Fix ExhaustMemory on clang.

base/process/memory_unittest.cc

 // 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.
 
 #define _CRT_SECURE_NO_WARNINGS
 
 #include "base/process/memory.h"
 
 #include <stddef.h>
 
@@ skipping 81 matching lines @@
 namespace {
 #if defined(OS_WIN)
 // Windows raises an exception rather than using LOG(FATAL) in order to make the
 // exit code unique to OOM.
 const char* kOomRegex = "";
 const int kExitCode = base::win::kOomExceptionCode;
 #else
 const char* kOomRegex = "Out of memory";
 const int kExitCode = 1;
 #endif
+
+// See corresponding function in content/renderer/render_frame_impl.cc
+NOINLINE void ExhaustMemory() {
+  volatile void* ptr = nullptr;
+  do {
+    ptr = malloc(0x10000000);
+    base::debug::Alias(&ptr);
+  } while (ptr);
+}
+
 }  // namespace
 
 class OutOfMemoryTest : public testing::Test {
  public:
   OutOfMemoryTest()
     : value_(NULL),
     // Make test size as large as possible minus a few pages so
     // that alignment or other rounding doesn't make it wrap.
     test_size_(std::numeric_limits<std::size_t>::max() - 12 * 1024),
     // A test size that is > 2Gb and will cause the allocators to reject
@@ skipping 14 matching lines @@
   void SetUpInDeathAssert() {
     // Must call EnableTerminationOnOutOfMemory() because that is called from
     // chrome's main function and therefore hasn't been called yet.
     // Since this call may result in another thread being created and death
     // tests shouldn't be started in a multithread environment, this call
     // should be done inside of the ASSERT_DEATH.
     base::EnableTerminationOnOutOfMemory();
   }
 };
 
+TEST_F(OutOfMemoryDeathTest, Exhaust) {
+  ASSERT_EXIT({
+      SetUpInDeathAssert();
+      ExhaustMemory();
+    }, testing::ExitedWithCode(kExitCode), kOomRegex);
+}

[Nico, 2017/01/26 17:56:53]

do we really need this test? it duplicates the function under test and it adds a
death test, which both seems a bit suboptimal. i'd either revert changes to this
file, or make it so that the old cold calls the function that's actually being
tested here.

[Will Harris, 2017/01/26 18:12:44]

I'm not sure I totally understand what you mean by "duplicates the function
under test", but alternatively I could move the test to a browser test and
navigate to the URL instead, would that suffice?

Historically we've been okay with death tests for the memory code (see the rest
of the file), but I agree it's non-optimal to duplicate the ExhaustMemory code
in two places.

+
 TEST_F(OutOfMemoryDeathTest, New) {
   ASSERT_EXIT({
       SetUpInDeathAssert();
       value_ = operator new(test_size_);
     }, testing::ExitedWithCode(kExitCode), kOomRegex);
 }
 
 TEST_F(OutOfMemoryDeathTest, NewArray) {
   ASSERT_EXIT({
       SetUpInDeathAssert();
@@ skipping 288 matching lines @@
   bytes = static_cast<const char*>(value_);
   for (size_t i = 0; i < (kSafeCallocItems * kSafeCallocSize); ++i)
     EXPECT_EQ(0, bytes[i]);
   free(value_);
 
   EXPECT_FALSE(base::UncheckedCalloc(1, test_size_, &value_));
   EXPECT_TRUE(value_ == NULL);
 }
 #endif  // !defined(OS_OPENBSD) && BUILDFLAG(ENABLE_WIN_ALLOCATOR_SHIM_TESTS) &&
         // !defined(MEMORY_TOOL_REPLACES_ALLOCATOR)