1 /*
 2  * Copyright (c) 2018, 2019, Oracle and/or its affiliates. All rights reserved.
 3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 4  *
 5  * This code is free software; you can redistribute it and/or modify it
 6  * under the terms of the GNU General Public License version 2 only, as
 7  * published by the Free Software Foundation.
 8  *
 9  * This code is distributed in the hope that it will be useful, but WITHOUT
10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12  * version 2 for more details (a copy is included in the LICENSE file that
13  * accompanied this code).
14  *
15  * You should have received a copy of the GNU General Public License version
16  * 2 along with this work; if not, write to the Free Software Foundation,
17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18  *
19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20  * or visit www.oracle.com if you need additional information or have any
21  * questions.
22  *
23  */
24 
25 #ifndef SHARE_RUNTIME_JNIHANDLES_INLINE_HPP
26 #define SHARE_RUNTIME_JNIHANDLES_INLINE_HPP
27 
28 #include "runtime/jniHandles.hpp"
29 
30 #include "oops/access.inline.hpp"
31 #include "oops/oop.hpp"
32 #include "utilities/debug.hpp"
33 #include "utilities/globalDefinitions.hpp"
34 
35 inline bool JNIHandles::is_jweak(jobject handle) {
36   STATIC_ASSERT(weak_tag_size == 1);
37   STATIC_ASSERT(weak_tag_value == 1);
38   return (reinterpret_cast<uintptr_t>(handle) & weak_tag_mask) != 0;
39 }
40 
41 inline oop* JNIHandles::jobject_ptr(jobject handle) {
42   assert(!is_jweak(handle), "precondition");
43   return reinterpret_cast<oop*>(handle);
44 }
45 
46 inline oop* JNIHandles::jweak_ptr(jobject handle) {
47   assert(is_jweak(handle), "precondition");
48   char* ptr = reinterpret_cast<char*>(handle) - weak_tag_value;
49   return reinterpret_cast<oop*>(ptr);
50 }
51 
52 // external_guard is true if called from resolve_external_guard.
53 template <DecoratorSet decorators, bool external_guard>
54 inline oop JNIHandles::resolve_impl(jobject handle) {
55   assert(handle != NULL, "precondition");
56   assert(!current_thread_in_native(), "must not be in native");
57   oop result;
58   if (is_jweak(handle)) {       // Unlikely
59     result = NativeAccess<ON_PHANTOM_OOP_REF|decorators>::oop_load(jweak_ptr(handle));
60   } else {
61     result = NativeAccess<decorators>::oop_load(jobject_ptr(handle));
62     // Construction of jobjects canonicalize a null value into a null
63     // jobject, so for non-jweak the pointee should never be null.
64     assert(external_guard || result != NULL, "Invalid JNI handle");
65   }
66   return result;
67 }
68 
69 inline oop JNIHandles::resolve(jobject handle) {
70   oop result = NULL;
71   if (handle != NULL) {
72     result = resolve_impl<DECORATORS_NONE, false /* external_guard */>(handle);
73   }
74   return result;
75 }
76 
77 inline oop JNIHandles::resolve_no_keepalive(jobject handle) {
78   oop result = NULL;
79   if (handle != NULL) {
80     result = resolve_impl<AS_NO_KEEPALIVE, false /* external_guard */>(handle);
81   }
82   return result;
83 }
84 
85 inline oop JNIHandles::resolve_non_null(jobject handle) {
86   assert(handle != NULL, "JNI handle should not be null");
87   oop result = resolve_impl<DECORATORS_NONE, false /* external_guard */>(handle);
88   assert(result != NULL, "NULL read from jni handle");
89   return result;
90 }
91 
92 inline void JNIHandles::destroy_local(jobject handle) {
93   if (handle != NULL) {
94     assert(!is_jweak(handle), "Invalid JNI local handle");
95     NativeAccess<>::oop_store(jobject_ptr(handle), (oop)NULL);
96   }
97 }
98 
99 #endif // SHARE_RUNTIME_JNIHANDLES_INLINE_HPP