BSD 4_2 release

[unix-history] / usr / src / games / trek / dumpgame.c

#ifndef lint
static char sccsid[] = "@(#)dumpgame.c  4.2     (Berkeley)      5/27/83";
#endif not lint

# include       "trek.h"

/***  THIS CONSTANT MUST CHANGE AS THE DATA SPACES CHANGE ***/
# define        VERSION         2

struct dump
{
       char    *area;
       int     count;
};


struct dump     Dump_template[] =
{
       (char *)&Ship,          sizeof (Ship),
       (char *)&Now,           sizeof (Now),
       (char *)&Param,         sizeof (Param),
       (char *)&Etc,           sizeof (Etc),
       (char *)&Game,          sizeof (Game),
       (char *)Sect,           sizeof (Sect),
       (char *)Quad,           sizeof (Quad),
       (char *)&Move,          sizeof (Move),
       (char *)Event,          sizeof (Event),
       0
};

/*
**  DUMP GAME
**
**      This routine dumps the game onto the file "trek.dump".  The
**      first two bytes of the file are a version number, which
**      reflects whether this image may be used.  Obviously, it must
**      change as the size, content, or order of the data structures
**      output change.
*/

dumpgame()
{
       int                     version;
       register int            fd;
       register struct dump    *d;
       register int            i;

       if ((fd = creat("trek.dump", 0644)) < 0)
               return (printf("cannot dump\n"));
       version = VERSION;
       write(fd, &version, sizeof version);

       /* output the main data areas */
       for (d = Dump_template; d->area; d++)
       {
               write(fd, &d->area, sizeof d->area);
               i = d->count;
               write(fd, d->area, i);
       }

       close(fd);
}


/*
**  RESTORE GAME
**
**      The game is restored from the file "trek.dump".  In order for
**      this to succeed, the file must exist and be readable, must
**      have the correct version number, and must have all the appro-
**      priate data areas.
**
**      Return value is zero for success, one for failure.
*/

restartgame()
{
       register int    fd;
       int             version;

       if ((fd = open("trek.dump", 0)) < 0 ||
           read(fd, &version, sizeof version) != sizeof version ||
           version != VERSION ||
           readdump(fd))
       {
               printf("cannot restart\n");
               close(fd);
               return (1);
       }

       close(fd);
       return (0);
}


/*
**  READ DUMP
**
**      This is the business end of restartgame().  It reads in the
**      areas.
**
**      Returns zero for success, one for failure.
*/

readdump(fd1)
int     fd1;
{
       register int            fd;
       register struct dump    *d;
       register int            i;
       int                     junk;

       fd = fd1;

       for (d = Dump_template; d->area; d++)
       {
               if (read(fd, &junk, sizeof junk) != (sizeof junk))
                       return (1);
               if ((char *)junk != d->area)
                       return (1);
               i = d->count;
               if (read(fd, d->area, i) != i)
                       return (1);
       }

       /* make quite certain we are at EOF */
       return (read(fd, &junk, 1));
}