mcs/class/Mono.Cecil/Mono.Cecil.Cil/CodeReader.cs

   1 //
   2 // CodeReader.cs
   3 //
   4 // Author:
   5 //   Jb Evain (jbevain@gmail.com)
   6 //
   7 // Copyright (c) 2008 - 2010 Jb Evain
   8 //
   9 // Permission is hereby granted, free of charge, to any person obtaining
  10 // a copy of this software and associated documentation files (the
  11 // "Software"), to deal in the Software without restriction, including
  12 // without limitation the rights to use, copy, modify, merge, publish,
  13 // distribute, sublicense, and/or sell copies of the Software, and to
  14 // permit persons to whom the Software is furnished to do so, subject to
  15 // the following conditions:
  16 //
  17 // The above copyright notice and this permission notice shall be
  18 // included in all copies or substantial portions of the Software.
  19 //
  20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  21 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  22 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  23 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  24 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  25 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  26 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  27 //
  28
  29 using System;
  30
  31 using Mono.Cecil.PE;
  32 using Mono.Collections.Generic;
  33
  34 using RVA = System.UInt32;
  35
  36 namespace Mono.Cecil.Cil {
  37
  38         sealed class CodeReader : ByteBuffer {
  39
  40                 readonly internal MetadataReader reader;
  41
  42                 int start;
  43                 Section code_section;
  44
  45                 MethodDefinition method;
  46                 MethodBody body;
  47
  48                 int Offset {
  49                         get { return base.position - start; }
  50                 }
  51
  52                 CodeReader (Section section, MetadataReader reader)
  53                         : base (section.Data)
  54                 {
  55                         this.code_section = section;
  56                         this.reader = reader;
  57                 }
  58
  59                 public static CodeReader CreateCodeReader (MetadataReader metadata)
  60                 {
  61                         return new CodeReader (metadata.image.MetadataSection, metadata);
  62                 }
  63
  64                 public MethodBody ReadMethodBody (MethodDefinition method)
  65                 {
  66                         this.method = method;
  67                         this.body = new MethodBody (method);
  68
  69                         reader.context = method;
  70
  71                         ReadMethodBody ();
  72
  73                         return this.body;
  74                 }
  75
  76                 public void MoveTo (int rva)
  77                 {
  78                         if (!IsInSection (rva)) {
  79                                 code_section = reader.image.GetSectionAtVirtualAddress ((uint) rva);
  80                                 Reset (code_section.Data);
  81                         }
  82
  83                         base.position = rva - (int) code_section.VirtualAddress;
  84                 }
  85
  86                 bool IsInSection (int rva)
  87                 {
  88                         return code_section.VirtualAddress <= rva && rva < code_section.VirtualAddress + code_section.SizeOfRawData;
  89                 }
  90
  91                 void ReadMethodBody ()
  92                 {
  93                         MoveTo (method.RVA);
  94
  95                         var flags = ReadByte ();
  96                         switch (flags & 0x3) {
  97                         case 0x2: // tiny
  98                                 body.code_size = flags >> 2;
  99                                 body.MaxStackSize = 8;
 100                                 ReadCode ();
 101                                 break;
 102                         case 0x3: // fat
 103                                 base.position--;
 104                                 ReadFatMethod ();
 105                                 break;
 106                         default:
 107                                 throw new InvalidOperationException ();
 108                         }
 109
 110                         var symbol_reader = reader.module.SymbolReader;
 111
 112                         if (symbol_reader != null) {
 113                                 var instructions = body.Instructions;
 114                                 symbol_reader.Read (body, offset => GetInstruction (instructions, offset));
 115                         }
 116                 }
 117
 118                 void ReadFatMethod ()
 119                 {
 120                         var flags = ReadUInt16 ();
 121                         body.max_stack_size = ReadUInt16 ();
 122                         body.code_size = (int) ReadUInt32 ();
 123                         body.local_var_token = new MetadataToken (ReadUInt32 ());
 124                         body.init_locals = (flags & 0x10) != 0;
 125
 126                         if (body.local_var_token.RID != 0)
 127                                 body.variables = ReadVariables (body.local_var_token);
 128
 129                         ReadCode ();
 130
 131                         if ((flags & 0x8) != 0)
 132                                 ReadSection ();
 133                 }
 134
 135                 public VariableDefinitionCollection ReadVariables (MetadataToken local_var_token)
 136                 {
 137                         var position = reader.position;
 138                         var variables = reader.ReadVariables (local_var_token);
 139                         reader.position = position;
 140
 141                         return variables;
 142                 }
 143
 144                 void ReadCode ()
 145                 {
 146                         start = position;
 147                         var code_size = body.code_size;
 148
 149                         if (code_size < 0 || buffer.Length <= (uint) (code_size + position))
 150                                 code_size = 0;
 151
 152                         var end = start + code_size;
 153                         var instructions = body.instructions = new InstructionCollection (code_size / 3);
 154
 155                         while (position < end) {
 156                                 var offset = base.position - start;
 157                                 var opcode = ReadOpCode ();
 158                                 var current = new Instruction (offset, opcode);
 159
 160                                 if (opcode.OperandType != OperandType.InlineNone)
 161                                         current.operand = ReadOperand (current);
 162
 163                                 instructions.Add (current);
 164                         }
 165
 166                         ResolveBranches (instructions);
 167                 }
 168
 169                 OpCode ReadOpCode ()
 170                 {
 171                         var il_opcode = ReadByte ();
 172                         return il_opcode != 0xfe
 173                                 ? OpCodes.OneByteOpCode [il_opcode]
 174                                 : OpCodes.TwoBytesOpCode [ReadByte ()];
 175                 }
 176
 177                 object ReadOperand (Instruction instruction)
 178                 {
 179                         switch (instruction.opcode.OperandType) {
 180                         case OperandType.InlineSwitch:
 181                                 var length = ReadInt32 ();
 182                                 var base_offset = Offset + (4 * length);
 183                                 var branches = new int [length];
 184                                 for (int i = 0; i < length; i++)
 185                                         branches [i] = base_offset + ReadInt32 ();
 186                                 return branches;
 187                         case OperandType.ShortInlineBrTarget:
 188                                 return ReadSByte () + Offset;
 189                         case OperandType.InlineBrTarget:
 190                                 return ReadInt32 () + Offset;
 191                         case OperandType.ShortInlineI:
 192                                 if (instruction.opcode == OpCodes.Ldc_I4_S)
 193                                         return ReadSByte ();
 194
 195                                 return ReadByte ();
 196                         case OperandType.InlineI:
 197                                 return ReadInt32 ();
 198                         case OperandType.ShortInlineR:
 199                                 return ReadSingle ();
 200                         case OperandType.InlineR:
 201                                 return ReadDouble ();
 202                         case OperandType.InlineI8:
 203                                 return ReadInt64 ();
 204                         case OperandType.ShortInlineVar:
 205                                 return GetVariable (ReadByte ());
 206                         case OperandType.InlineVar:
 207                                 return GetVariable (ReadUInt16 ());
 208                         case OperandType.ShortInlineArg:
 209                                 return GetParameter (ReadByte ());
 210                         case OperandType.InlineArg:
 211                                 return GetParameter (ReadUInt16 ());
 212                         case OperandType.InlineSig:
 213                                 return GetCallSite (ReadToken ());
 214                         case OperandType.InlineString:
 215                                 return GetString (ReadToken ());
 216                         case OperandType.InlineTok:
 217                         case OperandType.InlineType:
 218                         case OperandType.InlineMethod:
 219                         case OperandType.InlineField:
 220                                 return reader.LookupToken (ReadToken ());
 221                         default:
 222                                 throw new NotSupportedException ();
 223                         }
 224                 }
 225
 226                 public string GetString (MetadataToken token)
 227                 {
 228                         return reader.image.UserStringHeap.Read (token.RID);
 229                 }
 230
 231                 public ParameterDefinition GetParameter (int index)
 232                 {
 233                         return body.GetParameter (index);
 234                 }
 235
 236                 public VariableDefinition GetVariable (int index)
 237                 {
 238                         return body.GetVariable (index);
 239                 }
 240
 241                 public CallSite GetCallSite (MetadataToken token)
 242                 {
 243                         return reader.ReadCallSite (token);
 244                 }
 245
 246                 void ResolveBranches (Collection<Instruction> instructions)
 247                 {
 248                         var items = instructions.items;
 249                         var size = instructions.size;
 250
 251                         for (int i = 0; i < size; i++) {
 252                                 var instruction = items [i];
 253                                 switch (instruction.opcode.OperandType) {
 254                                 case OperandType.ShortInlineBrTarget:
 255                                 case OperandType.InlineBrTarget:
 256                                         instruction.operand = GetInstruction ((int) instruction.operand);
 257                                         break;
 258                                 case OperandType.InlineSwitch:
 259                                         var offsets = (int []) instruction.operand;
 260                                         var branches = new Instruction [offsets.Length];
 261                                         for (int j = 0; j < offsets.Length; j++)
 262                                                 branches [j] = GetInstruction (offsets [j]);
 263
 264                                         instruction.operand = branches;
 265                                         break;
 266                                 }
 267                         }
 268                 }
 269
 270                 Instruction GetInstruction (int offset)
 271                 {
 272                         return GetInstruction (body.Instructions, offset);
 273                 }
 274
 275                 static Instruction GetInstruction (Collection<Instruction> instructions, int offset)
 276                 {
 277                         var size = instructions.size;
 278                         var items = instructions.items;
 279                         if (offset < 0 || offset > items [size - 1].offset)
 280                                 return null;
 281
 282                         int min = 0;
 283                         int max = size - 1;
 284                         while (min <= max) {
 285                                 int mid = min + ((max - min) / 2);
 286                                 var instruction = items [mid];
 287                                 var instruction_offset = instruction.offset;
 288
 289                                 if (offset == instruction_offset)
 290                                         return instruction;
 291
 292                                 if (offset < instruction_offset)
 293                                         max = mid - 1;
 294                                 else
 295                                         min = mid + 1;
 296                         }
 297
 298                         return null;
 299                 }
 300
 301                 void ReadSection ()
 302                 {
 303                         Align (4);
 304
 305                         const byte fat_format = 0x40;
 306                         const byte more_sects = 0x80;
 307
 308                         var flags = ReadByte ();
 309                         if ((flags & fat_format) == 0)
 310                                 ReadSmallSection ();
 311                         else
 312                                 ReadFatSection ();
 313
 314                         if ((flags & more_sects) != 0)
 315                                 ReadSection ();
 316                 }
 317
 318                 void ReadSmallSection ()
 319                 {
 320                         var count = ReadByte () / 12;
 321                         Advance (2);
 322
 323                         ReadExceptionHandlers (
 324                                 count,
 325                                 () => (int) ReadUInt16 (),
 326                                 () => (int) ReadByte ());
 327                 }
 328
 329                 void ReadFatSection ()
 330                 {
 331                         position--;
 332                         var count = (ReadInt32 () >> 8) / 24;
 333
 334                         ReadExceptionHandlers (
 335                                 count,
 336                                 ReadInt32,
 337                                 ReadInt32);
 338                 }
 339
 340                 // inline ?
 341                 void ReadExceptionHandlers (int count, Func<int> read_entry, Func<int> read_length)
 342                 {
 343                         for (int i = 0; i < count; i++) {
 344                                 var handler = new ExceptionHandler (
 345                                         (ExceptionHandlerType) (read_entry () & 0x7));
 346
 347                                 handler.TryStart = GetInstruction (read_entry ());
 348                                 handler.TryEnd = GetInstruction (handler.TryStart.Offset + read_length ());
 349
 350                                 handler.HandlerStart = GetInstruction (read_entry ());
 351                                 handler.HandlerEnd = GetInstruction (handler.HandlerStart.Offset + read_length ());
 352
 353                                 ReadExceptionHandlerSpecific (handler);
 354
 355                                 this.body.ExceptionHandlers.Add (handler);
 356                         }
 357                 }
 358
 359                 void ReadExceptionHandlerSpecific (ExceptionHandler handler)
 360                 {
 361                         switch (handler.HandlerType) {
 362                         case ExceptionHandlerType.Catch:
 363                                 handler.CatchType = (TypeReference) reader.LookupToken (ReadToken ());
 364                                 break;
 365                         case ExceptionHandlerType.Filter:
 366                                 handler.FilterStart = GetInstruction (ReadInt32 ());
 367                                 handler.FilterEnd = handler.HandlerStart.Previous;
 368                                 break;
 369                         default:
 370                                 Advance (4);
 371                                 break;
 372                         }
 373                 }
 374
 375                 void Align (int align)
 376                 {
 377                         align--;
 378                         Advance (((position + align) & ~align) - position);
 379                 }
 380
 381                 public MetadataToken ReadToken ()
 382                 {
 383                         return new MetadataToken (ReadUInt32 ());
 384                 }
 385
 386 #if !READ_ONLY
 387
 388                 public ByteBuffer PatchRawMethodBody (MethodDefinition method, CodeWriter writer, out MethodSymbols symbols)
 389                 {
 390                         var buffer = new ByteBuffer ();
 391                         symbols = new MethodSymbols (method.Name);
 392
 393                         this.method = method;
 394                         reader.context = method;
 395
 396                         MoveTo (method.RVA);
 397
 398                         var flags = ReadByte ();
 399
 400                         MetadataToken local_var_token;
 401
 402                         switch (flags & 0x3) {
 403                         case 0x2: // tiny
 404                                 buffer.WriteByte (flags);
 405                                 local_var_token = MetadataToken.Zero;
 406                                 symbols.code_size = flags >> 2;
 407                                 PatchRawCode (buffer, symbols.code_size, writer);
 408                                 break;
 409                         case 0x3: // fat
 410                                 base.position--;
 411
 412                                 PatchRawFatMethod (buffer, symbols, writer, out local_var_token);
 413                                 break;
 414                         default:
 415                                 throw new NotSupportedException ();
 416                         }
 417
 418                         var symbol_reader = reader.module.SymbolReader;
 419                         if (symbol_reader != null && writer.metadata.write_symbols) {
 420                                 symbols.method_token = GetOriginalToken (writer.metadata, method);
 421                                 symbols.local_var_token = local_var_token;
 422                                 symbol_reader.Read (symbols);
 423                         }
 424
 425                         return buffer;
 426                 }
 427
 428                 void PatchRawFatMethod (ByteBuffer buffer, MethodSymbols symbols, CodeWriter writer, out MetadataToken local_var_token)
 429                 {
 430                         var flags = ReadUInt16 ();
 431                         buffer.WriteUInt16 (flags);
 432                         buffer.WriteUInt16 (ReadUInt16 ());
 433                         symbols.code_size = ReadInt32 ();
 434                         buffer.WriteInt32 (symbols.code_size);
 435                         local_var_token = ReadToken ();
 436
 437                         if (local_var_token.RID > 0) {
 438                                 var variables = symbols.variables = ReadVariables (local_var_token);
 439                                 buffer.WriteUInt32 (variables != null
 440                                         ? writer.GetStandAloneSignature (symbols.variables).ToUInt32 ()
 441                                         : 0);
 442                         } else
 443                                 buffer.WriteUInt32 (0);
 444
 445                         PatchRawCode (buffer, symbols.code_size, writer);
 446
 447                         if ((flags & 0x8) != 0)
 448                                 PatchRawSection (buffer, writer.metadata);
 449                 }
 450
 451                 static MetadataToken GetOriginalToken (MetadataBuilder metadata, MethodDefinition method)
 452                 {
 453                         MetadataToken original;
 454                         if (metadata.TryGetOriginalMethodToken (method.token, out original))
 455                                 return original;
 456
 457                         return MetadataToken.Zero;
 458                 }
 459
 460                 void PatchRawCode (ByteBuffer buffer, int code_size, CodeWriter writer)
 461                 {
 462                         var metadata = writer.metadata;
 463                         buffer.WriteBytes (ReadBytes (code_size));
 464                         var end = buffer.position;
 465                         buffer.position -= code_size;
 466
 467                         while (buffer.position < end) {
 468                                 OpCode opcode;
 469                                 var il_opcode = buffer.ReadByte ();
 470                                 if (il_opcode != 0xfe) {
 471                                         opcode = OpCodes.OneByteOpCode [il_opcode];
 472                                 } else {
 473                                         var il_opcode2 = buffer.ReadByte ();
 474                                         opcode = OpCodes.TwoBytesOpCode [il_opcode2];
 475                                 }
 476
 477                                 switch (opcode.OperandType) {
 478                                 case OperandType.ShortInlineI:
 479                                 case OperandType.ShortInlineBrTarget:
 480                                 case OperandType.ShortInlineVar:
 481                                 case OperandType.ShortInlineArg:
 482                                         buffer.position += 1;
 483                                         break;
 484                                 case OperandType.InlineVar:
 485                                 case OperandType.InlineArg:
 486                                         buffer.position += 2;
 487                                         break;
 488                                 case OperandType.InlineBrTarget:
 489                                 case OperandType.ShortInlineR:
 490                                 case OperandType.InlineI:
 491                                         buffer.position += 4;
 492                                         break;
 493                                 case OperandType.InlineI8:
 494                                 case OperandType.InlineR:
 495                                         buffer.position += 8;
 496                                         break;
 497                                 case OperandType.InlineSwitch:
 498                                         var length = buffer.ReadInt32 ();
 499                                         buffer.position += length * 4;
 500                                         break;
 501                                 case OperandType.InlineString:
 502                                         var @string = GetString (new MetadataToken (buffer.ReadUInt32 ()));
 503                                         buffer.position -= 4;
 504                                         buffer.WriteUInt32 (
 505                                                 new MetadataToken (
 506                                                         TokenType.String,
 507                                                         metadata.user_string_heap.GetStringIndex (@string)).ToUInt32 ());
 508                                         break;
 509                                 case OperandType.InlineSig:
 510                                         var call_site = GetCallSite (new MetadataToken (buffer.ReadUInt32 ()));
 511                                         buffer.position -= 4;
 512                                         buffer.WriteUInt32 (writer.GetStandAloneSignature (call_site).ToUInt32 ());
 513                                         break;
 514                                 case OperandType.InlineTok:
 515                                 case OperandType.InlineType:
 516                                 case OperandType.InlineMethod:
 517                                 case OperandType.InlineField:
 518                                         var provider = reader.LookupToken (new MetadataToken (buffer.ReadUInt32 ()));
 519                                         buffer.position -= 4;
 520                                         buffer.WriteUInt32 (metadata.LookupToken (provider).ToUInt32 ());
 521                                         break;
 522                                 }
 523                         }
 524                 }
 525
 526                 void PatchRawSection (ByteBuffer buffer, MetadataBuilder metadata)
 527                 {
 528                         var position = base.position;
 529                         Align (4);
 530                         buffer.WriteBytes (base.position - position);
 531
 532                         const byte fat_format = 0x40;
 533                         const byte more_sects = 0x80;
 534
 535                         var flags = ReadByte ();
 536                         if ((flags & fat_format) == 0) {
 537                                 buffer.WriteByte (flags);
 538                                 PatchRawSmallSection (buffer, metadata);
 539                         } else
 540                                 PatchRawFatSection (buffer, metadata);
 541
 542                         if ((flags & more_sects) != 0)
 543                                 PatchRawSection (buffer, metadata);
 544                 }
 545
 546                 void PatchRawSmallSection (ByteBuffer buffer, MetadataBuilder metadata)
 547                 {
 548                         var length = ReadByte ();
 549                         buffer.WriteByte (length);
 550                         Advance (2);
 551
 552                         buffer.WriteUInt16 (0);
 553
 554                         var count = length / 12;
 555
 556                         PatchRawExceptionHandlers (buffer, metadata, count, false);
 557                 }
 558
 559                 void PatchRawFatSection (ByteBuffer buffer, MetadataBuilder metadata)
 560                 {
 561                         position--;
 562                         var length = ReadInt32 ();
 563                         buffer.WriteInt32 (length);
 564
 565                         var count = (length >> 8) / 24;
 566
 567                         PatchRawExceptionHandlers (buffer, metadata, count, true);
 568                 }
 569
 570                 void PatchRawExceptionHandlers (ByteBuffer buffer, MetadataBuilder metadata, int count, bool fat_entry)
 571                 {
 572                         const int fat_entry_size = 16;
 573                         const int small_entry_size = 6;
 574
 575                         for (int i = 0; i < count; i++) {
 576                                 ExceptionHandlerType handler_type;
 577                                 if (fat_entry) {
 578                                         var type = ReadUInt32 ();
 579                                         handler_type = (ExceptionHandlerType) (type & 0x7);
 580                                         buffer.WriteUInt32 (type);
 581                                 } else {
 582                                         var type = ReadUInt16 ();
 583                                         handler_type = (ExceptionHandlerType) (type & 0x7);
 584                                         buffer.WriteUInt16 (type);
 585                                 }
 586
 587                                 buffer.WriteBytes (ReadBytes (fat_entry ? fat_entry_size : small_entry_size));
 588
 589                                 switch (handler_type) {
 590                                 case ExceptionHandlerType.Catch:
 591                                         var exception = reader.LookupToken (ReadToken ());
 592                                         buffer.WriteUInt32 (metadata.LookupToken (exception).ToUInt32 ());
 593                                         break;
 594                                 default:
 595                                         buffer.WriteUInt32 (ReadUInt32 ());
 596                                         break;
 597                                 }
 598                         }
 599                 }
 600
 601 #endif
 602
 603         }
 604 }