commit 1af21effefbd57060f6e215e893ccddd10776f2a
author Sim Sun <simsun@fb.com> Wed Mar 02 22:15:27 2022 -0800
committer Christopher Ferris <cferris@google.com> Thu Mar 03 10:40:56 2022 -0800
tree 65d7fd8a5b9f0183014df71e386c5b2aa2e4a6fb
parent 875fd55938fe993973948bfb59b9c3814c338ef4

Allow unwinding main thread in ThreadUnwinder.

The check in ThreadUnwinder was overly aggressive, it should only
disallow unwinding itself. Unfortunately, it only disallowed
unwinding the main thread.

Add new unit tests to verify this behavior.

Test: New unit tests pass that verify thread unwinding behavior.

Signed-off-by: Sim Sun <simsun@fb.com>
Change-Id: If75399911f2f98f3155592fc292341d7b9e5e023

libunwindstack/ThreadUnwinder.cpp

diff --git a/libunwindstack/ThreadUnwinder.cpp b/libunwindstack/ThreadUnwinder.cpp
index 9a8a0a6..2bdb910 100644
--- a/libunwindstack/ThreadUnwinder.cpp
+++ b/libunwindstack/ThreadUnwinder.cpp
@@ -149,7 +149,7 @@
                                       const std::vector<std::string>* initial_map_names_to_skip,
                                       const std::vector<std::string>* map_suffixes_to_ignore) {
   ClearErrors();
-  if (tid == pid_) {
+  if (tid == static_cast<pid_t>(android::base::GetThreadId())) {
     last_error_.code = ERROR_UNSUPPORTED;
     return;
   }

libunwindstack/tests/UnwindTest.cpp

diff --git a/libunwindstack/tests/UnwindTest.cpp b/libunwindstack/tests/UnwindTest.cpp
index 80f931b..2ed1b9b 100644
--- a/libunwindstack/tests/UnwindTest.cpp
+++ b/libunwindstack/tests/UnwindTest.cpp
@@ -570,6 +570,28 @@
   EXPECT_EQ(ERROR_UNSUPPORTED, unwinder.LastErrorCode());
 }
 
+TEST_F(UnwindTest, thread_unwind_cur_thread) {
+  std::thread thread([]() {
+    ThreadUnwinder unwinder(512);
+    ASSERT_TRUE(unwinder.Init());
+    unwinder.UnwindWithSignal(SIGRTMIN, android::base::GetThreadId());
+    EXPECT_EQ(0U, unwinder.NumFrames());
+    EXPECT_EQ(ERROR_UNSUPPORTED, unwinder.LastErrorCode());
+  });
+  thread.join();
+}
+
+TEST_F(UnwindTest, thread_unwind_cur_pid_from_thread) {
+  std::thread thread([]() {
+    ThreadUnwinder unwinder(512);
+    ASSERT_TRUE(unwinder.Init());
+    unwinder.UnwindWithSignal(SIGRTMIN, getpid());
+    EXPECT_NE(0U, unwinder.NumFrames());
+    EXPECT_NE(ERROR_UNSUPPORTED, unwinder.LastErrorCode());
+  });
+  thread.join();
+}
+
 static std::thread* CreateUnwindThread(std::atomic_int& tid, ThreadUnwinder& unwinder,
                                        std::atomic_bool& start_unwinding,
                                        std::atomic_int& unwinders) {