gold/incremental.h

   1 // inremental.h -- incremental linking support for gold   -*- C++ -*-
   2
   3 // Copyright 2009, 2010 Free Software Foundation, Inc.
   4 // Written by Mikolaj Zalewski <mikolajz@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_INCREMENTAL_H
  24 #define GOLD_INCREMENTAL_H
  25
  26 #include <map>
  27 #include <vector>
  28
  29 #include "elfcpp_file.h"
  30 #include "stringpool.h"
  31 #include "workqueue.h"
  32 #include "fileread.h"
  33 #include "output.h"
  34
  35 namespace gold
  36 {
  37
  38 class Archive;
  39 class Input_argument;
  40 class Incremental_inputs_checker;
  41 class Incremental_script_entry;
  42 class Incremental_object_entry;
  43 class Incremental_archive_entry;
  44 class Incremental_inputs;
  45 class Object;
  46
  47 // Incremental input type as stored in .gnu_incremental_inputs.
  48
  49 enum Incremental_input_type
  50 {
  51   INCREMENTAL_INPUT_OBJECT = 1,
  52   INCREMENTAL_INPUT_ARCHIVE_MEMBER = 2,
  53   INCREMENTAL_INPUT_ARCHIVE = 3,
  54   INCREMENTAL_INPUT_SHARED_LIBRARY = 4,
  55   INCREMENTAL_INPUT_SCRIPT = 5
  56 };
  57
  58 // An object representing the ELF file we edit during an incremental build.
  59 // Similar to Object or Dynobj, but operates on Output_file and contains
  60 // method specific to file edition (TBD). This is the abstract parent class
  61 // implemented in Sized_incremental_binary<size, big_endian> for a specific
  62 // endianness and size.
  63
  64 class Incremental_binary
  65 {
  66  public:
  67   Incremental_binary(Output_file* output, Target* target)
  68     : output_(output), target_(target)
  69   { }
  70
  71   virtual
  72   ~Incremental_binary()
  73   { }
  74
  75   // Functions and types for the elfcpp::Elf_file interface.  This
  76   // permit us to use Incremental_binary as the File template parameter for
  77   // elfcpp::Elf_file.
  78
  79   // The View class is returned by view.  It must support a single
  80   // method, data().  This is trivial, because Output_file::get_output_view
  81   // does what we need.
  82   class View
  83   {
  84    public:
  85     View(const unsigned char* p)
  86       : p_(p)
  87     { }
  88
  89     const unsigned char*
  90     data() const
  91     { return this->p_; }
  92
  93    private:
  94     const unsigned char* p_;
  95   };
  96
  97   // Return a View.
  98   View
  99   view(off_t file_offset, section_size_type data_size)
 100   { return View(this->output_->get_input_view(file_offset, data_size)); }
 101
 102   // A location in the file.
 103   struct Location
 104   {
 105     off_t file_offset;
 106     off_t data_size;
 107
 108     Location(off_t fo, section_size_type ds)
 109       : file_offset(fo), data_size(ds)
 110     { }
 111
 112     Location()
 113       : file_offset(0), data_size(0)
 114     { }
 115   };
 116
 117   // Get a View given a Location.
 118   View
 119   view(Location loc)
 120   { return View(this->view(loc.file_offset, loc.data_size)); }
 121
 122   // Report an error.
 123   void
 124   error(const char* format, ...) const ATTRIBUTE_PRINTF_2;
 125
 126   // Find the .gnu_incremental_inputs and related sections.  It selects the
 127   // first section of type SHT_GNU_INCREMENTAL_INPUTS,
 128   // SHT_GNU_INCREMENTAL_SYMTAB, and SHT_GNU_INCREMENTAL_RELOCS.
 129   // Returns false if the sections are not found.
 130   bool
 131   find_incremental_inputs_sections(unsigned int* p_inputs_shndx,
 132                                    unsigned int* p_symtab_shndx,
 133                                    unsigned int* p_relocs_shndx,
 134                                    unsigned int* p_got_plt_shndx,
 135                                    unsigned int* p_strtab_shndx)
 136   {
 137     return do_find_incremental_inputs_sections(p_inputs_shndx, p_symtab_shndx,
 138                                                p_relocs_shndx, p_got_plt_shndx,
 139                                                p_strtab_shndx);
 140   }
 141
 142   // Check the .gnu_incremental_inputs section to see whether an incremental
 143   // build is possible.
 144   // TODO: on success, should report what files needs to be rebuilt.
 145   // INCREMENTAL_INPUTS is used to read the canonical form of the command line
 146   // and read the input arguments.  TODO: for items that don't need to be
 147   // rebuilt, we should also copy the incremental input information.
 148   virtual bool
 149   check_inputs(Incremental_inputs* incremental_inputs)
 150   { return do_check_inputs(incremental_inputs); }
 151
 152  protected:
 153   // Find incremental inputs section.
 154   virtual bool
 155   do_find_incremental_inputs_sections(unsigned int* p_inputs_shndx,
 156                                       unsigned int* p_symtab_shndx,
 157                                       unsigned int* p_relocs_shndx,
 158                                       unsigned int* p_got_plt_shndx,
 159                                       unsigned int* p_strtab_shndx) = 0;
 160
 161   // Check the .gnu_incremental_inputs section to see whether an incremental
 162   // build is possible.
 163   virtual bool
 164   do_check_inputs(Incremental_inputs* incremental_inputs) = 0;
 165
 166  private:
 167   // Edited output file object.
 168   Output_file* output_;
 169   // Target of the output file.
 170   Target* target_;
 171 };
 172
 173 template<int size, bool big_endian>
 174 class Sized_incremental_binary : public Incremental_binary
 175 {
 176  public:
 177   Sized_incremental_binary(Output_file* output,
 178                            const elfcpp::Ehdr<size, big_endian>& ehdr,
 179                            Target* target)
 180     : Incremental_binary(output, target), elf_file_(this, ehdr)
 181   { }
 182
 183  protected:
 184   virtual bool
 185   do_find_incremental_inputs_sections(unsigned int* p_inputs_shndx,
 186                                       unsigned int* p_symtab_shndx,
 187                                       unsigned int* p_relocs_shndx,
 188                                       unsigned int* p_got_plt_shndx,
 189                                       unsigned int* p_strtab_shndx);
 190
 191   virtual bool
 192   do_check_inputs(Incremental_inputs* incremental_inputs);
 193
 194  private:
 195   // Output as an ELF file.
 196   elfcpp::Elf_file<size, big_endian, Incremental_binary> elf_file_;
 197 };
 198
 199 // Create an Incremental_binary object for FILE. Returns NULL is this is not
 200 // possible, e.g. FILE is not an ELF file or has an unsupported target.
 201
 202 Incremental_binary*
 203 open_incremental_binary(Output_file* file);
 204
 205 // Code invoked early during an incremental link that checks what files need
 206 // to be relinked.
 207
 208 class Incremental_checker
 209 {
 210  public:
 211   // Check if the file named OUTPUT_NAME can be linked incrementally.
 212   // INCREMENTAL_INPUTS must have the canonical form of the command line
 213   // and input arguments filled - at this point of linking other fields are
 214   // probably not filled yet.  TODO: for inputs that don't need to be
 215   // rebuilt, this function should fill the incremental input information.
 216   Incremental_checker(const char* output_name,
 217                       Incremental_inputs* incremental_inputs)
 218     : output_name_(output_name), incremental_inputs_(incremental_inputs)
 219   { }
 220
 221   // Analyzes the output file to check if incremental linking is possible and
 222   // what files needs to be relinked.
 223   bool
 224   can_incrementally_link_output_file();
 225
 226  private:
 227   // Name of the output file to analyze.
 228   const char* output_name_;
 229
 230   // The Incremental_inputs object. At this stage of link, only the command
 231   // line and inputs are filled.
 232   Incremental_inputs* incremental_inputs_;
 233 };
 234
 235 // Base class for recording each input file.
 236
 237 class Incremental_input_entry
 238 {
 239  public:
 240   Incremental_input_entry(Stringpool::Key filename_key, Timespec mtime)
 241     : filename_key_(filename_key), offset_(0), info_offset_(0), mtime_(mtime)
 242   { }
 243
 244   virtual
 245   ~Incremental_input_entry()
 246   { }
 247
 248   // Return the type of input file.
 249   Incremental_input_type
 250   type() const
 251   { return this->do_type(); }
 252
 253   // Set the section offset of this input file entry.
 254   void
 255   set_offset(unsigned int offset)
 256   { this->offset_ = offset; }
 257
 258   // Set the section offset of the supplemental information for this entry.
 259   void
 260   set_info_offset(unsigned int info_offset)
 261   { this->info_offset_ = info_offset; }
 262
 263   // Get the section offset of this input file entry.
 264   unsigned int
 265   get_offset() const
 266   { return this->offset_; }
 267
 268   // Get the section offset of the supplemental information for this entry.
 269   unsigned int
 270   get_info_offset() const
 271   { return this->info_offset_; }
 272
 273   // Get the stringpool key for the input filename.
 274   Stringpool::Key
 275   get_filename_key() const
 276   { return this->filename_key_; }
 277
 278   // Get the modification time of the input file.
 279   const Timespec&
 280   get_mtime() const
 281   { return this->mtime_; }
 282
 283   // Return a pointer to the derived Incremental_script_entry object.
 284   // Return NULL for input entries that are not script files.
 285   Incremental_script_entry*
 286   script_entry()
 287   { return this->do_script_entry(); }
 288
 289   // Return a pointer to the derived Incremental_object_entry object.
 290   // Return NULL for input entries that are not object files.
 291   Incremental_object_entry*
 292   object_entry()
 293   { return this->do_object_entry(); }
 294
 295   // Return a pointer to the derived Incremental_archive_entry object.
 296   // Return NULL for input entries that are not archive files.
 297   Incremental_archive_entry*
 298   archive_entry()
 299   { return this->do_archive_entry(); }
 300
 301  protected:
 302   // Return the type of input file.
 303   virtual Incremental_input_type
 304   do_type() const = 0;
 305
 306   // Return a pointer to the derived Incremental_script_entry object.
 307   // Return NULL for input entries that are not script files.
 308   virtual Incremental_script_entry*
 309   do_script_entry()
 310   { return NULL; }
 311
 312   // Return a pointer to the derived Incremental_object_entry object.
 313   // Return NULL for input entries that are not object files.
 314   virtual Incremental_object_entry*
 315   do_object_entry()
 316   { return NULL; }
 317
 318   // Return a pointer to the derived Incremental_archive_entry object.
 319   // Return NULL for input entries that are not archive files.
 320   virtual Incremental_archive_entry*
 321   do_archive_entry()
 322   { return NULL; }
 323
 324  private:
 325   // Key of the filename string in the section stringtable.
 326   Stringpool::Key filename_key_;
 327
 328   // Offset of the entry in the output section.
 329   unsigned int offset_;
 330
 331   // Offset of the extra information in the output section.
 332   unsigned int info_offset_;
 333
 334   // Last modification time of the file.
 335   Timespec mtime_;
 336 };
 337
 338 // Class for recording input scripts.
 339
 340 class Incremental_script_entry : public Incremental_input_entry
 341 {
 342  public:
 343   Incremental_script_entry(Stringpool::Key filename_key, Script_info* script,
 344                            Timespec mtime)
 345     : Incremental_input_entry(filename_key, mtime), script_(script)
 346   { }
 347
 348  protected:
 349   virtual Incremental_input_type
 350   do_type() const
 351   { return INCREMENTAL_INPUT_SCRIPT; }
 352
 353   // Return a pointer to the derived Incremental_script_entry object.
 354   virtual Incremental_script_entry*
 355   do_script_entry()
 356   { return this; }
 357
 358  private:
 359   // Information about the script file.
 360   Script_info* script_;
 361 };
 362
 363 // Class for recording input object files.
 364
 365 class Incremental_object_entry : public Incremental_input_entry
 366 {
 367  public:
 368   Incremental_object_entry(Stringpool::Key filename_key, Object* obj,
 369                            Timespec mtime)
 370     : Incremental_input_entry(filename_key, mtime), obj_(obj),
 371       is_member_(false), sections_()
 372   {
 373     if (!obj_->is_dynamic())
 374       this->sections_.reserve(obj->shnum());
 375   }
 376
 377   // Get the object.
 378   Object*
 379   object() const
 380   { return this->obj_; }
 381
 382   // Record that this object is an archive member.
 383   void
 384   set_is_member()
 385   { this->is_member_ = true; }
 386
 387   // Return true if this object is an archive member.
 388   bool
 389   is_member() const
 390   { return this->is_member_; }
 391
 392   // Add an input section.
 393   void
 394   add_input_section(unsigned int shndx, Stringpool::Key name_key, off_t sh_size)
 395   {
 396     if (shndx >= this->sections_.size())
 397       this->sections_.resize(shndx + 1);
 398     this->sections_[shndx].name_key = name_key;
 399     this->sections_[shndx].sh_size = sh_size;
 400   }
 401
 402   // Return the number of input sections in this object.
 403   unsigned int
 404   get_input_section_count() const
 405   { return this->sections_.size(); }
 406
 407   // Return the stringpool key of the Nth input section.
 408   Stringpool::Key
 409   get_input_section_name_key(unsigned int n) const
 410   { return this->sections_[n].name_key; }
 411
 412   // Return the size of the Nth input section.
 413   off_t
 414   get_input_section_size(unsigned int n) const
 415   { return this->sections_[n].sh_size; }
 416
 417  protected:
 418   virtual Incremental_input_type
 419   do_type() const
 420   {
 421     return (this->is_member_
 422             ? INCREMENTAL_INPUT_ARCHIVE_MEMBER
 423             : (this->obj_->is_dynamic()
 424                ? INCREMENTAL_INPUT_SHARED_LIBRARY
 425                : INCREMENTAL_INPUT_OBJECT));
 426   }
 427
 428   // Return a pointer to the derived Incremental_object_entry object.
 429   virtual Incremental_object_entry*
 430   do_object_entry()
 431   { return this; }
 432
 433  private:
 434   // The object file itself.
 435   Object* obj_;
 436
 437   // Whether this object is an archive member.
 438   bool is_member_;
 439
 440   // Input sections.
 441   struct Input_section
 442   {
 443     Stringpool::Key name_key;
 444     off_t sh_size;
 445   };
 446   std::vector<Input_section> sections_;
 447 };
 448
 449 // Class for recording archive library input files.
 450
 451 class Incremental_archive_entry : public Incremental_input_entry
 452 {
 453  public:
 454   Incremental_archive_entry(Stringpool::Key filename_key, Archive*,
 455                             Timespec mtime)
 456     : Incremental_input_entry(filename_key, mtime), members_(), unused_syms_()
 457   { }
 458
 459   // Add a member object to the archive.
 460   void
 461   add_object(Incremental_object_entry* obj_entry)
 462   {
 463     this->members_.push_back(obj_entry);
 464     obj_entry->set_is_member();
 465   }
 466
 467   // Add an unused global symbol to the archive.
 468   void
 469   add_unused_global_symbol(Stringpool::Key symbol_key)
 470   { this->unused_syms_.push_back(symbol_key); }
 471
 472   // Return the number of member objects included in the link.
 473   unsigned int
 474   get_member_count()
 475   { return this->members_.size(); }
 476
 477   // Return the Nth member object.
 478   Incremental_object_entry*
 479   get_member(unsigned int n)
 480   { return this->members_[n]; }
 481
 482   // Return the number of unused global symbols in this archive.
 483   unsigned int
 484   get_unused_global_symbol_count()
 485   { return this->unused_syms_.size(); }
 486
 487   // Return the Nth unused global symbol.
 488   Stringpool::Key
 489   get_unused_global_symbol(unsigned int n)
 490   { return this->unused_syms_[n]; }
 491
 492  protected:
 493   virtual Incremental_input_type
 494   do_type() const
 495   { return INCREMENTAL_INPUT_ARCHIVE; }
 496
 497   // Return a pointer to the derived Incremental_archive_entry object.
 498   virtual Incremental_archive_entry*
 499   do_archive_entry()
 500   { return this; }
 501
 502  private:
 503   // Members of the archive that have been included in the link.
 504   std::vector<Incremental_object_entry*> members_;
 505
 506   // Unused global symbols from this archive.
 507   std::vector<Stringpool::Key> unused_syms_;
 508 };
 509
 510 // This class contains the information needed during an incremental
 511 // build about the inputs necessary to build the .gnu_incremental_inputs.
 512
 513 class Incremental_inputs
 514 {
 515  public:
 516   typedef std::vector<Incremental_input_entry*> Input_list;
 517
 518   Incremental_inputs()
 519     : inputs_(), command_line_(), command_line_key_(0),
 520       strtab_(new Stringpool()), current_object_(NULL),
 521       current_object_entry_(NULL), inputs_section_(NULL),
 522       symtab_section_(NULL), relocs_section_(NULL),
 523       reloc_count_(0)
 524   { }
 525
 526   ~Incremental_inputs() { delete this->strtab_; }
 527
 528   // Record the command line.
 529   void
 530   report_command_line(int argc, const char* const* argv);
 531
 532   // Record the initial info for archive file ARCHIVE.
 533   void
 534   report_archive_begin(Archive* arch);
 535
 536   // Record the final info for archive file ARCHIVE.
 537   void
 538   report_archive_end(Archive* arch);
 539
 540   // Record the info for object file OBJ.  If ARCH is not NULL,
 541   // attach the object file to the archive.
 542   void
 543   report_object(Object* obj, Archive* arch);
 544
 545   // Record an input section belonging to object file OBJ.
 546   void
 547   report_input_section(Object* obj, unsigned int shndx, const char* name,
 548                        off_t sh_size);
 549
 550   // Record the info for input script SCRIPT.
 551   void
 552   report_script(const std::string& filename, Script_info* script,
 553                 Timespec mtime);
 554
 555   // Return the running count of incremental relocations.
 556   unsigned int
 557   get_reloc_count() const
 558   { return this->reloc_count_; }
 559
 560   // Update the running count of incremental relocations.
 561   void
 562   set_reloc_count(unsigned int count)
 563   { this->reloc_count_ = count; }
 564
 565   // Prepare for layout.  Called from Layout::finalize.
 566   void
 567   finalize();
 568
 569   // Create the .gnu_incremental_inputs and related sections.
 570   void
 571   create_data_sections(Symbol_table* symtab);
 572
 573   // Return the .gnu_incremental_inputs section.
 574   Output_section_data*
 575   inputs_section() const
 576   { return this->inputs_section_; }
 577
 578   // Return the .gnu_incremental_symtab section.
 579   Output_data_space*
 580   symtab_section() const
 581   { return this->symtab_section_; }
 582
 583   // Return the .gnu_incremental_relocs section.
 584   Output_data_space*
 585   relocs_section() const
 586   { return this->relocs_section_; }
 587
 588   // Return the .gnu_incremental_got_plt section.
 589   Output_data_space*
 590   got_plt_section() const
 591   { return this->got_plt_section_; }
 592
 593   // Return the .gnu_incremental_strtab stringpool.
 594   Stringpool*
 595   get_stringpool() const
 596   { return this->strtab_; }
 597
 598   // Return the canonical form of the command line, as will be stored in
 599   // .gnu_incremental_strtab.
 600   const std::string&
 601   command_line() const
 602   { return this->command_line_; }
 603
 604   // Return the stringpool key of the command line.
 605   Stringpool::Key
 606   command_line_key() const
 607   { return this->command_line_key_; }
 608
 609   // Return the number of input files.
 610   int
 611   input_file_count() const
 612   { return this->inputs_.size(); }
 613
 614   // Return the input files.
 615   const Input_list&
 616   input_files() const
 617   { return this->inputs_; }
 618
 619   // Return the sh_entsize value for the .gnu_incremental_relocs section.
 620   unsigned int
 621   relocs_entsize() const;
 622
 623  private:
 624   // The list of input files.
 625   Input_list inputs_;
 626
 627   // Canonical form of the command line, as will be stored in
 628   // .gnu_incremental_strtab.
 629   std::string command_line_;
 630
 631   // The key of the command line string in the string pool.
 632   Stringpool::Key command_line_key_;
 633
 634   // The .gnu_incremental_strtab string pool associated with the
 635   // .gnu_incremental_inputs.
 636   Stringpool* strtab_;
 637
 638   // Keep track of the object currently being processed.
 639   Object* current_object_;
 640   Incremental_object_entry* current_object_entry_;
 641
 642   // The .gnu_incremental_inputs section.
 643   Output_section_data* inputs_section_;
 644
 645   // The .gnu_incremental_symtab section.
 646   Output_data_space* symtab_section_;
 647
 648   // The .gnu_incremental_relocs section.
 649   Output_data_space* relocs_section_;
 650
 651   // The .gnu_incremental_got_plt section.
 652   Output_data_space* got_plt_section_;
 653
 654   // Total count of incremental relocations.  Updated during Scan_relocs
 655   // phase at the completion of each object file.
 656   unsigned int reloc_count_;
 657 };
 658
 659 // Reader class for .gnu_incremental_inputs section.
 660
 661 template<int size, bool big_endian>
 662 class Incremental_inputs_reader
 663 {
 664  private:
 665   typedef elfcpp::Swap<size, big_endian> Swap;
 666   typedef elfcpp::Swap<16, big_endian> Swap16;
 667   typedef elfcpp::Swap<32, big_endian> Swap32;
 668   typedef elfcpp::Swap<64, big_endian> Swap64;
 669
 670  public:
 671   Incremental_inputs_reader(const unsigned char* p, elfcpp::Elf_strtab& strtab)
 672     : p_(p), strtab_(strtab)
 673   { this->input_file_count_ = Swap32::readval(this->p_ + 4); }
 674
 675   // Return the version number.
 676   unsigned int
 677   version() const
 678   { return Swap32::readval(this->p_); }
 679
 680   // Return the count of input file entries.
 681   unsigned int
 682   input_file_count() const
 683   { return this->input_file_count_; }
 684
 685   // Return the command line.
 686   const char*
 687   command_line() const
 688   {
 689     unsigned int offset = Swap32::readval(this->p_ + 8);
 690     return this->get_string(offset);
 691   }
 692
 693   // Reader class for an input file entry and its supplemental info.
 694   class Incremental_input_entry_reader
 695   {
 696    public:
 697     Incremental_input_entry_reader(const Incremental_inputs_reader* inputs,
 698                                    unsigned int offset)
 699       : inputs_(inputs), offset_(offset)
 700     {
 701       this->info_offset_ = Swap32::readval(inputs->p_ + offset + 4);
 702       int type = Swap16::readval(this->inputs_->p_ + offset + 20);
 703       this->type_ = static_cast<Incremental_input_type>(type);
 704     }
 705
 706     // Return the filename.
 707     const char*
 708     filename() const
 709     {
 710       unsigned int offset = Swap32::readval(this->inputs_->p_ + this->offset_);
 711       return this->inputs_->get_string(offset);
 712     }
 713
 714     // Return the timestamp.
 715     Timespec
 716     get_mtime() const
 717     {
 718       Timespec t;
 719       const unsigned char* p = this->inputs_->p_ + this->offset_ + 8;
 720       t.seconds = Swap64::readval(p);
 721       t.nanoseconds = Swap32::readval(p+8);
 722       return t;
 723     }
 724
 725     // Return the type of input file.
 726     Incremental_input_type
 727     type() const
 728     { return this->type_; }
 729
 730     // Return the input section count -- for objects only.
 731     unsigned int
 732     get_input_section_count() const
 733     {
 734       gold_assert(this->type_ == INCREMENTAL_INPUT_OBJECT
 735                   || this->type_ == INCREMENTAL_INPUT_ARCHIVE_MEMBER);
 736       return Swap32::readval(this->inputs_->p_ + this->info_offset_);
 737     }
 738
 739     // Return the offset of the supplemental info for symbol SYMNDX --
 740     // for objects only.
 741     unsigned int
 742     get_symbol_offset(unsigned int symndx) const
 743     {
 744       gold_assert(this->type_ == INCREMENTAL_INPUT_OBJECT
 745                   || this->type_ == INCREMENTAL_INPUT_ARCHIVE_MEMBER);
 746
 747       unsigned int section_count = this->get_input_section_count();
 748       return (this->info_offset_ + 8
 749               + section_count * input_section_entry_size
 750               + symndx * 16);
 751     }
 752
 753     // Return the global symbol count -- for objects & shared libraries only.
 754     unsigned int
 755     get_global_symbol_count() const
 756     {
 757       switch (this->type_)
 758         {
 759         case INCREMENTAL_INPUT_OBJECT:
 760         case INCREMENTAL_INPUT_ARCHIVE_MEMBER:
 761           return Swap32::readval(this->inputs_->p_ + this->info_offset_ + 4);
 762         case INCREMENTAL_INPUT_SHARED_LIBRARY:
 763           return Swap32::readval(this->inputs_->p_ + this->info_offset_);
 764         default:
 765           gold_unreachable();
 766         }
 767     }
 768
 769     // Return the member count -- for archives only.
 770     unsigned int
 771     get_member_count() const
 772     {
 773       gold_assert(this->type_ == INCREMENTAL_INPUT_ARCHIVE);
 774       return Swap32::readval(this->inputs_->p_ + this->info_offset_);
 775     }
 776
 777     // Return the unused symbol count -- for archives only.
 778     unsigned int
 779     get_unused_symbol_count() const
 780     {
 781       gold_assert(this->type_ == INCREMENTAL_INPUT_ARCHIVE);
 782       return Swap32::readval(this->inputs_->p_ + this->info_offset_ + 4);
 783     }
 784
 785     // Return the input file offset for archive member N -- for archives only.
 786     unsigned int
 787     get_member_offset(unsigned int n) const
 788     {
 789       gold_assert(this->type_ == INCREMENTAL_INPUT_ARCHIVE);
 790       return Swap32::readval(this->inputs_->p_ + this->info_offset_
 791                              + 8 + n * 4);
 792     }
 793
 794     // Return the Nth unused global symbol -- for archives only.
 795     const char*
 796     get_unused_symbol(unsigned int n) const
 797     {
 798       gold_assert(this->type_ == INCREMENTAL_INPUT_ARCHIVE);
 799       unsigned int member_count = this->get_member_count();
 800       unsigned int offset = Swap32::readval(this->inputs_->p_
 801                                             + this->info_offset_ + 8
 802                                             + member_count * 4
 803                                             + n * 4);
 804       return this->inputs_->get_string(offset);
 805     }
 806
 807     // Information about an input section.
 808     struct Input_section_info
 809     {
 810       const char* name;
 811       unsigned int output_shndx;
 812       off_t sh_offset;
 813       off_t sh_size;
 814     };
 815
 816     // Return info about the Nth input section -- for objects only.
 817     Input_section_info
 818     get_input_section(unsigned int n) const
 819     {
 820       Input_section_info info;
 821       const unsigned char* p = (this->inputs_->p_
 822                                 + this->info_offset_ + 8
 823                                 + n * input_section_entry_size);
 824       unsigned int name_offset = Swap32::readval(p);
 825       info.name = this->inputs_->get_string(name_offset);
 826       info.output_shndx = Swap32::readval(p + 4);
 827       info.sh_offset = Swap::readval(p + 8);
 828       info.sh_size = Swap::readval(p + 8 + size / 8);
 829       return info;
 830     }
 831
 832     // Information about a global symbol.
 833     struct Global_symbol_info
 834     {
 835       unsigned int output_symndx;
 836       unsigned int next_offset;
 837       unsigned int reloc_count;
 838       unsigned int reloc_offset;
 839     };
 840
 841     // Return info about the Nth global symbol -- for objects only.
 842     Global_symbol_info
 843     get_global_symbol_info(unsigned int n) const
 844     {
 845       Global_symbol_info info;
 846       unsigned int section_count = this->get_input_section_count();
 847       const unsigned char* p = (this->inputs_->p_
 848                                 + this->info_offset_ + 8
 849                                 + section_count * input_section_entry_size
 850                                 + n * 16);
 851       info.output_symndx = Swap32::readval(p);
 852       info.next_offset = Swap32::readval(p + 4);
 853       info.reloc_count = Swap::readval(p + 8);
 854       info.reloc_offset = Swap::readval(p + 12);
 855       return info;
 856     }
 857
 858    private:
 859     // Size of an input section entry.
 860     static const unsigned int input_section_entry_size = 8 + 2 * size / 8;
 861     // The reader instance for the containing section.
 862     const Incremental_inputs_reader* inputs_;
 863     // The type of input file.
 864     Incremental_input_type type_;
 865     // Section offset to the input file entry.
 866     unsigned int offset_;
 867     // Section offset to the supplemental info for the input file.
 868     unsigned int info_offset_;
 869   };
 870
 871   // Return a reader for the Nth input file entry.
 872   Incremental_input_entry_reader
 873   input_file(unsigned int n) const
 874   {
 875     gold_assert(n < this->input_file_count_);
 876     Incremental_input_entry_reader input(this, 16 + n * 24);
 877     return input;
 878   }
 879
 880  private:
 881   // Lookup a string in the ELF string table.
 882   const char* get_string(unsigned int offset) const
 883   {
 884     const char* s;
 885     if (this->strtab_.get_c_string(offset, &s))
 886       return s;
 887     return NULL;
 888   }
 889
 890   // Base address of the .gnu_incremental_inputs section.
 891   const unsigned char* p_;
 892   // The associated ELF string table.
 893   elfcpp::Elf_strtab strtab_;
 894   // The number of input file entries in this section.
 895   unsigned int input_file_count_;
 896 };
 897
 898 // Reader class for the .gnu_incremental_symtab section.
 899
 900 template<bool big_endian>
 901 class Incremental_symtab_reader
 902 {
 903  public:
 904   Incremental_symtab_reader(const unsigned char* p) : p_(p)
 905   { }
 906
 907   // Return the list head for symbol table entry N.
 908   unsigned int get_list_head(unsigned int n) const
 909   { return elfcpp::Swap<32, big_endian>::readval(this->p_ + 4 * n); }
 910
 911  private:
 912   // Base address of the .gnu_incremental_relocs section.
 913   const unsigned char* p_;
 914 };
 915
 916 // Reader class for the .gnu_incremental_relocs section.
 917
 918 template<int size, bool big_endian>
 919 class Incremental_relocs_reader
 920 {
 921  private:
 922   // Size of each field.
 923   static const unsigned int field_size = size / 8;
 924
 925  public:
 926   typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
 927   typedef typename elfcpp::Elf_types<size>::Elf_Swxword Addend;
 928
 929   // Size of each entry.
 930   static const unsigned int reloc_size = 8 + 2 * field_size;
 931
 932   Incremental_relocs_reader(const unsigned char* p) : p_(p)
 933   { }
 934
 935   // Return the relocation type for relocation entry at offset OFF.
 936   unsigned int
 937   get_r_type(unsigned int off) const
 938   {
 939     return elfcpp::Swap<32, big_endian>::readval(this->p_ + off);
 940   }
 941
 942   // Return the output section index for relocation entry at offset OFF.
 943   unsigned int
 944   get_r_shndx(unsigned int off) const
 945   {
 946     return elfcpp::Swap<32, big_endian>::readval(this->p_ + off + 4);
 947   }
 948
 949   // Return the output section offset for relocation entry at offset OFF.
 950   Address
 951   get_r_offset(unsigned int off) const
 952   {
 953     return elfcpp::Swap<size, big_endian>::readval(this->p_ + off + 8);
 954   }
 955
 956   // Return the addend for relocation entry at offset OFF.
 957   Addend
 958   get_r_addend(unsigned int off) const
 959   {
 960     return elfcpp::Swap<size, big_endian>::readval(this->p_ + off + 8
 961                                                    + this->field_size);
 962   }
 963
 964  private:
 965   // Base address of the .gnu_incremental_relocs section.
 966   const unsigned char* p_;
 967 };
 968
 969 // Reader class for the .gnu_incremental_got_plt section.
 970
 971 template<bool big_endian>
 972 class Incremental_got_plt_reader
 973 {
 974  public:
 975   Incremental_got_plt_reader(const unsigned char* p) : p_(p)
 976   {
 977     this->got_count_ = elfcpp::Swap<32, big_endian>::readval(p);
 978     this->got_desc_p_ = p + 8 + ((this->got_count_ + 3) & ~3);
 979     this->plt_desc_p_ = this->got_desc_p_ + this->got_count_ * 4;
 980   }
 981
 982   // Return the GOT entry count.
 983   unsigned int
 984   get_got_entry_count() const
 985   {
 986     return this->got_count_;
 987   }
 988
 989   // Return the PLT entry count.
 990   unsigned int
 991   get_plt_entry_count() const
 992   {
 993     return elfcpp::Swap<32, big_endian>::readval(this->p_ + 4);
 994   }
 995
 996   // Return the GOT type for GOT entry N.
 997   unsigned int
 998   get_got_type(unsigned int n)
 999   {
1000     return this->p_[8 + n];
1001   }
1002
1003   // Return the GOT descriptor for GOT entry N.
1004   unsigned int
1005   get_got_desc(unsigned int n)
1006   {
1007     return elfcpp::Swap<32, big_endian>::readval(this->got_desc_p_ + n * 4);
1008   }
1009
1010   // Return the PLT descriptor for PLT entry N.
1011   unsigned int
1012   get_plt_desc(unsigned int n)
1013   {
1014     return elfcpp::Swap<32, big_endian>::readval(this->plt_desc_p_ + n * 4);
1015   }
1016
1017  private:
1018   // Base address of the .gnu_incremental_got_plt section.
1019   const unsigned char* p_;
1020   // GOT entry count.
1021   unsigned int got_count_;
1022   // Base address of the GOT descriptor array.
1023   const unsigned char* got_desc_p_;
1024   // Base address of the PLT descriptor array.
1025   const unsigned char* plt_desc_p_;
1026 };
1027
1028 } // End namespace gold.
1029
1030 #endif // !defined(GOLD_INCREMENTAL_H)