Fix coloring madness in depot_tools.

setup_color.py

+#!/usr/bin/env python
+# Copyright (c) 2016 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.
+
+import os
+import sys
+from third_party import colorama
+
+IS_TTY = None
+OUT_TYPE = 'unknown'
+
+def init():
+  should_wrap = True
+  global IS_TTY, OUT_TYPE
+  IS_TTY = sys.stdout.isatty()
+  if IS_TTY:
+    OUT_TYPE = 'console'

[iannucci, 2016/04/02 06:08:20]

yay, we detected it via the normal mechanism! This can happen when python is
attached directly to a tty (shell, cmd).

[brucedawson, 2016/04/02 20:42:50]

Can you make this explanation and others comments in the code? Otherwise this
will seem like black magic to the next person who looks at this code.

[iannucci, 2016/04/02 23:45:34]

Yeah should have done that in the first place :). Done.

+  elif sys.platform.startswith('win'):
+    OUT_TYPE = 'pipe'

[iannucci, 2016/04/02 06:08:21]

Assume it's a pipe

+
+    import msvcrt
+    import ctypes
+    h = msvcrt.get_osfhandle(sys.stdout.fileno())

[iannucci, 2016/04/02 06:08:20]

h is the win32 HANDLE for stdout.

+    ftype = ctypes.windll.kernel32.GetFileType(h)
+    if ftype == 2: # FILE_TYPE_CHAR

[iannucci, 2016/04/02 06:08:20]

This happens when were running in cmd but via some `git command` (which is
git->bash->command). I'm not exactly sure why 'isatty' doesn't detect this case,
but it definitely doesn't.

+      OUT_TYPE = 'console (cmd via msys)'
+      IS_TTY = True
+    elif ftype == 3: # FILE_TYPE_PIPE

[iannucci, 2016/04/02 06:08:21]

This happens if we're running under bash in interactive-mode (e.g. under the
`git bash` shell).

+      OUT_TYPE = 'pipe'
+      def NT_SUCCESS(status):
+        if status >= 0 and status <= 0x3FFFFFFF:
+          return True
+        if status >= 0x40000000 and status <= 0x7FFFFFFF:
+          return True
+        return False
+
+      class UNICODE_STRING(ctypes.Structure):
+        _fields_ = [('Length', ctypes.c_ushort),
+                    ('MaximumLength', ctypes.c_ushort),
+                    ('Buffer', ctypes.c_wchar_p)]
+
+      class OBJECT_NAME_INFORMATION(ctypes.Structure):
+        _fields_ = [('Name', UNICODE_STRING),
+                    ('NameBuffer', ctypes.c_wchar_p)]

[iannucci, 2016/04/02 06:08:21]

These are all defined in the MSDN documentation under the same names.

+
+      # 1: ObjectNameInformation
+      buf = ctypes.create_string_buffer('\0', 1024)
+      if NT_SUCCESS(ctypes.windll.ntdll.NtQueryObject(h, 1, buf, len(buf)-2,

[iannucci, 2016/04/02 06:08:21]

Ask NT what the name of thing attached to the stdout HANDLE is. ctypes is
awesome.

GetFileInformationByHandleEx is another way to get this, but it's only available
on Vista+... which should probably be OK, but the method above is the way that
git-on-windows does it so *shrug*.

+                    None)):
+        # MSYS console, but not an MSYS pipe
+        out = OBJECT_NAME_INFORMATION.from_buffer(buf)
+        name = out.Name.Buffer.split('\\')[-1]
+        IS_TTY = name.startswith('msys-') and '-pty' in name

[iannucci, 2016/04/02 06:08:21]

The full name is something like "\Device\NamedPipe\msys-*-pty*", so we just care
about the last bit.

If it's in the msys shell and like `some_process | cat`, some_process will see
just a randomized pipe name (not a pty).

+        should_wrap = False

[iannucci, 2016/04/02 06:08:21]

either way, we don't need to do the weird win32 syscalls to change the console
state.

+        if IS_TTY:
+          OUT_TYPE = 'console (msys)'
+  else:

[iannucci, 2016/04/02 06:08:20]

Not on windows, so isatty is reliable.

+    OUT_TYPE = 'pipe'
+
+  colorama.init(wrap=should_wrap)
+
+if __name__ == '__main__':
+  init()
+  print 'IS_TTY:', IS_TTY
+  print 'OUT_TYPE:', OUT_TYPE