1 /*
2 * Copyright (C) 2007 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 /*
18 * JNI helper functions.
19 *
20 * This file may be included by C or C++ code, which is trouble because jni.h
21 * uses different typedefs for JNIEnv in each language.
22 */
23 #pragma once
24
25 #include <sys/cdefs.h>
26
27 #include <jni.h>
28
29 #include <nativehelper/JNIHelp.h>
30
31 __BEGIN_DECLS
32
33 /*
34 * Gets the managed heap array backing a java.nio.Buffer instance.
35 *
36 * Returns nullptr if there is no array backing.
37 *
38 * This method performs a JNI call to java.nio.NIOAccess.getBaseArray().
39 */
40 jarray jniGetNioBufferBaseArray(C_JNIEnv* env, jobject nioBuffer);
41
42 /*
43 * Gets the offset of the current buffer position in bytes from the start of the managed heap
44 * array backing the buffer.
45 *
46 * Returns 0 if there is no array backing.
47 *
48 * This method performs a JNI call to java.nio.NIOAccess.getBaseArrayOffset().
49 */
50 jint jniGetNioBufferBaseArrayOffset(C_JNIEnv* env, jobject nioBuffer);
51
52 /*
53 * Gets field information from a java.nio.Buffer instance.
54 *
55 * Reads the |position|, |limit|, and |elementSizeShift| fields from the buffer instance.
56 *
57 * Returns the |address| field of the java.nio.Buffer instance which is only valid (non-zero) when
58 * the buffer is backed by a direct buffer.
59 */
60 jlong jniGetNioBufferFields(C_JNIEnv* env,
61 jobject nioBuffer,
62 /*out*/jint* position,
63 /*out*/jint* limit,
64 /*out*/jint* elementSizeShift);
65
66 /*
67 * Gets the current position from a java.nio.Buffer as a pointer to memory in a fixed buffer.
68 *
69 * Returns 0 if |nioBuffer| is not backed by a direct buffer.
70 *
71 * This method reads the |address|, |position|, and |elementSizeShift| fields from the
72 * java.nio.Buffer instance to calculate the pointer address for the current position.
73 */
74 jlong jniGetNioBufferPointer(C_JNIEnv* env, jobject nioBuffer);
75
76 /*
77 * Clear the cache of constants libnativehelper is using.
78 */
79 void jniUninitializeConstants();
80
81 __END_DECLS
82
83 /*
84 * For C++ code, we provide inlines that map to the C functions. g++ always
85 * inlines these, even on non-optimized builds.
86 */
87
88 #if defined(__cplusplus)
89
90 #include <android/file_descriptor_jni.h>
91
jniCreateFileDescriptor(JNIEnv * env,int fd)92 inline jobject jniCreateFileDescriptor(JNIEnv* env, int fd) {
93 jobject fileDescriptor = AFileDescriptor_create(env);
94 if (fileDescriptor != nullptr) {
95 AFileDescriptor_setFd(env, fileDescriptor, fd);
96 }
97 return fileDescriptor;
98 }
99
jniGetFDFromFileDescriptor(JNIEnv * env,jobject fileDescriptor)100 inline int jniGetFDFromFileDescriptor(JNIEnv* env, jobject fileDescriptor) {
101 if (fileDescriptor == nullptr) {
102 return -1;
103 }
104 return AFileDescriptor_getFd(env, fileDescriptor);
105 }
106
jniSetFileDescriptorOfFD(JNIEnv * env,jobject fileDescriptor,int value)107 inline void jniSetFileDescriptorOfFD(JNIEnv* env, jobject fileDescriptor, int value) {
108 if (fileDescriptor == nullptr) {
109 jniThrowNullPointerException(env, "fileDescriptor is null");
110 return;
111 }
112 AFileDescriptor_setFd(env, fileDescriptor, value);
113 }
114
jniGetNioBufferBaseArray(JNIEnv * env,jobject nioBuffer)115 inline jarray jniGetNioBufferBaseArray(JNIEnv* env, jobject nioBuffer) {
116 return jniGetNioBufferBaseArray(&env->functions, nioBuffer);
117 }
118
jniGetNioBufferBaseArrayOffset(JNIEnv * env,jobject nioBuffer)119 inline jint jniGetNioBufferBaseArrayOffset(JNIEnv* env, jobject nioBuffer) {
120 return jniGetNioBufferBaseArrayOffset(&env->functions, nioBuffer);
121 }
122
jniGetNioBufferFields(JNIEnv * env,jobject nioBuffer,jint * position,jint * limit,jint * elementSizeShift)123 inline jlong jniGetNioBufferFields(JNIEnv* env, jobject nioBuffer,
124 jint* position, jint* limit, jint* elementSizeShift) {
125 return jniGetNioBufferFields(&env->functions, nioBuffer,
126 position, limit, elementSizeShift);
127 }
128
jniGetNioBufferPointer(JNIEnv * env,jobject nioBuffer)129 inline jlong jniGetNioBufferPointer(JNIEnv* env, jobject nioBuffer) {
130 return jniGetNioBufferPointer(&env->functions, nioBuffer);
131 }
132
133 #endif // defined(__cplusplus)
134