1 files changed, 323 insertions, 0 deletions
diff --git a/test/syscalls/linux/sigtimedwait.cc b/test/syscalls/linux/sigtimedwait.cc
new file mode 100644
index 000000000..4f8afff15
--- /dev/null
+++ b/test/syscalls/linux/sigtimedwait.cc
@@ -0,0 +1,323 @@
+// 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 <sys/wait.h>
+#include <unistd.h>
+
+#include "gtest/gtest.h"
+#include "absl/time/clock.h"
+#include "absl/time/time.h"
+#include "test/util/file_descriptor.h"
+#include "test/util/logging.h"
+#include "test/util/signal_util.h"
+#include "test/util/test_util.h"
+#include "test/util/thread_util.h"
+#include "test/util/timer_util.h"
+
+namespace gvisor {
+namespace testing {
+
+namespace {
+
+// N.B. main() blocks SIGALRM and SIGCHLD on all threads.
+
+constexpr int kAlarmSecs = 12;
+
+void NoopHandler(int sig, siginfo_t* info, void* context) {}
+
+TEST(SigtimedwaitTest, InvalidTimeout) {
+  sigset_t mask;
+  sigemptyset(&mask);
+  struct timespec timeout = {0, 1000000001};
+  EXPECT_THAT(sigtimedwait(&mask, nullptr, &timeout),
+              SyscallFailsWithErrno(EINVAL));
+  timeout = {-1, 0};
+  EXPECT_THAT(sigtimedwait(&mask, nullptr, &timeout),
+              SyscallFailsWithErrno(EINVAL));
+  timeout = {0, -1};
+  EXPECT_THAT(sigtimedwait(&mask, nullptr, &timeout),
+              SyscallFailsWithErrno(EINVAL));
+}
+
+// No random save as the test relies on alarm timing. Cooperative save tests
+// already cover the save between alarm and wait.
+TEST(SigtimedwaitTest, AlarmReturnsAlarm_NoRandomSave) {
+  struct itimerval itv = {};
+  itv.it_value.tv_sec = kAlarmSecs;
+  const auto itimer_cleanup =
+      ASSERT_NO_ERRNO_AND_VALUE(ScopedItimer(ITIMER_REAL, itv));
+
+  sigset_t mask;
+  sigemptyset(&mask);
+  sigaddset(&mask, SIGALRM);
+  siginfo_t info = {};
+  EXPECT_THAT(RetryEINTR(sigtimedwait)(&mask, &info, nullptr),
+              SyscallSucceedsWithValue(SIGALRM));
+  EXPECT_EQ(SIGALRM, info.si_signo);
+}
+
+// No random save as the test relies on alarm timing. Cooperative save tests
+// already cover the save between alarm and wait.
+TEST(SigtimedwaitTest, NullTimeoutReturnsEINTR_NoRandomSave) {
+  struct sigaction sa;
+  sa.sa_sigaction = NoopHandler;
+  sigfillset(&sa.sa_mask);
+  sa.sa_flags = SA_SIGINFO;
+  const auto action_cleanup =
+      ASSERT_NO_ERRNO_AND_VALUE(ScopedSigaction(SIGALRM, sa));
+
+  const auto mask_cleanup =
+      ASSERT_NO_ERRNO_AND_VALUE(ScopedSignalMask(SIG_UNBLOCK, SIGALRM));
+
+  struct itimerval itv = {};
+  itv.it_value.tv_sec = kAlarmSecs;
+  const auto itimer_cleanup =
+      ASSERT_NO_ERRNO_AND_VALUE(ScopedItimer(ITIMER_REAL, itv));
+
+  sigset_t mask;
+  sigemptyset(&mask);
+  EXPECT_THAT(sigtimedwait(&mask, nullptr, nullptr),
+              SyscallFailsWithErrno(EINTR));
+}
+
+TEST(SigtimedwaitTest, LegitTimeoutReturnsEAGAIN) {
+  sigset_t mask;
+  sigemptyset(&mask);
+  struct timespec timeout = {1, 0};  // 1 second
+  EXPECT_THAT(RetryEINTR(sigtimedwait)(&mask, nullptr, &timeout),
+              SyscallFailsWithErrno(EAGAIN));
+}
+
+TEST(SigtimedwaitTest, ZeroTimeoutReturnsEAGAIN) {
+  sigset_t mask;
+  sigemptyset(&mask);
+  struct timespec timeout = {0, 0};  // 0 second
+  EXPECT_THAT(sigtimedwait(&mask, nullptr, &timeout),
+              SyscallFailsWithErrno(EAGAIN));
+}
+
+TEST(SigtimedwaitTest, KillGeneratedSIGCHLD) {
+  EXPECT_THAT(kill(getpid(), SIGCHLD), SyscallSucceeds());
+
+  sigset_t mask;
+  sigemptyset(&mask);
+  sigaddset(&mask, SIGCHLD);
+  struct timespec ts = {5, 0};
+  EXPECT_THAT(RetryEINTR(sigtimedwait)(&mask, nullptr, &ts),
+              SyscallSucceedsWithValue(SIGCHLD));
+}
+
+TEST(SigtimedwaitTest, ChildExitGeneratedSIGCHLD) {
+  pid_t pid = fork();
+  if (pid == 0) {
+    _exit(0);
+  }
+  ASSERT_THAT(pid, SyscallSucceeds());
+
+  int status;
+  EXPECT_THAT(waitpid(pid, &status, 0), SyscallSucceedsWithValue(pid));
+  EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0) << status;
+
+  sigset_t mask;
+  sigemptyset(&mask);
+  sigaddset(&mask, SIGCHLD);
+  struct timespec ts = {5, 0};
+  EXPECT_THAT(RetryEINTR(sigtimedwait)(&mask, nullptr, &ts),
+              SyscallSucceedsWithValue(SIGCHLD));
+}
+
+TEST(SigtimedwaitTest, ChildExitGeneratedSIGCHLDWithHandler) {
+  // Setup handler for SIGCHLD, but don't unblock it.
+  struct sigaction sa;
+  sa.sa_sigaction = NoopHandler;
+  sigfillset(&sa.sa_mask);
+  sa.sa_flags = SA_SIGINFO;
+  const auto action_cleanup =
+      ASSERT_NO_ERRNO_AND_VALUE(ScopedSigaction(SIGCHLD, sa));
+
+  pid_t pid = fork();
+  if (pid == 0) {
+    _exit(0);
+  }
+  ASSERT_THAT(pid, SyscallSucceeds());
+
+  sigset_t mask;
+  sigemptyset(&mask);
+  sigaddset(&mask, SIGCHLD);
+  struct timespec ts = {5, 0};
+  EXPECT_THAT(RetryEINTR(sigtimedwait)(&mask, nullptr, &ts),
+              SyscallSucceedsWithValue(SIGCHLD));
+
+  int status;
+  EXPECT_THAT(waitpid(pid, &status, 0), SyscallSucceedsWithValue(pid));
+  EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0) << status;
+}
+
+// sigtimedwait cannot catch SIGKILL.
+TEST(SigtimedwaitTest, SIGKILLUncaught) {
+  // This is a regression test for sigtimedwait dequeuing SIGKILLs, thus
+  // preventing the task from exiting.
+  //
+  // The explanation below is specific to behavior in gVisor. The Linux behavior
+  // here is irrelevant because without a bug that prevents delivery of SIGKILL,
+  // none of this behavior is visible (in Linux or gVisor).
+  //
+  // SIGKILL is rather intrusive. Simply sending the SIGKILL marks
+  // ThreadGroup.exitStatus as exiting with SIGKILL, before the SIGKILL is even
+  // delivered.
+  //
+  // As a result, we cannot simply exit the child with a different exit code if
+  // it survives and expect to see that code in waitpid because:
+  //   1. PrepareGroupExit will override Task.exitStatus with
+  //      ThreadGroup.exitStatus.
+  //   2. waitpid(2) will always return ThreadGroup.exitStatus rather than
+  //      Task.exitStatus.
+  //
+  // We could use exit(2) to set Task.exitStatus without override, and a SIGCHLD
+  // handler to receive Task.exitStatus in the parent, but with that much
+  // test complexity, it is cleaner to simply use a pipe to notify the parent
+  // that we survived.
+  constexpr auto kSigtimedwaitSetupTime = absl::Seconds(2);
+
+  int pipe_fds[2];
+  ASSERT_THAT(pipe(pipe_fds), SyscallSucceeds());
+  FileDescriptor rfd(pipe_fds[0]);
+  FileDescriptor wfd(pipe_fds[1]);
+
+  pid_t pid = fork();
+  if (pid == 0) {
+    rfd.reset();
+
+    sigset_t mask;
+    sigemptyset(&mask);
+    sigaddset(&mask, SIGKILL);
+    RetryEINTR(sigtimedwait)(&mask, nullptr, nullptr);
+
+    // Survived.
+    char c = 'a';
+    TEST_PCHECK(WriteFd(wfd.get(), &c, 1) == 1);
+    _exit(1);
+  }
+  ASSERT_THAT(pid, SyscallSucceeds());
+
+  wfd.reset();
+
+  // Wait for child to block in sigtimedwait, then kill it.
+  absl::SleepFor(kSigtimedwaitSetupTime);
+
+  // Sending SIGKILL will attempt to enqueue the signal twice: once in the
+  // normal signal sending path, and once to all Tasks in the ThreadGroup when
+  // applying SIGKILL side-effects.
+  //
+  // If we use kill(2), the former will be on the ThreadGroup signal queue and
+  // the latter will be on the Task signal queue. sigtimedwait can only dequeue
+  // one signal, so the other would kill the Task, masking bugs.
+  //
+  // If we use tkill(2), the former will be on the Task signal queue and the
+  // latter will be dropped as a duplicate. Then sigtimedwait can theoretically
+  // dequeue the single SIGKILL.
+  EXPECT_THAT(syscall(SYS_tkill, pid, SIGKILL), SyscallSucceeds());
+
+  int status;
+  EXPECT_THAT(RetryEINTR(waitpid)(pid, &status, 0),
+              SyscallSucceedsWithValue(pid));
+  EXPECT_TRUE(WIFSIGNALED(status) && WTERMSIG(status) == SIGKILL) << status;
+
+  // Child shouldn't have survived.
+  char c;
+  EXPECT_THAT(ReadFd(rfd.get(), &c, 1), SyscallSucceedsWithValue(0));
+}
+
+TEST(SigtimedwaitTest, IgnoredUnmaskedSignal) {
+  constexpr int kSigno = SIGUSR1;
+  constexpr auto kSigtimedwaitSetupTime = absl::Seconds(2);
+  constexpr auto kSigtimedwaitTimeout = absl::Seconds(5);
+  ASSERT_GT(kSigtimedwaitTimeout, kSigtimedwaitSetupTime);
+
+  // Ensure that kSigno is ignored, and unmasked on this thread.
+  struct sigaction sa = {};
+  sa.sa_handler = SIG_IGN;
+  const auto scoped_sigaction =
+      ASSERT_NO_ERRNO_AND_VALUE(ScopedSigaction(kSigno, sa));
+  sigset_t mask;
+  sigemptyset(&mask);
+  sigaddset(&mask, kSigno);
+  auto scoped_sigmask =
+      ASSERT_NO_ERRNO_AND_VALUE(ScopedSignalMask(SIG_UNBLOCK, mask));
+
+  // Create a thread which will send us kSigno while we are blocked in
+  // sigtimedwait.
+  pid_t tid = gettid();
+  ScopedThread sigthread([&] {
+    absl::SleepFor(kSigtimedwaitSetupTime);
+    EXPECT_THAT(tgkill(getpid(), tid, kSigno), SyscallSucceeds());
+  });
+
+  // sigtimedwait should not observe kSigno since it is ignored and already
+  // unmasked, causing it to be dropped before it is enqueued.
+  struct timespec timeout_ts = absl::ToTimespec(kSigtimedwaitTimeout);
+  EXPECT_THAT(RetryEINTR(sigtimedwait)(&mask, nullptr, &timeout_ts),
+              SyscallFailsWithErrno(EAGAIN));
+}
+
+TEST(SigtimedwaitTest, IgnoredMaskedSignal) {
+  constexpr int kSigno = SIGUSR1;
+  constexpr auto kSigtimedwaitSetupTime = absl::Seconds(2);
+  constexpr auto kSigtimedwaitTimeout = absl::Seconds(5);
+  ASSERT_GT(kSigtimedwaitTimeout, kSigtimedwaitSetupTime);
+
+  // Ensure that kSigno is ignored, and masked on this thread.
+  struct sigaction sa = {};
+  sa.sa_handler = SIG_IGN;
+  const auto scoped_sigaction =
+      ASSERT_NO_ERRNO_AND_VALUE(ScopedSigaction(kSigno, sa));
+  sigset_t mask;
+  sigemptyset(&mask);
+  sigaddset(&mask, kSigno);
+  auto scoped_sigmask =
+      ASSERT_NO_ERRNO_AND_VALUE(ScopedSignalMask(SIG_BLOCK, mask));
+
+  // Create a thread which will send us kSigno while we are blocked in
+  // sigtimedwait.
+  pid_t tid = gettid();
+  ScopedThread sigthread([&] {
+    absl::SleepFor(kSigtimedwaitSetupTime);
+    EXPECT_THAT(tgkill(getpid(), tid, kSigno), SyscallSucceeds());
+  });
+
+  // sigtimedwait should observe kSigno since it is normally masked, causing it
+  // to be enqueued despite being ignored.
+  struct timespec timeout_ts = absl::ToTimespec(kSigtimedwaitTimeout);
+  EXPECT_THAT(RetryEINTR(sigtimedwait)(&mask, nullptr, &timeout_ts),
+              SyscallSucceedsWithValue(kSigno));
+}
+
+}  // namespace
+
+}  // namespace testing
+}  // namespace gvisor
+
+int main(int argc, char** argv) {
+  // These tests depend on delivering SIGALRM/SIGCHLD to the main thread or in
+  // sigtimedwait. Block them so that any other threads created by TestInit will
+  // also have them blocked.
+  sigset_t set;
+  sigemptyset(&set);
+  sigaddset(&set, SIGALRM);
+  sigaddset(&set, SIGCHLD);
+  TEST_PCHECK(sigprocmask(SIG_BLOCK, &set, nullptr) == 0);
+
+  gvisor::testing::TestInit(&argc, &argv);
+  return gvisor::testing::RunAllTests();
+}