1/*
2 * Copyright (C) 2017 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#include <jni.h>
18
19#include <android/sharedmem.h>
20#include <android/sharedmem_jni.h>
21#include <cutils/ashmem.h>
22#include <log/log.h>
23#include <utils/Errors.h>
24
25#include <mutex>
26#include <unistd.h>
27
28static struct {
29    jclass clazz;
30    jmethodID getFd;
31} sSharedMemory;
32
33static void jniInit(JNIEnv* env) {
34    static std::once_flag sJniInitialized;
35    std::call_once(sJniInitialized, [](JNIEnv* env) {
36        jclass clazz = env->FindClass("android/os/SharedMemory");
37        LOG_ALWAYS_FATAL_IF(clazz == nullptr, "Failed to find android.os.SharedMemory");
38        sSharedMemory.clazz = (jclass) env->NewGlobalRef(clazz);
39        LOG_ALWAYS_FATAL_IF(sSharedMemory.clazz == nullptr,
40                "Failed to create global ref of android.os.SharedMemory");
41        sSharedMemory.getFd = env->GetMethodID(sSharedMemory.clazz, "getFd", "()I");
42        LOG_ALWAYS_FATAL_IF(sSharedMemory.getFd == nullptr,
43                "Failed to find method SharedMemory#getFd()");
44    }, env);
45}
46
47int ASharedMemory_create(const char *name, size_t size) {
48    if (size == 0) {
49        return android::BAD_VALUE;
50    }
51    return ashmem_create_region(name, size);
52}
53
54size_t ASharedMemory_getSize(int fd) {
55    return ashmem_valid(fd) ? ashmem_get_size_region(fd) : 0;
56}
57
58int ASharedMemory_setProt(int fd, int prot) {
59    return ashmem_set_prot_region(fd, prot);
60}
61
62int ASharedMemory_dupFromJava(JNIEnv* env, jobject javaSharedMemory) {
63    if (env == nullptr || javaSharedMemory == nullptr) {
64        return -1;
65    }
66    jniInit(env);
67    if (!env->IsInstanceOf(javaSharedMemory, sSharedMemory.clazz)) {
68        ALOGW("ASharedMemory_dupFromJava called with object "
69                "that's not an instanceof android.os.SharedMemory");
70        return -1;
71    }
72    int fd = env->CallIntMethod(javaSharedMemory, sSharedMemory.getFd);
73    if (fd != -1) {
74        fd = dup(fd);
75    }
76    return fd;
77}
78