[Qemu-devel] [PATCH 16/17] 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 for
such terminals.

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

 migration.c |    6 +++++-
 monitor.c   |   50 +++++++++++++++++++++++++++++++++++++++-----------
 monitor.h   |    1 +
 qemu-char.c |    2 +-
 vl.c        |    2 +-
 5 files changed, 47 insertions(+), 14 deletions(-)

diff --git a/migration.c b/migration.c
index 18c1492..c9365d7 100644
--- a/migration.c
+++ b/migration.c
@@ -128,7 +128,11 @@ void do_info_migrate(void)
 void migrate_fd_monitor_suspend(FdMigrationState *s)
 {
     s->mon_resume_handle = monitor_suspend();
-    dprintf("suspending monitor\n");
+    if (s->mon_resume_handle)
+        dprintf("suspending monitor\n");
+    else
+        monitor_printf("terminal does not allow synchronous migration, "
+                       "continuing detached\n");
 }
 
 void migrate_fd_error(FdMigrationState *s)
diff --git a/monitor.c b/monitor.c
index 2306b10..364b13d 100644
--- a/monitor.c
+++ b/monitor.c
@@ -95,10 +95,16 @@ static void monitor_read_command(MonitorTerm *term, int 
show_prompt)
         readline_show_prompt(term->rs);
 }
 
-static void monitor_read_password(ReadLineFunc *readline_func, void *opaque)
+static int monitor_read_password(ReadLineFunc *readline_func, void *opaque)
 {
-    readline_start(cur_term->rs, "Password: ", 1, readline_func, opaque);
-    /* prompt is printed on return from the command handler */
+    if (cur_term->rs) {
+        readline_start(cur_term->rs, "Password: ", 1, readline_func, opaque);
+        /* prompt is printed on return from the command handler */
+        return 0;
+    } else {
+        monitor_printf("terminal does not support password prompting\n");
+        return -ENOTTY;
+    }
 }
 
 void monitor_flush(void)
@@ -385,6 +391,9 @@ static void do_info_history (void)
     int i;
     const char *str;
 
+    if (!cur_term->rs)
+        return;
+
     i = 0;
     for(;;) {
         str = readline_get_history(cur_term->rs, i);
@@ -2833,8 +2842,15 @@ static void term_read(void *opaque, const uint8_t *buf, 
int size)
 
     cur_term = opaque;
 
-    for (i = 0; i < size; i++)
-        readline_handle_byte(cur_term->rs, buf[i]);
+    if (cur_term->rs) {
+        for (i = 0; i < size; i++)
+            readline_handle_byte(cur_term->rs, buf[i]);
+    } else {
+        if (size == 0 || buf[size - 1] != 0)
+            monitor_printf("corrupted command\n");
+        else
+            monitor_handle_command((char *)buf);
+    }
 
     cur_term = old_term;
 }
@@ -2848,6 +2864,9 @@ static void monitor_command_cb(void *opaque, const char 
*cmdline)
 
 void *monitor_suspend(void)
 {
+    if (!cur_term->rs)
+        return NULL;
+
     cur_term->suspend_cnt++;
     return cur_term;
 }
@@ -2858,8 +2877,10 @@ void monitor_resume(void *handle)
 
     cur_term = handle;
 
-    if (--cur_term->suspend_cnt == 0)
-        readline_show_prompt(cur_term->rs);
+    if (cur_term->rs) {
+        if (--cur_term->suspend_cnt == 0)
+            readline_show_prompt(cur_term->rs);
+    }
 
     cur_term = old_term;
 }
@@ -2907,10 +2928,12 @@ void monitor_init(CharDriverState *chr, int flags)
     term = qemu_mallocz(sizeof(*term));
 
     term->chr = chr;
-    term->flags = flags;
+    term->flags = flags & (MONITOR_IS_DEFAULT | MONITOR_USE_READLINE);
     term->suspend_cnt = 1; /* resume on reset */
-    term->rs = readline_init(monitor_find_completion);
-    monitor_read_command(term, 0);
+    if (flags & MONITOR_USE_READLINE) {
+        term->rs = readline_init(monitor_find_completion);
+        monitor_read_command(term, 0);
+    }
 
     qemu_chr_add_handlers(chr, term_can_read, term_read, term_event, term);
 
@@ -2938,6 +2961,8 @@ void monitor_read_bdrv_key_start(BlockDriverState *bs,
                                  BlockDriverCompletionFunc *completion_cb,
                                  void *opaque)
 {
+    int err;
+
     if (!bdrv_key_required(bs)) {
         if (completion_cb)
             completion_cb(opaque, 0);
@@ -2950,5 +2975,8 @@ void monitor_read_bdrv_key_start(BlockDriverState *bs,
     cur_term->password_completion_cb = completion_cb;
     cur_term->password_opaque = opaque;
 
-    monitor_read_password(bdrv_password_cb, bs);
+    err = monitor_read_password(bdrv_password_cb, bs);
+
+    if (err && completion_cb)
+        completion_cb(opaque, err);
 }
diff --git a/monitor.h b/monitor.h
index 7af267d..bb2a06a 100644
--- a/monitor.h
+++ b/monitor.h
@@ -6,6 +6,7 @@
 
 /* flags for monitor_init */
 #define MONITOR_IS_DEFAULT    0x01
+#define MONITOR_USE_READLINE  0x02
 
 void monitor_init(CharDriverState *chr, int flags);
 void *monitor_suspend(void);
diff --git a/qemu-char.c b/qemu-char.c
index d107c53..b7480a0 100644
--- a/qemu-char.c
+++ b/qemu-char.c
@@ -2102,7 +2102,7 @@ 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 a80a25b..d569e6b 100644
--- a/vl.c
+++ b/vl.c
@@ -5594,7 +5594,7 @@ int main(int argc, char **argv, char **envp)
     text_consoles_set_display(display_state);
 
     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];