Add support to extension_shell and ash_shell to use external V8 snapshot files.

gin/v8_initializer.cc

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "gin/v8_initializer.h"
 
 #include "base/basictypes.h"
 #include "base/files/file.h"
 #include "base/files/file_path.h"
 #include "base/files/memory_mapped_file.h"
 #include "base/logging.h"
 #include "base/rand_util.h"
 #include "base/strings/sys_string_conversions.h"
 #include "crypto/sha2.h"
 
 #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
 #if defined(OS_MACOSX)
 #include "base/mac/foundation_util.h"
 #endif  // OS_MACOSX
 #include "base/path_service.h"
 #endif  // V8_USE_EXTERNAL_STARTUP_DATA
 
 namespace gin {
 
 namespace {
 
-bool GenerateEntropy(unsigned char* buffer, size_t amount) {
-  base::RandBytes(buffer, amount);
-  return true;
-}
-
 base::MemoryMappedFile* g_mapped_natives = nullptr;
 base::MemoryMappedFile* g_mapped_snapshot = nullptr;
 
 #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
+#if !defined(OS_MACOSX)
+const int kV8SnapshotBasePathKey =
+#if defined(OS_ANDROID)
+    base::DIR_ANDROID_APP_DATA;
+#elif defined(OS_POSIX)
+    base::DIR_EXE;
+#elif defined(OS_WIN)
+    base::DIR_MODULE;
+#endif  // OS_ANDROID
+#endif  // !OS_MACOSX
+
+const char kNativesFileName[] = "natives_blob.bin";
+const char kSnapshotFileName[] = "snapshot_blob.bin";
+
+void GetV8FilePaths(base::FilePath* natives_path_out,
+                    base::FilePath* snapshot_path_out) {
+#if !defined(OS_MACOSX)
+  base::FilePath data_path;
+  PathService::Get(kV8SnapshotBasePathKey, &data_path);
+  DCHECK(!data_path.empty());
+
+  *natives_path_out = data_path.AppendASCII(kNativesFileName);
+  *snapshot_path_out = data_path.AppendASCII(kSnapshotFileName);
+#else   // !defined(OS_MACOSX)
+  base::ScopedCFTypeRef<CFStringRef> natives_file_name(
+      base::SysUTF8ToCFStringRef(kNativesFileName));
+  *natives_path_out =
+      base::mac::PathForFrameworkBundleResource(natives_file_name);
+  base::ScopedCFTypeRef<CFStringRef> snapshot_file_name(
+      base::SysUTF8ToCFStringRef(kSnapshotFileName));
+  *snapshot_path_out =
+      base::mac::PathForFrameworkBundleResource(snapshot_file_name);
+  DCHECK(!natives_path_out->empty());
+  DCHECK(!snapshot_path_out->empty());
+#endif  // !defined(OS_MACOSX)
+}
+
 bool MapV8Files(base::File natives_file,
                 base::File snapshot_file,
                 base::MemoryMappedFile::Region natives_region =
                     base::MemoryMappedFile::Region::kWholeFile,
                 base::MemoryMappedFile::Region snapshot_region =
                     base::MemoryMappedFile::Region::kWholeFile) {
   g_mapped_natives = new base::MemoryMappedFile;
   if (!g_mapped_natives->IsValid()) {
     if (!g_mapped_natives->Initialize(natives_file.Pass(), natives_region)) {
       delete g_mapped_natives;
@@ skipping 22 matching lines @@
   unsigned char output[crypto::kSHA256Length];
   crypto::SHA256HashString(
       base::StringPiece(reinterpret_cast<const char*>(snapshot_file->data()),
                         snapshot_file->length()),
       output, sizeof(output));
   return !memcmp(fingerprint, output, sizeof(output));
 }
 #endif  // V8_VERIFY_EXTERNAL_STARTUP_DATA
 #endif  // V8_USE_EXTERNAL_STARTUP_DATA
 
+bool GenerateEntropy(unsigned char* buffer, size_t amount) {
+  base::RandBytes(buffer, amount);
+  return true;
+}
+
 }  // namespace
 
 #if defined(V8_USE_EXTERNAL_STARTUP_DATA)
-
 #if defined(V8_VERIFY_EXTERNAL_STARTUP_DATA)
 // Defined in gen/gin/v8_snapshot_fingerprint.cc
 extern const unsigned char g_natives_fingerprint[];
 extern const unsigned char g_snapshot_fingerprint[];
 #endif  // V8_VERIFY_EXTERNAL_STARTUP_DATA
 
-#if !defined(OS_MACOSX)
-const int V8Initializer::kV8SnapshotBasePathKey =
-#if defined(OS_ANDROID)
-    base::DIR_ANDROID_APP_DATA;
-#elif defined(OS_POSIX)
-    base::DIR_EXE;
-#elif defined(OS_WIN)
-    base::DIR_MODULE;
-#endif  // OS_ANDROID
-#endif  // !OS_MACOSX
-
-const char V8Initializer::kNativesFileName[] = "natives_blob.bin";
-const char V8Initializer::kSnapshotFileName[] = "snapshot_blob.bin";
-
 // static
 bool V8Initializer::LoadV8Snapshot() {
   if (g_mapped_natives && g_mapped_snapshot)
     return true;
 
-#if !defined(OS_MACOSX)
-  base::FilePath data_path;
-  PathService::Get(kV8SnapshotBasePathKey, &data_path);
-  DCHECK(!data_path.empty());
-
-  base::FilePath natives_path = data_path.AppendASCII(kNativesFileName);
-  base::FilePath snapshot_path = data_path.AppendASCII(kSnapshotFileName);
-#else   // !defined(OS_MACOSX)
-  base::ScopedCFTypeRef<CFStringRef> natives_file_name(
-      base::SysUTF8ToCFStringRef(kNativesFileName));
-  base::FilePath natives_path =
-      base::mac::PathForFrameworkBundleResource(natives_file_name);
-  base::ScopedCFTypeRef<CFStringRef> snapshot_file_name(
-      base::SysUTF8ToCFStringRef(kSnapshotFileName));
-  base::FilePath snapshot_path =
-      base::mac::PathForFrameworkBundleResource(snapshot_file_name);
-  DCHECK(!natives_path.empty());
-  DCHECK(!snapshot_path.empty());
-#endif  // !defined(OS_MACOSX)
+  base::FilePath natives_data_path;
+  base::FilePath snapshot_data_path;
+  GetV8FilePaths(&natives_data_path, &snapshot_data_path);
 
   int flags = base::File::FLAG_OPEN | base::File::FLAG_READ;
-  if (!MapV8Files(base::File(natives_path, flags),
-                  base::File(snapshot_path, flags)))
+  if (!MapV8Files(base::File(natives_data_path, flags),
+                  base::File(snapshot_data_path, flags)))
     return false;
 
 #if defined(V8_VERIFY_EXTERNAL_STARTUP_DATA)
   return VerifyV8SnapshotFile(g_mapped_natives, g_natives_fingerprint) &&
          VerifyV8SnapshotFile(g_mapped_snapshot, g_snapshot_fingerprint);
 #else
   return true;
 #endif  // V8_VERIFY_EXTERNAL_STARTUP_DATA
 }
 
@@ skipping 18 matching lines @@
       base::MemoryMappedFile::Region::kWholeFile;
   if (natives_size != 0 || natives_offset != 0) {
     snapshot_region =
         base::MemoryMappedFile::Region(snapshot_offset, snapshot_size);
   }
 
   return MapV8Files(base::File(natives_pf), base::File(snapshot_pf),
                     natives_region, snapshot_region);
 }
 
+// static
+bool V8Initializer::OpenV8FilesForChildProcesses(
+    base::PlatformFile* natives_fd_out,
+    base::PlatformFile* snapshot_fd_out) {
+  base::FilePath natives_data_path;
+  base::FilePath snapshot_data_path;
+  GetV8FilePaths(&natives_data_path, &snapshot_data_path);
+
+  int file_flags = base::File::FLAG_OPEN | base::File::FLAG_READ;
+  base::File natives_data_file(natives_data_path, file_flags);
+  base::File snapshot_data_file(snapshot_data_path, file_flags);
+
+  if (!natives_data_file.IsValid() || !snapshot_data_file.IsValid())
+    return false;
+
+  *natives_fd_out = natives_data_file.TakePlatformFile();
+  *snapshot_fd_out = snapshot_data_file.TakePlatformFile();
+  return true;
+}
+
 #endif  // V8_USE_EXTERNAL_STARTUP_DATA
 
 // static
 void V8Initializer::Initialize(gin::IsolateHolder::ScriptMode mode,
                                v8::ArrayBuffer::Allocator* allocator) {
   CHECK(allocator);
 
   static bool v8_is_initialized = false;
   if (v8_is_initialized)
     return;
@@ skipping 34 matching lines @@
     *natives_size_out = *snapshot_size_out = 0;
     return;
   }
   *natives_data_out = reinterpret_cast<const char*>(g_mapped_natives->data());
   *snapshot_data_out = reinterpret_cast<const char*>(g_mapped_snapshot->data());
   *natives_size_out = static_cast<int>(g_mapped_natives->length());
   *snapshot_size_out = static_cast<int>(g_mapped_snapshot->length());
 }
 
 }  // namespace gin