gvisor/test/syscalls/linux/exit.cc

// 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/flags/flag.h"
#include "absl/time/time.h"
#include "test/util/file_descriptor.h"
#include "test/util/multiprocess_util.h"
#include "test/util/test_util.h"
#include "test/util/thread_util.h"
#include "test/util/time_util.h"

ABSL_FLAG(bool, test_child, false,
          "If true, run the ExitAllThreads child workload.");

namespace gvisor {
namespace testing {

namespace {

void TestExit(int code) {
  pid_t pid = fork();
  if (pid == 0) {
    _exit(code);
  }

  ASSERT_THAT(pid, SyscallSucceeds());

  int status;
  EXPECT_THAT(RetryEINTR(waitpid)(pid, &status, 0), SyscallSucceeds());
  EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == code) << status;
}

TEST(ExitTest, Success) { TestExit(0); }

TEST(ExitTest, Failure) { TestExit(1); }

// This test ensures that a process's file descriptors are closed when it calls
// exit(). In order to test this, the parent tries to read from a pipe whose
// write end is held by the child. While the read is blocking, the child exits,
// which should cause the parent to read 0 bytes due to EOF.
TEST(ExitTest, CloseFds) {
  int pipe_fds[2];
  ASSERT_THAT(pipe(pipe_fds), SyscallSucceeds());

  FileDescriptor read_fd(pipe_fds[0]);
  FileDescriptor write_fd(pipe_fds[1]);

  pid_t pid = fork();
  if (pid == 0) {
    read_fd.reset();

    SleepSafe(absl::Seconds(10));

    _exit(0);
  }

  EXPECT_THAT(pid, SyscallSucceeds());

  write_fd.reset();

  char buf[10];
  EXPECT_THAT(ReadFd(read_fd.get(), buf, sizeof(buf)),
              SyscallSucceedsWithValue(0));
}

TEST(ExitTest, ExitAllThreads) {
  pid_t child_pid = -1;
  int execve_errno = 0;
  auto cleanup = ASSERT_NO_ERRNO_AND_VALUE(
      ForkAndExec("/proc/self/exe", {"/proc/self/exe", "--test_child"}, {},
                  nullptr, &child_pid, &execve_errno));
  ASSERT_GT(child_pid, 0);
  ASSERT_EQ(execve_errno, 0);

  int status;
  EXPECT_THAT(RetryEINTR(waitpid)(child_pid, &status, 0), SyscallSucceeds());
  EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0) << status;
}

void RunChild() {
  ScopedThread t([] { _exit(0); });
  t.Join();
  // Should not be reached
  abort();
}

// SIGKILL of zombied thread group does not change exit status.
TEST(ExitTest, SigkillZombieGroup) {
  int pipe_fds[2];
  ASSERT_THAT(pipe(pipe_fds), SyscallSucceeds());

  FileDescriptor read_fd(pipe_fds[0]);
  FileDescriptor write_fd(pipe_fds[1]);

  pid_t pid = fork();
  if (pid == 0) {
    read_fd.reset();

    _exit(0);
  }

  EXPECT_THAT(pid, SyscallSucceeds());
  write_fd.reset();

  // Wait for pipe to automatically close to indicate that the child is zombied.
  char buf[10];
  EXPECT_THAT(ReadFd(read_fd.get(), buf, sizeof(buf)),
              SyscallSucceedsWithValue(0));

  EXPECT_THAT(kill(pid, SIGKILL), SyscallSucceeds());

  // SIGKILL did not change exit status.
  int status;
  EXPECT_THAT(RetryEINTR(waitpid)(pid, &status, 0), SyscallSucceeds());
  EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0) << status;
}

// Variant of SigkillZombieGroup using exit(2) instead of exit_group(2).
TEST(ExitTest, SigkillZombieThread) {
  int pipe_fds[2];
  ASSERT_THAT(pipe(pipe_fds), SyscallSucceeds());

  FileDescriptor read_fd(pipe_fds[0]);
  FileDescriptor write_fd(pipe_fds[1]);

  pid_t pid = fork();
  if (pid == 0) {
    read_fd.reset();

    syscall(SYS_exit, 0);
  }

  EXPECT_THAT(pid, SyscallSucceeds());
  write_fd.reset();

  // Wait for pipe to automatically close to indicate that the child is zombied.
  char buf[10];
  EXPECT_THAT(ReadFd(read_fd.get(), buf, sizeof(buf)),
              SyscallSucceedsWithValue(0));

  EXPECT_THAT(kill(pid, SIGKILL), SyscallSucceeds());

  // SIGKILL did not change exit status.
  int status;
  EXPECT_THAT(RetryEINTR(waitpid)(pid, &status, 0), SyscallSucceeds());
  EXPECT_TRUE(WIFEXITED(status) && WEXITSTATUS(status) == 0) << status;
}

}  // namespace

}  // namespace testing
}  // namespace gvisor

int main(int argc, char** argv) {
  gvisor::testing::TestInit(&argc, &argv);

  if (absl::GetFlag(FLAGS_test_child)) {
    gvisor::testing::RunChild();
    return 1;
  }

  return gvisor::testing::RunAllTests();
}