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//===-- 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
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