win: Add and use GET_FUNCTION() and GET_FUNCTION_REQUIRED()

util/win/get_function_test.cc

Index: util/win/get_function_test.cc
diff --git a/util/win/get_function_test.cc b/util/win/get_function_test.cc
new file mode 100644
index 0000000000000000000000000000000000000000..a2217aef66ba35b90aa6afe043031bdf0c8d2694
--- /dev/null
+++ b/util/win/get_function_test.cc
@@ -0,0 +1,78 @@
+// Copyright 2015 The Crashpad Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+#include "util/win/get_function.h"
+
+#include <windows.h>
+#include <winternl.h>
+
+#include "gtest/gtest.h"
+
+namespace crashpad {
+namespace test {
+namespace {
+
+TEST(GetFunction, GetFunction) {
+  // Check equivalence of GET_FUNCTION_REQUIRED() with functions that are
+  // available in the SDK normally.
+  EXPECT_EQ(&GetProcAddress,
+            GET_FUNCTION_REQUIRED(L"kernel32.dll", GetProcAddress));
+  EXPECT_EQ(&LoadLibraryW,
+            GET_FUNCTION_REQUIRED(L"kernel32.dll", LoadLibraryW));
+
+  // Make sure that a function pointer retrieved by GET_FUNCTION_REQUIRED() can
+  // be called and that it works correctly.
+  const auto get_current_process_id =
+      GET_FUNCTION_REQUIRED(L"kernel32.dll", GetCurrentProcessId);
+  EXPECT_EQ(&GetCurrentProcessId, get_current_process_id);
+  ASSERT_TRUE(get_current_process_id);
+  EXPECT_EQ(GetCurrentProcessId(), get_current_process_id());
+
+  // GET_FUNCTION_REQUIRED() and GET_FUNCTION() should behave identically when
+  // the function is present.
+  EXPECT_EQ(get_current_process_id,
+            GET_FUNCTION(L"kernel32.dll", GetCurrentProcessId));
+
+  // Using a leading :: should also work.
+  EXPECT_EQ(get_current_process_id,
+            GET_FUNCTION(L"kernel32.dll", ::GetCurrentProcessId));
+  EXPECT_EQ(get_current_process_id,
+            GET_FUNCTION_REQUIRED(L"kernel32.dll", ::GetCurrentProcessId));
+
+  // Try a function that’s declared in the SDK’s headers but that has no import
+  // library.
+  EXPECT_TRUE(GET_FUNCTION_REQUIRED(L"ntdll.dll", RtlNtStatusToDosError));
+
+  // GetNamedPipeClientProcessId() is only available on Vista and later.
+  const auto get_named_pipe_client_process_id =
+      GET_FUNCTION(L"kernel32.dll", GetNamedPipeClientProcessId);
+  const DWORD version = GetVersion();
+  const DWORD major_version = LOBYTE(LOWORD(version));
+  EXPECT_EQ(major_version >= 6, get_named_pipe_client_process_id != nullptr);
+
+  // Test that GET_FUNCTION() can fail by trying a nonexistent library and a
+  // symbol that doesn’t exist in the specified library.
+  EXPECT_FALSE(GET_FUNCTION(L"not_a_real_library.dll", TerminateProcess));
+  EXPECT_FALSE(GET_FUNCTION(L"ntdll.dll", TerminateProcess));
+  EXPECT_FALSE(GET_FUNCTION(L"not_a_real_library.dll", ::TerminateProcess));
+  EXPECT_FALSE(GET_FUNCTION(L"ntdll.dll", ::TerminateProcess));
+
+  // Here it is!
+  EXPECT_TRUE(GET_FUNCTION(L"kernel32.dll", TerminateProcess));
+  EXPECT_TRUE(GET_FUNCTION(L"kernel32.dll", ::TerminateProcess));
+}
+
+}  // namespace
+}  // namespace test
+}  // namespace crashpad