base/debug/stack_trace_unittest.cc

// Copyright 2011 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include <stddef.h>

#include <limits>
#include <sstream>
#include <string>

#include "base/debug/debugging_buildflags.h"
#include "base/debug/stack_trace.h"
#include "base/logging.h"
#include "base/process/kill.h"
#include "base/process/process_handle.h"
#include "base/profiler/stack_buffer.h"
#include "base/profiler/stack_copier.h"
#include "base/test/test_timeouts.h"
#include "build/build_config.h"
#include "testing/gtest/include/gtest/gtest.h"
#include "testing/multiprocess_func_list.h"

#if BUILDFLAG(IS_POSIX) && !BUILDFLAG(IS_ANDROID) && !BUILDFLAG(IS_IOS)
#include "base/test/multiprocess_test.h"
#endif

namespace base {
namespace debug {

#if BUILDFLAG(IS_POSIX) && !BUILDFLAG(IS_ANDROID) && !BUILDFLAG(IS_IOS)
typedef MultiProcessTest StackTraceTest;
#else
typedef testing::Test StackTraceTest;
#endif

#if !defined(__UCLIBC__) && !defined(_AIX) && !defined(COMPILER_MSVC)
// StackTrace::OutputToStream() is not implemented under uclibc, nor AIX.
// See https://crbug.com/706728

TEST_F(StackTraceTest, OutputToStream) {
  StackTrace trace;

  // Dump the trace into a string.
  std::ostringstream os;
  trace.OutputToStream(&os);
  std::string backtrace_message = os.str();

  // ToString() should produce the same output.
  EXPECT_EQ(backtrace_message, trace.ToString());

  size_t frames_found = 0;
  const void* const* addresses = trace.Addresses(&frames_found);

#if defined(OFFICIAL_BUILD) && \
    ((BUILDFLAG(IS_POSIX) && !BUILDFLAG(IS_APPLE)) || BUILDFLAG(IS_FUCHSIA))
  // Stack traces require an extra data table that bloats our binaries,
  // so they're turned off for official builds. Stop the test here, so
  // it at least verifies that StackTrace calls don't crash.
  return;
#endif  // defined(OFFICIAL_BUILD) &&
        // ((BUILDFLAG(IS_POSIX) && !BUILDFLAG(IS_APPLE)) ||
        // BUILDFLAG(IS_FUCHSIA))

  ASSERT_TRUE(addresses);
  ASSERT_GT(frames_found, 5u) << "Too few frames found.";

  if (!StackTrace::WillSymbolizeToStreamForTesting())
    return;

  // Check if the output has symbol initialization warning.  If it does, fail.
  ASSERT_EQ(backtrace_message.find("Dumping unresolved backtrace"),
            std::string::npos)
      << "Unable to resolve symbols.";

  // Expect a demangled symbol.
  // Note that Windows Release builds omit the function parameters from the
  // demangled stack output, otherwise this could be "testing::UnitTest::Run()".
  EXPECT_TRUE(backtrace_message.find("testing::UnitTest::Run") !=
              std::string::npos)
      << "Expected a demangled symbol in backtrace:\n"
      << backtrace_message;

  // Expect to at least find main.
  EXPECT_TRUE(backtrace_message.find("main") != std::string::npos)
      << "Expected to find main in backtrace:\n"
      << backtrace_message;

  // Expect to find this function as well.
  // Note: This will fail if not linked with -rdynamic (aka -export_dynamic)
  EXPECT_TRUE(backtrace_message.find(__func__) != std::string::npos)
      << "Expected to find " << __func__ << " in backtrace:\n"
      << backtrace_message;
}

#if !defined(OFFICIAL_BUILD) && !defined(NO_UNWIND_TABLES)
// Disabled in Official builds, where Link-Time Optimization can result in two
// or fewer stack frames being available, causing the test to fail.
TEST_F(StackTraceTest, TruncatedTrace) {
  StackTrace trace;

  size_t count = 0;
  trace.Addresses(&count);
  ASSERT_LT(2u, count);

  StackTrace truncated(2);
  truncated.Addresses(&count);
  EXPECT_EQ(2u, count);
}
#endif  // !defined(OFFICIAL_BUILD) && !defined(NO_UNWIND_TABLES)

// The test is used for manual testing, e.g., to see the raw output.
TEST_F(StackTraceTest, DebugOutputToStream) {
  StackTrace trace;
  std::ostringstream os;
  trace.OutputToStream(&os);
  VLOG(1) << os.str();
}

// The test is used for manual testing, e.g., to see the raw output.
TEST_F(StackTraceTest, DebugPrintBacktrace) {
  StackTrace().Print();
}

// The test is used for manual testing, e.g., to see the raw output.
TEST_F(StackTraceTest, DebugPrintWithPrefixBacktrace) {
  StackTrace().PrintWithPrefix("[test]");
}

// Make sure nullptr prefix doesn't crash. Output not examined, much
// like the DebugPrintBacktrace test above.
TEST_F(StackTraceTest, DebugPrintWithNullPrefixBacktrace) {
  StackTrace().PrintWithPrefix(nullptr);
}

// Test OutputToStreamWithPrefix, mainly to make sure it doesn't
// crash. Any "real" stack trace testing happens above.
TEST_F(StackTraceTest, DebugOutputToStreamWithPrefix) {
  StackTrace trace;
  const char* prefix_string = "[test]";
  std::ostringstream os;
  trace.OutputToStreamWithPrefix(&os, prefix_string);
  std::string backtrace_message = os.str();

  // ToStringWithPrefix() should produce the same output.
  EXPECT_EQ(backtrace_message, trace.ToStringWithPrefix(prefix_string));
}

// Make sure nullptr prefix doesn't crash. Output not examined, much
// like the DebugPrintBacktrace test above.
TEST_F(StackTraceTest, DebugOutputToStreamWithNullPrefix) {
  StackTrace trace;
  std::ostringstream os;
  trace.OutputToStreamWithPrefix(&os, nullptr);
  trace.ToStringWithPrefix(nullptr);
}

#endif  // !defined(__UCLIBC__) && !defined(_AIX)

#if BUILDFLAG(IS_POSIX) && !BUILDFLAG(IS_ANDROID)
// Starboard does not support relative file paths, needed by |SpawnChild()|.
#if !BUILDFLAG(IS_IOS) && !defined(STARBOARD)
static char* newArray() {
  // Clang warns about the mismatched new[]/delete if they occur in the same
  // function.
  return new char[10];
}

MULTIPROCESS_TEST_MAIN(MismatchedMallocChildProcess) {
  char* pointer = newArray();
  delete pointer;
  return 2;
}

// Regression test for StackDumpingSignalHandler async-signal unsafety.
// Combined with tcmalloc's debugallocation, that signal handler
// and e.g. mismatched new[]/delete would cause a hang because
// of re-entering malloc.
TEST_F(StackTraceTest, AsyncSignalUnsafeSignalHandlerHang) {
  Process child = SpawnChild("MismatchedMallocChildProcess");
  ASSERT_TRUE(child.IsValid());
  int exit_code;
  ASSERT_TRUE(
      child.WaitForExitWithTimeout(TestTimeouts::action_timeout(), &exit_code));
}
#endif  // !BUILDFLAG(IS_IOS)

namespace {

std::string itoa_r_wrapper(intptr_t i, size_t sz, int base, size_t padding) {
  char buffer[1024];
  CHECK_LE(sz, sizeof(buffer));

  char* result = internal::itoa_r(i, buffer, sz, base, padding);
  EXPECT_TRUE(result);
  return std::string(buffer);
}

}  // namespace

TEST_F(StackTraceTest, itoa_r) {
  EXPECT_EQ("0", itoa_r_wrapper(0, 128, 10, 0));
  EXPECT_EQ("-1", itoa_r_wrapper(-1, 128, 10, 0));

  // Test edge cases.
  if (sizeof(intptr_t) == 4) {
    EXPECT_EQ("ffffffff", itoa_r_wrapper(-1, 128, 16, 0));
    EXPECT_EQ("-2147483648",
              itoa_r_wrapper(std::numeric_limits<intptr_t>::min(), 128, 10, 0));
    EXPECT_EQ("2147483647",
              itoa_r_wrapper(std::numeric_limits<intptr_t>::max(), 128, 10, 0));

    EXPECT_EQ("80000000",
              itoa_r_wrapper(std::numeric_limits<intptr_t>::min(), 128, 16, 0));
    EXPECT_EQ("7fffffff",
              itoa_r_wrapper(std::numeric_limits<intptr_t>::max(), 128, 16, 0));
  } else if (sizeof(intptr_t) == 8) {
    EXPECT_EQ("ffffffffffffffff", itoa_r_wrapper(-1, 128, 16, 0));
    EXPECT_EQ("-9223372036854775808",
              itoa_r_wrapper(std::numeric_limits<intptr_t>::min(), 128, 10, 0));
    EXPECT_EQ("9223372036854775807",
              itoa_r_wrapper(std::numeric_limits<intptr_t>::max(), 128, 10, 0));

    EXPECT_EQ("8000000000000000",
              itoa_r_wrapper(std::numeric_limits<intptr_t>::min(), 128, 16, 0));
    EXPECT_EQ("7fffffffffffffff",
              itoa_r_wrapper(std::numeric_limits<intptr_t>::max(), 128, 16, 0));
  } else {
    ADD_FAILURE() << "Missing test case for your size of intptr_t ("
                  << sizeof(intptr_t) << ")";
  }

  // Test hex output.
  EXPECT_EQ("688", itoa_r_wrapper(0x688, 128, 16, 0));
  EXPECT_EQ("deadbeef", itoa_r_wrapper(0xdeadbeef, 128, 16, 0));

  // Check that itoa_r respects passed buffer size limit.
  char buffer[1024];
  EXPECT_TRUE(internal::itoa_r(0xdeadbeef, buffer, 10, 16, 0));
  EXPECT_TRUE(internal::itoa_r(0xdeadbeef, buffer, 9, 16, 0));
  EXPECT_FALSE(internal::itoa_r(0xdeadbeef, buffer, 8, 16, 0));
  EXPECT_FALSE(internal::itoa_r(0xdeadbeef, buffer, 7, 16, 0));
  EXPECT_TRUE(internal::itoa_r(0xbeef, buffer, 5, 16, 4));
  EXPECT_FALSE(internal::itoa_r(0xbeef, buffer, 5, 16, 5));
  EXPECT_FALSE(internal::itoa_r(0xbeef, buffer, 5, 16, 6));

  // Test padding.
  EXPECT_EQ("1", itoa_r_wrapper(1, 128, 10, 0));
  EXPECT_EQ("1", itoa_r_wrapper(1, 128, 10, 1));
  EXPECT_EQ("01", itoa_r_wrapper(1, 128, 10, 2));
  EXPECT_EQ("001", itoa_r_wrapper(1, 128, 10, 3));
  EXPECT_EQ("0001", itoa_r_wrapper(1, 128, 10, 4));
  EXPECT_EQ("00001", itoa_r_wrapper(1, 128, 10, 5));
  EXPECT_EQ("688", itoa_r_wrapper(0x688, 128, 16, 0));
  EXPECT_EQ("688", itoa_r_wrapper(0x688, 128, 16, 1));
  EXPECT_EQ("688", itoa_r_wrapper(0x688, 128, 16, 2));
  EXPECT_EQ("688", itoa_r_wrapper(0x688, 128, 16, 3));
  EXPECT_EQ("0688", itoa_r_wrapper(0x688, 128, 16, 4));
  EXPECT_EQ("00688", itoa_r_wrapper(0x688, 128, 16, 5));
}
#endif  // BUILDFLAG(IS_POSIX) && !BUILDFLAG(IS_ANDROID)

#if BUILDFLAG(CAN_UNWIND_WITH_FRAME_POINTERS)

class CopyFunction : public StackCopier {
 public:
  using StackCopier::CopyStackContentsAndRewritePointers;
};

// Copies the current stack segment, starting from the frame pointer of the
// caller frame. Also fills in |stack_end| for the copied stack.
NOINLINE static std::unique_ptr<StackBuffer> CopyCurrentStackAndRewritePointers(
    uintptr_t* out_fp,
    uintptr_t* stack_end) {
  const uint8_t* fp =
      reinterpret_cast<const uint8_t*>(__builtin_frame_address(0));
  uintptr_t original_stack_end = GetStackEnd();
  size_t stack_size = original_stack_end - reinterpret_cast<uintptr_t>(fp);
  auto buffer = std::make_unique<StackBuffer>(stack_size);
  *out_fp = reinterpret_cast<uintptr_t>(
      CopyFunction::CopyStackContentsAndRewritePointers(
          fp, reinterpret_cast<const uintptr_t*>(original_stack_end),
          StackBuffer::kPlatformStackAlignment, buffer->buffer()));
  *stack_end = *out_fp + stack_size;
  return buffer;
}

template <size_t Depth>
NOINLINE void ExpectStackFramePointers(const void** frames,
                                       size_t max_depth,
                                       bool copy_stack) {
code_start:
  // Calling __builtin_frame_address() forces compiler to emit
  // frame pointers, even if they are not enabled.
  EXPECT_NE(nullptr, __builtin_frame_address(0));
  ExpectStackFramePointers<Depth - 1>(frames, max_depth, copy_stack);

  constexpr size_t frame_index = Depth - 1;
  const void* frame = frames[frame_index];
  EXPECT_GE(frame, &&code_start) << "For frame at index " << frame_index;
  EXPECT_LE(frame, &&code_end) << "For frame at index " << frame_index;
code_end:
  return;
}

template <>
NOINLINE void ExpectStackFramePointers<1>(const void** frames,
                                          size_t max_depth,
                                          bool copy_stack) {
code_start:
  // Calling __builtin_frame_address() forces compiler to emit
  // frame pointers, even if they are not enabled.
  EXPECT_NE(nullptr, __builtin_frame_address(0));
  size_t count = 0;
  if (copy_stack) {
    uintptr_t stack_end = 0, fp = 0;
    std::unique_ptr<StackBuffer> copy =
        CopyCurrentStackAndRewritePointers(&fp, &stack_end);
    count =
        TraceStackFramePointersFromBuffer(fp, stack_end, frames, max_depth, 0);
  } else {
    count = TraceStackFramePointers(frames, max_depth, 0);
  }
  ASSERT_EQ(max_depth, count);

  const void* frame = frames[0];
  EXPECT_GE(frame, &&code_start) << "For the top frame";
  EXPECT_LE(frame, &&code_end) << "For the top frame";
code_end:
  return;
}

#if defined(MEMORY_SANITIZER)
// The test triggers use-of-uninitialized-value errors on MSan bots.
// This is expected because we're walking and reading the stack, and
// sometimes we read fp / pc from the place that previously held
// uninitialized value.
#define MAYBE_TraceStackFramePointers DISABLED_TraceStackFramePointers
#else
#define MAYBE_TraceStackFramePointers TraceStackFramePointers
#endif
TEST_F(StackTraceTest, MAYBE_TraceStackFramePointers) {
  constexpr size_t kDepth = 5;
  const void* frames[kDepth];
  ExpectStackFramePointers<kDepth>(frames, kDepth, /*copy_stack=*/false);
}

// The test triggers use-of-uninitialized-value errors on MSan bots.
// This is expected because we're walking and reading the stack, and
// sometimes we read fp / pc from the place that previously held
// uninitialized value.
// TODO(crbug.com/1132511): Enable this test on Fuchsia.
#if defined(MEMORY_SANITIZER) || BUILDFLAG(IS_FUCHSIA) || \
    defined(STARBOARD) && defined(ADDRESS_SANITIZER) || SB_IS(EVERGREEN)
#define MAYBE_TraceStackFramePointersFromBuffer \
  DISABLED_TraceStackFramePointersFromBuffer
#else
#define MAYBE_TraceStackFramePointersFromBuffer \
  TraceStackFramePointersFromBuffer
#endif
TEST_F(StackTraceTest, MAYBE_TraceStackFramePointersFromBuffer) {
  constexpr size_t kDepth = 5;
  const void* frames[kDepth];
  ExpectStackFramePointers<kDepth>(frames, kDepth, /*copy_stack=*/true);
}

#if BUILDFLAG(IS_ANDROID) || BUILDFLAG(IS_APPLE)
#define MAYBE_StackEnd StackEnd
#else
#define MAYBE_StackEnd DISABLED_StackEnd
#endif

TEST_F(StackTraceTest, MAYBE_StackEnd) {
  EXPECT_NE(0u, GetStackEnd());
}

#endif  // BUILDFLAG(CAN_UNWIND_WITH_FRAME_POINTERS)

#if BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_ANDROID)

#if !defined(ADDRESS_SANITIZER) && !defined(UNDEFINED_SANITIZER)

#if !defined(ARCH_CPU_ARM_FAMILY)
// On Arm architecture invalid math operations such as division by zero are not
// trapped and do not trigger a SIGFPE.
// Hence disable the test for Arm platforms.
TEST(CheckExitCodeAfterSignalHandlerDeathTest, CheckSIGFPE) {
  // Values are volatile to prevent reordering of instructions, i.e. for
  // optimization. Reordering may lead to tests erroneously failing due to
  // SIGFPE being raised outside of EXPECT_EXIT.
  volatile int const nominator = 23;
  volatile int const denominator = 0;
  [[maybe_unused]] volatile int result;

  EXPECT_EXIT(result = nominator / denominator,
              ::testing::KilledBySignal(SIGFPE), "");
}
#endif  // !defined(ARCH_CPU_ARM_FAMILY)

TEST(CheckExitCodeAfterSignalHandlerDeathTest, CheckSIGSEGV) {
  // Pointee and pointer are volatile to prevent reordering of instructions,
  // i.e. for optimization. Reordering may lead to tests erroneously failing due
  // to SIGSEGV being raised outside of EXPECT_EXIT.
  volatile int* const volatile p_int = nullptr;

  EXPECT_EXIT(*p_int = 1234, ::testing::KilledBySignal(SIGSEGV), "");
}

#if defined(ARCH_CPU_X86_64)
TEST(CheckExitCodeAfterSignalHandlerDeathTest,
     CheckSIGSEGVNonCanonicalAddress) {
  // Pointee and pointer are volatile to prevent reordering of instructions,
  // i.e. for optimization. Reordering may lead to tests erroneously failing due
  // to SIGSEGV being raised outside of EXPECT_EXIT.
  //
  // On Linux, the upper half of the address space is reserved by the kernel, so
  // all upper bits must be 0 for canonical addresses.
  volatile int* const volatile p_int =
      reinterpret_cast<int*>(0xabcdabcdabcdabcdULL);

  EXPECT_EXIT(*p_int = 1234, ::testing::KilledBySignal(SIGSEGV), "SI_KERNEL");
}
#endif

#endif  // #if !defined(ADDRESS_SANITIZER) && !defined(UNDEFINED_SANITIZER)

#if !defined(STARBOARD)
TEST(CheckExitCodeAfterSignalHandlerDeathTest, CheckSIGILL) {
  auto const raise_sigill = []() {
#if defined(ARCH_CPU_X86_FAMILY)
    asm("ud2");
#elif defined(ARCH_CPU_ARM_FAMILY)
    asm("udf 0");
#else
#error Unsupported platform!
#endif
  };

  EXPECT_EXIT(raise_sigill(), ::testing::KilledBySignal(SIGILL), "");
}
#endif  // !defined(STARBOARD)

#endif  // BUILDFLAG(IS_LINUX) || BUILDFLAG(IS_ANDROID)

}  // namespace debug
}  // namespace base