From 3ac5f621cda8c168e5d3e18391fc058f16e065a4 Mon Sep 17 00:00:00 2001
From: Jan Oravec <jan@fb.com>
Date: Thu, 13 Jun 2013 12:40:52 -0700
Subject: [PATCH] Recover from C++ exceptions

Recover from C++ exceptions so that PSP does not think ASIO is running. Fixes a segfault when ASIO fails on internal invariant violation in runUntil() with m_current == nullptr.
---
 hphp/runtime/ext/asio/asio_context.cpp             | 11 +++++++++--
 hphp/runtime/ext/asio/asio_session.cpp             |  6 ++++++
 hphp/runtime/ext/asio/asio_session.h               | 13 +++++++++++++
 hphp/runtime/ext/asio/continuation_wait_handle.cpp |  4 ++++
 hphp/runtime/ext/asio/waitable_wait_handle.cpp     | 20 ++++++--------------
 5 files changed, 38 insertions(+), 16 deletions(-)

diff --git a/hphp/runtime/ext/asio/asio_context.cpp b/hphp/runtime/ext/asio/asio_context.cpp
index b7e7ed19e41..8e93bb50e09 100644
--- a/hphp/runtime/ext/asio/asio_context.cpp
+++ b/hphp/runtime/ext/asio/asio_context.cpp
@@ -96,6 +96,10 @@ void AsioContext::runUntil(c_WaitableWaitHandle* wait_handle) {
   auto session = AsioSession::Get();
   uint8_t check_ete_counter = 0;
 
+  if (!session->hasAbruptInterruptException()) {
+    session->initAbruptInterruptException();
+  }
+
   while (!wait_handle->isFinished()) {
     // process ready external thread events once per 256 other events
     // (when 8-bit check_ete_counter overflows)
@@ -113,9 +117,12 @@ void AsioContext::runUntil(c_WaitableWaitHandle* wait_handle) {
       auto current = m_runnableQueue.front();
       m_runnableQueue.pop();
       m_current = current;
+      auto exit_guard = folly::makeGuard([&] {
+        m_current = nullptr;
+        decRefObj(current);
+      });
+
       m_current->run();
-      m_current = nullptr;
-      decRefObj(current);
       continue;
     }
 
diff --git a/hphp/runtime/ext/asio/asio_session.cpp b/hphp/runtime/ext/asio/asio_session.cpp
index a0021c4f35c..7441d087159 100644
--- a/hphp/runtime/ext/asio/asio_session.cpp
+++ b/hphp/runtime/ext/asio/asio_session.cpp
@@ -118,6 +118,12 @@ void AsioSession::enqueueExternalThreadEvent(c_ExternalThreadEventWaitHandle* wa
   }
 }
 
+void AsioSession::initAbruptInterruptException() {
+  assert(!hasAbruptInterruptException());
+  m_abruptInterruptException = SystemLib::AllocInvalidOperationExceptionObject(
+    "The request was abruptly interrupted.");
+}
+
 void AsioSession::onFailed(CObjRef exception) {
   if (m_onFailedCallback.get()) {
     try {
diff --git a/hphp/runtime/ext/asio/asio_session.h b/hphp/runtime/ext/asio/asio_session.h
index 7d606bab0a2..74bd8bd9136 100644
--- a/hphp/runtime/ext/asio/asio_session.h
+++ b/hphp/runtime/ext/asio/asio_session.h
@@ -83,6 +83,17 @@ class AsioSession {
     c_ExternalThreadEventWaitHandle* waitForExternalThreadEvents();
     void enqueueExternalThreadEvent(c_ExternalThreadEventWaitHandle* wait_handle);
 
+    // abrupt interrupt exception
+    CObjRef getAbruptInterruptException() {
+      return m_abruptInterruptException;
+    }
+
+    bool hasAbruptInterruptException() {
+      return m_abruptInterruptException.get();
+    }
+
+    void initAbruptInterruptException();
+
     // callback: on failed
     void setOnFailedCallback(ObjectData* on_failed_callback) {
       assert(!on_failed_callback || on_failed_callback->instanceof(c_Closure::s_cls));
@@ -162,6 +173,8 @@ class AsioSession {
     std::mutex m_readyExternalThreadEventsMutex;
     std::condition_variable m_readyExternalThreadEventsCondition;
 
+    Object m_abruptInterruptException;
+
     Object m_onContinuationCreateCallback;
     Object m_onContinuationYieldCallback;
     Object m_onContinuationSuccessCallback;
diff --git a/hphp/runtime/ext/asio/continuation_wait_handle.cpp b/hphp/runtime/ext/asio/continuation_wait_handle.cpp
index bdb795d5b37..3e8de6d513c 100644
--- a/hphp/runtime/ext/asio/continuation_wait_handle.cpp
+++ b/hphp/runtime/ext/asio/continuation_wait_handle.cpp
@@ -192,6 +192,10 @@ void c_ContinuationWaitHandle::run() {
   } catch (const Object& exception) {
     // process exception thrown by generator or blockOn cycle detection
     markAsFailed(exception);
+  } catch (...) {
+    // process C++ exception
+    markAsFailed(AsioSession::Get()->getAbruptInterruptException());
+    throw;
   }
 }
 
diff --git a/hphp/runtime/ext/asio/waitable_wait_handle.cpp b/hphp/runtime/ext/asio/waitable_wait_handle.cpp
index e40ae8b5f3b..6e7b2f30937 100644
--- a/hphp/runtime/ext/asio/waitable_wait_handle.cpp
+++ b/hphp/runtime/ext/asio/waitable_wait_handle.cpp
@@ -140,25 +140,17 @@ void c_WaitableWaitHandle::join() {
 
   // enter new asio context and set up guard that will exit once we are done
   session->enterContext();
+  auto exit_guard = folly::makeGuard([&] { session->exitContext(); });
 
   assert(session->isInContext());
   assert(!session->getCurrentContext()->isRunning());
 
-  try {
-    // import this wait handle to the newly created context
-    // throws if cross-context cycle found
-    enterContext(session->getCurrentContextIdx());
-
-    // run queues until we are finished
-    session->getCurrentContext()->runUntil(this);
-  } catch (const Object& exception) {
-    // recover from PHP exceptions; HPHP internal exceptions are deliberately
-    // ignored as there is no easy way to recover from them
-    session->exitContext();
-    throw;
-  }
-  session->exitContext();
+  // import this wait handle to the newly created context
+  // throws if cross-context cycle found
+  enterContext(session->getCurrentContextIdx());
 
+  // run queues until we are finished
+  session->getCurrentContext()->runUntil(this);
   assert(isFinished());
 }
 
-- 
2.11.4.GIT