Revert of Non-SFI mode: Add Linux asynchronous signal support

tests/nonsfi/user_async_signal_test.cc

-/*
- * Copyright (c) 2015 The Native Client Authors. All rights reserved.
- * Use of this source code is governed by a BSD-style license that can be
- * found in the LICENSE file.
- */
-
-#include <pthread.h>
-#include <semaphore.h>
-
-#include "native_client/src/include/nacl_assert.h"
-#include "native_client/src/untrusted/irt/irt.h"
-#include "native_client/src/untrusted/nacl/nacl_irt.h"
-#include "native_client/src/untrusted/nacl/nacl_thread.h"
-
-#define CHECK_OK(expr) ASSERT_EQ(expr, 0)
-
-namespace {
-
-struct nacl_irt_thread_v0_2 libnacl_irt_thread_v0_2;
-struct nacl_irt_async_signal_handling libnacl_irt_async_signal_handling;
-
-volatile int g_signal_count;
-volatile int g_signal_arrived;
-volatile int g_test_running;
-nacl_irt_tid_t g_child_tid;
-void *g_expected_tls;
-sem_t g_sem;
-
-int thread_create_wrapper(void (*start_func)(void), void *stack,
-                          void *thread_ptr) {
-  return libnacl_irt_thread_v0_2.thread_create(start_func, stack, thread_ptr,
-                                               &g_child_tid);
-}
-
-int set_async_signal_handler(NaClIrtAsyncSignalHandler handler) {
-  return libnacl_irt_async_signal_handling.set_async_signal_handler(handler);
-}
-
-int send_async_signal(nacl_irt_tid_t tid) {
-  return libnacl_irt_async_signal_handling.send_async_signal(tid);
-}
-
-/*
- * Check that sending a signal before initializing signal support will result in
- * an error.
- */
-void test_send_signal_before_set_handler() {
-  int retval = send_async_signal(0);
-  ASSERT_EQ(retval, ESRCH);
-}
-
-/*
- * Check that nacl_tls_get() is async-signal-safe.
- */
-void tls_get_signal_handler(NaClExceptionContext *exc) {
-  if (!g_test_running)
-    return;
-  ASSERT_EQ(nacl_tls_get(), g_expected_tls);
-  g_signal_count++;
-  g_signal_arrived = 1;
-}
-
-void *tls_get_thread_func(void *arg) {
-  g_expected_tls = nacl_tls_get();
-  CHECK_OK(sem_post(&g_sem));
-  while (g_test_running) {
-    ASSERT_EQ(nacl_tls_get(), g_expected_tls);
-    if (__sync_bool_compare_and_swap(&g_signal_arrived, 1, 0)) {
-      CHECK_OK(sem_post(&g_sem));
-    }
-  }
-  return NULL;
-}
-
-void test_async_safe_tls_get() {
-  CHECK_OK(sem_init(&g_sem, 0, 0));
-  CHECK_OK(set_async_signal_handler(tls_get_signal_handler));
-
-  pthread_t tid;
-  g_signal_count = 0;
-  g_signal_arrived = 0;
-  g_test_running = true;
-  CHECK_OK(pthread_create(&tid, NULL, tls_get_thread_func, NULL));
-
-  CHECK_OK(sem_wait(&g_sem));
-  const int kSignalCount = 1000;
-  for (int i = 0; i < kSignalCount; i++) {
-    CHECK_OK(send_async_signal(g_child_tid));
-    CHECK_OK(sem_wait(&g_sem));
-  }
-  g_test_running = false;
-  /* Send a last signal to make sure any waiting syscalls get interrupted. */
-  CHECK_OK(send_async_signal(g_child_tid));
-  CHECK_OK(pthread_join(tid, NULL));
-  ASSERT_EQ(g_signal_count, kSignalCount);
-  CHECK_OK(sem_destroy(&g_sem));
-}
-
-#if !defined(__arm__)
-/* This test is broken on QEMU. */
-
-/*
- * Check that both futex_wake() and futex_wait_abs() are signal-async-safe.
- */
-void futex_signal_handler(NaClExceptionContext *exc) {
-  int count = 0;
-  ASSERT_EQ(__sync_bool_compare_and_swap(&g_signal_arrived, 0, 1), 1);
-  CHECK_OK(__libnacl_irt_futex.futex_wake(&g_signal_arrived, INT_MAX, &count));
-  /*
-   * |count| is always 0 since the thread waiting is now running the signal
-   * handler, so it did not actually count as a wakeup.
-   */
-  ASSERT_EQ(count, 0);
-  if (g_test_running)
-    g_signal_count++;
-}
-
-void *futex_thread_func(void *arg) {
-  CHECK_OK(sem_post(&g_sem));
-  struct timespec timeout;
-  /*
-   * Make the timeout be the current time plus 10 seconds. This timeout should
-   * never kick in, but if it does it means we deadlocked, so it's better to
-   * assert than letting the job itself time out.
-   */
-  clock_gettime(CLOCK_REALTIME, &timeout);
-  timeout.tv_sec += 10;
-  while (g_test_running) {
-    int retval = __libnacl_irt_futex.futex_wait_abs(&g_signal_arrived, 0,
-                                                    &timeout);
-    if (retval == EWOULDBLOCK) {
-      /*
-       * The signal handler executed before we could wait and changed the value
-       * of |g_signal_arrived|.
-       */
-    } else {
-      /*
-       * futex_wait_abs, when provided with a non-NULL timeout argument, can be
-       * interrupted and will set errno to EINTR. This can happen even if the
-       * SA_RESTART flag was used.
-       */
-      ASSERT_EQ(retval, EINTR);
-    }
-    ASSERT_EQ(__sync_bool_compare_and_swap(&g_signal_arrived, 1, 0), 1);
-    /*
-     * Have to test again since we could have gone sleeping again after the last
-     * iteration.
-     */
-    if (g_test_running)
-      CHECK_OK(sem_post(&g_sem));
-  }
-  return NULL;
-}
-
-void test_async_safe_futex() {
-  CHECK_OK(sem_init(&g_sem, 0, 0));
-  CHECK_OK(set_async_signal_handler(futex_signal_handler));
-
-  pthread_t tid;
-  g_signal_count = 0;
-  g_signal_arrived = 0;
-  g_test_running = true;
-  CHECK_OK(pthread_create(&tid, NULL, futex_thread_func, NULL));
-
-  CHECK_OK(sem_wait(&g_sem));
-  const int kSignalCount = 1000;
-  for (int i = 0; i < kSignalCount; i++) {
-    CHECK_OK(send_async_signal(g_child_tid));
-    CHECK_OK(sem_wait(&g_sem));
-  }
-  g_test_running = false;
-  /* Send a last signal to make sure any waiting syscalls get interrupted. */
-  CHECK_OK(send_async_signal(g_child_tid));
-  CHECK_OK(pthread_join(tid, NULL));
-  ASSERT_EQ(g_signal_count, kSignalCount);
-  CHECK_OK(sem_destroy(&g_sem));
-}
-
-#endif
-
-/*
- * Check that futex_wait_abs() with no timeout is restarted.
- * As opposed to the above test with futex, the signal handler does not try to
- * wake the thread up, since it will sometimes be called _after_ the
- * futex_wait_abs() returns.
- */
-void futex_wait_signal_handler(NaClExceptionContext *exc) {
-  ASSERT_EQ(__sync_bool_compare_and_swap(&g_signal_arrived, 0, 1), 1);
-}
-
-void *futex_wait_thread_func(void *arg) {
-  volatile int *futex = (volatile int *)arg;
-  CHECK_OK(sem_post(&g_sem));
-  while (g_test_running) {
-    /*
-     * Unfortunately, Linux sometimes can return 0 (instead of EINTR) on
-     * futex_wait_abs() when it is spuriously woken up.
-     */
-    while (*futex == 0) {
-      int retval = __libnacl_irt_futex.futex_wait_abs(futex, 0, NULL);
-      if (retval != EWOULDBLOCK)
-        ASSERT_EQ(retval, 0);
-    }
-    ASSERT_EQ(__sync_bool_compare_and_swap(futex, 1, 0), 1);
-
-    /*
-     * Have to test again since we could have gone sleeping again after the last
-     * iteration.
-     */
-    if (g_test_running) {
-      ASSERT_EQ(__sync_bool_compare_and_swap(&g_signal_arrived, 1, 0), 1);
-      g_signal_count++;
-      CHECK_OK(sem_post(&g_sem));
-    }
-  }
-  return NULL;
-}
-
-void test_futex_wait_restart() {
-  CHECK_OK(sem_init(&g_sem, 0, 0));
-  CHECK_OK(set_async_signal_handler(futex_wait_signal_handler));
-
-  pthread_t tid;
-  g_signal_count = 0;
-  g_signal_arrived = 0;
-  volatile int futex = 0;
-  g_test_running = true;
-  CHECK_OK(pthread_create(&tid, NULL, futex_wait_thread_func, (void *)&futex));
-
-  CHECK_OK(sem_wait(&g_sem));
-  const int kSignalCount = 1000;
-  int count = 0;
-  for (int i = 0; i < kSignalCount; i++) {
-    /* Yield to the other process to try and get it in the desired state. */
-    sched_yield();
-    CHECK_OK(send_async_signal(g_child_tid));
-    sched_yield();
-
-    /* Wake it up using futex. This time, |count| may be 1. */
-    ASSERT_EQ(__sync_bool_compare_and_swap(&futex, 0, 1), 1);
-    CHECK_OK(__libnacl_irt_futex.futex_wake(&futex, INT_MAX, &count));
-    ASSERT_LE(count, 1);
-
-    CHECK_OK(sem_wait(&g_sem));
-  }
-  g_test_running = false;
-  /*
-   * Wake the thread up again in case it waited again.
-   */
-  __sync_bool_compare_and_swap(&futex, 0, 1);
-  CHECK_OK(__libnacl_irt_futex.futex_wake(&futex, INT_MAX, &count));
-  CHECK_OK(pthread_join(tid, NULL));
-  ASSERT_EQ(g_signal_count, kSignalCount);
-  CHECK_OK(sem_destroy(&g_sem));
-}
-
-/*
- * Check that send_async_signal() is async-signal-safe.
- */
-void signal_signal_handler(NaClExceptionContext *exc) {
-  if (!g_test_running)
-    return;
-  if (++g_signal_count % 2 == 1) {
-    CHECK_OK(send_async_signal(g_child_tid));
-    g_signal_arrived = 1;
-  }
-}
-
-void *signal_thread_func(void *arg) {
-  CHECK_OK(sem_post(&g_sem));
-  struct timespec req, rem;
-  /*
-   * In case we are unlucky and the signal arrives before the first sleep, limit
-   * the time sleeping to 10 msec.
-   */
-  req.tv_sec = 0;
-  req.tv_nsec = 10000000;
-  while (g_test_running) {
-    while (g_test_running && !g_signal_arrived) {
-      int retval = nanosleep(&req, &rem);
-      if (retval != 0)
-        ASSERT_EQ(errno, EINTR);
-    }
-    /*
-     * Have to test again since we could have gone sleeping again after the last
-     * iteration.
-     */
-    if (!g_test_running)
-      break;
-    g_signal_arrived = 0;
-    CHECK_OK(sem_post(&g_sem));
-  }
-  return NULL;
-}
-
-void test_async_safe_signal() {
-  CHECK_OK(sem_init(&g_sem, 0, 0));
-  CHECK_OK(set_async_signal_handler(signal_signal_handler));
-
-  pthread_t tid;
-  g_test_running = true;
-  g_signal_count = 0;
-  g_signal_arrived = 0;
-  CHECK_OK(pthread_create(&tid, NULL, signal_thread_func, NULL));
-
-  CHECK_OK(sem_wait(&g_sem));
-  const int kSignalCount = 1000;
-  for (int i = 0; i < kSignalCount; i++) {
-    CHECK_OK(send_async_signal(g_child_tid));
-    CHECK_OK(sem_wait(&g_sem));
-  }
-  g_test_running = false;
-  /* Send a last signal to make sure any waiting syscalls get interrupted. */
-  CHECK_OK(send_async_signal(g_child_tid));
-  CHECK_OK(pthread_join(tid, NULL));
-  ASSERT_EQ(g_signal_count, 2 * kSignalCount);
-  CHECK_OK(sem_destroy(&g_sem));
-}
-
-/*
- * Check that passing 0 as |tid| to send_async_signal() works and
- * sends a signal to the main thread.
- */
-void main_signal_handler(NaClExceptionContext *exc) {
-  g_signal_count = 1;
-}
-
-void test_main_signal() {
-  CHECK_OK(set_async_signal_handler(main_signal_handler));
-
-  g_signal_count = 0;
-  CHECK_OK(send_async_signal(NACL_IRT_MAIN_THREAD_TID));
-  ASSERT_EQ(g_signal_count, 1);
-}
-
-void run_test(const char *test_name, void (*test_func)(void)) {
-  printf("Running %s...\n", test_name);
-  test_func();
-}
-
-}  // namespace
-
-#define RUN_TEST(test_func) (run_test(#test_func, test_func))
-
-int main(void) {
-  size_t bytes;
-  bytes = nacl_interface_query(NACL_IRT_THREAD_v0_2, &libnacl_irt_thread_v0_2,
-                               sizeof(libnacl_irt_thread_v0_2));
-  ASSERT_EQ(bytes, sizeof(libnacl_irt_thread_v0_2));
-
-  bytes = nacl_interface_query(NACL_IRT_ASYNC_SIGNAL_HANDLING_v0_1,
-                               &libnacl_irt_async_signal_handling,
-                               sizeof(libnacl_irt_async_signal_handling));
-  ASSERT_EQ(bytes, sizeof(libnacl_irt_async_signal_handling));
-
-  /*
-   * In order to avoid modifying the libpthread implementation to save the
-   * native tid, wrap that functionality so the tid is stored in a global
-   * variable.
-   */
-  __libnacl_irt_thread.thread_create = &thread_create_wrapper;
-
-  RUN_TEST(test_send_signal_before_set_handler);
-
-  RUN_TEST(test_async_safe_tls_get);
-#if !defined(__arm__)
-  /*
-   * Signals are sometimes delivered after the futex_wait syscall returns (as
-   * opposed to interrupting it), which breaks this test.
-   *
-   * This problem only seems to happen in QEMU.
-   */
-  RUN_TEST(test_async_safe_futex);
-#endif
-  RUN_TEST(test_futex_wait_restart);
-  RUN_TEST(test_async_safe_signal);
-  RUN_TEST(test_main_signal);
-
-  printf("Done\n");
-
-  return 0;
-}