1/*
2 * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2018, SAP SE. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26#include "precompiled.hpp"
27#include "classfile/systemDictionary.hpp"
28#include "memory/resourceArea.hpp"
29#include "oops/constantPool.hpp"
30#include "oops/reflectionAccessorImplKlassHelper.hpp"
31#include "utilities/constantTag.hpp"
32#include "utilities/debug.hpp"
33#include "utilities/globalDefinitions.hpp"
34
35// This code extracts name of target class, method and signature from the constant pool of a class
36// assumed to be of type jdk/internal/reflect/Generated{SerializationConstructor|Constructor|Method}AccessorXXX.
37// Since this may be affected by bitrot if these classes change, extra care is taken to make the
38// release build of this coding robust.
39
40// We extract target class name, method name and sig from the constant pool of the Accessor class.
41// This is an excerpt of the Constant pool (see jdk/internal/reflect/MethodAccessorGenerator.java:)
42
43// (^ = Only present if generating SerializationConstructorAccessor)
44// 1 [UTF-8] [This class's name]
45// 2 [CONSTANT_Class_info] for above
46// 3 [UTF-8] "jdk/internal/reflect/{MethodAccessorImpl,ConstructorAccessorImpl,SerializationConstructorAccessorImpl}"
47// 4 [CONSTANT_Class_info] for above
48// 5 [UTF-8] [Target class's name]
49// 6 [CONSTANT_Class_info] for above
50// 7^ [UTF-8] [Serialization: Class's name in which to invoke constructor]
51// 8^ [CONSTANT_Class_info] for above
52// 9 [UTF-8] target method or constructor name
53// 10 [UTF-8] target method or constructor signature
54
55// Note that these strings are found at slightly different slots depending on the class type:
56// - MethodAccessorImpl, ConstructoreAccessorImpl: slots 5, 7 and 8.
57// - SerializationConstructorAccessorImpl: slots 5, 9 and 10.
58// Unfortunately SerializationConstructorAccessorImpl is a child of ConstructoreAccessorImpl and there
59// is no easy way to tell them apart. So we examine parent class name.
60
61enum cpi_slots {
62 cpi_slot_parent_class_name = 3,
63 cpi_slot_target_class_name = 5,
64 cpi_slot_target_method_name = 7,
65 cpi_slot_target_method_name_sca = 9, // SerializationConstructorAccessor case, see above
66 cpi_slot_target_method_sig = 8,
67 cpi_slot_target_method_sig_sca = 10 // SerializationConstructorAccessor case, see above
68};
69
70// Returns a string, resource-area allocated, from an UTF8 slot in the constant pool in the
71// given Klass*.
72static const char* get_string_from_cp_with_checks(const InstanceKlass* k, int cpi) {
73 const char* s = NULL;
74 const ConstantPool* const cp = k->constants();
75
76 assert(cp != NULL, "No cp?");
77 assert(cp->is_within_bounds(cpi), "Unexpected constant pool layout for \"%s\", child class of Generated{Method|Constructor}AccessorImplXXX"
78 " (cpi %d out of bounds for [0..%d)).", k->external_name(), cpi, cp->length());
79 assert(cp->tag_at(cpi).is_utf8(), "Unexpected constant pool layout for \"%s\", child class of Generated{Method|Constructor}AccessorImplXXX"
80 " (no UTF8 at cpi %d (%u)).", k->external_name(), cpi, cp->tag_at(cpi).value());
81
82 // Be nice in release: lets not crash, just return NULL.
83 if (cp != NULL && cp->is_within_bounds(cpi) && cp->tag_at(cpi).is_utf8()) {
84 s = cp->symbol_at(cpi)->as_C_string();
85 }
86
87 return s;
88}
89
90// helper, returns true if class name of given class matches a given prefix
91static bool classname_matches_prefix(const Klass* k, const char* prefix) {
92 const char* classname = k->external_name();
93 if (classname != NULL) {
94 if (::strncmp(classname, prefix, strlen(prefix)) == 0) {
95 return true;
96 }
97 }
98 return false;
99}
100
101// Returns true if k is of type jdk/internal/reflect/GeneratedMethodAccessorXXX.
102bool ReflectionAccessorImplKlassHelper::is_generated_method_accessor(const InstanceKlass* k) {
103 return k->super() == SystemDictionary::reflect_MethodAccessorImpl_klass() &&
104 classname_matches_prefix(k, "jdk.internal.reflect.GeneratedMethodAccessor");
105}
106
107// Returns true if k is of type jdk/internal/reflect/GeneratedConstructorAccessorXXX.
108bool ReflectionAccessorImplKlassHelper::is_generated_constructor_accessor(const InstanceKlass* k) {
109 return k->super() == SystemDictionary::reflect_ConstructorAccessorImpl_klass() &&
110 classname_matches_prefix(k, "jdk.internal.reflect.GeneratedConstructorAccessor");
111}
112
113// Returns true if k is of type jdk/internal/reflect/GeneratedSerializationConstructorAccessorXXX.
114bool ReflectionAccessorImplKlassHelper::is_generated_method_serialization_constructor_accessor(const InstanceKlass* k) {
115 // GeneratedSerializationConstructorAccessor is not a direct subclass of ConstructorAccessorImpl
116 const Klass* sk = k->super();
117 if (sk != NULL && sk->super() == SystemDictionary::reflect_ConstructorAccessorImpl_klass() &&
118 classname_matches_prefix(k, "jdk.internal.reflect.GeneratedSerializationConstructorAccessor")) {
119 return true;
120 }
121 return false;
122}
123
124const char* ReflectionAccessorImplKlassHelper::get_target_class_name(const InstanceKlass* k) {
125 return get_string_from_cp_with_checks(k, cpi_slot_target_class_name);
126}
127
128const char* ReflectionAccessorImplKlassHelper::get_target_method_name(const InstanceKlass* k) {
129 const int target_method_name_cpi =
130 is_generated_method_serialization_constructor_accessor(k) ? cpi_slot_target_method_name_sca : cpi_slot_target_method_name;
131 return get_string_from_cp_with_checks(k, target_method_name_cpi);
132}
133
134const char* ReflectionAccessorImplKlassHelper::get_target_method_signature(const InstanceKlass* k) {
135 const int target_method_name_cpi =
136 is_generated_method_serialization_constructor_accessor(k) ? cpi_slot_target_method_sig_sca : cpi_slot_target_method_sig;
137 return get_string_from_cp_with_checks(k, target_method_name_cpi);
138}
139
140// Returns true if this is either one of jdk/internal/reflect/Generated{SerializationConstructor|Constructor|Method}AccessorXXX
141// and it is safe to call print_invocation_target(k)
142bool ReflectionAccessorImplKlassHelper::is_generated_accessor(const Klass* k) {
143 if (k != NULL && k->is_instance_klass()) {
144 const InstanceKlass* ik = InstanceKlass::cast(k);
145 if (ik->is_initialized()) {
146 return is_generated_method_accessor(ik) ||
147 is_generated_constructor_accessor(ik) ||
148 is_generated_method_serialization_constructor_accessor(ik);
149 }
150 }
151 return false;
152}
153void ReflectionAccessorImplKlassHelper::print_invocation_target(outputStream* out, Klass* k) {
154 assert(ReflectionAccessorImplKlassHelper::is_generated_accessor(k), "Invariant");
155 InstanceKlass* ik = InstanceKlass::cast(k);
156 ResourceMark rm;
157 const char* target_class_name = ReflectionAccessorImplKlassHelper::get_target_class_name(ik);
158 const char* target_method_name = ReflectionAccessorImplKlassHelper::get_target_method_name(ik);
159 const char* target_method_signature = ReflectionAccessorImplKlassHelper::get_target_method_signature(ik);
160 out->print("%s::%s %s",
161 target_class_name != NULL ? target_class_name : "?",
162 target_method_name != NULL ? target_method_name : "?",
163 target_method_signature != NULL ? target_method_signature : "?");
164}
165