Merge "Properly fail with ESRCH when pthread_killing an exited thread."ndk-r19cndk-r19bndk-r19-beta2ndk-r19-beta1ndk-r19ndk-release-r19

2 files changed, 23 insertions, 1 deletions

diff --git a/libc/bionic/pthread_kill.cpp b/libc/bionic/pthread_kill.cpp
index 3761a7589..153157496 100644
--- a/libc/bionic/pthread_kill.cpp
+++ b/libc/bionic/pthread_kill.cpp
@@ -36,7 +36,9 @@ int pthread_kill(pthread_t t, int sig) {
   ErrnoRestorer errno_restorer;
 
   pid_t tid = pthread_gettid_np(t);
-  if (tid == -1) return ESRCH;
+
+  // tid gets reset to 0 on thread exit by CLONE_CHILD_CLEARTID.
+  if (tid == 0 || tid == -1) return ESRCH;
 
   return (tgkill(getpid(), tid, sig) == -1) ? errno : 0;
 }
diff --git a/tests/pthread_test.cpp b/tests/pthread_test.cpp
index fc8945ce8..e68f1ff03 100644
--- a/tests/pthread_test.cpp
+++ b/tests/pthread_test.cpp
@@ -31,6 +31,7 @@
 #include <unwind.h>
 
 #include <atomic>
+#include <future>
 #include <vector>
 
 #include <android-base/parseint.h>
@@ -539,6 +540,25 @@ TEST(pthread, pthread_kill__in_signal_handler) {
   ASSERT_EQ(0, pthread_kill(pthread_self(), SIGALRM));
 }
 
+TEST(pthread, pthread_kill__exited_thread) {
+  static std::promise<pid_t> tid_promise;
+  pthread_t thread;
+  ASSERT_EQ(0, pthread_create(&thread, nullptr,
+                              [](void*) -> void* {
+                                tid_promise.set_value(gettid());
+                                return nullptr;
+                              },
+                              nullptr));
+
+  pid_t tid = tid_promise.get_future().get();
+  while (TEMP_FAILURE_RETRY(syscall(__NR_tgkill, getpid(), tid, 0)) != -1) {
+    continue;
+  }
+  ASSERT_EQ(ESRCH, errno);
+
+  ASSERT_EQ(ESRCH, pthread_kill(thread, 0));
+}
+
 TEST_F(pthread_DeathTest, pthread_detach__no_such_thread) {
   pthread_t dead_thread;
   MakeDeadThread(dead_thread);