169 lines
5.8 KiB
C++
169 lines
5.8 KiB
C++
// Copyright 2018 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include <fcntl.h>
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#include <sys/resource.h>
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#include <sys/select.h>
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#include <sys/time.h>
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#include <climits>
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#include <csignal>
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#include <cstdio>
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#include "gtest/gtest.h"
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#include "gtest/gtest.h"
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#include "absl/time/time.h"
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#include "test/syscalls/linux/base_poll_test.h"
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#include "test/util/file_descriptor.h"
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#include "test/util/multiprocess_util.h"
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#include "test/util/posix_error.h"
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#include "test/util/rlimit_util.h"
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#include "test/util/temp_path.h"
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#include "test/util/test_util.h"
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namespace gvisor {
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namespace testing {
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namespace {
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class SelectTest : public BasePollTest {
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protected:
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void SetUp() override { BasePollTest::SetUp(); }
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void TearDown() override { BasePollTest::TearDown(); }
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};
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// See that when there are no FD sets, select behaves like sleep.
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TEST_F(SelectTest, NullFds) {
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struct timeval timeout = absl::ToTimeval(absl::Milliseconds(10));
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ASSERT_THAT(select(0, nullptr, nullptr, nullptr, &timeout),
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SyscallSucceeds());
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EXPECT_EQ(timeout.tv_sec, 0);
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EXPECT_EQ(timeout.tv_usec, 0);
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timeout = absl::ToTimeval(absl::Milliseconds(10));
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ASSERT_THAT(select(1, nullptr, nullptr, nullptr, &timeout),
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SyscallSucceeds());
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EXPECT_EQ(timeout.tv_sec, 0);
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EXPECT_EQ(timeout.tv_usec, 0);
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}
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TEST_F(SelectTest, NegativeNfds) {
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EXPECT_THAT(select(-1, nullptr, nullptr, nullptr, nullptr),
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SyscallFailsWithErrno(EINVAL));
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EXPECT_THAT(select(-100000, nullptr, nullptr, nullptr, nullptr),
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SyscallFailsWithErrno(EINVAL));
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EXPECT_THAT(select(INT_MIN, nullptr, nullptr, nullptr, nullptr),
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SyscallFailsWithErrno(EINVAL));
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}
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TEST_F(SelectTest, ClosedFds) {
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auto temp_file = ASSERT_NO_ERRNO_AND_VALUE(TempPath::CreateFile());
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FileDescriptor fd =
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ASSERT_NO_ERRNO_AND_VALUE(Open(temp_file.path(), O_RDONLY));
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// We can't rely on a file descriptor being closed in a multi threaded
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// application so fork to get a clean process.
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EXPECT_THAT(InForkedProcess([&] {
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int fd_num = fd.get();
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fd.reset();
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fd_set read_set;
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FD_ZERO(&read_set);
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FD_SET(fd_num, &read_set);
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struct timeval timeout =
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absl::ToTimeval(absl::Milliseconds(10));
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TEST_PCHECK(select(fd_num + 1, &read_set, nullptr, nullptr,
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&timeout) != 0);
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TEST_PCHECK(errno == EBADF);
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}),
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IsPosixErrorOkAndHolds(0));
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}
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TEST_F(SelectTest, ZeroTimeout) {
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struct timeval timeout = {};
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EXPECT_THAT(select(1, nullptr, nullptr, nullptr, &timeout),
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SyscallSucceeds());
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// Ignore timeout as its value is now undefined.
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}
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// If random S/R interrupts the select, SIGALRM may be delivered before select
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// restarts, causing the select to hang forever.
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TEST_F(SelectTest, NoTimeout_NoRandomSave) {
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// When there's no timeout, select may never return so set a timer.
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SetTimer(absl::Milliseconds(100));
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// See that we get interrupted by the timer.
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ASSERT_THAT(select(1, nullptr, nullptr, nullptr, nullptr),
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SyscallFailsWithErrno(EINTR));
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EXPECT_TRUE(TimerFired());
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}
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TEST_F(SelectTest, InvalidTimeoutNegative) {
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struct timeval timeout = absl::ToTimeval(absl::Microseconds(-1));
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EXPECT_THAT(select(1, nullptr, nullptr, nullptr, &timeout),
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SyscallFailsWithErrno(EINVAL));
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// Ignore timeout as its value is now undefined.
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}
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// Verify that a signal interrupts select.
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//
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// If random S/R interrupts the select, SIGALRM may be delivered before select
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// restarts, causing the select to hang forever.
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TEST_F(SelectTest, InterruptedBySignal_NoRandomSave) {
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absl::Duration duration(absl::Seconds(5));
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struct timeval timeout = absl::ToTimeval(duration);
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SetTimer(absl::Milliseconds(100));
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ASSERT_FALSE(TimerFired());
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ASSERT_THAT(select(1, nullptr, nullptr, nullptr, &timeout),
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SyscallFailsWithErrno(EINTR));
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EXPECT_TRUE(TimerFired());
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// Ignore timeout as its value is now undefined.
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}
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TEST_F(SelectTest, IgnoreBitsAboveNfds) {
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// fd_set is a bit array with at least FD_SETSIZE bits. Test that bits
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// corresponding to file descriptors above nfds are ignored.
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fd_set read_set;
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FD_ZERO(&read_set);
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constexpr int kNfds = 1;
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for (int fd = kNfds; fd < FD_SETSIZE; fd++) {
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FD_SET(fd, &read_set);
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}
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// Pass a zero timeout so that select returns immediately.
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struct timeval timeout = {};
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EXPECT_THAT(select(kNfds, &read_set, nullptr, nullptr, &timeout),
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SyscallSucceedsWithValue(0));
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}
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// This test illustrates Linux's behavior of 'select' calls passing after
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// setrlimit RLIMIT_NOFILE is called. In particular, versions of sshd rely on
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// this behavior.
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TEST_F(SelectTest, SetrlimitCallNOFILE) {
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fd_set read_set;
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FD_ZERO(&read_set);
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timeval timeout = {};
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const FileDescriptor fd = ASSERT_NO_ERRNO_AND_VALUE(
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Open(NewTempAbsPath(), O_RDONLY | O_CREAT, S_IRUSR));
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Cleanup reset_rlimit =
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ASSERT_NO_ERRNO_AND_VALUE(ScopedSetSoftRlimit(RLIMIT_NOFILE, 0));
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FD_SET(fd.get(), &read_set);
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// this call with zero timeout should return immediately
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EXPECT_THAT(select(fd.get() + 1, &read_set, nullptr, nullptr, &timeout),
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SyscallSucceeds());
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}
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} // namespace
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} // namespace testing
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} // namespace gvisor
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