1/*
2 * Copyright (C) 2006 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 "JNIHelp"
18
19#include "JNIHelp.h"
20
21#include "log_compat.h"
22
23#include <stdio.h>
24#include <stdlib.h>
25#include <string.h>
26#include <assert.h>
27
28/**
29 * Equivalent to ScopedLocalRef, but for C_JNIEnv instead. (And slightly more powerful.)
30 */
31template<typename T>
32class scoped_local_ref {
33public:
34    scoped_local_ref(JNIEnv* env, T localRef = NULL)
35    : mEnv(env), mLocalRef(localRef)
36    {
37    }
38
39    ~scoped_local_ref() {
40        reset();
41    }
42
43    void reset(T localRef = NULL) {
44        if (mLocalRef != NULL) {
45            mEnv->DeleteLocalRef(mLocalRef);
46            mLocalRef = localRef;
47        }
48    }
49
50    T get() const {
51        return mLocalRef;
52    }
53
54private:
55    JNIEnv* mEnv;
56    T mLocalRef;
57
58    // Disallow copy and assignment.
59    scoped_local_ref(const scoped_local_ref&);
60    void operator=(const scoped_local_ref&);
61};
62
63static jclass findClass(JNIEnv* env, const char* className) {
64    return env->FindClass(className);
65}
66
67extern "C" int jniRegisterNativeMethods(JNIEnv* env, const char* className,
68    const JNINativeMethod* gMethods, int numMethods)
69{
70    ALOGV("Registering %s's %d native methods...", className, numMethods);
71
72    scoped_local_ref<jclass> c(env, findClass(env, className));
73    if (c.get() == NULL) {
74        char* msg;
75        (void)asprintf(&msg, "Native registration unable to find class '%s'; aborting...",
76                       className);
77        env->FatalError(msg);
78    }
79
80    if (env->RegisterNatives(c.get(), gMethods, numMethods) < 0) {
81        char* msg;
82        (void)asprintf(&msg, "RegisterNatives failed for '%s'; aborting...", className);
83        env->FatalError(msg);
84    }
85
86    return 0;
87}
88
89#ifdef __cplusplus
90extern "C"
91#endif
92int jniThrowException(JNIEnv* env, const char* className, const char* msg) {
93    jclass exceptionClass = env->FindClass(className);
94
95    if (exceptionClass == NULL) {
96        ALOGD("Unable to find exception class %s", className);
97        /* ClassNotFoundException now pending */
98        return -1;
99    }
100
101    if (env->ThrowNew(exceptionClass, msg) != JNI_OK) {
102        ALOGD("Failed throwing '%s' '%s'", className, msg);
103        /* an exception, most likely OOM, will now be pending */
104        return -1;
105    }
106
107    env->DeleteLocalRef(exceptionClass);
108    return 0;
109}
110
111int jniThrowExceptionFmt(JNIEnv* env, const char* className, const char* fmt, va_list args) {
112    char msgBuf[512];
113    vsnprintf(msgBuf, sizeof(msgBuf), fmt, args);
114    return jniThrowException(env, className, msgBuf);
115}
116
117int jniThrowNullPointerException(JNIEnv* env, const char* msg) {
118    return jniThrowException(env, "java/lang/NullPointerException", msg);
119}
120
121int jniThrowRuntimeException(JNIEnv* env, const char* msg) {
122    return jniThrowException(env, "java/lang/RuntimeException", msg);
123}
124
125int jniThrowIOException(JNIEnv* env, int errnum) {
126    char buffer[80];
127    const char* message = jniStrError(errnum, buffer, sizeof(buffer));
128    return jniThrowException(env, "java/io/IOException", message);
129}
130
131const char* jniStrError(int errnum, char* buf, size_t buflen) {
132#if __GLIBC__
133    // Note: glibc has a nonstandard strerror_r that returns char* rather than POSIX's int.
134    // char *strerror_r(int errnum, char *buf, size_t n);
135    return strerror_r(errnum, buf, buflen);
136#else
137    int rc = strerror_r(errnum, buf, buflen);
138    if (rc != 0) {
139        // (POSIX only guarantees a value other than 0. The safest
140        // way to implement this function is to use C++ and overload on the
141        // type of strerror_r to accurately distinguish GNU from POSIX.)
142        snprintf(buf, buflen, "errno %d", errnum);
143    }
144    return buf;
145#endif
146}
147
148int jniGetFDFromFileDescriptor(JNIEnv* env, jobject fileDescriptor) {
149    scoped_local_ref<jclass> localClass(env, env->FindClass("java/io/FileDescriptor"));
150    static jfieldID fid = env->GetFieldID(localClass.get(), "descriptor", "I");
151    if (fileDescriptor != NULL) {
152        return env->GetIntField(fileDescriptor, fid);
153    } else {
154        return -1;
155    }
156}
157