text: /*-
   * Copyright 2003-2005 Colin Percival
   * All rights reserved
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted providing that the following conditions 
   * are met:
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   *
   * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
   * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
   * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
   * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
   * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
   * IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   */
  
  #if 0
  __FBSDID("$FreeBSD: src/usr.bin/bsdiff/bspatch/bspatch.c,v 1.1 2005/08/06 01:59:06 cperciva Exp $");
  #endif
  
  #include <bspatch.h>
  #include <bzlib.h>
  #include <stdlib.h>
  #include <stdio.h>
  #include <string.h>
  #include <err.h>
  #include <unistd.h>
  #include <fcntl.h>
  
  /* Compatibility layer for reading either the old BSDIFF40 or the new BSDIFN40
     patch formats: */
  
  typedef void* stream_t;
  
  typedef struct
  {
  	stream_t (*open)(FILE*);
  	void (*close)(stream_t);
  	int (*read)(stream_t, void*, int);
  } io_funcs_t;
  
  static stream_t BSDIFF40_open(FILE *f)
  {
  	int bzerr;
  	BZFILE *s;
  	if ((s = BZ2_bzReadOpen(&bzerr, f, 0, 0, NULL, 0)) == NULL)
  		errx(1, "BZ2_bzReadOpen, bz2err = %d", bzerr);
  	return s;
  }
  
  static void BSDIFF40_close(stream_t s)
  {
  	int bzerr;
  	BZ2_bzReadClose(&bzerr, (BZFILE*)s);
  }
  
  static int BSDIFF40_read(stream_t s, void *buf, int len)
  {
  	int bzerr, lenread;
  	lenread = BZ2_bzRead(&bzerr, (BZFILE*)s, buf, len);
  	if (bzerr != BZ_OK && bzerr != BZ_STREAM_END)
  		errx(1, "Corrupt patch\n");
  	return lenread;
  }
  
  static io_funcs_t BSDIFF40_funcs = {
  	BSDIFF40_open,
  	BSDIFF40_close,
  	BSDIFF40_read
  };
  
  
  static stream_t BSDIFN40_open(FILE *f)
  {
  	return f;
  }
  
  static void BSDIFN40_close(stream_t s)
  {
  }
  
  static int BSDIFN40_read(stream_t s, void *buf, int len)
  {
  	return fread(buf, 1, len, (FILE*)s);
  }
  
  static io_funcs_t BSDIFN40_funcs = {
  	BSDIFN40_open,
  	BSDIFN40_close,
  	BSDIFN40_read
  };
  
  
  #ifndef u_char
  typedef unsigned char u_char;
  #endif
  
  static 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 bspatch(int argc,char * argv[])
  {
  	FILE * f, * cpf, * dpf, * epf;
  	stream_t cstream, dstream, estream;
  	int fd;
  	ssize_t oldsize,newsize;
  	ssize_t bzctrllen,bzdatalen;
  	u_char header[32],buf[8];
  	u_char *old, *new;
  	off_t oldpos,newpos;
  	off_t ctrl[3];
  	off_t lenread;
  	off_t i;
  	io_funcs_t * io;
  
  	if(argc!=4) errx(1,"usage: %s oldfile newfile patchfile\n",argv[0]);
  
  	/* Open patch file */
  	if ((f = fopen(argv[3], "r")) == NULL)
  		err(1, "fopen(%s)", argv[3]);
  
  	/*
  	File format:
  		0	8	"BSDIFF40" (bzip2) or "BSDIFN40" (raw)
  		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".
  	*/
  
  	/* Read header */
  	if (fread(header, 1, 32, f) < 32) {
  		if (feof(f))
  			errx(1, "Corrupt patch\n");
  		err(1, "fread(%s)", argv[3]);
  	}
  
  	/* Check for appropriate magic */
  	if (memcmp(header, "BSDIFF40", 8) == 0)
  		io = &BSDIFF40_funcs;
  	else if (memcmp(header, "BSDIFN40", 8) == 0)
  		io = &BSDIFN40_funcs;
  	else
  		errx(1, "Corrupt patch\n");
  
  	/* Read lengths from header */
  	bzctrllen=offtin(header+8);
  	bzdatalen=offtin(header+16);
  	newsize=offtin(header+24);
  	if((bzctrllen<0) || (bzdatalen<0) || (newsize<0))
  		errx(1,"Corrupt patch\n");
  
  	/* Close patch file and re-open it via libbzip2 at the right places */
  	if (fclose(f))
  		err(1, "fclose(%s)", argv[3]);
  	if ((cpf = fopen(argv[3], "r")) == NULL)
  		err(1, "fopen(%s)", argv[3]);
  	if (fseeko(cpf, 32, SEEK_SET))
  		err(1, "fseeko(%s, %lld)", argv[3],
  		    (long long)32);
  	cstream = io->open(cpf);
  	if ((dpf = fopen(argv[3], "r")) == NULL)
  		err(1, "fopen(%s)", argv[3]);
  	if (fseeko(dpf, 32 + bzctrllen, SEEK_SET))
  		err(1, "fseeko(%s, %lld)", argv[3],
  		    (long long)(32 + bzctrllen));
  	dstream = io->open(dpf);
  	if ((epf = fopen(argv[3], "r")) == NULL)
  		err(1, "fopen(%s)", argv[3]);
  	if (fseeko(epf, 32 + bzctrllen + bzdatalen, SEEK_SET))
  		err(1, "fseeko(%s, %lld)", argv[3],
  		    (long long)(32 + bzctrllen + bzdatalen));
  	estream = io->open(epf);
  
  	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) {
  		/* Read control data */
  		for(i=0;i<=2;i++) {
  			lenread = io->read(cstream, buf, 8);
  			if (lenread < 8)
  				errx(1, "Corrupt patch\n");
  			ctrl[i]=offtin(buf);
  		};
  
  		/* Sanity-check */
  		if(newpos+ctrl[0]>newsize)
  			errx(1,"Corrupt patch\n");
  
  		/* Read diff string */
  		lenread = io->read(dstream, new + newpos, ctrl[0]);
  		if (lenread < ctrl[0])
  			errx(1, "Corrupt patch\n");
  
  		/* Add old data to diff string */
  		for(i=0;i<ctrl[0];i++)
  			if((oldpos+i>=0) && (oldpos+i<oldsize))
  				new[newpos+i]+=old[oldpos+i];
  
  		/* Adjust pointers */
  		newpos+=ctrl[0];
  		oldpos+=ctrl[0];
  
  		/* Sanity-check */
  		if(newpos+ctrl[1]>newsize)
  			errx(1,"Corrupt patch\n");
  
  		/* Read extra string */
  		lenread = io->read(estream, new + newpos, ctrl[1]);
  		if (lenread < ctrl[1])
  			errx(1, "Corrupt patch\n");
  
  		/* Adjust pointers */
  		newpos+=ctrl[1];
  		oldpos+=ctrl[2];
  	};
  
  	/* Clean up the bzip2 reads */
  	io->close(cstream);
  	io->close(dstream);
  	io->close(estream);
  	if (fclose(cpf) || fclose(dpf) || fclose(epf))
  		err(1, "fclose(%s)", argv[3]);
  
  	/* Write the new file */
  	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;
  }
  