[2/2] curses: add option to specify VGA font encoding

diff --git a/configure b/configure
index 9979ca708d..1270dc8dc0 100755
--- a/configure
+++ b/configure
@@ -3449,14 +3449,17 @@  if test "$curses" != "no" ; then
 #include <locale.h>
 #include <curses.h>
 #include <wchar.h>
+#include <langinfo.h>
 int main(void) {
+  const char *codeset;
   wchar_t wch = L'w';
   setlocale(LC_ALL, "");
   resize_term(0, 0);
   addwstr(L"wide chars\n");
   addnwstr(&wch, 1);
   add_wch(WACS_DEGREE);
-  return 0;
+  codeset = nl_langinfo(CODESET);
+  return codeset != 0;
 }
 EOF
   IFS=:
diff --git a/qapi/ui.json b/qapi/ui.json
index c5d1d7f099..12d3a2c751 100644
--- a/qapi/ui.json
+++ b/qapi/ui.json
@@ -1131,6 +1131,7 @@ 
 # @full-screen:   Start user interface in fullscreen mode (default: off).
 # @window-close:  Allow to quit qemu with window close button (default: on).
 # @gl:            Enable OpenGL support (default: off).
+# @charset:       Font charset used by guest (default: CP437).
 #
 # Since: 2.12
 #
@@ -1139,7 +1140,8 @@ 
   'base'    : { 'type'           : 'DisplayType',
                 '*full-screen'   : 'bool',
                 '*window-close'  : 'bool',
-                '*gl'            : 'DisplayGLMode' },
+                '*gl'            : 'DisplayGLMode',
+                '*charset'       : 'str' },
   'discriminator' : 'type',
   'data'    : { 'gtk'            : 'DisplayGTK',
                 'egl-headless'   : 'DisplayEGLHeadless'} }
diff --git a/qemu-options.hx b/qemu-options.hx
index 1cf9aac1fe..4bc4e736bb 100644
--- a/qemu-options.hx
+++ b/qemu-options.hx
@@ -1216,7 +1216,7 @@  DEF("display", HAS_ARG, QEMU_OPTION_display,
     "            [,window_close=on|off][,gl=on|core|es|off]\n"
     "-display gtk[,grab_on_hover=on|off][,gl=on|off]|\n"
     "-display vnc=<display>[,<optargs>]\n"
-    "-display curses\n"
+    "-display curses[,charset=<encoding>]\n"
     "-display none\n"
     "-display egl-headless[,rendernode=<file>]"
     "                select display type\n"
@@ -1248,6 +1248,9 @@  support a text mode, QEMU can display this output using a
 curses/ncurses interface. Nothing is displayed when the graphics
 device is in graphical mode or if the graphics device does not support
 a text mode. Generally only the VGA device models support text mode.
+The font charset used by the guest can be specified with the
+@code{charset} option, for example @code{charset=CP850} for IBM CP850
+encoding. The default is @code{CP437}.
 @item none
 Do not display video output. The guest will still see an emulated
 graphics card, but its output will not be displayed to the QEMU
diff --git a/ui/curses.c b/ui/curses.c
index 1724dd57d4..203cc075d0 100644
--- a/ui/curses.c
+++ b/ui/curses.c
@@ -27,6 +27,10 @@ 
 #include <sys/ioctl.h>
 #include <termios.h>
 #endif
+#include <locale.h>
+#include <wchar.h>
+#include <langinfo.h>
+#include <iconv.h>
 
 #include "qapi/error.h"
 #include "qemu-common.h"
@@ -54,7 +58,8 @@  static WINDOW *screenpad = NULL;
 static int width, height, gwidth, gheight, invalidate;
 static int px, py, sminx, sminy, smaxx, smaxy;
 
-static chtype vga_to_curses[256];
+static const char *font_charset = "CP437";
+static cchar_t vga_to_curses[256];
 
 static wint_t console_getch(enum maybe_keycode *maybe_keycode)
 {
@@ -77,19 +82,23 @@  static void curses_update(DisplayChangeListener *dcl,
                           int x, int y, int w, int h)
 {
     console_ch_t *line;
-    chtype curses_line[width];
+    cchar_t curses_line[width];
 
     line = screen + y * width;
     for (h += y; y < h; y ++, line += width) {
         for (x = 0; x < width; x++) {
             chtype ch = line[x] & 0xff;
             chtype at = line[x] & ~0xff;
-            if (vga_to_curses[ch]) {
-                ch = vga_to_curses[ch];
+            if (vga_to_curses[ch].chars[0]) {
+                curses_line[x] = vga_to_curses[ch];
+            } else {
+                curses_line[x].chars[0] = ch;
+                curses_line[x].chars[1] = 0;
+                curses_line[x].attr = 0;
             }
-            curses_line[x] = ch | at;
+            curses_line[x].attr |=  at;
         }
-        mvwaddchnstr(screenpad, y, 0, curses_line, width);
+        mvwadd_wchnstr(screenpad, y, 0, curses_line, width);
     }
 
     pnoutrefresh(screenpad, py, px, sminy, sminx, smaxy - 1, smaxx - 1);
@@ -391,6 +400,254 @@  static void curses_atexit(void)
     endwin();
 }
 
+/* Setup wchar glyph for one UCS-2 char */
+static void convert_ucs(int glyph, uint16_t ch, iconv_t conv)
+{
+    wchar_t wch;
+    char *pch, *pwch;
+    size_t sch, swch;
+
+    pch = (char *) &ch;
+    pwch = (char *) &wch;
+    sch = sizeof(ch);
+    swch = sizeof(wch);
+
+    if (iconv(conv, &pch, &sch, &pwch, &swch) == (size_t) -1) {
+        fprintf(stderr, "Could not convert 0x%04x from UCS-2 to WCHAR_T: %s\n",
+                        ch, strerror(errno));
+    } else {
+        vga_to_curses[glyph].chars[0] = wch;
+    }
+}
+
+/* Setup wchar glyph for one font character */
+static void convert_font(unsigned char ch, iconv_t conv)
+{
+    wchar_t wch;
+    char *pch, *pwch;
+    size_t sch, swch;
+
+    pch = (char *) &ch;
+    pwch = (char *) &wch;
+    sch = sizeof(ch);
+    swch = sizeof(wch);
+
+    if (iconv(conv, &pch, &sch, &pwch, &swch) == (size_t) -1) {
+        fprintf(stderr, "Could not convert 0x%02x from %s to WCHAR_T: %s\n",
+                        ch, font_charset, strerror(errno));
+    } else {
+        vga_to_curses[ch].chars[0] = wch;
+    }
+}
+
+/* Convert one wchar to UCS-2 */
+static uint16_t get_ucs(wchar_t wch, iconv_t conv)
+{
+    uint16_t ch;
+    char *pch, *pwch;
+    size_t sch, swch;
+
+    pch = (char *) &ch;
+    pwch = (char *) &wch;
+    sch = sizeof(ch);
+    swch = sizeof(wch);
+
+    if (iconv(conv, &pwch, &swch, &pch, &sch) == (size_t) -1) {
+        fprintf(stderr, "Could not convert 0x%02x from WCHAR_T to UCS-2: %s\n",
+                        wch, strerror(errno));
+        return 0xFFFD;
+    }
+
+    return ch;
+}
+
+/*
+ * Setup mapping for vga to curses line graphics.
+ */
+static void font_setup(void)
+{
+    /*
+     * Control characters are normally non-printable, but VGA does have
+     * well-known glyphs for them.
+     */
+    static uint16_t control_characters[0x20] = {
+      0x0020,
+      0x263a,
+      0x263b,
+      0x2665,
+      0x2666,
+      0x2663,
+      0x2660,
+      0x2022,
+      0x25d8,
+      0x25cb,
+      0x25d9,
+      0x2642,
+      0x2640,
+      0x266a,
+      0x266b,
+      0x263c,
+      0x25ba,
+      0x25c4,
+      0x2195,
+      0x203c,
+      0x00b6,
+      0x00a7,
+      0x25ac,
+      0x21a8,
+      0x2191,
+      0x2193,
+      0x2192,
+      0x2190,
+      0x221f,
+      0x2194,
+      0x25b2,
+      0x25bc
+    };
+
+    iconv_t ucs_to_wchar_conv;
+    iconv_t wchar_to_ucs_conv;
+    iconv_t font_conv;
+    int i;
+
+    ucs_to_wchar_conv = iconv_open("WCHAR_T", "UCS-2");
+    if (ucs_to_wchar_conv == (iconv_t) -1) {
+        fprintf(stderr, "Could not convert font glyphs from UCS-2: '%s'\n",
+                        strerror(errno));
+        exit(1);
+    }
+
+    wchar_to_ucs_conv = iconv_open("UCS-2", "WCHAR_T");
+    if (wchar_to_ucs_conv == (iconv_t) -1) {
+        fprintf(stderr, "Could not convert font glyphs to UCS-2: '%s'\n",
+                        strerror(errno));
+        exit(1);
+    }
+
+    font_conv = iconv_open("WCHAR_T", font_charset);
+    if (font_conv == (iconv_t) -1) {
+        fprintf(stderr, "Could not convert font glyphs from %s: '%s'\n",
+                        font_charset, strerror(errno));
+        exit(1);
+    }
+
+    /* Control characters */
+    for (i = 0; i <= 0x1F; i++) {
+        convert_ucs(i, control_characters[i], ucs_to_wchar_conv);
+    }
+
+    for (i = 0x20; i <= 0xFF; i++) {
+        convert_font(i, font_conv);
+    }
+
+    /* DEL */
+    convert_ucs(0x7F, 0x2302, ucs_to_wchar_conv);
+
+    if (strcmp(nl_langinfo(CODESET), "UTF-8")) {
+        /* Non-Unicode capable, use termcap equivalents for those available */
+        for (i = 0; i <= 0xFF; i++) {
+            switch (get_ucs(vga_to_curses[i].chars[0], wchar_to_ucs_conv)) {
+            case 0x00a3:
+                vga_to_curses[i] = *WACS_STERLING;
+                break;
+            case 0x2591:
+                vga_to_curses[i] = *WACS_BOARD;
+                break;
+            case 0x2592:
+                vga_to_curses[i] = *WACS_CKBOARD;
+                break;
+            case 0x2502:
+                vga_to_curses[i] = *WACS_VLINE;
+                break;
+            case 0x2524:
+                vga_to_curses[i] = *WACS_RTEE;
+                break;
+            case 0x2510:
+                vga_to_curses[i] = *WACS_URCORNER;
+                break;
+            case 0x2514:
+                vga_to_curses[i] = *WACS_LLCORNER;
+                break;
+            case 0x2534:
+                vga_to_curses[i] = *WACS_BTEE;
+                break;
+            case 0x252c:
+                vga_to_curses[i] = *WACS_TTEE;
+                break;
+            case 0x251c:
+                vga_to_curses[i] = *WACS_LTEE;
+                break;
+            case 0x2500:
+                vga_to_curses[i] = *WACS_HLINE;
+                break;
+            case 0x253c:
+                vga_to_curses[i] = *WACS_PLUS;
+                break;
+            case 0x256c:
+                vga_to_curses[i] = *WACS_LANTERN;
+                break;
+            case 0x256a:
+                vga_to_curses[i] = *WACS_NEQUAL;
+                break;
+            case 0x2518:
+                vga_to_curses[i] = *WACS_LRCORNER;
+                break;
+            case 0x250c:
+                vga_to_curses[i] = *WACS_ULCORNER;
+                break;
+            case 0x2588:
+                vga_to_curses[i] = *WACS_BLOCK;
+                break;
+            case 0x03c0:
+                vga_to_curses[i] = *WACS_PI;
+                break;
+            case 0x00b1:
+                vga_to_curses[i] = *WACS_PLMINUS;
+                break;
+            case 0x2265:
+                vga_to_curses[i] = *WACS_GEQUAL;
+                break;
+            case 0x2264:
+                vga_to_curses[i] = *WACS_LEQUAL;
+                break;
+            case 0x00b0:
+                vga_to_curses[i] = *WACS_DEGREE;
+                break;
+            case 0x25a0:
+                vga_to_curses[i] = *WACS_BULLET;
+                break;
+            case 0x2666:
+                vga_to_curses[i] = *WACS_DIAMOND;
+                break;
+            case 0x2192:
+                vga_to_curses[i] = *WACS_RARROW;
+                break;
+            case 0x2190:
+                vga_to_curses[i] = *WACS_LARROW;
+                break;
+            case 0x2191:
+                vga_to_curses[i] = *WACS_UARROW;
+                break;
+            case 0x2193:
+                vga_to_curses[i] = *WACS_DARROW;
+                break;
+            case 0x23ba:
+                vga_to_curses[i] = *WACS_S1;
+                break;
+            case 0x23bb:
+                vga_to_curses[i] = *WACS_S3;
+                break;
+            case 0x23bc:
+                vga_to_curses[i] = *WACS_S7;
+                break;
+            case 0x23bd:
+                vga_to_curses[i] = *WACS_S9;
+                break;
+            }
+        }
+    }
+}
+
 static void curses_setup(void)
 {
     int i, colour_default[8] = {
@@ -419,47 +676,7 @@  static void curses_setup(void)
         init_pair(i, COLOR_WHITE, COLOR_BLACK);
     }
 
-    /*
-     * Setup mapping for vga to curses line graphics.
-     * FIXME: for better font, have to use ncursesw and setlocale()
-     */
-#if 0
-    /* FIXME: map from where? */
-    ACS_S1;
-    ACS_S3;
-    ACS_S7;
-    ACS_S9;
-#endif
-    /* ACS_* is not constant. So, we can't initialize statically. */
-    vga_to_curses['\0'] = ' ';
-    vga_to_curses[0x04] = ACS_DIAMOND;
-    vga_to_curses[0x18] = ACS_UARROW;
-    vga_to_curses[0x19] = ACS_DARROW;
-    vga_to_curses[0x1a] = ACS_RARROW;
-    vga_to_curses[0x1b] = ACS_LARROW;
-    vga_to_curses[0x9c] = ACS_STERLING;
-    vga_to_curses[0xb0] = ACS_BOARD;
-    vga_to_curses[0xb1] = ACS_CKBOARD;
-    vga_to_curses[0xb3] = ACS_VLINE;
-    vga_to_curses[0xb4] = ACS_RTEE;
-    vga_to_curses[0xbf] = ACS_URCORNER;
-    vga_to_curses[0xc0] = ACS_LLCORNER;
-    vga_to_curses[0xc1] = ACS_BTEE;
-    vga_to_curses[0xc2] = ACS_TTEE;
-    vga_to_curses[0xc3] = ACS_LTEE;
-    vga_to_curses[0xc4] = ACS_HLINE;
-    vga_to_curses[0xc5] = ACS_PLUS;
-    vga_to_curses[0xce] = ACS_LANTERN;
-    vga_to_curses[0xd8] = ACS_NEQUAL;
-    vga_to_curses[0xd9] = ACS_LRCORNER;
-    vga_to_curses[0xda] = ACS_ULCORNER;
-    vga_to_curses[0xdb] = ACS_BLOCK;
-    vga_to_curses[0xe3] = ACS_PI;
-    vga_to_curses[0xf1] = ACS_PLMINUS;
-    vga_to_curses[0xf2] = ACS_GEQUAL;
-    vga_to_curses[0xf3] = ACS_LEQUAL;
-    vga_to_curses[0xf8] = ACS_DEGREE;
-    vga_to_curses[0xfe] = ACS_BULLET;
+    font_setup();
 }
 
 static void curses_keyboard_setup(void)
@@ -492,6 +709,10 @@  static void curses_display_init(DisplayState *ds, DisplayOptions *opts)
     }
 #endif
 
+    setlocale(LC_CTYPE, "");
+    if (opts->charset) {
+        font_charset = opts->charset;
+    }
     curses_setup();
     curses_keyboard_setup();
     atexit(curses_atexit);