// Copyright 2015 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 "android_webview/common/crash_reporter/aw_crash_reporter_client.h"

#include <random>

#include "android_webview/common/aw_descriptors.h"
#include "android_webview/common/aw_paths.h"
#include "android_webview/common/crash_reporter/crash_keys.h"
#include "base/android/build_info.h"
#include "base/base_paths_android.h"
#include "base/debug/crash_logging.h"
#include "base/debug/dump_without_crashing.h"
#include "base/files/file_path.h"
#include "base/lazy_instance.h"
#include "base/path_service.h"
#include "base/scoped_native_library.h"
#include "base/synchronization/lock.h"
#include "base/time/time.h"
#include "build/build_config.h"
#include "components/crash/content/app/breakpad_linux.h"
#include "components/crash/content/app/crash_reporter_client.h"
#include "components/version_info/version_info_values.h"
#include "content/public/common/content_switches.h"

namespace android_webview {
namespace crash_reporter {

namespace {

// TODO(gsennton) lower the following value before pushing to stable:
const double minidump_generation_user_fraction = 1.0;

// Returns whether the current process should be reporting crashes through
// minidumps. This function should only be called once per process - the return
// value might differ between different calls to this function.
bool is_process_in_crash_reporting_sample() {
  // TODO(gsennton): update this method to depend on finch when that is
  // implemented for WebView.
  base::Time cur_time = base::Time::Now();
  std::minstd_rand generator(cur_time.ToInternalValue() /* seed */);
  std::uniform_real_distribution<double> distribution(0.0, 1.0);
  return minidump_generation_user_fraction > distribution(generator);
}

class AwCrashReporterClient : public ::crash_reporter::CrashReporterClient {
 public:
  AwCrashReporterClient()
      : dump_fd_(kAndroidMinidumpDescriptor),
        crash_signal_fd_(-1),
        in_crash_reporting_sample_(is_process_in_crash_reporting_sample()) {}

  // Does not use lock, can only be called immediately after creation.
  void set_crash_signal_fd(int fd) { crash_signal_fd_ = fd; }

  // crash_reporter::CrashReporterClient implementation.
  bool UseCrashKeysWhiteList() override { return true; }
  const char* const* GetCrashKeyWhiteList() override;

  bool IsRunningUnattended() override { return false; }
  bool GetCollectStatsConsent() override;
  void GetProductNameAndVersion(const char** product_name,
                                const char** version) override {
    *product_name = "AndroidWebView";
    *version = PRODUCT_VERSION;
  }
  // Microdumps are always enabled in WebView builds, conversely to what happens
  // in the case of the other Chrome for Android builds (where they are enabled
  // only when NO_UNWIND_TABLES == 1).
  bool ShouldEnableBreakpadMicrodumps() override { return true; }

  int GetAndroidMinidumpDescriptor() override { return dump_fd_; }
  int GetAndroidCrashSignalFD() override { return crash_signal_fd_; }

  bool DumpWithoutCrashingToFd(int fd) {
    // TODO(tobiasjs): figure out what to do with on demand minidump on the
    // renderer process of webview.
    breakpad::GenerateMinidumpOnDemandForAndroid(fd);
    return true;
  }

  bool GetCrashDumpLocation(base::FilePath* crash_dir) override {
    return base::PathService::Get(android_webview::DIR_CRASH_DUMPS, crash_dir);
  }

 private:
  int dump_fd_;
  int crash_signal_fd_;
  bool in_crash_reporting_sample_;
  DISALLOW_COPY_AND_ASSIGN(AwCrashReporterClient);
};

const char* const* AwCrashReporterClient::GetCrashKeyWhiteList() {
  return crash_keys::kWebViewCrashKeyWhiteList;
}

bool AwCrashReporterClient::GetCollectStatsConsent() {
#if defined(GOOGLE_CHROME_BUILD)
  // TODO(gsennton): Enabling minidump-generation unconditionally means we
  // will generate minidumps even if the user doesn't consent to minidump
  // uploads. However, we will check user-consent before uploading any
  // minidumps, if we do not have user consent we will delete the minidumps.
  // We should investigate whether we can avoid generating minidumps
  // altogether if we don't have user consent, see crbug.com/692485
  return in_crash_reporting_sample_;
#else
  return false;
#endif  // !defined(GOOGLE_CHROME_BUILD)
}

base::LazyInstance<AwCrashReporterClient>::Leaky g_crash_reporter_client =
    LAZY_INSTANCE_INITIALIZER;

bool g_enabled = false;

#if defined(ARCH_CPU_X86_FAMILY)
bool SafeToUseSignalHandler() {
  // N+ shared library namespacing means that we are unable to dlopen
  // libnativebridge (because it isn't in the NDK). However we know
  // that, were we able to, the tests below would pass, so just return
  // true here.
  if (base::android::BuildInfo::GetInstance()->sdk_int() >=
      base::android::SDK_VERSION_NOUGAT) {
    return true;
  }
  // On X86/64 there are binary translators that handle SIGSEGV in userspace and
  // may get chained after our handler - see http://crbug.com/477444
  // We attempt to detect this to work out when it's safe to install breakpad.
  // If anything doesn't seem right we assume it's not safe.

  // type and mangled name of android::NativeBridgeInitialized
  typedef bool (*InitializedFunc)();
  const char kInitializedSymbol[] = "_ZN7android23NativeBridgeInitializedEv";
  // type and mangled name of android::NativeBridgeGetVersion
  typedef uint32_t (*VersionFunc)();
  const char kVersionSymbol[] = "_ZN7android22NativeBridgeGetVersionEv";

  base::ScopedNativeLibrary lib_native_bridge(
      base::FilePath("libnativebridge.so"));
  if (!lib_native_bridge.is_valid()) {
    DLOG(WARNING) << "Couldn't load libnativebridge";
    return false;
  }

  InitializedFunc NativeBridgeInitialized = reinterpret_cast<InitializedFunc>(
      lib_native_bridge.GetFunctionPointer(kInitializedSymbol));
  if (NativeBridgeInitialized == nullptr) {
    DLOG(WARNING) << "Couldn't tell if native bridge initialized";
    return false;
  }
  if (!NativeBridgeInitialized()) {
    // Native process, safe to use breakpad.
    return true;
  }

  VersionFunc NativeBridgeGetVersion = reinterpret_cast<VersionFunc>(
      lib_native_bridge.GetFunctionPointer(kVersionSymbol));
  if (NativeBridgeGetVersion == nullptr) {
    DLOG(WARNING) << "Couldn't get native bridge version";
    return false;
  }
  uint32_t version = NativeBridgeGetVersion();
  if (version >= 2) {
    // Native bridge at least version 2, safe to use breakpad.
    return true;
  } else {
    DLOG(WARNING) << "Native bridge ver=" << version << "; too low";
    return false;
  }
}
#endif

}  // namespace

void EnableCrashReporter(const std::string& process_type, int crash_signal_fd) {
  if (g_enabled) {
    NOTREACHED() << "EnableCrashReporter called more than once";
    return;
  }

#if defined(ARCH_CPU_X86_FAMILY)
  if (!SafeToUseSignalHandler()) {
    LOG(WARNING) << "Can't use breakpad to handle WebView crashes";
    return;
  }
#endif

  AwCrashReporterClient* client = g_crash_reporter_client.Pointer();
  if (process_type == switches::kRendererProcess && crash_signal_fd != -1) {
    client->set_crash_signal_fd(crash_signal_fd);
  }
  ::crash_reporter::SetCrashReporterClient(client);
  breakpad::SanitizationInfo sanitization_info;
  sanitization_info.should_sanitize_dumps = true;
#if !defined(COMPONENT_BUILD)
  sanitization_info.skip_dump_if_principal_mapping_not_referenced = true;
  sanitization_info.address_within_principal_mapping =
      reinterpret_cast<uintptr_t>(&EnableCrashReporter);
#endif  // defined(COMPONENT_BUILD)

  bool is_browser_process =
      process_type.empty() ||
      process_type == breakpad::kWebViewSingleProcessType ||
      process_type == breakpad::kBrowserProcessType;
  if (is_browser_process) {
    breakpad::InitCrashReporter(process_type, sanitization_info);
  } else {
    breakpad::InitNonBrowserCrashReporterForAndroid(process_type,
                                                    sanitization_info);
  }
  g_enabled = true;
}

bool GetCrashDumpLocation(base::FilePath* crash_dir) {
  return g_crash_reporter_client.Get().GetCrashDumpLocation(crash_dir);
}

void AddGpuFingerprintToMicrodumpCrashHandler(
    const std::string& gpu_fingerprint) {
  breakpad::AddGpuFingerprintToMicrodumpCrashHandler(gpu_fingerprint);
}

bool DumpWithoutCrashingToFd(int fd) {
  ::crash_reporter::SetCrashReporterClient(g_crash_reporter_client.Pointer());
  return g_crash_reporter_client.Pointer()->DumpWithoutCrashingToFd(fd);
}

bool IsCrashReporterEnabled() {
  return breakpad::IsCrashReporterEnabled();
}

void SuppressDumpGeneration() {
  breakpad::SuppressDumpGeneration();
}

}  // namespace crash_reporter
}  // namespace android_webview