From 9b24e29d7275dbf813238515e9196529f72a7416 Mon Sep 17 00:00:00 2001
From: Kostya Serebryany <kcc@google.com>
Date: Fri, 16 Oct 2015 23:04:31 +0000
Subject: [PATCH] [libFuzzer] print a stack trace on timeout

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@250571 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/Fuzzer/FuzzerInternal.h | 1 +
 lib/Fuzzer/FuzzerLoop.cpp   | 9 +++++++++
 lib/Fuzzer/FuzzerUtil.cpp   | 2 ++
 lib/Fuzzer/test/fuzzer.test | 5 +++++
 4 files changed, 17 insertions(+)

diff --git a/lib/Fuzzer/FuzzerInternal.h b/lib/Fuzzer/FuzzerInternal.h
index c672f23d95f..a720adb21e4 100644
--- a/lib/Fuzzer/FuzzerInternal.h
+++ b/lib/Fuzzer/FuzzerInternal.h
@@ -56,6 +56,7 @@ bool ToASCII(Unit &U);
 bool IsASCII(const Unit &U);
 
 int NumberOfCpuCores();
+int GetPid();
 
 // Dictionary.
 
diff --git a/lib/Fuzzer/FuzzerLoop.cpp b/lib/Fuzzer/FuzzerLoop.cpp
index 93054298bc4..a642bbbf5cb 100644
--- a/lib/Fuzzer/FuzzerLoop.cpp
+++ b/lib/Fuzzer/FuzzerLoop.cpp
@@ -13,6 +13,10 @@
 #include <sanitizer/coverage_interface.h>
 #include <algorithm>
 
+extern "C" {
+__attribute__((weak)) void __sanitizer_print_stack_trace();
+}
+
 namespace fuzzer {
 static const size_t kMaxUnitSizeToPrint = 256;
 
@@ -76,6 +80,11 @@ void Fuzzer::AlarmCallback() {
       PrintUnitInASCIIOrTokens(CurrentUnit, "\n");
     }
     WriteUnitToFileWithPrefix(CurrentUnit, "timeout-");
+    Printf("==%d== ERROR: libFuzzer: timeout after %d seconds\n", GetPid(),
+           Seconds);
+    if (__sanitizer_print_stack_trace)
+      __sanitizer_print_stack_trace();
+    Printf("SUMMARY: libFuzzer: timeout\n");
     exit(1);
   }
 }
diff --git a/lib/Fuzzer/FuzzerUtil.cpp b/lib/Fuzzer/FuzzerUtil.cpp
index a8856ab3bce..7a04898cf36 100644
--- a/lib/Fuzzer/FuzzerUtil.cpp
+++ b/lib/Fuzzer/FuzzerUtil.cpp
@@ -166,4 +166,6 @@ bool ParseDictionaryFile(const std::string &Text, std::vector<Unit> *Units) {
   return true;
 }
 
+int GetPid() { return getpid(); }
+
 }  // namespace fuzzer
diff --git a/lib/Fuzzer/test/fuzzer.test b/lib/Fuzzer/test/fuzzer.test
index dccc5e48250..1c29c75d85a 100644
--- a/lib/Fuzzer/test/fuzzer.test
+++ b/lib/Fuzzer/test/fuzzer.test
@@ -14,6 +14,11 @@ MaxTotalTime: Done {{.*}} runs in {{.}} second(s)
 RUN: not LLVMFuzzer-TimeoutTest -timeout=5 2>&1 | FileCheck %s --check-prefix=TimeoutTest
 TimeoutTest: ALARM: working on the last Unit for
 TimeoutTest: Test unit written to ./timeout-
+TimeoutTest: == ERROR: libFuzzer: timeout after
+TimeoutTest: #0
+TimeoutTest: #1
+TimeoutTest: #2
+TimeoutTest: SUMMARY: libFuzzer: timeout
 
 RUN: not LLVMFuzzer-TimeoutTest -timeout=5 -test_single_input=%S/hi.txt 2>&1 | FileCheck %s --check-prefix=SingleInputTimeoutTest
 SingleInputTimeoutTest: ALARM: working on the last Unit for
-- 
2.34.1