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diff --git a/lib/libtsan/sanitizer_common/sanitizer_thread_arg_retval.h b/lib/libtsan/sanitizer_common/sanitizer_thread_arg_retval.h
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+++ b/lib/libtsan/sanitizer_common/sanitizer_thread_arg_retval.h
@@ -0,0 +1,117 @@
+//===-- sanitizer_thread_arg_retval.h ---------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is shared between sanitizer tools.
+//
+// Tracks thread arguments and return value for leak checking.
+//===----------------------------------------------------------------------===//
+
+#ifndef SANITIZER_THREAD_ARG_RETVAL_H
+#define SANITIZER_THREAD_ARG_RETVAL_H
+
+#include "sanitizer_common.h"
+#include "sanitizer_dense_map.h"
+#include "sanitizer_list.h"
+#include "sanitizer_mutex.h"
+
+namespace __sanitizer {
+
+// Primary goal of the class is to keep alive arg and retval pointer for leak
+// checking. However it can be used to pass those pointer into wrappers used by
+// interceptors. The difference from ThreadRegistry/ThreadList is that this
+// class keeps data up to the detach or join, as exited thread still can be
+// joined to retrive retval. ThreadRegistry/ThreadList can discard exited
+// threads immediately.
+class SANITIZER_MUTEX ThreadArgRetval {
+ public:
+  struct Args {
+    void* (*routine)(void*);
+    void* arg_retval;  // Either arg or retval.
+  };
+  void Lock() SANITIZER_ACQUIRE() { mtx_.Lock(); }
+  void CheckLocked() const SANITIZER_CHECK_LOCKED() { mtx_.CheckLocked(); }
+  void Unlock() SANITIZER_RELEASE() { mtx_.Unlock(); }
+
+  // Wraps pthread_create or similar. We need to keep object locked, to
+  // prevent child thread from proceeding without thread handle.
+  template <typename CreateFn /* returns thread id on success, or 0 */>
+  void Create(bool detached, const Args& args, const CreateFn& fn) {
+    // No need to track detached threads with no args, but we will to do as it's
+    // not expensive and less edge-cases.
+    __sanitizer::Lock lock(&mtx_);
+    if (uptr thread = fn())
+      CreateLocked(thread, detached, args);
+  }
+
+  // Returns thread arg and routine.
+  Args GetArgs(uptr thread) const;
+
+  // Mark thread as done and stores retval or remove if detached. Should be
+  // called by the thread.
+  void Finish(uptr thread, void* retval);
+
+  // Mark thread as detached or remove if done.
+  template <typename DetachFn /* returns true on success */>
+  void Detach(uptr thread, const DetachFn& fn) {
+    // Lock to prevent re-use of the thread between fn() and DetachLocked()
+    // calls.
+    __sanitizer::Lock lock(&mtx_);
+    if (fn())
+      DetachLocked(thread);
+  }
+
+  // Joins the thread.
+  template <typename JoinFn /* returns true on success */>
+  void Join(uptr thread, const JoinFn& fn) {
+    // Remember internal id of the thread to prevent re-use of the thread
+    // between fn() and AfterJoin() calls. Locking JoinFn, like in
+    // Detach(), implementation can cause deadlock.
+    auto gen = BeforeJoin(thread);
+    if (fn())
+      AfterJoin(thread, gen);
+  }
+
+  // Returns all arg and retval which are considered alive.
+  void GetAllPtrsLocked(InternalMmapVector<uptr>* ptrs);
+
+  uptr size() const {
+    __sanitizer::Lock lock(&mtx_);
+    return data_.size();
+  }
+
+  // FIXME: Add fork support. Expected users of the class are sloppy with forks
+  // anyway. We likely should lock/unlock the object to avoid deadlocks, and
+  // erase all but the current threads, so we can detect leaked arg or retval in
+  // child process.
+
+  // FIXME: Add cancelation support. Now if a thread was canceled, the class
+  // will keep pointers alive forever, missing leaks caused by cancelation.
+
+ private:
+  static const u32 kInvalidGen = UINT32_MAX;
+  struct Data {
+    Args args;
+    u32 gen;  // Avoid collision if thread id re-used.
+    bool detached;
+    bool done;
+  };
+
+  void CreateLocked(uptr thread, bool detached, const Args& args);
+  u32 BeforeJoin(uptr thread) const;
+  void AfterJoin(uptr thread, u32 gen);
+  void DetachLocked(uptr thread);
+
+  mutable Mutex mtx_;
+
+  DenseMap<uptr, Data> data_;
+  u32 gen_ = 0;
+};
+
+}  // namespace __sanitizer
+
+#endif  // SANITIZER_THREAD_ARG_RETVAL_H