[Qemu-devel] [PATCH v2 17/19] monitor: Improve mux'ed console experience

[Jan Kiszka]

Up to now, you never really knew if you already switched the console
after pressing CTRL-A C or if you mistyped it again. This patch
clarifies the situation by providing a prompt in a new line and
injecting a linebreak when switching away again. For this purpose, the
two events CHR_EVENT_MUX_IN and CHR_EVENT_MUX_OUT are introduced and
distributed on focus switches.

Signed-off-by: Jan Kiszka <address@hidden>
---

 monitor.c   |   27 ++++++++++++++++++++++-----
 qemu-char.c |   11 +++++++++--
 qemu-char.h |    8 +++++---
 readline.c  |    5 +++++
 readline.h  |    1 +
 5 files changed, 42 insertions(+), 10 deletions(-)

diff --git a/monitor.c b/monitor.c
index ba0e9a8..7cae863 100644
--- a/monitor.c
+++ b/monitor.c
@@ -2887,12 +2887,27 @@ static void monitor_event(void *opaque, int event)
 {
     Monitor *mon = opaque;
 
-    if (event != CHR_EVENT_RESET)
-       return;
+    switch (event) {
+    case CHR_EVENT_MUX_IN:
+        readline_restart(mon->rs);
+        monitor_resume(mon);
+        monitor_flush(mon);
+        break;
+
+    case CHR_EVENT_MUX_OUT:
+        if (mon->suspend_cnt == 0)
+            monitor_printf(mon, "\n");
+        monitor_flush(mon);
+        monitor_suspend(mon);
+        break;
 
-    monitor_printf(mon, "QEMU %s monitor - type 'help' for more information\n",
-                   QEMU_VERSION);
-    readline_show_prompt(mon->rs);
+    case CHR_EVENT_RESET:
+        monitor_printf(mon, "QEMU %s monitor - type 'help' for more "
+                       "information\n", QEMU_VERSION);
+        if (mon->chr->focus == 0)
+            readline_show_prompt(mon->rs);
+        break;
+    }
 }
 
 void monitor_init(CharDriverState *chr, int flags)
@@ -2909,6 +2924,8 @@ void monitor_init(CharDriverState *chr, int flags)
 
     mon->chr = chr;
     mon->flags = flags;
+    if (mon->chr->focus != 0)
+        mon->suspend_cnt = 1; /* mux'ed monitors start suspended */
     mon->rs = readline_init(mon, monitor_find_completion);
     monitor_read_command(mon, 0);
 
diff --git a/qemu-char.c b/qemu-char.c
index f815646..8c5544c 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -310,6 +310,12 @@ static void mux_print_help(CharDriverState *chr)
     }
 }
 
+static void mux_chr_send_event(MuxDriver *d, int mux_nr, int event)
+{
+    if (d->chr_event[mux_nr])
+        d->chr_event[mux_nr](d->ext_opaque[mux_nr], event);
+}
+
 static int mux_proc_byte(CharDriverState *chr, MuxDriver *d, int ch)
 {
     if (d->term_got_escape) {
@@ -341,9 +347,11 @@ static int mux_proc_byte(CharDriverState *chr, MuxDriver 
*d, int ch)
             break;
         case 'c':
             /* Switch to the next registered device */
+            mux_chr_send_event(d, chr->focus, CHR_EVENT_MUX_OUT);
             chr->focus++;
             if (chr->focus >= d->mux_cnt)
                 chr->focus = 0;
+            mux_chr_send_event(d, chr->focus, CHR_EVENT_MUX_IN);
             break;
        case 't':
            term_timestamps = !term_timestamps;
@@ -413,8 +421,7 @@ static void mux_chr_event(void *opaque, int event)
 
     /* Send the event to all registered listeners */
     for (i = 0; i < d->mux_cnt; i++)
-        if (d->chr_event[i])
-            d->chr_event[i](d->ext_opaque[i], event);
+        mux_chr_send_event(d, i, event);
 }
 
 static void mux_chr_update_read_handler(CharDriverState *chr)
diff --git a/qemu-char.h b/qemu-char.h
index e5ad45c..e1aa8db 100644
--- a/qemu-char.h
+++ b/qemu-char.h
@@ -6,9 +6,11 @@
 
 /* character device */
 
-#define CHR_EVENT_BREAK 0 /* serial break char */
-#define CHR_EVENT_FOCUS 1 /* focus to this terminal (modal input needed) */
-#define CHR_EVENT_RESET 2 /* new connection established */
+#define CHR_EVENT_BREAK   0 /* serial break char */
+#define CHR_EVENT_FOCUS   1 /* focus to this terminal (modal input needed) */
+#define CHR_EVENT_RESET   2 /* new connection established */
+#define CHR_EVENT_MUX_IN  3 /* mux-focus was set to this terminal */
+#define CHR_EVENT_MUX_OUT 4 /* mux-focus will move on */
 
 
 #define CHR_IOCTL_SERIAL_SET_PARAMS   1
diff --git a/readline.c b/readline.c
index 1868b10..9c4b68b 100644
--- a/readline.c
+++ b/readline.c
@@ -444,6 +444,11 @@ void readline_start(ReadLineState *rs, const char *prompt, 
int read_password,
     rs->readline_func = readline_func;
     rs->readline_opaque = opaque;
     rs->read_password = read_password;
+    readline_restart(rs);
+}
+
+void readline_restart(ReadLineState *rs)
+{
     rs->cmd_buf_index = 0;
     rs->cmd_buf_size = 0;
 }
diff --git a/readline.h b/readline.h
index fcf0f33..fc9806e 100644
--- a/readline.h
+++ b/readline.h
@@ -46,6 +46,7 @@ void readline_handle_byte(ReadLineState *rs, int ch);
 
 void readline_start(ReadLineState *rs, const char *prompt, int read_password,
                     ReadLineFunc *readline_func, void *opaque);
+void readline_restart(ReadLineState *rs);
 void readline_show_prompt(ReadLineState *rs);
 
 ReadLineState *readline_init(Monitor *mon,