#!/usr/bin/env python
# Copyright 2016 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
################################################################################
"""Helper script for OSS-Fuzz users. Can do common tasks like building
projects/fuzzers, running them etc."""

from __future__ import print_function
from multiprocessing.dummy import Pool as ThreadPool
import argparse
import datetime
import errno
import logging
import os
import pipes
import re
import subprocess
import sys
import templates

import constants

OSS_FUZZ_DIR = os.path.dirname(os.path.dirname(os.path.realpath(__file__)))
BUILD_DIR = os.path.join(OSS_FUZZ_DIR, 'build')

BASE_RUNNER_IMAGE = 'gcr.io/oss-fuzz-base/base-runner'

BASE_IMAGES = {
    'generic': [
        'gcr.io/oss-fuzz-base/base-image',
        'gcr.io/oss-fuzz-base/base-clang',
        'gcr.io/oss-fuzz-base/base-builder',
        BASE_RUNNER_IMAGE,
        'gcr.io/oss-fuzz-base/base-runner-debug',
    ],
    'go': ['gcr.io/oss-fuzz-base/base-builder-go'],
    'jvm': ['gcr.io/oss-fuzz-base/base-builder-jvm'],
    'python': ['gcr.io/oss-fuzz-base/base-builder-python'],
    'rust': ['gcr.io/oss-fuzz-base/base-builder-rust'],
    'swift': ['gcr.io/oss-fuzz-base/base-builder-swift'],
}

VALID_PROJECT_NAME_REGEX = re.compile(r'^[a-zA-Z0-9_-]+$')
MAX_PROJECT_NAME_LENGTH = 26

CORPUS_URL_FORMAT = (
    'gs://{project_name}-corpus.clusterfuzz-external.appspot.com/libFuzzer/'
    '{fuzz_target}/')
CORPUS_BACKUP_URL_FORMAT = (
    'gs://{project_name}-backup.clusterfuzz-external.appspot.com/corpus/'
    'libFuzzer/{fuzz_target}/')

LANGUAGE_REGEX = re.compile(r'[^\s]+')
PROJECT_LANGUAGE_REGEX = re.compile(r'\s*language\s*:\s*([^\s]+)')

WORKDIR_REGEX = re.compile(r'\s*WORKDIR\s*([^\s]+)')

LANGUAGES_WITH_BUILDER_IMAGES = {'go', 'jvm', 'python', 'rust', 'swift'}

if sys.version_info[0] >= 3:
  raw_input = input  # pylint: disable=invalid-name

# pylint: disable=too-many-lines


class Project:
  """Class representing a project that is in OSS-Fuzz or an external project
  (ClusterFuzzLite user)."""

  def __init__(
      self,
      project_name_or_path,
      is_external=False,
      build_integration_path=constants.DEFAULT_EXTERNAL_BUILD_INTEGRATION_PATH):
    self.is_external = is_external
    if self.is_external:
      self.path = os.path.abspath(project_name_or_path)
      self.name = os.path.basename(self.path)
      self.build_integration_path = os.path.join(self.path,
                                                 build_integration_path)
    else:
      self.name = project_name_or_path
      self.path = os.path.join(OSS_FUZZ_DIR, 'projects', self.name)
      self.build_integration_path = self.path

  @property
  def dockerfile_path(self):
    """Returns path to the project Dockerfile."""
    return os.path.join(self.build_integration_path, 'Dockerfile')

  @property
  def language(self):
    """Returns project language."""
    if self.is_external:
      # TODO(metzman): Handle this properly.
      return constants.DEFAULT_LANGUAGE

    project_yaml_path = os.path.join(self.path, 'project.yaml')
    with open(project_yaml_path) as file_handle:
      content = file_handle.read()
      for line in content.splitlines():
        match = PROJECT_LANGUAGE_REGEX.match(line)
        if match:
          return match.group(1)

    logging.warning('Language not specified in project.yaml.')
    return None

  @property
  def out(self):
    """Returns the out dir for the project. Creates it if needed."""
    return _get_out_dir(self.name)

  @property
  def work(self):
    """Returns the out dir for the project. Creates it if needed."""
    return _get_project_build_subdir(self.name, 'work')

  @property
  def corpus(self):
    """Returns the out dir for the project. Creates it if needed."""
    return _get_project_build_subdir(self.name, 'corpus')


def main():  # pylint: disable=too-many-branches,too-many-return-statements
  """Gets subcommand from program arguments and does it. Returns 0 on success 1
  on error."""
  logging.basicConfig(level=logging.INFO)

  parser = get_parser()
  args = parse_args(parser)

  # Note: this has to happen after parse_args above as parse_args needs to know
  # the original CWD for external projects.
  os.chdir(OSS_FUZZ_DIR)
  if not os.path.exists(BUILD_DIR):
    os.mkdir(BUILD_DIR)

  # We have different default values for `sanitizer` depending on the `engine`.
  # Some commands do not have `sanitizer` argument, so `hasattr` is necessary.
  if hasattr(args, 'sanitizer') and not args.sanitizer:
    if args.engine == 'dataflow':
      args.sanitizer = 'dataflow'
    else:
      args.sanitizer = constants.DEFAULT_SANITIZER

  if args.command == 'generate':
    result = generate(args)
  elif args.command == 'build_image':
    result = build_image(args)
  elif args.command == 'build_fuzzers':
    result = build_fuzzers(args)
  elif args.command == 'check_build':
    result = check_build(args)
  elif args.command == 'download_corpora':
    result = download_corpora(args)
  elif args.command == 'run_fuzzer':
    result = run_fuzzer(args)
  elif args.command == 'coverage':
    result = coverage(args)
  elif args.command == 'reproduce':
    result = reproduce(args)
  elif args.command == 'shell':
    result = shell(args)
  elif args.command == 'pull_images':
    result = pull_images()
  else:
    # Print help string if no arguments provided.
    parser.print_help()
    result = False
  return bool_to_retcode(result)


def bool_to_retcode(boolean):
  """Returns 0 if |boolean| is Truthy, 0 is the standard return code for a
  successful process execution. Returns 1 otherwise, indicating the process
  failed."""
  return 0 if boolean else 1


def parse_args(parser, args=None):
  """Parses |args| using |parser| and returns parsed args. Also changes
  |args.build_integration_path| to have correct default behavior."""
  # Use default argument None for args so that in production, argparse does its
  # normal behavior, but unittesting is easier.
  parsed_args = parser.parse_args(args)
  project = getattr(parsed_args, 'project', None)
  if not project:
    return parsed_args

  # Use hacky method for extracting attributes so that ShellTest works.
  # TODO(metzman): Fix this.
  is_external = getattr(parsed_args, 'external', False)
  parsed_args.project = Project(parsed_args.project, is_external)
  return parsed_args


def _add_external_project_args(parser):
  parser.add_argument(
      '--external',
      help='Is project external?',
      default=False,
      action='store_true',
  )


def get_parser():  # pylint: disable=too-many-statements
  """Returns an argparse parser."""
  parser = argparse.ArgumentParser('helper.py', description='oss-fuzz helpers')
  subparsers = parser.add_subparsers(dest='command')

  generate_parser = subparsers.add_parser(
      'generate', help='Generate files for new project.')
  generate_parser.add_argument('project')
  generate_parser.add_argument(
      '--language',
      default=constants.DEFAULT_LANGUAGE,
      choices=['c', 'c++', 'rust', 'go', 'jvm', 'swift', 'python'],
      help='Project language.')
  _add_external_project_args(generate_parser)

  build_image_parser = subparsers.add_parser('build_image',
                                             help='Build an image.')
  build_image_parser.add_argument('project')
  build_image_parser.add_argument('--pull',
                                  action='store_true',
                                  help='Pull latest base image.')
  build_image_parser.add_argument('--cache',
                                  action='store_true',
                                  default=False,
                                  help='Use docker cache when building image.')
  build_image_parser.add_argument('--no-pull',
                                  action='store_true',
                                  help='Do not pull latest base image.')
  _add_external_project_args(build_image_parser)

  build_fuzzers_parser = subparsers.add_parser(
      'build_fuzzers', help='Build fuzzers for a project.')
  _add_architecture_args(build_fuzzers_parser)
  _add_engine_args(build_fuzzers_parser)
  _add_sanitizer_args(build_fuzzers_parser)
  _add_environment_args(build_fuzzers_parser)
  _add_external_project_args(build_fuzzers_parser)
  build_fuzzers_parser.add_argument('project')
  build_fuzzers_parser.add_argument('source_path',
                                    help='path of local source',
                                    nargs='?')
  build_fuzzers_parser.add_argument('--mount_path',
                                    dest='mount_path',
                                    help='path to mount local source in '
                                    '(defaults to WORKDIR)')
  build_fuzzers_parser.add_argument('--clean',
                                    dest='clean',
                                    action='store_true',
                                    help='clean existing artifacts.')
  build_fuzzers_parser.add_argument('--no-clean',
                                    dest='clean',
                                    action='store_false',
                                    help='do not clean existing artifacts '
                                    '(default).')
  build_fuzzers_parser.set_defaults(clean=False)

  check_build_parser = subparsers.add_parser(
      'check_build', help='Checks that fuzzers execute without errors.')
  _add_architecture_args(check_build_parser)
  _add_engine_args(check_build_parser, choices=constants.ENGINES)
  _add_sanitizer_args(check_build_parser, choices=constants.SANITIZERS)
  _add_environment_args(check_build_parser)
  check_build_parser.add_argument('project',
                                  help='name of the project or path (external)')
  check_build_parser.add_argument('fuzzer_name',
                                  help='name of the fuzzer',
                                  nargs='?')
  _add_external_project_args(check_build_parser)

  run_fuzzer_parser = subparsers.add_parser(
      'run_fuzzer', help='Run a fuzzer in the emulated fuzzing environment.')
  _add_engine_args(run_fuzzer_parser)
  _add_sanitizer_args(run_fuzzer_parser)
  _add_environment_args(run_fuzzer_parser)
  _add_external_project_args(run_fuzzer_parser)
  run_fuzzer_parser.add_argument(
      '--corpus-dir', help='directory to store corpus for the fuzz target')
  run_fuzzer_parser.add_argument('project',
                                 help='name of the project or path (external)')
  run_fuzzer_parser.add_argument('fuzzer_name', help='name of the fuzzer')
  run_fuzzer_parser.add_argument('fuzzer_args',
                                 help='arguments to pass to the fuzzer',
                                 nargs=argparse.REMAINDER)

  coverage_parser = subparsers.add_parser(
      'coverage', help='Generate code coverage report for the project.')
  coverage_parser.add_argument('--no-corpus-download',
                               action='store_true',
                               help='do not download corpus backup from '
                               'OSS-Fuzz; use corpus located in '
                               'build/corpus/<project>/<fuzz_target>/')
  coverage_parser.add_argument('--port',
                               default='8008',
                               help='specify port for'
                               ' a local HTTP server rendering coverage report')
  coverage_parser.add_argument('--fuzz-target',
                               help='specify name of a fuzz '
                               'target to be run for generating coverage '
                               'report')
  coverage_parser.add_argument('--corpus-dir',
                               help='specify location of corpus'
                               ' to be used (requires --fuzz-target argument)')
  coverage_parser.add_argument('project',
                               help='name of the project or path (external)')
  coverage_parser.add_argument('extra_args',
                               help='additional arguments to '
                               'pass to llvm-cov utility.',
                               nargs='*')
  _add_external_project_args(coverage_parser)

  download_corpora_parser = subparsers.add_parser(
      'download_corpora', help='Download all corpora for a project.')
  download_corpora_parser.add_argument('--fuzz-target',
                                       help='specify name of a fuzz target')
  download_corpora_parser.add_argument(
      'project', help='name of the project or path (external)')

  reproduce_parser = subparsers.add_parser('reproduce',
                                           help='Reproduce a crash.')
  reproduce_parser.add_argument('--valgrind',
                                action='store_true',
                                help='run with valgrind')
  reproduce_parser.add_argument('project',
                                help='name of the project or path (external)')
  reproduce_parser.add_argument('fuzzer_name', help='name of the fuzzer')
  reproduce_parser.add_argument('testcase_path', help='path of local testcase')
  reproduce_parser.add_argument('fuzzer_args',
                                help='arguments to pass to the fuzzer',
                                nargs=argparse.REMAINDER)
  _add_environment_args(reproduce_parser)
  _add_external_project_args(reproduce_parser)

  shell_parser = subparsers.add_parser(
      'shell', help='Run /bin/bash within the builder container.')
  shell_parser.add_argument('project',
                            help='name of the project or path (external)')
  shell_parser.add_argument('source_path',
                            help='path of local source',
                            nargs='?')
  _add_architecture_args(shell_parser)
  _add_engine_args(shell_parser)
  _add_sanitizer_args(shell_parser)
  _add_environment_args(shell_parser)
  _add_external_project_args(shell_parser)

  subparsers.add_parser('pull_images', help='Pull base images.')
  return parser


def is_base_image(image_name):
  """Checks if the image name is a base image."""
  return os.path.exists(os.path.join('infra', 'base-images', image_name))


def check_project_exists(project):
  """Checks if a project exists."""
  if os.path.exists(project.path):
    return True

  if project.is_external:
    descriptive_project_name = project.path
  else:
    descriptive_project_name = project.name

  logging.error('"%s" does not exist.', descriptive_project_name)
  return False


def _check_fuzzer_exists(project, fuzzer_name):
  """Checks if a fuzzer exists."""
  command = ['docker', 'run', '--rm']
  command.extend(['-v', '%s:/out' % project.out])
  command.append(BASE_RUNNER_IMAGE)

  command.extend(['/bin/bash', '-c', 'test -f /out/%s' % fuzzer_name])

  try:
    subprocess.check_call(command)
  except subprocess.CalledProcessError:
    logging.error('%s does not seem to exist. Please run build_fuzzers first.',
                  fuzzer_name)
    return False

  return True


def _get_absolute_path(path):
  """Returns absolute path with user expansion."""
  return os.path.abspath(os.path.expanduser(path))


def _get_command_string(command):
  """Returns a shell escaped command string."""
  return ' '.join(pipes.quote(part) for part in command)


def _get_project_build_subdir(project, subdir_name):
  """Creates the |subdir_name| subdirectory of the |project| subdirectory in
  |BUILD_DIR| and returns its path."""
  directory = os.path.join(BUILD_DIR, subdir_name, project)
  if not os.path.exists(directory):
    os.makedirs(directory)

  return directory


def _get_out_dir(project=''):
  """Creates and returns path to /out directory for the given project (if
  specified)."""
  return _get_project_build_subdir(project, 'out')


def _add_architecture_args(parser, choices=None):
  """Adds common architecture args."""
  if choices is None:
    choices = constants.ARCHITECTURES
  parser.add_argument('--architecture',
                      default=constants.DEFAULT_ARCHITECTURE,
                      choices=choices)


def _add_engine_args(parser, choices=None):
  """Adds common engine args."""
  if choices is None:
    choices = constants.ENGINES
  parser.add_argument('--engine',
                      default=constants.DEFAULT_ENGINE,
                      choices=choices)


def _add_sanitizer_args(parser, choices=None):
  """Adds common sanitizer args."""
  if choices is None:
    choices = constants.SANITIZERS
  parser.add_argument(
      '--sanitizer',
      default=None,
      choices=choices,
      help='the default is "address"; "dataflow" for "dataflow" engine')


def _add_environment_args(parser):
  """Adds common environment args."""
  parser.add_argument('-e',
                      action='append',
                      help="set environment variable e.g. VAR=value")


def build_image_impl(project, cache=True, pull=False):
  """Builds image."""
  image_name = project.name

  if is_base_image(image_name):
    image_project = 'oss-fuzz-base'
    docker_build_dir = os.path.join(OSS_FUZZ_DIR, 'infra', 'base-images',
                                    image_name)
    dockerfile_path = os.path.join(docker_build_dir, 'Dockerfile')
  else:
    if not check_project_exists(project):
      return False
    dockerfile_path = project.dockerfile_path
    docker_build_dir = project.path
    image_project = 'oss-fuzz'

  if pull and not pull_images(project.language):
    return False

  build_args = []
  if not cache:
    build_args.append('--no-cache')

  build_args += [
      '-t',
      'gcr.io/%s/%s' % (image_project, image_name), '--file', dockerfile_path
  ]
  build_args.append(docker_build_dir)
  return docker_build(build_args)


def _env_to_docker_args(env_list):
  """Turns envirnoment variable list into docker arguments."""
  return sum([['-e', v] for v in env_list], [])


def workdir_from_lines(lines, default='/src'):
  """Gets the WORKDIR from the given lines."""
  for line in reversed(lines):  # reversed to get last WORKDIR.
    match = re.match(WORKDIR_REGEX, line)
    if match:
      workdir = match.group(1)
      workdir = workdir.replace('$SRC', '/src')

      if not os.path.isabs(workdir):
        workdir = os.path.join('/src', workdir)

      return os.path.normpath(workdir)

  return default


def _workdir_from_dockerfile(project):
  """Parses WORKDIR from the Dockerfile for the given project."""
  with open(project.dockerfile_path) as file_handle:
    lines = file_handle.readlines()

  return workdir_from_lines(lines, default=os.path.join('/src', project.name))


def docker_run(run_args, print_output=True):
  """Calls `docker run`."""
  command = ['docker', 'run', '--rm', '--privileged']

  # Support environments with a TTY.
  if sys.stdin.isatty():
    command.append('-i')

  command.extend(run_args)

  logging.info('Running: %s.', _get_command_string(command))
  stdout = None
  if not print_output:
    stdout = open(os.devnull, 'w')

  try:
    subprocess.check_call(command, stdout=stdout, stderr=subprocess.STDOUT)
  except subprocess.CalledProcessError:
    return False

  return True


def docker_build(build_args):
  """Calls `docker build`."""
  command = ['docker', 'build']
  command.extend(build_args)
  logging.info('Running: %s.', _get_command_string(command))

  try:
    subprocess.check_call(command)
  except subprocess.CalledProcessError:
    logging.error('Docker build failed.')
    return False

  return True


def docker_pull(image):
  """Call `docker pull`."""
  command = ['docker', 'pull', image]
  logging.info('Running: %s', _get_command_string(command))

  try:
    subprocess.check_call(command)
  except subprocess.CalledProcessError:
    logging.error('Docker pull failed.')
    return False

  return True


def build_image(args):
  """Builds docker image."""
  if args.pull and args.no_pull:
    logging.error('Incompatible arguments --pull and --no-pull.')
    return False

  if args.pull:
    pull = True
  elif args.no_pull:
    pull = False
  else:
    y_or_n = raw_input('Pull latest base images (compiler/runtime)? (y/N): ')
    pull = y_or_n.lower() == 'y'

  if pull:
    logging.info('Pulling latest base images...')
  else:
    logging.info('Using cached base images...')

  # If build_image is called explicitly, don't use cache.
  if build_image_impl(args.project, cache=args.cache, pull=pull):
    return True

  return False


def build_fuzzers_impl(  # pylint: disable=too-many-arguments,too-many-locals,too-many-branches
    project,
    clean,
    engine,
    sanitizer,
    architecture,
    env_to_add,
    source_path,
    mount_path=None):
  """Builds fuzzers."""
  if not build_image_impl(project):
    return False

  if clean:
    logging.info('Cleaning existing build artifacts.')

    # Clean old and possibly conflicting artifacts in project's out directory.
    docker_run([
        '-v',
        '%s:/out' % project.out, '-t',
        'gcr.io/oss-fuzz/%s' % project.name, '/bin/bash', '-c', 'rm -rf /out/*'
    ])

    docker_run([
        '-v',
        '%s:/work' % project.work, '-t',
        'gcr.io/oss-fuzz/%s' % project.name, '/bin/bash', '-c', 'rm -rf /work/*'
    ])

  else:
    logging.info('Keeping existing build artifacts as-is (if any).')
  env = [
      'FUZZING_ENGINE=' + engine,
      'SANITIZER=' + sanitizer,
      'ARCHITECTURE=' + architecture,
  ]

  _add_oss_fuzz_ci_if_needed(env)

  if project.language:
    env.append('FUZZING_LANGUAGE=' + project.language)

  if env_to_add:
    env += env_to_add

  command = ['--cap-add', 'SYS_PTRACE'] + _env_to_docker_args(env)
  if source_path:
    workdir = _workdir_from_dockerfile(project)
    if mount_path:
      command += [
          '-v',
          '%s:%s' % (_get_absolute_path(source_path), mount_path),
      ]
    else:
      if workdir == '/src':
        logging.error('Cannot use local checkout with "WORKDIR: /src".')
        return False

      command += [
          '-v',
          '%s:%s' % (_get_absolute_path(source_path), workdir),
      ]

  command += [
      '-v',
      '%s:/out' % project.out, '-v',
      '%s:/work' % project.work, '-t',
      'gcr.io/oss-fuzz/%s' % project.name
  ]

  result = docker_run(command)
  if not result:
    logging.error('Building fuzzers failed.')
    return False

  return True


def build_fuzzers(args):
  """Builds fuzzers."""
  return build_fuzzers_impl(args.project,
                            args.clean,
                            args.engine,
                            args.sanitizer,
                            args.architecture,
                            args.e,
                            args.source_path,
                            mount_path=args.mount_path)


def _add_oss_fuzz_ci_if_needed(env):
  """Adds value of |OSS_FUZZ_CI| environment variable to |env| if it is set."""
  oss_fuzz_ci = os.getenv('OSS_FUZZ_CI')
  if oss_fuzz_ci:
    env.append('OSS_FUZZ_CI=' + oss_fuzz_ci)


def check_build(args):
  """Checks that fuzzers in the container execute without errors."""
  if not check_project_exists(args.project):
    return False

  if (args.fuzzer_name and
      not _check_fuzzer_exists(args.project, args.fuzzer_name)):
    return False

  fuzzing_language = args.project.language
  if not fuzzing_language:
    fuzzing_language = constants.DEFAULT_LANGUAGE
    logging.warning('Language not specified in project.yaml. Defaulting to %s.',
                    fuzzing_language)

  env = [
      'FUZZING_ENGINE=' + args.engine,
      'SANITIZER=' + args.sanitizer,
      'ARCHITECTURE=' + args.architecture,
      'FUZZING_LANGUAGE=' + fuzzing_language,
  ]
  _add_oss_fuzz_ci_if_needed(env)
  if args.e:
    env += args.e

  run_args = _env_to_docker_args(env) + [
      '-v', '%s:/out' % args.project.out, '-t', BASE_RUNNER_IMAGE
  ]

  if args.fuzzer_name:
    run_args += ['test_one.py', args.fuzzer_name]
  else:
    run_args.append('test_all.py')

  result = docker_run(run_args)
  if result:
    logging.info('Check build passed.')
  else:
    logging.error('Check build failed.')

  return result


def _get_fuzz_targets(project):
  """Returns names of fuzz targest build in the project's /out directory."""
  fuzz_targets = []
  for name in os.listdir(project.out):
    if name.startswith('afl-'):
      continue
    if name.startswith('jazzer_'):
      continue
    if name == 'llvm-symbolizer':
      continue

    path = os.path.join(project.out, name)
    # Python and JVM fuzz targets are only executable for the root user, so
    # we can't use os.access.
    if os.path.isfile(path) and (os.stat(path).st_mode & 0o111):
      fuzz_targets.append(name)

  return fuzz_targets


def _get_latest_corpus(project, fuzz_target, base_corpus_dir):
  """Downloads the latest corpus for the given fuzz target."""
  corpus_dir = os.path.join(base_corpus_dir, fuzz_target)
  if not os.path.exists(corpus_dir):
    os.makedirs(corpus_dir)

  if not fuzz_target.startswith(project.name + '_'):
    fuzz_target = '%s_%s' % (project.name, fuzz_target)

  corpus_backup_url = CORPUS_BACKUP_URL_FORMAT.format(project_name=project.name,
                                                      fuzz_target=fuzz_target)
  command = ['gsutil', 'ls', corpus_backup_url]

  # Don't capture stderr. We want it to print in real time, in case gsutil is
  # asking for two-factor authentication.
  corpus_listing = subprocess.Popen(command, stdout=subprocess.PIPE)
  output, _ = corpus_listing.communicate()

  # Some fuzz targets (e.g. new ones) may not have corpus yet, just skip those.
  if corpus_listing.returncode:
    logging.warning('Corpus for %s not found:\n', fuzz_target)
    return

  if output:
    latest_backup_url = output.splitlines()[-1]
    archive_path = corpus_dir + '.zip'
    command = ['gsutil', '-q', 'cp', latest_backup_url, archive_path]
    subprocess.check_call(command)

    command = ['unzip', '-q', '-o', archive_path, '-d', corpus_dir]
    subprocess.check_call(command)
    os.remove(archive_path)
  else:
    # Sync the working corpus copy if a minimized backup is not available.
    corpus_url = CORPUS_URL_FORMAT.format(project_name=project.name,
                                          fuzz_target=fuzz_target)
    command = ['gsutil', '-m', '-q', 'rsync', '-R', corpus_url, corpus_dir]
    subprocess.check_call(command)


def download_corpora(args):
  """Downloads most recent corpora from GCS for the given project."""
  if not check_project_exists(args.project):
    return False

  try:
    with open(os.devnull, 'w') as stdout:
      subprocess.check_call(['gsutil', '--version'], stdout=stdout)
  except OSError:
    logging.error('gsutil not found. Please install it from '
                  'https://cloud.google.com/storage/docs/gsutil_install')
    return False

  if args.fuzz_target:
    fuzz_targets = [args.fuzz_target]
  else:
    fuzz_targets = _get_fuzz_targets(args.project)

  corpus_dir = args.project.corpus

  def _download_for_single_target(fuzz_target):
    try:
      _get_latest_corpus(args.project, fuzz_target, corpus_dir)
      return True
    except Exception as error:  # pylint:disable=broad-except
      logging.error('Corpus download for %s failed: %s.', fuzz_target,
                    str(error))
      return False

  logging.info('Downloading corpora for %s project to %s.', args.project.name,
               corpus_dir)
  thread_pool = ThreadPool()
  return all(thread_pool.map(_download_for_single_target, fuzz_targets))


def coverage(args):
  """Generates code coverage using clang source based code coverage."""
  if args.corpus_dir and not args.fuzz_target:
    logging.error(
        '--corpus-dir requires specifying a particular fuzz target using '
        '--fuzz-target')
    return False

  if not check_project_exists(args.project):
    return False

  if args.project.language not in constants.LANGUAGES_WITH_COVERAGE_SUPPORT:
    logging.error(
        'Project is written in %s, coverage for it is not supported yet.',
        args.project.language)
    return False

  if (not args.no_corpus_download and not args.corpus_dir and
      not args.project.is_external):
    if not download_corpora(args):
      return False

  env = [
      'FUZZING_ENGINE=libfuzzer',
      'FUZZING_LANGUAGE=%s' % args.project.language,
      'PROJECT=%s' % args.project.name,
      'SANITIZER=coverage',
      'HTTP_PORT=%s' % args.port,
      'COVERAGE_EXTRA_ARGS=%s' % ' '.join(args.extra_args),
  ]

  run_args = _env_to_docker_args(env)

  if args.port:
    run_args.extend([
        '-p',
        '%s:%s' % (args.port, args.port),
    ])

  if args.corpus_dir:
    if not os.path.exists(args.corpus_dir):
      logging.error('The path provided in --corpus-dir argument does not '
                    'exist.')
      return False
    corpus_dir = os.path.realpath(args.corpus_dir)
    run_args.extend(['-v', '%s:/corpus/%s' % (corpus_dir, args.fuzz_target)])
  else:
    run_args.extend(['-v', '%s:/corpus' % args.project.corpus])

  run_args.extend([
      '-v',
      '%s:/out' % args.project.out,
      '-t',
      BASE_RUNNER_IMAGE,
  ])

  run_args.append('coverage')
  if args.fuzz_target:
    run_args.append(args.fuzz_target)

  result = docker_run(run_args)
  if result:
    logging.info('Successfully generated clang code coverage report.')
  else:
    logging.error('Failed to generate clang code coverage report.')

  return result


def run_fuzzer(args):
  """Runs a fuzzer in the container."""
  if not check_project_exists(args.project):
    return False

  if not _check_fuzzer_exists(args.project, args.fuzzer_name):
    return False

  env = [
      'FUZZING_ENGINE=' + args.engine,
      'SANITIZER=' + args.sanitizer,
      'RUN_FUZZER_MODE=interactive',
  ]

  if args.e:
    env += args.e

  run_args = _env_to_docker_args(env)

  if args.corpus_dir:
    if not os.path.exists(args.corpus_dir):
      logging.error('The path provided in --corpus-dir argument does not exist')
      return False
    corpus_dir = os.path.realpath(args.corpus_dir)
    run_args.extend([
        '-v',
        '{corpus_dir}:/tmp/{fuzzer}_corpus'.format(corpus_dir=corpus_dir,
                                                   fuzzer=args.fuzzer_name)
    ])

  run_args.extend([
      '-v',
      '%s:/out' % args.project.out,
      '-t',
      BASE_RUNNER_IMAGE,
      'run_fuzzer',
      args.fuzzer_name,
  ] + args.fuzzer_args)

  return docker_run(run_args)


def reproduce(args):
  """Reproduces a specific test case from a specific project."""
  return reproduce_impl(args.project, args.fuzzer_name, args.valgrind, args.e,
                        args.fuzzer_args, args.testcase_path)


def reproduce_impl(  # pylint: disable=too-many-arguments
    project,
    fuzzer_name,
    valgrind,
    env_to_add,
    fuzzer_args,
    testcase_path,
    run_function=docker_run,
    err_result=False):
  """Reproduces a testcase in the container."""
  if not check_project_exists(project):
    return err_result

  if not _check_fuzzer_exists(project, fuzzer_name):
    return err_result

  debugger = ''
  env = []
  image_name = 'base-runner'

  if valgrind:
    debugger = 'valgrind --tool=memcheck --track-origins=yes --leak-check=full'

  if debugger:
    image_name = 'base-runner-debug'
    env += ['DEBUGGER=' + debugger]

  if env_to_add:
    env += env_to_add

  run_args = _env_to_docker_args(env) + [
      '-v',
      '%s:/out' % project.out,
      '-v',
      '%s:/testcase' % _get_absolute_path(testcase_path),
      '-t',
      'gcr.io/oss-fuzz-base/%s' % image_name,
      'reproduce',
      fuzzer_name,
      '-runs=100',
  ] + fuzzer_args

  return run_function(run_args)


def _validate_project_name(project_name):
  """Validates |project_name| is a valid OSS-Fuzz project name."""
  if len(project_name) > MAX_PROJECT_NAME_LENGTH:
    logging.error(
        'Project name needs to be less than or equal to %d characters.',
        MAX_PROJECT_NAME_LENGTH)
    return False

  if not VALID_PROJECT_NAME_REGEX.match(project_name):
    logging.info('Invalid project name: %s.', project_name)
    return False

  return True


def _validate_language(language):
  if not LANGUAGE_REGEX.match(language):
    logging.error('Invalid project language %s.', language)
    return False

  return True


def _create_build_integration_directory(directory):
  """Returns True on successful creation of a build integration directory.
  Suitable for OSS-Fuzz and external projects."""
  try:
    os.makedirs(directory)
  except OSError as error:
    if error.errno != errno.EEXIST:
      raise
    logging.error('%s already exists.', directory)
    return False
  return True


def _template_project_file(filename, template, template_args, directory):
  """Templates |template| using |template_args| and writes the result to
  |directory|/|filename|. Sets the file to executable if |filename| is
  build.sh."""
  file_path = os.path.join(directory, filename)
  with open(file_path, 'w') as file_handle:
    file_handle.write(template % template_args)

  if filename == 'build.sh':
    os.chmod(file_path, 0o755)


def generate(args):
  """Generates empty project files."""
  return _generate_impl(args.project, args.language)


def _get_current_datetime():
  """Returns this year. Needed for mocking."""
  return datetime.datetime.now()


def _base_builder_from_language(language):
  """Returns the base builder for the specified language."""
  if language not in LANGUAGES_WITH_BUILDER_IMAGES:
    return 'base-builder'
  return 'base-builder-{language}'.format(language=language)


def _generate_impl(project, language):
  """Implementation of generate(). Useful for testing."""
  if project.is_external:
    # External project.
    project_templates = templates.EXTERNAL_TEMPLATES
  else:
    # Internal project.
    if not _validate_project_name(project.name):
      return False
    project_templates = templates.TEMPLATES

  if not _validate_language(language):
    return False

  directory = project.build_integration_path
  if not _create_build_integration_directory(directory):
    return False

  logging.info('Writing new files to: %s.', directory)

  template_args = {
      'project_name': project.name,
      'base_builder': _base_builder_from_language(language),
      'language': language,
      'year': _get_current_datetime().year
  }
  for filename, template in project_templates.items():
    _template_project_file(filename, template, template_args, directory)
  return True


def shell(args):
  """Runs a shell within a docker image."""
  if not build_image_impl(args.project):
    return False

  env = [
      'FUZZING_ENGINE=' + args.engine,
      'SANITIZER=' + args.sanitizer,
      'ARCHITECTURE=' + args.architecture,
  ]

  if args.project.name != 'base-runner-debug':
    env.append('FUZZING_LANGUAGE=' + args.project.language)

  if args.e:
    env += args.e

  if is_base_image(args.project.name):
    image_project = 'oss-fuzz-base'
    out_dir = _get_out_dir()
  else:
    image_project = 'oss-fuzz'
    out_dir = args.project.out

  run_args = _env_to_docker_args(env)
  if args.source_path:
    run_args.extend([
        '-v',
        '%s:%s' % (_get_absolute_path(args.source_path), '/src'),
    ])

  run_args.extend([
      '-v',
      '%s:/out' % out_dir, '-v',
      '%s:/work' % args.project.work, '-t',
      'gcr.io/%s/%s' % (image_project, args.project.name), '/bin/bash'
  ])

  docker_run(run_args)
  return True


def pull_images(language=None):
  """Pulls base images used to build projects in language lang (or all if lang
  is None)."""
  for base_image_lang, base_images in BASE_IMAGES.items():
    if (language is None or base_image_lang == 'generic' or
        base_image_lang == language):
      for base_image in base_images:
        if not docker_pull(base_image):
          return False

  return True


if __name__ == '__main__':
  sys.exit(main())