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/*
* Copyright (C) 2016 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 "core_jni_helpers.h"
#include <cutils/ashmem.h>
#include <linux/ashmem.h>
#include <sys/mman.h>
namespace android {
static jint android_util_MemoryIntArray_create(JNIEnv* env, jobject clazz, jstring name,
jint size)
{
if (name == NULL) {
jniThrowException(env, "java/io/IOException", "bad name");
return -1;
}
if (size <= 0) {
jniThrowException(env, "java/io/IOException", "bad size");
return -1;
}
const char* nameStr = env->GetStringUTFChars(name, NULL);
const int ashmemSize = sizeof(std::atomic_int) * size;
int fd = ashmem_create_region(nameStr, ashmemSize);
env->ReleaseStringUTFChars(name, nameStr);
if (fd < 0) {
jniThrowException(env, "java/io/IOException", "ashmem creation failed");
return -1;
}
int setProtResult = ashmem_set_prot_region(fd, PROT_READ | PROT_WRITE);
if (setProtResult < 0) {
jniThrowException(env, "java/io/IOException", "cannot set ashmem prot mode");
return -1;
}
return fd;
}
static jlong android_util_MemoryIntArray_open(JNIEnv* env, jobject clazz, jint fd,
jboolean owner)
{
if (fd < 0) {
jniThrowException(env, "java/io/IOException", "bad file descriptor");
return -1;
}
int ashmemSize = ashmem_get_size_region(fd);
if (ashmemSize <= 0) {
jniThrowException(env, "java/io/IOException", "bad ashmem size");
return -1;
}
// IMPORTANT: Ashmem allows the caller to change its size until
// it is memory mapped for the first time which lazily creates
// the underlying VFS file. So the size we get above may not
// reflect the size of the underlying shared memory region. Therefore,
// we first memory map to set the size in stone an verify if
// the underlying ashmem region has the same size as the one we
// memory mapped. This is critical as we use the underlying
// ashmem size for boundary checks and memory unmapping.
int protMode = owner ? (PROT_READ | PROT_WRITE) : PROT_READ;
void* ashmemAddr = mmap(NULL, ashmemSize, protMode, MAP_SHARED, fd, 0);
if (ashmemAddr == MAP_FAILED) {
jniThrowException(env, "java/io/IOException", "cannot mmap ashmem");
return -1;
}
// Check if the mapped size is the same as the ashmem region.
int mmapedSize = ashmem_get_size_region(fd);
if (mmapedSize != ashmemSize) {
munmap(reinterpret_cast<void *>(ashmemAddr), ashmemSize);
jniThrowException(env, "java/io/IOException", "bad file descriptor");
return -1;
}
if (owner) {
int size = ashmemSize / sizeof(std::atomic_int);
new (ashmemAddr) std::atomic_int[size];
}
if (owner) {
int setProtResult = ashmem_set_prot_region(fd, PROT_READ);
if (setProtResult < 0) {
jniThrowException(env, "java/io/IOException", "cannot set ashmem prot mode");
return -1;
}
}
return reinterpret_cast<jlong>(ashmemAddr);
}
static void android_util_MemoryIntArray_close(JNIEnv* env, jobject clazz, jint fd,
jlong ashmemAddr, jboolean owner)
{
if (fd < 0) {
jniThrowException(env, "java/io/IOException", "bad file descriptor");
return;
}
int ashmemSize = ashmem_get_size_region(fd);
if (ashmemSize <= 0) {
jniThrowException(env, "java/io/IOException", "bad ashmem size");
return;
}
int unmapResult = munmap(reinterpret_cast<void *>(ashmemAddr), ashmemSize);
if (unmapResult < 0) {
jniThrowException(env, "java/io/IOException", "munmap failed");
return;
}
// We don't deallocate the atomic ints we created with placement new in the ashmem
// region as the kernel we reclaim all pages when the ashmem region is destroyed.
if (owner && (ashmem_unpin_region(fd, 0, 0) != ASHMEM_IS_UNPINNED)) {
jniThrowException(env, "java/io/IOException", "ashmem unpinning failed");
return;
}
close(fd);
}
static jint android_util_MemoryIntArray_get(JNIEnv* env, jobject clazz,
jint fd, jlong address, jint index)
{
if (fd < 0) {
jniThrowException(env, "java/io/IOException", "bad file descriptor");
return -1;
}
if (ashmem_pin_region(fd, 0, 0) == ASHMEM_WAS_PURGED) {
jniThrowException(env, "java/io/IOException", "ashmem region was purged");
return -1;
}
std::atomic_int* value = reinterpret_cast<std::atomic_int*>(address) + index;
return value->load(std::memory_order_relaxed);
}
static void android_util_MemoryIntArray_set(JNIEnv* env, jobject clazz,
jint fd, jlong address, jint index, jint newValue)
{
if (fd < 0) {
jniThrowException(env, "java/io/IOException", "bad file descriptor");
return;
}
if (ashmem_pin_region(fd, 0, 0) == ASHMEM_WAS_PURGED) {
jniThrowException(env, "java/io/IOException", "ashmem region was purged");
return;
}
std::atomic_int* value = reinterpret_cast<std::atomic_int*>(address) + index;
value->store(newValue, std::memory_order_relaxed);
}
static jint android_util_MemoryIntArray_size(JNIEnv* env, jobject clazz, jint fd) {
if (fd < 0) {
jniThrowException(env, "java/io/IOException", "bad file descriptor");
return -1;
}
int ashmemSize = ashmem_get_size_region(fd);
if (ashmemSize < 0) {
// Some other error, throw exception
jniThrowIOException(env, errno);
return -1;
}
return ashmemSize / sizeof(std::atomic_int);
}
static const JNINativeMethod methods[] = {
{"nativeCreate", "(Ljava/lang/String;I)I", (void*)android_util_MemoryIntArray_create},
{"nativeOpen", "(IZ)J", (void*)android_util_MemoryIntArray_open},
{"nativeClose", "(IJZ)V", (void*)android_util_MemoryIntArray_close},
{"nativeGet", "(IJI)I", (void*)android_util_MemoryIntArray_get},
{"nativeSet", "(IJII)V", (void*) android_util_MemoryIntArray_set},
{"nativeSize", "(I)I", (void*) android_util_MemoryIntArray_size},
};
int register_android_util_MemoryIntArray(JNIEnv* env)
{
return RegisterMethodsOrDie(env, "android/util/MemoryIntArray", methods, NELEM(methods));
}
}
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