gold/reloc.h

   1 // reloc.h -- relocate input files for gold   -*- C++ -*-
   2
   3 // Copyright 2006, 2007 Free Software Foundation, Inc.
   4 // Written by Ian Lance Taylor <iant@google.com>.
   5
   6 // This file is part of gold.
   7
   8 // This program is free software; you can redistribute it and/or modify
   9 // it under the terms of the GNU General Public License as published by
  10 // the Free Software Foundation; either version 3 of the License, or
  11 // (at your option) any later version.
  12
  13 // This program is distributed in the hope that it will be useful,
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 // GNU General Public License for more details.
  17
  18 // You should have received a copy of the GNU General Public License
  19 // along with this program; if not, write to the Free Software
  20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  21 // MA 02110-1301, USA.
  22
  23 #ifndef GOLD_RELOC_H
  24 #define GOLD_RELOC_H
  25
  26 #include <byteswap.h>
  27
  28 #include "elfcpp.h"
  29 #include "workqueue.h"
  30
  31 namespace gold
  32 {
  33
  34 class General_options;
  35 class Object;
  36 class Relobj;
  37 class Read_relocs_data;
  38 class Symbol;
  39 class Layout;
  40 class Output_section;
  41
  42 template<int size>
  43 class Sized_symbol;
  44
  45 template<int size, bool big_endian>
  46 class Sized_relobj;
  47
  48 template<int size>
  49 class Symbol_value;
  50
  51 template<int sh_type, bool dynamic, int size, bool big_endian>
  52 class Output_data_reloc;
  53
  54 // A class to read the relocations for an object file, and then queue
  55 // up a task to see if they require any GOT/PLT/COPY relocations in
  56 // the symbol table.
  57
  58 class Read_relocs : public Task
  59 {
  60  public:
  61   // SYMTAB_LOCK is used to lock the symbol table.  BLOCKER should be
  62   // unblocked when the Scan_relocs task completes.
  63   Read_relocs(const General_options& options, Symbol_table* symtab,
  64               Layout* layout, Relobj* object, Task_token* symtab_lock,
  65               Task_token* blocker)
  66     : options_(options), symtab_(symtab), layout_(layout), object_(object),
  67       symtab_lock_(symtab_lock), blocker_(blocker)
  68   { }
  69
  70   // The standard Task methods.
  71
  72   Is_runnable_type
  73   is_runnable(Workqueue*);
  74
  75   Task_locker*
  76   locks(Workqueue*);
  77
  78   void
  79   run(Workqueue*);
  80
  81  private:
  82   const General_options& options_;
  83   Symbol_table* symtab_;
  84   Layout* layout_;
  85   Relobj* object_;
  86   Task_token* symtab_lock_;
  87   Task_token* blocker_;
  88 };
  89
  90 // Scan the relocations for an object to see if they require any
  91 // GOT/PLT/COPY relocations.
  92
  93 class Scan_relocs : public Task
  94 {
  95  public:
  96   // SYMTAB_LOCK is used to lock the symbol table.  BLOCKER should be
  97   // unblocked when the task completes.
  98   Scan_relocs(const General_options& options, Symbol_table* symtab,
  99               Layout* layout, Relobj* object, Read_relocs_data* rd,
 100               Task_token* symtab_lock, Task_token* blocker)
 101     : options_(options), symtab_(symtab), layout_(layout), object_(object),
 102       rd_(rd), symtab_lock_(symtab_lock), blocker_(blocker)
 103   { }
 104
 105   // The standard Task methods.
 106
 107   Is_runnable_type
 108   is_runnable(Workqueue*);
 109
 110   Task_locker*
 111   locks(Workqueue*);
 112
 113   void
 114   run(Workqueue*);
 115
 116  private:
 117   class Scan_relocs_locker;
 118
 119   const General_options& options_;
 120   Symbol_table* symtab_;
 121   Layout* layout_;
 122   Relobj* object_;
 123   Read_relocs_data* rd_;
 124   Task_token* symtab_lock_;
 125   Task_token* blocker_;
 126 };
 127
 128 // A class to perform all the relocations for an object file.
 129
 130 class Relocate_task : public Task
 131 {
 132  public:
 133   Relocate_task(const General_options& options, const Symbol_table* symtab,
 134                 const Layout* layout, Relobj* object, Output_file* of,
 135                 Task_token* input_sections_blocker,
 136                 Task_token* output_sections_blocker, Task_token* final_blocker)
 137     : options_(options), symtab_(symtab), layout_(layout), object_(object),
 138       of_(of), input_sections_blocker_(input_sections_blocker),
 139       output_sections_blocker_(output_sections_blocker),
 140       final_blocker_(final_blocker)
 141   { }
 142
 143   // The standard Task methods.
 144
 145   Is_runnable_type
 146   is_runnable(Workqueue*);
 147
 148   Task_locker*
 149   locks(Workqueue*);
 150
 151   void
 152   run(Workqueue*);
 153
 154  private:
 155   class Relocate_locker;
 156
 157   const General_options& options_;
 158   const Symbol_table* symtab_;
 159   const Layout* layout_;
 160   Relobj* object_;
 161   Output_file* of_;
 162   Task_token* input_sections_blocker_;
 163   Task_token* output_sections_blocker_;
 164   Task_token* final_blocker_;
 165 };
 166
 167 // Standard relocation routines which are used on many targets.  Here
 168 // SIZE and BIG_ENDIAN refer to the target, not the relocation type.
 169
 170 template<int size, bool big_endian>
 171 class Relocate_functions
 172 {
 173 private:
 174   // Do a simple relocation with the addend in the section contents.
 175   // VALSIZE is the size of the value.
 176   template<int valsize>
 177   static inline void
 178   rel(unsigned char* view,
 179       typename elfcpp::Swap<valsize, big_endian>::Valtype value)
 180   {
 181     typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
 182     Valtype* wv = reinterpret_cast<Valtype*>(view);
 183     Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv);
 184     elfcpp::Swap<valsize, big_endian>::writeval(wv, x + value);
 185   }
 186
 187   // Do a simple relocation using a Symbol_value with the addend in
 188   // the section contents.  VALSIZE is the size of the value to
 189   // relocate.
 190   template<int valsize>
 191   static inline void
 192   rel(unsigned char* view,
 193       const Sized_relobj<size, big_endian>* object,
 194       const Symbol_value<size>* psymval)
 195   {
 196     typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
 197     Valtype* wv = reinterpret_cast<Valtype*>(view);
 198     Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv);
 199     x = psymval->value(object, x);
 200     elfcpp::Swap<valsize, big_endian>::writeval(wv, x);
 201   }
 202
 203   // Do a simple relocation with the addend in the relocation.
 204   // VALSIZE is the size of the value.
 205   template<int valsize>
 206   static inline void
 207   rela(unsigned char* view,
 208        typename elfcpp::Swap<valsize, big_endian>::Valtype value,
 209        typename elfcpp::Swap<valsize, big_endian>::Valtype addend)
 210   {
 211     typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
 212     Valtype* wv = reinterpret_cast<Valtype*>(view);
 213     elfcpp::Swap<valsize, big_endian>::writeval(wv, value + addend);
 214   }
 215
 216   // Do a simple relocation using a symbol value with the addend in
 217   // the relocation.  VALSIZE is the size of the value.
 218   template<int valsize>
 219   static inline void
 220   rela(unsigned char* view,
 221        const Sized_relobj<size, big_endian>* object,
 222        const Symbol_value<size>* psymval,
 223        typename elfcpp::Swap<valsize, big_endian>::Valtype addend)
 224   {
 225     typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
 226     Valtype* wv = reinterpret_cast<Valtype*>(view);
 227     Valtype x = psymval->value(object, addend);
 228     elfcpp::Swap<valsize, big_endian>::writeval(wv, x);
 229   }
 230
 231   // Do a simple PC relative relocation with the addend in the section
 232   // contents.  VALSIZE is the size of the value.
 233   template<int valsize>
 234   static inline void
 235   pcrel(unsigned char* view,
 236         typename elfcpp::Swap<valsize, big_endian>::Valtype value,
 237         typename elfcpp::Elf_types<size>::Elf_Addr address)
 238   {
 239     typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
 240     Valtype* wv = reinterpret_cast<Valtype*>(view);
 241     Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv);
 242     elfcpp::Swap<valsize, big_endian>::writeval(wv, x + value - address);
 243   }
 244
 245   // Do a simple PC relative relocation with a Symbol_value with the
 246   // addend in the section contents.  VALSIZE is the size of the
 247   // value.
 248   template<int valsize>
 249   static inline void
 250   pcrel(unsigned char* view,
 251         const Sized_relobj<size, big_endian>* object,
 252         const Symbol_value<size>* psymval,
 253         typename elfcpp::Elf_types<size>::Elf_Addr address)
 254   {
 255     typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
 256     Valtype* wv = reinterpret_cast<Valtype*>(view);
 257     Valtype x = elfcpp::Swap<valsize, big_endian>::readval(wv);
 258     x = psymval->value(object, x);
 259     elfcpp::Swap<valsize, big_endian>::writeval(wv, x - address);
 260   }
 261
 262   // Do a simple PC relative relocation with the addend in the
 263   // relocation.  VALSIZE is the size of the value.
 264   template<int valsize>
 265   static inline void
 266   pcrela(unsigned char* view,
 267          typename elfcpp::Swap<valsize, big_endian>::Valtype value,
 268          typename elfcpp::Swap<valsize, big_endian>::Valtype addend,
 269          typename elfcpp::Elf_types<size>::Elf_Addr address)
 270   {
 271     typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
 272     Valtype* wv = reinterpret_cast<Valtype*>(view);
 273     elfcpp::Swap<valsize, big_endian>::writeval(wv, value + addend - address);
 274   }
 275
 276   // Do a simple PC relative relocation with a Symbol_value with the
 277   // addend in the relocation.  VALSIZE is the size of the value.
 278   template<int valsize>
 279   static inline void
 280   pcrela(unsigned char* view,
 281          const Sized_relobj<size, big_endian>* object,
 282          const Symbol_value<size>* psymval,
 283          typename elfcpp::Swap<valsize, big_endian>::Valtype addend,
 284          typename elfcpp::Elf_types<size>::Elf_Addr address)
 285   {
 286     typedef typename elfcpp::Swap<valsize, big_endian>::Valtype Valtype;
 287     Valtype* wv = reinterpret_cast<Valtype*>(view);
 288     Valtype x = psymval->value(object, addend);
 289     elfcpp::Swap<valsize, big_endian>::writeval(wv, x - address);
 290   }
 291
 292   typedef Relocate_functions<size, big_endian> This;
 293
 294 public:
 295   // Do a simple 8-bit REL relocation with the addend in the section
 296   // contents.
 297   static inline void
 298   rel8(unsigned char* view, unsigned char value)
 299   { This::template rel<8>(view, value); }
 300
 301   static inline void
 302   rel8(unsigned char* view,
 303        const Sized_relobj<size, big_endian>* object,
 304        const Symbol_value<size>* psymval)
 305   { This::template rel<8>(view, object, psymval); }
 306
 307   // Do an 8-bit RELA relocation with the addend in the relocation.
 308   static inline void
 309   rela8(unsigned char* view, unsigned char value, unsigned char addend)
 310   { This::template rela<8>(view, value, addend); }
 311
 312   static inline void
 313   rela8(unsigned char* view,
 314         const Sized_relobj<size, big_endian>* object,
 315         const Symbol_value<size>* psymval,
 316         unsigned char addend)
 317   { This::template rela<8>(view, object, psymval, addend); }
 318
 319   // Do a simple 8-bit PC relative relocation with the addend in the
 320   // section contents.
 321   static inline void
 322   pcrel8(unsigned char* view, unsigned char value,
 323          typename elfcpp::Elf_types<size>::Elf_Addr address)
 324   { This::template pcrel<8>(view, value, address); }
 325
 326   static inline void
 327   pcrel8(unsigned char* view,
 328          const Sized_relobj<size, big_endian>* object,
 329          const Symbol_value<size>* psymval,
 330          typename elfcpp::Elf_types<size>::Elf_Addr address)
 331   { This::template pcrel<8>(view, object, psymval, address); }
 332
 333   // Do a simple 8-bit PC relative RELA relocation with the addend in
 334   // the reloc.
 335   static inline void
 336   pcrela8(unsigned char* view, unsigned char value, unsigned char addend,
 337           typename elfcpp::Elf_types<size>::Elf_Addr address)
 338   { This::template pcrela<8>(view, value, addend, address); }
 339
 340   static inline void
 341   pcrela8(unsigned char* view,
 342           const Sized_relobj<size, big_endian>* object,
 343           const Symbol_value<size>* psymval,
 344           unsigned char addend,
 345           typename elfcpp::Elf_types<size>::Elf_Addr address)
 346   { This::template pcrela<8>(view, object, psymval, addend, address); }
 347
 348   // Do a simple 16-bit REL relocation with the addend in the section
 349   // contents.
 350   static inline void
 351   rel16(unsigned char* view, elfcpp::Elf_Half value)
 352   { This::template rel<16>(view, value); }
 353
 354   static inline void
 355   rel16(unsigned char* view,
 356         const Sized_relobj<size, big_endian>* object,
 357         const Symbol_value<size>* psymval)
 358   { This::template rel<16>(view, object, psymval); }
 359
 360   // Do an 16-bit RELA relocation with the addend in the relocation.
 361   static inline void
 362   rela16(unsigned char* view, elfcpp::Elf_Half value, elfcpp::Elf_Half addend)
 363   { This::template rela<16>(view, value, addend); }
 364
 365   static inline void
 366   rela16(unsigned char* view,
 367          const Sized_relobj<size, big_endian>* object,
 368          const Symbol_value<size>* psymval,
 369          elfcpp::Elf_Half addend)
 370   { This::template rela<16>(view, object, psymval, addend); }
 371
 372   // Do a simple 16-bit PC relative REL relocation with the addend in
 373   // the section contents.
 374   static inline void
 375   pcrel16(unsigned char* view, elfcpp::Elf_Half value,
 376           typename elfcpp::Elf_types<size>::Elf_Addr address)
 377   { This::template pcrel<16>(view, value, address); }
 378
 379   static inline void
 380   pcrel16(unsigned char* view,
 381           const Sized_relobj<size, big_endian>* object,
 382           const Symbol_value<size>* psymval,
 383           typename elfcpp::Elf_types<size>::Elf_Addr address)
 384   { This::template pcrel<16>(view, object, psymval, address); }
 385
 386   // Do a simple 16-bit PC relative RELA relocation with the addend in
 387   // the reloc.
 388   static inline void
 389   pcrela16(unsigned char* view, elfcpp::Elf_Half value,
 390            elfcpp::Elf_Half addend,
 391            typename elfcpp::Elf_types<size>::Elf_Addr address)
 392   { This::template pcrela<16>(view, value, addend, address); }
 393
 394   static inline void
 395   pcrela16(unsigned char* view,
 396            const Sized_relobj<size, big_endian>* object,
 397            const Symbol_value<size>* psymval,
 398            elfcpp::Elf_Half addend,
 399            typename elfcpp::Elf_types<size>::Elf_Addr address)
 400   { This::template pcrela<16>(view, object, psymval, addend, address); }
 401
 402   // Do a simple 32-bit REL relocation with the addend in the section
 403   // contents.
 404   static inline void
 405   rel32(unsigned char* view, elfcpp::Elf_Word value)
 406   { This::template rel<32>(view, value); }
 407
 408   static inline void
 409   rel32(unsigned char* view,
 410         const Sized_relobj<size, big_endian>* object,
 411         const Symbol_value<size>* psymval)
 412   { This::template rel<32>(view, object, psymval); }
 413
 414   // Do an 32-bit RELA relocation with the addend in the relocation.
 415   static inline void
 416   rela32(unsigned char* view, elfcpp::Elf_Word value, elfcpp::Elf_Word addend)
 417   { This::template rela<32>(view, value, addend); }
 418
 419   static inline void
 420   rela32(unsigned char* view,
 421          const Sized_relobj<size, big_endian>* object,
 422          const Symbol_value<size>* psymval,
 423          elfcpp::Elf_Word addend)
 424   { This::template rela<32>(view, object, psymval, addend); }
 425
 426   // Do a simple 32-bit PC relative REL relocation with the addend in
 427   // the section contents.
 428   static inline void
 429   pcrel32(unsigned char* view, elfcpp::Elf_Word value,
 430           typename elfcpp::Elf_types<size>::Elf_Addr address)
 431   { This::template pcrel<32>(view, value, address); }
 432
 433   static inline void
 434   pcrel32(unsigned char* view,
 435           const Sized_relobj<size, big_endian>* object,
 436           const Symbol_value<size>* psymval,
 437           typename elfcpp::Elf_types<size>::Elf_Addr address)
 438   { This::template pcrel<32>(view, object, psymval, address); }
 439
 440   // Do a simple 32-bit PC relative RELA relocation with the addend in
 441   // the relocation.
 442   static inline void
 443   pcrela32(unsigned char* view, elfcpp::Elf_Word value,
 444            elfcpp::Elf_Word addend,
 445            typename elfcpp::Elf_types<size>::Elf_Addr address)
 446   { This::template pcrela<32>(view, value, addend, address); }
 447
 448   static inline void
 449   pcrela32(unsigned char* view,
 450            const Sized_relobj<size, big_endian>* object,
 451            const Symbol_value<size>* psymval,
 452            elfcpp::Elf_Word addend,
 453            typename elfcpp::Elf_types<size>::Elf_Addr address)
 454   { This::template pcrela<32>(view, object, psymval, addend, address); }
 455
 456   // Do a simple 64-bit REL relocation with the addend in the section
 457   // contents.
 458   static inline void
 459   rel64(unsigned char* view, elfcpp::Elf_Xword value)
 460   { This::template rel<64>(view, value); }
 461
 462   static inline void
 463   rel64(unsigned char* view,
 464         const Sized_relobj<size, big_endian>* object,
 465         const Symbol_value<size>* psymval)
 466   { This::template rel<64>(view, object, psymval); }
 467
 468   // Do a 64-bit RELA relocation with the addend in the relocation.
 469   static inline void
 470   rela64(unsigned char* view, elfcpp::Elf_Xword value,
 471          elfcpp::Elf_Xword addend)
 472   { This::template rela<64>(view, value, addend); }
 473
 474   static inline void
 475   rela64(unsigned char* view,
 476          const Sized_relobj<size, big_endian>* object,
 477          const Symbol_value<size>* psymval,
 478          elfcpp::Elf_Xword addend)
 479   { This::template rela<64>(view, object, psymval, addend); }
 480
 481   // Do a simple 64-bit PC relative REL relocation with the addend in
 482   // the section contents.
 483   static inline void
 484   pcrel64(unsigned char* view, elfcpp::Elf_Xword value,
 485           typename elfcpp::Elf_types<size>::Elf_Addr address)
 486   { This::template pcrel<64>(view, value, address); }
 487
 488   static inline void
 489   pcrel64(unsigned char* view,
 490           const Sized_relobj<size, big_endian>* object,
 491           const Symbol_value<size>* psymval,
 492           typename elfcpp::Elf_types<size>::Elf_Addr address)
 493   { This::template pcrel<64>(view, object, psymval, address); }
 494
 495   // Do a simple 64-bit PC relative RELA relocation with the addend in
 496   // the relocation.
 497   static inline void
 498   pcrela64(unsigned char* view, elfcpp::Elf_Xword value,
 499            elfcpp::Elf_Xword addend,
 500            typename elfcpp::Elf_types<size>::Elf_Addr address)
 501   { This::template pcrela<64>(view, value, addend, address); }
 502
 503   static inline void
 504   pcrela64(unsigned char* view,
 505            const Sized_relobj<size, big_endian>* object,
 506            const Symbol_value<size>* psymval,
 507            elfcpp::Elf_Xword addend,
 508            typename elfcpp::Elf_types<size>::Elf_Addr address)
 509   { This::template pcrela<64>(view, object, psymval, addend, address); }
 510 };
 511
 512 // We try to avoid COPY relocations when possible.  A COPY relocation
 513 // may be required when an executable refers to a variable defined in
 514 // a shared library.  COPY relocations are problematic because they
 515 // tie the executable to the exact size of the variable in the shared
 516 // library.  We can avoid them if all the references to the variable
 517 // are in a writeable section.  In that case we can simply use dynamic
 518 // relocations.  However, when scanning relocs, we don't know when we
 519 // see the relocation whether we will be forced to use a COPY
 520 // relocation or not.  So we have to save the relocation during the
 521 // reloc scanning, and then emit it as a dynamic relocation if
 522 // necessary.  This class implements that.  It is used by the target
 523 // specific code.
 524
 525 template<int size, bool big_endian>
 526 class Copy_relocs
 527 {
 528  public:
 529   Copy_relocs()
 530     : entries_()
 531   { }
 532
 533   // Return whether we need a COPY reloc for a reloc against GSYM,
 534   // which is being applied to section SHNDX in OBJECT.
 535   static bool
 536   need_copy_reloc(const General_options*, Relobj* object, unsigned int shndx,
 537                   Sized_symbol<size>* gsym);
 538
 539   // Save a Rel against SYM for possible emission later.  SHNDX is the
 540   // index of the section to which the reloc is being applied.
 541   void
 542   save(Symbol* sym, Relobj*, unsigned int shndx,
 543        Output_section* output_section, const elfcpp::Rel<size, big_endian>&);
 544
 545   // Save a Rela against SYM for possible emission later.
 546   void
 547   save(Symbol* sym, Relobj*, unsigned int shndx,
 548        Output_section* output_section, const elfcpp::Rela<size, big_endian>&);
 549
 550   // Return whether there are any relocs to emit.  This also discards
 551   // entries which need not be emitted.
 552   bool
 553   any_to_emit();
 554
 555   // Emit relocs for each symbol which did not get a COPY reloc (i.e.,
 556   // is still defined in the dynamic object).
 557   template<int sh_type>
 558   void
 559   emit(Output_data_reloc<sh_type, true, size, big_endian>*);
 560
 561  private:
 562   typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
 563   typedef typename elfcpp::Elf_types<size>::Elf_Addr Addend;
 564
 565   // This POD class holds the entries we are saving.
 566   class Copy_reloc_entry
 567   {
 568    public:
 569     Copy_reloc_entry(Symbol* sym, unsigned int reloc_type,
 570                      Relobj* relobj, unsigned int shndx,
 571                      Output_section* output_section,
 572                      Address address, Addend addend)
 573       : sym_(sym), reloc_type_(reloc_type), relobj_(relobj),
 574         shndx_(shndx), output_section_(output_section),
 575         address_(address), addend_(addend)
 576     { }
 577
 578     // Return whether we should emit this reloc.  If we should not
 579     // emit, we clear it.
 580     bool
 581     should_emit();
 582
 583     // Emit this reloc.
 584
 585     void
 586     emit(Output_data_reloc<elfcpp::SHT_REL, true, size, big_endian>*);
 587
 588     void
 589     emit(Output_data_reloc<elfcpp::SHT_RELA, true, size, big_endian>*);
 590
 591    private:
 592     Symbol* sym_;
 593     unsigned int reloc_type_;
 594     Relobj* relobj_;
 595     unsigned int shndx_;
 596     Output_section* output_section_;
 597     Address address_;
 598     Addend addend_;
 599   };
 600
 601   // A list of relocs to be saved.
 602   typedef std::vector<Copy_reloc_entry> Copy_reloc_entries;
 603
 604   // The list of relocs we are saving.
 605   Copy_reloc_entries entries_;
 606 };
 607
 608 // Track relocations while reading a section.  This lets you ask for
 609 // the relocation at a certain offset, and see how relocs occur
 610 // between points of interest.
 611
 612 template<int size, bool big_endian>
 613 class Track_relocs
 614 {
 615  public:
 616   Track_relocs()
 617     : prelocs_(NULL), len_(0), pos_(0), reloc_size_(0)
 618   { }
 619
 620   // Initialize the Track_relocs object.  OBJECT is the object holding
 621   // the reloc section, RELOC_SHNDX is the section index of the reloc
 622   // section, and RELOC_TYPE is the type of the reloc section
 623   // (elfcpp::SHT_REL or elfcpp::SHT_RELA).  This returns false if
 624   // something went wrong.
 625   bool
 626   initialize(Object* object, unsigned int reloc_shndx,
 627              unsigned int reloc_type);
 628
 629   // Return the offset in the data section to which the next reloc
 630   // applies.  THis returns -1 if there is no next reloc.
 631   off_t
 632   next_offset() const;
 633
 634   // Return the symbol index of the next reloc.  This returns -1U if
 635   // there is no next reloc.
 636   unsigned int
 637   next_symndx() const;
 638
 639   // Advance to OFFSET within the data section, and return the number
 640   // of relocs which would be skipped.
 641   int
 642   advance(off_t offset);
 643
 644  private:
 645   // The contents of the input object's reloc section.
 646   const unsigned char* prelocs_;
 647   // The length of the reloc section.
 648   off_t len_;
 649   // Our current position in the reloc section.
 650   off_t pos_;
 651   // The size of the relocs in the section.
 652   int reloc_size_;
 653 };
 654
 655 } // End namespace gold.
 656
 657 #endif // !defined(GOLD_RELOC_H)