Add ChannelPosix::ResetSafely() to deal with a lingering crash

The CL [1] tightened the error check too much and revealed
an existing inconsistency and resulted a production crash.
This CL makes a workaround to that crash, turning a PCHECK()
to DPCHECK().

This is the second attempt. The first one was reverted at [2]

[1] https://crrev.com/ce44fef5fd60dd2be5c587d4b084bdcd36adcee4
[2] https://crrev.com/b83c03c7b691914a054abaab13fb9131b4e0152b

BUG=449233,448245
R=agl@chromium.org,jam@chromium.org

Committed: https://crrev.com/cf3eae19b456536c5ff8dacf8800ec09f9af4bca
Cr-Commit-Position: refs/heads/master@{#313188}

Review URL: https://codereview.chromium.org/882543002

Cr-Commit-Position: refs/heads/master@{#313334}

ipc/ipc_channel_posix.cc

@@ -189,6 +189,7 @@ ChannelPosix::ChannelPosix(const IPC::ChannelHandle& channel_handle,
       waiting_connect_(true),
       message_send_bytes_written_(0),
       pipe_name_(channel_handle.name),
+      in_dtor_(false),
       must_unlink_(false) {
   memset(input_cmsg_buf_, 0, sizeof(input_cmsg_buf_));
   if (!CreatePipe(channel_handle)) {
@@ -200,6 +201,7 @@ ChannelPosix::ChannelPosix(const IPC::ChannelHandle& channel_handle,
 }
 
 ChannelPosix::~ChannelPosix() {
+  in_dtor_ = true;
   Close();
 }
 
@@ -611,7 +613,7 @@ void ChannelPosix::ResetToAcceptingConnectionState() {
   // Unregister libevent for the unix domain socket and close it.
   read_watcher_.StopWatchingFileDescriptor();
   write_watcher_.StopWatchingFileDescriptor();
-  pipe_.reset();
+  ResetSafely(&pipe_);
 #if defined(IPC_USES_READWRITE)
   fd_pipe_.reset();
   remote_fd_pipe_.reset();
@@ -1078,6 +1080,25 @@ base::ProcessId ChannelPosix::GetSelfPID() const {
   return GetHelloMessageProcId();
 }
 
+void ChannelPosix::ResetSafely(base::ScopedFD* fd) {
+  if (!in_dtor_) {
+    fd->reset();
+    return;
+  }
+
+  // crbug.com/449233
+  // The CL [1] tightened the error check for closing FDs, but it turned
+  // out that there are existing cases that hit the newly added check.
+  // ResetSafely() is the workaround for that crash, turning it from
+  // from PCHECK() to DPCHECK() so that it doesn't crash in production.
+  // [1] https://crrev.com/ce44fef5fd60dd2be5c587d4b084bdcd36adcee4
+  int fd_to_close = fd->release();
+  if (-1 != fd_to_close) {
+    int rv = IGNORE_EINTR(close(fd_to_close));
+    DPCHECK(0 == rv);
+  }
+}
+
 //------------------------------------------------------------------------------
 // Channel's methods
 

ipc/ipc_channel_posix.h

@@ -202,6 +202,10 @@ class IPC_EXPORT ChannelPosix : public Channel,
   // implementation!
   std::vector<int> input_fds_;
 
+
+  void ResetSafely(base::ScopedFD* fd);
+  bool in_dtor_;
+
 #if defined(OS_MACOSX)
   // On OSX, sent FDs must not be closed until we get an ack.
   // Keep track of sent FDs here to make sure the remote is not