/*
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* Copyright (C) 2017 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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#define LOG_TAG "SharedMemory"
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#include "core_jni_helpers.h"
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#include <cutils/ashmem.h>
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#include <utils/Log.h>
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#include <nativehelper/jni_macros.h>
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#include <nativehelper/JNIHelp.h>
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#include <nativehelper/ScopedLocalRef.h>
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#include <algorithm>
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#include <errno.h>
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#include <limits>
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#include <unistd.h>
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namespace {
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jclass errnoExceptionClass;
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jmethodID errnoExceptionCtor; // MethodID for ErrnoException.<init>(String,I)
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void throwErrnoException(JNIEnv* env, const char* functionName, int error) {
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ScopedLocalRef<jstring> detailMessage(env, env->NewStringUTF(functionName));
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if (detailMessage.get() == NULL) {
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// Not really much we can do here. We're probably dead in the water,
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// but let's try to stumble on...
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env->ExceptionClear();
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}
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jobject exception = env->NewObject(errnoExceptionClass,
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errnoExceptionCtor,
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detailMessage.get(),
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error);
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env->Throw(reinterpret_cast<jthrowable>(exception));
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}
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jobject SharedMemory_nCreate(JNIEnv* env, jobject, jstring jname, jint size) {
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// Name is optional so we can't use ScopedUtfChars for this as it throws NPE on null
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const char* name = jname ? env->GetStringUTFChars(jname, nullptr) : nullptr;
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int fd = ashmem_create_region(name, size);
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// Capture the error, if there is one, before calling ReleaseStringUTFChars
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int err = fd < 0 ? errno : 0;
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if (name) {
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env->ReleaseStringUTFChars(jname, name);
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}
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if (fd < 0) {
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throwErrnoException(env, "SharedMemory_create", err);
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return nullptr;
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}
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return jniCreateFileDescriptor(env, fd);
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}
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jint SharedMemory_nGetSize(JNIEnv* env, jobject, jobject fileDescriptor) {
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int fd = jniGetFDFromFileDescriptor(env, fileDescriptor);
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if (!ashmem_valid(fd)) {
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return -1;
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}
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size_t size = ashmem_get_size_region(fd);
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return static_cast<jint>(std::min(size, static_cast<size_t>(std::numeric_limits<jint>::max())));
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}
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jint SharedMemory_nSetProt(JNIEnv* env, jobject, jobject fileDescriptor, jint prot) {
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int fd = jniGetFDFromFileDescriptor(env, fileDescriptor);
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int err = 0;
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if (ashmem_set_prot_region(fd, prot)) {
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err = errno;
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}
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return err;
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}
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const JNINativeMethod methods[] = {
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NATIVE_METHOD(SharedMemory, nCreate, "(Ljava/lang/String;I)Ljava/io/FileDescriptor;"),
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NATIVE_METHOD(SharedMemory, nGetSize, "(Ljava/io/FileDescriptor;)I"),
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NATIVE_METHOD(SharedMemory, nSetProt, "(Ljava/io/FileDescriptor;I)I")
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};
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} // anonymous namespace
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namespace android {
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int register_android_os_SharedMemory(JNIEnv* env) {
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errnoExceptionClass =
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MakeGlobalRefOrDie(env, FindClassOrDie(env, "android/system/ErrnoException"));
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errnoExceptionCtor =
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GetMethodIDOrDie(env, errnoExceptionClass, "<init>", "(Ljava/lang/String;I)V");
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return RegisterMethodsOrDie(env, "android/os/SharedMemory", methods, NELEM(methods));
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}
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} // namespace android
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