1/*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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24
25#ifndef SHARE_CLASSFILE_VERIFICATIONTYPE_HPP
26#define SHARE_CLASSFILE_VERIFICATIONTYPE_HPP
27
28#include "classfile/systemDictionary.hpp"
29#include "oops/instanceKlass.hpp"
30#include "oops/oop.hpp"
31#include "oops/symbol.hpp"
32#include "runtime/handles.hpp"
33#include "runtime/signature.hpp"
34
35enum {
36 // As specifed in the JVM spec
37 ITEM_Top = 0,
38 ITEM_Integer = 1,
39 ITEM_Float = 2,
40 ITEM_Double = 3,
41 ITEM_Long = 4,
42 ITEM_Null = 5,
43 ITEM_UninitializedThis = 6,
44 ITEM_Object = 7,
45 ITEM_Uninitialized = 8,
46 ITEM_Bogus = (uint)-1
47};
48
49class ClassVerifier;
50
51class VerificationType {
52 private:
53 // Least significant bits of _handle are always 0, so we use these as
54 // the indicator that the _handle is valid. Otherwise, the _data field
55 // contains encoded data (as specified below). Should the VM change
56 // and the lower bits on oops aren't 0, the assert in the constructor
57 // will catch this and we'll have to add a descriminator tag to this
58 // structure.
59 union {
60 Symbol* _sym;
61 uintptr_t _data;
62 } _u;
63
64 enum {
65 // These rest are not found in classfiles, but used by the verifier
66 ITEM_Boolean = 9, ITEM_Byte, ITEM_Short, ITEM_Char,
67 ITEM_Long_2nd, ITEM_Double_2nd
68 };
69
70 // Enum for the _data field
71 enum {
72 // Bottom two bits determine if the type is a reference, primitive,
73 // uninitialized or a query-type.
74 TypeMask = 0x00000003,
75
76 // Topmost types encoding
77 Reference = 0x0, // _sym contains the name
78 Primitive = 0x1, // see below for primitive list
79 Uninitialized = 0x2, // 0x00ffff00 contains bci
80 TypeQuery = 0x3, // Meta-types used for category testing
81
82 // Utility flags
83 ReferenceFlag = 0x00, // For reference query types
84 Category1Flag = 0x01, // One-word values
85 Category2Flag = 0x02, // First word of a two-word value
86 Category2_2ndFlag = 0x04, // Second word of a two-word value
87
88 // special reference values
89 Null = 0x00000000, // A reference with a 0 sym is null
90
91 // Primitives categories (the second byte determines the category)
92 Category1 = (Category1Flag << 1 * BitsPerByte) | Primitive,
93 Category2 = (Category2Flag << 1 * BitsPerByte) | Primitive,
94 Category2_2nd = (Category2_2ndFlag << 1 * BitsPerByte) | Primitive,
95
96 // Primitive values (type descriminator stored in most-signifcant bytes)
97 // Bogus needs the " | Primitive". Else, is_reference(Bogus) returns TRUE.
98 Bogus = (ITEM_Bogus << 2 * BitsPerByte) | Primitive,
99 Boolean = (ITEM_Boolean << 2 * BitsPerByte) | Category1,
100 Byte = (ITEM_Byte << 2 * BitsPerByte) | Category1,
101 Short = (ITEM_Short << 2 * BitsPerByte) | Category1,
102 Char = (ITEM_Char << 2 * BitsPerByte) | Category1,
103 Integer = (ITEM_Integer << 2 * BitsPerByte) | Category1,
104 Float = (ITEM_Float << 2 * BitsPerByte) | Category1,
105 Long = (ITEM_Long << 2 * BitsPerByte) | Category2,
106 Double = (ITEM_Double << 2 * BitsPerByte) | Category2,
107 Long_2nd = (ITEM_Long_2nd << 2 * BitsPerByte) | Category2_2nd,
108 Double_2nd = (ITEM_Double_2nd << 2 * BitsPerByte) | Category2_2nd,
109
110 // Used by Uninitialized (second and third bytes hold the bci)
111 BciMask = 0xffff << 1 * BitsPerByte,
112 BciForThis = ((u2)-1), // A bci of -1 is an Unintialized-This
113
114 // Query values
115 ReferenceQuery = (ReferenceFlag << 1 * BitsPerByte) | TypeQuery,
116 Category1Query = (Category1Flag << 1 * BitsPerByte) | TypeQuery,
117 Category2Query = (Category2Flag << 1 * BitsPerByte) | TypeQuery,
118 Category2_2ndQuery = (Category2_2ndFlag << 1 * BitsPerByte) | TypeQuery
119 };
120
121 VerificationType(uintptr_t raw_data) {
122 _u._data = raw_data;
123 }
124
125 public:
126
127 VerificationType() { *this = bogus_type(); }
128
129 // Create verification types
130 static VerificationType bogus_type() { return VerificationType(Bogus); }
131 static VerificationType top_type() { return bogus_type(); } // alias
132 static VerificationType null_type() { return VerificationType(Null); }
133 static VerificationType integer_type() { return VerificationType(Integer); }
134 static VerificationType float_type() { return VerificationType(Float); }
135 static VerificationType long_type() { return VerificationType(Long); }
136 static VerificationType long2_type() { return VerificationType(Long_2nd); }
137 static VerificationType double_type() { return VerificationType(Double); }
138 static VerificationType boolean_type() { return VerificationType(Boolean); }
139 static VerificationType byte_type() { return VerificationType(Byte); }
140 static VerificationType char_type() { return VerificationType(Char); }
141 static VerificationType short_type() { return VerificationType(Short); }
142 static VerificationType double2_type()
143 { return VerificationType(Double_2nd); }
144
145 // "check" types are used for queries. A "check" type is not assignable
146 // to anything, but the specified types are assignable to a "check". For
147 // example, any category1 primitive is assignable to category1_check and
148 // any reference is assignable to reference_check.
149 static VerificationType reference_check()
150 { return VerificationType(ReferenceQuery); }
151 static VerificationType category1_check()
152 { return VerificationType(Category1Query); }
153 static VerificationType category2_check()
154 { return VerificationType(Category2Query); }
155 static VerificationType category2_2nd_check()
156 { return VerificationType(Category2_2ndQuery); }
157
158 // For reference types, store the actual Symbol
159 static VerificationType reference_type(Symbol* sh) {
160 assert(((uintptr_t)sh & 0x3) == 0, "Symbols must be aligned");
161 // If the above assert fails in the future because oop* isn't aligned,
162 // then this type encoding system will have to change to have a tag value
163 // to descriminate between oops and primitives.
164 return VerificationType((uintptr_t)sh);
165 }
166 static VerificationType uninitialized_type(u2 bci)
167 { return VerificationType(bci << 1 * BitsPerByte | Uninitialized); }
168 static VerificationType uninitialized_this_type()
169 { return uninitialized_type(BciForThis); }
170
171 // Create based on u1 read from classfile
172 static VerificationType from_tag(u1 tag);
173
174 bool is_bogus() const { return (_u._data == Bogus); }
175 bool is_null() const { return (_u._data == Null); }
176 bool is_boolean() const { return (_u._data == Boolean); }
177 bool is_byte() const { return (_u._data == Byte); }
178 bool is_char() const { return (_u._data == Char); }
179 bool is_short() const { return (_u._data == Short); }
180 bool is_integer() const { return (_u._data == Integer); }
181 bool is_long() const { return (_u._data == Long); }
182 bool is_float() const { return (_u._data == Float); }
183 bool is_double() const { return (_u._data == Double); }
184 bool is_long2() const { return (_u._data == Long_2nd); }
185 bool is_double2() const { return (_u._data == Double_2nd); }
186 bool is_reference() const { return ((_u._data & TypeMask) == Reference); }
187 bool is_category1() const {
188 // This should return true for all one-word types, which are category1
189 // primitives, and references (including uninitialized refs). Though
190 // the 'query' types should technically return 'false' here, if we
191 // allow this to return true, we can perform the test using only
192 // 2 operations rather than 8 (3 masks, 3 compares and 2 logical 'ands').
193 // Since noone should call this on a query type anyway, this is ok.
194 assert(!is_check(), "Must not be a check type (wrong value returned)");
195 return ((_u._data & Category1) != Primitive);
196 // should only return false if it's a primitive, and the category1 flag
197 // is not set.
198 }
199 bool is_category2() const { return ((_u._data & Category2) == Category2); }
200 bool is_category2_2nd() const {
201 return ((_u._data & Category2_2nd) == Category2_2nd);
202 }
203 bool is_reference_check() const { return _u._data == ReferenceQuery; }
204 bool is_category1_check() const { return _u._data == Category1Query; }
205 bool is_category2_check() const { return _u._data == Category2Query; }
206 bool is_category2_2nd_check() const { return _u._data == Category2_2ndQuery; }
207 bool is_check() const { return (_u._data & TypeQuery) == TypeQuery; }
208
209 bool is_x_array(char sig) const {
210 return is_null() || (is_array() && (name()->char_at(1) == sig));
211 }
212 bool is_int_array() const { return is_x_array('I'); }
213 bool is_byte_array() const { return is_x_array('B'); }
214 bool is_bool_array() const { return is_x_array('Z'); }
215 bool is_char_array() const { return is_x_array('C'); }
216 bool is_short_array() const { return is_x_array('S'); }
217 bool is_long_array() const { return is_x_array('J'); }
218 bool is_float_array() const { return is_x_array('F'); }
219 bool is_double_array() const { return is_x_array('D'); }
220 bool is_object_array() const { return is_x_array('L'); }
221 bool is_array_array() const { return is_x_array('['); }
222 bool is_reference_array() const
223 { return is_object_array() || is_array_array(); }
224 bool is_object() const
225 { return (is_reference() && !is_null() && name()->utf8_length() >= 1 &&
226 name()->char_at(0) != '['); }
227 bool is_array() const
228 { return (is_reference() && !is_null() && name()->utf8_length() >= 2 &&
229 name()->char_at(0) == '['); }
230 bool is_uninitialized() const
231 { return ((_u._data & Uninitialized) == Uninitialized); }
232 bool is_uninitialized_this() const
233 { return is_uninitialized() && bci() == BciForThis; }
234
235 VerificationType to_category2_2nd() const {
236 assert(is_category2(), "Must be a double word");
237 return VerificationType(is_long() ? Long_2nd : Double_2nd);
238 }
239
240 u2 bci() const {
241 assert(is_uninitialized(), "Must be uninitialized type");
242 return ((_u._data & BciMask) >> 1 * BitsPerByte);
243 }
244
245 Symbol* name() const {
246 assert(is_reference() && !is_null(), "Must be a non-null reference");
247 return _u._sym;
248 }
249
250 bool equals(const VerificationType& t) const {
251 return (_u._data == t._u._data ||
252 (is_reference() && t.is_reference() && !is_null() && !t.is_null() &&
253 name() == t.name()));
254 }
255
256 bool operator ==(const VerificationType& t) const {
257 return equals(t);
258 }
259
260 bool operator !=(const VerificationType& t) const {
261 return !equals(t);
262 }
263
264 // The whole point of this type system - check to see if one type
265 // is assignable to another. Returns true if one can assign 'from' to
266 // this.
267 bool is_assignable_from(
268 const VerificationType& from, ClassVerifier* context,
269 bool from_field_is_protected, TRAPS) const {
270 if (equals(from) || is_bogus()) {
271 return true;
272 } else {
273 switch(_u._data) {
274 case Category1Query:
275 return from.is_category1();
276 case Category2Query:
277 return from.is_category2();
278 case Category2_2ndQuery:
279 return from.is_category2_2nd();
280 case ReferenceQuery:
281 return from.is_reference() || from.is_uninitialized();
282 case Boolean:
283 case Byte:
284 case Char:
285 case Short:
286 // An int can be assigned to boolean, byte, char or short values.
287 return from.is_integer();
288 default:
289 if (is_reference() && from.is_reference()) {
290 return is_reference_assignable_from(from, context,
291 from_field_is_protected,
292 THREAD);
293 } else {
294 return false;
295 }
296 }
297 }
298 }
299
300 // Check to see if one array component type is assignable to another.
301 // Same as is_assignable_from() except int primitives must be identical.
302 bool is_component_assignable_from(
303 const VerificationType& from, ClassVerifier* context,
304 bool from_field_is_protected, TRAPS) const {
305 if (equals(from) || is_bogus()) {
306 return true;
307 } else {
308 switch(_u._data) {
309 case Boolean:
310 case Byte:
311 case Char:
312 case Short:
313 return false;
314 default:
315 return is_assignable_from(from, context, from_field_is_protected, THREAD);
316 }
317 }
318 }
319
320 VerificationType get_component(ClassVerifier* context, TRAPS) const;
321
322 int dimensions() const {
323 assert(is_array(), "Must be an array");
324 int index = 0;
325 while (name()->char_at(index) == '[') index++;
326 return index;
327 }
328
329 void print_on(outputStream* st) const;
330
331 private:
332
333 bool is_reference_assignable_from(
334 const VerificationType&, ClassVerifier*, bool from_field_is_protected,
335 TRAPS) const;
336
337 public:
338 static bool resolve_and_check_assignability(InstanceKlass* klass, Symbol* name,
339 Symbol* from_name, bool from_field_is_protected,
340 bool from_is_array, bool from_is_object,
341 TRAPS);
342};
343
344#endif // SHARE_CLASSFILE_VERIFICATIONTYPE_HPP
345