Improvements for MachMultiprocess

util/test/mac/mach_multiprocess_test.cc

 // Copyright 2014 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/test/mac/mach_multiprocess.h"
 
+#include <unistd.h>
+
 #include "base/basictypes.h"
 #include "gtest/gtest.h"
 #include "util/file/fd_io.h"
 #include "util/test/errors.h"
 
 namespace {
 
 using namespace crashpad;
 using namespace crashpad::test;
 
 class TestMachMultiprocess final : public MachMultiprocess {
  public:
   TestMachMultiprocess() : MachMultiprocess() {}
 
   ~TestMachMultiprocess() {}
 
  protected:
   // The base class will have already exercised the Mach ports for IPC and the
-  // child task port. Just make sure that the pipe is set up correctly.
+  // child task port. Just make sure that the pipe is set up correctly and that
+  // ChildPID() works as expected.
   virtual void Parent() override {
-    int fd = PipeFD();
-
+    int read_fd = ReadPipeFD();
     char c;
-    ssize_t rv = ReadFD(fd, &c, 1);
+    ssize_t rv = ReadFD(read_fd, &c, 1);
     ASSERT_EQ(1, rv) << ErrnoMessage("read");
     EXPECT_EQ('M', c);
 
+    pid_t pid;
+    rv = ReadFD(read_fd, &pid, sizeof(pid));
+    ASSERT_EQ(static_cast<ssize_t>(sizeof(pid)), rv) << ErrnoMessage("read");
+    EXPECT_EQ(pid, ChildPID());
+
+    int write_fd = WritePipeFD();
+    c = 'm';
+    rv = WriteFD(write_fd, &c, 1);
+    ASSERT_EQ(1, rv) << ErrnoMessage("write");
+
     // The child will close its end of the pipe and exit. Make sure that the
     // parent sees EOF.
-    rv = ReadFD(fd, &c, 1);
+    rv = ReadFD(read_fd, &c, 1);
     ASSERT_EQ(0, rv) << ErrnoMessage("read");
   }
 
   virtual void Child() override {
-    int fd = PipeFD();
+    int write_fd = WritePipeFD();
 
     char c = 'M';
-    ssize_t rv = WriteFD(fd, &c, 1);
+    ssize_t rv = WriteFD(write_fd, &c, 1);
     ASSERT_EQ(1, rv) << ErrnoMessage("write");
+
+    pid_t pid = getpid();
+    rv = WriteFD(write_fd, &pid, sizeof(pid));
+    ASSERT_EQ(static_cast<ssize_t>(sizeof(pid)), rv) << ErrnoMessage("write");
+
+    int read_fd = ReadPipeFD();
+    rv = ReadFD(read_fd, &c, 1);
+    ASSERT_EQ(1, rv) << ErrnoMessage("read");
+    EXPECT_EQ('m', c);
   }
 
  private:
   DISALLOW_COPY_AND_ASSIGN(TestMachMultiprocess);
 };
 
 TEST(MachMultiprocess, MachMultiprocess) {
   TestMachMultiprocess mach_multiprocess;
   mach_multiprocess.Run();
 }
 
 }  // namespace