GTTF: Make Linux stack dump signal handler async-signal safe.

base/debug/stack_trace_unittest.cc

Index: base/debug/stack_trace_unittest.cc
diff --git a/base/debug/stack_trace_unittest.cc b/base/debug/stack_trace_unittest.cc
index 6a35dac7a4bef47c779884e9c6aaaaf7904b44bc..717b8837e5dac21048f21df9a0b2064d37cccd46 100644
--- a/base/debug/stack_trace_unittest.cc
+++ b/base/debug/stack_trace_unittest.cc
@@ -2,16 +2,23 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#include <limits>
 #include <sstream>
 #include <string>
 
 #include "base/debug/stack_trace.h"
 #include "base/logging.h"
+#include "base/process_util.h"
+#include "base/test/multiprocess_test.h"
+#include "base/test/test_timeouts.h"
 #include "testing/gtest/include/gtest/gtest.h"
+#include "testing/multiprocess_func_list.h"
 
 namespace base {
 namespace debug {
 
+typedef MultiProcessTest StackTraceTest;
+
 // Note: On Linux, this test currently only fully works on Debug builds.
 // See comments in the #ifdef soup if you intend to change this.
 #if defined(OS_WIN)
@@ -20,7 +27,7 @@ namespace debug {
 #else
 #define MAYBE_OutputToStream OutputToStream
 #endif
-TEST(StackTrace, MAYBE_OutputToStream) {
+TEST_F(StackTraceTest, MAYBE_OutputToStream) {
   StackTrace trace;
 
   // Dump the trace into a string.
@@ -69,7 +76,7 @@ TEST(StackTrace, MAYBE_OutputToStream) {
       << backtrace_message;
 
 #endif
-#elif defined(__GLIBCXX__)
+#elif defined(USE_SYMBOLIZE)
   // This branch is for gcc-compiled code, but not Mac due to the
   // above #if.
   // Expect a demangled symbol.
@@ -103,8 +110,24 @@ TEST(StackTrace, MAYBE_OutputToStream) {
 #endif  // define(OS_MACOSX)
 }
 
+MULTIPROCESS_TEST_MAIN(MismatchedMallocChildProcess) {
+  char* pointer = new char[10];
+  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) {
+  ProcessHandle child = this->SpawnChild("MismatchedMallocChildProcess", false);
+  ASSERT_NE(kNullProcessHandle, child);
+  ASSERT_TRUE(WaitForSingleProcess(child, TestTimeouts::action_timeout()));
+}
+
 // The test is used for manual testing, e.g., to see the raw output.
-TEST(StackTrace, DebugOutputToStream) {
+TEST_F(StackTraceTest, DebugOutputToStream) {
   StackTrace trace;
   std::ostringstream os;
   trace.OutputToStream(&os);
@@ -112,9 +135,46 @@ TEST(StackTrace, DebugOutputToStream) {
 }
 
 // The test is used for manual testing, e.g., to see the raw output.
-TEST(StackTrace, DebugPrintBacktrace) {
+TEST_F(StackTraceTest, DebugPrintBacktrace) {
   StackTrace().PrintBacktrace();
 }
 
+namespace {
+
+std::string itoa_r_wrapper(intptr_t i, size_t sz, int base) {
+  char buffer[1024];
+  CHECK_LE(sz, sizeof(buffer));
+
+  char* result = internal::itoa_r(i, buffer, sz, base);
+  EXPECT_TRUE(result);
+  return std::string(buffer);
+}
+
+}  // namespace
+
+#if defined(OS_POSIX)
+TEST_F(StackTraceTest, itoa_r) {
+  EXPECT_EQ("0", itoa_r_wrapper(0, 128, 10));
+  EXPECT_EQ("-1", itoa_r_wrapper(-1, 128, 10));

[jar (doing other things), 2012/11/07 00:32:07]

You should do this base 16, and get (on your 64 bit machine):

"FFFFFFFFFFFFFFFF"

+
+  // Test edge cases.
+  EXPECT_EQ("-9223372036854775808",

[jar (doing other things), 2012/11/07 00:32:07]

On a 32 bit machine, this will give a different answer.  You can base it in
sizeof(intptr_t).

[Paweł Hajdan Jr., 2012/11/07 00:52:28]

Do we have any 32-bit machines we test on? In case a trybot or buildbot fails on
this I'm defnitely going to add 32-bit case.

[Scott Hess - ex-Googler, 2012/11/07 01:02:26]

OSX still builds 32-bit.

+            itoa_r_wrapper(std::numeric_limits<intptr_t>::min(), 128, 10));
+  EXPECT_EQ("9223372036854775807",
+            itoa_r_wrapper(std::numeric_limits<intptr_t>::max(), 128, 10));

[jar (doing other things), 2012/11/07 00:32:07]

Also do this verification, base 16.  The results should be (on your 64 bit
machine):

max ==> "7FFFFFFFFFFFFFFF"

min==> "8000000000000000"

Again, results will vary depending on word size. There should be no 

+
+  // Test hex output.
+  EXPECT_EQ("688", itoa_r_wrapper(0x688, 128, 16));
+  EXPECT_EQ("deadbeef", itoa_r_wrapper(0xdeadbeef, 128, 16));
+
+  // Check that itoa_r respects passed buffer size limit.
+  char buffer[1024];
+  EXPECT_TRUE(internal::itoa_r(0xdeadbeef, buffer, 10, 16));
+  EXPECT_TRUE(internal::itoa_r(0xdeadbeef, buffer, 9, 16));
+  EXPECT_FALSE(internal::itoa_r(0xdeadbeef, buffer, 8, 16));
+  EXPECT_FALSE(internal::itoa_r(0xdeadbeef, buffer, 7, 16));
+}
+#endif  // defined(OS_POSIX)
+
 }  // namespace debug
 }  // namespace base