Stop gyp_chromium prior to mass DLL copies on error

build/vs_toolchain.py

Index: build/vs_toolchain.py
diff --git a/build/vs_toolchain.py b/build/vs_toolchain.py
index 12e86546870258eb3b366c9db43a3938e34512e0..1012216346806a9262ae7df3bdd53ed26abbdf13 100755
--- a/build/vs_toolchain.py
+++ b/build/vs_toolchain.py
@@ -153,12 +153,14 @@ def _VersionNumber():
 
 
 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):
@@ -185,7 +187,6 @@ def _CopyRuntime2015(target_dir, source_dir, dll_pattern, suffix):
     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)