ps2: fix sending of PAUSE/BREAK scancodes

The processing of the scancodes for PAUSE/BREAK  has been broken since
the conversion to qcodes in:

  commit 8c10e0baf0
  Author: Hervé Poussineau <hpoussin@reactos.org>
  Date:   Thu Sep 15 22:06:26 2016 +0200

    ps2: use QEMU qcodes instead of scancodes

When using a VNC client, with the raw scancode extension, the client
will send a scancode of 0xc6 for both PAUSE and BREAK. There is mistakenly
no entry in the qcode_to_number table for this scancode, so
ps2_keyboard_event() just generates a log message and discards the
scancode

When using a SPICE client, it will also send 0xc6 for BREAK, but
will send 0xe1 0x1d 0x45 0xe1 0x9d 0xc5 for PAUSE. There is no
entry in the qcode_to_number table for the scancode 0xe1 because
it is a special XT keyboard prefix not mapping to any QKeyCode.
Again ps2_keyboard_event() just generates a log message and discards
the scancode. The following 0x1d, 0x45, 0x9d, 0xc5 scancodes get
handled correctly. Rather than trying to handle 3 byte sequences
of scancodes in the PS/2 driver, special case the SPICE input
code so that it captures the 3 byte pause sequence and turns it
into a Pause QKeyCode.

Signed-off-by: Daniel P. Berrange <berrange@redhat.com>
Message-id: 20170727113243.23991-1-berrange@redhat.com
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

ui/input-keymap.c

@@ -233,6 +233,7 @@ static const int qcode_to_number[] = {
     [Q_KEY_CODE_KP_ENTER] = 0x9c,
     [Q_KEY_CODE_KP_DECIMAL] = 0x53,
     [Q_KEY_CODE_SYSRQ] = 0x54,
+    [Q_KEY_CODE_PAUSE] = 0xc6,
 
     [Q_KEY_CODE_KP_0] = 0x52,
     [Q_KEY_CODE_KP_1] = 0x4f,

ui/keymaps.h

@@ -59,6 +59,7 @@ typedef struct {
 /* "grey" keys will usually need a 0xe0 prefix */
 #define SCANCODE_GREY   0x80
 #define SCANCODE_EMUL0  0xE0
+#define SCANCODE_EMUL1  0xE1
 /* "up" flag */
 #define SCANCODE_UP     0x80
 

ui/spice-input.c

@@ -32,6 +32,7 @@ typedef struct QemuSpiceKbd {
     SpiceKbdInstance sin;
     int ledstate;
     bool emul0;
+    size_t pauseseq;
 } QemuSpiceKbd;
 
 static void kbd_push_key(SpiceKbdInstance *sin, uint8_t frag);
@@ -64,6 +65,25 @@ static void kbd_push_key(SpiceKbdInstance *sin, uint8_t scancode)
         keycode |= SCANCODE_GREY;
     }
 
+    if (scancode == SCANCODE_EMUL1) {
+        kbd->pauseseq++;
+        return;
+    } else if (kbd->pauseseq == 1) {
+        if (keycode == 0x1d) {
+            kbd->pauseseq++;
+            return;
+        } else {
+            kbd->pauseseq = 0;
+        }
+    } else if (kbd->pauseseq == 2) {
+        if (keycode == 0x45) {
+            qemu_input_event_send_key_qcode(NULL, Q_KEY_CODE_PAUSE, !up);
+            kbd->pauseseq = 0;
+            return;
+        }
+        kbd->pauseseq = 0;
+    }
+
     qemu_input_event_send_key_number(NULL, keycode, !up);
 }