text: // Copyright 2018 The gVisor Authors.
  //
  // Licensed under the Apache License, Version 2.0 (the "License");
  // you may not use this file except in compliance with the License.
  // You may obtain a copy of the License at
  //
  //     http://www.apache.org/licenses/LICENSE-2.0
  //
  // Unless required by applicable law or agreed to in writing, software
  // distributed under the License is distributed on an "AS IS" BASIS,
  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  // See the License for the specific language governing permissions and
  // limitations under the License.
  
  #include "test/syscalls/linux/socket_unix_dgram.h"
  
  #include <stdio.h>
  #include <sys/un.h>
  
  #include "gtest/gtest.h"
  #include "absl/time/clock.h"
  #include "absl/time/time.h"
  #include "test/syscalls/linux/unix_domain_socket_test_util.h"
  #include "test/util/socket_util.h"
  #include "test/util/test_util.h"
  
  namespace gvisor {
  namespace testing {
  
  namespace {
  
  TEST_P(DgramUnixSocketPairTest, WriteOneSideClosed) {
    // FIXME(b/35925052): gVisor datagram sockets return EPIPE instead of
    // ECONNREFUSED.
    SKIP_IF(IsRunningOnGvisor());
  
    auto sockets = ASSERT_NO_ERRNO_AND_VALUE(NewSocketPair());
    ASSERT_THAT(close(sockets->release_first_fd()), SyscallSucceeds());
    constexpr char kStr[] = "abc";
    ASSERT_THAT(write(sockets->second_fd(), kStr, 3),
                SyscallFailsWithErrno(ECONNREFUSED));
  }
  
  TEST_P(DgramUnixSocketPairTest, IncreasedSocketSendBufUnblocksWrites) {
    auto sockets = ASSERT_NO_ERRNO_AND_VALUE(NewSocketPair());
    int sock = sockets->first_fd();
    int buf_size = 0;
    socklen_t buf_size_len = sizeof(buf_size);
    ASSERT_THAT(getsockopt(sock, SOL_SOCKET, SO_SNDBUF, &buf_size, &buf_size_len),
                SyscallSucceeds());
    int opts;
    ASSERT_THAT(opts = fcntl(sock, F_GETFL), SyscallSucceeds());
    opts |= O_NONBLOCK;
    ASSERT_THAT(fcntl(sock, F_SETFL, opts), SyscallSucceeds());
  
    std::vector<char> buf(buf_size / 4);
    // Write till the socket buffer is full.
    while (RetryEINTR(send)(sock, buf.data(), buf.size(), 0) != -1) {
      // Sleep to give linux a chance to move data from the send buffer to the
      // receive buffer.
      absl::SleepFor(absl::Milliseconds(10));  // 10ms.
    }
    // The last error should have been EWOULDBLOCK.
    ASSERT_EQ(errno, EWOULDBLOCK);
  
    // Now increase the socket send buffer.
    buf_size = buf_size * 2;
    ASSERT_THAT(
        setsockopt(sock, SOL_SOCKET, SO_SNDBUF, &buf_size, sizeof(buf_size)),
        SyscallSucceeds());
  
    // The send should succeed again.
    ASSERT_THAT(RetryEINTR(send)(sock, buf.data(), buf.size(), 0),
                SyscallSucceeds());
  }
  
  }  // namespace
  
  }  // namespace testing
  }  // namespace gvisor
  