Utility functions to interact with the NT loader's data structures and associ...

chrome_frame/crash_reporting/nt_loader_unittest.cc

+// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+#include "chrome_frame/crash_reporting/nt_loader.h"
+
+#include <tlhelp32.h>
+#include <winnt.h>
+#include <base/at_exit.h>
+#include <base/scoped_handle.h>
+#include <base/sys_info.h>
+#include <base/thread.h>
+#include "chrome_frame/crash_reporting/crash_dll.h"
+#include "gtest/gtest.h"
+
+namespace {
+void AssertIsCriticalSection(CRITICAL_SECTION* critsec) {
+  // Assert on some of the internals of the debug info if it has one.
+  RTL_CRITICAL_SECTION_DEBUG* debug = critsec->DebugInfo;
+  if (debug) {
+    ASSERT_EQ(RTL_CRITSECT_TYPE, debug->Type);
+    ASSERT_EQ(critsec, debug->CriticalSection);
+  }
+
+  // TODO(siggi): assert on the semaphore handle & object type?
+}
+
+class ScopedEnterCriticalSection {
+ public:
+  ScopedEnterCriticalSection(CRITICAL_SECTION* critsec) : critsec_(critsec) {
+    ::EnterCriticalSection(critsec_);
+  }
+
+  ~ScopedEnterCriticalSection() {
+    ::LeaveCriticalSection(critsec_);
+  }
+
+ private:
+  CRITICAL_SECTION* critsec_;
+};
+
+std::wstring FromUnicodeString(const UNICODE_STRING& str) {
+  return std::wstring(str.Buffer, str.Length / sizeof(str.Buffer[0]));
+}
+
+}  // namespace
+
+using namespace nt_loader;
+
+TEST(NtLoader, OwnsCriticalSection) {
+  // Use of Thread requires an atexit manager.
+  base::AtExitManager at_exit;
+
+  CRITICAL_SECTION cs = {};
+  ::InitializeCriticalSection(&cs);
+  EXPECT_FALSE(OwnsCriticalSection(&cs));
+
+  // Enter the critsec and assert we own it.
+  {
+    ScopedEnterCriticalSection lock1(&cs);
+
+    EXPECT_TRUE(OwnsCriticalSection(&cs));
+
+    // Re-enter the critsec and assert we own it.
+    ScopedEnterCriticalSection lock2(&cs);
+
+    EXPECT_TRUE(OwnsCriticalSection(&cs));
+  }
+
+  // Should no longer own it.
+  EXPECT_FALSE(OwnsCriticalSection(&cs));

[robertshield, 2010/03/11 18:30:38]

I believe this should be an ASSERT_FALSE. Reason being, that if we did still own
it, then the other thread would block on the EnterCriticalSection and then we'd
deadlock waiting for the Event to be set.

[Sigurður Ásgeirsson, 2010/03/11 18:40:21]

Well, the ownership of the CS is not in question here, that's quite well-defined
so it doesn't really matter whether I assert or expect, except for the little
detail that the CS will be orphaned on early exit.
What is in question here is the functionality of the OwnsCriticalSection
function, which is being tested against a well defined set of states on a CS
under test control.

+
+  // Make another thread grab it.
+  base::Thread other("Other threads");
+  ASSERT_TRUE(other.Start());
+  other.message_loop()->PostTask(
+      FROM_HERE, NewRunnableFunction(::EnterCriticalSection, &cs));
+
+  ScopedHandle event(::CreateEvent(NULL, FALSE, FALSE, NULL));
+  other.message_loop()->PostTask(
+      FROM_HERE, NewRunnableFunction(::SetEvent, event.Get()));
+
+  ASSERT_EQ(WAIT_OBJECT_0, ::WaitForSingleObject(event.Get(), INFINITE));
+
+  // We still shouldn't own it - the other thread does.
+  EXPECT_FALSE(OwnsCriticalSection(&cs));
+  // And we shouldn't be able to enter it.
+  EXPECT_EQ(0, ::TryEnterCriticalSection(&cs));

[robertshield, 2010/03/11 18:30:38]

ASSERT here too? should we Leave it if this succeeds or does that not matter
terribly much?

[Sigurður Ásgeirsson, 2010/03/11 18:40:21]

Yeah, same deal, this is more to verify that I didn't screw up on the
posttasks...

+
+  // Make the other thread release it.
+  other.message_loop()->PostTask(
+      FROM_HERE, NewRunnableFunction(::LeaveCriticalSection, &cs));
+
+  other.Stop();
+
+  ::DeleteCriticalSection(&cs);
+}
+
+TEST(NtLoader, GetLoaderLock) {
+  CRITICAL_SECTION* loader_lock = GetLoaderLock();
+
+  AssertIsCriticalSection(loader_lock);
+
+  // We should be able to enter and leave the loader's lock without trouble.
+  EnterCriticalSection(loader_lock);
+  LeaveCriticalSection(loader_lock);
+}
+
+TEST(NtLoader, OwnsLoaderLock) {
+  CRITICAL_SECTION* loader_lock = GetLoaderLock();
+
+  EXPECT_FALSE(OwnsLoaderLock());
+  EnterCriticalSection(loader_lock);
+  EXPECT_TRUE(OwnsLoaderLock());
+  LeaveCriticalSection(loader_lock);
+  EXPECT_FALSE(OwnsLoaderLock());
+}
+
+TEST(NtLoader, GetLoaderEntry) {
+  ScopedEnterCriticalSection lock(GetLoaderLock());
+
+  // Get all modules in the current process.
+  ScopedHandle snap(::CreateToolhelp32Snapshot(TH32CS_SNAPMODULE,
+                                               ::GetCurrentProcessId()));
+  EXPECT_TRUE(snap.Get() != NULL);
+
+  // Walk them, while checking we get an entry for each, and that it
+  // contains sane information.
+  MODULEENTRY32 module = { sizeof(module) };
+  ASSERT_TRUE(::Module32First(snap.Get(), &module));
+  do {
+    nt_loader::LDR_DATA_TABLE_ENTRY* entry =
+        nt_loader::GetLoaderEntry(module.hModule);
+    ASSERT_TRUE(entry != NULL);
+    ASSERT_EQ(module.hModule, reinterpret_cast<HMODULE>(entry->DllBase));
+    ASSERT_STREQ(module.szModule,
+                 FromUnicodeString(entry->BaseDllName).c_str());
+    ASSERT_STREQ(module.szExePath,
+                 FromUnicodeString(entry->FullDllName).c_str());
+  } while(::Module32Next(snap.Get(), &module));
+}
+
+namespace {
+
+typedef void (*ExceptionFunction)(EXCEPTION_POINTERS* ex_ptrs);
+
+class NtLoaderTest: public testing::Test {
+ public:
+  NtLoaderTest() : veh_id_(NULL), exception_function_(NULL) {
+    EXPECT_EQ(NULL, current_);
+    current_ = this;
+  }
+
+  ~NtLoaderTest() {
+    EXPECT_TRUE(this == current_);
+    current_ = NULL;
+  }
+
+  void SetUp() {
+    veh_id_ = ::AddVectoredExceptionHandler(FALSE, &ExceptionHandler);
+    EXPECT_TRUE(veh_id_ != NULL);
+
+    // Clear the crash DLL environment.
+    ::SetEnvironmentVariable(kCrashOnLoadMode, NULL);
+    ::SetEnvironmentVariable(kCrashOnUnloadMode, NULL);
+  }
+
+  void TearDown() {
+    if (veh_id_ != NULL)
+      EXPECT_NE(0, ::RemoveVectoredExceptionHandler(veh_id_));
+
+    // Clear the crash DLL environment.
+    ::SetEnvironmentVariable(kCrashOnLoadMode, NULL);
+    ::SetEnvironmentVariable(kCrashOnUnloadMode, NULL);
+  }
+
+  void set_exception_function(ExceptionFunction func) {
+    exception_function_ = func;
+  }
+
+ private:
+  static LONG NTAPI ExceptionHandler(EXCEPTION_POINTERS* ex_ptrs){
+    // Dispatch the exception to any exception function,
+    // but only on the main thread.
+    if (main_thread_ == ::GetCurrentThreadId() &&
+        current_ != NULL &&
+        current_->exception_function_ != NULL)
+      current_->exception_function_(ex_ptrs);
+
+    return ExceptionContinueSearch;
+  }
+
+  void* veh_id_;
+  ExceptionFunction exception_function_;
+
+  static NtLoaderTest* current_;
+  static DWORD main_thread_;
+};
+
+NtLoaderTest* NtLoaderTest::current_ = NULL;
+DWORD NtLoaderTest::main_thread_ = ::GetCurrentThreadId();
+
+const wchar_t kCrashDllName[] = L"crash_dll.dll";
+
+}  // namespace
+
+static int exceptions_handled = 0;
+static void OnCrashDuringLoadLibrary(EXCEPTION_POINTERS* ex_ptrs) {
+  ASSERT_EQ(STATUS_ACCESS_VIOLATION, ex_ptrs->ExceptionRecord->ExceptionCode);
+  ASSERT_EQ(2, ex_ptrs->ExceptionRecord->NumberParameters);
+  ASSERT_EQ(EXCEPTION_WRITE_FAULT,
+            ex_ptrs->ExceptionRecord->ExceptionInformation[0]);
+  ASSERT_EQ(kCrashAddress,
+            ex_ptrs->ExceptionRecord->ExceptionInformation[1]);
+
+  // Bump the exceptions count.
+  exceptions_handled++;
+
+  EXPECT_TRUE(OwnsLoaderLock());
+
+  HMODULE crash_dll = ::GetModuleHandle(kCrashDllName);
+  ASSERT_TRUE(crash_dll != NULL);
+
+  nt_loader::LDR_DATA_TABLE_ENTRY* entry = GetLoaderEntry(crash_dll);
+  ASSERT_TRUE(entry != NULL);
+  ASSERT_EQ(0, entry->Flags & LDRP_PROCESS_ATTACH_CALLED);
+}
+
+TEST_F(NtLoaderTest, CrashOnLoadLibrary) {
+  exceptions_handled = 0;
+  set_exception_function(OnCrashDuringLoadLibrary);
+
+  // Setup to crash on load.
+  ::SetEnvironmentVariable(kCrashOnLoadMode, L"1");
+
+  // And load it.
+  HMODULE module = ::LoadLibrary(kCrashDllName);
+  DWORD err = ::GetLastError();
+  EXPECT_EQ(NULL, module);
+  EXPECT_EQ(ERROR_NOACCESS, err);
+  EXPECT_EQ(1, exceptions_handled);
+
+  if (module != NULL)
+    ::FreeLibrary(module);
+}
+
+static void OnCrashDuringUnloadLibrary(EXCEPTION_POINTERS* ex_ptrs) {
+  ASSERT_EQ(STATUS_ACCESS_VIOLATION, ex_ptrs->ExceptionRecord->ExceptionCode);
+  ASSERT_EQ(2, ex_ptrs->ExceptionRecord->NumberParameters);
+  ASSERT_EQ(EXCEPTION_WRITE_FAULT,
+            ex_ptrs->ExceptionRecord->ExceptionInformation[0]);
+  ASSERT_EQ(kCrashAddress,
+            ex_ptrs->ExceptionRecord->ExceptionInformation[1]);
+
+  // Bump the exceptions count.
+  exceptions_handled++;
+
+  EXPECT_TRUE(OwnsLoaderLock());
+
+  HMODULE crash_dll = ::GetModuleHandle(kCrashDllName);
+  ASSERT_TRUE(crash_dll == NULL);
+
+  nt_loader::LDR_DATA_TABLE_ENTRY* entry = GetLoaderEntry(crash_dll);
+  ASSERT_TRUE(entry == NULL);
+}
+
+TEST_F(NtLoaderTest, CrashOnUnloadLibrary) {
+  // Setup to crash on unload.
+  ::SetEnvironmentVariable(kCrashOnUnloadMode, L"1");
+
+  // And load it.
+  HMODULE module = ::LoadLibrary(kCrashDllName);
+  EXPECT_TRUE(module != NULL);
+
+  exceptions_handled = 0;
+  set_exception_function(OnCrashDuringUnloadLibrary);
+
+  // We should crash during unload.
+  if (module != NULL)
+    ::FreeLibrary(module);
+
+  EXPECT_EQ(1, exceptions_handled);

[robertshield, 2010/03/11 18:30:38]

cool tests :)

[Sigurður Ásgeirsson, 2010/03/11 18:40:21]

Thanks, but the CRT bug is totally uncool, and it cost me a couple of hours to
work around it :(.

+}