324 lines
11 KiB
C++
324 lines
11 KiB
C++
// Copyright 2018 The gVisor Authors.
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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 <sys/wait.h>
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#include <unistd.h>
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#include "gtest/gtest.h"
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#include "absl/time/clock.h"
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#include "absl/time/time.h"
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#include "test/util/file_descriptor.h"
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#include "test/util/logging.h"
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#include "test/util/signal_util.h"
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#include "test/util/test_util.h"
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#include "test/util/thread_util.h"
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#include "test/util/timer_util.h"
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namespace gvisor {
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namespace testing {
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namespace {
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// N.B. main() blocks SIGALRM and SIGCHLD on all threads.
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constexpr int kAlarmSecs = 12;
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void NoopHandler(int sig, siginfo_t* info, void* context) {}
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TEST(SigtimedwaitTest, InvalidTimeout) {
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sigset_t mask;
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sigemptyset(&mask);
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struct timespec timeout = {0, 1000000001};
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EXPECT_THAT(sigtimedwait(&mask, nullptr, &timeout),
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SyscallFailsWithErrno(EINVAL));
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timeout = {-1, 0};
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EXPECT_THAT(sigtimedwait(&mask, nullptr, &timeout),
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SyscallFailsWithErrno(EINVAL));
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timeout = {0, -1};
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EXPECT_THAT(sigtimedwait(&mask, nullptr, &timeout),
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SyscallFailsWithErrno(EINVAL));
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}
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// No random save as the test relies on alarm timing. Cooperative save tests
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// already cover the save between alarm and wait.
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TEST(SigtimedwaitTest, AlarmReturnsAlarm_NoRandomSave) {
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struct itimerval itv = {};
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itv.it_value.tv_sec = kAlarmSecs;
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const auto itimer_cleanup =
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ASSERT_NO_ERRNO_AND_VALUE(ScopedItimer(ITIMER_REAL, itv));
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sigset_t mask;
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sigemptyset(&mask);
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sigaddset(&mask, SIGALRM);
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siginfo_t info = {};
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EXPECT_THAT(RetryEINTR(sigtimedwait)(&mask, &info, nullptr),
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SyscallSucceedsWithValue(SIGALRM));
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EXPECT_EQ(SIGALRM, info.si_signo);
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}
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// No random save as the test relies on alarm timing. Cooperative save tests
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// already cover the save between alarm and wait.
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TEST(SigtimedwaitTest, NullTimeoutReturnsEINTR_NoRandomSave) {
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struct sigaction sa;
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sa.sa_sigaction = NoopHandler;
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sigfillset(&sa.sa_mask);
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sa.sa_flags = SA_SIGINFO;
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const auto action_cleanup =
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ASSERT_NO_ERRNO_AND_VALUE(ScopedSigaction(SIGALRM, sa));
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const auto mask_cleanup =
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ASSERT_NO_ERRNO_AND_VALUE(ScopedSignalMask(SIG_UNBLOCK, SIGALRM));
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struct itimerval itv = {};
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itv.it_value.tv_sec = kAlarmSecs;
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const auto itimer_cleanup =
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ASSERT_NO_ERRNO_AND_VALUE(ScopedItimer(ITIMER_REAL, itv));
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sigset_t mask;
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sigemptyset(&mask);
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EXPECT_THAT(sigtimedwait(&mask, nullptr, nullptr),
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SyscallFailsWithErrno(EINTR));
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}
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TEST(SigtimedwaitTest, LegitTimeoutReturnsEAGAIN) {
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sigset_t mask;
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sigemptyset(&mask);
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struct timespec timeout = {1, 0}; // 1 second
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EXPECT_THAT(RetryEINTR(sigtimedwait)(&mask, nullptr, &timeout),
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SyscallFailsWithErrno(EAGAIN));
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}
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TEST(SigtimedwaitTest, ZeroTimeoutReturnsEAGAIN) {
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sigset_t mask;
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sigemptyset(&mask);
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struct timespec timeout = {0, 0}; // 0 second
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EXPECT_THAT(sigtimedwait(&mask, nullptr, &timeout),
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SyscallFailsWithErrno(EAGAIN));
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}
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TEST(SigtimedwaitTest, KillGeneratedSIGCHLD) {
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EXPECT_THAT(kill(getpid(), SIGCHLD), SyscallSucceeds());
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sigset_t mask;
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sigemptyset(&mask);
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sigaddset(&mask, SIGCHLD);
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struct timespec ts = {5, 0};
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EXPECT_THAT(RetryEINTR(sigtimedwait)(&mask, nullptr, &ts),
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SyscallSucceedsWithValue(SIGCHLD));
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}
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TEST(SigtimedwaitTest, ChildExitGeneratedSIGCHLD) {
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pid_t pid = fork();
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if (pid == 0) {
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_exit(0);
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}
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ASSERT_THAT(pid, SyscallSucceeds());
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int status;
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EXPECT_THAT(waitpid(pid, &status, 0), SyscallSucceedsWithValue(pid));
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EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0) << status;
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sigset_t mask;
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sigemptyset(&mask);
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sigaddset(&mask, SIGCHLD);
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struct timespec ts = {5, 0};
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EXPECT_THAT(RetryEINTR(sigtimedwait)(&mask, nullptr, &ts),
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SyscallSucceedsWithValue(SIGCHLD));
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}
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TEST(SigtimedwaitTest, ChildExitGeneratedSIGCHLDWithHandler) {
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// Setup handler for SIGCHLD, but don't unblock it.
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struct sigaction sa;
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sa.sa_sigaction = NoopHandler;
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sigfillset(&sa.sa_mask);
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sa.sa_flags = SA_SIGINFO;
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const auto action_cleanup =
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ASSERT_NO_ERRNO_AND_VALUE(ScopedSigaction(SIGCHLD, sa));
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pid_t pid = fork();
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if (pid == 0) {
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_exit(0);
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}
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ASSERT_THAT(pid, SyscallSucceeds());
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sigset_t mask;
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sigemptyset(&mask);
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sigaddset(&mask, SIGCHLD);
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struct timespec ts = {5, 0};
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EXPECT_THAT(RetryEINTR(sigtimedwait)(&mask, nullptr, &ts),
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SyscallSucceedsWithValue(SIGCHLD));
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int status;
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EXPECT_THAT(waitpid(pid, &status, 0), SyscallSucceedsWithValue(pid));
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EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0) << status;
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}
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// sigtimedwait cannot catch SIGKILL.
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TEST(SigtimedwaitTest, SIGKILLUncaught) {
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// This is a regression test for sigtimedwait dequeuing SIGKILLs, thus
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// preventing the task from exiting.
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//
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// The explanation below is specific to behavior in gVisor. The Linux behavior
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// here is irrelevant because without a bug that prevents delivery of SIGKILL,
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// none of this behavior is visible (in Linux or gVisor).
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//
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// SIGKILL is rather intrusive. Simply sending the SIGKILL marks
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// ThreadGroup.exitStatus as exiting with SIGKILL, before the SIGKILL is even
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// delivered.
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//
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// As a result, we cannot simply exit the child with a different exit code if
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// it survives and expect to see that code in waitpid because:
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// 1. PrepareGroupExit will override Task.exitStatus with
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// ThreadGroup.exitStatus.
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// 2. waitpid(2) will always return ThreadGroup.exitStatus rather than
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// Task.exitStatus.
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//
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// We could use exit(2) to set Task.exitStatus without override, and a SIGCHLD
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// handler to receive Task.exitStatus in the parent, but with that much
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// test complexity, it is cleaner to simply use a pipe to notify the parent
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// that we survived.
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constexpr auto kSigtimedwaitSetupTime = absl::Seconds(2);
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int pipe_fds[2];
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ASSERT_THAT(pipe(pipe_fds), SyscallSucceeds());
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FileDescriptor rfd(pipe_fds[0]);
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FileDescriptor wfd(pipe_fds[1]);
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pid_t pid = fork();
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if (pid == 0) {
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rfd.reset();
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sigset_t mask;
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sigemptyset(&mask);
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sigaddset(&mask, SIGKILL);
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RetryEINTR(sigtimedwait)(&mask, nullptr, nullptr);
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// Survived.
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char c = 'a';
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TEST_PCHECK(WriteFd(wfd.get(), &c, 1) == 1);
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_exit(1);
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}
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ASSERT_THAT(pid, SyscallSucceeds());
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wfd.reset();
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// Wait for child to block in sigtimedwait, then kill it.
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absl::SleepFor(kSigtimedwaitSetupTime);
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// Sending SIGKILL will attempt to enqueue the signal twice: once in the
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// normal signal sending path, and once to all Tasks in the ThreadGroup when
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// applying SIGKILL side-effects.
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//
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// If we use kill(2), the former will be on the ThreadGroup signal queue and
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// the latter will be on the Task signal queue. sigtimedwait can only dequeue
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// one signal, so the other would kill the Task, masking bugs.
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//
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// If we use tkill(2), the former will be on the Task signal queue and the
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// latter will be dropped as a duplicate. Then sigtimedwait can theoretically
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// dequeue the single SIGKILL.
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EXPECT_THAT(syscall(SYS_tkill, pid, SIGKILL), SyscallSucceeds());
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int status;
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EXPECT_THAT(RetryEINTR(waitpid)(pid, &status, 0),
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SyscallSucceedsWithValue(pid));
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EXPECT_TRUE(WIFSIGNALED(status) && WTERMSIG(status) == SIGKILL) << status;
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// Child shouldn't have survived.
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char c;
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EXPECT_THAT(ReadFd(rfd.get(), &c, 1), SyscallSucceedsWithValue(0));
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}
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TEST(SigtimedwaitTest, IgnoredUnmaskedSignal) {
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constexpr int kSigno = SIGUSR1;
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constexpr auto kSigtimedwaitSetupTime = absl::Seconds(2);
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constexpr auto kSigtimedwaitTimeout = absl::Seconds(5);
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ASSERT_GT(kSigtimedwaitTimeout, kSigtimedwaitSetupTime);
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// Ensure that kSigno is ignored, and unmasked on this thread.
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struct sigaction sa = {};
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sa.sa_handler = SIG_IGN;
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const auto scoped_sigaction =
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ASSERT_NO_ERRNO_AND_VALUE(ScopedSigaction(kSigno, sa));
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sigset_t mask;
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sigemptyset(&mask);
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sigaddset(&mask, kSigno);
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auto scoped_sigmask =
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ASSERT_NO_ERRNO_AND_VALUE(ScopedSignalMask(SIG_UNBLOCK, mask));
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// Create a thread which will send us kSigno while we are blocked in
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// sigtimedwait.
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pid_t tid = gettid();
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ScopedThread sigthread([&] {
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absl::SleepFor(kSigtimedwaitSetupTime);
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EXPECT_THAT(tgkill(getpid(), tid, kSigno), SyscallSucceeds());
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});
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// sigtimedwait should not observe kSigno since it is ignored and already
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// unmasked, causing it to be dropped before it is enqueued.
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struct timespec timeout_ts = absl::ToTimespec(kSigtimedwaitTimeout);
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EXPECT_THAT(RetryEINTR(sigtimedwait)(&mask, nullptr, &timeout_ts),
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SyscallFailsWithErrno(EAGAIN));
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}
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TEST(SigtimedwaitTest, IgnoredMaskedSignal) {
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constexpr int kSigno = SIGUSR1;
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constexpr auto kSigtimedwaitSetupTime = absl::Seconds(2);
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constexpr auto kSigtimedwaitTimeout = absl::Seconds(5);
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ASSERT_GT(kSigtimedwaitTimeout, kSigtimedwaitSetupTime);
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// Ensure that kSigno is ignored, and masked on this thread.
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struct sigaction sa = {};
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sa.sa_handler = SIG_IGN;
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const auto scoped_sigaction =
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ASSERT_NO_ERRNO_AND_VALUE(ScopedSigaction(kSigno, sa));
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sigset_t mask;
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sigemptyset(&mask);
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sigaddset(&mask, kSigno);
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auto scoped_sigmask =
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ASSERT_NO_ERRNO_AND_VALUE(ScopedSignalMask(SIG_BLOCK, mask));
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// Create a thread which will send us kSigno while we are blocked in
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// sigtimedwait.
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pid_t tid = gettid();
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ScopedThread sigthread([&] {
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absl::SleepFor(kSigtimedwaitSetupTime);
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EXPECT_THAT(tgkill(getpid(), tid, kSigno), SyscallSucceeds());
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});
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// sigtimedwait should observe kSigno since it is normally masked, causing it
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// to be enqueued despite being ignored.
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struct timespec timeout_ts = absl::ToTimespec(kSigtimedwaitTimeout);
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EXPECT_THAT(RetryEINTR(sigtimedwait)(&mask, nullptr, &timeout_ts),
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SyscallSucceedsWithValue(kSigno));
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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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int main(int argc, char** argv) {
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// These tests depend on delivering SIGALRM/SIGCHLD to the main thread or in
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// sigtimedwait. Block them so that any other threads created by TestInit will
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// also have them blocked.
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sigset_t set;
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sigemptyset(&set);
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sigaddset(&set, SIGALRM);
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sigaddset(&set, SIGCHLD);
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TEST_PCHECK(sigprocmask(SIG_BLOCK, &set, nullptr) == 0);
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gvisor::testing::TestInit(&argc, &argv);
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return gvisor::testing::RunAllTests();
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}
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