Index: base/android/jni_int_wrapper.h |
diff --git a/base/android/jni_int_wrapper.h b/base/android/jni_int_wrapper.h |
new file mode 100644 |
index 0000000000000000000000000000000000000000..6df4e0617847025967de3de7123ae38a37741a7d |
--- /dev/null |
+++ b/base/android/jni_int_wrapper.h |
@@ -0,0 +1,38 @@ |
+// 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_ |
+ |
+#include <stdint.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. |
bulach
2014/05/02 16:55:56
I think we could do with a
#ifdef NDEBUG
// Don'
|
+ |
+class jni_int_wrapper { |
bulach
2014/05/02 16:55:56
nit: should be JniIntWrapper
|
+ public: |
+ jni_int_wrapper() : i_(0) {} |
+ jni_int_wrapper(int i) : i_(i) {} |
+ jni_int_wrapper(const jni_int_wrapper& ji) : i_(ji.i_) {} |
+ template <class T> jni_int_wrapper(const T& t) : i_(t) {} |
+ jint asJint() const { return i_; } |
bulach
2014/05/02 16:55:56
nit: and here, as_jint()
|
+ 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. |
+ jni_int_wrapper(long); |
+ jint i_; |
+}; |
+ |
+#endif // BASE_ANDROID_JNI_INT_WRAPPER_H_ |