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