fix(linux): don't share UserContentManager between webviews (v0.24) (#…

…1325)

Fixes #1308

Init scripts are registered to the `UserContentManager`, so if it is shared between `WebView`s, the init scripts conflict. Use a unique `UserContentManager` for each `WebView` instead of sharing it across the `WebContext`.

The IPC message handler is also registered to `UserContentManager`.

Also changed from `register_uri_scheme` to `try_register_uri_scheme`, which doesn't attempt to register a URI scheme if we already know that one with the same name was registered to the `WebContext` before. Without this change, I get this error from WebKitGTK:
```
** (tauri-app:[...]): CRITICAL **: 14:03:50.040: Cannot register URI scheme tauri more than once
```
It doesn't seem to affect functionality, but better to issue a more appropriate warning on our side. (On dev, this is propagated as an error)

.changes/linux-shared-webcontext-ipc.md

@@ -0,0 +1,5 @@
+---
+"wry": patch
+---
+
+Fix Linux IPC handler and initialization scripts when sharing a WebContext between multiple WebViews.

src/webview/webkitgtk/mod.rs

@@ -17,7 +17,8 @@ use std::{
 use url::Url;
 use webkit2gtk::{
   traits::*, LoadEvent, NavigationPolicyDecision, PolicyDecisionType, URIRequest,
-  UserContentInjectedFrames, UserScript, UserScriptInjectionTime, WebView, WebViewBuilder,
+  UserContentInjectedFrames, UserContentManager, UserScript, UserScriptInjectionTime, WebView,
+  WebViewBuilder,
 };
 use webkit2gtk_sys::{
   webkit_get_major_version, webkit_get_micro_version, webkit_get_minor_version,
@@ -63,9 +64,11 @@ impl InnerWebView {
       }
     };
 
+    let manager = UserContentManager::new();
+
     let webview = {
       let mut webview = WebViewBuilder::new();
-      webview = webview.user_content_manager(web_context.manager());
+      webview = webview.user_content_manager(&manager);
       webview = webview.web_context(web_context.context());
       webview = webview.is_controlled_by_automation(web_context.allows_automation());
       webview.build()
@@ -77,8 +80,6 @@ impl InnerWebView {
     let webview = Rc::new(webview);
     let w = window_rc.clone();
     let ipc_handler = attributes.ipc_handler.take();
-    let manager = web_context.manager();
-
     // Use the window hash as the script handler name to prevent from conflict when sharing same
     // web context.
     let window_hash = {
@@ -99,8 +100,8 @@ impl InnerWebView {
       }
     });
 
-    // Register the handler we just connected
-    manager.register_script_message_handler(&window_hash);
+    // Register handler on JS side
+    manager.register_script_message_handler("ipc");
 
     // Allow the webview to close it's own window
     let close_window = window_rc.clone();
@@ -355,10 +356,11 @@ impl InnerWebView {
     }
 
     for (name, handler) in attributes.custom_protocols {
-      match web_context.register_uri_scheme(&name, handler) {
+      match web_context.try_register_uri_scheme(&name, handler) {
         // Swallow duplicate scheme errors to preserve current behavior.
-        // FIXME: we should log this error in the future
-        Err(Error::DuplicateCustomProtocol(_)) => (),
+        Err(Error::DuplicateCustomProtocol(_)) => {
+          log::warn!("Ignoring already registered custom protocol {name}");
+        }
         Err(e) => return Err(e),
         Ok(_) => (),
       }

src/webview/webkitgtk/web_context.rs

@@ -21,14 +21,13 @@ use std::{
 };
 use url::Url;
 use webkit2gtk::{
-  traits::*, ApplicationInfo, CookiePersistentStorage, LoadEvent, URIRequest, UserContentManager,
-  WebContext, WebContextBuilder, WebView, WebsiteDataManagerBuilder,
+  traits::*, ApplicationInfo, CookiePersistentStorage, LoadEvent, URIRequest, WebContext,
+  WebContextBuilder, WebView, WebsiteDataManagerBuilder,
 };
 
 #[derive(Debug)]
 pub struct WebContextImpl {
   context: WebContext,
-  manager: UserContentManager,
   webview_uri_loader: Rc<WebviewUriLoader>,
   registered_protocols: HashSet<String>,
   automation: bool,
@@ -82,7 +81,6 @@ impl WebContextImpl {
     Self {
       context,
       automation,
-      manager: UserContentManager::new(),
       registered_protocols: Default::default(),
       webview_uri_loader: Rc::default(),
       app_info: Some(app_info),
@@ -101,9 +99,6 @@ pub trait WebContextExt {
   /// The GTK [`WebContext`] of all webviews in the context.
   fn context(&self) -> &WebContext;
 
-  /// The GTK [`UserContentManager`] of all webviews in the context.
-  fn manager(&self) -> &UserContentManager;
-
   /// Register a custom protocol to the web context.
   ///
   /// When duplicate schemes are registered, the duplicate handler will still be submitted and the
@@ -150,10 +145,6 @@ impl WebContextExt for super::WebContext {
     &self.os.context
   }
 
-  fn manager(&self) -> &UserContentManager {
-    &self.os.manager
-  }
-
   fn register_uri_scheme<F>(&mut self, name: &str, handler: F) -> crate::Result<()>
   where
     F: Fn(&Request<Vec<u8>>) -> crate::Result<Response<Cow<'static, [u8]>>> + 'static,