Check for inputs not generated by deps

tools/gn/function_write_file.cc

 // Copyright (c) 2013 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.
 
 #include <iostream>
 #include <sstream>
 
 #include "base/files/file_util.h"
 #include "base/strings/string_split.h"
 #include "base/strings/string_util.h"
 #include "base/strings/utf_string_conversions.h"
 #include "tools/gn/err.h"
 #include "tools/gn/filesystem_utils.h"
 #include "tools/gn/functions.h"
 #include "tools/gn/input_file.h"
 #include "tools/gn/parse_tree.h"
 #include "tools/gn/scheduler.h"
 
 namespace functions {
 
 namespace {
 
 // On Windows, provide a custom implementation of base::WriteFile. Sometimes
-// the base version would fail, and this alternate implementation provides
-// additional logging. See http://crbug.com/468437
+// the base version fails, especially on the bots. The guess is that Windows
+// Defender or other antivirus programs still have the file open (after
+// checking for the read) when the write happens immediately after. This
+// version opens with FILE_SHARE_READ (normally not what you want when
+// replacing the entire contents of the file) which lets us continue even if
+// another program has the file open for reading. See http://crbug.com/468437
 #if defined(OS_WIN)
 int DoWriteFile(const base::FilePath& filename, const char* data, int size) {
   base::win::ScopedHandle file(::CreateFile(
       filename.value().c_str(),
       GENERIC_WRITE,
-      FILE_SHARE_READ,  // Not present in the base version, speculative fix.
+      FILE_SHARE_READ,
       NULL,
       CREATE_ALWAYS,
       0,
       NULL));
   if (!file.IsValid()) {
     PLOG(ERROR) << "CreateFile failed for path "
                   << base::UTF16ToUTF8(filename.value());
     return -1;
   }
 
@@ skipping 60 matching lines @@
   // Compute the file name and make sure it's in the output dir.
   const SourceDir& cur_dir = scope->GetSourceDir();
   SourceFile source_file = cur_dir.ResolveRelativeFile(args[0], err,
       scope->settings()->build_settings()->root_path_utf8());
   if (err->has_error())
     return Value();
   if (!EnsureStringIsInOutputDir(
           scope->settings()->build_settings()->build_dir(),
           source_file.value(), args[0].origin(), err))
     return Value();
+  g_scheduler->AddWrittenFile(source_file);  // Track that we wrote this file.
 
   // Compute output.
   std::ostringstream contents;
   if (args[1].type() == Value::LIST) {
     const std::vector<Value>& list = args[1].list_value();
     for (const auto& cur : list)
       contents << cur.ToString(false) << std::endl;
   } else {
     contents << args[1].ToString(false);
   }
@@ skipping 18 matching lines @@
   if (DoWriteFile(file_path, new_contents.c_str(), int_size)
       != int_size) {
     *err = Err(function->function(), "Unable to write file.",
                "I was writing \"" + FilePathToUTF8(file_path) + "\".");
     return Value();
   }
   return Value();
 }
 
 }  // namespace functions