[PATCH V2] qemu,qmp: add keydown and keyup command for qmp

[Lai Jiangshan <laijs@cn.fujitsu.com>]

sendkey is a very good command for human using it in their monitor,
but it is not a good idea to port it to qmp, because qmp is a machine
protocol. So we introduce keydown and keyup command for qmp, they
simulate the events that keyboard send to the system.

Example, simulates ctrl+alt+f1:
{ "execute": "keydown", "arguments": { "keycode": 29 } }  #press down ctrl
{ "execute": "keydown", "arguments": { "keycode": 56 } }  #press down alt
{ "execute": "keydown", "arguments": { "keycode": 59 } }  #press down f1
{ "execute": "keyup", "arguments": { "keycode": 59 } }    #release f1
{ "execute": "keyup", "arguments": { "keycode": 56 } }    #release alt
{ "execute": "keyup", "arguments": { "keycode": 29 } }    #release ctrl

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
---
diff --git a/monitor.c b/monitor.c
index 22ae3bb..725df83 100644
--- a/monitor.c
+++ b/monitor.c
@@ -1810,16 +1810,25 @@ static uint8_t keycodes[MAX_KEYCODES];
 static int nb_pending_keycodes;
 static QEMUTimer *key_timer;
 
-static void release_keys(void *opaque)
+static void keydown(uint8_t keycode)
 {
-    int keycode;
+    if (keycode & 0x80)
+        kbd_put_keycode(0xe0);
+    kbd_put_keycode(keycode & 0x7f);
+}
 
+static void keyup(uint8_t keycode)
+{
+    if (keycode & 0x80)
+        kbd_put_keycode(0xe0);
+    kbd_put_keycode(keycode | 0x80);
+}
+
+static void release_keys(void *opaque)
+{
     while (nb_pending_keycodes > 0) {
         nb_pending_keycodes--;
-        keycode = keycodes[nb_pending_keycodes];
-        if (keycode & 0x80)
-            kbd_put_keycode(0xe0);
-        kbd_put_keycode(keycode | 0x80);
+        keyup(keycodes[nb_pending_keycodes]);
     }
 }
 
@@ -1866,17 +1875,41 @@ static void do_sendkey(Monitor *mon, const QDict *qdict)
     }
     nb_pending_keycodes = i;
     /* key down events */
-    for (i = 0; i < nb_pending_keycodes; i++) {
-        keycode = keycodes[i];
-        if (keycode & 0x80)
-            kbd_put_keycode(0xe0);
-        kbd_put_keycode(keycode & 0x7f);
-    }
+    for (i = 0; i < nb_pending_keycodes; i++)
+        keydown(keycodes[i]);
     /* delayed key up events */
     qemu_mod_timer(key_timer, qemu_get_clock(vm_clock) +
                    muldiv64(get_ticks_per_sec(), hold_time, 1000));
 }
 
+static int qmp_keyaction(const QDict *qdict, int down)
+{
+    int keycode = qdict_get_int(qdict, "keycode");
+
+    if (keycode < 0 || keycode >= 256) {
+        qerror_report(QERR_INVALID_PARAMETER_VALUE, "keycode",
+                      "a valid keycode");
+        return -1;
+    }
+
+    if (down)
+        keydown(keycode);
+    else
+        keyup(keycode);
+
+    return 0;
+}
+
+static int qmp_keydown(Monitor *mon, const QDict *qdict, QObject **ret_data)
+{
+    return qmp_keyaction(qdict, 1);
+}
+
+static int qmp_keyup(Monitor *mon, const QDict *qdict, QObject **ret_data)
+{
+    return qmp_keyaction(qdict, 0);
+}
+
 static int mouse_button_state;
 
 static void do_mouse_move(Monitor *mon, const QDict *qdict)
diff --git a/qmp-commands.hx b/qmp-commands.hx
index df40a3d..4c449bb 100644
--- a/qmp-commands.hx
+++ b/qmp-commands.hx
@@ -338,6 +338,58 @@ Example:
 EQMP
 
     {
+        .name       = "keydown",
+        .args_type  = "keycode:i",
+        .params     = "keycode",
+        .help       = "press down a key",
+        .user_print = monitor_user_noop,
+        .mhandler.cmd_new = qmp_keydown,
+    },
+
+SQMP
+keydown
+---
+
+Press down a key.
+
+Arguments:
+
+- "keycode": the code of the key to press down (json-int)
+
+Example:
+
+-> { "execute": "keydown", "arguments": { "keycode": 16 } }
+<- { "return": {} }
+
+EQMP
+
+    {
+        .name       = "keyup",
+        .args_type  = "keycode:i",
+        .params     = "keycode",
+        .help       = "release a key",
+        .user_print = monitor_user_noop,
+        .mhandler.cmd_new = qmp_keyup,
+    },
+
+SQMP
+keyup
+---
+
+Release a key.
+
+Arguments:
+
+- "keycode": the code of the key to release (json-int)
+
+Example:
+
+-> { "execute": "keyup", "arguments": { "keycode": 16 } }
+<- { "return": {} }
+
+EQMP
+
+    {
         .name       = "cpu",
         .args_type  = "index:i",
         .params     = "index",