android_util_MemoryIntArray.cpp revision 24c27754c5f1d23dfa679ade368977936519a58d 
1/*
2 * Copyright (C) 2016 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 "core_jni_helpers.h"
18#include <cutils/ashmem.h>
19#include <linux/ashmem.h>
20#include <sys/mman.h>
21
22namespace android {
23
24static jint android_util_MemoryIntArray_create(JNIEnv* env, jobject clazz, jstring name,
25        jint size)
26{
27    if (name == NULL) {
28        jniThrowException(env, "java/io/IOException", "bad name");
29        return -1;
30    }
31
32    if (size <= 0) {
33        jniThrowException(env, "java/io/IOException", "bad size");
34        return -1;
35    }
36
37    const char* nameStr = env->GetStringUTFChars(name, NULL);
38    const int ashmemSize = sizeof(std::atomic_int) * size;
39    int fd = ashmem_create_region(nameStr, ashmemSize);
40    env->ReleaseStringUTFChars(name, nameStr);
41
42    if (fd < 0) {
43        jniThrowException(env, "java/io/IOException", "ashmem creation failed");
44        return -1;
45    }
46
47    int setProtResult = ashmem_set_prot_region(fd, PROT_READ | PROT_WRITE);
48    if (setProtResult < 0) {
49        jniThrowException(env, "java/io/IOException", "cannot set ashmem prot mode");
50        return -1;
51    }
52
53    return fd;
54}
55
56static jlong android_util_MemoryIntArray_open(JNIEnv* env, jobject clazz, jint fd,
57    jboolean owner, jboolean writable)
58{
59    if (fd < 0) {
60        jniThrowException(env, "java/io/IOException", "bad file descriptor");
61        return -1;
62    }
63
64    if (!ashmem_valid(fd)) {
65        jniThrowIOException(env, errno);
66        return -1;
67    }
68
69    int ashmemSize = ashmem_get_size_region(fd);
70    if (ashmemSize <= 0) {
71        jniThrowException(env, "java/io/IOException", "bad ashmem size");
72        return -1;
73    }
74
75    int protMode = (owner || writable) ? (PROT_READ | PROT_WRITE) : PROT_READ;
76    void* ashmemAddr = mmap(NULL, ashmemSize, protMode, MAP_SHARED, fd, 0);
77    if (ashmemAddr == MAP_FAILED) {
78        jniThrowException(env, "java/io/IOException", "cannot mmap ashmem");
79        return -1;
80    }
81
82    if (owner) {
83        int size = ashmemSize / sizeof(std::atomic_int);
84        new (ashmemAddr) std::atomic_int[size];
85    }
86
87    if (owner && !writable) {
88        int setProtResult = ashmem_set_prot_region(fd, PROT_READ);
89        if (setProtResult < 0) {
90            jniThrowException(env, "java/io/IOException", "cannot set ashmem prot mode");
91            return -1;
92        }
93    }
94
95    return reinterpret_cast<jlong>(ashmemAddr);
96}
97
98static void android_util_MemoryIntArray_close(JNIEnv* env, jobject clazz, jint fd,
99    jlong ashmemAddr, jboolean owner)
100{
101    if (fd < 0) {
102        jniThrowException(env, "java/io/IOException", "bad file descriptor");
103        return;
104    }
105
106    if (!ashmem_valid(fd)) {
107        jniThrowIOException(env, errno);
108        return;
109    }
110
111    int ashmemSize = ashmem_get_size_region(fd);
112    if (ashmemSize <= 0) {
113        jniThrowException(env, "java/io/IOException", "bad ashmem size");
114        return;
115    }
116
117    int unmapResult = munmap(reinterpret_cast<void *>(ashmemAddr), ashmemSize);
118    if (unmapResult < 0) {
119        jniThrowException(env, "java/io/IOException", "munmap failed");
120        return;
121    }
122
123    // We don't deallocate the atomic ints we created with placement new in the ashmem
124    // region as the kernel we reclaim all pages when the ashmem region is destroyed.
125    if (owner && (ashmem_unpin_region(fd, 0, 0) != ASHMEM_IS_UNPINNED)) {
126        jniThrowException(env, "java/io/IOException", "ashmem unpinning failed");
127        return;
128    }
129
130    close(fd);
131}
132
133static jint android_util_MemoryIntArray_get(JNIEnv* env, jobject clazz,
134        jint fd, jlong address, jint index, jboolean owner)
135{
136    if (fd < 0) {
137        jniThrowException(env, "java/io/IOException", "bad file descriptor");
138        return -1;
139    }
140
141    if (!ashmem_valid(fd)) {
142        jniThrowIOException(env, errno);
143        return -1;
144    }
145
146    if (ashmem_pin_region(fd, 0, 0) == ASHMEM_WAS_PURGED) {
147        jniThrowException(env, "java/io/IOException", "ashmem region was purged");
148        return -1;
149    }
150
151    std::atomic_int* value = reinterpret_cast<std::atomic_int*>(address) + index;
152    return value->load(std::memory_order_relaxed);
153}
154
155static void android_util_MemoryIntArray_set(JNIEnv* env, jobject clazz,
156        jint fd, jlong address, jint index, jint newValue, jboolean owner)
157{
158    if (fd < 0) {
159        jniThrowException(env, "java/io/IOException", "bad file descriptor");
160        return;
161    }
162
163    if (!ashmem_valid(fd)) {
164        jniThrowIOException(env, errno);
165        return;
166    }
167
168    if (ashmem_pin_region(fd, 0, 0) == ASHMEM_WAS_PURGED) {
169        jniThrowException(env, "java/io/IOException", "ashmem region was purged");
170        return;
171    }
172
173    std::atomic_int* value = reinterpret_cast<std::atomic_int*>(address) + index;
174    value->store(newValue, std::memory_order_relaxed);
175}
176
177static jint android_util_MemoryIntArray_size(JNIEnv* env, jobject clazz, jint fd) {
178    if (fd < 0) {
179        jniThrowException(env, "java/io/IOException", "bad file descriptor");
180        return -1;
181    }
182
183    if (!ashmem_valid(fd)) {
184        jniThrowIOException(env, errno);
185        return -1;
186    }
187
188    int ashmemSize = ashmem_get_size_region(fd);
189    if (ashmemSize < 0) {
190        jniThrowIOException(env, errno);
191        return -1;
192    }
193    return ashmemSize / sizeof(std::atomic_int);
194}
195
196static const JNINativeMethod methods[] = {
197    {"nativeCreate",  "(Ljava/lang/String;I)I", (void*)android_util_MemoryIntArray_create},
198    {"nativeOpen",  "(IZZ)J", (void*)android_util_MemoryIntArray_open},
199    {"nativeClose", "(IJZ)V", (void*)android_util_MemoryIntArray_close},
200    {"nativeGet",  "(IJIZ)I", (void*)android_util_MemoryIntArray_get},
201    {"nativeSet", "(IJIIZ)V", (void*) android_util_MemoryIntArray_set},
202    {"nativeSize", "(I)I", (void*) android_util_MemoryIntArray_size},
203};
204
205int register_android_util_MemoryIntArray(JNIEnv* env)
206{
207    return RegisterMethodsOrDie(env, "android/util/MemoryIntArray", methods, NELEM(methods));
208}
209
210}
211