Mojo: Fix Options struct alignment checking on Windows.

R=darin@chromium.org

Review URL: https://codereview.chromium.org/422093002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@286026 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 14 insertions, 18 deletions

diff --git a/mojo/system/memory.cc b/mojo/system/memory.cc
index 9aa0f78..15f83f4 100644
--- a/mojo/system/memory.cc
+++ b/mojo/system/memory.cc
@@ -39,20 +39,6 @@ template void MOJO_SYSTEM_IMPL_EXPORT CheckUserPointer<4, 4>(
     const void*);
 template void MOJO_SYSTEM_IMPL_EXPORT CheckUserPointer<8, 8>(
     const void*);
-// Notwithstanding the comments above about MSVS, whenever we expect an
-// alignment of 8 for something of size 4, it's due to an explicit (e.g.,
-// #pragma align) alignment specification, which MSVS *does* respect. We want
-// this in particular to check that various Options structs are aligned.
-#if defined(COMPILER_MSVC) && defined(ARCH_CPU_32_BITS)
-template <>
-void MOJO_SYSTEM_IMPL_EXPORT CheckUserPointer<4, 8>(
-    const void* pointer) {
-  CHECK(pointer && reinterpret_cast<uintptr_t>(pointer) % 8 == 0);
-}
-#else
-template MOJO_SYSTEM_IMPL_EXPORT void CheckUserPointer<4, 8>(
-    const void*);
-#endif
 
 template <size_t size, size_t alignment>
 void MOJO_SYSTEM_IMPL_EXPORT CheckUserPointerWithCount(const void* pointer,
@@ -82,8 +68,21 @@ template void MOJO_SYSTEM_IMPL_EXPORT CheckUserPointerWithSize<1>(const void*,
                                                                   size_t);
 template void MOJO_SYSTEM_IMPL_EXPORT CheckUserPointerWithSize<4>(const void*,
                                                                   size_t);
+// Whereas the other |Check...()| functions are usually used with integral typs
+// or arrays of integral types, this one is used with Options structs for which
+// alignment has been explicitly been specified (using |MOJO_ALIGNAS()|), which
+// MSVS *does* respect.
+#if defined(COMPILER_MSVC) && defined(ARCH_CPU_32_BITS)
+template <>
+void MOJO_SYSTEM_IMPL_EXPORT CheckUserPointerWithSize<8>(const void* pointer,
+                                                         size_t size) {
+  CHECK(size == 0 ||
+        (!!pointer && reinterpret_cast<uintptr_t>(pointer) % 8 == 0));
+}
+#else
 template void MOJO_SYSTEM_IMPL_EXPORT CheckUserPointerWithSize<8>(const void*,
                                                                   size_t);
+#endif
 
 }  // namespace internal
 }  // namespace system
diff --git a/mojo/system/options_validation_unittest.cc b/mojo/system/options_validation_unittest.cc
index 615dac80..bf9570a 100644
--- a/mojo/system/options_validation_unittest.cc
+++ b/mojo/system/options_validation_unittest.cc
@@ -112,8 +112,6 @@ TEST(OptionsValidationTest, InvalidDeath) {
       { UserOptionsReader<TestOptions> reader(
             MakeUserPointer(reinterpret_cast<const TestOptions*>(1))); },
       kMemoryCheckFailedRegex);
-// TODO(vtl): Broken on Windows. Fix this!
-#if 0
   // Note: The current implementation checks the size only after checking the
   // alignment versus that required for the |uint32_t| size, so it won't die in
   // the expected way if you pass, e.g., 4. So we have to manufacture a valid
@@ -121,14 +119,13 @@ TEST(OptionsValidationTest, InvalidDeath) {
   EXPECT_DEATH_IF_SUPPORTED(
       {
         uint32_t buffer[100] = {};
-        TestOptions* options = (reinterpret_cast<uintptr_t>(buffer) % 4 == 0) ?
+        TestOptions* options = (reinterpret_cast<uintptr_t>(buffer) % 8 == 0) ?
                                    reinterpret_cast<TestOptions*>(&buffer[1]) :
                                    reinterpret_cast<TestOptions*>(&buffer[0]);
         options->struct_size = static_cast<uint32_t>(sizeof(TestOptions));
         UserOptionsReader<TestOptions> reader(MakeUserPointer(options));
       },
       kMemoryCheckFailedRegex);
-#endif
 }
 
 }  // namespace