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
27 namespace android {
28
android_os_MemoryFile_pin(JNIEnv * env,jobject clazz,jobject fileDescriptor,jboolean pin)29 static 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
android_os_MemoryFile_get_size(JNIEnv * env,jobject clazz,jobject fileDescriptor)39 static 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
59 static 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
register_android_os_MemoryFile(JNIEnv * env)65 int register_android_os_MemoryFile(JNIEnv* env) {
66 return RegisterMethodsOrDie(env, "android/os/MemoryFile", methods, NELEM(methods));
67 }
68
69 }
70