Index: base/android/jni_int_wrapper.h |
diff --git a/base/android/jni_int_wrapper.h b/base/android/jni_int_wrapper.h |
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+// Copyright (c) 2014 The Chromium Authors. All rights reserved. |
+// Use of this source code is governed by a BSD-style license that can be |
+// found in the LICENSE file. |
+ |
+#ifndef BASE_ANDROID_JNI_INT_WRAPPER_H_ |
+#define BASE_ANDROID_JNI_INT_WRAPPER_H_ |
+ |
+// Wrapper used to receive int when calling Java from native. |
+// The wrapper disallows automatic conversion of long to int. |
+// This is to avoid a common anti-pattern where a Java int is used |
+// to receive a native pointer. Please use a Java long to receive |
+// native pointers, so that the code works on both 32-bit and 64-bit |
+// platforms. Note the wrapper allows other lossy conversions into |
+// jint that could be consider anti-patterns, such as from size_t. |
+ |
+// Checking is only done in debugging builds. |
+ |
+#ifdef NDEBUG |
+ |
+typedef jint JniIntWrapper; |
+ |
+// This inline is sufficiently trivial that it does not change the |
+// final code generated by g++. |
+inline jint as_jint(JniIntWrapper wrapper) { |
+ return wrapper; |
+} |
+ |
+#else |
+ |
+class JniIntWrapper { |
+ public: |
+ JniIntWrapper() : i_(0) {} |
+ JniIntWrapper(int i) : i_(i) {} |
+ JniIntWrapper(const JniIntWrapper& ji) : i_(ji.i_) {} |
+ template <class T> JniIntWrapper(const T& t) : i_(t) {} |
+ jint as_jint() const { return i_; } |
+ private: |
+ // If you get an "is private" error at the line below it is because you used |
+ // an implicit conversion to convert a long to an int when calling Java. |
+ // We disallow this, as a common anti-pattern allows converting a native |
+ // pointer (intptr_t) to a Java int. Please use a Java long to represent |
+ // a native pointer. If you want a lossy conversion, please use an |
+ // explicit conversion in your C++ code. Note an error is only seen when |
+ // compiling on a 64-bit platform, as intptr_t is indistinguishable from |
+ // int on 32-bit platforms. |
+ JniIntWrapper(long); |
+ jint i_; |
+}; |
+ |
+inline jint as_jint(const JniIntWrapper& wrapper) { |
+ return wrapper.as_jint(); |
+} |
+ |
+#endif // NDEBUG |
+ |
+#endif // BASE_ANDROID_JNI_INT_WRAPPER_H_ |