/*
 * As its sole author, I explicitly place this program in the public domain.
 * It may be used by anyone in any way for any purpose, though I would
 * appreciate credit where it's due.
 *		der Mouse, mouse@rodents.montreal.qc.ca, 1998-08-05
 */

#include <stdio.h>
#include <errno.h>
#include <ctype.h>
#include <stdlib.h>
#include <unistd.h>
#include <strings.h>

extern const char *__progname;

static int fd;
static int whence = SEEK_SET;
static off_t offset;
static int have = 0;
#define HAVE_FD     1
#define HAVE_OFFSET 2
static int qflag = 0;

static void handleargs(int ac, char **av)
{
 int skip;
 int errs;
 char *ep;

 skip = 0;
 errs = 0;
 for (ac--,av++;ac;ac--,av++)
  { if (skip > 0)
     { skip --;
       continue;
     }
    if ((**av != '-') || isdigit((unsigned char)av[0][1]))
     { if (! (have & HAVE_FD))
	{ fd = strtol(*av,&ep,0);
	  if ((fd < 0) || *ep || (ep == *av))
	   { if (! qflag) fprintf(stderr,"%s: invalid file descriptor argument `%s'\n",__progname,*av);
	     errs ++;
	   }
	  else
	   { have |= HAVE_FD;
	   }
	}
       else if (! (have & HAVE_OFFSET))
	{ offset = strtoq(*av,&ep,0);
	  if (*ep || (ep == *av))
	   { if (! qflag) fprintf(stderr,"%s: invalid offset argument `%s'\n",__progname,*av);
	     errs ++;
	   }
	  else
	   { have |= HAVE_OFFSET;
	   }
	}
       else
	{ if (! qflag) fprintf(stderr,"%s: extra argument `%s'\n",__progname,*av);
	  errs ++;
	}
       continue;
     }
#if 0
    if (0)
     {
needarg:;
       if (! qflag) fprintf(stderr,"%s: %s needs a following argument\n",__progname,*av);
       errs ++;
       continue;
     }
#endif
#define WANTARG() do { if (++skip >= ac) goto needarg; } while (0)
    if (!strcmp(*av,"-set"))
     { whence = SEEK_SET;
       continue;
     }
    if (!strcmp(*av,"-cur") || !strcmp(*av,"-incr"))
     { whence = SEEK_CUR;
       continue;
     }
    if (!strcmp(*av,"-end") || !strcmp(*av,"-XTND"))
     { whence = SEEK_END;
       continue;
     }
#undef WANTARG
    if (! qflag) fprintf(stderr,"%s: unrecognized option `%s'\n",__progname,*av);
    errs ++;
  }
 if (errs) exit(qflag?EINVAL:1);
}

int main(int, char **);
int main(int ac, char **av)
{
 handleargs(ac,av);
 if (lseek(fd,offset,whence) < 0)
  { if (qflag) exit(errno);
    fprintf(stderr,"%s: %s\n",__progname,strerror(errno));
    exit(2);
  }
 exit(0);
}