2002-06-04 Marcus Brinkmann <marcus@gnu.org>

	* display.h: New file.
	* display.c: Likewise.

3 files changed, 864 insertions, 0 deletions

diff --git a/console/ChangeLog b/console/ChangeLog
index 5b228dd6..4e14a145 100644
--- a/console/ChangeLog
+++ b/console/ChangeLog
@@ -1,5 +1,10 @@
 2002-06-04  Marcus Brinkmann  <marcus@gnu.org>
 
+	* display.h: New file.
+	* display.c: Likewise.
+
+2002-06-04  Marcus Brinkmann  <marcus@gnu.org>
+
 	* display.h: Renamed to ...
 	* display-drv.h: ... this.
 	* Makefile (LCLHDRS): Rename display.h to display-drv.h.
diff --git a/console/display.c b/console/display.c
new file mode 100644
index 00000000..363c9c09
--- /dev/null
+++ b/console/display.c
@@ -0,0 +1,825 @@
+/* display.c - The display component of a virtual console.
+   Copyright (C) 2002 Free Software Foundation, Inc.
+   Written by Marcus Brinkmann and Kalle Olavi Niemitalo.
+
+   This file is part of the GNU Hurd.
+
+   The GNU Hurd 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.
+
+   The GNU Hurd 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., 59 Temple Place - Suite 330, Boston, MA  02111, USA. */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <unistd.h>
+#include <wchar.h>
+#include <iconv.h>
+#include <argp.h>
+#include <string.h>
+
+#include <sys/io.h>
+#include <sys/mman.h>
+#include <sys/fcntl.h>
+#include <cthreads.h>
+
+#ifndef __STDC_ISO_10646__
+#error It is required that wchar_t is UCS-4.
+#endif
+
+#include "display.h"
+
+
+struct screen
+{
+  /* A screen matrix, including the scroll back buffer.  */
+  wchar_t *matrix;
+
+  /* The size of the screen, in lines.  */
+  int lines;
+
+  /* The top most line of the screen in the video buffer.  */
+  int current_line;
+
+  /* Maximum number of lines scrolled back.  */
+  int scrolling_max;
+
+  int width;
+  int height;
+};
+typedef struct screen *screen_t;
+
+struct parse
+{
+  /* The parsing state of output characters, needed to handle escape
+     character sequences.  */
+  enum
+    {
+      STATE_NORMAL = 0,
+      /* An escape character has just been parsed.  */
+      STATE_ESC,
+      STATE_ESC_BRACKET_INIT,
+      STATE_ESC_BRACKET,
+      STATE_ESC_BRACKET_QUESTION
+    } state;
+
+  /* How many parameters an escape sequence may have.  */
+#define PARSE_MAX_PARAMS 10
+  int params[PARSE_MAX_PARAMS];
+  int nparams;
+};
+
+struct cursor
+{
+  /* The visibility of the cursor.  */
+  int status;
+#define CURSOR_INVISIBLE 1
+#define CURSOR_STANDOUT 2
+
+  size_t x;
+  size_t y;
+  size_t saved_x;
+  size_t saved_y;
+};
+
+struct display
+{
+  /* The lock for the virtual console display structure.  */
+  struct mutex lock;
+
+  /* The state of the conversion of output characters.  */
+  iconv_t cd;
+
+  struct parse parse;
+  struct screen screen;
+  struct cursor cursor;
+
+  struct
+  {
+    /* Current attribute.  */
+    char current;
+    int fg;
+    int bg;
+    int def_fg;
+    int def_bg;
+    int reverse : 1;
+    int bold : 1;
+    int blink : 1;
+    int invisible : 1;
+    int dim : 1;
+    int underline : 1;
+  } attr;
+
+  /* Indicates if OWNER_ID is initialized.  */
+  int has_owner;
+  /* Specifies the ID of the process that should receive the WINCH
+     signal for this virtual console.  */
+  int owner_id;
+};
+
+
+static error_t
+screen_init (screen_t screen)
+{
+  screen->width = 80;
+  screen->height = 25;
+  screen->lines = 200;	/* XXX For now.  */
+  screen->current_line = 0;
+  screen->matrix = calloc (screen->lines * screen->width, sizeof (wchar_t));
+  if (!screen->matrix)
+    return ENOMEM;
+
+  wmemset (screen->matrix, L' ', screen->height * screen->width);
+  /* XXX Set attribute flags.  */
+  return 0;
+}
+
+static void
+screen_deinit (screen_t screen)
+{
+  free (screen->matrix);
+}
+
+static void
+screen_fill (screen_t screen, size_t x, size_t y, size_t w, size_t h,
+	     wchar_t chr, char attr)
+{
+  wchar_t *matrixp = screen->matrix + y * screen->width + x;
+
+  while (h--)
+    {
+      /* XXX Set attribute flags.  */
+      wmemset (matrixp, L' ', w);
+      matrixp += screen->width;
+    }
+
+  /* XXX Flag screen change, but here?  */
+}
+
+static void
+screen_scroll_up (screen_t screen, size_t x, size_t y, size_t w, size_t h,
+		  int amt, wchar_t chr, char attr)
+{
+  wchar_t *matrixp = screen->matrix + y * screen->width + x;
+
+  if (amt < 0)
+    return;
+
+  while (h-- > amt)
+    {
+      wmemcpy (matrixp, matrixp + amt * screen->width, w);
+      matrixp += screen->width;
+    }
+  screen_fill (screen, x, y, w, h, chr, attr);
+}
+
+static void
+screen_scroll_down (screen_t screen, size_t x, size_t y, size_t w, size_t h,
+		    int amt, wchar_t chr, char attr)
+{
+  wchar_t *matrixp = screen->matrix + (y + h - 1) * screen->width + x;
+
+  if (amt < 0)
+    return;
+
+  while (h-- > amt)
+    {
+      wmemcpy (matrixp, matrixp - amt * screen->width, w);
+      matrixp -= screen->width;
+    }
+  screen_fill (screen, x, y, w, h, chr, attr);
+}
+
+static void
+screen_scroll_left (screen_t screen, size_t x, size_t y, size_t w, size_t h,
+		    int amt, wchar_t chr, char attr)
+{
+  int y;
+  wchar_t *matrixp = screen->matrix + y * screen->width + x;
+
+  if (amt < 0)
+    return;
+  if (amt > w)
+    amt = w;
+
+  for (y = 0; y < y + h; y++)
+    {
+      wmemmov (matrixp, matrixp + amt, w - amt);
+      matrixp += screen->width;
+    }
+  screen_fill (screen, x + w - amt, y, amt, h, chr, attr);
+}
+
+static void
+screen_scroll_right (screen_t screen, size_t x, size_t y, size_t w, size_t h,
+		     int amt, wchar_t chr, char attr)
+{
+  int y;
+  wchar_t *matrixp = screen->matrix + y * screen->width + x;
+
+  if (amt < 0)
+    return;
+  if (amt > w)
+    amt = w;
+
+  for (y = 0; y < y + h; y++)
+    {
+      wmemmov (matrixp + amt, matrixp, w - amt);
+      matrixp += screen->width;
+    }
+  screen_fill (screen, x, y, amt, h, chr, attr);
+}
+
+
+/* Create a new virtual console display, with the system encoding
+   being ENCODING.  */
+error_t
+display_create (display_t *r_display, const char *encoding)
+{
+  error_t err = 0;
+  display_t display;
+
+  *r_display = NULL;
+  display = calloc (1, sizeof *display);
+  if (!display)
+    return ENOMEM;
+
+  mutex_init (&display->lock);
+  err = screen_init (&display->screen);
+  if (err)
+    {
+      free (display);
+      return err;
+    }
+
+  /* WCHAR_T happens to be UCS-4 on the GNU system.  */
+  display->cd = iconv_open ("WCHAR_T", encoding);
+  if (display->cd == (iconv_t) -1)
+    {
+      err = errno;
+      screen_deinit (&display->screen);
+      free (display);
+    }
+  *r_display = display;
+  return err;
+}
+
+
+/* Destroy the display DISPLAY.  */
+void
+display_destroy (display_t display)
+{
+  iconv_close (display->cd);
+  screen_deinit (&display->screen);
+  free (display);
+}
+
+
+static void
+handle_esc_bracket_hl (display_t display, int code, int flag)
+{
+  switch (code)
+    {
+    case 34:
+      /* Cursor standout: <cnorm>, <cvvis>.  */
+      if (flag)
+	display->cursor.status |= CURSOR_STANDOUT;
+      else
+	display->cursor.status &= ~CURSOR_STANDOUT;
+      /* XXX Flag cursor status change.  */
+      break;
+    }
+}
+
+static void
+handle_esc_bracket_m (display_t display, int code)
+{
+  switch (code)
+    {
+    case 0:
+      /* All attributes off: <sgr0>.  */
+      display->attr.fg = display->attr.def_fg;
+      display->attr.bg = display->attr.def_bg;
+      display->attr.reverse = display->attr.bold = display->attr.blink
+	= display->attr.invisible = display->attr.dim
+	= display->attr.underline = 0;
+      /* Cursor attributes aren't text attributes.  */
+      break;
+    case 1:
+      /* Bold on: <bold>.  */
+      display->attr.bold = 1;
+      break;
+    case 2:
+      /* Dim on: <dim>.  */
+      display->attr.dim = 1;
+      break;
+    case 4:
+      /* Underline on: <smul>.  */
+      display->attr.underline = 1;
+      break;
+    case 5:
+      /* Blink on: <blink>.  */
+      display->attr.blink = 1;
+      break;
+    case 7:
+      /* Reverse video on: <rev>, <smso>.  */
+      display->attr.reverse = 1;
+      break;
+    case 8:
+      /* Concealed on: <invis>.  */
+      display->attr.invisible = 1;
+      break;
+    case 21:
+      /* Bold Off.  */
+      display->attr.bold = 0;
+      break;
+    case 22:
+      /* Dim off.  */
+      display->attr.dim = 0;
+      break;
+    case 24:
+      /* Underline off: <rmul>.  */
+      display->attr.underline = 0;
+      break;
+    case 25:
+      /* Blink off.  */
+      display->attr.blink = 0;
+      break;
+    case 27:
+      /* Reverse video off: <rmso>.  */
+      display->attr.reverse = 0;
+      break;
+    case 28:
+      /* Concealed off.  */
+      display->attr.invisible = 0;
+      break;
+    case 30 ... 37:
+      /* Set foreground color: <setaf>.  */
+      display->attr.fg = code - 30;
+      break;
+    case 39:
+      /* Default foreground color; ANSI?.  */
+      display->attr.fg = display->attr.def_fg;
+      break;
+    case 40 ... 47:
+      /* Set background color: <setab>.  */
+      display->attr.bg = code - 40;
+      break;
+    case 49:
+      /* Default background color; ANSI?.  */
+      display->attr.bg = display->attr.def_bg;
+      break;
+    }
+  /* XXX */
+  /* recalc_attr (display); */
+}
+
+static void
+handle_esc_bracket (display_t display, char op)
+{
+  int i;
+
+  static void limit_cursor (void)
+    {
+      if (display->cursor.x >= display->screen.width)
+	display->cursor.x = display->screen.width - 1;
+      else if (display->cursor.x < 0)
+	display->cursor.x = 0;
+      
+      if (display->cursor.y >= display->screen.height)
+	display->cursor.y = display->screen.height - 1;
+      else if (display->cursor.y < 0)
+	display->cursor.y = 0;
+
+      /* XXX Flag cursor change.  */
+    }
+
+  switch (op)
+    {
+    case 'H':
+    case 'f':
+      /* Cursor position: <cup>.  */
+      display->cursor.x = display->parse.params[1] - 1;
+      display->cursor.y = display->parse.params[0] - 1;
+      limit_cursor ();
+      break;
+    case 'G':
+      /* Horizontal position: <hpa>.  */
+      display->cursor.x = display->parse.params[0] - 1;
+      limit_cursor ();
+      break;
+    case 'F':
+      /* Beginning of previous line.  */
+      display->cursor.x = 0;
+      /* fall through */
+    case 'A':
+      /* Cursor up: <cuu>, <cuu1>.  */
+      display->cursor.y -= (display->parse.params[0] ?: 1);
+      limit_cursor ();
+      break;
+    case 'E':
+      /* Beginning of next line.  */
+      display->cursor.x = 0;
+      /* Fall through.  */
+    case 'B':
+      /* Cursor down: <cud1>, <cud>.  */
+      display->cursor.y += (display->parse.params[0] ?: 1);
+      limit_cursor ();
+      break;
+    case 'C':
+      /* Cursor right: <cuf1>, <cuf>.  */
+      display->cursor.x += (display->parse.params[0] ?: 1);
+      limit_cursor ();
+      break;
+    case 'D':
+      /* Cursor left: <cub>, <cub1>.  */
+      display->cursor.x -= (display->parse.params[0] ?: 1);
+      limit_cursor ();
+      break;
+    case 's':
+      /* Save cursor position: <sc>.  */
+      display->cursor.saved_x = display->cursor.x;
+      display->cursor.saved_y = display->cursor.y;
+      break;
+    case 'u':
+      /* Restore cursor position: <rc>.  */
+      display->cursor.x = display->cursor.saved_x;
+      display->cursor.y = display->cursor.saved_y;
+      /* In case the screen was larger before:  */
+      limit_cursor ();
+      break;
+    case 'h':
+      /* Reset mode.  */
+      for (i = 0; i < display->parse.nparams; i++)
+	handle_esc_bracket_hl (display, display->parse.params[i], 0);
+      break;
+    case 'l':
+      /* Set mode.  */
+      for (i = 0; i < display->parse.nparams; i++)
+	handle_esc_bracket_hl (display, display->parse.params[i], 1);
+      break;
+    case 'm':
+      for (i = 0; i < display->parse.nparams; i++)
+	handle_esc_bracket_m (display, display->parse.params[i]);
+      break;
+    case 'J':
+      switch (display->parse.params[0])
+	{
+	case 0:
+	  /* Clear to end of screen: <ed>.  */
+	  screen_fill (&display->screen, display->cursor.x, display->cursor.y,
+		       display->screen.width - display->cursor.x, 1, L' ',
+		       display->attr.current);
+	  screen_fill (&display->screen, 0, display->cursor.y + 1,
+		       display->screen.width,
+		       display->screen.height - display->cursor.y,
+			L' ', display->attr.current);
+	  break;
+	case 1:
+	  /* Clear to beginning of screen.  */
+	  screen_fill (&display->screen, 0, 0,
+		       display->screen.width, display->cursor.y,
+		       L' ', display->attr.current);
+	  screen_fill (&display->screen, 0, display->cursor.y,
+		       display->cursor.x + 1, 1,
+		       L' ', display->attr.current);
+	  break;
+	case 2:
+	  /* Clear entire screen.  */
+	  screen_fill (&display->screen, 0, 0,
+		       display->screen.width, display->screen.height,
+		       L' ', display->attr.current);
+	  break;
+	}
+      break;
+    case 'K':
+      switch (display->parse.params[0])
+	{
+	case 0:
+	  /* Clear to end of line: <el>.  */
+	  screen_fill (&display->screen, display->cursor.x, display->cursor.y,
+		       display->screen.width - display->cursor.x, 1,
+		       L' ', display->attr.current);
+	  break;
+	case 1:
+	  /* Clear to beginning of line: <el1>.  */
+	  screen_fill (&display->screen, 0, display->cursor.y,
+		       display->cursor.x + 1, 1,
+		       L' ', display->attr.current);
+	  break;
+	case 2:
+	  /* Clear entire line.  */
+	  screen_fill (&display->screen, 0, display->cursor.y,
+		       display->screen.width, 1,
+		       L' ', display->attr.current);
+	  break;
+	}
+      break;
+    case 'L':
+      /* Insert line(s): <il1>, <il>.  */
+      screen_scroll_down (&display->screen, 0, display->cursor.y,
+			  display->screen.width,
+			  display->screen.height - display->cursor.y,
+			  display->parse.params[0] ?: 1,
+			  L' ', display->attr.current);
+      break;
+    case 'M':
+      /* Delete line(s): <dl1>, <dl>.  */
+      screen_scroll_up (&display->screen, 0, display->cursor.y,
+			display->screen.width,
+			display->screen.height - display->cursor.y,
+			display->parse.params[0] ?: 1,
+			L' ', display->attr.current);
+      break;
+    case '@':
+      /* Insert character(s): <ich1>, <ich>.  */
+      screen_scroll_right (&display->screen, display->cursor.x,
+			   display->cursor.y,
+			   display->screen.width - display->cursor.x, 1,
+			   display->parse.params[0] ?: 1,
+			   L' ', display->attr.current);
+      break;
+    case 'P':
+      /* Delete character(s): <dch1>, <dch>.  */
+      screen_scroll_left (&display->screen, display->cursor.x,
+			  display->cursor.y,
+			  display->screen.width - display->cursor.x, 1,
+			  display->parse.params[0] ?: 1,
+			  L' ', display->attr.current);
+      break;
+    case 'S':
+      /* Scroll up: <ind>, <indn>.  */
+      screen_scroll_up (&display->screen, 0, 0,
+			display->screen.width, display->screen.height,
+			display->parse.params[0] ?: 1,
+			L' ', display->attr.current);
+      break;
+    case 'T':
+      /* Scroll down: <ri>, <rin>.  */
+      screen_scroll_down (&display->screen, 0, 0,
+			  display->screen.width, display->screen.height,
+			  display->parse.params[0] ?: 1,
+			  L' ', display->attr.current);
+      break;
+    case 'X':
+      /* Erase character(s): <ech>.  */
+      screen_fill (&display->screen, display->cursor.x, display->cursor.y,
+		   display->parse.params[0] ?: 1, 1,
+		   L' ', display->attr.current);
+      break;
+    }
+}
+
+static void
+handle_esc_bracket_question_hl (display_t display, int code, int flag)
+{
+  switch (code)
+    {
+    case 25:
+      /* Cursor invisibility: <civis>, <cnorm>.  */
+      if (flag)
+	display->cursor.status |= CURSOR_INVISIBLE;
+      else
+	display->cursor.status &= ~CURSOR_INVISIBLE;
+      /* XXX Flag cursor status change.  */
+      break;
+    }
+}
+
+
+static void
+handle_esc_bracket_question (display_t display, char op)
+{
+  int i;
+  switch (op)
+    {
+    case 'h':
+      /* Reset mode.  */
+      for (i = 0; i < display->parse.nparams; ++i)
+	handle_esc_bracket_question_hl (display, display->parse.params[i], 0);
+      break;
+    case 'l':
+      /* Set mode.  */
+      for (i = 0; i < display->parse.nparams; ++i)
+	handle_esc_bracket_question_hl (display, display->parse.params[i], 1);
+      break;
+    }
+}
+
+/* Display must be locked.  */
+static void
+display_output_one (display_t display, wchar_t chr)
+{
+  void newline (void)
+    {
+      if (display->cursor.y < display->screen.height - 1)
+	{
+	  display->cursor.y++;
+	  /* XXX Flag cursor update.  */
+	}
+      else
+	{
+	  if (display->screen.current_line == display->screen.lines - 1)
+	    display->screen.current_line = 0;
+	  else
+	    display->screen.current_line++;
+	  /* XXX Set attribute flags.  */
+	  screen_fill (&display->screen, 0, display->screen.height - 1,
+		       display->screen.width, 1, L' ', display->screen.width);
+	  if (display->screen.scrolling_max <
+	      display->screen.lines - display->screen.height)
+	    display->screen.scrolling_max++;
+	  /* XXX Flag current line change.  */
+	  /* XXX Flag change of last line.  */
+	  /* XXX Possibly flag change of length of scroll back buffer.  */
+	}
+    }
+
+  switch (display->parse.state)
+    {
+    case STATE_NORMAL:
+      switch (chr)
+	{
+	case L'\r':
+	  /* Carriage return: <cr>.  */
+	  if (display->cursor.x)
+	    {
+	      display->cursor.x = 0;
+	      /* XXX Flag cursor update.  */
+	    }
+	  break;
+	case L'\n':
+	  /* Cursor down: <cud1>, scroll up: <ind>.  */
+	  newline ();
+	  break;
+	case L'\b':
+	  /* Cursor backward: <cub1>.  */
+	  if (display->cursor.x > 0 || display->cursor.y > 0)
+	    {
+	      if (display->cursor.x > 0)
+		display->cursor.x--;
+	      else
+		{
+		  /* XXX This implements the <bw> functionality.
+		     The alternative is to cut off and set x to 0.  */
+		  display->cursor.x = display->screen.width - 1;
+		  display->cursor.y--;
+		}
+	      /* XXX Flag cursor update.  */
+	    }
+	  break;
+	case L'\t':
+	  /* Horizontal tab: <ht> */
+	  display->cursor.x = (display->cursor.x | 7) + 1;
+	  if (display->cursor.x >= display->screen.width)
+	    {
+	      display->cursor.x = 0;
+	      newline ();
+	    }
+	  /* XXX Flag cursor update.  */
+	  break;
+	case L'\033':
+	  display->parse.state = STATE_ESC;
+	  break;
+	case L'\0':
+	  /* Padding character: <pad>.  */
+	  break;
+	default:
+	  {
+	    int line = (display->screen.current_line + display->cursor.y)
+	      % display->screen.lines;
+
+	    /* XXX Set attribute flags.  */
+	    display->screen.matrix[line * display->screen.width
+				   + display->cursor.x] = chr;
+
+	    display->cursor.x++;
+	    if (display->cursor.x == display->screen.height)
+	      {
+		display->cursor.x = 0;
+		newline ();
+	      }
+	  }
+	  break;
+	}
+      break;
+
+    case STATE_ESC:
+      switch (chr)
+	{
+	case L'[':
+	  display->parse.state = STATE_ESC_BRACKET_INIT;
+	  break;
+	case L'c':
+	  /* Clear screen and home cursor: <clear>.  */
+	  screen_fill (&display->screen, 0, 0,
+		       display->screen.width, display->screen.height,
+		       L' ', display->attr.current);
+	  display->cursor.x = display->cursor.y = 0;
+	  /* XXX Flag cursor change.  */
+	  display->parse.state = STATE_NORMAL;
+	  break;
+	default:
+	  /* Unsupported escape sequence.  */
+	  display->parse.state = STATE_NORMAL;
+	  break;
+	}
+      break;
+      
+    case STATE_ESC_BRACKET_INIT:
+      memset (&display->parse.params, 0, sizeof display->parse.params);
+      display->parse.nparams = 0;
+      if (chr == '?')
+	{
+	  display->parse.state = STATE_ESC_BRACKET_QUESTION;
+	  break;	/* Consume the question mark.  */
+	}
+      else
+	display->parse.state = STATE_ESC_BRACKET;
+      /* Fall through.  */
+    case STATE_ESC_BRACKET:
+    case STATE_ESC_BRACKET_QUESTION:
+      if (chr >= '0' && chr <= '9')
+	display->parse.params[display->parse.nparams]
+	    = display->parse.params[display->parse.nparams]*10 + chr - '0';
+      else if (chr == ';')
+	{
+	  if (++(display->parse.nparams) >= PARSE_MAX_PARAMS)
+	    display->parse.state = STATE_NORMAL; /* too many */
+	}
+      else
+	{
+	  display->parse.nparams++;
+	  if (display->parse.state == STATE_ESC_BRACKET)
+	    handle_esc_bracket (display, chr);
+	  else
+	    handle_esc_bracket_question (display, chr);
+	  display->parse.state = STATE_NORMAL;
+	}
+      break;
+    default:
+      abort ();
+    }
+}
+
+
+/* Output LENGTH bytes starting from BUFFER in the system encoding.
+   Set BUFFER and LENGTH to the new values.  The exact semantics are
+   just as in the iconv interface.  */
+error_t
+display_output (display_t display, char **buffer, size_t *length)
+{
+#define CONV_OUTBUF_SIZE 256
+  error_t err = 0;
+
+  mutex_lock (&display->lock);
+  while (!err && *length > 0)
+    {
+      size_t nconv;
+      wchar_t outbuf[CONV_OUTBUF_SIZE];
+      char *outptr = (char *) outbuf;
+      size_t outsize = CONV_OUTBUF_SIZE;
+      error_t saved_err;
+      int i;
+
+      nconv = iconv (display->cd, buffer, length, &outptr, &outsize);
+      saved_err = errno;
+
+      /* First process all successfully converted characters.  */
+      for (i = 0; i < CONV_OUTBUF_SIZE - outsize; i++)
+	display_output_one (display, outbuf[i]);
+
+      if (nconv == (size_t) -1)
+	{
+	  /* Conversion didn't work out.  */
+	  if (saved_err == EINVAL)
+	    /* This is only an unfinished byte sequence at the end of
+	       the input buffer.  */
+	    break;
+	  else if (saved_err != E2BIG)
+	    err = saved_err;
+	}
+    }
+  mutex_unlock (&display->lock);
+  return err;
+}
+
+
+void
+display_getsize (display_t display, struct winsize *winsize)
+{
+  mutex_lock (&display->lock);
+  winsize->ws_row = display->screen.height;
+  winsize->ws_col = display->screen.width;
+  winsize->ws_xpixel = 0;
+  winsize->ws_ypixel = 0;
+  mutex_unlock (&display->lock);
+}
diff --git a/console/display.h b/console/display.h
new file mode 100644
index 00000000..0043fb3e
--- /dev/null
+++ b/console/display.h
@@ -0,0 +1,34 @@
+/* display.h - Interface to the display component of a virtual console.
+   Copyright (C) 2002 Free Software Foundation, Inc.
+   Written by Marcus Brinkmann.
+
+   This file is part of the GNU Hurd.
+
+   The GNU Hurd 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.
+
+   The GNU Hurd 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., 59 Temple Place - Suite 330, Boston, MA  02111, USA. */
+
+#ifndef DISPLAY_H
+#define DISPLAY_H
+
+#include <sys/ioctl.h>
+
+struct display;
+typedef struct display *display_t;
+
+error_t display_create (display_t *r_display, const char *encoding);
+void display_destroy (display_t display);
+error_t display_output (display_t display, char **buffer, size_t *length);
+void display_getsize (display_t display, struct winsize *winsize);
+
+#endif	/* DISPLAY_H */