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  * TODO: remove C support.
24  */
25 #ifndef NATIVEHELPER_JNIHELP_H_
26 #define NATIVEHELPER_JNIHELP_H_
27 
28 #include "jni.h"
29 #include <errno.h>
30 #include <unistd.h>
31 
32 #ifndef NELEM
33 # define NELEM(x) ((int) (sizeof(x) / sizeof((x)[0])))
34 #endif
35 
36 #ifdef __cplusplus
37 extern "C" {
38 #endif
39 
40 /*
41  * Register one or more native methods with a particular class.
42  * "className" looks like "java/lang/String". Aborts on failure.
43  * TODO: fix all callers and change the return type to void.
44  */
45 int jniRegisterNativeMethods(C_JNIEnv* env, const char* className, const JNINativeMethod* gMethods, int numMethods);
46 
47 /*
48  * Throw an exception with the specified class and an optional message.
49  *
50  * The "className" argument will be passed directly to FindClass, which
51  * takes strings with slashes (e.g. "java/lang/Object").
52  *
53  * If an exception is currently pending, we log a warning message and
54  * clear it.
55  *
56  * Returns 0 on success, nonzero if something failed (e.g. the exception
57  * class couldn't be found, so *an* exception will still be pending).
58  *
59  * Currently aborts the VM if it can't throw the exception.
60  */
61 int jniThrowException(C_JNIEnv* env, const char* className, const char* msg);
62 
63 /*
64  * Throw a java.lang.NullPointerException, with an optional message.
65  */
66 int jniThrowNullPointerException(C_JNIEnv* env, const char* msg);
67 
68 /*
69  * Throw a java.lang.RuntimeException, with an optional message.
70  */
71 int jniThrowRuntimeException(C_JNIEnv* env, const char* msg);
72 
73 /*
74  * Throw a java.io.IOException, generating the message from errno.
75  */
76 int jniThrowIOException(C_JNIEnv* env, int errnum);
77 
78 /*
79  * Return a pointer to a locale-dependent error string explaining errno
80  * value 'errnum'. The returned pointer may or may not be equal to 'buf'.
81  * This function is thread-safe (unlike strerror) and portable (unlike
82  * strerror_r).
83  */
84 const char* jniStrError(int errnum, char* buf, size_t buflen);
85 
86 /*
87  * Returns a new java.io.FileDescriptor for the given int fd.
88  */
89 jobject jniCreateFileDescriptor(C_JNIEnv* env, int fd);
90 
91 /*
92  * Returns the int fd from a java.io.FileDescriptor.
93  */
94 int jniGetFDFromFileDescriptor(C_JNIEnv* env, jobject fileDescriptor);
95 
96 /*
97  * Sets the int fd in a java.io.FileDescriptor.
98  */
99 void jniSetFileDescriptorOfFD(C_JNIEnv* env, jobject fileDescriptor, int value);
100 
101 /*
102  * Returns the reference from a java.lang.ref.Reference.
103  */
104 jobject jniGetReferent(C_JNIEnv* env, jobject ref);
105 
106 /*
107  * Log a message and an exception.
108  * If exception is NULL, logs the current exception in the JNI environment.
109  */
110 void jniLogException(C_JNIEnv* env, int priority, const char* tag, jthrowable exception);
111 
112 #ifdef __cplusplus
113 }
114 #endif
115 
116 
117 /*
118  * For C++ code, we provide inlines that map to the C functions.  g++ always
119  * inlines these, even on non-optimized builds.
120  */
121 #if defined(__cplusplus)
jniRegisterNativeMethods(JNIEnv * env,const char * className,const JNINativeMethod * gMethods,int numMethods)122 inline int jniRegisterNativeMethods(JNIEnv* env, const char* className, const JNINativeMethod* gMethods, int numMethods) {
123     return jniRegisterNativeMethods(&env->functions, className, gMethods, numMethods);
124 }
125 
jniThrowException(JNIEnv * env,const char * className,const char * msg)126 inline int jniThrowException(JNIEnv* env, const char* className, const char* msg) {
127     return jniThrowException(&env->functions, className, msg);
128 }
129 
130 extern "C" int jniThrowExceptionFmt(C_JNIEnv* env, const char* className, const char* fmt, va_list args);
131 
132 /*
133  * Equivalent to jniThrowException but with a printf-like format string and
134  * variable-length argument list. This is only available in C++.
135  */
jniThrowExceptionFmt(JNIEnv * env,const char * className,const char * fmt,...)136 inline int jniThrowExceptionFmt(JNIEnv* env, const char* className, const char* fmt, ...) {
137     va_list args;
138     va_start(args, fmt);
139     return jniThrowExceptionFmt(&env->functions, className, fmt, args);
140     va_end(args);
141 }
142 
jniThrowNullPointerException(JNIEnv * env,const char * msg)143 inline int jniThrowNullPointerException(JNIEnv* env, const char* msg) {
144     return jniThrowNullPointerException(&env->functions, msg);
145 }
146 
jniThrowRuntimeException(JNIEnv * env,const char * msg)147 inline int jniThrowRuntimeException(JNIEnv* env, const char* msg) {
148     return jniThrowRuntimeException(&env->functions, msg);
149 }
150 
jniThrowIOException(JNIEnv * env,int errnum)151 inline int jniThrowIOException(JNIEnv* env, int errnum) {
152     return jniThrowIOException(&env->functions, errnum);
153 }
154 
jniCreateFileDescriptor(JNIEnv * env,int fd)155 inline jobject jniCreateFileDescriptor(JNIEnv* env, int fd) {
156     return jniCreateFileDescriptor(&env->functions, fd);
157 }
158 
jniGetFDFromFileDescriptor(JNIEnv * env,jobject fileDescriptor)159 inline int jniGetFDFromFileDescriptor(JNIEnv* env, jobject fileDescriptor) {
160     return jniGetFDFromFileDescriptor(&env->functions, fileDescriptor);
161 }
162 
jniSetFileDescriptorOfFD(JNIEnv * env,jobject fileDescriptor,int value)163 inline void jniSetFileDescriptorOfFD(JNIEnv* env, jobject fileDescriptor, int value) {
164     jniSetFileDescriptorOfFD(&env->functions, fileDescriptor, value);
165 }
166 
jniGetReferent(JNIEnv * env,jobject ref)167 inline jobject jniGetReferent(JNIEnv* env, jobject ref) {
168     return jniGetReferent(&env->functions, ref);
169 }
170 
171 inline void jniLogException(JNIEnv* env, int priority, const char* tag, jthrowable exception = NULL) {
172     jniLogException(&env->functions, priority, tag, exception);
173 }
174 
175 #endif
176 
177 /*
178  * TEMP_FAILURE_RETRY is defined by some, but not all, versions of
179  * <unistd.h>. (Alas, it is not as standard as we'd hoped!) So, if it's
180  * not already defined, then define it here.
181  */
182 #ifndef TEMP_FAILURE_RETRY
183 /* Used to retry syscalls that can return EINTR. */
184 #define TEMP_FAILURE_RETRY(exp) ({         \
185     typeof (exp) _rc;                      \
186     do {                                   \
187         _rc = (exp);                       \
188     } while (_rc == -1 && errno == EINTR); \
189     _rc; })
190 #endif
191 
192 #endif  /* NATIVEHELPER_JNIHELP_H_ */
193