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 SCOPEDUTFCHARS_H_ 18 #define SCOPEDUTFCHARS_H_ 19 20 #include <conscrypt/jniutil.h> 21 #include <string.h> 22 23 // A smart pointer that provides read-only access to a Java string's UTF chars. 24 // Unlike GetStringUTFChars, we throw NullPointerException rather than abort if 25 // passed a null jstring, and c_str will return nullptr. 26 // This makes the correct idiom very simple: 27 // 28 // ScopedUtfChars name(env, java_name); 29 // if (name.c_str() == nullptr) { 30 // return nullptr; 31 // } 32 class ScopedUtfChars { 33 public: ScopedUtfChars(JNIEnv * env,jstring s)34 ScopedUtfChars(JNIEnv* env, jstring s) : env_(env), string_(s) { 35 if (s == nullptr) { 36 utf_chars_ = nullptr; 37 conscrypt::jniutil::throwNullPointerException(env, nullptr); 38 } else { 39 utf_chars_ = env->GetStringUTFChars(s, nullptr); 40 } 41 } 42 ~ScopedUtfChars()43 ~ScopedUtfChars() { 44 if (utf_chars_) { 45 env_->ReleaseStringUTFChars(string_, utf_chars_); 46 } 47 } 48 c_str()49 const char* c_str() const { 50 return utf_chars_; 51 } 52 size()53 size_t size() const { 54 return strlen(utf_chars_); 55 } 56 57 const char& operator[](size_t n) const { 58 return utf_chars_[n]; 59 } 60 61 private: 62 JNIEnv* env_; 63 jstring string_; 64 const char* utf_chars_; 65 66 // Disallow copy and assignment. 67 ScopedUtfChars(const ScopedUtfChars&); 68 void operator=(const ScopedUtfChars&); 69 }; 70 71 #endif // SCOPEDUTFCHARS_H_ 72