Add qvm doctor command to diagnose and fix common issues

internal/qmp/client.go

@@ -73,3 +73,88 @@ func (c *Client) Shutdown() mo.Result[struct{}] {
 func (c *Client) Close() error {
 	return c.monitor.Disconnect()
 }
+
+// AddChardev adds a vhost-user-fs chardev for a virtiofsd socket.
+// This is the first step of hot-mounting a filesystem.
+func (c *Client) AddChardev(id, socketPath string) mo.Result[struct{}] {
+	cmd := fmt.Sprintf(`{"execute":"chardev-add","arguments":{"id":"%s","backend":{"type":"socket","data":{"addr":{"type":"unix","data":{"path":"%s"}},"server":false}}}}`, id, socketPath)
+	raw, err := c.monitor.Run([]byte(cmd))
+	if err != nil {
+		return mo.Err[struct{}](fmt.Errorf("failed to add chardev %s: %w", id, err))
+	}
+
+	// Check for error in response
+	var resp map[string]interface{}
+	if err := json.Unmarshal(raw, &resp); err == nil {
+		if errObj, ok := resp["error"]; ok {
+			return mo.Err[struct{}](fmt.Errorf("QMP error adding chardev: %v", errObj))
+		}
+	}
+
+	return mo.Ok(struct{}{})
+}
+
+// AddVhostUserFsDevice adds a vhost-user-fs-pci device connected to a chardev.
+// This is the second step of hot-mounting a filesystem.
+func (c *Client) AddVhostUserFsDevice(chardevID, tag string) mo.Result[struct{}] {
+	// Device ID must be unique, derive from chardev ID
+	deviceID := "dev_" + chardevID
+	cmd := fmt.Sprintf(`{"execute":"device_add","arguments":{"driver":"vhost-user-fs-pci","chardev":"%s","tag":"%s","id":"%s","queue-size":1024}}`, chardevID, tag, deviceID)
+	raw, err := c.monitor.Run([]byte(cmd))
+	if err != nil {
+		return mo.Err[struct{}](fmt.Errorf("failed to add vhost-user-fs device for %s: %w", tag, err))
+	}
+
+	// Check for error in response
+	var resp map[string]interface{}
+	if err := json.Unmarshal(raw, &resp); err == nil {
+		if errObj, ok := resp["error"]; ok {
+			return mo.Err[struct{}](fmt.Errorf("QMP error adding device: %v", errObj))
+		}
+	}
+
+	return mo.Ok(struct{}{})
+}
+
+// HotMountFilesystem performs a complete hot-mount of a virtiofsd filesystem.
+// Requires the virtiofsd daemon to already be running and listening on socketPath.
+func (c *Client) HotMountFilesystem(tag, socketPath string) mo.Result[struct{}] {
+	// Use tag as chardev ID for simplicity
+	chardevID := tag
+
+	// Step 1: Add chardev
+	if result := c.AddChardev(chardevID, socketPath); result.IsError() {
+		return result
+	}
+
+	// Step 2: Add device
+	if result := c.AddVhostUserFsDevice(chardevID, tag); result.IsError() {
+		return result
+	}
+
+	return mo.Ok(struct{}{})
+}
+
+// QueryChardevs lists all current chardevs to check if one exists.
+func (c *Client) QueryChardevs() mo.Result[[]string] {
+	cmd := []byte(`{"execute":"query-chardev"}`)
+	raw, err := c.monitor.Run(cmd)
+	if err != nil {
+		return mo.Err[[]string](fmt.Errorf("failed to query chardevs: %w", err))
+	}
+
+	var resp struct {
+		Return []struct {
+			Label string `json:"label"`
+		} `json:"return"`
+	}
+	if err := json.Unmarshal(raw, &resp); err != nil {
+		return mo.Err[[]string](fmt.Errorf("failed to parse chardev response: %w", err))
+	}
+
+	var labels []string
+	for _, c := range resp.Return {
+		labels = append(labels, c.Label)
+	}
+	return mo.Ok(labels)
+}