Implemented suspending of emacsclient frames.

lib-src/emacsclient.c (quote_file_name): Renamed to quote_argument.
(unquote_argument, handle_sigcont, handle_sigtstp): New functions.
(out, in): New global variables for communicating with the Emacs process.
(init_signals): Set up handlers for SIGCONT, SIGTSTP and SIGTTOU.
(main): Changed out and in to global variables.  Prepend `-eval' or
'-file' to each argument.  Use fsync to force sending the strings to Emacs.
Removed obsolete -bad-version code.  Support the -suspend command.
Cleaned up newline handling.

lisp/frame.el (suspend-frame): New function.
Substitute key definition of suspend-emacs with suspend-frame.

lisp/server.el (server-log): Cosmetic change in log format.
(server-handle-delete-tty, server-handle-delete-frame): Added logging.
(server-handle-suspend-tty, server-quote-arg): New functions.
(server-start): Install server-handle-suspend-tty.
(server-process-filter): Reorganized source code for clarity.
Implemented -resume, -suspend and -ignore commands.

lisp/term/x-win.el (x-initialize-window-system): Don't change the
binding of C-z.

src/cm.c: Replaced TTY_INPUT, TTY_OUTPUT, TTY_TERMSCRIPT calls with
their macro expansion.
src/dispnew.c: Ditto.
src/frame.c: Ditto.
src/keyboard.c: Ditto.
src/sysdep.c: Ditto.

src/keyboard.c (tty_read_avail_input): Don't read if the terminal is
suspended.
src/sysdep.c (discard_tty_input, init_sys_modes, reset_sys_modes): Ditto.
src/term.c (tty_set_terminal_modes, tty_reset_terminal_modes): Ditto.

src/term.c (Vsuspend_tty_functions, Vresume_tty_functions): New hooks.
(syms_of_term): Defvar them.
(term_init): Don't allow opening a new frame on a suspended tty device.
(Fsuspend_tty, Fresume_tty): New functions.
(syms_of_term): Defsubr them.

src/termchar.c (struct tty_display_info): Update documentation of
input and output.
(TTY_INPUT, TTY_OUTPUT, TTY_TERMSCRIPT): Removed.


git-archimport-id: lorentey@elte.hu--2004/emacs--multi-tty--0--patch-105

8 files changed, 309 insertions, 128 deletions

diff --git a/src/cm.c b/src/cm.c
index 5ce03483b06..9f9cc0e0a34 100644
--- a/src/cm.c
+++ b/src/cm.c
@@ -64,9 +64,9 @@ int
 cmputc (c)
      char c;
 {
-  if (TTY_TERMSCRIPT (current_tty))
-    putc (c & 0177, TTY_TERMSCRIPT (current_tty));
-  putc (c & 0177, TTY_OUTPUT (current_tty));
+  if (current_tty->termscript)
+    putc (c & 0177, current_tty->termscript);
+  putc (c & 0177, current_tty->output);
   return c;
 }
 
@@ -136,12 +136,12 @@ cmcheckmagic (struct tty_display_info *tty)
     {
       if (!MagicWrap (tty) || curY (tty) >= FrameRows (tty) - 1)
         abort ();
-      if (TTY_TERMSCRIPT (tty))
-        putc ('\r', TTY_TERMSCRIPT (tty));
-      putc ('\r', TTY_OUTPUT (tty));
-      if (TTY_TERMSCRIPT (tty))
-        putc ('\n', TTY_TERMSCRIPT (tty));
-      putc ('\n', TTY_OUTPUT (tty));
+      if (tty->termscript)
+        putc ('\r', tty->termscript);
+      putc ('\r', tty->output);
+      if (tty->termscript)
+        putc ('\n', tty->termscript);
+      putc ('\n', tty->output);
       curX (tty) = 0;
       curY (tty)++;
     }
diff --git a/src/dispnew.c b/src/dispnew.c
index aaf3c440f34..8a3d7013c3e 100644
--- a/src/dispnew.c
+++ b/src/dispnew.c
@@ -3316,7 +3316,7 @@ DEFUN ("redraw-frame", Fredraw_frame, Sredraw_frame, 1, 1, 0,
   clear_current_matrices (f);
   update_end (f);
   if (FRAME_TERMCAP_P (f))
-    fflush (TTY_OUTPUT (FRAME_TTY (f)));
+    fflush (FRAME_TTY (f)->output);
   windows_or_buffers_changed++;
   /* Mark all windows as inaccurate, so that every window will have
      its redisplay done.  */
@@ -3659,7 +3659,7 @@ direct_output_for_insert (g)
   update_end (f);
   updated_row = NULL;
   if (FRAME_TERMCAP_P (f))
-    fflush (TTY_OUTPUT (FRAME_TTY (f)));
+    fflush (FRAME_TTY (f)->output);
 
   TRACE ((stderr, "direct output for insert\n"));
   mark_window_display_accurate (it.window, 1);
@@ -3751,7 +3751,7 @@ direct_output_forward_char (n)
     }
 
   if (FRAME_TERMCAP_P (f))
-    fflush (TTY_OUTPUT (FRAME_TTY (f)));
+    fflush (FRAME_TTY (f)->output);
   redisplay_performed_directly_p = 1;
   return 1;
 }
@@ -3849,9 +3849,9 @@ update_frame (f, force_p, inhibit_hairy_id_p)
 
       if (FRAME_TERMCAP_P (f))
         {
-          if (TTY_TERMSCRIPT (FRAME_TTY (f)))
-            fflush (TTY_TERMSCRIPT (FRAME_TTY (f)));
-          fflush (TTY_OUTPUT (FRAME_TTY (f)));
+          if (FRAME_TTY (f)->termscript)
+            fflush (FRAME_TTY (f)->termscript);
+          fflush (FRAME_TTY (f)->output);
         }
 
       /* Check window matrices for lost pointers.  */
@@ -5133,18 +5133,18 @@ update_frame_1 (f, force_p, inhibit_id_p)
                  Also flush out if likely to have more than 1k buffered
                  otherwise.   I'm told that some telnet connections get
                  really screwed by more than 1k output at once.  */
-              int outq = PENDING_OUTPUT_COUNT (TTY_OUTPUT (FRAME_TTY (f)));
+              int outq = PENDING_OUTPUT_COUNT (FRAME_TTY (f)->output);
               if (outq > 900
                   || (outq > 20 && ((i - 1) % preempt_count == 0)))
                 {
-                  fflush (TTY_OUTPUT (FRAME_TTY (f)));
+                  fflush (FRAME_TTY (f)->output);
                   if (preempt_count == 1)
                     {
 #ifdef EMACS_OUTQSIZE
                       if (EMACS_OUTQSIZE (0, &outq) < 0)
                         /* Probably not a tty.  Ignore the error and reset
                            the outq count.  */
-                        outq = PENDING_OUTPUT_COUNT (TTY_OUTPUT (FRAME_TTY (f)));
+                        outq = PENDING_OUTPUT_COUNT (FRAME_TTY (f->output));
 #endif
                       outq *= 10;
                       if (baud_rate <= outq && baud_rate > 0)
@@ -5999,7 +5999,7 @@ window_change_signal (signalnum) /* If we don't have an argument, */
     if (! tty->term_initted)
       continue;
 
-    get_tty_size (fileno (TTY_INPUT (tty)), &width, &height);
+    get_tty_size (fileno (tty->input), &width, &height);
     
     {
       Lisp_Object tail, frame;
@@ -6211,15 +6211,22 @@ FILE = nil means just close any termscript file currently open.  */)
      (file)
      Lisp_Object file;
 {
-  if (TTY_TERMSCRIPT (CURTTY ()) != 0)
-    fclose (TTY_TERMSCRIPT (CURTTY ()));
-  TTY_TERMSCRIPT (CURTTY ()) = 0;
+  struct tty_display_info *tty;
+
+  if (! FRAME_TERMCAP_P (SELECTED_FRAME ()))
+    error ("Current frame is not on a tty device");
+
+  tty = CURTTY ();
+
+  if (tty->termscript != 0)
+    fclose (tty->termscript);
+  tty->termscript = 0;
 
   if (! NILP (file))
     {
       file = Fexpand_file_name (file, Qnil);
-      TTY_TERMSCRIPT (CURTTY ()) = fopen (SDATA (file), "w");
-      if (TTY_TERMSCRIPT (CURTTY ()) == 0)
+      tty->termscript = fopen (SDATA (file), "w");
+      if (tty->termscript == 0)
         report_file_error ("Opening termscript", Fcons (file, Qnil));
     }
   return Qnil;
@@ -6233,20 +6240,23 @@ Control characters in STRING will have terminal-dependent effects.  */)
      (string)
      Lisp_Object string;
 {
+  struct tty_display_info *tty;
+
   /* ??? Perhaps we should do something special for multibyte strings here.  */
   CHECK_STRING (string);
+
   if (! FRAME_TERMCAP_P (SELECTED_FRAME ()))
     error ("Current frame is not on a tty device");
+
+  tty = CURTTY ();
   
-  if (TTY_TERMSCRIPT (CURTTY ()))
+  if (tty->termscript)
     {
-      fwrite (SDATA (string), 1, SBYTES (string),
-              TTY_TERMSCRIPT (CURTTY ()));
-      fflush (TTY_TERMSCRIPT (CURTTY ()));
+      fwrite (SDATA (string), 1, SBYTES (string), tty->termscript);
+      fflush (tty->termscript);
     }
-  fwrite (SDATA (string), 1, SBYTES (string),
-          TTY_OUTPUT (CURTTY ()));
-  fflush (TTY_OUTPUT (CURTTY ()));
+  fwrite (SDATA (string), 1, SBYTES (string), tty->output);
+  fflush (tty->output);
   return Qnil;
 }
 
@@ -6265,7 +6275,7 @@ terminate any keyboard macro currently executing.  */)
       else
         ring_bell ();
       if (FRAME_TERMCAP_P (XFRAME (selected_frame)))
-        fflush (TTY_OUTPUT (CURTTY ()));
+        fflush (CURTTY ()->output);
     }
   else
     bitch_at_user ();
@@ -6283,7 +6293,7 @@ bitch_at_user ()
   else
     ring_bell ();
   if (FRAME_TERMCAP_P (XFRAME (selected_frame)))
-    fflush (TTY_OUTPUT (CURTTY ()));
+    fflush (CURTTY ()->output);
 }
 
 
diff --git a/src/frame.c b/src/frame.c
index 8ffabfa8b89..c7b5491500f 100644
--- a/src/frame.c
+++ b/src/frame.c
@@ -667,7 +667,8 @@ and the `tty-type' parameter specifies the terminal type.  Example:
 
    (make-terminal-frame '((tty . "/dev/pts/5") (tty-type . "xterm")))
 
-Note that changing the size of one terminal frame automatically affects all.  */)
+Note that changing the size of one terminal frame automatically
+affects all frames on the same terminal device.  */)
      (parms)
      Lisp_Object parms;
 {
@@ -742,7 +743,7 @@ Note that changing the size of one terminal frame automatically affects all.  */
 
   {
     int width, height;
-    get_tty_size (fileno (TTY_INPUT (FRAME_TTY (f))), &width, &height);
+    get_tty_size (fileno (FRAME_TTY (f)->input), &width, &height);
     change_frame_size (f, height, width, 0, 0, 0);
   }
   
diff --git a/src/keyboard.c b/src/keyboard.c
index 2c6edc68f99..5bcd53a260f 100644
--- a/src/keyboard.c
+++ b/src/keyboard.c
@@ -6704,10 +6704,13 @@ tty_read_avail_input (struct display *display,
   if (! tty->term_initted)      /* In case we get called during bootstrap. */
     return 0;
 
+  if (! tty->input)
+    return 0;                   /* The terminal is suspended. */
+
   /* Determine how many characters we should *try* to read.  */
 #ifdef FIONREAD
   /* Find out how much input is available.  */
-  if (ioctl (fileno (TTY_INPUT (tty)), FIONREAD, &n_to_read) < 0)
+  if (ioctl (fileno (tty->input), FIONREAD, &n_to_read) < 0)
     {
       if (! noninteractive)
         return -2;          /* Close this display. */
@@ -6722,7 +6725,7 @@ tty_read_avail_input (struct display *display,
 #if defined (USG) || defined (DGUX) || defined(CYGWIN)
   /* Read some input if available, but don't wait.  */
   n_to_read = sizeof cbuf;
-  fcntl (fileno (TTY_INPUT (tty)), F_SETFL, O_NDELAY);
+  fcntl (fileno (tty->input), F_SETFL, O_NDELAY);
 #else
   you lose;
 #endif
@@ -6732,7 +6735,7 @@ tty_read_avail_input (struct display *display,
      NREAD is set to the number of chars read.  */
   do
     {
-      nread = emacs_read (fileno (TTY_INPUT (tty)), cbuf, n_to_read);
+      nread = emacs_read (fileno (tty->input), cbuf, n_to_read);
       /* POSIX infers that processes which are not in the session leader's
          process group won't get SIGHUP's at logout time.  BSDI adheres to
          this part standard and returns -1 from read (0) with errno==EIO
@@ -6770,7 +6773,7 @@ tty_read_avail_input (struct display *display,
 
 #ifndef FIONREAD
 #if defined (USG) || defined (DGUX) || defined (CYGWIN)
-  fcntl (fileno (TTY_INPUT (tty)), F_SETFL, 0);
+  fcntl (fileno (tty->input), F_SETFL, 0);
 #endif /* USG or DGUX or CYGWIN */
 #endif /* no FIONREAD */
 
@@ -10168,7 +10171,7 @@ On such systems, Emacs starts a subshell instead of suspending.  */)
     call1 (Vrun_hooks, intern ("suspend-hook"));
 
   GCPRO1 (stuffstring);
-  get_tty_size (fileno (TTY_INPUT (CURTTY ())), &old_width, &old_height);
+  get_tty_size (fileno (CURTTY ()->input), &old_width, &old_height);
   reset_all_sys_modes ();
   /* sys_suspend can get an error if it tries to fork a subshell
      and the system resources aren't available for that.  */
@@ -10184,7 +10187,7 @@ On such systems, Emacs starts a subshell instead of suspending.  */)
   /* Check if terminal/window size has changed.
      Note that this is not useful when we are running directly
      with a window system; but suspend should be disabled in that case.  */
-  get_tty_size (fileno (TTY_INPUT (CURTTY ())), &width, &height);
+  get_tty_size (fileno (CURTTY ()->input), &width, &height);
   if (width != old_width || height != old_height)
     change_frame_size (SELECTED_FRAME (), height, width, 0, 0, 0);
 
diff --git a/src/sysdep.c b/src/sysdep.c
index febf59253e1..d4693f99a94 100644
--- a/src/sysdep.c
+++ b/src/sysdep.c
@@ -274,7 +274,7 @@ discard_tty_input ()
 
 #ifdef VMS
   end_kbd_input ();
-  SYS$QIOW (0, fileno (TTY_INPUT (CURTTY())), IO$_READVBLK|IO$M_PURGE, input_iosb, 0, 0,
+  SYS$QIOW (0, fileno (CURTTY()->input), IO$_READVBLK|IO$M_PURGE, input_iosb, 0, 0,
             &buf.main, 0, 0, terminator_mask, 0, 0);
   queue_kbd_input ();
 #else /* not VMS */
@@ -284,7 +284,8 @@ discard_tty_input ()
     for (tty = tty_list; tty; tty = tty->next)
       {
         int zero = 0;
-        ioctl (fileno (TTY_INPUT (tty)), TIOCFLUSH, &zero);
+        if (tty->input)
+          ioctl (fileno (tty->input), TIOCFLUSH, &zero);
       }
   }
 #else /* not Apollo */
@@ -296,8 +297,11 @@ discard_tty_input ()
     struct tty_display_info *tty;
     for (tty = tty_list; tty; tty = tty->next)
       {
-        EMACS_GET_TTY (fileno (TTY_INPUT (tty)), &buf);
-        EMACS_SET_TTY (fileno (TTY_INPUT (tty)), &buf, 0);
+        if (tty->input)         /* Is the device suspended? */
+          {
+            EMACS_GET_TTY (fileno (tty->input), &buf);
+            EMACS_SET_TTY (fileno (tty->input), &buf, 0);
+          }
       }
   }
 #endif /* not MSDOS */
@@ -322,7 +326,7 @@ stuff_char (char c)
 
 /* Should perhaps error if in batch mode */
 #ifdef TIOCSTI
-  ioctl (fileno (TTY_INPUT (CURTTY())), TIOCSTI, &c);
+  ioctl (fileno (CURTTY()->input), TIOCSTI, &c);
 #else /* no TIOCSTI */
   error ("Cannot stuff terminal input characters in this version of Unix");
 #endif /* no TIOCSTI */
@@ -1005,7 +1009,7 @@ request_sigio ()
     return;
 
   /* XXX CURTTY() is bogus here. */
-  ioctl (fileno (TTY_INPUT (CURTTY ())), FIOASYNC, &on);
+  ioctl (fileno (CURTTY ()->input), FIOASYNC, &on);
   interrupts_deferred = 0;
 }
 
@@ -1018,7 +1022,7 @@ unrequest_sigio ()
     return;
 
   /* XXX CURTTY() is bogus here. */
-  ioctl (fileno (TTY_INPUT (CURTTY ())), FIOASYNC, &off);
+  ioctl (fileno (CURTTY ()->input), FIOASYNC, &off);
   interrupts_deferred = 1;
 }
 
@@ -1366,6 +1370,9 @@ nil means don't delete them until `list-processes' is run.  */);
   if (noninteractive)
     return;
 
+  if (!tty_out->output)
+    return;                     /* The tty is suspended. */
+  
 #ifdef VMS
   if (!input_ef)
     input_ef = get_kbd_event_flag ();
@@ -1404,13 +1411,13 @@ nil means don't delete them until `list-processes' is run.  */);
      unconditionally will not cause any problems. */
   if (! read_socket_hook && EQ (Vinitial_window_system, Qnil))
 #endif
-    narrow_foreground_group (fileno (TTY_INPUT (tty_out)));
+    narrow_foreground_group (fileno (tty_out->input));
 #endif
 
   if (! tty_out->old_tty)
     tty_out->old_tty = (struct emacs_tty *) xmalloc (sizeof (struct emacs_tty));
       
-  EMACS_GET_TTY (fileno (TTY_INPUT (tty_out)), tty_out->old_tty);
+  EMACS_GET_TTY (fileno (tty_out->input), tty_out->old_tty);
 
   tty = *tty_out->old_tty;
 
@@ -1626,23 +1633,23 @@ nil means don't delete them until `list-processes' is run.  */);
   dos_ttraw ();
 #endif
 
-  EMACS_SET_TTY (fileno (TTY_INPUT (tty_out)), &tty, 0);
+  EMACS_SET_TTY (fileno (tty_out->input), &tty, 0);
 
   /* This code added to insure that, if flow-control is not to be used,
      we have an unlocked terminal at the start. */
 
 #ifdef TCXONC
-  if (!tty_out->flow_control) ioctl (fileno (TTY_INPUT (tty_out)), TCXONC, 1);
+  if (!tty_out->flow_control) ioctl (fileno (tty_out->input), TCXONC, 1);
 #endif
 #ifndef APOLLO
 #ifdef TIOCSTART
-  if (!tty_out->flow_control) ioctl (fileno (TTY_INPUT (tty_out)), TIOCSTART, 0);
+  if (!tty_out->flow_control) ioctl (fileno (tty_out->input), TIOCSTART, 0);
 #endif
 #endif
 
 #if defined (HAVE_TERMIOS) || defined (HPUX9)
 #ifdef TCOON
-  if (!tty_out->flow_control) tcflow (fileno (TTY_INPUT (tty_out)), TCOON);
+  if (!tty_out->flow_control) tcflow (fileno (tty_out->input), TCOON);
 #endif
 #endif
 
@@ -1662,7 +1669,7 @@ nil means don't delete them until `list-processes' is run.  */);
 
 #ifdef VMS
 /*  Appears to do nothing when in PASTHRU mode.
-      SYS$QIOW (0, fileno (TTY_INPUT (tty_out)), IO$_SETMODE|IO$M_OUTBAND, 0, 0, 0,
+      SYS$QIOW (0, fileno (tty_out->input), IO$_SETMODE|IO$M_OUTBAND, 0, 0, 0,
                 interrupt_signal, oob_chars, 0, 0, 0, 0);
 */
   queue_kbd_input (0);
@@ -1673,10 +1680,10 @@ nil means don't delete them until `list-processes' is run.  */);
 #ifdef F_GETOWN         /* F_SETFL does not imply existence of F_GETOWN */
   if (interrupt_input)
     {
-      old_fcntl_owner[fileno (TTY_INPUT (tty_out))] =
-        fcntl (fileno (TTY_INPUT (tty_out)), F_GETOWN, 0);
-      fcntl (fileno (TTY_INPUT (tty_out)), F_SETOWN, getpid ());
-      init_sigio (fileno (TTY_INPUT (tty_out)));
+      old_fcntl_owner[fileno (tty_out->input)] =
+        fcntl (fileno (tty_out->input), F_GETOWN, 0);
+      fcntl (fileno (tty_out->input), F_SETOWN, getpid ());
+      init_sigio (fileno (tty_out->input));
     }
 #endif /* F_GETOWN */
 #endif /* F_SETOWN_BUG */
@@ -1684,7 +1691,7 @@ nil means don't delete them until `list-processes' is run.  */);
 
 #ifdef BSD4_1
   if (interrupt_input)
-    init_sigio (fileno (TTY_INPUT (tty_out)));
+    init_sigio (fileno (tty_out->input));
 #endif
 
 #ifdef VMS  /* VMS sometimes has this symbol but lacks setvbuf.  */
@@ -1694,9 +1701,9 @@ nil means don't delete them until `list-processes' is run.  */);
   /* This symbol is defined on recent USG systems.
      Someone says without this call USG won't really buffer the file
      even with a call to setbuf. */
-  setvbuf (TTY_OUTPUT (tty_out), (char *) _sobuf, _IOFBF, sizeof _sobuf);
+  setvbuf (tty_out->output, (char *) _sobuf, _IOFBF, sizeof _sobuf);
 #else
-  setbuf (TTY_OUTPUT (tty_out), (char *) _sobuf);
+  setbuf (tty_out->output, (char *) _sobuf);
 #endif
 
   tty_set_terminal_modes (tty_out->display);
@@ -1867,10 +1874,13 @@ reset_sys_modes (tty_out)
   if (!tty_out->term_initted)
     return;
 
+  if (!tty_out->output)
+    return;                     /* The tty is suspended. */
+  
   /* Go to and clear the last line of the terminal. */
 
   cmgoto (tty_out, FrameRows (tty_out) - 1, 0);
-
+  
   /* Code adapted from tty_clear_end_of_line. */
   if (tty_out->TS_clr_line)
     {
@@ -1880,13 +1890,13 @@ reset_sys_modes (tty_out)
     {                   /* have to do it the hard way */
       int i;
       turn_off_insert (tty_out);
-
+      
       for (i = curX (tty_out); i < FrameCols (tty_out) - 1; i++)
-        {
-          fputc (' ', TTY_OUTPUT (tty_out));
-        }
+        {
+          fputc (' ', tty_out->output);
+        }
     }
-
+  
   cmgoto (tty_out, FrameRows (tty_out) - 1, 0);
   fflush (tty_out->output);
   
@@ -1902,11 +1912,11 @@ reset_sys_modes (tty_out)
 #endif
 
   tty_reset_terminal_modes (tty_out->display);
-  fflush (TTY_OUTPUT (tty_out));
+  fflush (tty_out->output);
 #ifdef BSD_SYSTEM
 #ifndef BSD4_1
   /* Avoid possible loss of output when changing terminal modes.  */
-  fsync (fileno (TTY_OUTPUT (tty_out)));
+  fsync (fileno (tty_out->output));
 #endif
 #endif
 
@@ -1915,24 +1925,24 @@ reset_sys_modes (tty_out)
 #ifdef F_SETOWN         /* F_SETFL does not imply existence of F_SETOWN */
   if (interrupt_input)
     {
-      reset_sigio (fileno (TTY_INPUT (tty_out)));
-      fcntl (fileno (TTY_INPUT (tty_out)), F_SETOWN,
-             old_fcntl_owner[fileno (TTY_INPUT (tty_out))]);
+      reset_sigio (fileno (tty_out->input));
+      fcntl (fileno (tty_out->input), F_SETOWN,
+             old_fcntl_owner[fileno (tty_out->input)]);
     }
 #endif /* F_SETOWN */
 #endif /* F_SETOWN_BUG */
 #ifdef O_NDELAY
-  fcntl (fileno (TTY_INPUT (tty_out)), F_SETFL,
-         fcntl (fileno (TTY_INPUT (tty_out)), F_GETFL, 0) & ~O_NDELAY);
+  fcntl (fileno (tty_out->input), F_SETFL,
+         fcntl (fileno (tty_out->input), F_GETFL, 0) & ~O_NDELAY);
 #endif
 #endif /* F_SETFL */
 #ifdef BSD4_1
   if (interrupt_input)
-    reset_sigio (fileno (TTY_INPUT (tty_out)));
+    reset_sigio (fileno (tty_out->input));
 #endif /* BSD4_1 */
 
   if (tty_out->old_tty)
-    while (EMACS_SET_TTY (fileno (TTY_INPUT (tty_out)),
+    while (EMACS_SET_TTY (fileno (tty_out->input),
                           tty_out->old_tty, 0) < 0 && errno == EINTR)
       ;
 
@@ -1952,7 +1962,7 @@ reset_sys_modes (tty_out)
 #endif
 
 #ifdef BSD_PGRPS
-  widen_foreground_group (fileno (TTY_INPUT (tty_out)));
+  widen_foreground_group (fileno (tty_out->input));
 #endif
 }
 
@@ -2017,9 +2027,9 @@ init_vms_input ()
 {
   int status;
 
-  if (fileno (TTY_INPUT (CURTTY())) == 0)
+  if (fileno (CURTTY ()->input)) == 0)
     {
-      status = SYS$ASSIGN (&input_dsc, &fileno (TTY_INPUT (CURTTY())), 0, 0);
+      status = SYS$ASSIGN (&input_dsc, &fileno (CURTTY ()->input)), 0, 0);
       if (! (status & 1))
         LIB$STOP (status);
     }
@@ -2030,7 +2040,7 @@ init_vms_input ()
 void
 stop_vms_input ()
 {
-  return SYS$DASSGN (fileno (TTY_INPUT (CURTTY())));
+  return SYS$DASSGN (fileno (CURTTY ()->input)));
 }
 
 short input_buffer;
@@ -2046,7 +2056,7 @@ queue_kbd_input ()
 
   waiting_for_ast = 0;
   stop_input = 0;
-  status = SYS$QIO (0, fileno (TTY_INPUT (CURTTY())), IO$_READVBLK,
+  status = SYS$QIO (0, fileno (CURTTY()->input), IO$_READVBLK,
                     &input_iosb, kbd_input_ast, 1,
                     &input_buffer, 1, 0, terminator_mask, 0, 0);
 }
@@ -2163,7 +2173,7 @@ end_kbd_input ()
 #endif
   if (LIB$AST_IN_PROG ())  /* Don't wait if suspending from kbd_buffer_store_event! */
     {
-      SYS$CANCEL (fileno (TTY_INPUT (CURTTY())));
+      SYS$CANCEL (fileno (CURTTY()->input));
       return;
     }
 
@@ -2172,7 +2182,7 @@ end_kbd_input ()
   SYS$CLREF (input_ef);
   waiting_for_ast = 1;
   stop_input = 1;
-  SYS$CANCEL (fileno (TTY_INPUT (CURTTY())));
+  SYS$CANCEL (fileno (CURTTY()->input));
   SYS$SETAST (1);
   SYS$WAITFR (input_ef);
   waiting_for_ast = 0;
diff --git a/src/term.c b/src/term.c
index e3b176c51ea..785f2a3bb33 100644
--- a/src/term.c
+++ b/src/term.c
@@ -106,9 +106,15 @@ void delete_tty_output P_ ((struct frame *));
 
 Lisp_Object Vring_bell_function;
 
-/* Functions to call after a tty was deleted. */
+/* Functions to call after deleting a tty. */
 Lisp_Object Vdelete_tty_after_functions;
 
+/* Functions to call after suspending a tty. */
+Lisp_Object Vsuspend_tty_functions;
+
+/* Functions to call after resuming a tty. */
+Lisp_Object Vresume_tty_functions;
+
 /* Chain of all displays currently in use. */
 struct display *display_list;
 
@@ -231,10 +237,13 @@ tty_set_terminal_modes (struct display *display)
 {
   struct tty_display_info *tty = display->display_info.tty;
   
-  OUTPUT_IF (tty, tty->TS_termcap_modes);
-  OUTPUT_IF (tty, tty->TS_cursor_visible);
-  OUTPUT_IF (tty, tty->TS_keypad_mode);
-  losecursor (tty);
+  if (tty->output)
+    {
+      OUTPUT_IF (tty, tty->TS_termcap_modes);
+      OUTPUT_IF (tty, tty->TS_cursor_visible);
+      OUTPUT_IF (tty, tty->TS_keypad_mode);
+      losecursor (tty);
+    }
 }
 
 /* Reset termcap modes before exiting Emacs. */
@@ -243,16 +252,19 @@ void
 tty_reset_terminal_modes (struct display *display)
 {
   struct tty_display_info *tty = display->display_info.tty;
-  
-  turn_off_highlight (tty);
-  turn_off_insert (tty);
-  OUTPUT_IF (tty, tty->TS_end_keypad_mode);
-  OUTPUT_IF (tty, tty->TS_cursor_normal);
-  OUTPUT_IF (tty, tty->TS_end_termcap_modes);
-  OUTPUT_IF (tty, tty->TS_orig_pair);
-  /* Output raw CR so kernel can track the cursor hpos.  */
-  current_tty = tty;
-  cmputc ('\r');
+
+  if (tty->output)
+    {
+      turn_off_highlight (tty);
+      turn_off_insert (tty);
+      OUTPUT_IF (tty, tty->TS_end_keypad_mode);
+      OUTPUT_IF (tty, tty->TS_cursor_normal);
+      OUTPUT_IF (tty, tty->TS_end_termcap_modes);
+      OUTPUT_IF (tty, tty->TS_orig_pair);
+      /* Output raw CR so kernel can track the cursor hpos.  */
+      current_tty = tty;
+      cmputc ('\r');
+    }
 }
 
 void
@@ -619,9 +631,9 @@ tty_clear_end_of_line (int first_unused_hpos)
 
       for (i = curX (tty); i < first_unused_hpos; i++)
         {
-          if (TTY_TERMSCRIPT (tty))
-            fputc (' ', TTY_TERMSCRIPT (tty));
-          fputc (' ', TTY_OUTPUT (tty));
+          if (tty->termscript)
+            fputc (' ', tty->termscript);
+          fputc (' ', tty->output);
         }
       cmplus (tty, first_unused_hpos - curX (tty));
     }
@@ -807,12 +819,12 @@ tty_write_glyphs (struct glyph *string, int len)
           if (produced > 0)
             {
               fwrite (conversion_buffer, 1, produced,
-                      TTY_OUTPUT (tty));
-              if (ferror (TTY_OUTPUT (tty)))
-                clearerr (TTY_OUTPUT (tty));
-              if (TTY_TERMSCRIPT (tty))
+                      tty->output);
+              if (ferror (tty->output))
+                clearerr (tty->output);
+              if (tty->termscript)
                 fwrite (conversion_buffer, 1, produced,
-                        TTY_TERMSCRIPT (tty));
+                        tty->termscript);
             }
           len -= consumed;
           n -= consumed;
@@ -833,12 +845,12 @@ tty_write_glyphs (struct glyph *string, int len)
       if (terminal_coding.produced > 0)
         {
           fwrite (conversion_buffer, 1, terminal_coding.produced,
-                  TTY_OUTPUT (tty));
-          if (ferror (TTY_OUTPUT (tty)))
-            clearerr (TTY_OUTPUT (tty));
-          if (TTY_TERMSCRIPT (tty))
+                  tty->output);
+          if (ferror (tty->output))
+            clearerr (tty->output);
+          if (tty->termscript)
             fwrite (conversion_buffer, 1, terminal_coding.produced,
-                    TTY_TERMSCRIPT (tty));
+                    tty->termscript);
         }
     }
 
@@ -927,12 +939,12 @@ tty_insert_glyphs (struct glyph *start, int len)
       if (produced > 0)
         {
           fwrite (conversion_buffer, 1, produced,
-                  TTY_OUTPUT (tty));
-          if (ferror (TTY_OUTPUT (tty)))
-            clearerr (TTY_OUTPUT (tty));
-          if (TTY_TERMSCRIPT (tty))
+                  tty->output);
+          if (ferror (tty->output))
+            clearerr (tty->output);
+          if (tty->termscript)
             fwrite (conversion_buffer, 1, produced,
-                    TTY_TERMSCRIPT (tty));
+                    tty->termscript);
         }
 
       OUTPUT1_IF (tty, tty->TS_pad_inserted_char);
@@ -2240,7 +2252,11 @@ term_init (char *name, char *terminal_type, int must_succeed)
   
   display = get_named_tty_display (name);
   if (display)
-    return display;             /* We have already opened a display there. */
+    {
+      if (! display->display_info.tty->input)
+        error ("%s already has a suspended frame on it, can't open it twice", name);
+      return display;
+    }
 
   display = create_display ();
   tty = (struct tty_display_info *) xmalloc (sizeof (struct tty_display_info));
@@ -2550,7 +2566,7 @@ to do `unset TERMCAP' (C-shell: `unsetenv TERMCAP') as well.",
   /* Get frame size from system, or else from termcap.  */
   {
     int height, width;
-    get_tty_size (fileno (TTY_INPUT (tty)), &width, &height);
+    get_tty_size (fileno (tty->input), &width, &height);
     FrameCols (tty) = width;
     FrameRows (tty) = height;
   }
@@ -2735,7 +2751,7 @@ to do `unset TERMCAP' (C-shell: `unsetenv TERMCAP') as well.",
               && tty->TS_end_standout_mode
               && !strcmp (tty->TS_standout_mode, tty->TS_end_standout_mode));
 
-  UseTabs (tty) = tabs_safe_p (fileno (TTY_INPUT (tty))) && TabWidth (tty) == 8;
+  UseTabs (tty) = tabs_safe_p (fileno (tty->input)) && TabWidth (tty) == 8;
 
   display->scroll_region_ok
     = (tty->Wcm->cm_abs
@@ -2754,7 +2770,7 @@ to do `unset TERMCAP' (C-shell: `unsetenv TERMCAP') as well.",
 
   display->fast_clear_end_of_line = tty->TS_clr_line != 0;
 
-  init_baud_rate (fileno (TTY_INPUT (tty)));
+  init_baud_rate (fileno (tty->input));
 
 #ifdef AIXHFT
   /* The HFT system on AIX doesn't optimize for scrolling, so it's
@@ -3067,6 +3083,134 @@ delete_display (struct display *dev)
   xfree (dev);
 }
 
+
+
+DEFUN ("suspend-tty", Fsuspend_tty, Ssuspend_tty, 0, 1, 0,
+       doc: /* Suspend the terminal device TTY.
+The terminal is restored to its default state, and Emacs closes all
+access to the terminal device.  Frames that use the device are not
+deleted, but input is not read from them and if they change, their
+display is not updated.
+
+TTY may a string (a device name), a frame, or nil for the display
+device of the currently selected frame.
+
+This function runs `suspend-tty-functions' after suspending the
+device.  The functions are run with one arg, the name of the terminal
+device.
+
+`suspend-tty' does nothing if it is called on an already suspended
+device.
+
+A suspended terminal device may be resumed by calling `resume-tty' on
+it. */)
+  (tty)
+     Lisp_Object tty;
+{
+  struct display *d = get_tty_display (tty);
+  FILE *f;
+  
+  if (!d)
+    error ("Unknown tty device");
+
+  f = d->display_info.tty->input;
+  
+  if (f)
+    {
+      reset_sys_modes (d->display_info.tty);
+
+      delete_keyboard_wait_descriptor (fileno (f));
+      
+      fclose (f);
+      if (f != d->display_info.tty->output)
+        fclose (d->display_info.tty->output);
+      
+      d->display_info.tty->input = 0;
+      d->display_info.tty->output = 0;
+
+      if (FRAMEP (d->display_info.tty->top_frame))
+        FRAME_SET_VISIBLE (XFRAME (d->display_info.tty->top_frame), 0);
+      
+      /* Run `suspend-tty-functions'.  */
+      if (!NILP (Vrun_hooks))
+        {
+          Lisp_Object args[2];
+          args[0] = intern ("suspend-tty-functions");
+          if (d->display_info.tty->name)
+            {
+              args[1] = build_string (d->display_info.tty->name);
+            }
+          else
+            args[1] = Qnil;
+          Frun_hook_with_args (2, args);
+        }
+    }
+
+  return Qnil;
+}
+
+
+DEFUN ("resume-tty", Fresume_tty, Sresume_tty, 0, 1, 0,
+       doc: /* Resume the previously suspended terminal device TTY.
+The terminal is opened and reinitialized.  Frames that used the
+suspended device are revived.
+
+This function runs `resume-tty-functions' after resuming the device.
+The functions are run with one arg, the name of the terminal device.
+
+`resume-tty' does nothing if it is called on a device that is not
+suspended.
+
+TTY may a string (a device name), a frame, or nil for the display
+device of the currently selected frame. */)
+  (tty)
+     Lisp_Object tty;
+{
+  struct display *d = get_tty_display (tty);
+  int fd;
+
+  if (!d)
+    error ("Unknown tty device");
+
+  if (!d->display_info.tty->input)
+    {
+      fd = emacs_open (d->display_info.tty->name, O_RDWR | O_NOCTTY, 0);
+  
+#ifdef TIOCNOTTY
+      /* Drop our controlling tty if it is the same device. */
+      if (ioctl (fd, TIOCNOTTY, 0) != -1)
+        {
+          no_controlling_tty = 1;
+        }
+#endif
+
+      d->display_info.tty->output = fdopen (fd, "w+");
+      d->display_info.tty->input = d->display_info.tty->output;
+    
+      add_keyboard_wait_descriptor (fd);
+
+      if (FRAMEP (d->display_info.tty->top_frame))
+        FRAME_SET_VISIBLE (XFRAME (d->display_info.tty->top_frame), 1);
+
+      init_sys_modes (d->display_info.tty);
+
+      /* Run `suspend-tty-functions'.  */
+      if (!NILP (Vrun_hooks))
+        {
+          Lisp_Object args[2];
+          args[0] = intern ("resume-tty-functions");
+          if (d->display_info.tty->name)
+            {
+              args[1] = build_string (d->display_info.tty->name);
+            }
+          else
+            args[1] = Qnil;
+          Frun_hook_with_args (2, args);
+        }
+    }
+
+  return Qnil;
+}
 
 
 void
@@ -3092,6 +3236,20 @@ The functions are run with one argument, the name of the tty to be deleted.
 See `delete-tty'.  */);
   Vdelete_tty_after_functions = Qnil;
 
+
+  DEFVAR_LISP ("suspend-tty-functions", &Vsuspend_tty_functions,
+    doc: /* Functions to be run after suspending a tty.
+The functions are run with one argument, the name of the tty to be suspended.
+See `suspend-tty'.  */);
+  Vsuspend_tty_functions = Qnil;
+
+
+  DEFVAR_LISP ("resume-tty-functions", &Vresume_tty_functions,
+    doc: /* Functions to be run after resuming a tty.
+The functions are run with one argument, the name of the tty that was revived.
+See `resume-tty'.  */);
+  Vresume_tty_functions = Qnil;
+
   Qframe_tty_name = intern ("frame-tty-name");
   staticpro (&Qframe_tty_name);
 
@@ -3103,6 +3261,8 @@ See `delete-tty'.  */);
   defsubr (&Sframe_tty_name);
   defsubr (&Sframe_tty_type);
   defsubr (&Sdelete_tty);
+  defsubr (&Ssuspend_tty);
+  defsubr (&Sresume_tty);
 
   Fprovide (intern ("multi-tty"), Qnil);
 
diff --git a/src/termchar.h b/src/termchar.h
index fbf91f2458f..3053061c1b7 100644
--- a/src/termchar.h
+++ b/src/termchar.h
@@ -42,8 +42,10 @@ struct tty_display_info
   
   /* Input/output */
   
-  FILE *input;                  /* The stream to be used for terminal input. */
-  FILE *output;                 /* The stream to be used for terminal output. */
+  FILE *input;                  /* The stream to be used for terminal input.
+                                   NULL if the terminal is suspended. */
+  FILE *output;                 /* The stream to be used for terminal output.
+                                   NULL if the terminal is suspended. */
   
   FILE *termscript;             /* If nonzero, send all terminal output
                                    characters to this stream also.  */
@@ -200,9 +202,5 @@ extern struct tty_display_info *tty_list;
 
 #define CURTTY() FRAME_TTY (SELECTED_FRAME())
 
-#define TTY_INPUT(t) ((t)->input)
-#define TTY_OUTPUT(t) ((t)->output)
-#define TTY_TERMSCRIPT(t) ((t)->termscript)
-
 /* arch-tag: bf9f0d49-842b-42fb-9348-ec8759b27193
    (do not change this comment) */
diff --git a/src/termhooks.h b/src/termhooks.h
index c79e77379b1..6b2b0d07867 100644
--- a/src/termhooks.h
+++ b/src/termhooks.h
@@ -513,7 +513,6 @@ struct display
      frames on the display when it calls this hook, so infinite
      recursion is prevented.  */
   void (*delete_display_hook) P_ ((struct display *));
-
 };