# Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
# for details. All rights reserved. Use of this source code is governed by a
# BSD-style license that can be found in the LICENSE file.

# This file contains a set of utilities functions used by other Python-based
# scripts.

import commands
import contextlib
import datetime
import glob
import imp
import json
import os
import platform
import re
import shutil
import subprocess
import sys
import tarfile
import tempfile
import uuid

try:
  # Not available on Windows.
  import resource
except:
  pass

DART_DIR = os.path.abspath(
    os.path.normpath(os.path.join(__file__, '..', '..')))


def GetBotUtils():
  '''Dynamically load the tools/bots/bot_utils.py python module.'''
  return imp.load_source('bot_utils', os.path.join(DART_DIR, 'tools', 'bots', 'bot_utils.py'))


def GetMinidumpUtils():
  '''Dynamically load the tools/minidump.py python module.'''
  return imp.load_source('minidump', os.path.join(DART_DIR, 'tools', 'minidump.py'))


class Version(object):
  def __init__(self, channel, major, minor, patch, prerelease,
               prerelease_patch):
    self.channel = channel
    self.major = major
    self.minor = minor
    self.patch = patch
    self.prerelease = prerelease
    self.prerelease_patch = prerelease_patch


# Try to guess the host operating system.
def GuessOS():
  os_id = platform.system()
  if os_id == "Linux":
    return "linux"
  elif os_id == "Darwin":
    return "macos"
  elif os_id == "Windows" or os_id == "Microsoft":
    # On Windows Vista platform.system() can return "Microsoft" with some
    # versions of Python, see http://bugs.python.org/issue1082 for details.
    return "win32"
  elif os_id == 'FreeBSD':
    return 'freebsd'
  elif os_id == 'OpenBSD':
    return 'openbsd'
  elif os_id == 'SunOS':
    return 'solaris'
  else:
    return None


# Try to guess the host architecture.
def GuessArchitecture():
  os_id = platform.machine()
  if os_id.startswith('armv5te'):
    return 'armv5te'
  elif os_id.startswith('armv6'):
    return 'armv6'
  elif os_id.startswith('arm'):
    return 'arm'
  elif os_id.startswith('aarch64'):
    return 'arm64'
  elif '64' in os_id:
    return 'x64'
  elif (not os_id) or (not re.match('(x|i[3-6])86', os_id) is None):
    return 'ia32'
  elif os_id == 'i86pc':
    return 'ia32'
  else:
    guess_os = GuessOS()
    print "Warning: Guessing architecture %s based on os %s\n"\
          % (os_id, guess_os)
    if guess_os == 'win32':
      return 'ia32'
    return None


# Try to guess the number of cpus on this machine.
def GuessCpus():
  if os.getenv("DART_NUMBER_OF_CORES") is not None:
    return int(os.getenv("DART_NUMBER_OF_CORES"))
  if os.path.exists("/proc/cpuinfo"):
    return int(commands.getoutput("grep -E '^processor' /proc/cpuinfo | wc -l"))
  if os.path.exists("/usr/bin/hostinfo"):
    return int(commands.getoutput('/usr/bin/hostinfo |'
        ' grep "processors are logically available." |'
        ' awk "{ print \$1 }"'))
  win_cpu_count = os.getenv("NUMBER_OF_PROCESSORS")
  if win_cpu_count:
    return int(win_cpu_count)
  return 2


def GetWindowsRegistryKeyName(name):
  import win32process
  # Check if python process is 64-bit or if it's 32-bit running in 64-bit OS.
  # We need to know whether host is 64-bit so that we are looking in right
  # registry for Visual Studio path.
  if sys.maxsize > 2**32 or win32process.IsWow64Process():
    wow6432Node = 'Wow6432Node\\'
  else:
    wow6432Node = ''
  return r'SOFTWARE\%s%s' % (wow6432Node, name)


# Try to guess Visual Studio location when buiding on Windows.
def GuessVisualStudioPath():
  defaultPath = r"C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7" \
                r"\IDE"
  defaultExecutable = "devenv.com"

  if not IsWindows():
    return defaultPath, defaultExecutable

  keyNamesAndExecutables = [
    # Pair for non-Express editions.
    (GetWindowsRegistryKeyName(r'Microsoft\VisualStudio'), 'devenv.com'),
    # Pair for 2012 Express edition.
    (GetWindowsRegistryKeyName(r'Microsoft\VSWinExpress'), 'VSWinExpress.exe'),
    # Pair for pre-2012 Express editions.
    (GetWindowsRegistryKeyName(r'Microsoft\VCExpress'), 'VCExpress.exe')]

  bestGuess = (0.0, (defaultPath, defaultExecutable))

  import _winreg
  for (keyName, executable) in keyNamesAndExecutables:
    try:
      key = _winreg.OpenKey(_winreg.HKEY_LOCAL_MACHINE, keyName)
    except WindowsError:
      # Can't find this key - moving on the next one.
      continue

    try:
      subkeyCounter = 0
      while True:
        try:
          subkeyName = _winreg.EnumKey(key, subkeyCounter)
          subkeyCounter += 1
        except WindowsError:
          # Reached end of enumeration. Moving on the next key.
          break

        match = re.match(r'^\d+\.\d+$', subkeyName)
        if match:
          with _winreg.OpenKey(key, subkeyName) as subkey:
            try:
              (installDir, registrytype) = _winreg.QueryValueEx(subkey,
                                                                'InstallDir')
            except WindowsError:
              # Can't find value under the key - continue to the next key.
              continue
            isExpress = executable != 'devenv.com'
            if not isExpress and subkeyName == '14.0':
              # Stop search since if we found non-Express VS2015 version
              # installed, which is preferred version.
              return installDir, executable
            else:
              version = float(subkeyName)
              # We prefer higher version of Visual Studio and given equal
              # version numbers we prefer non-Express edition.
              if version > bestGuess[0]:
                bestGuess = (version, (installDir, executable))
    finally:
      _winreg.CloseKey(key)
  return bestGuess[1]


# Returns true if we're running under Windows.
def IsWindows():
  return GuessOS() == 'win32'


# Reads a text file into an array of strings - one for each
# line. Strips comments in the process.
def ReadLinesFrom(name):
  result = []
  for line in open(name):
    if '#' in line:
      line = line[:line.find('#')]
    line = line.strip()
    if len(line) == 0:
      continue
    result.append(line)
  return result


# Filters out all arguments until the next '--' argument
# occurs.
def ListArgCallback(option, value, parser):
   if value is None:
     value = []

   for arg in parser.rargs:
     if arg[:2].startswith('--'):
       break
     value.append(arg)

   del parser.rargs[:len(value)]
   setattr(parser.values, option.dest, value)


# Filters out all argument until the first non '-' or the
# '--' argument occurs.
def ListDartArgCallback(option, value, parser):
   if value is None:
     value = []

   for arg in parser.rargs:
     if arg[:2].startswith('--') or arg[0] != '-':
       break
     value.append(arg)

   del parser.rargs[:len(value)]
   setattr(parser.values, option.dest, value)


# Mapping table between build mode and build configuration.
BUILD_MODES = {
  'debug': 'Debug',
  'release': 'Release',
  'product': 'Product',
}


# Mapping table between OS and build output location.
BUILD_ROOT = {
  'win32': os.path.join('out'),
  'linux': os.path.join('out'),
  'freebsd': os.path.join('out'),
  'macos': os.path.join('xcodebuild'),
}

ARCH_FAMILY = {
  'ia32': 'ia32',
  'x64': 'ia32',
  'arm': 'arm',
  'armv6': 'arm',
  'armv5te': 'arm',
  'arm64': 'arm',
  'simarm': 'ia32',
  'simarmv6': 'ia32',
  'simarmv5te': 'ia32',
  'simarm64': 'ia32',
  'simdbc': 'ia32',
  'simdbc64': 'ia32',
  'armsimdbc': 'arm',
  'armsimdbc64': 'arm',
}

ARCH_GUESS = GuessArchitecture()
BASE_DIR = os.path.abspath(os.path.join(os.curdir, '..'))
DART_DIR = os.path.abspath(os.path.join(__file__, '..', '..'))
VERSION_FILE = os.path.join(DART_DIR, 'tools', 'VERSION')


def GetBuildbotGSUtilPath():
  gsutil = '/b/build/scripts/slave/gsutil'
  if platform.system() == 'Windows':
    gsutil = 'e:\\\\b\\build\\scripts\\slave\\gsutil'
  return gsutil


def GetBuildMode(mode):
  return BUILD_MODES[mode]


def GetArchFamily(arch):
  return ARCH_FAMILY[arch]


def IsCrossBuild(target_os, arch):
  host_arch = ARCH_GUESS
  return ((GetArchFamily(host_arch) != GetArchFamily(arch)) or
          (target_os != GuessOS()))


def GetBuildConf(mode, arch, conf_os=None):
  if conf_os == 'android':
    return '%s%s%s' % (GetBuildMode(mode), conf_os.title(), arch.upper())
  else:
    # Ask for a cross build if the host and target architectures don't match.
    host_arch = ARCH_GUESS
    cross_build = ''
    if GetArchFamily(host_arch) != GetArchFamily(arch):
      cross_build = 'X'
    return '%s%s%s' % (GetBuildMode(mode), cross_build, arch.upper())


def GetBuildDir(host_os):
  return BUILD_ROOT[host_os]


def GetBuildRoot(host_os, mode=None, arch=None, target_os=None):
  build_root = GetBuildDir(host_os)
  if mode:
    build_root = os.path.join(build_root,
                              GetBuildConf(mode, arch, target_os))
  return build_root


def GetBuildSdkBin(host_os, mode=None, arch=None, target_os=None):
  build_root = GetBuildRoot(host_os, mode, arch, target_os)
  return os.path.join(build_root, 'dart-sdk', 'bin')


def GetBaseDir():
  return BASE_DIR


def GetShortVersion():
  version = ReadVersionFile()
  return ('%s.%s.%s.%s.%s' % (
      version.major, version.minor, version.patch, version.prerelease,
      version.prerelease_patch))


def GetSemanticSDKVersion(no_git_hash=False):
  version = ReadVersionFile()
  if not version:
    return None

  if version.channel == 'be':
    postfix = '-edge' if no_git_hash else '-edge.%s' % GetGitRevision()
  elif version.channel == 'dev':
    postfix = '-dev.%s.%s' % (version.prerelease, version.prerelease_patch)
  else:
    assert version.channel == 'stable'
    postfix = ''

  return '%s.%s.%s%s' % (version.major, version.minor, version.patch, postfix)


def GetVersion(no_git_hash=False):
  return GetSemanticSDKVersion(no_git_hash)


# The editor used to produce the VERSION file put on gcs. We now produce this
# in the bots archiving the sdk.
# The content looks like this:
#{
#  "date": "2015-05-28",
#  "version": "1.11.0-edge.131653",
#  "revision": "535394c2657ede445142d8a92486d3899bbf49b5"
#}
def GetVersionFileContent():
  result = {"date": str(datetime.date.today()),
            "version": GetVersion(),
            "revision": GetGitRevision()}
  return json.dumps(result, indent=2)


def GetChannel():
  version = ReadVersionFile()
  return version.channel


def GetUserName():
  key = 'USER'
  if sys.platform == 'win32':
    key = 'USERNAME'
  return os.environ.get(key, '')


def ReadVersionFile():
  def match_against(pattern, file_content):
    match = re.search(pattern, file_content, flags=re.MULTILINE)
    if match:
      return match.group(1)
    return None

  try:
    fd = open(VERSION_FILE)
    content = fd.read()
    fd.close()
  except:
    print "Warning: Couldn't read VERSION file (%s)" % VERSION_FILE
    return None

  channel = match_against('^CHANNEL ([A-Za-z0-9]+)$', content)
  major = match_against('^MAJOR (\d+)$', content)
  minor = match_against('^MINOR (\d+)$', content)
  patch = match_against('^PATCH (\d+)$', content)
  prerelease = match_against('^PRERELEASE (\d+)$', content)
  prerelease_patch = match_against('^PRERELEASE_PATCH (\d+)$', content)

  if channel and major and minor and prerelease and prerelease_patch:
    return Version(
        channel, major, minor, patch, prerelease, prerelease_patch)
  else:
    print "Warning: VERSION file (%s) has wrong format" % VERSION_FILE
    return None


# Our schema for releases and archiving is based on an increasing
# sequence of numbers. In the svn world this was simply the revision of a
# commit, which would always give us a one to one mapping between the number
# and the commit. This was true across branches as well, so a number used
# to archive a build was always unique and unambiguous.
# In git there is no such global number, so we loosen the requirement a bit.
# We only use numbers on the master branch (bleeding edge). On branches
# we use the version number instead for archiving purposes.
# The number on master is the count of commits on the master branch.
def GetArchiveVersion():
  version = ReadVersionFile()
  if not version:
    raise 'Could not get the archive version, parsing the version file failed'
  if version.channel in ['be', 'integration']:
    return GetGitNumber()
  return GetSemanticSDKVersion()


def GetGitRevision():
  # When building from tarball use tools/GIT_REVISION
  git_revision_file = os.path.join(DART_DIR, 'tools', 'GIT_REVISION')
  try:
    with open(git_revision_file) as fd:
      return fd.read()
  except:
    pass

  p = subprocess.Popen(['git', 'log', '-n', '1', '--pretty=format:%H'],
                       stdout = subprocess.PIPE,
                       stderr = subprocess.STDOUT, shell=IsWindows(),
                       cwd = DART_DIR)
  output, _ = p.communicate()
  # We expect a full git hash
  if len(output) != 40:
    print "Warning: could not parse git commit, output was %s" % output
    return None
  return output


def GetShortGitHash():
  p = subprocess.Popen(['git', 'log', '-n', '1', '--pretty=format:%h'],
                       stdout = subprocess.PIPE,
                       stderr = subprocess.STDOUT, shell=IsWindows(),
                       cwd = DART_DIR)
  output, _ = p.communicate()
  if p.wait() != 0:
    return None
  return output


def GetLatestDevTag():
  cmd = [
    'git',
    'for-each-ref',
    'refs/tags/*dev*',
    '--sort=-taggerdate',
    "--format=%(refname:lstrip=2)",
    '--count=1',
  ]
  p = subprocess.Popen(cmd,
                       stdout = subprocess.PIPE,
                       stderr = subprocess.STDOUT, shell=IsWindows(),
                       cwd = DART_DIR)
  output, _ = p.communicate()
  if p.wait() != 0:
    print "Warning: Could not get the most recent dev branch tag %s" % output
    return None
  return output.strip()


def GetGitTimestamp():
  p = subprocess.Popen(['git', 'log', '-n', '1', '--pretty=format:%cd'],
                       stdout = subprocess.PIPE,
                       stderr = subprocess.STDOUT, shell=IsWindows(),
                       cwd = DART_DIR)
  output, _ = p.communicate()
  if p.wait() != 0:
    return None
  return output


# To eliminate clashing with older archived builds on bleeding edge we add
# a base number bigger the largest svn revision (this also gives us an easy
# way of seeing if an archive comes from git based or svn based commits).
GIT_NUMBER_BASE = 100000
def GetGitNumber():
  p = subprocess.Popen(['git', 'rev-list', 'HEAD', '--count'],
                       stdout = subprocess.PIPE,
                       stderr = subprocess.STDOUT, shell=IsWindows(),
                       cwd = DART_DIR)
  output, _ = p.communicate()
  try:
    number = int(output)
    return number + GIT_NUMBER_BASE
  except:
    print "Warning: could not parse git count, output was %s" % output
  return None


def ParseGitInfoOutput(output):
  """Given a git log, determine the latest corresponding svn revision."""
  for line in output.split('\n'):
    tokens = line.split()
    if len(tokens) > 0 and tokens[0] == 'git-svn-id:':
      return tokens[1].split('@')[1]
  return None


def ParseSvnInfoOutput(output):
  revision_match = re.search('Last Changed Rev: (\d+)', output)
  if revision_match:
    return revision_match.group(1)
  return None


def RewritePathSeparator(path, workspace):
  # Paths in test files are always specified using '/'
  # as the path separator. Replace with the actual
  # path separator before use.
  if '/' in path:
    split_path = path.split('/')
    path = os.sep.join(split_path)
    path = os.path.join(workspace, path)
    if not os.path.exists(path):
      raise Exception(path)
  return path


def ParseTestOptions(pattern, source, workspace):
  match = pattern.search(source)
  if match:
    return [RewritePathSeparator(o, workspace) for o in match.group(1).split(' ')]
  else:
    return None


def ParseTestOptionsMultiple(pattern, source, workspace):
  matches = pattern.findall(source)
  if matches:
    result = []
    for match in matches:
      if len(match) > 0:
        result.append(
            [RewritePathSeparator(o, workspace) for o in match.split(' ')])
      else:
        result.append([])
    return result
  else:
    return None


def Daemonize():
  """
  Create a detached background process (daemon). Returns True for
  the daemon, False for the parent process.
  See: http://www.faqs.org/faqs/unix-faq/programmer/faq/
  "1.7 How do I get my program to act like a daemon?"
  """
  if os.fork() > 0:
    return False
  os.setsid()
  if os.fork() > 0:
    exit(0)
    raise
  return True


def PrintError(string):
  """Writes and flushes a string to stderr."""
  sys.stderr.write(string)
  sys.stderr.write('\n')


def CheckedUnlink(name):
  """Unlink a file without throwing an exception."""
  try:
    os.unlink(name)
  except OSError, e:
    PrintError("os.unlink() " + str(e))


def Main():
  print "GuessOS() -> ", GuessOS()
  print "GuessArchitecture() -> ", GuessArchitecture()
  print "GuessCpus() -> ", GuessCpus()
  print "IsWindows() -> ", IsWindows()
  print "GuessVisualStudioPath() -> ", GuessVisualStudioPath()
  print "GetGitRevision() -> ", GetGitRevision()
  print "GetGitTimestamp() -> ", GetGitTimestamp()
  print "GetVersionFileContent() -> ", GetVersionFileContent()
  print "GetGitNumber() -> ", GetGitNumber()


class Error(Exception):
  pass


class ToolError(Exception):
  """Deprecated exception, use Error instead."""

  def __init__(self, value):
    self.value = value

  def __str__(self):
    return repr(self.value)


def IsCrashExitCode(exit_code):
  if IsWindows():
    return 0x80000000 & exit_code
  else:
    return exit_code < 0


def DiagnoseExitCode(exit_code, command):
  if IsCrashExitCode(exit_code):
    sys.stderr.write('Command: %s\nCRASHED with exit code %d (0x%x)\n' % (
        ' '.join(command), exit_code, exit_code & 0xffffffff))


def Touch(name):
  with file(name, 'a'):
    os.utime(name, None)


def ExecuteCommand(cmd):
  """Execute a command in a subprocess."""
  print 'Executing: ' + ' '.join(cmd)
  pipe = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.PIPE,
      shell=IsWindows())
  output = pipe.communicate()
  if pipe.returncode != 0:
    raise Exception('Execution failed: ' + str(output))
  return pipe.returncode, output


# The checked-in SDKs are documented at
#     https://github.com/dart-lang/sdk/wiki/The-checked-in-SDK-in-tools
def CheckedInSdkPath():
  # We don't use the normal macos, linux, win32 directory names here, instead,
  # we use the names that the download_from_google_storage script uses.
  osdict = {'Darwin':'mac', 'Linux':'linux', 'Windows':'win'}
  system = platform.system()
  try:
    osname = osdict[system]
  except KeyError:
    print >>sys.stderr, ('WARNING: platform "%s" not supported') % (system)
    return None
  tools_dir = os.path.dirname(os.path.realpath(__file__))
  return os.path.join(tools_dir,
                      'sdks',
                      'dart-sdk')


def CheckedInSdkExecutable():
  name = 'dart'
  if IsWindows():
    name = 'dart.exe'
  return os.path.join(CheckedInSdkPath(), 'bin', name)

def CheckedInSdkCheckExecutable():
  executable = CheckedInSdkExecutable()
  canary_script = os.path.join(os.path.dirname(os.path.realpath(__file__)),
                               'canary.dart')
  try:
    with open(os.devnull, 'wb') as silent_sink:
      if 0 == subprocess.call([executable, canary_script], stdout=silent_sink):
        return True
  except OSError as e:
    pass
  return False


def CheckLinuxCoreDumpPattern(fatal=False):
  core_pattern_file = '/proc/sys/kernel/core_pattern'
  core_pattern = open(core_pattern_file).read()

  expected_core_pattern = 'core.%p'
  if core_pattern.strip() != expected_core_pattern:
    message = ('Invalid core_pattern configuration. '
        'The configuration of core dump handling is *not* correct for '
        'a buildbot. The content of {0} must be "{1}" instead of "{2}".'
        .format(core_pattern_file, expected_core_pattern, core_pattern))
    if fatal:
      raise Exception(message)
    else:
      print message
      return False
  return True


class TempDir(object):
  def __init__(self, prefix=''):
    self._temp_dir = None
    self._prefix = prefix

  def __enter__(self):
    self._temp_dir = tempfile.mkdtemp(self._prefix)
    return self._temp_dir

  def __exit__(self, *_):
    shutil.rmtree(self._temp_dir, ignore_errors=True)


class ChangedWorkingDirectory(object):
  def __init__(self, working_directory):
    self._working_directory = working_directory

  def __enter__(self):
    self._old_cwd = os.getcwd()
    print "Enter directory = ", self._working_directory
    os.chdir(self._working_directory)

  def __exit__(self, *_):
    print "Enter directory = ", self._old_cwd
    os.chdir(self._old_cwd)


class UnexpectedCrash(object):
  def __init__(self, test, pid, binary):
    self.test = test
    self.pid = pid
    self.binary = binary

  def __str__(self):
    return "Crash(%s: %s %s)" % (self.test, self.binary, self.pid)


class PosixCoreDumpEnabler(object):
  def __init__(self):
    self._old_limits = None

  def __enter__(self):
    self._old_limits = resource.getrlimit(resource.RLIMIT_CORE)
    resource.setrlimit(resource.RLIMIT_CORE, (-1, -1))

  def __exit__(self, *_):
    resource.setrlimit(resource.RLIMIT_CORE, self._old_limits)


class LinuxCoreDumpEnabler(PosixCoreDumpEnabler):
  def __enter__(self):
    # Bump core limits to unlimited if core_pattern is correctly configured.
    if CheckLinuxCoreDumpPattern(fatal=False):
      super(LinuxCoreDumpEnabler, self).__enter__()

  def __exit__(self, *args):
    CheckLinuxCoreDumpPattern(fatal=False)
    super(LinuxCoreDumpEnabler, self).__exit__(*args)


class WindowsCoreDumpEnabler(object):
  """This enabler assumes that Dart binary was built with Crashpad support.
  In this case DART_CRASHPAD_CRASHES_DIR environment variable allows to
  specify the location of Crashpad crashes database. Actual minidumps will
  be written into reports subfolder of the database.
  """
  CRASHPAD_DB_FOLDER = os.path.join(DART_DIR, r'crashes')
  DUMPS_FOLDER = os.path.join(CRASHPAD_DB_FOLDER, r'reports')

  def __init__(self):
    pass

  def __enter__(self):
    print "INFO: Enabling coredump archiving into %s" % (WindowsCoreDumpEnabler.CRASHPAD_DB_FOLDER)
    os.environ['DART_CRASHPAD_CRASHES_DIR'] = WindowsCoreDumpEnabler.CRASHPAD_DB_FOLDER

  def __exit__(self, *_):
    del os.environ['DART_CRASHPAD_CRASHES_DIR']


def TryUnlink(file):
  try:
    os.unlink(file)
  except Exception as error:
    print "ERROR: Failed to remove %s: %s" % (file, error)


class BaseCoreDumpArchiver(object):
  """This class reads coredumps file written by UnexpectedCrashDumpArchiver
  into the current working directory and uploads all cores and binaries
  listed in it into Cloud Storage (see tools/testing/dart/test_progress.dart).
  """

  # test.dart will write a line for each unexpected crash into this file.
  _UNEXPECTED_CRASHES_FILE = "unexpected-crashes"

  def __init__(self, search_dir, output_directory):
    self._bucket = 'dart-temp-crash-archive'
    self._binaries_dir = os.getcwd()
    self._search_dir = search_dir
    self._output_directory = output_directory

  def _safe_cleanup(self):
    try:
      return self._cleanup();
    except Exception as error:
      print "ERROR: Failure during cleanup: %s" % error
      return False

  def __enter__(self):
    print "INFO: Core dump archiving is activated"

    # Cleanup any stale files
    if self._safe_cleanup():
      print "WARNING: Found and removed stale coredumps"

  def __exit__(self, *_):
    try:
      crashes = self._find_unexpected_crashes()
      if crashes:
        # If we get a ton of crashes, only archive 10 dumps.
        archive_crashes = crashes[:10]
        print 'Archiving coredumps for crash (if possible):'
        for crash in archive_crashes:
          print '----> %s' % crash

        sys.stdout.flush()

        self._archive(archive_crashes)
      else:
        print "INFO: No unexpected crashes recorded"
        dumps = self._find_all_coredumps()
        if dumps:
          print "INFO: However there are %d core dumps found" % len(dumps)
          for dump in dumps:
            print "INFO:        -> %s" % dump
          print
    except Exception as error:
      print "ERROR: Failed to archive crashes: %s" % error
      raise

    finally:
      self._safe_cleanup()

  def _archive(self, crashes):
    files = set()
    missing = []
    for crash in crashes:
      files.add(crash.binary)
      core = self._find_coredump_file(crash)
      if core:
        files.add(core)
      else:
        missing.append(crash)
    if self._output_directory is not None and self._is_shard():
      print (
          "INFO: Copying collected dumps and binaries into output directory\n"
          "INFO: They will be uploaded to isolate server. Look for \"isolated"
          " out\" under the failed step on the build page.\n"
          "INFO: For more information see runtime/docs/infra/coredumps.md")
      self._copy(files)
    else:
      print (
          "INFO: Uploading collected dumps and binaries into Cloud Storage\n"
          "INFO: Use `gsutil.py cp from-url to-path` to download them.\n"
          "INFO: For more information see runtime/docs/infra/coredumps.md")
      self._upload(files)

    if missing:
      self._report_missing_crashes(missing, throw=True)

  # todo(athom): move the logic to decide where to copy core dumps into the recipes.
  def _is_shard(self):
    return 'BUILDBOT_BUILDERNAME' not in os.environ

  def _report_missing_crashes(self, missing, throw=True):
    missing_as_string = ', '.join([str(c) for c in missing])
    other_files = list(glob.glob(os.path.join(self._search_dir, '*')))
    print >> sys.stderr, (
        "Could not find crash dumps for '%s' in search directory '%s'.\n"
        "Existing files which *did not* match the pattern inside the search "
        "directory are are:\n  %s"
        % (missing_as_string, self._search_dir, '\n  '.join(other_files)))
    if throw:
      raise Exception('Missing crash dumps for: %s' % missing_as_string)

  def _copy(self, files):
    for file in files:
      tarname = self._tar(file)
      print '+++ Copying %s to output_directory (%s)' % (tarname, self._output_directory)
      shutil.copy(tarname, self._output_directory)

  def _tar(self, file):
    # Sanitize the name: actual cores follow 'core.%d' pattern, crashed
    # binaries are copied next to cores and named
    # 'binary.<mode>_<arch>_<binary_name>'.
    # This should match the code in testing/dart/test_progress.dart
    name = os.path.basename(file)
    (prefix, suffix) = name.split('.', 1)
    is_binary = prefix == 'binary'
    if is_binary:
      (mode, arch, binary_name) = suffix.split('_', 2)
      name = binary_name

    tarname = '%s.tar.gz' % name

    # Compress the file.
    tar = tarfile.open(tarname, mode='w:gz')
    tar.add(file, arcname=name)
    if is_binary and os.path.exists(file + '.pdb'):
      # Also add a PDB file if there is one.
      tar.add(file + '.pdb', arcname=name + '.pdb')
    tar.close()
    return tarname

  def _upload(self, files):
    bot_utils = GetBotUtils()
    gsutil = bot_utils.GSUtil()
    storage_path = '%s/%s/' % (self._bucket, uuid.uuid4())
    gs_prefix = 'gs://%s' % storage_path
    http_prefix = 'https://storage.cloud.google.com/%s' % storage_path

    print '\n--- Uploading into %s (%s) ---' % (gs_prefix, http_prefix)
    for file in files:
      tarname = self._tar(file)

      # Remove / from absolute path to not have // in gs path.
      gs_url = '%s%s' % (gs_prefix, tarname)
      http_url = '%s%s' % (http_prefix, tarname)

      try:
        gsutil.upload(tarname, gs_url)
        print '+++ Uploaded %s (%s)' % (gs_url, http_url)
      except Exception as error:
        print '!!! Failed to upload %s, error: %s' % (tarname, error)

      TryUnlink(tarname)

    print '--- Done ---\n'

  def _find_all_coredumps(self):
    """Return coredumps that were recorded (if supported by the platform).
    This method will be overriden by concrete platform specific implementations.
    """
    return []

  def _find_unexpected_crashes(self):
    """Load coredumps file. Each line has the following format:

        test-name,pid,binary-file
    """
    try:
      with open(BaseCoreDumpArchiver._UNEXPECTED_CRASHES_FILE) as f:
        return [UnexpectedCrash(*ln.strip('\n').split(',')) for ln in f.readlines()]
    except:
      return []

  def _cleanup(self):
    found = False
    if os.path.exists(BaseCoreDumpArchiver._UNEXPECTED_CRASHES_FILE):
      os.unlink(BaseCoreDumpArchiver._UNEXPECTED_CRASHES_FILE)
      found = True
    for binary in glob.glob(os.path.join(self._binaries_dir, 'binary.*')):
      found = True
      TryUnlink(binary)

    return found

class PosixCoreDumpArchiver(BaseCoreDumpArchiver):
  def __init__(self, search_dir, output_directory):
    super(PosixCoreDumpArchiver, self).__init__(search_dir, output_directory)

  def _cleanup(self):
    found = super(PosixCoreDumpArchiver, self)._cleanup()
    for core in glob.glob(os.path.join(self._search_dir, 'core.*')):
      found = True
      TryUnlink(core)
    return found

  def _find_coredump_file(self, crash):
    core_filename = os.path.join(self._search_dir, 'core.%s' % crash.pid)
    if os.path.exists(core_filename):
      return core_filename


class LinuxCoreDumpArchiver(PosixCoreDumpArchiver):
  def __init__(self, output_directory):
    super(LinuxCoreDumpArchiver, self).__init__(os.getcwd(), output_directory)


class MacOSCoreDumpArchiver(PosixCoreDumpArchiver):
  def __init__(self, output_directory):
    super(MacOSCoreDumpArchiver, self).__init__('/cores', output_directory)


class WindowsCoreDumpArchiver(BaseCoreDumpArchiver):
  def __init__(self, output_directory):
    super(WindowsCoreDumpArchiver, self).__init__(
        WindowsCoreDumpEnabler.DUMPS_FOLDER, output_directory)
    self._dumps_by_pid = None

  # Find CDB.exe in the win_toolchain that we are using.
  def _find_cdb(self):
    win_toolchain_json_path = os.path.join(
        DART_DIR, 'build', 'win_toolchain.json')
    if not os.path.exists(win_toolchain_json_path):
      return None

    with open(win_toolchain_json_path, "r") as f:
      win_toolchain_info = json.loads(f.read())

    win_sdk_path = win_toolchain_info['win_sdk']

    # We assume that we are running on 64-bit Windows.
    # Note: x64 CDB can work with both X64 and IA32 dumps.
    cdb_path = os.path.join(win_sdk_path, 'Debuggers', 'x64', 'cdb.exe')
    if not os.path.exists(cdb_path):
      return None

    return cdb_path

  CDBG_PROMPT_RE = re.compile(r'^\d+:\d+>')

  def _dump_all_stacks(self):
    # On Windows due to crashpad integration crashes do not produce any
    # stacktraces. Dump stack traces from dumps Crashpad collected using
    # CDB (if available).
    cdb_path = self._find_cdb()
    if cdb_path is None:
      return

    dumps = self._find_all_coredumps()
    if not dumps:
      return

    print "### Collected %d crash dumps" % len(dumps)
    for dump in dumps:
      print
      print "### Dumping stacks from %s using CDB" % dump
      cdb_output = subprocess.check_output(
          '"%s" -z "%s" -kqm -c "!uniqstack -b -v -p;qd"' % (cdb_path, dump),
          stderr=subprocess.STDOUT)
      # Extract output of uniqstack from the whole output of CDB.
      output = False
      for line in cdb_output.split('\n'):
        if re.match(WindowsCoreDumpArchiver.CDBG_PROMPT_RE, line):
          output = True
        elif line.startswith("quit:"):
          break
        elif output:
          print line
    print
    print "#############################################"
    print


  def __exit__(self, *args):
    try:
      self._dump_all_stacks()
    except Exception as error:
      print "ERROR: Unable to dump stacks from dumps: %s" % error

    super(WindowsCoreDumpArchiver, self).__exit__(*args)


  def _cleanup(self):
    found = super(WindowsCoreDumpArchiver, self)._cleanup()
    for core in glob.glob(os.path.join(self._search_dir, '*')):
      found = True
      TryUnlink(core)
    return found

  def _find_all_coredumps(self):
    pattern = os.path.join(self._search_dir, '*.dmp')
    return [core_filename for core_filename in glob.glob(pattern)]

  def _find_coredump_file(self, crash):
    if self._dumps_by_pid is None:
      # If this function is invoked the first time then look through the directory
      # that contains crashes for all dump files and collect pid -> filename
      # mapping.
      self._dumps_by_pid = {}
      minidump = GetMinidumpUtils()
      pattern = os.path.join(self._search_dir, '*.dmp')
      for core_filename in glob.glob(pattern):
        pid = minidump.GetProcessIdFromDump(core_filename)
        if pid != -1:
          self._dumps_by_pid[str(pid)] = core_filename
    if crash.pid in self._dumps_by_pid:
      return self._dumps_by_pid[crash.pid]

  def _report_missing_crashes(self, missing, throw=True):
    # Let's only print the debugging information and not throw. We'll do more
    # validation for werfault.exe and throw afterwards.
    super(WindowsCoreDumpArchiver, self)._report_missing_crashes(missing, throw=False)

    if throw:
      missing_as_string = ', '.join([str(c) for c in missing])
      raise Exception('Missing crash dumps for: %s' % missing_as_string)

class IncreasedNumberOfFileDescriptors(object):
  def __init__(self, nofiles):
    self._old_limits = None
    self._limits = (nofiles, nofiles)

  def __enter__(self):
    self._old_limits = resource.getrlimit(resource.RLIMIT_NOFILE)
    resource.setrlimit(resource.RLIMIT_NOFILE, self._limits)

  def __exit__(self, *_):
    resource.setrlimit(resource.RLIMIT_CORE, self._old_limits)

@contextlib.contextmanager
def NooptContextManager():
  yield


def CoreDumpArchiver(args):
  enabled = '--copy-coredumps' in args
  prefix = '--output_directory='
  output_directory = next((arg[len(prefix):] for arg in args if arg.startswith(prefix)), None)

  if not enabled:
    return NooptContextManager()

  osname = GuessOS()
  if osname == 'linux':
    return contextlib.nested(LinuxCoreDumpEnabler(),
                             LinuxCoreDumpArchiver(output_directory))
  elif osname == 'macos':
    return contextlib.nested(PosixCoreDumpEnabler(),
                             MacOSCoreDumpArchiver(output_directory))
  elif osname == 'win32':
    return contextlib.nested(WindowsCoreDumpEnabler(),
                             WindowsCoreDumpArchiver(output_directory))
  else:
    # We don't have support for MacOS yet.
    return NooptContextManager()

def FileDescriptorLimitIncreaser():
  osname = GuessOS()
  if osname == 'macos':
    return IncreasedNumberOfFileDescriptors(nofiles=10000)
  else:
    assert osname in ('linux', 'win32')
    # We don't have support for MacOS yet.
    return NooptContextManager()

if __name__ == "__main__":
  import sys
  Main()