Andreas Gampe | d299c07 | 2017-10-17 10:50:00 -0700 | [diff] [blame] | 1 | /* |
| 2 | * Copyright (C) 2010 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 | #ifndef SCOPED_UTF_CHARS_H_ |
| 18 | #define SCOPED_UTF_CHARS_H_ |
| 19 | |
| 20 | #include <string.h> |
| 21 | |
| 22 | #include "jni.h" |
| 23 | #include "nativehelper_utils.h" |
| 24 | |
| 25 | // A smart pointer that provides read-only access to a Java string's UTF chars. |
| 26 | // Unlike GetStringUTFChars, we throw NullPointerException rather than abort if |
| 27 | // passed a null jstring, and c_str will return nullptr. |
| 28 | // This makes the correct idiom very simple: |
| 29 | // |
| 30 | // ScopedUtfChars name(env, java_name); |
| 31 | // if (name.c_str() == nullptr) { |
| 32 | // return nullptr; |
| 33 | // } |
| 34 | class ScopedUtfChars { |
| 35 | public: |
| 36 | ScopedUtfChars(JNIEnv* env, jstring s) : env_(env), string_(s) { |
| 37 | if (s == nullptr) { |
| 38 | utf_chars_ = nullptr; |
| 39 | jniThrowNullPointerException(env, nullptr); |
| 40 | } else { |
| 41 | utf_chars_ = env->GetStringUTFChars(s, nullptr); |
| 42 | } |
| 43 | } |
| 44 | |
| 45 | ScopedUtfChars(ScopedUtfChars&& rhs) : |
| 46 | env_(rhs.env_), string_(rhs.string_), utf_chars_(rhs.utf_chars_) { |
| 47 | rhs.env_ = nullptr; |
| 48 | rhs.string_ = nullptr; |
| 49 | rhs.utf_chars_ = nullptr; |
| 50 | } |
| 51 | |
| 52 | ~ScopedUtfChars() { |
| 53 | if (utf_chars_) { |
| 54 | env_->ReleaseStringUTFChars(string_, utf_chars_); |
| 55 | } |
| 56 | } |
| 57 | |
| 58 | ScopedUtfChars& operator=(ScopedUtfChars&& rhs) { |
| 59 | if (this != &rhs) { |
| 60 | // Delete the currently owned UTF chars. |
| 61 | this->~ScopedUtfChars(); |
| 62 | |
| 63 | // Move the rhs ScopedUtfChars and zero it out. |
| 64 | env_ = rhs.env_; |
| 65 | string_ = rhs.string_; |
| 66 | utf_chars_ = rhs.utf_chars_; |
| 67 | rhs.env_ = nullptr; |
| 68 | rhs.string_ = nullptr; |
| 69 | rhs.utf_chars_ = nullptr; |
| 70 | } |
| 71 | return *this; |
| 72 | } |
| 73 | |
| 74 | const char* c_str() const { |
| 75 | return utf_chars_; |
| 76 | } |
| 77 | |
| 78 | size_t size() const { |
| 79 | return strlen(utf_chars_); |
| 80 | } |
| 81 | |
| 82 | const char& operator[](size_t n) const { |
| 83 | return utf_chars_[n]; |
| 84 | } |
| 85 | |
| 86 | private: |
| 87 | JNIEnv* env_; |
| 88 | jstring string_; |
| 89 | const char* utf_chars_; |
| 90 | |
| 91 | DISALLOW_COPY_AND_ASSIGN(ScopedUtfChars); |
| 92 | }; |
| 93 | |
| 94 | #endif // SCOPED_UTF_CHARS_H_ |