LibNativeBridge: Version 2

Add a callback function to retrieve "signal handler" from the bridge,
if the bridge wants it to be managed by the runtime. The signal handler
will be invoked after the runtime's own one, and before any other
chained handler.

Add a callback function to check compatibility of the bridge with the
library.

Add a function to expose the native bridge version. Add a test for this
function.

Bug: 20217701

(cherry picked from commit a6ac9ce98bd38099a4e89010111d14e4d5fc190e)

Change-Id: Ic23a60b949f119c7d8b0e7cb27a61e6c16532a23

6 files changed, 230 insertions, 6 deletions

diff --git a/libnativebridge/native_bridge.cc b/libnativebridge/native_bridge.cc
index 6fa4b39..f63497b 100644
--- a/libnativebridge/native_bridge.cc
+++ b/libnativebridge/native_bridge.cc
@@ -83,7 +83,7 @@ static bool had_error = false;
 static void* native_bridge_handle = nullptr;
 // Pointer to the callbacks. Available as soon as LoadNativeBridge succeeds, but only initialized
 // later.
-static NativeBridgeCallbacks* callbacks = nullptr;
+static const NativeBridgeCallbacks* callbacks = nullptr;
 // Callbacks provided by the environment to the bridge. Passed to LoadNativeBridge.
 static const NativeBridgeRuntimeCallbacks* runtime_callbacks = nullptr;
 
@@ -96,7 +96,7 @@ static char* app_code_cache_dir = nullptr;
 // and hard code the directory name again here.
 static constexpr const char* kCodeCacheDir = "code_cache";
 
-static constexpr uint32_t kNativeBridgeCallbackVersion = 1;
+static constexpr uint32_t kLibNativeBridgeVersion = 2;
 
 // Characters allowed in a native bridge filename. The first character must
 // be in [a-zA-Z] (expected 'l' for "libx"). The rest must be in [a-zA-Z0-9._-].
@@ -121,7 +121,9 @@ bool NativeBridgeNameAcceptable(const char* nb_library_filename) {
     // First character must be [a-zA-Z].
     if (!CharacterAllowed(*ptr, true))  {
       // Found an invalid fist character, don't accept.
-      ALOGE("Native bridge library %s has been rejected for first character %c", nb_library_filename, *ptr);
+      ALOGE("Native bridge library %s has been rejected for first character %c",
+            nb_library_filename,
+            *ptr);
       return false;
     } else {
       // For the rest, be more liberal.
@@ -139,8 +141,22 @@ bool NativeBridgeNameAcceptable(const char* nb_library_filename) {
   }
 }
 
-static bool VersionCheck(NativeBridgeCallbacks* cb) {
-  return cb != nullptr && cb->version == kNativeBridgeCallbackVersion;
+static bool VersionCheck(const NativeBridgeCallbacks* cb) {
+  // Libnativebridge is now designed to be forward-compatible. So only "0" is an unsupported
+  // version.
+  if (cb == nullptr || cb->version == 0) {
+    return false;
+  }
+
+  // If this is a v2+ bridge, it may not be forwards- or backwards-compatible. Check.
+  if (cb->version >= 2) {
+    if (!callbacks->isCompatibleWith(kLibNativeBridgeVersion)) {
+      // TODO: Scan which version is supported, and fall back to handle it.
+      return false;
+    }
+  }
+
+  return true;
 }
 
 static void CloseNativeBridge(bool with_error) {
@@ -321,7 +337,7 @@ static void SetCpuAbi(JNIEnv* env, jclass build_class, const char* field, const
 }
 
 // Set up the environment for the bridged app.
-static void SetupEnvironment(NativeBridgeCallbacks* callbacks, JNIEnv* env, const char* isa) {
+static void SetupEnvironment(const NativeBridgeCallbacks* callbacks, JNIEnv* env, const char* isa) {
   // Need a JNIEnv* to do anything.
   if (env == nullptr) {
     ALOGW("No JNIEnv* to set up app environment.");
@@ -485,4 +501,18 @@ bool NativeBridgeIsSupported(const char* libpath) {
   return false;
 }
 
+uint32_t NativeBridgeGetVersion() {
+  if (NativeBridgeAvailable()) {
+    return callbacks->version;
+  }
+  return 0;
+}
+
+NativeBridgeSignalHandlerFn NativeBridgeGetSignalHandler(int signal) {
+  if (NativeBridgeInitialized() && callbacks->version >= 2) {
+    return callbacks->getSignalHandler(signal);
+  }
+  return nullptr;
+}
+
 };  // namespace android
diff --git a/libnativebridge/tests/Android.mk b/libnativebridge/tests/Android.mk
index f28c490..285e8c2 100644
--- a/libnativebridge/tests/Android.mk
+++ b/libnativebridge/tests/Android.mk
@@ -11,6 +11,8 @@ test_src_files := \
     CodeCacheExists_test.cpp \
     CompleteFlow_test.cpp \
     InvalidCharsNativeBridge_test.cpp \
+    NativeBridge2Signal_test.cpp \
+    NativeBridgeVersion_test.cpp \
     NeedsNativeBridge_test.cpp \
     PreInitializeNativeBridge_test.cpp \
     PreInitializeNativeBridgeFail1_test.cpp \
diff --git a/libnativebridge/tests/Android.nativebridge-dummy.mk b/libnativebridge/tests/Android.nativebridge-dummy.mk
index 1caf50a..2efc176 100644
--- a/libnativebridge/tests/Android.nativebridge-dummy.mk
+++ b/libnativebridge/tests/Android.nativebridge-dummy.mk
@@ -32,3 +32,39 @@ LOCAL_LDFLAGS := -ldl
 LOCAL_MULTILIB := both
 
 include $(BUILD_HOST_SHARED_LIBRARY)
+
+
+# v2.
+
+NATIVE_BRIDGE2_COMMON_SRC_FILES := \
+  DummyNativeBridge2.cpp
+
+# Shared library for target
+# ========================================================
+include $(CLEAR_VARS)
+
+LOCAL_MODULE:= libnativebridge2-dummy
+
+LOCAL_SRC_FILES:= $(NATIVE_BRIDGE2_COMMON_SRC_FILES)
+LOCAL_CLANG := true
+LOCAL_CFLAGS += -Werror -Wall
+LOCAL_CPPFLAGS := -std=gnu++11 -fvisibility=protected
+LOCAL_LDFLAGS := -ldl
+LOCAL_MULTILIB := both
+
+include $(BUILD_SHARED_LIBRARY)
+
+# Shared library for host
+# ========================================================
+include $(CLEAR_VARS)
+
+LOCAL_MODULE:= libnativebridge2-dummy
+
+LOCAL_SRC_FILES:= $(NATIVE_BRIDGE2_COMMON_SRC_FILES)
+LOCAL_CLANG := true
+LOCAL_CFLAGS += -Werror -Wall
+LOCAL_CPPFLAGS := -std=gnu++11 -fvisibility=protected
+LOCAL_LDFLAGS := -ldl
+LOCAL_MULTILIB := both
+
+include $(BUILD_HOST_SHARED_LIBRARY)
diff --git a/libnativebridge/tests/DummyNativeBridge2.cpp b/libnativebridge/tests/DummyNativeBridge2.cpp
new file mode 100644
index 0000000..6920c74
--- /dev/null
+++ b/libnativebridge/tests/DummyNativeBridge2.cpp
@@ -0,0 +1,76 @@
+/*
+ * Copyright (C) 2014 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.
+ */
+
+// A dummy implementation of the native-bridge interface.
+
+#include "nativebridge/native_bridge.h"
+
+#include <signal.h>
+
+// NativeBridgeCallbacks implementations
+extern "C" bool native_bridge2_initialize(const android::NativeBridgeRuntimeCallbacks* /* art_cbs */,
+                                         const char* /* app_code_cache_dir */,
+                                         const char* /* isa */) {
+  return true;
+}
+
+extern "C" void* native_bridge2_loadLibrary(const char* /* libpath */, int /* flag */) {
+  return nullptr;
+}
+
+extern "C" void* native_bridge2_getTrampoline(void* /* handle */, const char* /* name */,
+                                             const char* /* shorty */, uint32_t /* len */) {
+  return nullptr;
+}
+
+extern "C" bool native_bridge2_isSupported(const char* /* libpath */) {
+  return false;
+}
+
+extern "C" const struct android::NativeBridgeRuntimeValues* native_bridge2_getAppEnv(
+    const char* /* abi */) {
+  return nullptr;
+}
+
+extern "C" bool native_bridge2_is_compatible_compatible_with(uint32_t version) {
+  // For testing, allow 1 and 2, but disallow 3+.
+  return version <= 2;
+}
+
+static bool native_bridge2_dummy_signal_handler(int, siginfo_t*, void*) {
+  // TODO: Implement something here. We'd either have to have a death test with a log here, or
+  //       we'd have to be able to resume after the faulting instruction...
+  return true;
+}
+
+extern "C" android::NativeBridgeSignalHandlerFn native_bridge2_get_signal_handler(int signal) {
+  if (signal == SIGSEGV) {
+    return &native_bridge2_dummy_signal_handler;
+  }
+  return nullptr;
+}
+
+android::NativeBridgeCallbacks NativeBridgeItf {
+  .version = 2,
+  .initialize = &native_bridge2_initialize,
+  .loadLibrary = &native_bridge2_loadLibrary,
+  .getTrampoline = &native_bridge2_getTrampoline,
+  .isSupported = &native_bridge2_isSupported,
+  .getAppEnv = &native_bridge2_getAppEnv,
+  .isCompatibleWith = &native_bridge2_is_compatible_compatible_with,
+  .getSignalHandler = &native_bridge2_get_signal_handler
+};
+
diff --git a/libnativebridge/tests/NativeBridge2Signal_test.cpp b/libnativebridge/tests/NativeBridge2Signal_test.cpp
new file mode 100644
index 0000000..44e45e3
--- /dev/null
+++ b/libnativebridge/tests/NativeBridge2Signal_test.cpp
@@ -0,0 +1,42 @@
+/*
+ * Copyright (C) 2014 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 "NativeBridgeTest.h"
+
+#include <signal.h>
+#include <unistd.h>
+
+namespace android {
+
+constexpr const char* kNativeBridgeLibrary2 = "libnativebridge2-dummy.so";
+
+TEST_F(NativeBridgeTest, V2_Signal) {
+    // Init
+    ASSERT_TRUE(LoadNativeBridge(kNativeBridgeLibrary2, nullptr));
+    ASSERT_TRUE(NativeBridgeAvailable());
+    ASSERT_TRUE(PreInitializeNativeBridge(".", "isa"));
+    ASSERT_TRUE(NativeBridgeAvailable());
+    ASSERT_TRUE(InitializeNativeBridge(nullptr, nullptr));
+    ASSERT_TRUE(NativeBridgeAvailable());
+
+    ASSERT_EQ(2U, NativeBridgeGetVersion());
+    ASSERT_NE(nullptr, NativeBridgeGetSignalHandler(SIGSEGV));
+
+    // Clean-up code_cache
+    ASSERT_EQ(0, rmdir(kCodeCache));
+}
+
+}  // namespace android
diff --git a/libnativebridge/tests/NativeBridgeVersion_test.cpp b/libnativebridge/tests/NativeBridgeVersion_test.cpp
new file mode 100644
index 0000000..d3f9a80
--- /dev/null
+++ b/libnativebridge/tests/NativeBridgeVersion_test.cpp
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2015 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 "NativeBridgeTest.h"
+
+#include <unistd.h>
+
+namespace android {
+
+TEST_F(NativeBridgeTest, Version) {
+    // When a bridge isn't loaded, we expect 0.
+    EXPECT_EQ(NativeBridgeGetVersion(), 0U);
+
+    // After our dummy bridge has been loaded, we expect 1.
+    ASSERT_TRUE(LoadNativeBridge(kNativeBridgeLibrary, nullptr));
+    EXPECT_EQ(NativeBridgeGetVersion(), 1U);
+
+    // Unload
+    UnloadNativeBridge();
+
+    // Version information is gone.
+    EXPECT_EQ(NativeBridgeGetVersion(), 0U);
+}
+
+}  // namespace android