diff --git a/src/symbolize_unittest.cc b/src/symbolize_unittest.cc
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+++ b/src/symbolize_unittest.cc
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+// Copyright (c) 2006, Google Inc.
+// All rights reserved.
+//
+// Redistribution and use in source and binary forms, with or without
+// modification, are permitted provided that the following conditions are
+// met:
+//
+//     * Redistributions of source code must retain the above copyright
+// notice, this list of conditions and the following disclaimer.
+//     * Redistributions in binary form must reproduce the above
+// copyright notice, this list of conditions and the following disclaimer
+// in the documentation and/or other materials provided with the
+// distribution.
+//     * Neither the name of Google Inc. nor the names of its
+// contributors may be used to endorse or promote products derived from
+// this software without specific prior written permission.
+//
+// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
+// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
+// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
+// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+//
+// Author: Satoru Takabayashi
+//
+// Unit tests for functions in symbolize.cc.
+
+#include "utilities.h"
+
+#include <signal.h>
+#include <iostream>
+
+#include "glog/logging.h"
+#include "symbolize.h"
+#include "googletest.h"
+#include "config.h"
+
+#ifdef HAVE_LIB_GFLAGS
+#include <gflags/gflags.h>
+using namespace GFLAGS_NAMESPACE;
+#endif
+
+using namespace std;
+using namespace GOOGLE_NAMESPACE;
+
+#if defined(HAVE_STACKTRACE)
+
+#define always_inline
+
+// A wrapper function for Symbolize() to make the unit test simple.
+static const char *TrySymbolize(void *pc) {
+  static char symbol[4096];
+  if (Symbolize(pc, symbol, sizeof(symbol))) {
+    return symbol;
+  } else {
+    return NULL;
+  }
+}
+
+# if defined(__ELF__)
+
+// This unit tests make sense only with GCC.
+// Uses lots of GCC specific features.
+#if defined(__GNUC__) && !defined(__OPENCC__)
+#  if __GNUC__ >= 4
+#    define TEST_WITH_MODERN_GCC
+#    if __i386__  // always_inline isn't supported for x86_64 with GCC 4.1.0.
+#      undef always_inline
+#      define always_inline __attribute__((always_inline))
+#      define HAVE_ALWAYS_INLINE
+#    endif  // __i386__
+#  else
+#  endif  // __GNUC__ >= 4
+#  if defined(__i386__) || defined(__x86_64__)
+#    define TEST_X86_32_AND_64 1
+#  endif  // defined(__i386__) || defined(__x86_64__)
+#endif
+
+// Make them C linkage to avoid mangled names.
+extern "C" {
+void nonstatic_func();
+void nonstatic_func() {
+  volatile int a = 0;
+  ++a;
+}
+
+static void static_func() {
+  volatile int a = 0;
+  ++a;
+}
+}
+
+TEST(Symbolize, Symbolize) {
+  // We do C-style cast since GCC 2.95.3 doesn't allow
+  // reinterpret_cast<void *>(&func).
+
+  // Compilers should give us pointers to them.
+  EXPECT_STREQ("nonstatic_func", TrySymbolize((void *)(&nonstatic_func)));
+
+  // The name of an internal linkage symbol is not specified; allow either a
+  // mangled or an unmangled name here.
+  const char *static_func_symbol = TrySymbolize((void *)(&static_func));
+  CHECK(NULL != static_func_symbol);
+  EXPECT_TRUE(strcmp("static_func", static_func_symbol) == 0 ||
+              strcmp("static_func()", static_func_symbol) == 0);
+
+  EXPECT_TRUE(NULL == TrySymbolize(NULL));
+}
+
+struct Foo {
+  static void func(int x);
+};
+
+void ATTRIBUTE_NOINLINE Foo::func(int x) {
+  volatile int a = x;
+  ++a;
+}
+
+// With a modern GCC, Symbolize() should return demangled symbol
+// names.  Function parameters should be omitted.
+#ifdef TEST_WITH_MODERN_GCC
+TEST(Symbolize, SymbolizeWithDemangling) {
+  Foo::func(100);
+  EXPECT_STREQ("Foo::func()", TrySymbolize((void *)(&Foo::func)));
+}
+#endif
+
+// Tests that verify that Symbolize footprint is within some limit.
+
+// To measure the stack footprint of the Symbolize function, we create
+// a signal handler (for SIGUSR1 say) that calls the Symbolize function
+// on an alternate stack. This alternate stack is initialized to some
+// known pattern (0x55, 0x55, 0x55, ...). We then self-send this signal,
+// and after the signal handler returns, look at the alternate stack
+// buffer to see what portion has been touched.
+//
+// This trick gives us the the stack footprint of the signal handler.
+// But the signal handler, even before the call to Symbolize, consumes
+// some stack already. We however only want the stack usage of the
+// Symbolize function. To measure this accurately, we install two signal
+// handlers: one that does nothing and just returns, and another that
+// calls Symbolize. The difference between the stack consumption of these
+// two signals handlers should give us the Symbolize stack foorprint.
+
+static void *g_pc_to_symbolize;
+static char g_symbolize_buffer[4096];
+static char *g_symbolize_result;
+
+static void EmptySignalHandler(int signo) {}
+
+static void SymbolizeSignalHandler(int signo) {
+  if (Symbolize(g_pc_to_symbolize, g_symbolize_buffer,
+                sizeof(g_symbolize_buffer))) {
+    g_symbolize_result = g_symbolize_buffer;
+  } else {
+    g_symbolize_result = NULL;
+  }
+}
+
+const int kAlternateStackSize = 8096;
+const char kAlternateStackFillValue = 0x55;
+
+// These helper functions look at the alternate stack buffer, and figure
+// out what portion of this buffer has been touched - this is the stack
+// consumption of the signal handler running on this alternate stack.
+static ATTRIBUTE_NOINLINE bool StackGrowsDown(int *x) {
+  int y;
+  return &y < x;
+}
+static int GetStackConsumption(const char* alt_stack) {
+  int x;
+  if (StackGrowsDown(&x)) {
+    for (int i = 0; i < kAlternateStackSize; i++) {
+      if (alt_stack[i] != kAlternateStackFillValue) {
+        return (kAlternateStackSize - i);
+      }
+    }
+  } else {
+    for (int i = (kAlternateStackSize - 1); i >= 0; i--) {
+      if (alt_stack[i] != kAlternateStackFillValue) {
+        return i;
+      }
+    }
+  }
+  return -1;
+}
+
+#ifdef HAVE_SIGALTSTACK
+
+// Call Symbolize and figure out the stack footprint of this call.
+static const char *SymbolizeStackConsumption(void *pc, int *stack_consumed) {
+
+  g_pc_to_symbolize = pc;
+
+  // The alt-signal-stack cannot be heap allocated because there is a
+  // bug in glibc-2.2 where some signal handler setup code looks at the
+  // current stack pointer to figure out what thread is currently running.
+  // Therefore, the alternate stack must be allocated from the main stack
+  // itself.
+  char altstack[kAlternateStackSize];
+  memset(altstack, kAlternateStackFillValue, kAlternateStackSize);
+
+  // Set up the alt-signal-stack (and save the older one).
+  stack_t sigstk;
+  memset(&sigstk, 0, sizeof(stack_t));
+  stack_t old_sigstk;
+  sigstk.ss_sp = altstack;
+  sigstk.ss_size = kAlternateStackSize;
+  sigstk.ss_flags = 0;
+  CHECK_ERR(sigaltstack(&sigstk, &old_sigstk));
+
+  // Set up SIGUSR1 and SIGUSR2 signal handlers (and save the older ones).
+  struct sigaction sa;
+  memset(&sa, 0, sizeof(struct sigaction));
+  struct sigaction old_sa1, old_sa2;
+  sigemptyset(&sa.sa_mask);
+  sa.sa_flags = SA_ONSTACK;
+
+  // SIGUSR1 maps to EmptySignalHandler.
+  sa.sa_handler = EmptySignalHandler;
+  CHECK_ERR(sigaction(SIGUSR1, &sa, &old_sa1));
+
+  // SIGUSR2 maps to SymbolizeSignalHanlder.
+  sa.sa_handler = SymbolizeSignalHandler;
+  CHECK_ERR(sigaction(SIGUSR2, &sa, &old_sa2));
+
+  // Send SIGUSR1 signal and measure the stack consumption of the empty
+  // signal handler.
+  CHECK_ERR(kill(getpid(), SIGUSR1));
+  int stack_consumption1 = GetStackConsumption(altstack);
+
+  // Send SIGUSR2 signal and measure the stack consumption of the symbolize
+  // signal handler.
+  CHECK_ERR(kill(getpid(), SIGUSR2));
+  int stack_consumption2 = GetStackConsumption(altstack);
+
+  // The difference between the two stack consumption values is the
+  // stack footprint of the Symbolize function.
+  if (stack_consumption1 != -1 && stack_consumption2 != -1) {
+    *stack_consumed = stack_consumption2 - stack_consumption1;
+  } else {
+    *stack_consumed = -1;
+  }
+
+  // Log the stack consumption values.
+  LOG(INFO) << "Stack consumption of empty signal handler: "
+            << stack_consumption1;
+  LOG(INFO) << "Stack consumption of symbolize signal handler: "
+            << stack_consumption2;
+  LOG(INFO) << "Stack consumption of Symbolize: " << *stack_consumed;
+
+  // Now restore the old alt-signal-stack and signal handlers.
+  CHECK_ERR(sigaltstack(&old_sigstk, NULL));
+  CHECK_ERR(sigaction(SIGUSR1, &old_sa1, NULL));
+  CHECK_ERR(sigaction(SIGUSR2, &old_sa2, NULL));
+
+  return g_symbolize_result;
+}
+
+#ifdef __ppc64__
+// Symbolize stack consumption should be within 4kB.
+const int kStackConsumptionUpperLimit = 4096;
+#else
+// Symbolize stack consumption should be within 2kB.
+const int kStackConsumptionUpperLimit = 2048;
+#endif
+
+TEST(Symbolize, SymbolizeStackConsumption) {
+  int stack_consumed;
+  const char* symbol;
+
+  symbol = SymbolizeStackConsumption((void *)(&nonstatic_func),
+                                     &stack_consumed);
+  EXPECT_STREQ("nonstatic_func", symbol);
+  EXPECT_GT(stack_consumed, 0);
+  EXPECT_LT(stack_consumed, kStackConsumptionUpperLimit);
+
+  // The name of an internal linkage symbol is not specified; allow either a
+  // mangled or an unmangled name here.
+  symbol = SymbolizeStackConsumption((void *)(&static_func),
+                                     &stack_consumed);
+  CHECK(NULL != symbol);
+  EXPECT_TRUE(strcmp("static_func", symbol) == 0 ||
+              strcmp("static_func()", symbol) == 0);
+  EXPECT_GT(stack_consumed, 0);
+  EXPECT_LT(stack_consumed, kStackConsumptionUpperLimit);
+}
+
+#ifdef TEST_WITH_MODERN_GCC
+TEST(Symbolize, SymbolizeWithDemanglingStackConsumption) {
+  Foo::func(100);
+  int stack_consumed;
+  const char* symbol;
+
+  symbol = SymbolizeStackConsumption((void *)(&Foo::func), &stack_consumed);
+
+  EXPECT_STREQ("Foo::func()", symbol);
+  EXPECT_GT(stack_consumed, 0);
+  EXPECT_LT(stack_consumed, kStackConsumptionUpperLimit);
+}
+#endif
+
+#endif  // HAVE_SIGALTSTACK
+
+// x86 specific tests.  Uses some inline assembler.
+extern "C" {
+inline void* always_inline inline_func() {
+  void *pc = NULL;
+#ifdef TEST_X86_32_AND_64
+  __asm__ __volatile__("call 1f; 1: pop %0" : "=r"(pc));
+#endif
+  return pc;
+}
+
+void* ATTRIBUTE_NOINLINE non_inline_func();
+void* ATTRIBUTE_NOINLINE non_inline_func() {
+  void *pc = NULL;
+#ifdef TEST_X86_32_AND_64
+  __asm__ __volatile__("call 1f; 1: pop %0" : "=r"(pc));
+#endif
+  return pc;
+}
+
+static void ATTRIBUTE_NOINLINE TestWithPCInsideNonInlineFunction() {
+#if defined(TEST_X86_32_AND_64) && defined(HAVE_ATTRIBUTE_NOINLINE)
+  void *pc = non_inline_func();
+  const char *symbol = TrySymbolize(pc);
+  CHECK(symbol != NULL);
+  CHECK_STREQ(symbol, "non_inline_func");
+  cout << "Test case TestWithPCInsideNonInlineFunction passed." << endl;
+#endif
+}
+
+static void ATTRIBUTE_NOINLINE TestWithPCInsideInlineFunction() {
+#if defined(TEST_X86_32_AND_64) && defined(HAVE_ALWAYS_INLINE)
+  void *pc = inline_func();  // Must be inlined.
+  const char *symbol = TrySymbolize(pc);
+  CHECK(symbol != NULL);
+  CHECK_STREQ(symbol, __FUNCTION__);
+  cout << "Test case TestWithPCInsideInlineFunction passed." << endl;
+#endif
+}
+}
+
+// Test with a return address.
+static void ATTRIBUTE_NOINLINE TestWithReturnAddress() {
+#if defined(HAVE_ATTRIBUTE_NOINLINE)
+  void *return_address = __builtin_return_address(0);
+  const char *symbol = TrySymbolize(return_address);
+  CHECK(symbol != NULL);
+  CHECK_STREQ(symbol, "main");
+  cout << "Test case TestWithReturnAddress passed." << endl;
+#endif
+}
+
+# elif defined(OS_WINDOWS) || defined(OS_CYGWIN)
+
+#ifdef _MSC_VER
+#include <intrin.h>
+#pragma intrinsic(_ReturnAddress)
+#endif
+
+struct Foo {
+  static void func(int x);
+};
+
+__declspec(noinline) void Foo::func(int x) {
+  volatile int a = x;
+  ++a;
+}
+
+TEST(Symbolize, SymbolizeWithDemangling) {
+  Foo::func(100);
+  const char* ret = TrySymbolize((void *)(&Foo::func));
+  EXPECT_STREQ("public: static void __cdecl Foo::func(int)", ret);
+}
+
+__declspec(noinline) void TestWithReturnAddress() {
+  void *return_address =
+#ifdef __GNUC__ // Cygwin and MinGW support
+	  __builtin_return_address(0)
+#else
+	  _ReturnAddress()
+#endif
+	  ;
+  const char *symbol = TrySymbolize(return_address);
+  CHECK(symbol != NULL);
+  CHECK_STREQ(symbol, "main");
+  cout << "Test case TestWithReturnAddress passed." << endl;
+}
+# endif  // __ELF__
+#endif  // HAVE_STACKTRACE
+
+int main(int argc, char **argv) {
+  FLAGS_logtostderr = true;
+  InitGoogleLogging(argv[0]);
+  InitGoogleTest(&argc, argv);
+#if defined(HAVE_SYMBOLIZE)
+# if defined(__ELF__)
+  // We don't want to get affected by the callback interface, that may be
+  // used to install some callback function at InitGoogle() time.
+  InstallSymbolizeCallback(NULL);
+
+  TestWithPCInsideInlineFunction();
+  TestWithPCInsideNonInlineFunction();
+  TestWithReturnAddress();
+  return RUN_ALL_TESTS();
+# elif defined(OS_WINDOWS) || defined(OS_CYGWIN)
+  TestWithReturnAddress();
+  return RUN_ALL_TESTS();
+# else  // OS_WINDOWS
+  printf("PASS (no symbolize_unittest support)\n");
+  return 0;
+# endif  // __ELF__
+#else
+  printf("PASS (no symbolize support)\n");
+  return 0;
+#endif  // HAVE_SYMBOLIZE
+}