[Qemu-devel] [PATCH v2 18/19] monitor: Introduce MONITOR_USE_READLINE flag

[Jan Kiszka]

This allows to create monitor terminals that do not make use of the
interactive readline back-end but rather send complete commands. The
pass-through monitor interface of the gdbstub will be an example.

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

 migration.c |    7 +++++--
 monitor.c   |   47 +++++++++++++++++++++++++++++++++++++----------
 monitor.h   |    3 ++-
 qemu-char.c |    2 +-
 vl.c        |    2 +-
 5 files changed, 46 insertions(+), 15 deletions(-)

diff --git a/migration.c b/migration.c
index 15639c1..b3904b2 100644
--- a/migration.c
+++ b/migration.c
@@ -128,8 +128,11 @@ void do_info_migrate(Monitor *mon)
 void migrate_fd_monitor_suspend(FdMigrationState *s)
 {
     s->mon_resume = cur_mon;
-    monitor_suspend(cur_mon);
-    dprintf("suspending monitor\n");
+    if (monitor_suspend(cur_mon) == 0)
+        dprintf("suspending monitor\n");
+    else
+        monitor_printf(cur_mon, "terminal does not allow synchronous "
+                       "migration, continuing detached\n");
 }
 
 void migrate_fd_error(FdMigrationState *s)
diff --git a/monitor.c b/monitor.c
index 7cae863..a7f1cc1 100644
--- a/monitor.c
+++ b/monitor.c
@@ -97,11 +97,17 @@ static void monitor_read_command(Monitor *mon, int 
show_prompt)
         readline_show_prompt(mon->rs);
 }
 
-static void monitor_read_password(Monitor *mon, ReadLineFunc *readline_func,
-                                  void *opaque)
+static int monitor_read_password(Monitor *mon, ReadLineFunc *readline_func,
+                                 void *opaque)
 {
-    readline_start(mon->rs, "Password: ", 1, readline_func, opaque);
-    /* prompt is printed on return from the command handler */
+    if (mon->rs) {
+        readline_start(mon->rs, "Password: ", 1, readline_func, opaque);
+        /* prompt is printed on return from the command handler */
+        return 0;
+    } else {
+        monitor_printf(mon, "terminal does not support password prompting\n");
+        return -ENOTTY;
+    }
 }
 
 void monitor_flush(Monitor *mon)
@@ -373,6 +379,8 @@ static void do_info_history(Monitor *mon)
     int i;
     const char *str;
 
+    if (!mon->rs)
+        return;
     i = 0;
     for(;;) {
         str = readline_get_history(mon->rs, i);
@@ -2859,8 +2867,15 @@ static void monitor_read(void *opaque, const uint8_t 
*buf, int size)
 
     cur_mon = opaque;
 
-    for (i = 0; i < size; i++)
-        readline_handle_byte(cur_mon->rs, buf[i]);
+    if (cur_mon->rs) {
+        for (i = 0; i < size; i++)
+            readline_handle_byte(cur_mon->rs, buf[i]);
+    } else {
+        if (size == 0 || buf[size - 1] != 0)
+            monitor_printf(cur_mon, "corrupted command\n");
+        else
+            monitor_handle_command(cur_mon, (char *)buf);
+    }
 
     cur_mon = old_mon;
 }
@@ -2872,13 +2887,18 @@ static void monitor_command_cb(Monitor *mon, const char 
*cmdline, void *opaque)
     monitor_resume(mon);
 }
 
-void monitor_suspend(Monitor *mon)
+int monitor_suspend(Monitor *mon)
 {
+    if (!mon->rs)
+        return -ENOTTY;
     mon->suspend_cnt++;
+    return 0;
 }
 
 void monitor_resume(Monitor *mon)
 {
+    if (!mon->rs)
+        return;
     if (--mon->suspend_cnt == 0)
         readline_show_prompt(mon->rs);
 }
@@ -2926,8 +2946,10 @@ void monitor_init(CharDriverState *chr, int flags)
     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);
+    if (flags & MONITOR_USE_READLINE) {
+        mon->rs = readline_init(mon, monitor_find_completion);
+        monitor_read_command(mon, 0);
+    }
 
     qemu_chr_add_handlers(chr, monitor_can_read, monitor_read, monitor_event,
                           mon);
@@ -2956,6 +2978,8 @@ void monitor_read_bdrv_key_start(Monitor *mon, 
BlockDriverState *bs,
                                  BlockDriverCompletionFunc *completion_cb,
                                  void *opaque)
 {
+    int err;
+
     if (!bdrv_key_required(bs)) {
         if (completion_cb)
             completion_cb(opaque, 0);
@@ -2968,5 +2992,8 @@ void monitor_read_bdrv_key_start(Monitor *mon, 
BlockDriverState *bs,
     mon->password_completion_cb = completion_cb;
     mon->password_opaque = opaque;
 
-    monitor_read_password(mon, bdrv_password_cb, bs);
+    err = monitor_read_password(mon, bdrv_password_cb, bs);
+
+    if (err && completion_cb)
+        completion_cb(opaque, err);
 }
diff --git a/monitor.h b/monitor.h
index 95a4060..13e8cc7 100644
--- a/monitor.h
+++ b/monitor.h
@@ -9,10 +9,11 @@ extern Monitor *cur_mon;
 
 /* flags for monitor_init */
 #define MONITOR_IS_DEFAULT    0x01
+#define MONITOR_USE_READLINE  0x02
 
 void monitor_init(CharDriverState *chr, int flags);
 
-void monitor_suspend(Monitor *mon);
+int monitor_suspend(Monitor *mon);
 void monitor_resume(Monitor *mon);
 
 void monitor_read_bdrv_key_start(Monitor *mon, BlockDriverState *bs,
diff --git a/qemu-char.c b/qemu-char.c
index 8c5544c..26e8825 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -2130,7 +2130,7 @@ CharDriverState *qemu_chr_open(const char *label, const 
char *filename, void (*i
         chr = qemu_chr_open(label, p, NULL);
         if (chr) {
             chr = qemu_chr_open_mux(chr);
-            monitor_init(chr, 0);
+            monitor_init(chr, MONITOR_USE_READLINE);
         } else {
             printf("Unable to open driver: %s\n", p);
         }
diff --git a/vl.c b/vl.c
index 4c2a448..0b55051 100644
--- a/vl.c
+++ b/vl.c
@@ -5658,7 +5658,7 @@ int main(int argc, char **argv, char **envp)
     qemu_chr_initial_reset();
 
     if (monitor_device && monitor_hd)
-        monitor_init(monitor_hd, MONITOR_IS_DEFAULT);
+        monitor_init(monitor_hd, MONITOR_USE_READLINE | MONITOR_IS_DEFAULT);
 
     for(i = 0; i < MAX_SERIAL_PORTS; i++) {
         const char *devname = serial_devices[i];