[Qemu-devel] [PATCH 4/4] virtio-console: Add a in-qemu api for open/read/write/close ports

[Amit Shah <amit.shah@redhat.com>]

This is a simple-to-use api for opening a port, registering
a callback for read, writing to a port and closing it.

Signed-off-by: Amit Shah <amit.shah@redhat.com>
---
 hw/virtio-console.c |   67 ++++++++++++++++++++++++++++++++++++++++++++++++--
 hw/virtio-console.h |    5 ++++
 2 files changed, 69 insertions(+), 3 deletions(-)

diff --git a/hw/virtio-console.c b/hw/virtio-console.c
index d750c8e..c41f13c 100644
--- a/hw/virtio-console.c
+++ b/hw/virtio-console.c
@@ -58,6 +58,11 @@ struct VirtIOConsolePort {
 
     QTAILQ_HEAD(, VirtIOConsolePortBuffer) unflushed_buffer_head;
 
+    /* Callback that's invoked when we have a buffer that can be consumed
+     * by an in-qemu user of this port
+     */
+    size_t (*read_callback)(const uint8_t *buf, const size_t len);
+
     bool guest_connected;
     bool host_connected;
 };
@@ -128,10 +133,15 @@ static bool has_complete_data(VirtIOConsolePort *port)
 
 static size_t flush_buf(VirtIOConsolePort *port, const uint8_t *buf, size_t len)
 {
-    if (!port->hd) {
-        return 0;
+    int ret;
+
+    ret = 0;
+    if (port->read_callback) {
+        ret = port->read_callback(buf, len);
+    } else if (port->hd) {
+        ret = qemu_chr_write(port->hd, buf, len);
     }
-    return qemu_chr_write(port->hd, buf, len);
+    return ret;
 }
 
 static void flush_queue(VirtIOConsolePort *port)
@@ -443,6 +453,57 @@ static void vcon_event(void *opaque, int event)
     send_control_event(port, &cpkt);
 }
 
+
+/* Functions for use inside qemu to open and read from/write to ports */
+VirtIOConsolePort *virtio_console_open(uint32_t id,
+                                       size_t(*read_callback)(const uint8_t*buf,
+                                                              const size_t len))
+{
+    VirtIOConsolePort *port;
+    struct virtio_console_control cpkt;
+
+    port = get_port_from_id(virtio_console, id);
+    if (!port) {
+        return NULL;
+    }
+    /* Don't allow opening an already-open port */
+    if (port->host_connected) {
+        return NULL;
+    }
+    port->read_callback = read_callback;
+
+    /* Send port open notification to the guest */
+    port->host_connected = true;
+    cpkt.event = VIRTIO_CONSOLE_PORT_OPEN;
+    cpkt.value = 1;
+    send_control_event(port, &cpkt);
+
+    return port;
+}
+
+void virtio_console_close(VirtIOConsolePort *port)
+{
+    struct virtio_console_control cpkt;
+
+    if (!port)
+        return;
+
+    port->read_callback = NULL;
+
+    cpkt.event = VIRTIO_CONSOLE_PORT_OPEN;
+    cpkt.value = 0;
+    send_control_event(port, &cpkt);
+}
+
+size_t virtio_console_write(VirtIOConsolePort *port, uint8_t *buf, size_t size)
+{
+    if (!port || !port->host_connected) {
+        return 0;
+    }
+    return write_to_port(port, buf, size, false);
+}
+
+
 static void set_active_in_map(uint32_t *map, uint32_t idx)
 {
     int i;
diff --git a/hw/virtio-console.h b/hw/virtio-console.h
index 526713e..5f0f549 100644
--- a/hw/virtio-console.h
+++ b/hw/virtio-console.h
@@ -88,5 +88,10 @@ VirtConBus *virtcon_bus_new(DeviceState *dev);
 typedef struct VirtIOConsolePort VirtIOConsolePort;
 void virtio_console_monitor_command(Monitor *mon,
                                     const char *command, const char *param);
+VirtIOConsolePort *virtio_console_open(uint32_t id,
+                                       size_t(*read_callback)(const uint8_t*buf,
+                                                              const size_t len));
+void virtio_console_close(VirtIOConsolePort *port);
+size_t virtio_console_write(VirtIOConsolePort *port, uint8_t *buf, size_t size);
 
 #endif
-- 
1.6.2.5