Stop gyp_chromium prior to mass DLL copies on error

build/vs_toolchain.py

 #!/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.
 
 import glob
 import json
 import os
 import pipes
 import shutil
@@ skipping 135 matching lines @@
   vs_version = GetVisualStudioVersion()
   if vs_version == '2013':
     return '120'
   elif vs_version == '2015':
     return '140'
   else:
     raise ValueError('Unexpected GYP_MSVS_VERSION')
 
 
 def _CopyRuntimeImpl(target, source, verbose=True):
-  """Copy |source| to |target| if it doesn't already exist or if it
-  needs to be updated.
+  """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
-      os.stat(target).st_mtime != os.stat(source).st_mtime)):
+       abs(os.stat(target).st_mtime - os.stat(source).st_mtime) >= 0.01)):

[scottmg, 2016/04/18 16:48:39]

Gah! Why the heck is mtime a float anyway :/

[gab, 2016/04/18 16:58:51]

I know, right..! Casting to int() and doing strict equal also works if you
prefer but I wasn't sure if the float resolution could ever be somewhat
useful...

[brucedawson, 2016/04/18 18:25:17]

WTF? There's something weird going on. When I run:

  os.stat("PRESUBMIT.PY")

it says st_mtime=1460399946L, but when I run:

  os.stat("PRESUBMIT.PY").st_mtime

it says "1460399946.7608104"

That inconsistency is disturbing - I don't understand it.

Using the C stat() function gives the answer 1460399946, but using GetFileTime
gives sub-second precision that roughly matches Python.

So...

It is right and proper for Python to use float (which is actually double) for
the file times. But I don't understand why when I print the entire stat() result
it says it is returning a long integer. And I don't understand why st_mtime
varies when the file is copied.

BTW, 1e7 is the resolution of FILETIME in Windows, so the error is one unit in
the last place.

Also, I don't know why my FILETIME results don't perfectly match Python's,
although that may be because I didn't add timezone conversion code.

     if verbose:
       print 'Copying %s to %s...' % (source, target)
     if os.path.exists(target):
       os.unlink(target)
     shutil.copy2(source, target)
 
 
 def _CopyRuntime2013(target_dir, source_dir, dll_pattern):
   """Copy both the msvcr and msvcp runtime DLLs, only if the target doesn't
   exist, but the target directory does exist."""
   for file_part in ('p', 'r'):
     dll = dll_pattern % file_part
     target = os.path.join(target_dir, dll)
     source = os.path.join(source_dir, dll)
     _CopyRuntimeImpl(target, source)
 
 
 def _CopyRuntime2015(target_dir, source_dir, dll_pattern, suffix):
   """Copy both the msvcp and vccorlib runtime DLLs, only if the target doesn't
   exist, but the target directory does exist."""
   for file_part in ('msvcp', 'vccorlib', 'vcruntime'):
     dll = dll_pattern % file_part
     target = os.path.join(target_dir, dll)
     source = os.path.join(source_dir, dll)
     _CopyRuntimeImpl(target, source)
   ucrt_src_dir = os.path.join(source_dir, 'api-ms-win-*.dll')
-  print 'Copying %s to %s...' % (ucrt_src_dir, target_dir)
   for ucrt_src_file in glob.glob(ucrt_src_dir):
     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)
   _CopyRuntimeImpl(os.path.join(target_dir, 'ucrtbase' + suffix),
                     os.path.join(source_dir, 'ucrtbase' + suffix))
 
 
 def _CopyRuntime(target_dir, source_dir, target_cpu, debug):
   """Copy the VS runtime DLLs, only if the target doesn't exist, but the target
@@ skipping 169 matching lines @@
       'copy_dlls': CopyDlls,
   }
   if len(sys.argv) < 2 or sys.argv[1] not in commands:
     print >>sys.stderr, 'Expected one of: %s' % ', '.join(commands)
     return 1
   return commands[sys.argv[1]](*sys.argv[2:])
 
 
 if __name__ == '__main__':
   sys.exit(main())