/*-

 * Copyright 2003-2005 Colin Percival

 * Copyright 2012 Matthew Endsley

 * 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.

 */

#include <limits.h>

#include "bspatch.h"

static int64_t offtin(uint8_t *buf)

{

  int64_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(const uint8_t* old, int64_t oldsize, uint8_t* new, int64_t newsize, struct bspatch_stream* stream)

{

  uint8_t buf[8];

  int64_t oldpos,newpos;

  int64_t ctrl[3];

  int64_t i;

  oldpos=0;newpos=0;

  while(newpos<newsize) {

    /* Read control data */

    for(i=0;i<=2;i++) {

      if (stream->read(stream, buf, 8))

        return -1;

      ctrl[i]=offtin(buf);

    };

    /* Sanity-check */

    if (ctrl[0]<0 || ctrl[0]>INT_MAX ||

      ctrl[1]<0 || ctrl[1]>INT_MAX ||

      newpos+ctrl[0]>newsize)

      return -1;

    /* Read diff string */

    if (stream->read(stream, new + newpos, ctrl[0]))

      return -1;

    /* 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)

      return -1;

    /* Read extra string */

    if (stream->read(stream, new + newpos, ctrl[1]))

      return -1;

    /* Adjust pointers */

    newpos+=ctrl[1];

    oldpos+=ctrl[2];

  };

  return 0;

}

#if defined(BSPATCH_EXECUTABLE)

#include <bzlib.h>

#include <stdlib.h>

#include <stdint.h>

#include <stdio.h>

#include <string.h>

#include <err.h>

#include <sys/types.h>

#include <sys/stat.h>

#include <unistd.h>

#include <fcntl.h>

static int bz2_read(const struct bspatch_stream* stream, void* buffer, int length)

{

  int n;

  int bz2err;

  BZFILE* bz2;

  bz2 = (BZFILE*)stream->opaque;

  n = BZ2_bzRead(&bz2err, bz2, buffer, length);

  if (n != length)

    return -1;

  return 0;

}

int main(int argc,char * argv[])

{

  FILE * f;

  int fd;

  int bz2err;

  uint8_t header[24];

  uint8_t *old, *new;

  int64_t oldsize, newsize;

  BZFILE* bz2;

  struct bspatch_stream stream;

  struct stat sb;

  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]);

  /* Read header */

  if (fread(header, 1, 24, f) != 24) {

    if (feof(f))

      errx(1, "Corrupt patch\n");

    err(1, "fread(%s)", argv[3]);

  }

  /* Check for appropriate magic */

  if (memcmp(header, "ENDSLEY/BSDIFF43", 16) != 0)

    errx(1, "Corrupt patch\n");

  /* Read lengths from header */

  newsize=offtin(header+16);

  if(newsize<0)

    errx(1,"Corrupt patch\n");

  /* Close patch file and re-open it via libbzip2 at the right places */

  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) ||

    (fstat(fd, &sb)) ||

    (close(fd)==-1)) err(1,"%s",argv[1]);

  if((new=malloc(newsize+1))==NULL) err(1,NULL);

  if (NULL == (bz2 = BZ2_bzReadOpen(&bz2err, f, 0, 0, NULL, 0)))

    errx(1, "BZ2_bzReadOpen, bz2err=%d", bz2err);

  stream.read = bz2_read;

  stream.opaque = bz2;

  if (bspatch(old, oldsize, new, newsize, &stream))

    errx(1, "bspatch");

  /* Clean up the bzip2 reads */

  BZ2_bzReadClose(&bz2err, bz2);

  fclose(f);

  /* Write the new file */

  if(((fd=open(argv[2],O_CREAT|O_TRUNC|O_WRONLY,sb.st_mode))<0) ||

    (write(fd,new,newsize)!=newsize) || (close(fd)==-1))

    err(1,"%s",argv[2]);

  free(new);

  free(old);

  return 0;

}

#endif