/*
* Copyright (C) 2017 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* Compile-time, zero-cost checking of JNI signatures against their C++ function type.
* This can trigger compile-time assertions if any of the input is invalid:
* (a) The signature specified does not conform to the JNI function descriptor syntax.
* (b) The C++ function is itself an invalid JNI function (e.g. missing JNIEnv*, etc).
* (c) The descriptor does not match the C++ function (e.g. "()V" will not match jint(jint)).
*
* The fundamental macros are as following:
* MAKE_JNI_[FAST_|CRITICAL_]NATIVE_METHOD - Create a checked JNINativeMethod{name, sig, func}.
* MAKE_JNI_[FAST_|CRITICAL_]NATIVE_METHOD_AUTOSIG - Same as above, but infer the JNI signature.
*
* Usage examples:
* // path/to/package/KlassName.java
* class KlassName {
* native jobject normal(int x);
* @FastNative native jobject fast(int x);
* @CriticalNative native int critical(long ptr);
* }
* // path_to_package_KlassName.cpp
* jobject KlassName_normal(JNIEnv*,jobject,jint) {...}
* jobject KlassName_fast(JNIEnv*,jobject,jint) {...}
* jint KlassName_critical(jlong) {...}
*
* // Manually specify each signature:
* JNINativeMethod[] gMethods = {
* MAKE_JNI_NATIVE_METHOD("normal", "(I)Ljava/lang/Object;", KlassName_normal),
* MAKE_JNI_FAST_NATIVE_METHOD("fast", "(I)Ljava/lang/Object;", KlassName_fast),
* MAKE_JNI_CRITICAL_NATIVE_METHOD("critical", "(Z)I", KlassName_critical),
* };
*
* // Automatically infer the signature:
* JNINativeMethod[] gMethodsAutomaticSignature = {
* MAKE_JNI_NATIVE_METHOD_AUTOSIG("normal", KlassName_normal),
* MAKE_JNI_FAST_NATIVE_METHOD_AUTOSIG("fast", KlassName_fast),
* MAKE_JNI_CRITICAL_NATIVE_METHOD_AUTOSIG("critical", KlassName_critical),
* };
*
* // and then call JNIEnv::RegisterNatives with gMethods as usual.
*
* For convenience the following macros are defined:
* [FAST_|CRITICAL_]NATIVE_METHOD - Return JNINativeMethod for class, func name, and signature.
* OVERLOADED_[FAST_|CRITICAL_]NATIVE_METHOD - Same as above but allows a separate func identifier.
* [FAST_|CRITICAL_]NATIVE_METHOD_AUTOSIG - Return JNINativeMethod, sig inferred from function.
*
* The FAST_ prefix corresponds to functions annotated with @FastNative,
* and the CRITICAL_ prefix corresponds to functions annotated with @CriticalNative.
* See dalvik.annotation.optimization.CriticalNative for more details.
*
* =======================================
* Checking rules
* =======================================
*
* ---------------------------------------
* JNI descriptor syntax for functions
*
* Refer to "Chapter 3: JNI Types and Data Structures" of the JNI specification
* under the subsection "Type Signatures" table entry "method type".
*
* JNI signatures not conforming to the above syntax are rejected.
* ---------------------------------------
* C++ function types
*
* A normal or @FastNative JNI function type must be of the form
*
* ReturnType (JNIEnv*, jclass|jobject, [ArgTypes...]) {}
*
* A @CriticalNative JNI function type:
*
* must be of the form... ReturnType ([ArgTypes...]){}
* and must not contain any Reference Types.
*
* Refer to "Chapter 3: JNI Types and Data Structures" of the JNI specification
* under the subsection "Primitive Types" and "Reference Types" for the list
* of valid argument/return types.
*
* C++ function types not conforming to the above requirements are rejected.
* ---------------------------------------
* Matching of C++ function type against JNI function descriptor.
*
* Assuming all of the above conditions are met for signature and C++ type validity,
* then matching between the signature and the type validity can occur:
*
* Given a signature (Args...)Ret and the
* C++ function type of the form "CRet fn(JNIEnv*, jclass|jobject, CArgs...)",
* or for @CriticalNative of the form "CRet fn(CArgs...)"
*
* The number of Args... and the number of CArgs... must be equal.
*
* If so, attempt to match every component from the signature and function type
* against each other:
*
* ReturnType:
* V <-> void
* ArgumentType
*
* ArgumentType:
* PrimitiveType
* ReferenceType [except for @CriticalNative]
*
* PrimitiveType:
* Z <-> jboolean
* B <-> jbyte
* C <-> jchar
* S <-> jshort
* I <-> jint
* J <-> jlong
* F <-> jfloat
* D <-> jdouble
*
* ReferenceType:
* Ljava/lang/String; <-> jstring
* Ljava/lang/Class; <-> jclass
* L*; <- jobject
* Ljava/lang/Throwable; -> jthrowable
* L*; <- jthrowable
* [ PrimitiveType <-> ${CPrimitiveType}Array
* [ ReferenceType <-> jobjectArray
* [* <- jarray
*
* Wherein <-> represents a strong match (if the left or right pattern occurs,
* then left must match right, otherwise matching fails). <- and -> represent
* weak matches (that is, other match rules can be still attempted).
*
* Sidenote: Whilst a jobject could also represent a jclass, jstring, etc,
* the stricter approach is taken: the most exact C++ type must be used.
*/
#ifndef NATIVEHELPER_JNI_MACROS_H
#define NATIVEHELPER_JNI_MACROS_H
// The below basic macros do not perform automatic stringification,
// invoked e.g. as MAKE_JNI_NATIVE_METHOD("some_name", "()V", void_fn)
// An expression that evaluates to JNINativeMethod { name, signature, function },
// and applies the above compile-time checking for signature+function.
// The equivalent Java Language code must not be annotated with @FastNative/@CriticalNative.
#define MAKE_JNI_NATIVE_METHOD(name, signature, function) \
_NATIVEHELPER_JNI_MAKE_METHOD(kNormalNative, name, signature, function)
// An expression that evaluates to JNINativeMethod { name, signature, function },
// and applies the above compile-time checking for signature+function.
// The equivalent Java Language code must be annotated with @FastNative.
#define MAKE_JNI_FAST_NATIVE_METHOD(name, signature, function) \
_NATIVEHELPER_JNI_MAKE_METHOD(kFastNative, name, signature, function)
// An expression that evaluates to JNINativeMethod { name, signature, function },
// and applies the above compile-time checking for signature+function.
// The equivalent Java Language code must be annotated with @CriticalNative.
#define MAKE_JNI_CRITICAL_NATIVE_METHOD(name, signature, function) \
_NATIVEHELPER_JNI_MAKE_METHOD(kCriticalNative, name, signature, function)
// Automatically signature-inferencing macros are also available,
// which also checks the C++ function types for validity:
// An expression that evalutes to JNINativeMethod { name, infersig(function), function) }
// by inferring the signature at compile-time. Only works when the C++ function type
// corresponds to one unambigous JNI parameter (e.g. 'jintArray' -> '[I' but 'jobject' -> ???).
//
// The equivalent Java Language code must not be annotated with @FastNative/@CriticalNative.
#define MAKE_JNI_NATIVE_METHOD_AUTOSIG(name, function) \
_NATIVEHELPER_JNI_MAKE_METHOD_AUTOSIG(kNormalNative, name, function)
// An expression that evalutes to JNINativeMethod { name, infersig(function), function) }
// by inferring the signature at compile-time. Only works when the C++ function type
// corresponds to one unambigous JNI parameter (e.g. 'jintArray' -> '[I' but 'jobject' -> ???).
//
// The equivalent Java Language code must be annotated with @FastNative.
#define MAKE_JNI_FAST_NATIVE_METHOD_AUTOSIG(name, function) \
_NATIVEHELPER_JNI_MAKE_METHOD_AUTOSIG(kFastNative, name, function)
// An expression that evalutes to JNINativeMethod { name, infersig(function), function) }
// by inferring the signature at compile-time.
//
// The equivalent Java Language code must be annotated with @CriticalNative.
#define MAKE_JNI_CRITICAL_NATIVE_METHOD_AUTOSIG(name, function) \
_NATIVEHELPER_JNI_MAKE_METHOD_AUTOSIG(kCriticalNative, name, function)
// Convenience macros when the functions follow the naming convention:
// .java file .cpp file
// JavaLanguageName <-> ${ClassName}_${JavaLanguageName}
//
// Stringification is done automatically, invoked as:
// NATIVE_[FAST_|CRITICAL]_METHOD(ClassName, JavaLanguageName, Signature)
//
// Intended to construct a JNINativeMethod.
// (Assumes the C name is the ClassName_JavaMethodName).
//
// The Java Language code must be annotated with one of (none,@FastNative,@CriticalNative)
// for the (none,FAST_,CRITICAL_) variants of these macros.
#define NATIVE_METHOD(className, functionName, signature) \
MAKE_JNI_NATIVE_METHOD(#functionName, signature, className ## _ ## functionName)
#define OVERLOADED_NATIVE_METHOD(className, functionName, signature, identifier) \
MAKE_JNI_NATIVE_METHOD(#functionName, signature, className ## _ ## identifier)
#define NATIVE_METHOD_AUTOSIG(className, functionName) \
MAKE_JNI_NATIVE_METHOD_AUTOSIG(#functionName, className ## _ ## functionName)
#define FAST_NATIVE_METHOD(className, functionName, signature) \
MAKE_JNI_FAST_NATIVE_METHOD(#functionName, signature, className ## _ ## functionName)
#define OVERLOADED_FAST_NATIVE_METHOD(className, functionName, signature, identifier) \
MAKE_JNI_FAST_NATIVE_METHOD(#functionName, signature, className ## _ ## identifier)
#define FAST_NATIVE_METHOD_AUTOSIG(className, functionName) \
MAKE_JNI_FAST_NATIVE_METHOD_AUTOSIG(#functionName, className ## _ ## functionName)
#define CRITICAL_NATIVE_METHOD(className, functionName, signature) \
MAKE_JNI_CRITICAL_NATIVE_METHOD(#functionName, signature, className ## _ ## functionName)
#define OVERLOADED_CRITICAL_NATIVE_METHOD(className, functionName, signature, identifier) \
MAKE_JNI_CRITICAL_NATIVE_METHOD(#functionName, signature, className ## _ ## identifier)
#define CRITICAL_NATIVE_METHOD_AUTOSIG(className, functionName) \
MAKE_JNI_CRITICAL_NATIVE_METHOD_AUTOSIG(#functionName, className ## _ ## functionName)
////////////////////////////////////////////////////////
// IMPLEMENTATION ONLY.
// DO NOT USE DIRECTLY.
////////////////////////////////////////////////////////
#if defined(__cplusplus) && __cplusplus >= 201402L
#include "nativehelper/detail/signature_checker.h" // for MAKE_CHECKED_JNI_NATIVE_METHOD
#endif
// Expands to an expression whose type is JNINativeMethod.
// This is for older versions of C++ or C, so it has no compile-time checking.
#define _NATIVEHELPER_JNI_MAKE_METHOD_OLD(kind, name, sig, fn) \
( \
(JNINativeMethod) { \
(name), \
(sig), \
_NATIVEHELPER_JNI_MACRO_CAST(reinterpret_cast, void *)(fn) \
} \
)
// C++14 or better, use compile-time checking.
#if defined(__cplusplus) && __cplusplus >= 201402L
// Expands to a compound expression whose type is JNINativeMethod.
#define _NATIVEHELPER_JNI_MAKE_METHOD(kind, name, sig, fn) \
MAKE_CHECKED_JNI_NATIVE_METHOD(kind, name, sig, fn)
// Expands to a compound expression whose type is JNINativeMethod.
#define _NATIVEHELPER_JNI_MAKE_METHOD_AUTOSIG(kind, name, function) \
MAKE_INFERRED_JNI_NATIVE_METHOD(kind, name, function)
#else
// Older versions of C++ or C code get the regular macro that's unchecked.
// Expands to a compound expression whose type is JNINativeMethod.
#define _NATIVEHELPER_JNI_MAKE_METHOD(kind, name, sig, fn) \
_NATIVEHELPER_JNI_MAKE_METHOD_OLD(kind, name, sig, fn)
// Need C++14 or newer to use the AUTOSIG macros.
#define _NATIVEHELPER_JNI_MAKE_METHOD_AUTOSIG(kind, name, function) \
static_assert(false, "Cannot infer JNI signatures prior to C++14 for function " #function);
#endif // C++14 check
// C-style cast for C, C++-style cast for C++ to avoid warnings/errors.
#if defined(__cplusplus)
#define _NATIVEHELPER_JNI_MACRO_CAST(which_cast, to) \
which_cast<to>
#else
#define _NATIVEHELPER_JNI_MACRO_CAST(which_cast, to) \
(to)
#endif
#endif // NATIVEHELPER_JNI_MACROS_H