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 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 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 65 int register_android_os_MemoryFile(JNIEnv* env) { 66 return RegisterMethodsOrDie(env, "android/os/MemoryFile", methods, NELEM(methods)); 67 } 68 69 } 70
