "LICENSE".
*/
#ifndef BZIP2
#define BZIP2 "/usr/bin/bzip2"
#endif
#include <stdlib.h>
#include <stdio.h>
#include <err.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/wait.h>
ssize_t loopread(int d,void *buf,size_t nbytes)
{
ssize_t ptr,lenread;
for(ptr=0;ptr<nbytes;ptr+=lenread) {
lenread=read(d,buf+ptr,nbytes-ptr);
if(lenread==0) return ptr;
if(lenread==-1) return -1;
};
return ptr;
}
int bz2read(int fd,off_t offset,off_t len,char * fname,pid_t * pids)
{
int p0[2],p1[2];
u_char * data;
if((pipe(p0)==-1) || (pipe(p1)==-1)) err(1,NULL);
if((pids[0]=fork())==-1) err(1,NULL);
if(pids[0]==0) {
if(close(0) || close(1) || close(p0[0]) ||
close(p1[0]) || close(p1[1])) err(1,NULL);
if((data=malloc(len+1))==NULL) err(1,NULL);
if((pread(fd,data,len,offset)!=len) || close(fd))
err(1,"%s",fname);
if((write(p0[1],data,len)!=len) || close(p0[1]))
err(1,NULL);
free(data);
_exit(0);
};
if((pids[1]=fork())==-1) err(1,NULL);
if(pids[1]==0) {
if(close(0) || close(1) || close(p0[1]) ||
close(p1[0])) err(1,NULL);
if((dup2(p0[0],0)==-1) || close(p0[0])) err(1,NULL);
if((dup2(p1[1],1)==-1) || close(p1[1])) err(1,NULL);
if(close(fd)==-1) err(1,"%s",fname);
execl(BZIP2,BZIP2,"-dc",NULL);
err(1,"%s",BZIP2);
};
if(close(p0[0]) || close(p0[1]) || close(p1[1])) err(1,NULL);
return p1[0];
}
off_t offtin(u_char *buf)
{
off_t y;
y=buf[7]&0x7F;
y=y*256;y+=buf[6];
y=y*256;y+=buf[5];
y=y*256;y+=buf[4];
y=y*256;y+=buf[3];
y=y*256;y+=buf[2];
y=y*256;y+=buf[1];
y=y*256;y+=buf[0];
if(buf[7]&0x80) y=-y;
return y;
}
int main(int argc,char * argv[])
{
int fd,ctrlpipe,diffpipe,extrapipe;
pid_t pids[6];
ssize_t patchsize,oldsize,newsize;
ssize_t bzctrllen,bzdatalen;
u_char header[32],buf[8];
int version=0;
u_char *old, *new;
off_t oldpos,newpos;
off_t ctrl[3];
off_t lenread;
off_t i;
if(argc!=4) errx(1,"usage: %s oldfile newfile patchfile\n",argv[0]);
if(((fd=open(argv[3],O_RDONLY,0))<0) ||
((patchsize=lseek(fd,0,SEEK_END))==-1) ||
(lseek(fd,0,SEEK_SET)!=0)) err(1,"%s",argv[3]);
if(patchsize<32) errx(1,"Corrupt patch\n");
/*
Ok, this is going to be messy. There are two different patch
formats which we need to support.
The old format (pre-4.0) is:
0 8 "QSUFDIFF" or "BSDIFF30"
8 8 X
16 8 Y
24 8 sizeof(newfile)
32 X bzip2(control block)
32+X Y bzip2(data block)
with control block a set of pairs (x,y) meaning "seek forward
in oldfile by y bytes, and add the next x bytes to x bytes from
the data block".
The new format (4.0) is:
0 8 "BSDIFF40"
8 8 X
16 8 Y
24 8 sizeof(newfile)
32 X bzip2(control block)
32+X Y bzip2(diff block)
32+X+Y ??? bzip2(extra block)
with control block a set of triples (x,y,z) meaning "add x bytes
from oldfile to x bytes from the diff block; copy y bytes from the
extra block; seek forwards in oldfile by z bytes".
*/
if(read(fd,header,32)!=32) err(1,"%s",argv[3]);
if(memcmp(header,"QSUFDIFF",8)==0) version=1;
if(memcmp(header,"BSDIFF30",8)==0) version=1;
if(memcmp(header,"BSDIFF40",8)==0) version=2;
if(!version) errx(1,"Corrupt patch\n");
bzctrllen=offtin(header+8);
bzdatalen=offtin(header+16);
newsize=offtin(header+24);
if((bzctrllen<0) || (bzdatalen<0) || (newsize<0) ||
((version==1) && (32+bzctrllen+bzdatalen!=patchsize)))
errx(1,"Corrupt patch\n");
ctrlpipe=bz2read(fd,32,bzctrllen,argv[3],pids);
diffpipe=bz2read(fd,32+bzctrllen,bzdatalen,argv[3],pids+2);
if(version==2) {
extrapipe=bz2read(fd,32+bzctrllen+bzdatalen,
patchsize-(32+bzctrllen+bzdatalen),argv[3],pids+4);
};
if(close(fd)==-1) err(1,"%s",argv[3]);
if(((fd=open(argv[1],O_RDONLY,0))<0) ||
((oldsize=lseek(fd,0,SEEK_END))==-1) ||
((old=malloc(oldsize+1))==NULL) ||
(lseek(fd,0,SEEK_SET)!=0) ||
(read(fd,old,oldsize)!=oldsize) ||
(close(fd)==-1)) err(1,"%s",argv[1]);
if((new=malloc(newsize+1))==NULL) err(1,NULL);
oldpos=0;newpos=0;
while(newpos<newsize) {
for(i=0;i<=version;i++) {
if((lenread=loopread(ctrlpipe,buf,8))<0) err(1,NULL);
if(lenread<8) errx(1,"Corrupt patch\n");
ctrl[i]=offtin(buf);
};
if(version==1) oldpos+=ctrl[1];
if(newpos+ctrl[0]>newsize) errx(1,"Corrupt patch\n");
if((lenread=loopread(diffpipe,new+newpos,ctrl[0]))<0)
err(1,NULL);
if(lenread!=ctrl[0]) errx(1,"Corrupt patch\n");
for(i=0;i<ctrl[0];i++)
if((oldpos+i>=0) && (oldpos+i<oldsize))
new[newpos+i]+=old[oldpos+i];
newpos+=ctrl[0];
oldpos+=ctrl[0];
if(version==2) {
if(newpos+ctrl[1]>newsize) errx(1,"Corrupt patch\n");
if((lenread=loopread(extrapipe,new+newpos,ctrl[1]))<0)
err(1,NULL);
if(lenread!=ctrl[1]) errx(1,"Corrupt patch\n");
newpos+=ctrl[1];
oldpos+=ctrl[2];
};
};
if(loopread(ctrlpipe,buf,1)!=0) errx(1,"Corrupt patch\n");
if(loopread(diffpipe,buf,1)!=0) errx(1,"Corrupt patch\n");
if(version==2)
if(loopread(extrapipe,buf,1)!=0) errx(1,"Corrupt patch\n");
if(close(ctrlpipe) || close(diffpipe) ||
((version==2) && close(extrapipe)))
err(1,NULL);
for(i=0;i<(version+1)*2;i++) waitpid(pids[i],NULL,0);
if(((fd=open(argv[2],O_CREAT|O_TRUNC|O_WRONLY,0666))<0) ||
(write(fd,new,newsize)!=newsize) || (close(fd)==-1))
err(1,"%s",argv[2]);
free(new);
free(old);
return 0;
}
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