Guard socket file descriptor in UDPSocketLibevent

net/udp/udp_socket_libevent.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "net/udp/udp_socket_libevent.h"
 
 #include <errno.h>
 #include <fcntl.h>
+#include <net/if.h>
 #include <netdb.h>
-#include <net/if.h>
 #include <netinet/in.h>
 #include <sys/ioctl.h>
 #include <sys/socket.h>
 
 #include "base/callback.h"
 #include "base/debug/alias.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
 #include "base/metrics/sparse_histogram.h"
 #include "base/posix/eintr_wrapper.h"
@@ skipping 28 matching lines @@
   ifr.ifr_addr.sa_family = AF_INET;
   if (!if_indextoname(index, ifr.ifr_name))
     return MapSystemError(errno);
   int rv = ioctl(socket, SIOCGIFADDR, &ifr);
   if (rv == -1)
     return MapSystemError(errno);
   *address = reinterpret_cast<sockaddr_in*>(&ifr.ifr_addr)->sin_addr.s_addr;
   return OK;
 }
 
+// On OSX the file descriptor is guarded to detect the cause of
+// crbug.com/461246. sys/guarded.h is not included in the SDK, so the API needs
+// to be defined here.

[Mark Mentovai, 2015/04/02 14:37:06]

Drive the point home by saying in the comment that this is temporary and will be
removed.

[Sergey Ulanov, 2015/04/02 18:05:42]

Added TODO to remove it.

+
+typedef uint64_t guardid_t;
+
+int guarded_close_np(int fd, const guardid_t *guard) {
+  return syscall(442, fd, guard);

[Mark Mentovai, 2015/04/02 14:37:06]

This is only available in 10.9 and 10.10. It’ll be ENOSYS elsewhere. The
majority of users are on 10.9 and 10.10, so this shouldn’t be a problem.

I recommend calling through the syscall wrappers in libSystem instead of making
the syscall() like this. You can dlsym() for "guarded_close_np" and
"change_fdguard_np". If it returns nullptr for either of those, you’ll know that
the kernel doesn’t provide file descriptor guards, and you can fall back to
using close() instead of guarded_close_np().

[Sergey Ulanov, 2015/04/02 18:05:42]

Done.

+}
+int change_fdguard_np(int fd, const guardid_t *guard, u_int flags,
+    const guardid_t *nguard, u_int nflags, int *fdflagsp) {
+  return syscall(444, fd, guard, flags, nguard, nflags, fdflagsp);
+}
+
+const unsigned int GUARD_CLOSE = 1u<<0;
+const unsigned int GUARD_DUP = 1u<<1;
+
+const guardid_t kSocketFdGuard = 0xD712BC0BC9A4EAD4;
+
 #endif  // OS_MACOSX
 
 }  // namespace
 
 UDPSocketLibevent::UDPSocketLibevent(
     DatagramSocket::BindType bind_type,
     const RandIntCallback& rand_int_cb,
     net::NetLog* net_log,
     const net::NetLog::Source& source)
         : socket_(kInvalidSocket),
@@ skipping 22 matching lines @@
 }
 
 int UDPSocketLibevent::Open(AddressFamily address_family) {
   DCHECK(CalledOnValidThread());
   DCHECK_EQ(socket_, kInvalidSocket);
 
   addr_family_ = ConvertAddressFamily(address_family);
   socket_ = CreatePlatformSocket(addr_family_, SOCK_DGRAM, 0);
   if (socket_ == kInvalidSocket)
     return MapSystemError(errno);
+#if defined(OS_MACOSX)
+  PCHECK(change_fdguard_np(socket_, NULL, 0, &kSocketFdGuard,
+                           GUARD_CLOSE | GUARD_DUP, NULL) == 0);
+#endif  // OS_MACOSX
   if (SetNonBlocking(socket_)) {
     const int err = MapSystemError(errno);
     Close();
     return err;
   }
   return OK;
 }
 
 void UDPSocketLibevent::Close() {
   DCHECK(CalledOnValidThread());
 
   if (socket_ == kInvalidSocket)
     return;
 
   // Zero out any pending read/write callback state.
   read_buf_ = NULL;
   read_buf_len_ = 0;
   read_callback_.Reset();
   recv_from_address_ = NULL;
   write_buf_ = NULL;
   write_buf_len_ = 0;
   write_callback_.Reset();
   send_to_address_.reset();
 
   bool ok = read_socket_watcher_.StopWatchingFileDescriptor();
   DCHECK(ok);
   ok = write_socket_watcher_.StopWatchingFileDescriptor();
   DCHECK(ok);
 
+#if defined(OS_MACOSX)
+  PCHECK(IGNORE_EINTR(guarded_close_np(socket_, &kSocketFdGuard)) == 0);
+#else
   PCHECK(IGNORE_EINTR(close(socket_)) == 0);
+#endif  // OS_MACOSX
 
   socket_ = kInvalidSocket;
   addr_family_ = 0;
   is_connected_ = false;
 }
 
 int UDPSocketLibevent::GetPeerAddress(IPEndPoint* address) const {
   DCHECK(CalledOnValidThread());
   DCHECK(address);
   if (!is_connected())
@@ skipping 603 matching lines @@
     return MapSystemError(errno);
 
   return OK;
 }
 
 void UDPSocketLibevent::DetachFromThread() {
   base::NonThreadSafe::DetachFromThread();
 }
 
 }  // namespace net