1 /*
  2  * Copyright (c) 2003, 2021, 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_CLASSFILE_VERIFICATIONTYPE_HPP
 26 #define SHARE_CLASSFILE_VERIFICATIONTYPE_HPP
 27 
 28 #include "oops/instanceKlass.hpp"
 29 #include "oops/oop.hpp"
 30 #include "oops/symbol.hpp"
 31 #include "runtime/handles.hpp"
 32 #include "runtime/signature.hpp"
 33 
 34 enum {
 35   // As specifed in the JVM spec
 36   ITEM_Top = 0,
 37   ITEM_Integer = 1,
 38   ITEM_Float = 2,
 39   ITEM_Double = 3,
 40   ITEM_Long = 4,
 41   ITEM_Null = 5,
 42   ITEM_UninitializedThis = 6,
 43   ITEM_Object = 7,
 44   ITEM_Uninitialized = 8,
 45   ITEM_Bogus = (uint)-1
 46 };
 47 
 48 class ClassVerifier;
 49 
 50 class VerificationType {
 51   private:
 52     // Least significant bits of _handle are always 0, so we use these as
 53     // the indicator that the _handle is valid.  Otherwise, the _data field
 54     // contains encoded data (as specified below).  Should the VM change
 55     // and the lower bits on oops aren't 0, the assert in the constructor
 56     // will catch this and we'll have to add a descriminator tag to this
 57     // structure.
 58     union {
 59       Symbol*   _sym;
 60       uintptr_t _data;
 61     } _u;
 62 
 63     enum {
 64       // These rest are not found in classfiles, but used by the verifier
 65       ITEM_Boolean = 9, ITEM_Byte, ITEM_Short, ITEM_Char,
 66       ITEM_Long_2nd, ITEM_Double_2nd
 67     };
 68 
 69     // Enum for the _data field
 70     enum {
 71       // Bottom two bits determine if the type is a reference, primitive,
 72       // uninitialized or a query-type.
 73       TypeMask           = 0x00000003,
 74 
 75       // Topmost types encoding
 76       Reference          = 0x0,        // _sym contains the name
 77       Primitive          = 0x1,        // see below for primitive list
 78       Uninitialized      = 0x2,        // 0x00ffff00 contains bci
 79       TypeQuery          = 0x3,        // Meta-types used for category testing
 80 
 81       // Utility flags
 82       ReferenceFlag      = 0x00,       // For reference query types
 83       Category1Flag      = 0x01,       // One-word values
 84       Category2Flag      = 0x02,       // First word of a two-word value
 85       Category2_2ndFlag  = 0x04,       // Second word of a two-word value
 86 
 87       // special reference values
 88       Null               = 0x00000000, // A reference with a 0 sym is null
 89 
 90       // Primitives categories (the second byte determines the category)
 91       Category1          = (Category1Flag     << 1 * BitsPerByte) | Primitive,
 92       Category2          = (Category2Flag     << 1 * BitsPerByte) | Primitive,
 93       Category2_2nd      = (Category2_2ndFlag << 1 * BitsPerByte) | Primitive,
 94 
 95       // Primitive values (type descriminator stored in most-signifcant bytes)
 96       // Bogus needs the " | Primitive".  Else, is_reference(Bogus) returns TRUE.
 97       Bogus              = (ITEM_Bogus      << 2 * BitsPerByte) | Primitive,
 98       Boolean            = (ITEM_Boolean    << 2 * BitsPerByte) | Category1,
 99       Byte               = (ITEM_Byte       << 2 * BitsPerByte) | Category1,
100       Short              = (ITEM_Short      << 2 * BitsPerByte) | Category1,
101       Char               = (ITEM_Char       << 2 * BitsPerByte) | Category1,
102       Integer            = (ITEM_Integer    << 2 * BitsPerByte) | Category1,
103       Float              = (ITEM_Float      << 2 * BitsPerByte) | Category1,
104       Long               = (ITEM_Long       << 2 * BitsPerByte) | Category2,
105       Double             = (ITEM_Double     << 2 * BitsPerByte) | Category2,
106       Long_2nd           = (ITEM_Long_2nd   << 2 * BitsPerByte) | Category2_2nd,
107       Double_2nd         = (ITEM_Double_2nd << 2 * BitsPerByte) | Category2_2nd,
108 
109       // Used by Uninitialized (second and third bytes hold the bci)
110       BciMask            = 0xffff << 1 * BitsPerByte,
111       BciForThis         = ((u2)-1),   // A bci of -1 is an Unintialized-This
112 
113       // Query values
114       ReferenceQuery     = (ReferenceFlag     << 1 * BitsPerByte) | TypeQuery,
115       Category1Query     = (Category1Flag     << 1 * BitsPerByte) | TypeQuery,
116       Category2Query     = (Category2Flag     << 1 * BitsPerByte) | TypeQuery,
117       Category2_2ndQuery = (Category2_2ndFlag << 1 * BitsPerByte) | TypeQuery
118     };
119 
120   VerificationType(uintptr_t raw_data) {
121     _u._data = raw_data;
122   }
123 
124  public:
125 
126   VerificationType() { *this = bogus_type(); }
127 
128   // Create verification types
129   static VerificationType bogus_type() { return VerificationType(Bogus); }
130   static VerificationType top_type() { return bogus_type(); } // alias
131   static VerificationType null_type() { return VerificationType(Null); }
132   static VerificationType integer_type() { return VerificationType(Integer); }
133   static VerificationType float_type() { return VerificationType(Float); }
134   static VerificationType long_type() { return VerificationType(Long); }
135   static VerificationType long2_type() { return VerificationType(Long_2nd); }
136   static VerificationType double_type() { return VerificationType(Double); }
137   static VerificationType boolean_type() { return VerificationType(Boolean); }
138   static VerificationType byte_type() { return VerificationType(Byte); }
139   static VerificationType char_type() { return VerificationType(Char); }
140   static VerificationType short_type() { return VerificationType(Short); }
141   static VerificationType double2_type()
142     { return VerificationType(Double_2nd); }
143 
144   // "check" types are used for queries.  A "check" type is not assignable
145   // to anything, but the specified types are assignable to a "check".  For
146   // example, any category1 primitive is assignable to category1_check and
147   // any reference is assignable to reference_check.
148   static VerificationType reference_check()
149     { return VerificationType(ReferenceQuery); }
150   static VerificationType category1_check()
151     { return VerificationType(Category1Query); }
152   static VerificationType category2_check()
153     { return VerificationType(Category2Query); }
154   static VerificationType category2_2nd_check()
155     { return VerificationType(Category2_2ndQuery); }
156 
157   // For reference types, store the actual Symbol
158   static VerificationType reference_type(Symbol* sh) {
159       assert(((uintptr_t)sh & 0x3) == 0, "Symbols must be aligned");
160       // If the above assert fails in the future because oop* isn't aligned,
161       // then this type encoding system will have to change to have a tag value
162       // to descriminate between oops and primitives.
163       return VerificationType((uintptr_t)sh);
164   }
165   static VerificationType uninitialized_type(u2 bci)
166     { return VerificationType(bci << 1 * BitsPerByte | Uninitialized); }
167   static VerificationType uninitialized_this_type()
168     { return uninitialized_type(BciForThis); }
169 
170   // Create based on u1 read from classfile
171   static VerificationType from_tag(u1 tag);
172 
173   bool is_bogus() const     { return (_u._data == Bogus); }
174   bool is_null() const      { return (_u._data == Null); }
175   bool is_boolean() const   { return (_u._data == Boolean); }
176   bool is_byte() const      { return (_u._data == Byte); }
177   bool is_char() const      { return (_u._data == Char); }
178   bool is_short() const     { return (_u._data == Short); }
179   bool is_integer() const   { return (_u._data == Integer); }
180   bool is_long() const      { return (_u._data == Long); }
181   bool is_float() const     { return (_u._data == Float); }
182   bool is_double() const    { return (_u._data == Double); }
183   bool is_long2() const     { return (_u._data == Long_2nd); }
184   bool is_double2() const   { return (_u._data == Double_2nd); }
185   bool is_reference() const { return ((_u._data & TypeMask) == Reference); }
186   bool is_category1() const {
187     // This should return true for all one-word types, which are category1
188     // primitives, and references (including uninitialized refs).  Though
189     // the 'query' types should technically return 'false' here, if we
190     // allow this to return true, we can perform the test using only
191     // 2 operations rather than 8 (3 masks, 3 compares and 2 logical 'ands').
192     // Since noone should call this on a query type anyway, this is ok.
193     assert(!is_check(), "Must not be a check type (wrong value returned)");
194     return ((_u._data & Category1) != Primitive);
195     // should only return false if it's a primitive, and the category1 flag
196     // is not set.
197   }
198   bool is_category2() const { return ((_u._data & Category2) == Category2); }
199   bool is_category2_2nd() const {
200     return ((_u._data & Category2_2nd) == Category2_2nd);
201   }
202   bool is_reference_check() const { return _u._data == ReferenceQuery; }
203   bool is_category1_check() const { return _u._data == Category1Query; }
204   bool is_category2_check() const { return _u._data == Category2Query; }
205   bool is_category2_2nd_check() const { return _u._data == Category2_2ndQuery; }
206   bool is_check() const { return (_u._data & TypeQuery) == TypeQuery; }
207 
208   bool is_x_array(char sig) const {
209     return is_null() || (is_array() && (name()->char_at(1) == sig));
210   }
211   bool is_int_array() const { return is_x_array(JVM_SIGNATURE_INT); }
212   bool is_byte_array() const { return is_x_array(JVM_SIGNATURE_BYTE); }
213   bool is_bool_array() const { return is_x_array(JVM_SIGNATURE_BOOLEAN); }
214   bool is_char_array() const { return is_x_array(JVM_SIGNATURE_CHAR); }
215   bool is_short_array() const { return is_x_array(JVM_SIGNATURE_SHORT); }
216   bool is_long_array() const { return is_x_array(JVM_SIGNATURE_LONG); }
217   bool is_float_array() const { return is_x_array(JVM_SIGNATURE_FLOAT); }
218   bool is_double_array() const { return is_x_array(JVM_SIGNATURE_DOUBLE); }
219   bool is_object_array() const { return is_x_array(JVM_SIGNATURE_CLASS); }
220   bool is_array_array() const { return is_x_array(JVM_SIGNATURE_ARRAY); }
221   bool is_reference_array() const
222     { return is_object_array() || is_array_array(); }
223   bool is_object() const
224     { return (is_reference() && !is_null() && name()->utf8_length() >= 1 &&
225               name()->char_at(0) != JVM_SIGNATURE_ARRAY); }
226   bool is_array() const
227     { return (is_reference() && !is_null() && name()->utf8_length() >= 2 &&
228               name()->char_at(0) == JVM_SIGNATURE_ARRAY); }
229   bool is_uninitialized() const
230     { return ((_u._data & Uninitialized) == Uninitialized); }
231   bool is_uninitialized_this() const
232     { return is_uninitialized() && bci() == BciForThis; }
233 
234   VerificationType to_category2_2nd() const {
235     assert(is_category2(), "Must be a double word");
236     return VerificationType(is_long() ? Long_2nd : Double_2nd);
237   }
238 
239   u2 bci() const {
240     assert(is_uninitialized(), "Must be uninitialized type");
241     return ((_u._data & BciMask) >> 1 * BitsPerByte);
242   }
243 
244   Symbol* name() const {
245     assert(is_reference() && !is_null(), "Must be a non-null reference");
246     return _u._sym;
247   }
248 
249   bool equals(const VerificationType& t) const {
250     return (_u._data == t._u._data ||
251       (is_reference() && t.is_reference() && !is_null() && !t.is_null() &&
252        name() == t.name()));
253   }
254 
255   bool operator ==(const VerificationType& t) const {
256     return equals(t);
257   }
258 
259   bool operator !=(const VerificationType& t) const {
260     return !equals(t);
261   }
262 
263   // The whole point of this type system - check to see if one type
264   // is assignable to another.  Returns true if one can assign 'from' to
265   // this.
266   bool is_assignable_from(
267       const VerificationType& from, ClassVerifier* context,
268       bool from_field_is_protected, TRAPS) const {
269     if (equals(from) || is_bogus()) {
270       return true;
271     } else {
272       switch(_u._data) {
273         case Category1Query:
274           return from.is_category1();
275         case Category2Query:
276           return from.is_category2();
277         case Category2_2ndQuery:
278           return from.is_category2_2nd();
279         case ReferenceQuery:
280           return from.is_reference() || from.is_uninitialized();
281         case Boolean:
282         case Byte:
283         case Char:
284         case Short:
285           // An int can be assigned to boolean, byte, char or short values.
286           return from.is_integer();
287         default:
288           if (is_reference() && from.is_reference()) {
289             return is_reference_assignable_from(from, context,
290                                                 from_field_is_protected,
291                                                 THREAD);
292           } else {
293             return false;
294           }
295       }
296     }
297   }
298 
299   // Check to see if one array component type is assignable to another.
300   // Same as is_assignable_from() except int primitives must be identical.
301   bool is_component_assignable_from(
302       const VerificationType& from, ClassVerifier* context,
303       bool from_field_is_protected, TRAPS) const {
304     if (equals(from) || is_bogus()) {
305       return true;
306     } else {
307       switch(_u._data) {
308         case Boolean:
309         case Byte:
310         case Char:
311         case Short:
312           return false;
313         default:
314           return is_assignable_from(from, context, from_field_is_protected, THREAD);
315       }
316     }
317   }
318 
319   VerificationType get_component(ClassVerifier* context) const;
320 
321   int dimensions() const {
322     assert(is_array(), "Must be an array");
323     int index = 0;
324     while (name()->char_at(index) == JVM_SIGNATURE_ARRAY) index++;
325     return index;
326   }
327 
328   void print_on(outputStream* st) const;
329 
330  private:
331 
332   bool is_reference_assignable_from(
333     const VerificationType&, ClassVerifier*, bool from_field_is_protected,
334     TRAPS) const;
335 
336  public:
337   static bool resolve_and_check_assignability(InstanceKlass* klass, Symbol* name,
338                                               Symbol* from_name, bool from_field_is_protected,
339                                               bool from_is_array, bool from_is_object,
340                                               TRAPS);
341 };
342 
343 #endif // SHARE_CLASSFILE_VERIFICATIONTYPE_HPP