Include PowerShell in Windows PATH, if available.

slave/run_slave.py

 #!/usr/bin/env python
 # Copyright (c) 2012 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.
 
 """ Initialize the environment variables and start the buildbot slave.
 """
 
 import os
 import shutil
@@ skipping 39 matching lines @@
   """Issue reboot command according to platform type."""
   if sys.platform.startswith('win'):
     subprocess.call(['shutdown', '-r', '-f', '-t', '1'])
   elif sys.platform in ('darwin', 'posix', 'linux2'):
     subprocess.call(['sudo', 'shutdown', '-r', 'now'])
   else:
     raise NotImplementedError('Implement IssueReboot function '
                               'for %s' % sys.platform)
 
 
-def SigTerm(*args):
+def SigTerm(*_args):
   """Receive a SIGTERM and do nothing."""
   Log('SigTerm: Received SIGTERM, doing nothing.')
 
 
 def UpdateSignals():
   """Override the twisted SIGTERM handler with our own.
 
   Ensure that the signal module is available and do nothing if it is not.
   """
   try:
@@ skipping 355 matching lines @@
   python_path.append(os.path.join(BUILD_DIR, 'third_party', bb_ver))
   python_path.append(os.path.join(BUILD_DIR, 'third_party', tw_ver))
   sys.path = python_path[-2:] + sys.path
 
   os.environ['PYTHONPATH'] = (
       os.pathsep.join(python_path) + os.pathsep + os.environ['PYTHONPATH'])
 
   os.environ['CHROME_HEADLESS'] = '1'
   os.environ['PAGER'] = 'cat'
 
+  # Split the path into its components.
+  path_components = os.environ['PATH'].split(os.pathsep)
+  # This function identifies a PATH component that has the supplied phrase in
+  # one of its directories.
+  def get_path_component_containing(phrase):

[agable, 2016/06/24 18:29:16]

This function is only used once, and is defined nearly a hundred lines from
where it is used (albeit, most of those lines are constants). Why make it a
function at all? The name of the function also doesn't denote that it returns
the *first* path component containing the phrase. Honestly I'd just inline it
and comment the loop.

[dnj (Google), 2016/06/24 18:39:59]

My thought was that it is OS-independent and seemed generically useful, so I
wouldn't mind porting more path-derivations over to this method in the future.
However, agreed, I'll go ahead and move it locally.

Actually I'll just switch over to straightforward 'which / dirname'. Why not?

+    phrase = phrase.lower()
+    for c in path_components:
+      if any(phrase == d.lower() for d in c.split(os.sep)):
+        return [c]
+    return []
+
   # Platform-specific initialization.
-
   if sys.platform.startswith('win'):
     # list of all variables that we want to keep
     env_var = [
         'APPDATA',
         'BUILDBOT_ARCHIVE_FORCE_SSH',
         'CHROME_HEADLESS',
         'CHROMIUM_BUILD',
         'COMMONPROGRAMFILES',
         'COMMONPROGRAMFILES(X86)',
         'COMMONPROGRAMW6432',
@@ skipping 29 matching lines @@
         'USERNAME',
         'USERDOMAIN',
         'USERPROFILE',
         'VS100COMNTOOLS',
         'VS110COMNTOOLS',
         'WINDIR',
     ]
 
     remove_all_vars_except(os.environ, env_var)
 
-    # Extend the env variables with the chrome-specific settings.
+    # Extend the env variables with the chrome-specific settings. Tailor the
+    # slave process' (and derivative tasks') PATH environment variable.
     slave_path = [
         depot_tools,
         # Reuse the python executable used to start this script.
         os.path.dirname(sys.executable),
         os.path.join(os.environ['SYSTEMROOT'], 'system32'),
         os.path.join(os.environ['SYSTEMROOT'], 'system32', 'WBEM'),
         # Use os.sep to make this absolute, not relative.
         os.path.join(os.environ['SYSTEMDRIVE'], os.sep, 'Program Files',
                      '7-Zip'),
         # TODO(hinoka): Remove this when its no longer needed crbug.com/481695
         os.path.join(os.environ['SYSTEMDRIVE'], os.sep, 'cmake', 'bin'),
     ]
+
+    # Include Windows PowerShell in PATH, if defined. It does this by looking
+    # through the system path for an element containing a directory named
+    # "WindowsPowerShell", which is assumed to be the component adding
+    # PowerShell to the PATH.
+    slave_path += get_path_component_containing('WindowsPowerShell')
+
     # build_internal/tools contains tools we can't redistribute.
     tools = os.path.join(ROOT_DIR, 'build_internal', 'tools')
     if os.path.isdir(tools):
       slave_path.append(os.path.abspath(tools))
     os.environ['PATH'] = os.pathsep.join(slave_path)
     os.environ['LOGNAME'] = os.environ['USERNAME']
 
   elif sys.platform in ('darwin', 'posix', 'linux2'):
     # list of all variables that we want to keep
     env_var = [
@@ skipping 116 matching lines @@
     if subprocess.call(
         [GetGClientPath(), 'sync', '--force', '--break_repo_locks'],
         env=EnvWithDepotTools()) != 0:
       print >> sys.stderr, (
           '(%s) `gclient sync` failed; proceeding anyway...' % sys.argv[0])
     os.execv(sys.executable, [sys.executable] + sys.argv + [skip_sync_arg])
 
   # Remove skip_sync_arg from arg list.  Needed because twistd.
   sys.argv.remove(skip_sync_arg)
   main()