LibWebView: Create plumbing for a single UI process

This allows main UI processes created while there is a currently
running one to request a new tab or a new window with the initial urls
provided on the command line. This matches (almost) the behavior of
Chromium and Firefox.

Add a new IPC protocol between two UI processes. The main UI process
will create an IPC server socket, while secondary UI processes will
connect to that socket and send over the URLs and action it wants the
main process to take.

Meta/gn/secondary/Userland/Libraries/LibWebView/BUILD.gn

@@ -84,6 +84,28 @@ compiled_action("WebDriverServerEndpoint") {
   ]
 }
 
+compiled_action("UIProcessClientEndpoint") {
+  tool = "//Meta/Lagom/Tools/CodeGenerators/IPCCompiler"
+  inputs = [ "//Userland/Libraries/LibWebView/UIProcessClient.ipc" ]
+  outputs = [ "$root_gen_dir/LibWebView/UIProcessClientEndpoint.h" ]
+  args = [
+    rebase_path(inputs[0], root_build_dir),
+    "-o",
+    rebase_path(outputs[0], root_build_dir),
+  ]
+}
+
+compiled_action("UIProcessServerEndpoint") {
+  tool = "//Meta/Lagom/Tools/CodeGenerators/IPCCompiler"
+  inputs = [ "//Userland/Libraries/LibWebView/UIProcessServer.ipc" ]
+  outputs = [ "$root_gen_dir/LibWebView/UIProcessServerEndpoint.h" ]
+  args = [
+    rebase_path(inputs[0], root_build_dir),
+    "-o",
+    rebase_path(outputs[0], root_build_dir),
+  ]
+}
+
 embed_as_string_view("generate_native_stylesheet_source") {
   input = "Native.css"
   output = "$target_gen_dir/NativeStyleSheetSource.cpp"
@@ -100,6 +122,8 @@ shared_library("LibWebView") {
     "$target_gen_dir/..",
   ]
   deps = [
+    ":UIProcessClientEndpoint",
+    ":UIProcessServerEndpoint",
     ":WebContentClientEndpoint",
     ":WebContentServerEndpoint",
     ":WebDriverClientEndpoint",
@@ -118,6 +142,7 @@ shared_library("LibWebView") {
   ]
   sources = [
     "Attribute.cpp",
+    "ChromeProcess.cpp",
     "CookieJar.cpp",
     "Database.cpp",
     "InspectorClient.cpp",
@@ -136,6 +161,8 @@ shared_library("LibWebView") {
              get_target_outputs(":WebContentServerEndpoint") +
              get_target_outputs(":WebDriverClientEndpoint") +
              get_target_outputs(":WebDriverServerEndpoint") +
+             get_target_outputs(":UIProcessClientEndpoint") +
+             get_target_outputs(":UIProcessServerEndpoint") +
              get_target_outputs(":generate_native_stylesheet_source")
   if (enable_public_suffix_list_download) {
     deps += [ ":generate_public_suffix_list_sources" ]

Userland/Libraries/LibWebView/CMakeLists.txt

@@ -2,6 +2,7 @@ include(${SerenityOS_SOURCE_DIR}/Meta/CMake/public_suffix.cmake)
 
 set(SOURCES
     Attribute.cpp
+    ChromeProcess.cpp
     CookieJar.cpp
     Database.cpp
     InspectorClient.cpp
@@ -32,6 +33,9 @@ embed_as_string_view(
     NAMESPACE "WebView"
 )
 
+compile_ipc(UIProcessServer.ipc UIProcessServerEndpoint.h)
+compile_ipc(UIProcessClient.ipc UIProcessClientEndpoint.h)
+
 set(GENERATED_SOURCES
     ${GENERATED_SOURCES}
     ../../Services/RequestServer/RequestClientEndpoint.h
@@ -41,6 +45,8 @@ set(GENERATED_SOURCES
     ../../Services/WebContent/WebDriverClientEndpoint.h
     ../../Services/WebContent/WebDriverServerEndpoint.h
     NativeStyleSheetSource.cpp
+    UIProcessClientEndpoint.h
+    UIProcessServerEndpoint.h
 )
 
 serenity_lib(LibWebView webview)

Userland/Libraries/LibWebView/ChromeProcess.cpp

@@ -0,0 +1,123 @@
+/*
+ * Copyright (c) 2024, Andrew Kaster <akaster@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#include <AK/ByteString.h>
+#include <LibCore/Process.h>
+#include <LibCore/StandardPaths.h>
+#include <LibIPC/ConnectionToServer.h>
+#include <LibWebView/ChromeProcess.h>
+
+namespace WebView {
+
+static HashMap<int, RefPtr<UIProcessConnectionFromClient>> s_connections;
+
+class UIProcessClient final
+    : public IPC::ConnectionToServer<UIProcessClientEndpoint, UIProcessServerEndpoint> {
+    C_OBJECT(UIProcessClient);
+
+private:
+    UIProcessClient(NonnullOwnPtr<Core::LocalSocket>);
+};
+
+ErrorOr<ChromeProcess::ProcessDisposition> ChromeProcess::connect(Vector<ByteString> const& raw_urls, bool new_window)
+{
+    static constexpr auto process_name = "Ladybird"sv;
+
+    auto [socket_path, pid_path] = TRY(Core::IPCProcess::paths_for_process(process_name));
+
+    if (auto pid = TRY(Core::IPCProcess::get_process_pid(process_name, pid_path)); pid.has_value()) {
+        TRY(connect_as_client(socket_path, raw_urls, new_window));
+        return ProcessDisposition::ExitProcess;
+    }
+
+    TRY(connect_as_server(socket_path));
+
+    m_pid_path = pid_path;
+    m_pid_file = TRY(Core::File::open(pid_path, Core::File::OpenMode::Write));
+    TRY(m_pid_file->write_until_depleted(ByteString::number(::getpid())));
+
+    return ProcessDisposition::ContinueMainProcess;
+}
+
+ErrorOr<void> ChromeProcess::connect_as_client(ByteString const& socket_path, Vector<ByteString> const& raw_urls, bool new_window)
+{
+    auto socket = TRY(Core::LocalSocket::connect(socket_path));
+    auto client = UIProcessClient::construct(move(socket));
+
+    if (new_window) {
+        if (!client->send_sync_but_allow_failure<Messages::UIProcessServer::CreateNewWindow>(raw_urls))
+            dbgln("Failed to send CreateNewWindow message to UIProcess");
+    } else {
+        if (!client->send_sync_but_allow_failure<Messages::UIProcessServer::CreateNewTab>(raw_urls))
+            dbgln("Failed to send CreateNewTab message to UIProcess");
+    }
+
+    return {};
+}
+
+ErrorOr<void> ChromeProcess::connect_as_server(ByteString const& socket_path)
+{
+    auto socket_fd = TRY(Core::IPCProcess::create_ipc_socket(socket_path));
+    m_socket_path = socket_path;
+    auto local_server = TRY(Core::LocalServer::try_create());
+    TRY(local_server->take_over_fd(socket_fd));
+    m_server_connection = TRY(IPC::MultiServer<UIProcessConnectionFromClient>::try_create(move(local_server)));
+
+    m_server_connection->on_new_client = [this](auto& client) {
+        client.on_new_tab = [this](auto raw_urls) {
+            if (this->on_new_tab)
+                this->on_new_tab(raw_urls);
+        };
+
+        client.on_new_window = [this](auto raw_urls) {
+            if (this->on_new_window)
+                this->on_new_window(raw_urls);
+        };
+    };
+
+    return {};
+}
+
+ChromeProcess::~ChromeProcess()
+{
+    if (m_pid_file) {
+        MUST(m_pid_file->truncate(0));
+        MUST(Core::System::unlink(m_pid_path));
+    }
+
+    if (!m_socket_path.is_empty())
+        MUST(Core::System::unlink(m_socket_path));
+}
+
+UIProcessClient::UIProcessClient(NonnullOwnPtr<Core::LocalSocket> socket)
+    : IPC::ConnectionToServer<UIProcessClientEndpoint, UIProcessServerEndpoint>(*this, move(socket))
+{
+}
+
+UIProcessConnectionFromClient::UIProcessConnectionFromClient(NonnullOwnPtr<Core::LocalSocket> socket, int client_id)
+    : IPC::ConnectionFromClient<UIProcessClientEndpoint, UIProcessServerEndpoint>(*this, move(socket), client_id)
+{
+    s_connections.set(client_id, *this);
+}
+
+void UIProcessConnectionFromClient::die()
+{
+    s_connections.remove(client_id());
+}
+
+void UIProcessConnectionFromClient::create_new_tab(Vector<ByteString> const& urls)
+{
+    if (on_new_tab)
+        on_new_tab(urls);
+}
+
+void UIProcessConnectionFromClient::create_new_window(Vector<ByteString> const& urls)
+{
+    if (on_new_window)
+        on_new_window(urls);
+}
+
+}

Userland/Libraries/LibWebView/ChromeProcess.h

@@ -0,0 +1,69 @@
+/*
+ * Copyright (c) 2024, Andrew Kaster <akaster@serenityos.org>
+ *
+ * SPDX-License-Identifier: BSD-2-Clause
+ */
+
+#pragma once
+
+#include <AK/Error.h>
+#include <AK/Function.h>
+#include <AK/OwnPtr.h>
+#include <AK/Types.h>
+#include <LibCore/Socket.h>
+#include <LibIPC/ConnectionFromClient.h>
+#include <LibIPC/Forward.h>
+#include <LibIPC/MultiServer.h>
+#include <LibWebView/UIProcessClientEndpoint.h>
+#include <LibWebView/UIProcessServerEndpoint.h>
+
+namespace WebView {
+
+class UIProcessConnectionFromClient final
+    : public IPC::ConnectionFromClient<UIProcessClientEndpoint, UIProcessServerEndpoint> {
+    C_OBJECT(UIProcessConnectionFromClient);
+
+public:
+    virtual ~UIProcessConnectionFromClient() override = default;
+
+    virtual void die() override;
+
+    Function<void(Vector<ByteString> const& urls)> on_new_tab;
+    Function<void(Vector<ByteString> const& urls)> on_new_window;
+
+private:
+    UIProcessConnectionFromClient(NonnullOwnPtr<Core::LocalSocket>, int client_id);
+
+    virtual void create_new_tab(Vector<ByteString> const& urls) override;
+    virtual void create_new_window(Vector<ByteString> const& urls) override;
+};
+
+class ChromeProcess {
+    AK_MAKE_NONCOPYABLE(ChromeProcess);
+    AK_MAKE_NONMOVABLE(ChromeProcess);
+
+public:
+    enum class ProcessDisposition : u8 {
+        ContinueMainProcess,
+        ExitProcess,
+    };
+
+    ChromeProcess() = default;
+    ~ChromeProcess();
+
+    ErrorOr<ProcessDisposition> connect(Vector<ByteString> const& raw_urls, bool new_window);
+
+    Function<void(Vector<ByteString> const& raw_urls)> on_new_tab;
+    Function<void(Vector<ByteString> const& raw_urls)> on_new_window;
+
+private:
+    ErrorOr<void> connect_as_client(ByteString const& socket_path, Vector<ByteString> const& raw_urls, bool new_window);
+    ErrorOr<void> connect_as_server(ByteString const& socket_path);
+
+    OwnPtr<IPC::MultiServer<UIProcessConnectionFromClient>> m_server_connection;
+    OwnPtr<Core::File> m_pid_file;
+    ByteString m_pid_path;
+    ByteString m_socket_path;
+};
+
+}

Userland/Libraries/LibWebView/UIProcessClient.ipc

@@ -0,0 +1,2 @@
+endpoint UIProcessClient {
+}

Userland/Libraries/LibWebView/UIProcessServer.ipc

@@ -0,0 +1,4 @@
+endpoint UIProcessServer {
+    create_new_tab(Vector<ByteString> urls) => ()
+    create_new_window(Vector<ByteString> urls) => ()
+}