/* utility to extract the .SHR installer data files of early ID software

   shareware games

    Copyright (C) 2007 Hans de Goede  <j.w.r.degoede@hhs.nl>

    This program is free software; you can redistribute it and/or modify

    it under the terms of the GNU General Public License as published by

    the Free Software Foundation; either version 2 of the License, or   

    (at your option) any later version.

    This program is distributed in the hope that it will be useful,

    but WITHOUT ANY WARRANTY; without even the implied warranty of 

    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the  

    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License

    along with this program; if not, write to the Free Software

    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA

*/

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <ctype.h>

#include <libdynamite.h>

struct cookie_s {

  char *in_buffer;

  int in_buffer_remaining;

  int in_buffer_index;

  int in_buffer_size;

  FILE* out_file;

};   

size_t reader(void* buffer, size_t size, void* cookie)

{

  struct cookie_s *c = cookie;

  if (size > c->in_buffer_remaining)

    size = c->in_buffer_remaining;

  memcpy (buffer, c->in_buffer + c->in_buffer_index, size);

  c->in_buffer_index += size;

  c->in_buffer_remaining -= size;

  return size;

}

size_t writer(void* buffer, size_t size, void* cookie)

{

  struct cookie_s *c = cookie;

  return fwrite(buffer, 1, size, c->out_file);

}

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

{

  struct cookie_s cookie;

  FILE *in_file;

  char filename[16];

  unsigned char buf[4];

  int i, compressed_size;

  if (argc != 2) {

    fprintf(stderr, "%s: Usage: %s <filename.CHR> %d\n", argv[0], argv[0], argc);

    return 1;

  }

  in_file = fopen(argv[1], "r");

  if (!in_file) {

    fprintf(stderr, "error opening: %s", argv[1]);

    perror(NULL);

    return 1;

  } 

  /* skip first 0x3A bytes header */

  if (fseek(in_file, 0x3A, SEEK_CUR)) {

    perror("error skipping initial file header");

    return 1;

  }

  cookie.in_buffer = malloc(65536);

  if (!cookie.in_buffer) {

    fprintf(stderr, "Error: out of memory\n");

    return 1;

  }

  cookie.in_buffer_size = 65536;

  while (1)

  {

    /* get the name of the file */

    if (fread(filename, 1, sizeof(filename), in_file) != sizeof(filename)) {

      if (feof(in_file)) {

        free(cookie.in_buffer);

        fclose(in_file);

        return 0; /* done */

      }

      perror("error getting output filename from file");

      return 1;

    }

    /* verify the filename and convert to lower case */

    for (i = 0 ; i < sizeof(filename); i++) {

      if (filename[i] == 0)

        break; /* done */

      if (!isprint(filename[i])) {

        fprintf(stderr, "error invalid output filename\n");

        return 1;

      }

      filename[i] = tolower(filename[i]);

    }

    if (i == sizeof(filename)) {

      fprintf(stderr, "error too long output filename\n");

      return 1;

    }

    /* seek to compressed size */

    if (fseek(in_file, 0x88 - sizeof(filename), SEEK_CUR)) {

      perror("error skipping file header before file size");

      return 1;

    }

    if (fread(buf, 1, 4, in_file) != 4) {

      perror("error reading file size");

      return 1;

    }

    compressed_size = (buf[3] << 24) | (buf[2] << 16) | (buf[1] << 8) | buf[0];

    if (compressed_size > cookie.in_buffer_size) {

      cookie.in_buffer = realloc(cookie.in_buffer, compressed_size);

      if (!cookie.in_buffer) {

        fprintf(stderr, "Error: out of memory\n");

        return 1;

      }

      cookie.in_buffer_size = compressed_size;

    }

    /* seek to begin of compressed data */

    if (fseek(in_file, 0x1C, SEEK_CUR)) {

      perror("error skipping file header before file size");

      return 1;

    }

    /* read compressed data */

    if (fread(cookie.in_buffer, 1, compressed_size, in_file) !=

          compressed_size) {

      perror("error reading compressed data");

      return 1;

    }

    cookie.in_buffer_index = 0;

    cookie.in_buffer_remaining = compressed_size;

    cookie.out_file = fopen(filename, "w");

    if (!cookie.out_file) {

      fprintf(stderr, "Error creating: %s for writing", filename);

      perror(NULL);

      return 1;

    }

    printf("decompressing: %s, compressed size: %d\n", filename,

            compressed_size);

    if ((i = dynamite_explode(reader, writer, &cookie))) {

      fprintf(stderr, "Error: %d while decompressing\n", i);

      return i;

    }

    fclose(cookie.out_file);

  }

  /* never reached */

  return 0;

}