Introduce user.updateUser

Unify updatePassword and updateRealname into a single function. This
allows "user update" to be atomic.

service.go

@@ -775,19 +775,22 @@ func handleUserUpdate(dc *downstreamConn, params []string) error {
 		return err
 	}
 
+	// copy the user record because we'll mutate it
+	record := dc.user.User
+
 	if password != nil {
 		hashed, err := bcrypt.GenerateFromPassword([]byte(*password), bcrypt.DefaultCost)
 		if err != nil {
 			return fmt.Errorf("failed to hash password: %v", err)
 		}
-		if err := dc.user.updatePassword(string(hashed)); err != nil {
-			return err
-		}
+		record.Password = string(hashed)
 	}
 	if realname != nil {
-		if err := dc.user.updateRealname(*realname); err != nil {
-			return err
-		}
+		record.Realname = *realname
+	}
+
+	if err := dc.user.updateUser(&record); err != nil {
+		return err
 	}
 
 	sendServicePRIVMSG(dc, fmt.Sprintf("updated user %q", dc.user.Username))

user.go

@@ -856,33 +856,38 @@ func (u *user) deleteNetwork(id int64) error {
 	return nil
 }
 
-func (u *user) updatePassword(hashed string) error {
-	u.User.Password = hashed
-	return u.srv.db.StoreUser(&u.User)
-}
+func (u *user) updateUser(record *User) error {
+	if u.ID != record.ID {
+		panic("ID mismatch when updating user")
+	}
 
-func (u *user) updateRealname(realname string) error {
-	u.User.Realname = realname
-	if err := u.srv.db.StoreUser(&u.User); err != nil {
+	realnameUpdated := u.Realname != record.Realname
+	if err := u.srv.db.StoreUser(record); err != nil {
 		return fmt.Errorf("failed to update user %q: %v", u.Username, err)
 	}
+	u.User = *record
 
-	// Re-connect to networks which use the default realname
-	var needUpdate []Network
-	u.forEachNetwork(func(net *network) {
-		if net.Realname == "" {
-			needUpdate = append(needUpdate, net.Network)
+	if realnameUpdated {
+		// Re-connect to networks which use the default realname
+		var needUpdate []Network
+		u.forEachNetwork(func(net *network) {
+			if net.Realname == "" {
+				needUpdate = append(needUpdate, net.Network)
+			}
+		})
+
+		var netErr error
+		for _, net := range needUpdate {
+			if _, err := u.updateNetwork(&net); err != nil {
+				netErr = err
+			}
 		}
-	})
-
-	var netErr error
-	for _, net := range needUpdate {
-		if _, err := u.updateNetwork(&net); err != nil {
-			netErr = err
+		if netErr != nil {
+			return netErr
 		}
 	}
 
-	return netErr
+	return nil
 }
 
 func (u *user) stop() {