v8_initializer.cpp

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// Copyright 2019 The PDFium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
 
#include "testing/v8_initializer.h"
 
#include <stdlib.h>
 
#include <cstring>
#include <vector>
 
#include "public/fpdfview.h"
#include "testing/utils/file_util.h"
#include "testing/utils/path_service.h"
#include "third_party/base/numerics/safe_conversions.h"
#include "v8/include/libplatform/libplatform.h"
#include "v8/include/v8-initialization.h"
#include "v8/include/v8-snapshot.h"
 
#ifdef PDF_ENABLE_XFA
#include "v8/include/cppgc/platform.h"
#endif
 
namespace {
 
#ifdef V8_USE_EXTERNAL_STARTUP_DATA
// Returns the full path for an external V8 data file based on either
// the currect exectuable path or an explicit override.
std::string GetFullPathForSnapshotFile(const std::string& exe_path,
                                       const std::string& bin_dir,
                                       const std::string& filename) {
  std::string result;
  if (!bin_dir.empty()) {
    result = bin_dir;
    if (*bin_dir.rbegin() != PATH_SEPARATOR) {
      result += PATH_SEPARATOR;
    }
  } else if (!exe_path.empty()) {
    size_t last_separator = exe_path.rfind(PATH_SEPARATOR);
    if (last_separator != std::string::npos) {
      result = exe_path.substr(0, last_separator + 1);
    }
  }
  result += filename;
  return result;
}
 
bool GetExternalData(const std::string& exe_path,
                     const std::string& bin_dir,
                     const std::string& filename,
                     v8::StartupData* result_data) {
  std::string full_path =
      GetFullPathForSnapshotFile(exe_path, bin_dir, filename);
  std::vector<uint8_t> data_buffer = GetFileContents(full_path.c_str());
  if (data_buffer.empty()) {
    return false;
  }
 
  // `result_data` takes ownership.
  void* copy = malloc(data_buffer.size());
  memcpy(copy, data_buffer.data(), data_buffer.size());
  result_data->data = static_cast<char*>(copy);
  result_data->raw_size = pdfium::base::checked_cast<int>(data_buffer.size());
  return true;
}
#endif  // V8_USE_EXTERNAL_STARTUP_DATA
 
std::unique_ptr<v8::Platform> InitializeV8Common(const std::string& exe_path,
                                                 const std::string& js_flags) {
  v8::V8::InitializeICUDefaultLocation(exe_path.c_str());
 
  std::unique_ptr<v8::Platform> platform = v8::platform::NewDefaultPlatform();
  v8::V8::InitializePlatform(platform.get());
#ifdef PDF_ENABLE_XFA
  cppgc::InitializeProcess(platform->GetPageAllocator());
#endif
 
  const char* recommended_v8_flags = FPDF_GetRecommendedV8Flags();
  v8::V8::SetFlagsFromString(recommended_v8_flags);
 
  if (!js_flags.empty())
    v8::V8::SetFlagsFromString(js_flags.c_str());
 
  // By enabling predictable mode, V8 won't post any background tasks.
  // By enabling GC, it makes it easier to chase use-after-free.
  static const char kAdditionalV8Flags[] = "--predictable --expose-gc";
  v8::V8::SetFlagsFromString(kAdditionalV8Flags);
 
  v8::V8::Initialize();
  return platform;
}
 
}  // namespace
 
#ifdef V8_USE_EXTERNAL_STARTUP_DATA
std::unique_ptr<v8::Platform> InitializeV8ForPDFiumWithStartupData(
    const std::string& exe_path,
    const std::string& js_flags,
    const std::string& bin_dir,
    v8::StartupData* snapshot_blob) {
  std::unique_ptr<v8::Platform> platform =
      InitializeV8Common(exe_path, js_flags);
  if (snapshot_blob) {
    if (!GetExternalData(exe_path, bin_dir, "snapshot_blob.bin", snapshot_blob))
      return nullptr;
    v8::V8::SetSnapshotDataBlob(snapshot_blob);
  }
  return platform;
}
#else   // V8_USE_EXTERNAL_STARTUP_DATA
std::unique_ptr<v8::Platform> InitializeV8ForPDFium(
    const std::string& exe_path,
    const std::string& js_flags) {
  return InitializeV8Common(exe_path, js_flags);
}
#endif  // V8_USE_EXTERNAL_STARTUP_DATA
 
void ShutdownV8ForPDFium() {
#ifdef PDF_ENABLE_XFA
  cppgc::ShutdownProcess();
#endif
  v8::V8::Dispose();
  v8::V8::DisposePlatform();
}