1/*
2 * Copyright (C) 2008 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#define LOG_TAG "MemoryFile"
18#include <utils/Log.h>
19
20#include <cutils/ashmem.h>
21#include "core_jni_helpers.h"
22#include <nativehelper/JNIHelp.h>
23#include <unistd.h>
24#include <sys/mman.h>
25
26
27namespace android {
28
29static jboolean android_os_MemoryFile_pin(JNIEnv* env, jobject clazz, jobject fileDescriptor,
30        jboolean pin) {
31    int fd = jniGetFDFromFileDescriptor(env, fileDescriptor);
32    int result = (pin ? ashmem_pin_region(fd, 0, 0) : ashmem_unpin_region(fd, 0, 0));
33    if (result < 0) {
34        jniThrowException(env, "java/io/IOException", NULL);
35    }
36    return result == ASHMEM_WAS_PURGED;
37}
38
39static jint android_os_MemoryFile_get_size(JNIEnv* env, jobject clazz,
40        jobject fileDescriptor) {
41    int fd = jniGetFDFromFileDescriptor(env, fileDescriptor);
42    // Use ASHMEM_GET_SIZE to find out if the fd refers to an ashmem region.
43    // ASHMEM_GET_SIZE should succeed for all ashmem regions, and the kernel
44    // should return ENOTTY for all other valid file descriptors
45    int result = ashmem_get_size_region(fd);
46    if (result < 0) {
47        if (errno == ENOTTY) {
48            // ENOTTY means that the ioctl does not apply to this object,
49            // i.e., it is not an ashmem region.
50            return (jint) -1;
51        }
52        // Some other error, throw exception
53        jniThrowIOException(env, errno);
54        return (jint) -1;
55    }
56    return (jint) result;
57}
58
59static const JNINativeMethod methods[] = {
60    {"native_pin",   "(Ljava/io/FileDescriptor;Z)Z", (void*)android_os_MemoryFile_pin},
61    {"native_get_size", "(Ljava/io/FileDescriptor;)I",
62            (void*)android_os_MemoryFile_get_size}
63};
64
65int register_android_os_MemoryFile(JNIEnv* env) {
66    return RegisterMethodsOrDie(env, "android/os/MemoryFile", methods, NELEM(methods));
67}
68
69}
70