feat: allow custom v8 snapshots to be used in the main process and th…

…e default snapshot in the renderer process (#35694) feat: allow custom v8 snapshots to be used in the main process and the default snapshot in the renderer process (#35266) * Updates to allow for using a custom v8 snapshot file name * Allow using a custom v8 snapshot file name * Fix up patch due to merge * Use fuse to set up custom v8 snapshot file in browser process * Refactor to use delegate instead of command line parameter * Refactoring * Update due to merge * PR comments * Rename patch * Rename patch chore: update patches Co-authored-by: Ryan Manuel <ryanm@cypress.io>
electron · Sep 22, 2022 · 9e419bc · 9e419bc
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diff --git a/build/fuses/fuses.json5 b/build/fuses/fuses.json5
@@ -7,5 +7,6 @@
   "node_options": "1",
   "node_cli_inspect": "1",
   "embedded_asar_integrity_validation": "0",
-  "only_load_app_from_asar": "0"
+  "only_load_app_from_asar": "0",
+  "load_browser_process_specific_v8_snapshot": "0"
 }
diff --git a/docs/tutorial/fuses.md b/docs/tutorial/fuses.md
@@ -54,6 +54,13 @@ For more information on how to use asar integrity validation please read the [As
 
 The onlyLoadAppFromAsar fuse changes the search system that Electron uses to locate your app code.  By default Electron will search in the following order `app.asar` -> `app` -> `default_app.asar`.  When this fuse is enabled the search order becomes a single entry `app.asar` thus ensuring that when combined with the `embeddedAsarIntegrityValidation` fuse it is impossible to load non-validated code.
 
+### `loadBrowserProcessSpecificV8Snapshot`
+
+**Default:** Disabled
+**@electron/fuses:** `FuseV1Options.LoadBrowserProcessSpecificV8Snapshot`
+
+The loadBrowserProcessSpecificV8Snapshot fuse changes which V8 snapshot file is used for the browser process.  By default Electron's processes will all use the same V8 snapshot file.  When this fuse is enabled the browser process uses the file called `browser_v8_context_snapshot.bin` for its V8 snapshot. The other processes will use the V8 snapshot file that they normally do.
+
 ## How do I flip the fuses?
 
 ### The easy way

diff --git a/patches/chromium/.patches b/patches/chromium/.patches
@@ -124,3 +124,4 @@ feat_add_set_can_resize_mutator.patch
 cherry-pick-2083e894852c.patch
 cherry-pick-51daffbf5cd8.patch
 dpwa_enable_window_controls_overlay_by_default.patch
+create_browser_v8_snapshot_file_name_fuse.patch
diff --git a/patches/chromium/create_browser_v8_snapshot_file_name_fuse.patch b/patches/chromium/create_browser_v8_snapshot_file_name_fuse.patch
@@ -0,0 +1,156 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Ryan Manuel <ryanm@cypress.io>
+Date: Thu, 4 Aug 2022 22:37:01 -0500
+Subject: Create browser v8 snapshot file name fuse
+
+By default, chromium sets up one v8 snapshot to be used in all v8 contexts. This patch allows consumers
+to have a dedicated browser process v8 snapshot defined by the file `browser_v8_context_snapshot.bin`.
+
+diff --git a/content/app/content_main_runner_impl.cc b/content/app/content_main_runner_impl.cc
+index 328f8b800c36544f7906536416ac61dc87cc45d3..2f973efcf3e38edcc74060929339fc21bdf0aa3b 100644
+--- a/content/app/content_main_runner_impl.cc
++++ b/content/app/content_main_runner_impl.cc
+@@ -37,6 +37,7 @@
+ #include "base/process/memory.h"
+ #include "base/process/process.h"
+ #include "base/process/process_handle.h"
++#include "base/strings/string_piece.h"
+ #include "base/strings/string_number_conversions.h"
+ #include "base/strings/string_util.h"
+ #include "base/task/thread_pool/thread_pool_instance.h"
+@@ -232,8 +233,13 @@ std::string GetSnapshotDataDescriptor(const base::CommandLine& command_line) {
+
+ #endif
+
+-void LoadV8SnapshotFile(const base::CommandLine& command_line) {
++void LoadV8SnapshotFile(const raw_ptr<ContentMainDelegate> delegate, const base::CommandLine& command_line) {
+   const gin::V8SnapshotFileType snapshot_type = GetSnapshotType(command_line);
++  base::StringPiece browser_v8_snapshot_file_name = delegate->GetBrowserV8SnapshotFilename();
++  if (!browser_v8_snapshot_file_name.empty()) {
++    gin::V8Initializer::LoadV8SnapshotFromFileName(browser_v8_snapshot_file_name, snapshot_type);
++    return;
++  }
+ #if BUILDFLAG(IS_POSIX) && !BUILDFLAG(IS_MAC)
+   base::FileDescriptorStore& file_descriptor_store =
+       base::FileDescriptorStore::GetInstance();
+@@ -262,11 +268,12 @@ bool ShouldLoadV8Snapshot(const base::CommandLine& command_line,
+
+ #endif  // V8_USE_EXTERNAL_STARTUP_DATA
+
+-void LoadV8SnapshotIfNeeded(const base::CommandLine& command_line,
++void LoadV8SnapshotIfNeeded(const raw_ptr<ContentMainDelegate> delegate,
++                            const base::CommandLine& command_line,
+                             const std::string& process_type) {
+ #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
+   if (ShouldLoadV8Snapshot(command_line, process_type))
+-    LoadV8SnapshotFile(command_line);
++    LoadV8SnapshotFile(delegate, command_line);
+ #endif  // V8_USE_EXTERNAL_STARTUP_DATA
+ }
+
+@@ -917,7 +924,7 @@ int ContentMainRunnerImpl::Initialize(ContentMainParams params) {
+     return TerminateForFatalInitializationError();
+ #endif  // BUILDFLAG(IS_ANDROID) && (ICU_UTIL_DATA_IMPL == ICU_UTIL_DATA_FILE)
+
+-  LoadV8SnapshotIfNeeded(command_line, process_type);
++  LoadV8SnapshotIfNeeded(delegate_, command_line, process_type);
+
+   blink::TrialTokenValidator::SetOriginTrialPolicyGetter(
+       base::BindRepeating([]() -> blink::OriginTrialPolicy* {
+diff --git a/content/public/app/content_main_delegate.cc b/content/public/app/content_main_delegate.cc
+index ce6b8b454d0cc57ec4de81c7a19b5e0f0087a162..c421d3b5bc02b702e89c714d3d521207cbca156b 100644
+--- a/content/public/app/content_main_delegate.cc
++++ b/content/public/app/content_main_delegate.cc
+@@ -5,6 +5,7 @@
+ #include "content/public/app/content_main_delegate.h"
+
+ #include "base/check.h"
++#include "base/strings/string_piece.h"
+ #include "build/build_config.h"
+ #include "content/public/browser/content_browser_client.h"
+ #include "content/public/common/content_client.h"
+@@ -55,6 +56,10 @@ ContentMainDelegate::CreateVariationsIdsProvider() {
+   return nullptr;
+ }
+
++base::StringPiece ContentMainDelegate::GetBrowserV8SnapshotFilename() {
++  return base::StringPiece();
++}
++
+ ContentClient* ContentMainDelegate::CreateContentClient() {
+   return new ContentClient();
+ }
+diff --git a/content/public/app/content_main_delegate.h b/content/public/app/content_main_delegate.h
+index f81430b564a3cf44c2168e18c4c53c6629353d75..34a5531cd33b439114a796adc71af7251b6b1f81 100644
+--- a/content/public/app/content_main_delegate.h
++++ b/content/public/app/content_main_delegate.h
+@@ -9,6 +9,7 @@
+ #include <string>
+ #include <vector>
+
++#include "base/strings/string_piece.h"
+ #include "build/build_config.h"
+ #include "content/common/content_export.h"
+ #include "content/public/common/main_function_params.h"
+@@ -149,6 +150,8 @@ class CONTENT_EXPORT ContentMainDelegate {
+   virtual bool ShouldHandleConsoleControlEvents();
+ #endif
+
++  virtual base::StringPiece GetBrowserV8SnapshotFilename();
++
+  protected:
+   friend class ContentClientCreator;
+   friend class ContentClientInitializer;
+diff --git a/gin/v8_initializer.cc b/gin/v8_initializer.cc
+index 34a65998cbaa22241fd7c6cc60d8ab01982ca3ce..68c12e9bb1f334d6fec050018da8bc0a6db4a850 100644
+--- a/gin/v8_initializer.cc
++++ b/gin/v8_initializer.cc
+@@ -512,8 +512,7 @@ void V8Initializer::GetV8ExternalSnapshotData(const char** snapshot_data_out,
+
+ #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
+
+-// static
+-void V8Initializer::LoadV8Snapshot(V8SnapshotFileType snapshot_file_type) {
++void V8Initializer::LoadV8SnapshotFromFileName(base::StringPiece file_name, V8SnapshotFileType snapshot_file_type) {
+   if (g_mapped_snapshot) {
+     // TODO(crbug.com/802962): Confirm not loading different type of snapshot
+     // files in a process.
+@@ -522,10 +521,17 @@ void V8Initializer::LoadV8Snapshot(V8SnapshotFileType snapshot_file_type) {
+
+   base::MemoryMappedFile::Region file_region;
+   base::File file =
+-      OpenV8File(GetSnapshotFileName(snapshot_file_type), &file_region);
++      OpenV8File(file_name.data(), &file_region);
+   LoadV8SnapshotFromFile(std::move(file), &file_region, snapshot_file_type);
+ }
+
++// static
++void V8Initializer::LoadV8Snapshot(V8SnapshotFileType snapshot_file_type) {
++  const char* file_name = GetSnapshotFileName(snapshot_file_type);
++
++  LoadV8SnapshotFromFileName(file_name, snapshot_file_type);
++}
++
+ // static
+ void V8Initializer::LoadV8SnapshotFromFile(
+     base::File snapshot_file,
+diff --git a/gin/v8_initializer.h b/gin/v8_initializer.h
+index 13a120c7fe8e69a44793473f3124c33d572a07a3..acb294780873c1d84546eb2b9acc00f86838361d 100644
+--- a/gin/v8_initializer.h
++++ b/gin/v8_initializer.h
+@@ -9,6 +9,7 @@
+
+ #include "base/files/file.h"
+ #include "base/files/memory_mapped_file.h"
++#include "base/strings/string_piece.h"
+ #include "build/build_config.h"
+ #include "gin/array_buffer.h"
+ #include "gin/gin_export.h"
+@@ -42,6 +43,7 @@ class GIN_EXPORT V8Initializer {
+                                         int* snapshot_size_out);
+
+ #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
++  static void LoadV8SnapshotFromFileName(base::StringPiece file_name, V8SnapshotFileType snapshot_file_type);
+   // Load V8 snapshot from default resources, if they are available.
+   static void LoadV8Snapshot(
+       V8SnapshotFileType snapshot_file_type = V8SnapshotFileType::kDefault);
diff --git a/shell/app/electron_main_delegate.cc b/shell/app/electron_main_delegate.cc
@@ -23,6 +23,7 @@
 #include "components/content_settings/core/common/content_settings_pattern.h"
 #include "content/public/common/content_switches.h"
 #include "electron/buildflags/buildflags.h"
+#include "electron/fuses.h"
 #include "extensions/common/constants.h"
 #include "ipc/ipc_buildflags.h"
 #include "sandbox/policy/switches.h"
@@ -420,6 +421,20 @@ void ElectronMainDelegate::PreBrowserMain() {
 #endif
 }
 
+base::StringPiece ElectronMainDelegate::GetBrowserV8SnapshotFilename() {
+  const base::CommandLine* command_line =
+      base::CommandLine::ForCurrentProcess();
+  std::string process_type =
+      command_line->GetSwitchValueASCII(::switches::kProcessType);
+  bool load_browser_process_specific_v8_snapshot =
+      process_type.empty() &&
+      electron::fuses::IsLoadBrowserProcessSpecificV8SnapshotEnabled();
+  if (load_browser_process_specific_v8_snapshot) {
+    return "browser_v8_context_snapshot.bin";
+  }
+  return ContentMainDelegate::GetBrowserV8SnapshotFilename();
+}
+
 content::ContentBrowserClient*
 ElectronMainDelegate::CreateContentBrowserClient() {
   browser_client_ = std::make_unique<ElectronBrowserClient>();

diff --git a/shell/app/electron_main_delegate.h b/shell/app/electron_main_delegate.h
@@ -30,6 +30,8 @@ class ElectronMainDelegate : public content::ContentMainDelegate {
   ElectronMainDelegate(const ElectronMainDelegate&) = delete;
   ElectronMainDelegate& operator=(const ElectronMainDelegate&) = delete;
 
+  base::StringPiece GetBrowserV8SnapshotFilename() override;
+
  protected:
   // content::ContentMainDelegate:
   bool BasicStartupComplete(int* exit_code) override;