text: /* UNIX V7 source code: see /COPYRIGHT or www.tuhs.org for details. */
  
  /*
   * cp oldfile newfile
   */
  
  #define	BSIZE	512
  #include <stdio.h>
  #include <sys/types.h>
  #include <sys/stat.h>
  struct	stat	stbuf1, stbuf2;
  char	iobuf[BSIZE];
  
  main(argc, argv)
  char *argv[];
  {
  	register i, r;
  
  	if (argc < 3) 
  		goto usage;
  	if (argc > 3) {
  		if (stat(argv[argc-1], &stbuf2) < 0)
  			goto usage;
  		if ((stbuf2.st_mode&S_IFMT) != S_IFDIR) 
  			goto usage;
  	}
  	r = 0;
  	for(i=1; i<argc-1;i++)
  		r |= copy(argv[i], argv[argc-1]);
  	exit(r);
  usage:
  	fprintf(stderr, "Usage: cp: f1 f2; or cp f1 ... fn d2\n");
  	exit(1);
  }
  
  copy(from, to)
  char *from, *to;
  {
  	int fold, fnew, n;
  	register char *p1, *p2, *bp;
  	int mode;
  	if ((fold = open(from, 0)) < 0) {
  		fprintf(stderr, "cp: cannot open %s\n", from);
  		return(1);
  	}
  	fstat(fold, &stbuf1);
  	mode = stbuf1.st_mode;
  	/* is target a directory? */
  	if (stat(to, &stbuf2) >=0 &&
  	   (stbuf2.st_mode&S_IFMT) == S_IFDIR) {
  		p1 = from;
  		p2 = to;
  		bp = iobuf;
  		while(*bp++ = *p2++)
  			;
  		bp[-1] = '/';
  		p2 = bp;
  		while(*bp = *p1++)
  			if (*bp++ == '/')
  				bp = p2;
  		to = iobuf;
  	}
  	if (stat(to, &stbuf2) >= 0) {
  		if (stbuf1.st_dev == stbuf2.st_dev &&
  		   stbuf1.st_ino == stbuf2.st_ino) {
  			fprintf(stderr, "cp: cannot copy file to itself.\n");
  			return(1);
  		}
  	}
  	if ((fnew = creat(to, mode)) < 0) {
  		fprintf(stderr, "cp: cannot create %s\n", to);
  		close(fold);
  		return(1);
  	}
  	while(n = read(fold,  iobuf,  BSIZE)) {
  		if (n < 0) {
  			fprintf(stderr, "cp: read error\n");
  			close(fold);
  			close(fnew);
  			return(1);
  		} else
  			if (write(fnew, iobuf, n) != n) {
  				fprintf(stderr, "cp: write error.\n");
  				close(fold);
  				close(fnew);
  				return(1);
  			}
  	}
  	close(fold);
  	close(fnew);
  	return(0);
  }
  