From 361c8fbbc15e74730908e28660cb742eba046a83 Mon Sep 17 00:00:00 2001
From: "jgm@google.com" <jgm@google.com@861a406c-534a-0410-8894-cb66d6ee9925>
Date: Mon, 2 Apr 2012 17:41:03 +0000
Subject: Added support for platforms where pthread_t is a struct rather than
 an integral type.

git-svn-id: http://googletest.googlecode.com/svn/trunk@613 861a406c-534a-0410-8894-cb66d6ee9925
---
 cmake/internal_utils.cmake          |  3 ++-
 include/gtest/internal/gtest-port.h | 28 +++++++++++++++++++++-------
 2 files changed, 23 insertions(+), 8 deletions(-)

diff --git a/cmake/internal_utils.cmake b/cmake/internal_utils.cmake
index 0561db4..8cb2189 100644
--- a/cmake/internal_utils.cmake
+++ b/cmake/internal_utils.cmake
@@ -79,7 +79,8 @@ macro(config_compiler_and_linker)
     # whether RTTI is enabled.  Therefore we define GTEST_HAS_RTTI
     # explicitly.
     set(cxx_no_rtti_flags "-fno-rtti -DGTEST_HAS_RTTI=0")
-    set(cxx_strict_flags "-Wextra")
+    set(cxx_strict_flags
+      "-Wextra -Wno-unused-parameter -Wno-missing-field-initializers")
   elseif (CMAKE_CXX_COMPILER_ID STREQUAL "SunPro")
     set(cxx_exception_flags "-features=except")
     # Sun Pro doesn't provide macros to indicate whether exceptions and
diff --git a/include/gtest/internal/gtest-port.h b/include/gtest/internal/gtest-port.h
index 8c96f31..66c5096 100644
--- a/include/gtest/internal/gtest-port.h
+++ b/include/gtest/internal/gtest-port.h
@@ -1240,21 +1240,23 @@ class MutexBase {
   void Lock() {
     GTEST_CHECK_POSIX_SUCCESS_(pthread_mutex_lock(&mutex_));
     owner_ = pthread_self();
+    has_owner_ = true;
   }
 
   // Releases this mutex.
   void Unlock() {
-    // We don't protect writing to owner_ here, as it's the caller's
-    // responsibility to ensure that the current thread holds the
+    // Since the lock is being released the owner_ field should no longer be
+    // considered valid. We don't protect writing to has_owner_ here, as it's
+    // the caller's responsibility to ensure that the current thread holds the
     // mutex when this is called.
-    owner_ = 0;
+    has_owner_ = false;
     GTEST_CHECK_POSIX_SUCCESS_(pthread_mutex_unlock(&mutex_));
   }
 
   // Does nothing if the current thread holds the mutex. Otherwise, crashes
   // with high probability.
   void AssertHeld() const {
-    GTEST_CHECK_(owner_ == pthread_self())
+    GTEST_CHECK_(has_owner_ && pthread_equal(owner_, pthread_self()))
         << "The current thread is not holding the mutex @" << this;
   }
 
@@ -1265,7 +1267,14 @@ class MutexBase {
   // have to be public.
  public:
   pthread_mutex_t mutex_;  // The underlying pthread mutex.
-  pthread_t owner_;  // The thread holding the mutex; 0 means no one holds it.
+  // has_owner_ indicates whether the owner_ field below contains a valid thread
+  // ID and is therefore safe to inspect (e.g., to use in pthread_equal()). All
+  // accesses to the owner_ field should be protected by a check of this field.
+  // An alternative might be to memset() owner_ to all zeros, but there's no
+  // guarantee that a zero'd pthread_t is necessarily invalid or even different
+  // from pthread_self().
+  bool has_owner_;
+  pthread_t owner_;  // The thread holding the mutex.
 };
 
 // Forward-declares a static mutex.
@@ -1273,8 +1282,13 @@ class MutexBase {
     extern ::testing::internal::MutexBase mutex
 
 // Defines and statically (i.e. at link time) initializes a static mutex.
+// The initialization list here does not explicitly initialize each field,
+// instead relying on default initialization for the unspecified fields. In
+// particular, the owner_ field (a pthread_t) is not explicitly initialized.
+// This allows initialization to work whether pthread_t is a scalar or struct.
+// The flag -Wmissing-field-initializers must not be specified for this to work.
 # define GTEST_DEFINE_STATIC_MUTEX_(mutex) \
-    ::testing::internal::MutexBase mutex = { PTHREAD_MUTEX_INITIALIZER, 0 }
+    ::testing::internal::MutexBase mutex = { PTHREAD_MUTEX_INITIALIZER, false }
 
 // The Mutex class can only be used for mutexes created at runtime. It
 // shares its API with MutexBase otherwise.
@@ -1282,7 +1296,7 @@ class Mutex : public MutexBase {
  public:
   Mutex() {
     GTEST_CHECK_POSIX_SUCCESS_(pthread_mutex_init(&mutex_, NULL));
-    owner_ = 0;
+    has_owner_ = false;
   }
   ~Mutex() {
     GTEST_CHECK_POSIX_SUCCESS_(pthread_mutex_destroy(&mutex_));
-- 
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