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Date:      Thu, 10 Oct 2019 20:33:56 +0000 (UTC)
From:      Dimitry Andric <dim@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r353416 - head/contrib/llvm/tools/lldb/source/Plugins/Process/FreeBSD
Message-ID:  <201910102033.x9AKXueB073420@repo.freebsd.org>

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Author: dim
Date: Thu Oct 10 20:33:55 2019
New Revision: 353416
URL: https://svnweb.freebsd.org/changeset/base/353416

Log:
  Pull in r374444 from upstream lldb trunk (by me):
  
    Fix process launch failure on FreeBSD after r365761
  
    Summary:
    After rLLDB365761, and with `LLVM_ENABLE_ABI_BREAKING_CHECKS`
    enabled, launching any process on FreeBSD crashes lldb with:
  
    ```
    Expected<T> must be checked before access or destruction.
    Expected<T> value was in success state. (Note: Expected<T> values in
    success mode must still be checked prior to being destroyed).
    ```
  
    This is because `m_operation_thread` and `m_monitor_thread` were
    wrapped in `llvm::Expected<>`, but this requires the objects to be
    correctly initialized before accessing them.
  
    To fix the crashes, use `llvm::Optional<>` for the members (as
    indicated by labath), and use local variables to store the return
    values of `LaunchThread` and `StartMonitoringChildProcess`.  Then,
    only assign to the member variables after checking if the return
    values indicated success.
  
    Reviewers: devnexen, emaste, MaskRay, mgorny
  
    Reviewed By: devnexen
  
    Subscribers: jfb, labath, krytarowski, lldb-commits
  
    Differential Revision: https://reviews.llvm.org/D68723
  
  PR:		241137
  MFC after:	1 month
  X-MFC-With:	r353358

Modified:
  head/contrib/llvm/tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp
  head/contrib/llvm/tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.h

Modified: head/contrib/llvm/tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp
==============================================================================
--- head/contrib/llvm/tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp	Thu Oct 10 20:30:54 2019	(r353415)
+++ head/contrib/llvm/tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.cpp	Thu Oct 10 20:33:55 2019	(r353416)
@@ -708,7 +708,7 @@ ProcessMonitor::ProcessMonitor(
     const lldb_private::ProcessLaunchInfo & /* launch_info */,
     lldb_private::Status &error)
     : m_process(static_cast<ProcessFreeBSD *>(process)),
-      m_operation_thread(nullptr), m_monitor_thread(nullptr), m_pid(LLDB_INVALID_PROCESS_ID), m_terminal_fd(-1), m_operation(0) {
+      m_operation_thread(), m_monitor_thread(), m_pid(LLDB_INVALID_PROCESS_ID), m_terminal_fd(-1), m_operation(0) {
   using namespace std::placeholders;
 
   std::unique_ptr<LaunchArgs> args(
@@ -735,20 +735,22 @@ ProcessMonitor::ProcessMonitor(
   }
 
   // Finally, start monitoring the child process for change in state.
-  m_monitor_thread = Host::StartMonitoringChildProcess(
+  llvm::Expected<lldb_private::HostThread> monitor_thread =
+    Host::StartMonitoringChildProcess(
       std::bind(&ProcessMonitor::MonitorCallback, this, _1, _2, _3, _4),
       GetPID(), true);
-  if (!m_monitor_thread->IsJoinable()) {
+  if (!monitor_thread || !monitor_thread->IsJoinable()) {
     error.SetErrorToGenericError();
     error.SetErrorString("Process launch failed.");
     return;
   }
+  m_monitor_thread = *monitor_thread;
 }
 
 ProcessMonitor::ProcessMonitor(ProcessFreeBSD *process, lldb::pid_t pid,
                                lldb_private::Status &error)
     : m_process(static_cast<ProcessFreeBSD *>(process)),
-      m_operation_thread(nullptr), m_monitor_thread(nullptr), m_pid(pid), m_terminal_fd(-1), m_operation(0) {
+      m_operation_thread(), m_monitor_thread(), m_pid(pid), m_terminal_fd(-1), m_operation(0) {
   using namespace std::placeholders;
 
   sem_init(&m_operation_pending, 0, 0);
@@ -773,14 +775,16 @@ ProcessMonitor::ProcessMonitor(ProcessFreeBSD *process
   }
 
   // Finally, start monitoring the child process for change in state.
-  m_monitor_thread = Host::StartMonitoringChildProcess(
+  llvm::Expected<lldb_private::HostThread> monitor_thread =
+    Host::StartMonitoringChildProcess(
       std::bind(&ProcessMonitor::MonitorCallback, this, _1, _2, _3, _4),
       GetPID(), true);
-  if (!m_monitor_thread->IsJoinable()) {
+  if (!monitor_thread || !monitor_thread->IsJoinable()) {
     error.SetErrorToGenericError();
     error.SetErrorString("Process attach failed.");
     return;
   }
+  m_monitor_thread = *monitor_thread;
 }
 
 ProcessMonitor::~ProcessMonitor() { StopMonitor(); }
@@ -789,13 +793,15 @@ ProcessMonitor::~ProcessMonitor() { StopMonitor(); }
 void ProcessMonitor::StartLaunchOpThread(LaunchArgs *args, Status &error) {
   static const char *g_thread_name = "freebsd.op";
 
-  if (m_operation_thread->IsJoinable())
+  if (m_operation_thread && m_operation_thread->IsJoinable())
     return;
 
-  m_operation_thread =
-      ThreadLauncher::LaunchThread(g_thread_name, LaunchOpThread, args);
-  if (!m_operation_thread)
-     error = m_operation_thread.takeError();
+  llvm::Expected<lldb_private::HostThread> operation_thread =
+    ThreadLauncher::LaunchThread(g_thread_name, LaunchOpThread, args);
+  if (operation_thread)
+    m_operation_thread = *operation_thread;
+  else
+    error = operation_thread.takeError();
 }
 
 void *ProcessMonitor::LaunchOpThread(void *arg) {
@@ -957,14 +963,15 @@ void ProcessMonitor::StartAttachOpThread(AttachArgs *a
                                          lldb_private::Status &error) {
   static const char *g_thread_name = "freebsd.op";
 
-  if (m_operation_thread->IsJoinable())
+  if (m_operation_thread && m_operation_thread->IsJoinable())
     return;
 
-  m_operation_thread =
-      ThreadLauncher::LaunchThread(g_thread_name, AttachOpThread, args);
-
-  if (!m_operation_thread)
-	error = m_operation_thread.takeError();
+  llvm::Expected<lldb_private::HostThread> operation_thread =
+    ThreadLauncher::LaunchThread(g_thread_name, AttachOpThread, args);
+  if (operation_thread)
+    m_operation_thread = *operation_thread;
+  else
+    error = operation_thread.takeError();
 }
 
 void *ProcessMonitor::AttachOpThread(void *arg) {
@@ -1384,7 +1391,7 @@ bool ProcessMonitor::DupDescriptor(const FileSpec &fil
 }
 
 void ProcessMonitor::StopMonitoringChildProcess() {
-  if (m_monitor_thread->IsJoinable()) {
+  if (m_monitor_thread && m_monitor_thread->IsJoinable()) {
     m_monitor_thread->Cancel();
     m_monitor_thread->Join(nullptr);
     m_monitor_thread->Reset();
@@ -1422,10 +1429,9 @@ void ProcessMonitor::StopMonitor() {
 bool ProcessMonitor::WaitForInitialTIDStop(lldb::tid_t tid) { return true; }
 
 void ProcessMonitor::StopOpThread() {
-  if (!m_operation_thread->IsJoinable())
-    return;
-
-  m_operation_thread->Cancel();
-  m_operation_thread->Join(nullptr);
-  m_operation_thread->Reset();
+  if (m_operation_thread && m_operation_thread->IsJoinable()) {
+    m_operation_thread->Cancel();
+    m_operation_thread->Join(nullptr);
+    m_operation_thread->Reset();
+  }
 }

Modified: head/contrib/llvm/tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.h
==============================================================================
--- head/contrib/llvm/tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.h	Thu Oct 10 20:30:54 2019	(r353415)
+++ head/contrib/llvm/tools/lldb/source/Plugins/Process/FreeBSD/ProcessMonitor.h	Thu Oct 10 20:33:55 2019	(r353416)
@@ -183,8 +183,8 @@ class ProcessMonitor { (public)
 private:
   ProcessFreeBSD *m_process;
 
-  llvm::Expected<lldb_private::HostThread> m_operation_thread;
-  llvm::Expected<lldb_private::HostThread> m_monitor_thread;
+  llvm::Optional<lldb_private::HostThread> m_operation_thread;
+  llvm::Optional<lldb_private::HostThread> m_monitor_thread;
   lldb::pid_t m_pid;
 
   int m_terminal_fd;



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