Refactor multiprocess test code to allow multiple child processes to be launched.

test/win/win_child_process.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_child_process.h"
+
+#include <windows.h>
+#include <shellapi.h>
+
+#include <string>
+
+#include "base/logging.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(FATAL) << "CommandLineToArgvW";
+    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) {
+      if (value)
+        *value = arg_as_utf8.substr(switch_name_with_equals.size());
+      return true;
+    }
+  }
+
+  return false;
+}
+
+ScopedKernelHANDLE LaunchCommandLine(wchar_t* command_line) {
+  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;
+  if (!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)) {
+    PLOG(ERROR) << "CreateProcess";
+    return ScopedKernelHANDLE();
+  }
+  if (!CloseHandle(process_info.hThread)) {
+    PLOG(ERROR) << "CloseHandle";
+    if (!CloseHandle(process_info.hProcess))
+      PLOG(ERROR) << "CloseHandle";
+    return ScopedKernelHANDLE();
+  }
+  return ScopedKernelHANDLE(process_info.hProcess);
+}
+
+bool CreateInheritablePipe(ScopedFileHANDLE* read_handle,
+                           ScopedFileHANDLE* write_handle) {
+  SECURITY_ATTRIBUTES security_attributes = {0};
+  security_attributes.nLength = sizeof(SECURITY_ATTRIBUTES);
+  security_attributes.bInheritHandle = true;
+
+  HANDLE read, write;
+  BOOL result = CreatePipe(&read, &write, &security_attributes, 0);
+  if (!result) {
+    PLOG(ERROR) << "CreatePipe";
+    ADD_FAILURE() << "CreatePipe failed";
+    return false;
+  }
+  read_handle->reset(read);
+  write_handle->reset(write);
+  return true;
+}
+
+}  // namespace
+
+WinChildProcess::WinChildProcess() {
+  std::string switch_value;
+  CHECK(GetSwitch(kIsMultiprocessChild, &switch_value));
+
+  // 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;
+  CHECK(SplitString(switch_value, '|', &left, &right));
+  unsigned int write, read;
+  CHECK(StringToNumber(left, &write));
+  CHECK(StringToNumber(right, &read));
+  pipe_write_.reset(reinterpret_cast<HANDLE>(write));
+  pipe_read_.reset(reinterpret_cast<HANDLE>(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));
+}
+
+// static
+bool WinChildProcess::IsChildProcess() {
+  return GetSwitch(kIsMultiprocessChild, nullptr);
+}
+
+// static
+scoped_ptr<WinChildProcess::Handles> WinChildProcess::Launch() {
+  // 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.
+  scoped_ptr<Handles> handles_for_parent(new Handles);
+  ScopedFileHANDLE read_for_child;
+  ScopedFileHANDLE write_for_child;
+
+  if (!CreateInheritablePipe(&handles_for_parent->read, &write_for_child))
+    return scoped_ptr<Handles>();
+
+  if (!CreateInheritablePipe(&read_for_child, &handles_for_parent->write))
+    return scoped_ptr<Handles>();
+
+  if (!SetHandleInformation(

[scottmg, 2015/06/01 21:53:22]

Can you move this inside the helper function too? (And then move the explanatory
comment too)

[erikwright (departed), 2015/06/24 20:01:34]

Done.

+          handles_for_parent->read.get(), HANDLE_FLAG_INHERIT, 0)) {
+    PLOG(ERROR) << "SetHandleInformation";
+    ADD_FAILURE() << "SetHandleInformation";
+    return scoped_ptr<Handles>();
+  }
+  if (!SetHandleInformation(
+          handles_for_parent->write.get(), HANDLE_FLAG_INHERIT, 0)) {
+    PLOG(ERROR) << "SetHandleInformation";
+    ADD_FAILURE() << "SetHandleInformation";
+    return scoped_ptr<Handles>();
+  }
+
+  // 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,
+                                           write_for_child,
+                                           read_for_child.get()));
+
+  // Command-line buffer cannot be constant, per CreateProcess signature.
+  handles_for_parent->process = LaunchCommandLine(&command_line[0]);
+  if (!handles_for_parent->process.is_valid())
+    return scoped_ptr<Handles>();
+
+  // Block until the child process has launched. CreateProcess() returns
+  // immediately, and test code expects process initialization to have
+  // completed so it can, for example, read the process memory.
+  char c;
+  if (!LoggingReadFile(handles_for_parent->read.get(), &c, sizeof(c))) {
+    ADD_FAILURE() << "LoggedReadFile";
+    return scoped_ptr<Handles>();
+  }
+
+  if (c != ' ') {
+    ADD_FAILURE() << "invalid data read from child";
+    return scoped_ptr<Handles>();
+  }
+
+  return handles_for_parent.Pass();
+}
+
+FileHandle WinChildProcess::ReadPipeHandle() const {
+  return pipe_read_.get();
+}
+
+FileHandle WinChildProcess::WritePipeHandle() const {
+  return pipe_write_.get();
+}
+
+void WinChildProcess::CloseReadPipe() {
+  pipe_read_.reset();
+}
+
+void WinChildProcess::CloseWritePipe() {
+  pipe_write_.reset();
+}
+
+}  // namespace test
+}  // namespace crashpad