sigchain: add test.

Add a gtest for the various sigchain wrappers.

Bug: http://b/73344857
Test: adb shell /data/nativetest64/art/arm64/art_sigchain_tests/sigchain_test
      (with several actual failures)
Change-Id: I331da4f44008984723e2e2733e2a6dd66658e704
diff --git a/sigchainlib/sigchain_test.cc b/sigchainlib/sigchain_test.cc
new file mode 100644
index 0000000..9f338ad
--- /dev/null
+++ b/sigchainlib/sigchain_test.cc
@@ -0,0 +1,187 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *  * Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ *  * Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
+ * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+
+#include <signal.h>
+#include <sys/syscall.h>
+
+#include <functional>
+
+#include <gtest/gtest.h>
+
+#include "sigchain.h"
+
+#if !defined(__BIONIC__)
+typedef sigset_t sigset64_t;
+
+static int sigemptyset64(sigset64_t* set) {
+  return sigemptyset(set);
+}
+
+static int sigismember64(sigset64_t* set, int member) {
+  return sigismember(set, member);
+}
+#endif
+
+static int RealSigprocmask(int how, const sigset64_t* new_sigset, sigset64_t* old_sigset) {
+  // glibc's sigset_t is overly large, so sizeof(*new_sigset) doesn't work.
+  return syscall(__NR_rt_sigprocmask, how, new_sigset, old_sigset, 8);
+}
+
+class SigchainTest : public ::testing::Test {
+  void SetUp() final {
+    art::AddSpecialSignalHandlerFn(SIGSEGV, &action);
+  }
+
+  void TearDown() final {
+    art::RemoveSpecialSignalHandlerFn(SIGSEGV, action.sc_sigaction);
+  }
+
+  art::SigchainAction action = {
+      .sc_sigaction = [](int, siginfo_t*, void*) { return true; },
+      .sc_mask = {},
+      .sc_flags = 0,
+  };
+};
+
+
+static void TestSignalBlocking(std::function<void()> fn) {
+  // Unblock SIGSEGV, make sure it stays unblocked.
+  sigset64_t mask;
+  sigemptyset64(&mask);
+  ASSERT_EQ(0, RealSigprocmask(SIG_SETMASK, &mask, nullptr)) << strerror(errno);
+
+  fn();
+
+  if (testing::Test::HasFatalFailure()) return;
+  ASSERT_EQ(0, RealSigprocmask(SIG_SETMASK, nullptr, &mask));
+  ASSERT_FALSE(sigismember64(&mask, SIGSEGV));
+}
+
+TEST_F(SigchainTest, sigprocmask_setmask) {
+  TestSignalBlocking([]() {
+    sigset_t mask;
+    sigfillset(&mask);
+    ASSERT_EQ(0, sigprocmask(SIG_SETMASK, &mask, nullptr));
+  });
+}
+
+TEST_F(SigchainTest, sigprocmask_block) {
+  TestSignalBlocking([]() {
+    sigset_t mask;
+    sigfillset(&mask);
+    ASSERT_EQ(0, sigprocmask(SIG_BLOCK, &mask, nullptr));
+  });
+}
+
+// bionic-only wide variants for LP32.
+#if defined(__BIONIC__)
+TEST_F(SigchainTest, sigprocmask64_setmask) {
+  TestSignalBlocking([]() {
+    sigset64_t mask;
+    sigfillset64(&mask);
+    ASSERT_EQ(0, sigprocmask64(SIG_SETMASK, &mask, nullptr));
+  });
+}
+
+TEST_F(SigchainTest, sigprocmask64_block) {
+  TestSignalBlocking([]() {
+    sigset64_t mask;
+    sigfillset64(&mask);
+    ASSERT_EQ(0, sigprocmask64(SIG_BLOCK, &mask, nullptr));
+  });
+}
+
+TEST_F(SigchainTest, pthread_sigmask64_setmask) {
+  TestSignalBlocking([]() {
+    sigset64_t mask;
+    sigfillset64(&mask);
+    ASSERT_EQ(0, pthread_sigmask64(SIG_SETMASK, &mask, nullptr));
+  });
+}
+
+TEST_F(SigchainTest, pthread_sigmask64_block) {
+  TestSignalBlocking([]() {
+    sigset64_t mask;
+    sigfillset64(&mask);
+    ASSERT_EQ(0, pthread_sigmask64(SIG_BLOCK, &mask, nullptr));
+  });
+}
+#endif
+
+// glibc doesn't implement most of these in terms of sigprocmask, which we rely on.
+#if defined(__BIONIC__)
+TEST_F(SigchainTest, pthread_sigmask_setmask) {
+  TestSignalBlocking([]() {
+    sigset_t mask;
+    sigfillset(&mask);
+    ASSERT_EQ(0, pthread_sigmask(SIG_SETMASK, &mask, nullptr));
+  });
+}
+
+TEST_F(SigchainTest, pthread_sigmask_block) {
+  TestSignalBlocking([]() {
+    sigset_t mask;
+    sigfillset(&mask);
+    ASSERT_EQ(0, pthread_sigmask(SIG_BLOCK, &mask, nullptr));
+  });
+}
+
+TEST_F(SigchainTest, sigset_mask) {
+  TestSignalBlocking([]() {
+    sigset(SIGSEGV, SIG_HOLD);
+  });
+}
+
+TEST_F(SigchainTest, sighold) {
+  TestSignalBlocking([]() {
+    sighold(SIGSEGV);
+  });
+}
+
+#if defined(__BIONIC__)
+// Not exposed via headers, but the symbols are available if you declare them yourself.
+extern "C" int sigblock(int);
+extern "C" int sigsetmask(int);
+#endif
+
+TEST_F(SigchainTest, sigblock) {
+  TestSignalBlocking([]() {
+    int mask = ~0U;
+    ASSERT_EQ(0, sigblock(mask));
+  });
+}
+
+TEST_F(SigchainTest, sigsetmask) {
+  TestSignalBlocking([]() {
+    int mask = ~0U;
+    ASSERT_EQ(0, sigsetmask(mask));
+  });
+}
+
+#endif