chromium_command_builder.cc

// Copyright 2014 The Chromium OS 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 "login_manager/chromium_command_builder.h"

#include <sys/resource.h>

#include <cstdarg>
#include <ctime>

#include <base/command_line.h>
#include <base/file_util.h>
#include <base/files/file_enumerator.h>
#include <base/logging.h>
#include <base/process/launch.h>
#include <base/strings/string_number_conversions.h>
#include <base/strings/string_split.h>
#include <base/strings/string_util.h>

#include "login_manager/util.h"

namespace {

// User that will run the executable.
const char kUser[] = "chronos";

// Prefix for the USE flag containing the name of the board.
const char kBoardUseFlagPrefix[] = "board_use_";

// Location where GPU debug information is bind-mounted.
const char kDebugfsGpuPath[] = "/var/run/debugfs_gpu";

// Returns the value associated with |key| in |pairs| or an empty string if the
// key isn't present. If the value is encapsulated in single or double quotes,
// they are removed.
std::string LookUpInStringPairs(const base::StringPairs& pairs,
                                const std::string& key) {
  for (size_t i = 0; i < pairs.size(); ++i) {
    if (key != pairs[i].first)
      continue;

    // Strip quotes.
    // TODO(derat): Remove quotes from Pepper .info files after
    // session_manager_setup.sh is no longer interpreting them as shell scripts.
    std::string value = pairs[i].second;
    if (value.size() >= 2U &&
        ((value[0] == '"' && value[value.size()-1] == '"') ||
         (value[0] == '\'' && value[value.size()-1] == '\'')))
      value = value.substr(1, value.size() - 2);

    return value;
  }
  return std::string();
}

// Returns true if |name| matches /^[A-Z][_A-Z0-9]+$/.
bool IsEnvironmentVariableName(const std::string& name) {
  if (name.empty() || !(name[0] >= 'A' && name[0] <= 'Z'))
    return false;
  for (size_t i = 1; i < name.size(); ++i) {
    char ch = name[i];
    if (ch != '_' && !(ch >= '0' && ch <= '9') && !(ch >= 'A' && ch <= 'Z'))
      return false;
  }
  return true;
}

}  // namespace

// TODO(derat): Rename this file to not be session-manager-specific.
const char ChromiumCommandBuilder::kUseFlagsPath[] =
    "/etc/session_manager_use_flags.txt";
const char ChromiumCommandBuilder::kLsbReleasePath[] = "/etc/lsb-release";
const char ChromiumCommandBuilder::kPepperPluginsPath[] =
    "/opt/google/chrome/pepper";
const char ChromiumCommandBuilder::kDeepMemoryProfilerPrefixPath[] =
    "/var/tmp/deep_memory_profiler_prefix.txt";
const char ChromiumCommandBuilder::kDeepMemoryProfilerTimeIntervalPath[] =
    "/var/tmp/deep_memory_profiler_time_interval.txt";

// static
bool ChromiumCommandBuilder::Run(bool log_failure,
                                 const char* command,
                                 const char* arg, ...) {
  // Extra parentheses because yay C++ most vexing parse.
  base::CommandLine cl((base::FilePath(command)));
  va_list list;
  va_start(list, arg);
  while (arg) {
    cl.AppendArg(const_cast<char*>(arg));
    arg = va_arg(list, char*);
  }
  va_end(list);

  std::string output;
  int exit_code = 0;
  if (!base::GetAppOutputWithExitCode(cl, &output, &exit_code)) {
    if (log_failure) {
      LOG(WARNING) << "\"" << cl.GetCommandLineString() << "\" failed with "
                   << exit_code << ": " << output;
    }
    return false;
  }

  return true;
}

ChromiumCommandBuilder::ChromiumCommandBuilder()
    : uid_(0),
      gid_(0),
      is_chrome_os_hardware_(false),
      is_developer_end_user_(false),
      vmodule_argument_index_(-1) {
}

ChromiumCommandBuilder::~ChromiumCommandBuilder() {}

bool ChromiumCommandBuilder::Init() {
  if (!util::GetUserInfo(kUser, &uid_, &gid_))
    return false;

  // Read the list of USE flags that were set at build time.
  std::string data;
  if (!base::ReadFileToString(GetPath(kUseFlagsPath), &data)) {
    PLOG(ERROR) << "Unable to read " << kUseFlagsPath;
    return false;
  }
  StringVector flags;
  base::SplitStringAlongWhitespace(data, &flags);
  for (size_t i = 0; i < flags.size(); ++i)
    use_flags_.insert(flags[i]);

  base::CommandLine cl(base::FilePath("crossystem"));
  cl.AppendArg("mainfw_type");
  std::string output;
  if (base::GetAppOutput(cl, &output)) {
    base::TrimWhitespace(output, base::TRIM_TRAILING, &output);
    is_chrome_os_hardware_ = (output != "nonchrome");
  }

  is_developer_end_user_ = base::GetAppOutput(
      base::CommandLine(base::FilePath("is_developer_end_user")), &output);

  return true;
}

bool ChromiumCommandBuilder::SetUpChromium() {
  AddEnvVar("USER", kUser);
  AddEnvVar("LOGNAME", kUser);
  AddEnvVar("SHELL", "/bin/sh");
  AddEnvVar("PATH", "/bin:/usr/bin");
  AddEnvVar("LC_ALL", "en_US.utf8");

  const base::FilePath data_dir(GetPath("/home").Append(kUser));
  AddEnvVar("DATA_DIR", data_dir.value());
  if (!util::EnsureDirectoryExists(data_dir, uid_, gid_, 0755))
    return false;

  // Provide /etc/lsb-release contents and timestamp so that they are available
  // to Chrome immediately without requiring a blocking file read.
  const base::FilePath lsb_path(GetPath(kLsbReleasePath));
  std::string lsb_data;
  base::File::Info info;
  if (!base::ReadFileToString(lsb_path, &lsb_data) ||
      !base::GetFileInfo(lsb_path, &info)) {
    LOG(ERROR) << "Unable to read or stat " << kLsbReleasePath;
    return false;
  }
  AddEnvVar("LSB_RELEASE", lsb_data);
  AddEnvVar("LSB_RELEASE_TIME",
            base::IntToString(info.creation_time.ToTimeT()));

  // By default, libdbus treats all warnings as fatal errors. That's too strict.
  AddEnvVar("DBUS_FATAL_WARNINGS", "0");

  // Prevent Flash asserts from crashing the plugin process.
  AddEnvVar("DONT_CRASH_ON_ASSERT", "1");

  // Increase maximum file descriptors to 2048 (default is otherwise 1024).
  // Some offline websites using IndexedDB are particularly hungry for
  // descriptors, so the default is insufficient. See crbug.com/251385.
  struct rlimit limit;
  limit.rlim_cur = limit.rlim_max = 2048;
  if (setrlimit(RLIMIT_NOFILE, &limit) < 0)
    PLOG(ERROR) << "Setting max FDs with setrlimit() failed";

  // Disable sandboxing as it causes crashes in ASAN: crbug.com/127536
  bool disable_sandbox = false;
  disable_sandbox |= SetUpASAN();
  disable_sandbox |= SetUpDeepMemoryProfiler();
  if (disable_sandbox)
    AddArg("--no-sandbox");

  SetUpPepperPlugins();
  AddUiFlags();

  AddArg("--enable-logging");
  AddArg("--log-level=1");
  AddArg("--use-cras");

  return true;
}

bool ChromiumCommandBuilder::ApplyUserConfig(const base::FilePath& path) {
  std::string data;
  if (!base::ReadFileToString(path, &data)) {
    PLOG(WARNING) << "Unable to read " << path.value();
    return false;
  }

  std::vector<std::string> lines;
  base::SplitString(data, '\n', &lines);

  for (size_t i = 0; i < lines.size(); ++i) {
    std::string line;
    base::TrimWhitespace(lines[i], base::TRIM_ALL, &line);
    if (line.empty() || line[0] == '#')
      continue;

    if (line[0] == '!' && line.size() > 1) {
      const std::string pattern = line.substr(1, line.size() - 1);
      size_t num_copied = 0;
      for (size_t src_index = 0; src_index < arguments_.size(); ++src_index) {
        if (arguments_[src_index].find(pattern) == 0) {
          // Drop the argument and shift |vmodule_argument_index_| forward if
          // the argument precedes it (or reset the index if the --vmodule flag
          // itself is being deleted).
          if (vmodule_argument_index_ > static_cast<int>(src_index))
            vmodule_argument_index_--;
          else if (vmodule_argument_index_ == static_cast<int>(src_index))
            vmodule_argument_index_ = -1;
        } else {
          arguments_[num_copied] = arguments_[src_index];
          num_copied++;
        }
      }
      arguments_.resize(num_copied);
    } else {
      base::StringPairs pairs;
      base::SplitStringIntoKeyValuePairs(line, '=', '\n', &pairs);
      if (pairs.size() == 1U && pairs[0].first == "vmodule")
        AddVmodulePattern(pairs[0].second);
      else if (pairs.size() == 1U && IsEnvironmentVariableName(pairs[0].first))
        AddEnvVar(pairs[0].first, pairs[0].second);
      else
        AddArg(line);
    }
  }

  return true;
}

bool ChromiumCommandBuilder::UseFlagIsSet(const std::string& flag) const {
  return use_flags_.count(flag) > 0;
}

bool ChromiumCommandBuilder::IsBoard(const std::string& board) const {
  return UseFlagIsSet(kBoardUseFlagPrefix + board);
}

void ChromiumCommandBuilder::AddEnvVar(const std::string& name,
                                       const std::string& value) {
  environment_variables_[name] = value;
}

std::string ChromiumCommandBuilder::ReadEnvVar(const std::string& name) const {
  StringMap::const_iterator it = environment_variables_.find(name);
  CHECK(it != environment_variables_.end()) << name << " hasn't been set";
  return it->second;
}

void ChromiumCommandBuilder::AddArg(const std::string& arg) {
  arguments_.push_back(arg);
}

void ChromiumCommandBuilder::AddVmodulePattern(const std::string& pattern) {
  if (pattern.empty())
    return;

  if (vmodule_argument_index_ < 0) {
    AddArg("--vmodule=" + pattern);
    vmodule_argument_index_ = arguments_.size() - 1;
  } else {
    arguments_[vmodule_argument_index_] += "," + pattern;
  }
}

base::FilePath ChromiumCommandBuilder::GetPath(const std::string& path) const {
  return util::GetReparentedPath(path, base_path_for_testing_);
}

bool ChromiumCommandBuilder::SetUpASAN() {
  if (!UseFlagIsSet("asan"))
    return false;

  // Make glib use system malloc.
  AddEnvVar("G_SLICE", "always-malloc");

  // Make nss use system malloc.
  AddEnvVar("NSS_DISABLE_ARENA_FREE_LIST", "1");

  // Make nss skip dlclosing dynamically loaded modules, which would result in
  // "obj:*" in backtraces.
  AddEnvVar("NSS_DISABLE_UNLOAD", "1");

  // Make ASAN output to the file because Chrome stderr is /dev/null now
  // (crbug.com/156308).
  // TODO(derat): It's weird that this lives in a Chrome directory that's
  // created by ChromeInitializer; move it somewhere else, maybe.
  AddEnvVar("ASAN_OPTIONS", "log_path=/var/log/chrome/asan_log");

  return true;
}

bool ChromiumCommandBuilder::SetUpDeepMemoryProfiler() {
  if (!UseFlagIsSet("deep_memory_profiler"))
    return false;

  // Dump heap profiles to /tmp/dmprof.*.
  std::string prefix;
  if (!base::ReadFileToString(
          GetPath(kDeepMemoryProfilerPrefixPath), &prefix)) {
    return false;
  }
  base::TrimWhitespaceASCII(prefix, base::TRIM_TRAILING, &prefix);
  AddEnvVar("HEAPPROFILE", prefix);

  // Dump every |interval| seconds.
  std::string interval;
  base::ReadFileToString(
      GetPath(kDeepMemoryProfilerTimeIntervalPath), &interval);
  base::TrimWhitespaceASCII(interval, base::TRIM_TRAILING, &interval);
  AddEnvVar("HEAP_PROFILE_TIME_INTERVAL", interval);

  // Turn on profiling mmap.
  AddEnvVar("HEAP_PROFILE_MMAP", "1");

  // Turn on Deep Memory Profiler.
  AddEnvVar("DEEP_HEAP_PROFILE", "1");

  return true;
}

void ChromiumCommandBuilder::SetUpPepperPlugins() {
  std::vector<std::string> register_plugins;

  base::FileEnumerator enumerator(GetPath(kPepperPluginsPath),
      false /* recursive */, base::FileEnumerator::FILES);
  while (true) {
    const base::FilePath path = enumerator.Next();
    if (path.empty())
      break;

    if (path.Extension() != ".info")
      continue;

    std::string data;
    if (!base::ReadFileToString(path, &data)) {
      PLOG(ERROR) << "Unable to read " << path.value();
      continue;
    }

    // .info files are full of shell junk like #-prefixed comments, so don't
    // check that SplitStringIntoKeyValuePairs() successfully parses every line.
    base::StringPairs pairs;
    base::SplitStringIntoKeyValuePairs(data, '=', '\n', &pairs);

    const std::string file_name = LookUpInStringPairs(pairs, "FILE_NAME");
    const std::string plugin_name = LookUpInStringPairs(pairs, "PLUGIN_NAME");
    const std::string version = LookUpInStringPairs(pairs, "VERSION");

    if (file_name.empty()) {
      LOG(ERROR) << "Missing FILE_NAME in " << path.value();
      continue;
    }

    if (plugin_name == "Shockwave Flash") {
      AddArg("--ppapi-flash-path=" + file_name);
      AddArg("--ppapi-flash-version=" + version);

      // TODO(ihf): Remove once crbug.com/237380 and crbug.com/276738 are fixed.
      const bool is_atom = IsBoard("x86-alex") || IsBoard("x86-alex_he") ||
          IsBoard("x86-mario") || IsBoard("x86-zgb") || IsBoard("x86-zgb_he");
      AddArg("--ppapi-flash-args=enable_hw_video_decode=" +
             std::string(is_atom ? "0" : "1"));
    } else {
      const std::string description = LookUpInStringPairs(pairs, "DESCRIPTION");
      const std::string mime_types = LookUpInStringPairs(pairs, "MIME_TYPES");

      std::string plugin_string = file_name;
      if (!plugin_name.empty()) {
        plugin_string += "#" + plugin_name;
        if (!description.empty()) {
          plugin_string += "#" + description;
          if (!version.empty()) {
            plugin_string += "#" + version;
          }
        }
      }
      plugin_string += ";" + mime_types;
      register_plugins.push_back(plugin_string);
    }
  }

  if (!register_plugins.empty()) {
    std::sort(register_plugins.begin(), register_plugins.end());
    AddArg("--register-pepper-plugins=" + JoinString(register_plugins, ","));
  }
}

void ChromiumCommandBuilder::AddUiFlags() {
  AddArg("--enable-fixed-position-compositing");
  AddArg("--enable-impl-side-painting");
  AddArg("--max-tiles-for-interest-area=512");
  AddArg("--ui-enable-per-tile-painting");
  AddArg("--ui-prioritize-in-gpu-process");

  if (UseFlagIsSet("egl"))
    AddArg("--use-gl=egl");

  // On boards with ARM NEON support, force libvpx to use the NEON-optimized
  // code paths. Remove once http://crbug.com/161834 is fixed.
  // This is needed because libvpx cannot check cpuinfo within the sandbox.
  if (UseFlagIsSet("exynos"))
    AddEnvVar("VPX_SIMD_CAPS", "0xf");

  if (UseFlagIsSet("highdpi")) {
    AddArg("--enable-webkit-text-subpixel-positioning");
    AddArg("--enable-accelerated-overflow-scroll");
    AddArg("--default-tile-width=512");
    AddArg("--default-tile-height=512");
  }

  if (IsBoard("link"))
    AddArg("--touch-calibration=0,0,0,50");

  AddArg(std::string("--gpu-sandbox-failures-fatal=") +
      (is_chrome_os_hardware() ? "yes" : "no"));

  if (UseFlagIsSet("gpu_sandbox_allow_sysv_shm"))
    AddArg("--gpu-sandbox-allow-sysv-shm");

  if (UseFlagIsSet("gpu_sandbox_start_after_initialization"))
    AddArg("--gpu-sandbox-start-after-initialization");

  if (IsBoard("peach_pit") || IsBoard("peach_pi") || IsBoard("nyan") ||
      IsBoard("nyan_big") || IsBoard("nyan_blaze"))
    AddArg("--enable-webrtc-hw-vp8-encoding");

  if (IsBoard("peach_pi"))
    AddArg("--ignore-resolution-limits-for-accelerated-video-decode");

  // Ozone platform configuration.
  if (UseFlagIsSet("ozone_platform_dri")) {
    // TODO(spang): Use freon/chromeos platform, not DRI example platform.
    AddArg("--ozone-platform=dri");

    // TODO(spang): Fix hardware acceleration.
    AddArg("--disable-gpu");
    AddArg("--ui-disable-threaded-compositing");
  }

  // Allow Chrome to access GPU memory information despite /sys/kernel/debug
  // being owned by debugd. This limits the security attack surface versus
  // leaving the whole debug directory world-readable: http://crbug.com/175828
  // (Only do this if we're running as root, i.e. not in a test.)
  const base::FilePath debugfs_gpu_path(GetPath(kDebugfsGpuPath));
  if (getuid() == 0 && !base::DirectoryExists(debugfs_gpu_path)) {
    if (base::CreateDirectory(debugfs_gpu_path)) {
      Run(true, "mount", "-o", "bind", "/sys/kernel/debug/dri/0",
          kDebugfsGpuPath, NULL);
    } else {
      PLOG(ERROR) << "Unable to create " << kDebugfsGpuPath;
    }
  }
}