redir.c

android-w.song.android.widget

	   * both sh and ksh leave the file descriptors open across execs.
	   * The Posix standard mentions only the exec builtin.
	   */
	  if ((flags & RX_CLEXEC) && (redirector > 2))
	    SET_CLOSE_ON_EXEC (redirector);
	}

      if (fd != redirector)
	{
#if defined (BUFFERED_INPUT)
	  if (INPUT_REDIRECT (ri))
	    close_buffered_fd (fd);
	  else
#endif /* !BUFFERED_INPUT */
	    close (fd);		/* Don't close what we just opened! */
	}

      /* If we are hacking both stdout and stderr, do the stderr
	 redirection here.  XXX - handle {var} here? */
      if (ri == r_err_and_out || ri == r_append_err_and_out)
	{
	  if (flags & RX_ACTIVE)
	    {
	      if (flags & RX_UNDOABLE)
		add_undo_redirect (2, ri, -1);
	      if (dup2 (1, 2) < 0)
		return (errno);
	    }
	}
      break;

    case r_reading_until:
    case r_deblank_reading_until:
    case r_reading_string:
      /* REDIRECTEE is a pointer to a WORD_DESC containing the text of
	 the new input.  Place it in a temporary file. */
      if (redirectee)
	{
	  fd = here_document_to_fd (redirectee, ri);

	  if (fd < 0)
	    {
	      heredoc_errno = errno;
	      return (HEREDOC_REDIRECT);
	    }

	  if (redirect->rflags & REDIR_VARASSIGN)
	    {
	      redirector = fcntl (fd, F_DUPFD, SHELL_FD_BASE);		/* XXX try this for now */
	      r = errno;
	      if (redirector < 0)
		sys_error (_("redirection error: cannot duplicate fd"));
	      REDIRECTION_ERROR (redirector, r, fd);
	    }

	  if (flags & RX_ACTIVE)
	    {
	      if (flags & RX_UNDOABLE)
	        {
		  /* Only setup to undo it if the thing to undo is active. */
		  if ((fd != redirector) && (fcntl (redirector, F_GETFD, 0) != -1))
		    r = add_undo_redirect (redirector, ri, -1);
		  else
		    r = add_undo_close_redirect (redirector);
		  if (r < 0 && (redirect->rflags & REDIR_VARASSIGN))
		    close (redirector);
		  REDIRECTION_ERROR (r, errno, fd);
	        }

#if defined (BUFFERED_INPUT)
	      check_bash_input (redirector);
#endif
	      if (redirect->rflags & REDIR_VARASSIGN)
		{
		  if ((r = redir_varassign (redirect, redirector)) < 0)
		    {
		      close (redirector);
		      close (fd);
		      return (r);	/* XXX */
		    }
		}
	      else if (fd != redirector && dup2 (fd, redirector) < 0)
		{
		  r = errno;
		  close (fd);
		  return (r);
		}

#if defined (BUFFERED_INPUT)
	      duplicate_buffered_stream (fd, redirector);
#endif

	      if ((flags & RX_CLEXEC) && (redirector > 2))
		SET_CLOSE_ON_EXEC (redirector);
	    }

	  if (fd != redirector)
#if defined (BUFFERED_INPUT)
	    close_buffered_fd (fd);
#else
	    close (fd);
#endif
	}
      break;

    case r_duplicating_input:
    case r_duplicating_output:
    case r_move_input:
    case r_move_output:
      if ((flags & RX_ACTIVE) && (redirect->rflags & REDIR_VARASSIGN))
        {
	  redirector = fcntl (redir_fd, F_DUPFD, SHELL_FD_BASE);		/* XXX try this for now */
	  r = errno;
	  if (redirector < 0)
	    sys_error (_("redirection error: cannot duplicate fd"));
	  REDIRECTION_ERROR (redirector, r, -1);
        }

      if ((flags & RX_ACTIVE) && (redir_fd != redirector))
	{
	  if (flags & RX_UNDOABLE)
	    {
	      /* Only setup to undo it if the thing to undo is active. */
	      if (fcntl (redirector, F_GETFD, 0) != -1)
		r = add_undo_redirect (redirector, ri, redir_fd);
	      else
		r = add_undo_close_redirect (redirector);
	      if (r < 0 && (redirect->rflags & REDIR_VARASSIGN))
		close (redirector);
	      REDIRECTION_ERROR (r, errno, -1);
	    }
#if defined (BUFFERED_INPUT)
	  check_bash_input (redirector);
#endif
	  if (redirect->rflags & REDIR_VARASSIGN)
	    {
	      if ((r = redir_varassign (redirect, redirector)) < 0)
		{
		  close (redirector);
		  return (r);	/* XXX */
		}
	    }
	  /* This is correct.  2>&1 means dup2 (1, 2); */
	  else if (dup2 (redir_fd, redirector) < 0)
	    return (errno);

#if defined (BUFFERED_INPUT)
	  if (ri == r_duplicating_input || ri == r_move_input)
	    duplicate_buffered_stream (redir_fd, redirector);
#endif /* BUFFERED_INPUT */

	  /* First duplicate the close-on-exec state of redirectee.  dup2
	     leaves the flag unset on the new descriptor, which means it
	     stays open.  Only set the close-on-exec bit for file descriptors
	     greater than 2 in any case, since 0-2 should always be open
	     unless closed by something like `exec 2<&-'.  It should always
	     be safe to set fds > 2 to close-on-exec if they're being used to
	     save file descriptors < 2, since we don't need to preserve the
	     state of the close-on-exec flag for those fds -- they should
	     always be open. */
	  /* if ((already_set || set_unconditionally) && (ok_to_set))
		set_it () */
#if 0
	  if (((fcntl (redir_fd, F_GETFD, 0) == 1) || redir_fd < 2 || (flags & RX_CLEXEC)) &&
	       (redirector > 2))
#else
	  if (((fcntl (redir_fd, F_GETFD, 0) == 1) || (redir_fd < 2 && (flags & RX_INTERNAL)) || (flags & RX_CLEXEC)) &&
	       (redirector > 2))
#endif
	    SET_CLOSE_ON_EXEC (redirector);

	  /* When undoing saving of non-standard file descriptors (>=3) using
	     file descriptors >= SHELL_FD_BASE, we set the saving fd to be
	     close-on-exec and use a flag to decide how to set close-on-exec
	     when the fd is restored. */
	  if ((redirect->flags & RX_INTERNAL) && (redirect->flags & RX_SAVCLEXEC) && redirector >= 3 && redir_fd >= SHELL_FD_BASE)
	    SET_OPEN_ON_EXEC (redirector);
	    
	  /* dup-and-close redirection */
	  if (ri == r_move_input || ri == r_move_output)
	    {
	      xtrace_fdchk (redir_fd);

	      close (redir_fd);
#if defined (COPROCESS_SUPPORT)
	      coproc_fdchk (redir_fd);	/* XXX - loses coproc fds */
#endif
	    }
	}
      break;

    case r_close_this:
      if (flags & RX_ACTIVE)
	{
	  if (redirect->rflags & REDIR_VARASSIGN)
	    {
	      redirector = redir_varvalue (redirect);
	      if (redirector < 0)
		return AMBIGUOUS_REDIRECT;
	    }

	  r = 0;
	  if ((flags & RX_UNDOABLE) && (fcntl (redirector, F_GETFD, 0) != -1))
	    {
	      r = add_undo_redirect (redirector, ri, -1);
	      REDIRECTION_ERROR (r, errno, redirector);
	    }

#if defined (COPROCESS_SUPPORT)
	  coproc_fdchk (redirector);
#endif
	  xtrace_fdchk (redirector);

#if defined (BUFFERED_INPUT)
	  check_bash_input (redirector);
	  close_buffered_fd (redirector);
#else /* !BUFFERED_INPUT */
	  close (redirector);
#endif /* !BUFFERED_INPUT */
	}
      break;

    case r_duplicating_input_word:
    case r_duplicating_output_word:
      break;
    }
  return (0);
}

/* Remember the file descriptor associated with the slot FD,
   on REDIRECTION_UNDO_LIST.  Note that the list will be reversed
   before it is executed.  Any redirections that need to be undone
   even if REDIRECTION_UNDO_LIST is discarded by the exec builtin
   are also saved on EXEC_REDIRECTION_UNDO_LIST.  FDBASE says where to
   start the duplicating.  If it's less than SHELL_FD_BASE, we're ok,
   and can use SHELL_FD_BASE (-1 == don't care).  If it's >= SHELL_FD_BASE,
   we have to make sure we don't use fdbase to save a file descriptor,
   since we're going to use it later (e.g., make sure we don't save fd 0
   to fd 10 if we have a redirection like 0<&10).  If the value of fdbase
   puts the process over its fd limit, causing fcntl to fail, we try
   again with SHELL_FD_BASE.  Return 0 on success, -1 on error. */
static int
add_undo_redirect (fd, ri, fdbase)
     int fd;
     enum r_instruction ri;
     int fdbase;
{
  int new_fd, clexec_flag;
  REDIRECT *new_redirect, *closer, *dummy_redirect;
  REDIRECTEE sd;

  new_fd = fcntl (fd, F_DUPFD, (fdbase < SHELL_FD_BASE) ? SHELL_FD_BASE : fdbase+1);
  if (new_fd < 0)
    new_fd = fcntl (fd, F_DUPFD, SHELL_FD_BASE);

  if (new_fd < 0)
    {
      sys_error (_("redirection error: cannot duplicate fd"));
      return (-1);
    }

  clexec_flag = fcntl (fd, F_GETFD, 0);

  sd.dest = new_fd;
  rd.dest = 0;
  closer = make_redirection (sd, r_close_this, rd, 0);
  closer->flags |= RX_INTERNAL;
  dummy_redirect = copy_redirects (closer);

  sd.dest = fd;
  rd.dest = new_fd;
  if (fd == 0)
    new_redirect = make_redirection (sd, r_duplicating_input, rd, 0);
  else
    new_redirect = make_redirection (sd, r_duplicating_output, rd, 0);
  new_redirect->flags |= RX_INTERNAL;
  if (clexec_flag == 0 && fd >= 3 && new_fd >= SHELL_FD_BASE)
    new_redirect->flags |= RX_SAVCLEXEC;
  new_redirect->next = closer;

  closer->next = redirection_undo_list;
  redirection_undo_list = new_redirect;

  /* Save redirections that need to be undone even if the undo list
     is thrown away by the `exec' builtin. */
  add_exec_redirect (dummy_redirect);

  /* experimental:  if we're saving a redirection to undo for a file descriptor
     above SHELL_FD_BASE, add a redirection to be undone if the exec builtin
     causes redirections to be discarded.  There needs to be a difference
     between fds that are used to save other fds and then are the target of
     user redirections and fds that are just the target of user redirections.
     We use the close-on-exec flag to tell the difference; fds > SHELL_FD_BASE
     that have the close-on-exec flag set are assumed to be fds used internally
     to save others. */
  if (fd >= SHELL_FD_BASE && ri != r_close_this && clexec_flag)
    {
      sd.dest = fd;
      rd.dest = new_fd;
      new_redirect = make_redirection (sd, r_duplicating_output, rd, 0);
      new_redirect->flags |= RX_INTERNAL;

      add_exec_redirect (new_redirect);
    }

  /* File descriptors used only for saving others should always be
     marked close-on-exec.  Unfortunately, we have to preserve the
     close-on-exec state of the file descriptor we are saving, since
     fcntl (F_DUPFD) sets the new file descriptor to remain open
     across execs.  If, however, the file descriptor whose state we
     are saving is <= 2, we can just set the close-on-exec flag,
     because file descriptors 0-2 should always be open-on-exec,
     and the restore above in do_redirection() will take care of it. */
  if (clexec_flag || fd < 3)
    SET_CLOSE_ON_EXEC (new_fd);
  else if (redirection_undo_list->flags & RX_SAVCLEXEC)
    SET_CLOSE_ON_EXEC (new_fd);

  return (0);
}

/* Set up to close FD when we are finished with the current command
   and its redirections.  Return 0 on success, -1 on error. */
static int
add_undo_close_redirect (fd)
     int fd;
{
  REDIRECT *closer;
  REDIRECTEE sd;

  sd.dest = fd;
  rd.dest = 0;
  closer = make_redirection (sd, r_close_this, rd, 0);
  closer->flags |= RX_INTERNAL;
  closer->next = redirection_undo_list;
  redirection_undo_list = closer;

  return 0;
}

static void
add_exec_redirect (dummy_redirect)
     REDIRECT *dummy_redirect;
{
  dummy_redirect->next = exec_redirection_undo_list;
  exec_redirection_undo_list = dummy_redirect;
}

/* Return 1 if the redirection specified by RI and REDIRECTOR alters the
   standard input. */
static int
stdin_redirection (ri, redirector)
     enum r_instruction ri;
     int redirector;
{
  switch (ri)
    {
    case r_input_direction:
    case r_inputa_direction:
    case r_input_output:
    case r_reading_until:
    case r_deblank_reading_until:
    case r_reading_string:
      return (1);
    case r_duplicating_input:
    case r_duplicating_input_word:
    case r_close_this:
      return (redirector == 0);
    case r_output_direction:
    case r_appending_to:
    case r_duplicating_output:
    case r_err_and_out:
    case r_append_err_and_out:
    case r_output_force:
    case r_duplicating_output_word:
      return (0);
    }
  return (0);
}

/* Return non-zero if any of the redirections in REDIRS alter the standard
   input. */
int
stdin_redirects (redirs)
     REDIRECT *redirs;
{
  REDIRECT *rp;
  int n;

  for (n = 0, rp = redirs; rp; rp = rp->next)
    if ((rp->rflags & REDIR_VARASSIGN) == 0)
      n += stdin_redirection (rp->instruction, rp->redirector.dest);
  return n;
}

/* These don't yet handle array references */
static int
redir_varassign (redir, fd)
     REDIRECT *redir;
     int fd;
{
  WORD_DESC *w;
  SHELL_VAR *v;

  w = redir->redirector.filename;
  v = bind_var_to_int (w->word, fd);
  if (v == 0 || readonly_p (v) || noassign_p (v))
    return BADVAR_REDIRECT;

  return 0;
}

static int
redir_varvalue (redir)
     REDIRECT *redir;
{
  SHELL_VAR *v;
  char *val;
  intmax_t vmax;
  int i;

  /* XXX - handle set -u here? */
  v = find_variable (redir->redirector.filename->word);
  if (v == 0 || invisible_p (v))
    return -1;

  val = get_variable_value (v);
  if (val == 0 || *val == 0)
    return -1;

  if (legal_number (val, &vmax) < 0)
    return -1;

  i = vmax;	/* integer truncation */
  return i;
}