Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 575 insertions, 0 deletions

diff --git a/third_party/libwebrtc/build/vs_toolchain.py b/third_party/libwebrtc/build/vs_toolchain.py
new file mode 100755
index 0000000000..55372ba3a8
--- /dev/null
+++ b/third_party/libwebrtc/build/vs_toolchain.py
@@ -0,0 +1,575 @@
+#!/usr/bin/env python
+# Copyright 2014 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.
+
+from __future__ import print_function
+
+import collections
+import glob
+import json
+import os
+import pipes
+import platform
+import re
+import shutil
+import stat
+import subprocess
+import sys
+
+from gn_helpers import ToGNString
+
+# VS 2019 16.61 with 10.0.19041 SDK, and 10.0.20348 version of
+# d3dcompiler_47.dll, with ARM64 libraries and UWP support.
+# See go/chromium-msvc-toolchain for instructions about how to update the
+# toolchain.
+#
+# When updating the toolchain, consider the following areas impacted by the
+# toolchain version:
+#
+# * //base/win/windows_version.cc NTDDI preprocessor check
+#   Triggers a compiler error if the available SDK is older than the minimum.
+# * //build/config/win/BUILD.gn NTDDI_VERSION value
+#   Affects the availability of APIs in the toolchain headers.
+# * //docs/windows_build_instructions.md mentions of VS or Windows SDK.
+#   Keeps the document consistent with the toolchain version.
+TOOLCHAIN_HASH = '3bda71a11e'
+
+script_dir = os.path.dirname(os.path.realpath(__file__))
+json_data_file = os.path.join(script_dir, 'win_toolchain.json')
+
+# VS versions are listed in descending order of priority (highest first).
+MSVS_VERSIONS = collections.OrderedDict([
+  ('2019', '16.0'),
+  ('2017', '15.0'),
+])
+
+# List of preferred VC toolset version based on MSVS
+MSVC_TOOLSET_VERSION = {
+   '2019' : 'VC142',
+   '2017' : 'VC141',
+}
+
+def _HostIsWindows():
+  """Returns True if running on a Windows host (including under cygwin)."""
+  return sys.platform in ('win32', 'cygwin')
+
+def SetEnvironmentAndGetRuntimeDllDirs():
+  """Sets up os.environ to use the depot_tools VS toolchain with gyp, and
+  returns the location of the VC runtime DLLs so they can be copied into
+  the output directory after gyp generation.
+
+  Return value is [x64path, x86path, 'Arm64Unused'] or None. arm64path is
+  generated separately because there are multiple folders for the arm64 VC
+  runtime.
+  """
+  vs_runtime_dll_dirs = None
+  depot_tools_win_toolchain = \
+      bool(int(os.environ.get('DEPOT_TOOLS_WIN_TOOLCHAIN', '1')))
+  # When running on a non-Windows host, only do this if the SDK has explicitly
+  # been downloaded before (in which case json_data_file will exist).
+  if ((_HostIsWindows() or os.path.exists(json_data_file))
+      and depot_tools_win_toolchain):
+    if ShouldUpdateToolchain():
+      if len(sys.argv) > 1 and sys.argv[1] == 'update':
+        update_result = Update()
+      else:
+        update_result = Update(no_download=True)
+      if update_result != 0:
+        raise Exception('Failed to update, error code %d.' % update_result)
+    with open(json_data_file, 'r') as tempf:
+      toolchain_data = json.load(tempf)
+
+    toolchain = toolchain_data['path']
+    version = toolchain_data['version']
+    win_sdk = toolchain_data.get('win_sdk')
+    wdk = toolchain_data['wdk']
+    # TODO(scottmg): The order unfortunately matters in these. They should be
+    # split into separate keys for x64/x86/arm64. (See CopyDlls call below).
+    # http://crbug.com/345992
+    vs_runtime_dll_dirs = toolchain_data['runtime_dirs']
+    # The number of runtime_dirs in the toolchain_data was two (x64/x86) but
+    # changed to three (x64/x86/arm64) and this code needs to handle both
+    # possibilities, which can change independently from this code.
+    if len(vs_runtime_dll_dirs) == 2:
+      vs_runtime_dll_dirs.append('Arm64Unused')
+
+    os.environ['GYP_MSVS_OVERRIDE_PATH'] = toolchain
+
+    os.environ['WINDOWSSDKDIR'] = win_sdk
+    os.environ['WDK_DIR'] = wdk
+    # Include the VS runtime in the PATH in case it's not machine-installed.
+    runtime_path = os.path.pathsep.join(vs_runtime_dll_dirs)
+    os.environ['PATH'] = runtime_path + os.path.pathsep + os.environ['PATH']
+  elif sys.platform == 'win32' and not depot_tools_win_toolchain:
+    if not 'GYP_MSVS_OVERRIDE_PATH' in os.environ:
+      os.environ['GYP_MSVS_OVERRIDE_PATH'] = DetectVisualStudioPath()
+
+    # When using an installed toolchain these files aren't needed in the output
+    # directory in order to run binaries locally, but they are needed in order
+    # to create isolates or the mini_installer. Copying them to the output
+    # directory ensures that they are available when needed.
+    bitness = platform.architecture()[0]
+    # When running 64-bit python the x64 DLLs will be in System32
+    # ARM64 binaries will not be available in the system directories because we
+    # don't build on ARM64 machines.
+    x64_path = 'System32' if bitness == '64bit' else 'Sysnative'
+    x64_path = os.path.join(os.path.expandvars('%windir%'), x64_path)
+    vs_runtime_dll_dirs = [x64_path,
+                           os.path.join(os.path.expandvars('%windir%'),
+                                        'SysWOW64'),
+                           'Arm64Unused']
+
+  return vs_runtime_dll_dirs
+
+
+def _RegistryGetValueUsingWinReg(key, value):
+  """Use the _winreg module to obtain the value of a registry key.
+
+  Args:
+    key: The registry key.
+    value: The particular registry value to read.
+  Return:
+    contents of the registry key's value, or None on failure.  Throws
+    ImportError if _winreg is unavailable.
+  """
+  import _winreg
+  try:
+    root, subkey = key.split('\\', 1)
+    assert root == 'HKLM'  # Only need HKLM for now.
+    with _winreg.OpenKey(_winreg.HKEY_LOCAL_MACHINE, subkey) as hkey:
+      return _winreg.QueryValueEx(hkey, value)[0]
+  except WindowsError:
+    return None
+
+
+def _RegistryGetValue(key, value):
+  try:
+    return _RegistryGetValueUsingWinReg(key, value)
+  except ImportError:
+    raise Exception('The python library _winreg not found.')
+
+
+def GetVisualStudioVersion():
+  """Return best available version of Visual Studio.
+  """
+  supported_versions = list(MSVS_VERSIONS.keys())
+
+  # VS installed in depot_tools for Googlers
+  if bool(int(os.environ.get('DEPOT_TOOLS_WIN_TOOLCHAIN', '1'))):
+    return supported_versions[0]
+
+  # VS installed in system for external developers
+  supported_versions_str = ', '.join('{} ({})'.format(v,k)
+      for k,v in MSVS_VERSIONS.items())
+  available_versions = []
+  for version in supported_versions:
+    # Checking vs%s_install environment variables.
+    # For example, vs2019_install could have the value
+    # "C:\Program Files (x86)\Microsoft Visual Studio\2019\Community".
+    # Only vs2017_install and vs2019_install are supported.
+    path = os.environ.get('vs%s_install' % version)
+    if path and os.path.exists(path):
+      available_versions.append(version)
+      break
+    # Detecting VS under possible paths.
+    path = os.path.expandvars('%ProgramFiles(x86)%' +
+                              '/Microsoft Visual Studio/%s' % version)
+    if path and any(
+        os.path.exists(os.path.join(path, edition))
+        for edition in ('Enterprise', 'Professional', 'Community', 'Preview',
+                        'BuildTools')):
+      available_versions.append(version)
+      break
+
+  if not available_versions:
+    raise Exception('No supported Visual Studio can be found.'
+                    ' Supported versions are: %s.' % supported_versions_str)
+  return available_versions[0]
+
+
+def DetectVisualStudioPath():
+  """Return path to the installed Visual Studio.
+  """
+
+  # Note that this code is used from
+  # build/toolchain/win/setup_toolchain.py as well.
+  version_as_year = GetVisualStudioVersion()
+
+  # The VC++ >=2017 install location needs to be located using COM instead of
+  # the registry. For details see:
+  # https://blogs.msdn.microsoft.com/heaths/2016/09/15/changes-to-visual-studio-15-setup/
+  # For now we use a hardcoded default with an environment variable override.
+  for path in (
+      os.environ.get('vs%s_install' % version_as_year),
+      os.path.expandvars('%ProgramFiles(x86)%' +
+                         '/Microsoft Visual Studio/%s/Enterprise' %
+                         version_as_year),
+      os.path.expandvars('%ProgramFiles(x86)%' +
+                         '/Microsoft Visual Studio/%s/Professional' %
+                         version_as_year),
+      os.path.expandvars('%ProgramFiles(x86)%' +
+                         '/Microsoft Visual Studio/%s/Community' %
+                         version_as_year),
+      os.path.expandvars('%ProgramFiles(x86)%' +
+                         '/Microsoft Visual Studio/%s/Preview' %
+                         version_as_year),
+      os.path.expandvars('%ProgramFiles(x86)%' +
+                         '/Microsoft Visual Studio/%s/BuildTools' %
+                         version_as_year)):
+    if path and os.path.exists(path):
+      return path
+
+  raise Exception('Visual Studio Version %s not found.' % version_as_year)
+
+
+def _CopyRuntimeImpl(target, source, verbose=True):
+  """Copy |source| to |target| if it doesn't already exist or if it needs to be
+  updated (comparing last modified time as an approximate float match as for
+  some reason the values tend to differ by ~1e-07 despite being copies of the
+  same file... https://crbug.com/603603).
+  """
+  if (os.path.isdir(os.path.dirname(target)) and
+      (not os.path.isfile(target) or
+       abs(os.stat(target).st_mtime - os.stat(source).st_mtime) >= 0.01)):
+    if verbose:
+      print('Copying %s to %s...' % (source, target))
+    if os.path.exists(target):
+      # Make the file writable so that we can delete it now, and keep it
+      # readable.
+      os.chmod(target, stat.S_IWRITE | stat.S_IREAD)
+      os.unlink(target)
+    shutil.copy2(source, target)
+    # Make the file writable so that we can overwrite or delete it later,
+    # keep it readable.
+    os.chmod(target, stat.S_IWRITE | stat.S_IREAD)
+
+def _SortByHighestVersionNumberFirst(list_of_str_versions):
+  """This sorts |list_of_str_versions| according to version number rules
+  so that version "1.12" is higher than version "1.9". Does not work
+  with non-numeric versions like 1.4.a8 which will be higher than
+  1.4.a12. It does handle the versions being embedded in file paths.
+  """
+  def to_int_if_int(x):
+    try:
+      return int(x)
+    except ValueError:
+      return x
+
+  def to_number_sequence(x):
+    part_sequence = re.split(r'[\\/\.]', x)
+    return [to_int_if_int(x) for x in part_sequence]
+
+  list_of_str_versions.sort(key=to_number_sequence, reverse=True)
+
+
+def _CopyUCRTRuntime(target_dir, source_dir, target_cpu, suffix):
+  """Copy both the msvcp and vccorlib runtime DLLs, only if the target doesn't
+  exist, but the target directory does exist."""
+  if target_cpu == 'arm64':
+    # Windows ARM64 VCRuntime is located at {toolchain_root}/VC/Redist/MSVC/
+    # {x.y.z}/[debug_nonredist/]arm64/Microsoft.VC14x.CRT/.
+    # Select VC toolset directory based on Visual Studio version
+    vc_redist_root = FindVCRedistRoot()
+    if suffix.startswith('.'):
+      vc_toolset_dir = 'Microsoft.{}.CRT' \
+         .format(MSVC_TOOLSET_VERSION[GetVisualStudioVersion()])
+      source_dir = os.path.join(vc_redist_root,
+                                'arm64', vc_toolset_dir)
+    else:
+      vc_toolset_dir = 'Microsoft.{}.DebugCRT' \
+         .format(MSVC_TOOLSET_VERSION[GetVisualStudioVersion()])
+      source_dir = os.path.join(vc_redist_root, 'debug_nonredist',
+                                'arm64', vc_toolset_dir)
+  file_parts = ('msvcp140', 'vccorlib140', 'vcruntime140')
+  if target_cpu == 'x64' and GetVisualStudioVersion() != '2017':
+    file_parts = file_parts + ('vcruntime140_1', )
+  for file_part in file_parts:
+    dll = file_part + suffix
+    target = os.path.join(target_dir, dll)
+    source = os.path.join(source_dir, dll)
+    _CopyRuntimeImpl(target, source)
+  # Copy the UCRT files from the Windows SDK. This location includes the
+  # api-ms-win-crt-*.dll files that are not found in the Windows directory.
+  # These files are needed for component builds. If WINDOWSSDKDIR is not set
+  # use the default SDK path. This will be the case when
+  # DEPOT_TOOLS_WIN_TOOLCHAIN=0 and vcvarsall.bat has not been run.
+  win_sdk_dir = os.path.normpath(
+      os.environ.get('WINDOWSSDKDIR',
+                     os.path.expandvars('%ProgramFiles(x86)%'
+                                        '\\Windows Kits\\10')))
+  # ARM64 doesn't have a redist for the ucrt DLLs because they are always
+  # present in the OS.
+  if target_cpu != 'arm64':
+    # Starting with the 10.0.17763 SDK the ucrt files are in a version-named
+    # directory - this handles both cases.
+    redist_dir = os.path.join(win_sdk_dir, 'Redist')
+    version_dirs = glob.glob(os.path.join(redist_dir, '10.*'))
+    if len(version_dirs) > 0:
+      _SortByHighestVersionNumberFirst(version_dirs)
+      redist_dir = version_dirs[0]
+    ucrt_dll_dirs = os.path.join(redist_dir, 'ucrt', 'DLLs', target_cpu)
+    ucrt_files = glob.glob(os.path.join(ucrt_dll_dirs, 'api-ms-win-*.dll'))
+    assert len(ucrt_files) > 0
+    for ucrt_src_file in ucrt_files:
+      file_part = os.path.basename(ucrt_src_file)
+      ucrt_dst_file = os.path.join(target_dir, file_part)
+      _CopyRuntimeImpl(ucrt_dst_file, ucrt_src_file, False)
+  # We must copy ucrtbase.dll for x64/x86, and ucrtbased.dll for all CPU types.
+  if target_cpu != 'arm64' or not suffix.startswith('.'):
+    if not suffix.startswith('.'):
+      # ucrtbased.dll is located at {win_sdk_dir}/bin/{a.b.c.d}/{target_cpu}/
+      # ucrt/.
+      sdk_bin_root = os.path.join(win_sdk_dir, 'bin')
+      sdk_bin_sub_dirs = glob.glob(os.path.join(sdk_bin_root, '10.*'))
+      # Select the most recent SDK if there are multiple versions installed.
+      _SortByHighestVersionNumberFirst(sdk_bin_sub_dirs)
+      for directory in sdk_bin_sub_dirs:
+        sdk_redist_root_version = os.path.join(sdk_bin_root, directory)
+        if not os.path.isdir(sdk_redist_root_version):
+          continue
+        source_dir = os.path.join(sdk_redist_root_version, target_cpu, 'ucrt')
+        break
+    _CopyRuntimeImpl(os.path.join(target_dir, 'ucrtbase' + suffix),
+                     os.path.join(source_dir, 'ucrtbase' + suffix))
+
+
+def FindVCComponentRoot(component):
+  """Find the most recent Tools or Redist or other directory in an MSVC install.
+  Typical results are {toolchain_root}/VC/{component}/MSVC/{x.y.z}. The {x.y.z}
+  version number part changes frequently so the highest version number found is
+  used.
+  """
+
+  SetEnvironmentAndGetRuntimeDllDirs()
+  assert ('GYP_MSVS_OVERRIDE_PATH' in os.environ)
+  vc_component_msvc_root = os.path.join(os.environ['GYP_MSVS_OVERRIDE_PATH'],
+      'VC', component, 'MSVC')
+  vc_component_msvc_contents = glob.glob(
+      os.path.join(vc_component_msvc_root, '14.*'))
+  # Select the most recent toolchain if there are several.
+  _SortByHighestVersionNumberFirst(vc_component_msvc_contents)
+  for directory in vc_component_msvc_contents:
+    if os.path.isdir(directory):
+      return directory
+  raise Exception('Unable to find the VC %s directory.' % component)
+
+
+def FindVCRedistRoot():
+  """In >=VS2017, Redist binaries are located in
+  {toolchain_root}/VC/Redist/MSVC/{x.y.z}/{target_cpu}/.
+
+  This returns the '{toolchain_root}/VC/Redist/MSVC/{x.y.z}/' path.
+  """
+  return FindVCComponentRoot('Redist')
+
+
+def _CopyRuntime(target_dir, source_dir, target_cpu, debug):
+  """Copy the VS runtime DLLs, only if the target doesn't exist, but the target
+  directory does exist. Handles VS 2015, 2017 and 2019."""
+  suffix = 'd.dll' if debug else '.dll'
+  # VS 2015, 2017 and 2019 use the same CRT DLLs.
+  _CopyUCRTRuntime(target_dir, source_dir, target_cpu, suffix)
+
+
+def CopyDlls(target_dir, configuration, target_cpu):
+  """Copy the VS runtime DLLs into the requested directory as needed.
+
+  configuration is one of 'Debug' or 'Release'.
+  target_cpu is one of 'x86', 'x64' or 'arm64'.
+
+  The debug configuration gets both the debug and release DLLs; the
+  release config only the latter.
+  """
+  vs_runtime_dll_dirs = SetEnvironmentAndGetRuntimeDllDirs()
+  if not vs_runtime_dll_dirs:
+    return
+
+  x64_runtime, x86_runtime, arm64_runtime = vs_runtime_dll_dirs
+  if target_cpu == 'x64':
+    runtime_dir = x64_runtime
+  elif target_cpu == 'x86':
+    runtime_dir = x86_runtime
+  elif target_cpu == 'arm64':
+    runtime_dir = arm64_runtime
+  else:
+    raise Exception('Unknown target_cpu: ' + target_cpu)
+  _CopyRuntime(target_dir, runtime_dir, target_cpu, debug=False)
+  if configuration == 'Debug':
+    _CopyRuntime(target_dir, runtime_dir, target_cpu, debug=True)
+  _CopyDebugger(target_dir, target_cpu)
+
+
+def _CopyDebugger(target_dir, target_cpu):
+  """Copy dbghelp.dll and dbgcore.dll into the requested directory as needed.
+
+  target_cpu is one of 'x86', 'x64' or 'arm64'.
+
+  dbghelp.dll is used when Chrome needs to symbolize stacks. Copying this file
+  from the SDK directory avoids using the system copy of dbghelp.dll which then
+  ensures compatibility with recent debug information formats, such as VS
+  2017 /debug:fastlink PDBs.
+
+  dbgcore.dll is needed when using some functions from dbghelp.dll (like
+  MinidumpWriteDump).
+  """
+  win_sdk_dir = SetEnvironmentAndGetSDKDir()
+  if not win_sdk_dir:
+    return
+
+  # List of debug files that should be copied, the first element of the tuple is
+  # the name of the file and the second indicates if it's optional.
+  debug_files = [('dbghelp.dll', False), ('dbgcore.dll', True)]
+  # The UCRT is not a redistributable component on arm64.
+  if target_cpu != 'arm64':
+    debug_files.extend([('api-ms-win-downlevel-kernel32-l2-1-0.dll', False),
+                        ('api-ms-win-eventing-provider-l1-1-0.dll', False)])
+  for debug_file, is_optional in debug_files:
+    full_path = os.path.join(win_sdk_dir, 'Debuggers', target_cpu, debug_file)
+    if not os.path.exists(full_path):
+      if is_optional:
+        continue
+      else:
+        raise Exception('%s not found in "%s"\r\nYou must install'
+                        'Windows 10 SDK version 10.0.19041.0 including the '
+                        '"Debugging Tools for Windows" feature.' %
+                        (debug_file, full_path))
+    target_path = os.path.join(target_dir, debug_file)
+    _CopyRuntimeImpl(target_path, full_path)
+
+
+def _GetDesiredVsToolchainHashes():
+  """Load a list of SHA1s corresponding to the toolchains that we want installed
+  to build with."""
+  # Third parties that do not have access to the canonical toolchain can map
+  # canonical toolchain version to their own toolchain versions.
+  toolchain_hash_mapping_key = 'GYP_MSVS_HASH_%s' % TOOLCHAIN_HASH
+  return [os.environ.get(toolchain_hash_mapping_key, TOOLCHAIN_HASH)]
+
+
+def ShouldUpdateToolchain():
+  """Check if the toolchain should be upgraded."""
+  if not os.path.exists(json_data_file):
+    return True
+  with open(json_data_file, 'r') as tempf:
+    toolchain_data = json.load(tempf)
+  version = toolchain_data['version']
+  env_version = GetVisualStudioVersion()
+  # If there's a mismatch between the version set in the environment and the one
+  # in the json file then the toolchain should be updated.
+  return version != env_version
+
+
+def Update(force=False, no_download=False):
+  """Requests an update of the toolchain to the specific hashes we have at
+  this revision. The update outputs a .json of the various configuration
+  information required to pass to gyp which we use in |GetToolchainDir()|.
+  If no_download is true then the toolchain will be configured if present but
+  will not be downloaded.
+  """
+  if force != False and force != '--force':
+    print('Unknown parameter "%s"' % force, file=sys.stderr)
+    return 1
+  if force == '--force' or os.path.exists(json_data_file):
+    force = True
+
+  depot_tools_win_toolchain = \
+      bool(int(os.environ.get('DEPOT_TOOLS_WIN_TOOLCHAIN', '1')))
+  if (_HostIsWindows() or force) and depot_tools_win_toolchain:
+    import find_depot_tools
+    depot_tools_path = find_depot_tools.add_depot_tools_to_path()
+
+    # On Linux, the file system is usually case-sensitive while the Windows
+    # SDK only works on case-insensitive file systems.  If it doesn't already
+    # exist, set up a ciopfs fuse mount to put the SDK in a case-insensitive
+    # part of the file system.
+    toolchain_dir = os.path.join(depot_tools_path, 'win_toolchain', 'vs_files')
+    # For testing this block, unmount existing mounts with
+    # fusermount -u third_party/depot_tools/win_toolchain/vs_files
+    if sys.platform.startswith('linux') and not os.path.ismount(toolchain_dir):
+      import distutils.spawn
+      ciopfs = distutils.spawn.find_executable('ciopfs')
+      if not ciopfs:
+        # ciopfs not found in PATH; try the one downloaded from the DEPS hook.
+        ciopfs = os.path.join(script_dir, 'ciopfs')
+      if not os.path.isdir(toolchain_dir):
+        os.mkdir(toolchain_dir)
+      if not os.path.isdir(toolchain_dir + '.ciopfs'):
+        os.mkdir(toolchain_dir + '.ciopfs')
+      # Without use_ino, clang's #pragma once and Wnonportable-include-path
+      # both don't work right, see https://llvm.org/PR34931
+      # use_ino doesn't slow down builds, so it seems there's no drawback to
+      # just using it always.
+      subprocess.check_call([
+          ciopfs, '-o', 'use_ino', toolchain_dir + '.ciopfs', toolchain_dir])
+
+    get_toolchain_args = [
+        sys.executable,
+        os.path.join(depot_tools_path,
+                    'win_toolchain',
+                    'get_toolchain_if_necessary.py'),
+        '--output-json', json_data_file,
+      ] + _GetDesiredVsToolchainHashes()
+    if force:
+      get_toolchain_args.append('--force')
+    if no_download:
+      get_toolchain_args.append('--no-download')
+    subprocess.check_call(get_toolchain_args)
+
+  return 0
+
+
+def NormalizePath(path):
+  while path.endswith('\\'):
+    path = path[:-1]
+  return path
+
+
+def SetEnvironmentAndGetSDKDir():
+  """Gets location information about the current sdk (must have been
+  previously updated by 'update'). This is used for the GN build."""
+  SetEnvironmentAndGetRuntimeDllDirs()
+
+  # If WINDOWSSDKDIR is not set, search the default SDK path and set it.
+  if not 'WINDOWSSDKDIR' in os.environ:
+    default_sdk_path = os.path.expandvars('%ProgramFiles(x86)%'
+                                          '\\Windows Kits\\10')
+    if os.path.isdir(default_sdk_path):
+      os.environ['WINDOWSSDKDIR'] = default_sdk_path
+
+  return NormalizePath(os.environ['WINDOWSSDKDIR'])
+
+
+def GetToolchainDir():
+  """Gets location information about the current toolchain (must have been
+  previously updated by 'update'). This is used for the GN build."""
+  runtime_dll_dirs = SetEnvironmentAndGetRuntimeDllDirs()
+  win_sdk_dir = SetEnvironmentAndGetSDKDir()
+
+  print('''vs_path = %s
+sdk_path = %s
+vs_version = %s
+wdk_dir = %s
+runtime_dirs = %s
+''' % (ToGNString(NormalizePath(os.environ['GYP_MSVS_OVERRIDE_PATH'])),
+       ToGNString(win_sdk_dir), ToGNString(GetVisualStudioVersion()),
+       ToGNString(NormalizePath(os.environ.get('WDK_DIR', ''))),
+       ToGNString(os.path.pathsep.join(runtime_dll_dirs or ['None']))))
+
+
+def main():
+  commands = {
+      'update': Update,
+      'get_toolchain_dir': GetToolchainDir,
+      'copy_dlls': CopyDlls,
+  }
+  if len(sys.argv) < 2 or sys.argv[1] not in commands:
+    print('Expected one of: %s' % ', '.join(commands), file=sys.stderr)
+    return 1
+  if sys.argv[1] == 'copy_dlls':
+    return 0
+  return commands[sys.argv[1]](*sys.argv[2:])
+
+
+if __name__ == '__main__':
+  sys.exit(main())