text: /* rename.c -- BSD compatible directory function for System V
     Copyright (C) 1988, 1990 Free Software Foundation, Inc.
  
     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, 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., 675 Mass Ave, Cambridge, MA 02139, USA.  */
  
  #ifdef HAVE_CONFIG_H
  #include <config.h>
  #endif
  
  #include <sys/types.h>
  #include <sys/stat.h>
  #include <errno.h>
  #ifndef errno
  extern int errno;
  #endif
  
  #ifdef STAT_MACROS_BROKEN
  #undef S_ISDIR
  #endif /* STAT_MACROS_BROKEN.  */
  
  #if !defined(S_ISDIR) && defined(S_IFDIR)
  #define S_ISDIR(m) (((m) & S_IFMT) == S_IFDIR)
  #endif
  
  /* Rename file FROM to file TO.
     Return 0 if successful, -1 if not. */
  
  int
  rename (from, to)
       char *from;
       char *to;
  {
    struct stat from_stats, to_stats;
    int pid, status;
  
    if (stat (from, &from_stats))
      return -1;
  
    /* Be careful not to unlink `from' if it happens to be equal to `to' or
       (on filesystems that silently truncate filenames after 14 characters)
       if `from' and `to' share the significant characters. */
    if (stat (to, &to_stats))
      {
        if (errno != ENOENT)
          return -1;
      }
    else
      {
        if ((from_stats.st_dev == to_stats.st_dev)
            && (from_stats.st_ino == to_stats.st_ino))
          /* `from' and `to' designate the same file on that filesystem. */
          return 0;
  
        if (unlink (to) && errno != ENOENT)
          return -1;
      }
  
    if (S_ISDIR (from_stats.st_mode))
      {
        /* Need a setuid root process to link and unlink directories. */
        pid = fork ();
        switch (pid)
  	{
  	case -1:		/* Error. */
  	  error (1, errno, "cannot fork");
  
  	case 0:			/* Child. */
  	  execl (MVDIR, "mvdir", from, to, (char *) 0);
  	  error (255, errno, "cannot run `%s'", MVDIR);
  
  	default:		/* Parent. */
  	  while (wait (&status) != pid)
  	    /* Do nothing. */ ;
  
  	  errno = 0;		/* mvdir printed the system error message. */
  	  if (status)
  	    return -1;
  	}
      }
    else
      {
        if (link (from, to))
  	return -1;
        if (unlink (from) && errno != ENOENT)
  	{
  	  unlink (to);
  	  return -1;
  	}
      }
    return 0;
  }
  