1 files changed, 190 insertions, 0 deletions
diff --git a/test/syscalls/linux/pselect.cc b/test/syscalls/linux/pselect.cc
new file mode 100644
index 000000000..3294f6c14
--- /dev/null
+++ b/test/syscalls/linux/pselect.cc
@@ -0,0 +1,190 @@
+// Copyright 2018 Google LLC
+//
+// 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 <signal.h>
+#include <sys/select.h>
+
+#include "gtest/gtest.h"
+#include "absl/time/time.h"
+#include "test/syscalls/linux/base_poll_test.h"
+#include "test/util/signal_util.h"
+#include "test/util/test_util.h"
+
+namespace gvisor {
+namespace testing {
+namespace {
+
+struct MaskWithSize {
+  sigset_t* mask;
+  size_t mask_size;
+};
+
+// Linux and glibc have a different idea of the sizeof sigset_t. When calling
+// the syscall directly, use what the kernel expects.
+unsigned kSigsetSize = SIGRTMAX / 8;
+
+// Linux pselect(2) differs from the glibc wrapper function in that Linux
+// updates the timeout with the amount of time remaining. In order to test this
+// behavior we need to use the syscall directly.
+int syscallPselect6(int nfds, fd_set* readfds, fd_set* writefds,
+                    fd_set* exceptfds, struct timespec* timeout,
+                    const MaskWithSize* mask_with_size) {
+  return syscall(SYS_pselect6, nfds, readfds, writefds, exceptfds, timeout,
+                 mask_with_size);
+}
+
+class PselectTest : public BasePollTest {
+ protected:
+  void SetUp() override { BasePollTest::SetUp(); }
+  void TearDown() override { BasePollTest::TearDown(); }
+};
+
+// See that when there are no FD sets, pselect behaves like sleep.
+TEST_F(PselectTest, NullFds) {
+  struct timespec timeout = absl::ToTimespec(absl::Milliseconds(10));
+  ASSERT_THAT(syscallPselect6(0, nullptr, nullptr, nullptr, &timeout, nullptr),
+              SyscallSucceeds());
+  EXPECT_EQ(timeout.tv_sec, 0);
+  EXPECT_EQ(timeout.tv_nsec, 0);
+
+  timeout = absl::ToTimespec(absl::Milliseconds(10));
+  ASSERT_THAT(syscallPselect6(1, nullptr, nullptr, nullptr, &timeout, nullptr),
+              SyscallSucceeds());
+  EXPECT_EQ(timeout.tv_sec, 0);
+  EXPECT_EQ(timeout.tv_nsec, 0);
+}
+
+TEST_F(PselectTest, ClosedFds) {
+  fd_set read_set;
+  FD_ZERO(&read_set);
+  int fd;
+  ASSERT_THAT(fd = dup(1), SyscallSucceeds());
+  ASSERT_THAT(close(fd), SyscallSucceeds());
+  FD_SET(fd, &read_set);
+  struct timespec timeout = absl::ToTimespec(absl::Milliseconds(10));
+  EXPECT_THAT(
+      syscallPselect6(fd + 1, &read_set, nullptr, nullptr, &timeout, nullptr),
+      SyscallFailsWithErrno(EBADF));
+}
+
+TEST_F(PselectTest, ZeroTimeout) {
+  struct timespec timeout = {};
+  ASSERT_THAT(syscallPselect6(1, nullptr, nullptr, nullptr, &timeout, nullptr),
+              SyscallSucceeds());
+  EXPECT_EQ(timeout.tv_sec, 0);
+  EXPECT_EQ(timeout.tv_nsec, 0);
+}
+
+// If random S/R interrupts the pselect, SIGALRM may be delivered before pselect
+// restarts, causing the pselect to hang forever.
+TEST_F(PselectTest, NoTimeout_NoRandomSave) {
+  // When there's no timeout, pselect may never return so set a timer.
+  SetTimer(absl::Milliseconds(100));
+  // See that we get interrupted by the timer.
+  ASSERT_THAT(syscallPselect6(1, nullptr, nullptr, nullptr, nullptr, nullptr),
+              SyscallFailsWithErrno(EINTR));
+  EXPECT_TRUE(TimerFired());
+}
+
+TEST_F(PselectTest, InvalidTimeoutNegative) {
+  struct timespec timeout = absl::ToTimespec(absl::Seconds(-1));
+  ASSERT_THAT(syscallPselect6(1, nullptr, nullptr, nullptr, &timeout, nullptr),
+              SyscallFailsWithErrno(EINVAL));
+  EXPECT_EQ(timeout.tv_sec, -1);
+  EXPECT_EQ(timeout.tv_nsec, 0);
+}
+
+TEST_F(PselectTest, InvalidTimeoutNotNormalized) {
+  struct timespec timeout = {0, 1000000001};
+  ASSERT_THAT(syscallPselect6(1, nullptr, nullptr, nullptr, &timeout, nullptr),
+              SyscallFailsWithErrno(EINVAL));
+  EXPECT_EQ(timeout.tv_sec, 0);
+  EXPECT_EQ(timeout.tv_nsec, 1000000001);
+}
+
+TEST_F(PselectTest, EmptySigMaskInvalidMaskSize) {
+  struct timespec timeout = {};
+  MaskWithSize invalid = {nullptr, 7};
+  EXPECT_THAT(syscallPselect6(0, nullptr, nullptr, nullptr, &timeout, &invalid),
+              SyscallSucceeds());
+}
+
+TEST_F(PselectTest, EmptySigMaskValidMaskSize) {
+  struct timespec timeout = {};
+  MaskWithSize invalid = {nullptr, 8};
+  EXPECT_THAT(syscallPselect6(0, nullptr, nullptr, nullptr, &timeout, &invalid),
+              SyscallSucceeds());
+}
+
+TEST_F(PselectTest, InvalidMaskSize) {
+  struct timespec timeout = {};
+  sigset_t sigmask;
+  ASSERT_THAT(sigemptyset(&sigmask), SyscallSucceeds());
+  MaskWithSize invalid = {&sigmask, 7};
+  EXPECT_THAT(syscallPselect6(1, nullptr, nullptr, nullptr, &timeout, &invalid),
+              SyscallFailsWithErrno(EINVAL));
+}
+
+// Verify that signals blocked by the pselect mask (that would otherwise be
+// allowed) do not interrupt pselect.
+TEST_F(PselectTest, SignalMaskBlocksSignal) {
+  absl::Duration duration(absl::Seconds(30));
+  struct timespec timeout = absl::ToTimespec(duration);
+  absl::Duration timer_duration(absl::Seconds(10));
+
+  // Call with a mask that blocks SIGALRM. See that pselect is not interrupted
+  // (i.e. returns 0) and that upon completion, the timer has fired.
+  sigset_t mask;
+  ASSERT_THAT(sigprocmask(0, nullptr, &mask), SyscallSucceeds());
+  ASSERT_THAT(sigaddset(&mask, SIGALRM), SyscallSucceeds());
+  MaskWithSize mask_with_size = {&mask, kSigsetSize};
+  SetTimer(timer_duration);
+  MaybeSave();
+  ASSERT_FALSE(TimerFired());
+  ASSERT_THAT(
+      syscallPselect6(1, nullptr, nullptr, nullptr, &timeout, &mask_with_size),
+      SyscallSucceeds());
+  EXPECT_TRUE(TimerFired());
+  EXPECT_EQ(absl::DurationFromTimespec(timeout), absl::Duration());
+}
+
+// Verify that signals allowed by the pselect mask (that would otherwise be
+// blocked) interrupt pselect.
+TEST_F(PselectTest, SignalMaskAllowsSignal) {
+  absl::Duration duration = absl::Seconds(30);
+  struct timespec timeout = absl::ToTimespec(duration);
+  absl::Duration timer_duration = absl::Seconds(10);
+
+  sigset_t mask;
+  ASSERT_THAT(sigprocmask(0, nullptr, &mask), SyscallSucceeds());
+
+  // Block SIGALRM.
+  auto cleanup =
+      ASSERT_NO_ERRNO_AND_VALUE(ScopedSignalMask(SIG_BLOCK, SIGALRM));
+
+  // Call with a mask that unblocks SIGALRM. See that pselect is interrupted.
+  MaskWithSize mask_with_size = {&mask, kSigsetSize};
+  SetTimer(timer_duration);
+  MaybeSave();
+  ASSERT_FALSE(TimerFired());
+  ASSERT_THAT(
+      syscallPselect6(1, nullptr, nullptr, nullptr, &timeout, &mask_with_size),
+      SyscallFailsWithErrno(EINTR));
+  EXPECT_TRUE(TimerFired());
+  EXPECT_GT(absl::DurationFromTimespec(timeout), absl::Duration());
+}
+
+}  // namespace
+}  // namespace testing
+}  // namespace gvisor