488 lines
16 KiB
C++
488 lines
16 KiB
C++
/*
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* Copyright (C) 2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include "nativebridge/native_bridge.h"
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#include <cstring>
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#include <cutils/log.h>
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#include <dlfcn.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <sys/mount.h>
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#include <sys/stat.h>
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namespace android {
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// Environment values required by the apps running with native bridge.
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struct NativeBridgeRuntimeValues {
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const char* os_arch;
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const char* cpu_abi;
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const char* cpu_abi2;
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const char* *supported_abis;
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int32_t abi_count;
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};
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// The symbol name exposed by native-bridge with the type of NativeBridgeCallbacks.
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static constexpr const char* kNativeBridgeInterfaceSymbol = "NativeBridgeItf";
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enum class NativeBridgeState {
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kNotSetup, // Initial state.
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kOpened, // After successful dlopen.
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kPreInitialized, // After successful pre-initialization.
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kInitialized, // After successful initialization.
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kClosed // Closed or errors.
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};
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static constexpr const char* kNotSetupString = "kNotSetup";
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static constexpr const char* kOpenedString = "kOpened";
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static constexpr const char* kPreInitializedString = "kPreInitialized";
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static constexpr const char* kInitializedString = "kInitialized";
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static constexpr const char* kClosedString = "kClosed";
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static const char* GetNativeBridgeStateString(NativeBridgeState state) {
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switch (state) {
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case NativeBridgeState::kNotSetup:
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return kNotSetupString;
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case NativeBridgeState::kOpened:
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return kOpenedString;
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case NativeBridgeState::kPreInitialized:
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return kPreInitializedString;
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case NativeBridgeState::kInitialized:
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return kInitializedString;
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case NativeBridgeState::kClosed:
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return kClosedString;
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}
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}
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// Current state of the native bridge.
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static NativeBridgeState state = NativeBridgeState::kNotSetup;
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// Whether we had an error at some point.
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static bool had_error = false;
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// Handle of the loaded library.
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static void* native_bridge_handle = nullptr;
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// Pointer to the callbacks. Available as soon as LoadNativeBridge succeeds, but only initialized
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// later.
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static NativeBridgeCallbacks* callbacks = nullptr;
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// Callbacks provided by the environment to the bridge. Passed to LoadNativeBridge.
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static const NativeBridgeRuntimeCallbacks* runtime_callbacks = nullptr;
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// The app's code cache directory.
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static char* app_code_cache_dir = nullptr;
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// Code cache directory (relative to the application private directory)
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// Ideally we'd like to call into framework to retrieve this name. However that's considered an
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// implementation detail and will require either hacks or consistent refactorings. We compromise
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// and hard code the directory name again here.
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static constexpr const char* kCodeCacheDir = "code_cache";
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static constexpr uint32_t kNativeBridgeCallbackVersion = 1;
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// Characters allowed in a native bridge filename. The first character must
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// be in [a-zA-Z] (expected 'l' for "libx"). The rest must be in [a-zA-Z0-9._-].
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static bool CharacterAllowed(char c, bool first) {
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if (first) {
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return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z');
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} else {
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return ('a' <= c && c <= 'z') || ('A' <= c && c <= 'Z') || ('0' <= c && c <= '9') ||
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(c == '.') || (c == '_') || (c == '-');
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}
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}
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// We only allow simple names for the library. It is supposed to be a file in
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// /system/lib or /vendor/lib. Only allow a small range of characters, that is
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// names consisting of [a-zA-Z0-9._-] and starting with [a-zA-Z].
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bool NativeBridgeNameAcceptable(const char* nb_library_filename) {
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const char* ptr = nb_library_filename;
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if (*ptr == 0) {
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// Emptry string. Allowed, means no native bridge.
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return true;
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} else {
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// First character must be [a-zA-Z].
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if (!CharacterAllowed(*ptr, true)) {
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// Found an invalid fist character, don't accept.
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ALOGE("Native bridge library %s has been rejected for first character %c", nb_library_filename, *ptr);
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return false;
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} else {
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// For the rest, be more liberal.
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ptr++;
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while (*ptr != 0) {
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if (!CharacterAllowed(*ptr, false)) {
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// Found an invalid character, don't accept.
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ALOGE("Native bridge library %s has been rejected for %c", nb_library_filename, *ptr);
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return false;
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}
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ptr++;
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}
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}
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return true;
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}
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}
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static bool VersionCheck(NativeBridgeCallbacks* cb) {
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return cb != nullptr && cb->version == kNativeBridgeCallbackVersion;
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}
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static void CloseNativeBridge(bool with_error) {
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state = NativeBridgeState::kClosed;
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had_error |= with_error;
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delete[] app_code_cache_dir;
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app_code_cache_dir = nullptr;
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}
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bool LoadNativeBridge(const char* nb_library_filename,
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const NativeBridgeRuntimeCallbacks* runtime_cbs) {
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// We expect only one place that calls LoadNativeBridge: Runtime::Init. At that point we are not
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// multi-threaded, so we do not need locking here.
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if (state != NativeBridgeState::kNotSetup) {
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// Setup has been called before. Ignore this call.
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if (nb_library_filename != nullptr) { // Avoids some log-spam for dalvikvm.
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ALOGW("Called LoadNativeBridge for an already set up native bridge. State is %s.",
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GetNativeBridgeStateString(state));
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}
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// Note: counts as an error, even though the bridge may be functional.
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had_error = true;
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return false;
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}
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if (nb_library_filename == nullptr || *nb_library_filename == 0) {
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CloseNativeBridge(false);
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return false;
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} else {
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if (!NativeBridgeNameAcceptable(nb_library_filename)) {
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CloseNativeBridge(true);
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} else {
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// Try to open the library.
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void* handle = dlopen(nb_library_filename, RTLD_LAZY);
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if (handle != nullptr) {
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callbacks = reinterpret_cast<NativeBridgeCallbacks*>(dlsym(handle,
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kNativeBridgeInterfaceSymbol));
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if (callbacks != nullptr) {
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if (VersionCheck(callbacks)) {
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// Store the handle for later.
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native_bridge_handle = handle;
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} else {
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callbacks = nullptr;
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dlclose(handle);
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ALOGW("Unsupported native bridge interface.");
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}
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} else {
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dlclose(handle);
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}
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}
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// Two failure conditions: could not find library (dlopen failed), or could not find native
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// bridge interface (dlsym failed). Both are an error and close the native bridge.
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if (callbacks == nullptr) {
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CloseNativeBridge(true);
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} else {
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runtime_callbacks = runtime_cbs;
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state = NativeBridgeState::kOpened;
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}
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}
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return state == NativeBridgeState::kOpened;
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}
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}
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#if defined(__arm__)
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static const char* kRuntimeISA = "arm";
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#elif defined(__aarch64__)
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static const char* kRuntimeISA = "arm64";
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#elif defined(__mips__)
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static const char* kRuntimeISA = "mips";
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#elif defined(__i386__)
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static const char* kRuntimeISA = "x86";
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#elif defined(__x86_64__)
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static const char* kRuntimeISA = "x86_64";
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#else
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static const char* kRuntimeISA = "unknown";
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#endif
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bool NeedsNativeBridge(const char* instruction_set) {
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if (instruction_set == nullptr) {
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ALOGE("Null instruction set in NeedsNativeBridge.");
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return false;
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}
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return strncmp(instruction_set, kRuntimeISA, strlen(kRuntimeISA) + 1) != 0;
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}
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#ifdef __APPLE__
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template<typename T> void UNUSED(const T&) {}
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#endif
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bool PreInitializeNativeBridge(const char* app_data_dir_in, const char* instruction_set) {
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if (state != NativeBridgeState::kOpened) {
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ALOGE("Invalid state: native bridge is expected to be opened.");
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CloseNativeBridge(true);
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return false;
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}
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if (app_data_dir_in == nullptr) {
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ALOGE("Application private directory cannot be null.");
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CloseNativeBridge(true);
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return false;
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}
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// Create the path to the application code cache directory.
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// The memory will be release after Initialization or when the native bridge is closed.
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const size_t len = strlen(app_data_dir_in) + strlen(kCodeCacheDir) + 2; // '\0' + '/'
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app_code_cache_dir = new char[len];
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snprintf(app_code_cache_dir, len, "%s/%s", app_data_dir_in, kCodeCacheDir);
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// Bind-mount /system/lib{,64}/<isa>/cpuinfo to /proc/cpuinfo.
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// Failure is not fatal and will keep the native bridge in kPreInitialized.
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state = NativeBridgeState::kPreInitialized;
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#ifndef __APPLE__
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if (instruction_set == nullptr) {
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return true;
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}
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size_t isa_len = strlen(instruction_set);
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if (isa_len > 10) {
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// 10 is a loose upper bound on the currently known instruction sets (a tight bound is 7 for
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// x86_64 [including the trailing \0]). This is so we don't have to change here if there will
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// be another instruction set in the future.
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ALOGW("Instruction set %s is malformed, must be less than or equal to 10 characters.",
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instruction_set);
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return true;
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}
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// If the file does not exist, the mount command will fail,
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// so we save the extra file existence check.
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char cpuinfo_path[1024];
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#ifdef HAVE_ANDROID_OS
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snprintf(cpuinfo_path, sizeof(cpuinfo_path), "/system/lib"
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#ifdef __LP64__
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"64"
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#endif // __LP64__
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"/%s/cpuinfo", instruction_set);
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#else // !HAVE_ANDROID_OS
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// To be able to test on the host, we hardwire a relative path.
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snprintf(cpuinfo_path, sizeof(cpuinfo_path), "./cpuinfo");
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#endif
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// Bind-mount.
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if (TEMP_FAILURE_RETRY(mount(cpuinfo_path, // Source.
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"/proc/cpuinfo", // Target.
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nullptr, // FS type.
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MS_BIND, // Mount flags: bind mount.
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nullptr)) == -1) { // "Data."
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ALOGW("Failed to bind-mount %s as /proc/cpuinfo: %s", cpuinfo_path, strerror(errno));
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}
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#else // __APPLE__
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UNUSED(instruction_set);
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ALOGW("Mac OS does not support bind-mounting. Host simulation of native bridge impossible.");
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#endif
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return true;
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}
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static void SetCpuAbi(JNIEnv* env, jclass build_class, const char* field, const char* value) {
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if (value != nullptr) {
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jfieldID field_id = env->GetStaticFieldID(build_class, field, "Ljava/lang/String;");
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if (field_id == nullptr) {
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env->ExceptionClear();
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ALOGW("Could not find %s field.", field);
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return;
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}
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jstring str = env->NewStringUTF(value);
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if (str == nullptr) {
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env->ExceptionClear();
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ALOGW("Could not create string %s.", value);
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return;
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}
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env->SetStaticObjectField(build_class, field_id, str);
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}
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}
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// Set up the environment for the bridged app.
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static void SetupEnvironment(NativeBridgeCallbacks* callbacks, JNIEnv* env, const char* isa) {
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// Need a JNIEnv* to do anything.
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if (env == nullptr) {
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ALOGW("No JNIEnv* to set up app environment.");
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return;
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}
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// Query the bridge for environment values.
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const struct NativeBridgeRuntimeValues* env_values = callbacks->getAppEnv(isa);
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if (env_values == nullptr) {
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return;
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}
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// Keep the JNIEnv clean.
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jint success = env->PushLocalFrame(16); // That should be small and large enough.
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if (success < 0) {
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// Out of memory, really borked.
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ALOGW("Out of memory while setting up app environment.");
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env->ExceptionClear();
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return;
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}
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// Reset CPU_ABI & CPU_ABI2 to values required by the apps running with native bridge.
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if (env_values->cpu_abi != nullptr || env_values->cpu_abi2 != nullptr ||
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env_values->abi_count >= 0) {
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jclass bclass_id = env->FindClass("android/os/Build");
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if (bclass_id != nullptr) {
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SetCpuAbi(env, bclass_id, "CPU_ABI", env_values->cpu_abi);
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SetCpuAbi(env, bclass_id, "CPU_ABI2", env_values->cpu_abi2);
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} else {
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// For example in a host test environment.
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env->ExceptionClear();
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ALOGW("Could not find Build class.");
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}
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}
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if (env_values->os_arch != nullptr) {
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jclass sclass_id = env->FindClass("java/lang/System");
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if (sclass_id != nullptr) {
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jmethodID set_prop_id = env->GetStaticMethodID(sclass_id, "initUnchangeableSystemProperty",
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"(Ljava/lang/String;Ljava/lang/String;)V");
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if (set_prop_id != nullptr) {
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// Init os.arch to the value reqired by the apps running with native bridge.
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env->CallStaticVoidMethod(sclass_id, set_prop_id, env->NewStringUTF("os.arch"),
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env->NewStringUTF(env_values->os_arch));
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} else {
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env->ExceptionClear();
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ALOGW("Could not find initUnchangeableSystemProperty method.");
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}
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} else {
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env->ExceptionClear();
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ALOGW("Could not find System class.");
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}
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}
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// Make it pristine again.
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env->PopLocalFrame(nullptr);
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}
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bool InitializeNativeBridge(JNIEnv* env, const char* instruction_set) {
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// We expect only one place that calls InitializeNativeBridge: Runtime::DidForkFromZygote. At that
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// point we are not multi-threaded, so we do not need locking here.
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if (state == NativeBridgeState::kPreInitialized) {
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// Check for code cache: if it doesn't exist try to create it.
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struct stat st;
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if (stat(app_code_cache_dir, &st) == -1) {
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if (errno == ENOENT) {
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if (mkdir(app_code_cache_dir, S_IRWXU | S_IRWXG | S_IXOTH) == -1) {
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ALOGE("Cannot create code cache directory %s: %s.", app_code_cache_dir, strerror(errno));
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CloseNativeBridge(true);
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}
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} else {
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ALOGE("Cannot stat code cache directory %s: %s.", app_code_cache_dir, strerror(errno));
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CloseNativeBridge(true);
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}
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} else if (!S_ISDIR(st.st_mode)) {
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ALOGE("Code cache is not a directory %s.", app_code_cache_dir);
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CloseNativeBridge(true);
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}
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// If we're still PreInitialized (dind't fail the code cache checks) try to initialize.
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if (state == NativeBridgeState::kPreInitialized) {
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if (callbacks->initialize(runtime_callbacks, app_code_cache_dir, instruction_set)) {
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SetupEnvironment(callbacks, env, instruction_set);
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state = NativeBridgeState::kInitialized;
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// We no longer need the code cache path, release the memory.
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delete[] app_code_cache_dir;
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app_code_cache_dir = nullptr;
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} else {
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// Unload the library.
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dlclose(native_bridge_handle);
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CloseNativeBridge(true);
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}
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}
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} else {
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CloseNativeBridge(true);
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}
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return state == NativeBridgeState::kInitialized;
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}
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void UnloadNativeBridge() {
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// We expect only one place that calls UnloadNativeBridge: Runtime::DidForkFromZygote. At that
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// point we are not multi-threaded, so we do not need locking here.
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switch(state) {
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case NativeBridgeState::kOpened:
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case NativeBridgeState::kPreInitialized:
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case NativeBridgeState::kInitialized:
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// Unload.
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dlclose(native_bridge_handle);
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CloseNativeBridge(false);
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break;
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case NativeBridgeState::kNotSetup:
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// Not even set up. Error.
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CloseNativeBridge(true);
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break;
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case NativeBridgeState::kClosed:
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// Ignore.
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break;
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}
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}
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bool NativeBridgeError() {
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return had_error;
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}
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bool NativeBridgeAvailable() {
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return state == NativeBridgeState::kOpened
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|| state == NativeBridgeState::kPreInitialized
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|| state == NativeBridgeState::kInitialized;
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}
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bool NativeBridgeInitialized() {
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// Calls of this are supposed to happen in a state where the native bridge is stable, i.e., after
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// Runtime::DidForkFromZygote. In that case we do not need a lock.
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return state == NativeBridgeState::kInitialized;
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}
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void* NativeBridgeLoadLibrary(const char* libpath, int flag) {
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if (NativeBridgeInitialized()) {
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return callbacks->loadLibrary(libpath, flag);
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}
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return nullptr;
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}
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void* NativeBridgeGetTrampoline(void* handle, const char* name, const char* shorty,
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uint32_t len) {
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if (NativeBridgeInitialized()) {
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return callbacks->getTrampoline(handle, name, shorty, len);
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}
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return nullptr;
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}
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bool NativeBridgeIsSupported(const char* libpath) {
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if (NativeBridgeInitialized()) {
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return callbacks->isSupported(libpath);
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}
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return false;
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}
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}; // namespace android
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