android_os_MemoryFile.cpp revision 761e0918d30b6a3f292625b44b86dffd1538bc78 
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 <android_runtime/AndroidRuntime.h>
22#include "JNIHelp.h"
23#include <unistd.h>
24#include <sys/mman.h>
25
26
27namespace android {
28
29static jobject android_os_MemoryFile_open(JNIEnv* env, jobject clazz, jstring name, jint length)
30{
31    const char* namestr = (name ? env->GetStringUTFChars(name, NULL) : NULL);
32
33    // round up length to page boundary
34    length = (((length - 1) / getpagesize()) + 1) * getpagesize();
35    int result = ashmem_create_region(namestr, length);
36
37    if (name)
38        env->ReleaseStringUTFChars(name, namestr);
39
40    if (result < 0) {
41        jniThrowException(env, "java/io/IOException", "ashmem_create_region failed");
42	return NULL;
43    }
44
45    return jniCreateFileDescriptor(env, result);
46}
47
48static jint android_os_MemoryFile_mmap(JNIEnv* env, jobject clazz, jobject fileDescriptor,
49        jint length)
50{
51    int fd = jniGetFDFromFileDescriptor(env, fileDescriptor);
52    jint result = (jint)mmap(NULL, length, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
53    if (!result)
54        jniThrowException(env, "java/io/IOException", "mmap failed");
55    return result;
56}
57
58static void android_os_MemoryFile_munmap(JNIEnv* env, jobject clazz, jint addr, jint length)
59{
60    int result = munmap((void *)addr, length);
61    if (result < 0)
62        jniThrowException(env, "java/io/IOException", "munmap failed");
63}
64
65static void android_os_MemoryFile_close(JNIEnv* env, jobject clazz, jobject fileDescriptor)
66{
67    int fd = jniGetFDFromFileDescriptor(env, fileDescriptor);
68    if (fd >= 0) {
69        jniSetFileDescriptorOfFD(env, fileDescriptor, -1);
70        close(fd);
71    }
72}
73
74static jint android_os_MemoryFile_read(JNIEnv* env, jobject clazz,
75        jobject fileDescriptor, jint address, jbyteArray buffer, jint srcOffset, jint destOffset,
76        jint count, jboolean unpinned)
77{
78    int fd = jniGetFDFromFileDescriptor(env, fileDescriptor);
79    if (unpinned && ashmem_pin_region(fd, 0, 0) == ASHMEM_WAS_PURGED) {
80        ashmem_unpin_region(fd, 0, 0);
81        jniThrowException(env, "java/io/IOException", "ashmem region was purged");
82        return -1;
83    }
84
85    jbyte* bytes = env->GetByteArrayElements(buffer, 0);
86    memcpy(bytes + destOffset, (const char *)address + srcOffset, count);
87    env->ReleaseByteArrayElements(buffer, bytes, 0);
88
89    if (unpinned) {
90        ashmem_unpin_region(fd, 0, 0);
91    }
92    return count;
93}
94
95static jint android_os_MemoryFile_write(JNIEnv* env, jobject clazz,
96        jobject fileDescriptor, jint address, jbyteArray buffer, jint srcOffset, jint destOffset,
97        jint count, jboolean unpinned)
98{
99    int fd = jniGetFDFromFileDescriptor(env, fileDescriptor);
100    if (unpinned && ashmem_pin_region(fd, 0, 0) == ASHMEM_WAS_PURGED) {
101        ashmem_unpin_region(fd, 0, 0);
102        jniThrowException(env, "java/io/IOException", "ashmem region was purged");
103        return -1;
104    }
105
106    jbyte* bytes = env->GetByteArrayElements(buffer, 0);
107    memcpy((char *)address + destOffset, bytes + srcOffset, count);
108    env->ReleaseByteArrayElements(buffer, bytes, 0);
109
110    if (unpinned) {
111        ashmem_unpin_region(fd, 0, 0);
112    }
113    return count;
114}
115
116static void android_os_MemoryFile_pin(JNIEnv* env, jobject clazz, jobject fileDescriptor, jboolean pin)
117{
118    int fd = jniGetFDFromFileDescriptor(env, fileDescriptor);
119    int result = (pin ? ashmem_pin_region(fd, 0, 0) : ashmem_unpin_region(fd, 0, 0));
120    if (result < 0) {
121        jniThrowException(env, "java/io/IOException", NULL);
122    }
123}
124
125static const JNINativeMethod methods[] = {
126    {"native_open",  "(Ljava/lang/String;I)Ljava/io/FileDescriptor;", (void*)android_os_MemoryFile_open},
127    {"native_mmap",  "(Ljava/io/FileDescriptor;I)I", (void*)android_os_MemoryFile_mmap},
128    {"native_munmap", "(II)V", (void*)android_os_MemoryFile_munmap},
129    {"native_close", "(Ljava/io/FileDescriptor;)V", (void*)android_os_MemoryFile_close},
130    {"native_read",  "(Ljava/io/FileDescriptor;I[BIIIZ)I", (void*)android_os_MemoryFile_read},
131    {"native_write", "(Ljava/io/FileDescriptor;I[BIIIZ)V", (void*)android_os_MemoryFile_write},
132    {"native_pin",   "(Ljava/io/FileDescriptor;Z)V", (void*)android_os_MemoryFile_pin},
133};
134
135static const char* const kClassPathName = "android/os/MemoryFile";
136
137int register_android_os_MemoryFile(JNIEnv* env)
138{
139    jclass clazz;
140
141    clazz = env->FindClass(kClassPathName);
142    LOG_FATAL_IF(clazz == NULL, "Unable to find class android.os.FileUtils");
143
144    return AndroidRuntime::registerNativeMethods(
145        env, kClassPathName,
146        methods, NELEM(methods));
147}
148
149}
150