/***********************************************************************
* *
* This software is part of the ast package *
* Copyright (c) 1989-2011 AT&T Intellectual Property *
* and is licensed under the *
* Eclipse Public License, Version 1.0 *
* by AT&T Intellectual Property *
* *
* A copy of the License is available at *
* http://www.eclipse.org/org/documents/epl-v10.html *
* (with md5 checksum b35adb5213ca9657e911e9befb180842) *
* *
* Information and Software Systems Research *
* AT&T Research *
* Florham Park NJ *
* *
* Phong Vo <kpv@research.att.com> *
* *
***********************************************************************/
#pragma prototyped
#include "update.h"
/*
** Reconstruct a target file from a source file and a delta file.
** The delta file contain block move instructions computed by delta().
**
** Written by Kiem-Phong Vo, 5/20/88
*/
/* buffers for delta and target files */
static unsigned char *Ddata, *Dnext, *Dend,
*Tdata, *Tnext, *Tend;
static int Dfd, Tfd;
#define delinit(buf,size,fd) (Ddata=Dnext=Dend=buf, Dfd=fd)
#define tarinit(buf,size,fd) (Tdata=Tnext=buf, Tend=buf+size, Tfd=fd)
#define tarflush() (write(Tfd,(char*)Tdata,Tnext-Tdata) >= 0 ? (Tnext=Tdata,0) : -1)
/* read a byte from delta file */
static int delgetc(void)
{
if(Dnext >= Dend)
{
register int n;
if((n = read(Dfd,(char*)Ddata,BUFSIZE)) <= 0)
return -1;
Dnext = Ddata, Dend = Ddata+n;
}
return (int)(*Dnext++);
}
/* read a long value from delta file */
static long delgetl(register int n)
{
register long lv;
lv = 0;
for(; n > 0; --n)
{
register int v;
if((v = delgetc()) < 0)
return -1;
lv = lv*256 + v;
}
return lv;
}
/* transfer a number of bytes from a file to the target file */
static int filetransfer(int fd, long n)
{
while(n > 0)
{
register int r;
if(Tnext >= Tend)
if(tarflush() < 0)
return -1;
r = n > (Tend-Tnext) ? (Tend-Tnext) : n;
if(read(fd,(char*)Tnext,r) != r)
return -1;
Tnext += r;
n -= r;
}
return 0;
}
/* transfer a number of bytes from a memory area to the target file */
static int memtransfer(unsigned char* addr, register long n)
{
while(n > 0)
{
register int r;
if(Tnext >= Tend)
if(tarflush() < 0)
return -1;
r = n > (Tend-Tnext) ? (Tend-Tnext) : n;
memcpy(Tnext,addr,r);
Tnext += r;
addr += r;
n -= r;
}
return 0;
}
/* transfer a number of bytes from delta to target */
static int deltransfer(long n)
{
register int d;
/* transfer what's already in core */
if((d = Dend-Dnext) > 0)
{
register int w = n <= d ? n : d;
if(w > (Tend-Tnext))
if(tarflush() < 0)
return -1;
/* copy from the delta buffer */
memcpy(Tnext,Dnext,w);
Dnext += w;
Tnext += w;
n -= w;
}
return n > 0 ? filetransfer(Dfd,n) : 0;
}
int
update(int srcfd, long offset, int delfd, int tarfd)
{
register int i;
register long n_src, n_tar;
unsigned char delbuf[BUFSIZE], tarbuf[BUFSIZE];
unsigned char *src, *tar;
/* start buffering system for delta file */
delinit(delbuf,BUFSIZE,delfd);
/* read the file sizes */
if((i = delgetc()) < 0 || (i&DELTA_TYPE) != DELTA_TYPE)
return -1;
if((n_src = delgetl((i>>3)&07)) < 0 || (n_tar = delgetl(i&07)) < 0)
return -1;
/* make data area for target file */
if(tar = (unsigned char*)malloc(n_tar)) /* assignment = */
tarinit(tar,n_tar,tarfd);
else tarinit(tarbuf,BUFSIZE,tarfd);
/* read in source file if possible to avoid lseek */
if(src = (unsigned char*)malloc(n_src)) /* assignment = */
{
lseek(srcfd,offset,0);
if(read(srcfd,(char*)src,n_src) != n_src)
return -1;
}
while((i = delgetc()) >= 0)
{
register long size, addr;
if((size = delgetl((i>>3)&07)) < 0)
return -1;
switch(i&DELTA_TYPE)
{
default :
return -1;
case DELTA_TYPE :
/* sync delta file pointer */
if((addr = Dend-Dnext) > 0)
lseek(Dfd,-addr,1);
/* flush output buffer */
if(tarflush() < 0)
return -1;
/* free space used */
if(src)
free(src);
if(tar)
free(tar);
return 0;
case DELTA_MOVE :
if((addr = delgetl(i&07)) < 0)
return -1;
if(src)
{
if(memtransfer(src+addr,size) < 0)
return -1;
}
else
{
if(lseek(srcfd,offset+addr,0) < 0)
return -1;
if(filetransfer(srcfd,size) < 0)
return -1;
}
break;
case DELTA_ADD :
if(deltransfer(size) < 0)
return -1;
break;
}
}
/* should never get here */
return -1;
}