[PATCH 6/6] virtio-console: notify the guest about terminal resizes

[Szymon Lukasz <noh4hss@gmail.com>]

If a virtio serial port is a console port forward terminal resize
messages from the chardev backend to the guest.

Signed-off-by: Szymon Lukasz <noh4hss@gmail.com>
---
 hw/char/virtio-console.c | 64 +++++++++++++++++++++++++++++++++++++---
 1 file changed, 60 insertions(+), 4 deletions(-)

diff --git a/hw/char/virtio-console.c b/hw/char/virtio-console.c
index 97b9240ef5..1ea06aad08 100644
--- a/hw/char/virtio-console.c
+++ b/hw/char/virtio-console.c
@@ -29,6 +29,7 @@ typedef struct VirtConsole {
 
     CharBackend chr;
     guint watch;
+    uint16_t cols, rows;
 } VirtConsole;
 
 /*
@@ -104,6 +105,36 @@ static ssize_t flush_buf(VirtIOSerialPort *port,
     return ret;
 }
 
+static void virtconsole_send_resize(VirtIOSerialPort *port)
+{
+    uint16_t cols, rows;
+    VirtConsole *vcon = VIRTIO_CONSOLE(port);
+
+    /*
+     * We probably shouldn't send these messages before
+     * we told the guest it is a console port (which we do
+     * by sending VIRTIO_CONSOLE_CONSOLE_PORT message).
+     * Instead of adding a new field to the device state
+     * lets just use the guest_connected field for that purpose
+     * since the guest should not care about the terminal size
+     * before opening the port.
+     */
+    if (!port->guest_connected) {
+        return;
+    }
+
+    if (qemu_chr_fe_get_winsize(&vcon->chr, &cols, &rows) < 0) {
+        cols = 0;
+        rows = 0;
+    }
+
+    if (cols != vcon->cols || rows != vcon->rows) {
+        vcon->cols = cols;
+        vcon->rows = rows;
+        virtio_serial_send_console_resize(port, cols, rows);
+    }
+}
+
 /* Callback function that's called when the guest opens/closes the port */
 static void set_guest_connected(VirtIOSerialPort *port, int guest_connected)
 {
@@ -111,7 +142,9 @@ static void set_guest_connected(VirtIOSerialPort *port, int guest_connected)
     DeviceState *dev = DEVICE(port);
     VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(port);
 
-    if (!k->is_console) {
+    if (k->is_console) {
+        virtconsole_send_resize(port);
+    } else {
         qemu_chr_fe_set_open(&vcon->chr, guest_connected);
     }
 
@@ -171,6 +204,22 @@ static void chr_event(void *opaque, QEMUChrEvent event)
     }
 }
 
+static void chr_event_console(void *opaque, QEMUChrEvent event)
+{
+    VirtConsole *vcon = opaque;
+    VirtIOSerialPort *port = VIRTIO_SERIAL_PORT(vcon);
+
+    switch (event) {
+    case CHR_EVENT_OPENED:
+    case CHR_EVENT_RESIZE:
+        trace_virtio_console_chr_event(port->id, event);
+        virtconsole_send_resize(port);
+        break;
+    default:
+        break;
+    }
+}
+
 static int chr_be_change(void *opaque)
 {
     VirtConsole *vcon = opaque;
@@ -179,7 +228,9 @@ static int chr_be_change(void *opaque)
 
     if (k->is_console) {
         qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read,
-                                 NULL, chr_be_change, vcon, NULL, true);
+                                 chr_event_console, chr_be_change,
+                                 vcon, NULL, true);
+        virtconsole_send_resize(port);
     } else {
         qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read,
                                  chr_event, chr_be_change, vcon, NULL, false);
@@ -207,7 +258,7 @@ static void virtconsole_enable_backend(VirtIOSerialPort *port, bool enable)
         VirtIOSerialPortClass *k = VIRTIO_SERIAL_PORT_GET_CLASS(port);
 
         qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read,
-                                 k->is_console ? NULL : chr_event,
+                                 k->is_console ? chr_event_console : chr_event,
                                  chr_be_change, vcon, NULL, false);
     } else {
         qemu_chr_fe_set_handlers(&vcon->chr, NULL, NULL, NULL,
@@ -227,6 +278,11 @@ static void virtconsole_realize(DeviceState *dev, Error **errp)
         return;
     }
 
+    if (k->is_console) {
+        vcon->cols = (uint16_t) -1;
+        vcon->rows = (uint16_t) -1;
+    }
+
     if (qemu_chr_fe_backend_connected(&vcon->chr)) {
         /*
          * For consoles we don't block guest data transfer just
@@ -239,7 +295,7 @@ static void virtconsole_realize(DeviceState *dev, Error **errp)
          */
         if (k->is_console) {
             qemu_chr_fe_set_handlers(&vcon->chr, chr_can_read, chr_read,
-                                     NULL, chr_be_change,
+                                     chr_event_console, chr_be_change,
                                      vcon, NULL, true);
             virtio_serial_open(port);
         } else {
-- 
2.27.0