win: Add WinMultiprocess for multiprocess Windows tests

test/win/win_multiprocess.cc

+// 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 "test/win/win_multiprocess.h"
+
+#include <shellapi.h>
+
+#include "base/logging.h"
+#include "base/scoped_generic.h"
+#include "base/strings/stringprintf.h"
+#include "base/strings/utf_string_conversions.h"
+#include "gtest/gtest.h"
+#include "util/stdlib/string_number_conversion.h"
+#include "util/string/split_string.h"
+#include "test/paths.h"
+
+namespace crashpad {
+namespace test {
+
+namespace {
+
+const char kIsMultiprocessChild[] = "--is-multiprocess-child";
+
+struct LocalFreeTraits {
+  static HLOCAL InvalidValue() { return nullptr; }
+  static void Free(HLOCAL mem) {
+    if (LocalFree(mem) != nullptr)
+      PLOG(ERROR) << "LocalFree";
+  }
+};
+
+using ScopedLocalFree = base::ScopedGeneric<HLOCAL, LocalFreeTraits>;
+
+bool GetSwitch(const char* switch_name, std::string* value) {
+  int num_args;
+  wchar_t** args = CommandLineToArgvW(GetCommandLine(), &num_args);
+  ScopedLocalFree scoped_args(args);  // Take ownership.
+  if (!args) {
+    PLOG(ERROR) << "couldn't parse command line";
+    return false;
+  }
+
+  std::string switch_name_with_equals(switch_name);
+  switch_name_with_equals += "=";
+  for (size_t i = 1; i < num_args; ++i) {
+    const wchar_t* arg = args[i];
+    std::string arg_as_utf8 = base::UTF16ToUTF8(arg);
+    if (arg_as_utf8.compare(
+            0, switch_name_with_equals.size(), switch_name_with_equals) == 0) {
+      *value = arg_as_utf8.substr(switch_name_with_equals.size());
+      return true;
+    }
+  }
+
+  return false;
+}
+
+}  // namespace
+
+WinMultiprocess::WinMultiprocess() {
+}
+
+void WinMultiprocess::Run() {
+  std::string switch_value;
+  if (GetSwitch(kIsMultiprocessChild, &switch_value)) {
+    // If we're in the child, then set up the handles we inherited from the
+    // parent. These are inherited from the parent and so are open and have the
+    // same value as in the parent. The values are passed to the child on the
+    // command line.
+    std::string left, right;
+    ASSERT_TRUE(SplitString(switch_value, '|', &left, &right));
+    unsigned int c2p_write, p2c_read;
+    ASSERT_TRUE(StringToNumber(left, &c2p_write));
+    ASSERT_TRUE(StringToNumber(right, &p2c_read));
+    pipe_c2p_write_.reset(reinterpret_cast<HANDLE>(c2p_write));
+    pipe_p2c_read_.reset(reinterpret_cast<HANDLE>(p2c_read));
+
+    // Notify the parent that it's OK to proceed. We only need to wait to get to
+    // the process entry point, but this is the easiest place we can notify.
+    char c = ' ';
+    CheckedWriteFile(WritePipeHandle(), &c, sizeof(c));
+
+    // Invoke the child side of the test.
+    WinMultiprocessChild();
+    exit(0);

[Robert Sesek, 2015/05/26 15:48:13]

Is it safe to use exit() and call exit-time-destructors, or should you call the
equivalent of _exit() ?

[scottmg, 2015/05/26 18:44:28]

This will be a completely separate unrelated process on Windows, so I think it
makes sense to exit normally.

+  } else {
+    // If we're in the parent, make pipes for child-to-parent and
+    // parent-to-child communication. Mark them as inheritable via the
+    // SECURITY_ATTRIBUTES, but use SetHandleInformation to ensure that the
+    // parent sides are not inherited.
+    SECURITY_ATTRIBUTES security_attributes = {0};
+    security_attributes.nLength = sizeof(SECURITY_ATTRIBUTES);
+    security_attributes.bInheritHandle = true;
+
+    HANDLE c2p_read, c2p_write;
+    PCHECK(CreatePipe(&c2p_read, &c2p_write, &security_attributes, 0));
+    PCHECK(SetHandleInformation(c2p_read, HANDLE_FLAG_INHERIT, 0));
+    pipe_c2p_read_.reset(c2p_read);
+    pipe_c2p_write_.reset(c2p_write);
+
+    HANDLE p2c_read, p2c_write;
+    PCHECK(CreatePipe(&p2c_read, &p2c_write, &security_attributes, 0));
+    PCHECK(SetHandleInformation(p2c_write, HANDLE_FLAG_INHERIT, 0));
+    pipe_p2c_read_.reset(p2c_read);
+    pipe_p2c_write_.reset(p2c_write);
+
+    // Build a command line for the child process that tells it only to run the
+    // current test, and to pass down the values of the pipe handles.
+    const ::testing::TestInfo* const test_info =
+        ::testing::UnitTest::GetInstance()->current_test_info();
+    std::wstring command_line = Paths::Executable().value() + L" " +
+                                base::UTF8ToUTF16(base::StringPrintf(
+                                    "--gtest_filter=%s.%s %s=0x%x|0x%x",
+                                    test_info->test_case_name(),
+                                    test_info->name(),
+                                    kIsMultiprocessChild,
+                                    c2p_write,
+                                    p2c_read));
+    STARTUPINFO startup_info = {0};
+    startup_info.cb = sizeof(startup_info);
+    startup_info.hStdInput = GetStdHandle(STD_INPUT_HANDLE);
+    startup_info.hStdOutput = GetStdHandle(STD_OUTPUT_HANDLE);
+    startup_info.hStdError = GetStdHandle(STD_ERROR_HANDLE);
+    startup_info.dwFlags = STARTF_USESTDHANDLES;
+    PROCESS_INFORMATION process_info;
+    PCHECK(
+        CreateProcess(Paths::Executable().value().c_str(),
+                      &command_line[0],  // This cannot be constant, per MSDN.
+                      nullptr,
+                      nullptr,
+                      true,  // Inherit handles.
+                      0,
+                      nullptr,
+                      nullptr,
+                      &startup_info,
+                      &process_info));
+    child_handle_.reset(process_info.hProcess);
+    CloseHandle(process_info.hThread);
+
+    // Block until the child process has launched. CreateProcess() returns
+    // immediately, and test code expects process initialization to have
+    // completed so it can, for example, use the process handle.
+    char c;
+    CheckedReadFile(pipe_c2p_read_.get(), &c, sizeof(c));
+    ASSERT_EQ(' ', c);
+
+    // These have been passed to the child, close our side.
+    pipe_c2p_write_.reset();
+    pipe_p2c_read_.reset();
+
+    WinMultiprocessParent();
+  }

[Robert Sesek, 2015/05/26 15:48:13]

In the POSIX version, Multiprocess then waits for the child to exit and it
collects the status code.

[scottmg, 2015/05/26 18:44:29]

Done, and added expectation+test for non-zero exit code.

+}
+
+WinMultiprocess::~WinMultiprocess() {
+}
+
+FileHandle WinMultiprocess::ReadPipeHandle() const {
+  FileHandle handle =
+      child_handle_.get() ? pipe_c2p_read_.get() : pipe_p2c_read_.get();
+  CHECK(handle != nullptr);
+  return handle;
+}
+
+FileHandle WinMultiprocess::WritePipeHandle() const {
+  FileHandle handle =
+      child_handle_.get() ? pipe_p2c_write_.get() : pipe_c2p_write_.get();
+  CHECK(handle != nullptr);
+  return handle;
+}
+
+void WinMultiprocess::CloseReadPipe() {
+  if (child_handle_.get())
+    pipe_c2p_read_.reset();
+  else
+    pipe_p2c_read_.reset();
+}
+
+void WinMultiprocess::CloseWritePipe() {
+  if (child_handle_.get())
+    pipe_p2c_write_.reset();
+  else
+    pipe_c2p_write_.reset();
+}
+
+HANDLE WinMultiprocess::ChildProcess() const {
+  EXPECT_NE(nullptr, child_handle_.get());
+  return child_handle_.get();
+}
+
+}  // namespace test
+}  // namespace crashpad