tests/signal_test.cpp

/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * 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 <errno.h>
#include <gtest/gtest.h>

#include "ScopedSignalHandler.h"

static size_t SIGNAL_MIN() {
  return 1; // Signals start at 1 (SIGHUP), not 0.
}

static size_t SIGNAL_MAX() {
  size_t result = SIGRTMAX;

#if defined(__BIONIC__) && !defined(__mips__) && !defined(__LP64__)
  // 32-bit bionic's sigset_t is too small for ARM and x86: 32 bits instead of 64.
  // This means you can't refer to any of the real-time signals.
  // See http://b/3038348 and http://b/5828899.
  result = 32;
#else
  // Otherwise, C libraries should be perfectly capable of using their largest signal.
  if (sizeof(sigset_t) * 8 < static_cast<size_t>(SIGRTMAX)) {
    abort();
  }
#endif

  return result;
}

template <typename Fn>
static void TestSigSet1(Fn fn) {
  // NULL sigset_t*.
  sigset_t* set_ptr = NULL;
  errno = 0;
  ASSERT_EQ(-1, fn(set_ptr));
  ASSERT_EQ(EINVAL, errno);

  // Non-NULL.
  sigset_t set;
  errno = 0;
  ASSERT_EQ(0, fn(&set));
  ASSERT_EQ(0, errno);
}

template <typename Fn>
static void TestSigSet2(Fn fn) {
  // NULL sigset_t*.
  sigset_t* set_ptr = NULL;
  errno = 0;
  ASSERT_EQ(-1, fn(set_ptr, SIGSEGV));
  ASSERT_EQ(EINVAL, errno);

  sigset_t set;
  sigemptyset(&set);

  // Bad signal number: too small.
  errno = 0;
  ASSERT_EQ(-1, fn(&set, 0));
  ASSERT_EQ(EINVAL, errno);

  // Bad signal number: too high.
  errno = 0;
  ASSERT_EQ(-1, fn(&set, SIGNAL_MAX() + 1));
  ASSERT_EQ(EINVAL, errno);

  // Good signal numbers, low and high ends of range.
  errno = 0;
  ASSERT_EQ(0, fn(&set, SIGNAL_MIN()));
  ASSERT_EQ(0, errno);
  ASSERT_EQ(0, fn(&set, SIGNAL_MAX()));
  ASSERT_EQ(0, errno);
}

TEST(signal, sigismember_invalid) {
  TestSigSet2(sigismember);
}

TEST(signal, sigaddset_invalid) {
  TestSigSet2(sigaddset);
}

TEST(signal, sigdelset_invalid) {
  TestSigSet2(sigdelset);
}

TEST(signal, sigemptyset_invalid) {
  TestSigSet1(sigemptyset);
}

TEST(signal, sigfillset_invalid) {
  TestSigSet1(sigfillset);
}

TEST(signal, raise_invalid) {
  errno = 0;
  ASSERT_EQ(-1, raise(-1));
  ASSERT_EQ(EINVAL, errno);
}

static void raise_in_signal_handler_helper(int signal_number) {
  ASSERT_EQ(SIGALRM, signal_number);
  static int count = 0;
  if (++count == 1) {
    raise(SIGALRM);
  }
}

TEST(signal, raise_in_signal_handler) {
  ScopedSignalHandler ssh(SIGALRM, raise_in_signal_handler_helper);
  raise(SIGALRM);
}

static void HandleSIGALRM(int signal_number) {
  ASSERT_EQ(SIGALRM, signal_number);
}

TEST(signal, sigwait) {
  ScopedSignalHandler ssh(SIGALRM, HandleSIGALRM);

  sigset_t wait_set;
  sigemptyset(&wait_set);
  sigaddset(&wait_set, SIGALRM);

  alarm(1);

  int received_signal;
  errno = 0;
  ASSERT_EQ(0, sigwait(&wait_set, &received_signal));
  ASSERT_EQ(0, errno);
  ASSERT_EQ(SIGALRM, received_signal);
}

static int g_sigsuspend_test_helper_call_count = 0;

static void SigSuspendTestHelper(int) {
  ++g_sigsuspend_test_helper_call_count;
}

TEST(signal, sigsuspend_sigpending) {
  // Block SIGALRM.
  sigset_t just_SIGALRM;
  sigemptyset(&just_SIGALRM);
  sigaddset(&just_SIGALRM, SIGALRM);
  sigset_t original_set;
  ASSERT_EQ(0, sigprocmask(SIG_BLOCK, &just_SIGALRM, &original_set));

  ScopedSignalHandler ssh(SIGALRM, SigSuspendTestHelper);

  // There should be no pending signals.
  sigset_t pending;
  sigemptyset(&pending);
  ASSERT_EQ(0, sigpending(&pending));
  for (size_t i = SIGNAL_MIN(); i <= SIGNAL_MAX(); ++i) {
    EXPECT_FALSE(sigismember(&pending, i)) << i;
  }

  // Raise SIGALRM and check our signal handler wasn't called.
  raise(SIGALRM);
  ASSERT_EQ(0, g_sigsuspend_test_helper_call_count);

  // We should now have a pending SIGALRM but nothing else.
  sigemptyset(&pending);
  ASSERT_EQ(0, sigpending(&pending));
  for (size_t i = SIGNAL_MIN(); i <= SIGNAL_MAX(); ++i) {
    EXPECT_EQ((i == SIGALRM), sigismember(&pending, i));
  }

  // Use sigsuspend to block everything except SIGALRM...
  sigset_t not_SIGALRM;
  sigfillset(&not_SIGALRM);
  sigdelset(&not_SIGALRM, SIGALRM);
  ASSERT_EQ(-1, sigsuspend(&not_SIGALRM));
  ASSERT_EQ(EINTR, errno);
  // ...and check that we now receive our pending SIGALRM.
  ASSERT_EQ(1, g_sigsuspend_test_helper_call_count);

  // Restore the original set.
  ASSERT_EQ(0, sigprocmask(SIG_SETMASK, &original_set, NULL));
}

static void EmptySignalHandler(int) {}
static void EmptySignalAction(int, siginfo_t*, void*) {}

TEST(signal, sigaction) {
  // Both bionic and glibc set SA_RESTORER when talking to the kernel on arm,
  // arm64, x86, and x86-64. The version of glibc we're using also doesn't
  // define SA_RESTORER, but luckily it's the same value everywhere, and mips
  // doesn't use the bit for anything.
  static const unsigned sa_restorer = 0x4000000;

  // See what's currently set for SIGALRM.
  struct sigaction original_sa;
  memset(&original_sa, 0, sizeof(original_sa));
  ASSERT_EQ(0, sigaction(SIGALRM, NULL, &original_sa));
  ASSERT_TRUE(original_sa.sa_handler == NULL);
  ASSERT_TRUE(original_sa.sa_sigaction == NULL);
  ASSERT_EQ(0U, original_sa.sa_flags & ~sa_restorer);

  // Set a traditional sa_handler signal handler.
  struct sigaction sa;
  memset(&sa, 0, sizeof(sa));
  sigaddset(&sa.sa_mask, SIGALRM);
  sa.sa_flags = SA_ONSTACK;
  sa.sa_handler = EmptySignalHandler;
  ASSERT_EQ(0, sigaction(SIGALRM, &sa, NULL));

  // Check that we can read it back.
  memset(&sa, 0, sizeof(sa));
  ASSERT_EQ(0, sigaction(SIGALRM, NULL, &sa));
  ASSERT_TRUE(sa.sa_handler == EmptySignalHandler);
  ASSERT_TRUE((void*) sa.sa_sigaction == (void*) sa.sa_handler);
  ASSERT_EQ(static_cast<unsigned>(SA_ONSTACK), sa.sa_flags & ~sa_restorer);

  // Set a new-style sa_sigaction signal handler.
  memset(&sa, 0, sizeof(sa));
  sigaddset(&sa.sa_mask, SIGALRM);
  sa.sa_flags = SA_ONSTACK | SA_SIGINFO;
  sa.sa_sigaction = EmptySignalAction;
  ASSERT_EQ(0, sigaction(SIGALRM, &sa, NULL));

  // Check that we can read it back.
  memset(&sa, 0, sizeof(sa));
  ASSERT_EQ(0, sigaction(SIGALRM, NULL, &sa));
  ASSERT_TRUE(sa.sa_sigaction == EmptySignalAction);
  ASSERT_TRUE((void*) sa.sa_sigaction == (void*) sa.sa_handler);
  ASSERT_EQ(static_cast<unsigned>(SA_ONSTACK | SA_SIGINFO), sa.sa_flags & ~sa_restorer);

  // Put everything back how it was.
  ASSERT_EQ(0, sigaction(SIGALRM, &original_sa, NULL));
}

TEST(signal, sys_signame) {
#if defined(__BIONIC__)
  ASSERT_TRUE(sys_signame[0] == NULL);
  ASSERT_STREQ("HUP", sys_signame[SIGHUP]);
#else
  GTEST_LOG_(INFO) << "This test does nothing.\n";
#endif
}

TEST(signal, sys_siglist) {
  ASSERT_TRUE(sys_siglist[0] == NULL);
  ASSERT_STREQ("Hangup", sys_siglist[SIGHUP]);
}

TEST(signal, limits) {
  // This comes from the kernel.
  ASSERT_EQ(32, __SIGRTMIN);

  // We reserve a non-zero number at the bottom for ourselves.
  ASSERT_GT(SIGRTMIN, __SIGRTMIN);

  // MIPS has more signals than everyone else.
#if defined(__mips__)
  ASSERT_EQ(128, __SIGRTMAX);
#else
  ASSERT_EQ(64, __SIGRTMAX);
#endif

  // We don't currently reserve any at the top.
  ASSERT_EQ(SIGRTMAX, __SIGRTMAX);
}