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_INCRMENTAL_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   // Return the type of input file.
 245   Incremental_input_type
 246   type() const
 247   { return this->do_type(); }
 248
 249   // Set the section offset of this input file entry.
 250   void
 251   set_offset(unsigned int offset)
 252   { this->offset_ = offset; }
 253
 254   // Set the section offset of the supplemental information for this entry.
 255   void
 256   set_info_offset(unsigned int info_offset)
 257   { this->info_offset_ = info_offset; }
 258
 259   // Get the section offset of this input file entry.
 260   unsigned int
 261   get_offset() const
 262   { return this->offset_; }
 263
 264   // Get the section offset of the supplemental information for this entry.
 265   unsigned int
 266   get_info_offset() const
 267   { return this->info_offset_; }
 268
 269   // Get the stringpool key for the input filename.
 270   Stringpool::Key
 271   get_filename_key() const
 272   { return this->filename_key_; }
 273
 274   // Get the modification time of the input file.
 275   const Timespec&
 276   get_mtime() const
 277   { return this->mtime_; }
 278
 279   // Return a pointer to the derived Incremental_script_entry object.
 280   // Return NULL for input entries that are not script files.
 281   Incremental_script_entry*
 282   script_entry()
 283   { return this->do_script_entry(); }
 284
 285   // Return a pointer to the derived Incremental_object_entry object.
 286   // Return NULL for input entries that are not object files.
 287   Incremental_object_entry*
 288   object_entry()
 289   { return this->do_object_entry(); }
 290
 291   // Return a pointer to the derived Incremental_archive_entry object.
 292   // Return NULL for input entries that are not archive files.
 293   Incremental_archive_entry*
 294   archive_entry()
 295   { return this->do_archive_entry(); }
 296
 297  protected:
 298   // Return the type of input file.
 299   virtual Incremental_input_type
 300   do_type() const = 0;
 301
 302   // Return a pointer to the derived Incremental_script_entry object.
 303   // Return NULL for input entries that are not script files.
 304   virtual Incremental_script_entry*
 305   do_script_entry()
 306   { return NULL; }
 307
 308   // Return a pointer to the derived Incremental_object_entry object.
 309   // Return NULL for input entries that are not object files.
 310   virtual Incremental_object_entry*
 311   do_object_entry()
 312   { return NULL; }
 313
 314   // Return a pointer to the derived Incremental_archive_entry object.
 315   // Return NULL for input entries that are not archive files.
 316   virtual Incremental_archive_entry*
 317   do_archive_entry()
 318   { return NULL; }
 319
 320  private:
 321   // Key of the filename string in the section stringtable.
 322   Stringpool::Key filename_key_;
 323
 324   // Offset of the entry in the output section.
 325   unsigned int offset_;
 326
 327   // Offset of the extra information in the output section.
 328   unsigned int info_offset_;
 329
 330   // Last modification time of the file.
 331   Timespec mtime_;
 332 };
 333
 334 // Class for recording input scripts.
 335
 336 class Incremental_script_entry : public Incremental_input_entry
 337 {
 338  public:
 339   Incremental_script_entry(Stringpool::Key filename_key, Script_info* script,
 340                            Timespec mtime)
 341     : Incremental_input_entry(filename_key, mtime), script_(script)
 342   { }
 343
 344  protected:
 345   virtual Incremental_input_type
 346   do_type() const
 347   { return INCREMENTAL_INPUT_SCRIPT; }
 348
 349   // Return a pointer to the derived Incremental_script_entry object.
 350   virtual Incremental_script_entry*
 351   do_script_entry()
 352   { return this; }
 353
 354  private:
 355   // Information about the script file.
 356   Script_info* script_;
 357 };
 358
 359 // Class for recording input object files.
 360
 361 class Incremental_object_entry : public Incremental_input_entry
 362 {
 363  public:
 364   Incremental_object_entry(Stringpool::Key filename_key, Object* obj,
 365                            Timespec mtime)
 366     : Incremental_input_entry(filename_key, mtime), obj_(obj),
 367       is_member_(false), sections_()
 368   {
 369     if (!obj_->is_dynamic())
 370       this->sections_.reserve(obj->shnum());
 371   }
 372
 373   // Get the object.
 374   Object*
 375   object() const
 376   { return this->obj_; }
 377
 378   // Record that this object is an archive member.
 379   void
 380   set_is_member()
 381   { this->is_member_ = true; }
 382
 383   // Return true if this object is an archive member.
 384   bool
 385   is_member() const
 386   { return this->is_member_; }
 387
 388   // Add an input section.
 389   void
 390   add_input_section(unsigned int shndx, Stringpool::Key name_key, off_t sh_size)
 391   {
 392     if (shndx >= this->sections_.size())
 393       this->sections_.resize(shndx + 1);
 394     this->sections_[shndx].name_key = name_key;
 395     this->sections_[shndx].sh_size = sh_size;
 396   }
 397
 398   // Return the number of input sections in this object.
 399   unsigned int
 400   get_input_section_count() const
 401   { return this->sections_.size(); }
 402
 403   // Return the stringpool key of the Nth input section.
 404   Stringpool::Key
 405   get_input_section_name_key(unsigned int n) const
 406   { return this->sections_[n].name_key; }
 407
 408   // Return the size of the Nth input section.
 409   off_t
 410   get_input_section_size(unsigned int n) const
 411   { return this->sections_[n].sh_size; }
 412
 413  protected:
 414   virtual Incremental_input_type
 415   do_type() const
 416   {
 417     return (this->is_member_
 418             ? INCREMENTAL_INPUT_ARCHIVE_MEMBER
 419             : (this->obj_->is_dynamic()
 420                ? INCREMENTAL_INPUT_SHARED_LIBRARY
 421                : INCREMENTAL_INPUT_OBJECT));
 422   }
 423
 424   // Return a pointer to the derived Incremental_object_entry object.
 425   virtual Incremental_object_entry*
 426   do_object_entry()
 427   { return this; }
 428
 429  private:
 430   // The object file itself.
 431   Object* obj_;
 432
 433   // Whether this object is an archive member.
 434   bool is_member_;
 435
 436   // Input sections.
 437   struct Input_section
 438   {
 439     Stringpool::Key name_key;
 440     off_t sh_size;
 441   };
 442   std::vector<Input_section> sections_;
 443 };
 444
 445 // Class for recording archive library input files.
 446
 447 class Incremental_archive_entry : public Incremental_input_entry
 448 {
 449  public:
 450   Incremental_archive_entry(Stringpool::Key filename_key, Archive*,
 451                             Timespec mtime)
 452     : Incremental_input_entry(filename_key, mtime), members_(), unused_syms_()
 453   { }
 454
 455   // Add a member object to the archive.
 456   void
 457   add_object(Incremental_object_entry* obj_entry)
 458   {
 459     this->members_.push_back(obj_entry);
 460     obj_entry->set_is_member();
 461   }
 462
 463   // Add an unused global symbol to the archive.
 464   void
 465   add_unused_global_symbol(Stringpool::Key symbol_key)
 466   { this->unused_syms_.push_back(symbol_key); }
 467
 468   // Return the number of member objects included in the link.
 469   unsigned int
 470   get_member_count()
 471   { return this->members_.size(); }
 472
 473   // Return the Nth member object.
 474   Incremental_object_entry*
 475   get_member(unsigned int n)
 476   { return this->members_[n]; }
 477
 478   // Return the number of unused global symbols in this archive.
 479   unsigned int
 480   get_unused_global_symbol_count()
 481   { return this->unused_syms_.size(); }
 482
 483   // Return the Nth unused global symbol.
 484   Stringpool::Key
 485   get_unused_global_symbol(unsigned int n)
 486   { return this->unused_syms_[n]; }
 487
 488  protected:
 489   virtual Incremental_input_type
 490   do_type() const
 491   { return INCREMENTAL_INPUT_ARCHIVE; }
 492
 493   // Return a pointer to the derived Incremental_archive_entry object.
 494   virtual Incremental_archive_entry*
 495   do_archive_entry()
 496   { return this; }
 497
 498  private:
 499   // Members of the archive that have been included in the link.
 500   std::vector<Incremental_object_entry*> members_;
 501
 502   // Unused global symbols from this archive.
 503   std::vector<Stringpool::Key> unused_syms_;
 504 };
 505
 506 // This class contains the information needed during an incremental
 507 // build about the inputs necessary to build the .gnu_incremental_inputs.
 508
 509 class Incremental_inputs
 510 {
 511  public:
 512   typedef std::vector<Incremental_input_entry*> Input_list;
 513
 514   Incremental_inputs()
 515     : inputs_(), command_line_(), command_line_key_(0),
 516       strtab_(new Stringpool()), current_object_(NULL),
 517       current_object_entry_(NULL), inputs_section_(NULL),
 518       symtab_section_(NULL), relocs_section_(NULL),
 519       reloc_count_(0)
 520   { }
 521
 522   ~Incremental_inputs() { delete this->strtab_; }
 523
 524   // Record the command line.
 525   void
 526   report_command_line(int argc, const char* const* argv);
 527
 528   // Record the initial info for archive file ARCHIVE.
 529   void
 530   report_archive_begin(Archive* arch);
 531
 532   // Record the final info for archive file ARCHIVE.
 533   void
 534   report_archive_end(Archive* arch);
 535
 536   // Record the info for object file OBJ.  If ARCH is not NULL,
 537   // attach the object file to the archive.
 538   void
 539   report_object(Object* obj, Archive* arch);
 540
 541   // Record an input section belonging to object file OBJ.
 542   void
 543   report_input_section(Object* obj, unsigned int shndx, const char* name,
 544                        off_t sh_size);
 545
 546   // Record the info for input script SCRIPT.
 547   void
 548   report_script(const std::string& filename, Script_info* script,
 549                 Timespec mtime);
 550
 551   // Return the running count of incremental relocations.
 552   unsigned int
 553   get_reloc_count() const
 554   { return this->reloc_count_; }
 555
 556   // Update the running count of incremental relocations.
 557   void
 558   set_reloc_count(unsigned int count)
 559   { this->reloc_count_ = count; }
 560
 561   // Prepare for layout.  Called from Layout::finalize.
 562   void
 563   finalize();
 564
 565   // Create the .gnu_incremental_inputs and related sections.
 566   void
 567   create_data_sections(Symbol_table* symtab);
 568
 569   // Return the .gnu_incremental_inputs section.
 570   Output_section_data*
 571   inputs_section() const
 572   { return this->inputs_section_; }
 573
 574   // Return the .gnu_incremental_symtab section.
 575   Output_data_space*
 576   symtab_section() const
 577   { return this->symtab_section_; }
 578
 579   // Return the .gnu_incremental_relocs section.
 580   Output_data_space*
 581   relocs_section() const
 582   { return this->relocs_section_; }
 583
 584   // Return the .gnu_incremental_got_plt section.
 585   Output_data_space*
 586   got_plt_section() const
 587   { return this->got_plt_section_; }
 588
 589   // Return the .gnu_incremental_strtab stringpool.
 590   Stringpool*
 591   get_stringpool() const
 592   { return this->strtab_; }
 593
 594   // Return the canonical form of the command line, as will be stored in
 595   // .gnu_incremental_strtab.
 596   const std::string&
 597   command_line() const
 598   { return this->command_line_; }
 599
 600   // Return the stringpool key of the command line.
 601   Stringpool::Key
 602   command_line_key() const
 603   { return this->command_line_key_; }
 604
 605   // Return the number of input files.
 606   int
 607   input_file_count() const
 608   { return this->inputs_.size(); }
 609
 610   // Return the input files.
 611   const Input_list&
 612   input_files() const
 613   { return this->inputs_; }
 614
 615   // Return the sh_entsize value for the .gnu_incremental_relocs section.
 616   unsigned int
 617   relocs_entsize() const;
 618
 619  private:
 620   // The list of input files.
 621   Input_list inputs_;
 622
 623   // Canonical form of the command line, as will be stored in
 624   // .gnu_incremental_strtab.
 625   std::string command_line_;
 626
 627   // The key of the command line string in the string pool.
 628   Stringpool::Key command_line_key_;
 629
 630   // The .gnu_incremental_strtab string pool associated with the
 631   // .gnu_incremental_inputs.
 632   Stringpool* strtab_;
 633
 634   // Keep track of the object currently being processed.
 635   Object* current_object_;
 636   Incremental_object_entry* current_object_entry_;
 637
 638   // The .gnu_incremental_inputs section.
 639   Output_section_data* inputs_section_;
 640
 641   // The .gnu_incremental_symtab section.
 642   Output_data_space* symtab_section_;
 643
 644   // The .gnu_incremental_relocs section.
 645   Output_data_space* relocs_section_;
 646
 647   // The .gnu_incremental_got_plt section.
 648   Output_data_space* got_plt_section_;
 649
 650   // Total count of incremental relocations.  Updated during Scan_relocs
 651   // phase at the completion of each object file.
 652   unsigned int reloc_count_;
 653 };
 654
 655 // Reader class for .gnu_incremental_inputs section.
 656
 657 template<int size, bool big_endian>
 658 class Incremental_inputs_reader
 659 {
 660  private:
 661   typedef elfcpp::Swap<size, big_endian> Swap;
 662   typedef elfcpp::Swap<16, big_endian> Swap16;
 663   typedef elfcpp::Swap<32, big_endian> Swap32;
 664   typedef elfcpp::Swap<64, big_endian> Swap64;
 665
 666  public:
 667   Incremental_inputs_reader(const unsigned char* p, elfcpp::Elf_strtab& strtab)
 668     : p_(p), strtab_(strtab)
 669   { this->input_file_count_ = Swap32::readval(this->p_ + 4); }
 670
 671   // Return the version number.
 672   unsigned int
 673   version() const
 674   { return Swap32::readval(this->p_); }
 675
 676   // Return the count of input file entries.
 677   unsigned int
 678   input_file_count() const
 679   { return this->input_file_count_; }
 680
 681   // Return the command line.
 682   const char*
 683   command_line() const
 684   {
 685     unsigned int offset = Swap32::readval(this->p_ + 8);
 686     return this->get_string(offset);
 687   }
 688
 689   // Reader class for an input file entry and its supplemental info.
 690   class Incremental_input_entry_reader
 691   {
 692    public:
 693     Incremental_input_entry_reader(const Incremental_inputs_reader* inputs,
 694                                    unsigned int offset)
 695       : inputs_(inputs), offset_(offset)
 696     {
 697       this->info_offset_ = Swap32::readval(inputs->p_ + offset + 4);
 698       int type = Swap16::readval(this->inputs_->p_ + offset + 20);
 699       this->type_ = static_cast<Incremental_input_type>(type);
 700     }
 701
 702     // Return the filename.
 703     const char*
 704     filename() const
 705     {
 706       unsigned int offset = Swap32::readval(this->inputs_->p_ + this->offset_);
 707       return this->inputs_->get_string(offset);
 708     }
 709
 710     // Return the timestamp.
 711     Timespec
 712     get_mtime() const
 713     {
 714       Timespec t;
 715       const unsigned char* p = this->inputs_->p_ + this->offset_ + 8;
 716       t.seconds = Swap64::readval(p);
 717       t.nanoseconds = Swap32::readval(p+8);
 718       return t;
 719     }
 720
 721     // Return the type of input file.
 722     Incremental_input_type
 723     type() const
 724     { return this->type_; }
 725
 726     // Return the input section count -- for objects only.
 727     unsigned int
 728     get_input_section_count() const
 729     {
 730       gold_assert(this->type_ == INCREMENTAL_INPUT_OBJECT
 731                   || this->type_ == INCREMENTAL_INPUT_ARCHIVE_MEMBER);
 732       return Swap32::readval(this->inputs_->p_ + this->info_offset_);
 733     }
 734
 735     // Return the offset of the supplemental info for symbol SYMNDX --
 736     // for objects only.
 737     unsigned int
 738     get_symbol_offset(unsigned int symndx) const
 739     {
 740       gold_assert(this->type_ == INCREMENTAL_INPUT_OBJECT
 741                   || this->type_ == INCREMENTAL_INPUT_ARCHIVE_MEMBER);
 742
 743       unsigned int section_count = this->get_input_section_count();
 744       return (this->info_offset_ + 8
 745               + section_count * input_section_entry_size
 746               + symndx * 16);
 747     }
 748
 749     // Return the global symbol count -- for objects & shared libraries only.
 750     unsigned int
 751     get_global_symbol_count() const
 752     {
 753       switch (this->type_)
 754         {
 755         case INCREMENTAL_INPUT_OBJECT:
 756         case INCREMENTAL_INPUT_ARCHIVE_MEMBER:
 757           return Swap32::readval(this->inputs_->p_ + this->info_offset_ + 4);
 758         case INCREMENTAL_INPUT_SHARED_LIBRARY:
 759           return Swap32::readval(this->inputs_->p_ + this->info_offset_);
 760         default:
 761           gold_unreachable();
 762         }
 763     }
 764
 765     // Return the member count -- for archives only.
 766     unsigned int
 767     get_member_count() const
 768     {
 769       gold_assert(this->type_ == INCREMENTAL_INPUT_ARCHIVE);
 770       return Swap32::readval(this->inputs_->p_ + this->info_offset_);
 771     }
 772
 773     // Return the unused symbol count -- for archives only.
 774     unsigned int
 775     get_unused_symbol_count() const
 776     {
 777       gold_assert(this->type_ == INCREMENTAL_INPUT_ARCHIVE);
 778       return Swap32::readval(this->inputs_->p_ + this->info_offset_ + 4);
 779     }
 780
 781     // Return the input file offset for archive member N -- for archives only.
 782     unsigned int
 783     get_member_offset(unsigned int n) const
 784     {
 785       gold_assert(this->type_ == INCREMENTAL_INPUT_ARCHIVE);
 786       return Swap32::readval(this->inputs_->p_ + this->info_offset_
 787                              + 8 + n * 4);
 788     }
 789
 790     // Return the Nth unused global symbol -- for archives only.
 791     const char*
 792     get_unused_symbol(unsigned int n) const
 793     {
 794       gold_assert(this->type_ == INCREMENTAL_INPUT_ARCHIVE);
 795       unsigned int member_count = this->get_member_count();
 796       unsigned int offset = Swap32::readval(this->inputs_->p_
 797                                             + this->info_offset_ + 8
 798                                             + member_count * 4
 799                                             + n * 4);
 800       return this->inputs_->get_string(offset);
 801     }
 802
 803     // Information about an input section.
 804     struct Input_section_info
 805     {
 806       const char* name;
 807       unsigned int output_shndx;
 808       off_t sh_offset;
 809       off_t sh_size;
 810     };
 811
 812     // Return info about the Nth input section -- for objects only.
 813     Input_section_info
 814     get_input_section(unsigned int n) const
 815     {
 816       Input_section_info info;
 817       const unsigned char* p = (this->inputs_->p_
 818                                 + this->info_offset_ + 8
 819                                 + n * input_section_entry_size);
 820       unsigned int name_offset = Swap32::readval(p);
 821       info.name = this->inputs_->get_string(name_offset);
 822       info.output_shndx = Swap32::readval(p + 4);
 823       info.sh_offset = Swap::readval(p + 8);
 824       info.sh_size = Swap::readval(p + 8 + size / 8);
 825       return info;
 826     }
 827
 828     // Information about a global symbol.
 829     struct Global_symbol_info
 830     {
 831       unsigned int output_symndx;
 832       unsigned int next_offset;
 833       unsigned int reloc_count;
 834       unsigned int reloc_offset;
 835     };
 836
 837     // Return info about the Nth global symbol -- for objects only.
 838     Global_symbol_info
 839     get_global_symbol_info(unsigned int n) const
 840     {
 841       Global_symbol_info info;
 842       unsigned int section_count = this->get_input_section_count();
 843       const unsigned char* p = (this->inputs_->p_
 844                                 + this->info_offset_ + 8
 845                                 + section_count * input_section_entry_size
 846                                 + n * 16);
 847       info.output_symndx = Swap32::readval(p);
 848       info.next_offset = Swap32::readval(p + 4);
 849       info.reloc_count = Swap::readval(p + 8);
 850       info.reloc_offset = Swap::readval(p + 12);
 851       return info;
 852     }
 853
 854    private:
 855     // Size of an input section entry.
 856     static const unsigned int input_section_entry_size = 8 + 2 * size / 8;
 857     // The reader instance for the containing section.
 858     const Incremental_inputs_reader* inputs_;
 859     // The type of input file.
 860     Incremental_input_type type_;
 861     // Section offset to the input file entry.
 862     unsigned int offset_;
 863     // Section offset to the supplemental info for the input file.
 864     unsigned int info_offset_;
 865   };
 866
 867   // Return a reader for the Nth input file entry.
 868   Incremental_input_entry_reader
 869   input_file(unsigned int n) const
 870   {
 871     gold_assert(n < this->input_file_count_);
 872     Incremental_input_entry_reader input(this, 16 + n * 24);
 873     return input;
 874   }
 875
 876  private:
 877   // Lookup a string in the ELF string table.
 878   const char* get_string(unsigned int offset) const
 879   {
 880     const char* s;
 881     if (this->strtab_.get_c_string(offset, &s))
 882       return s;
 883     return NULL;
 884   }
 885
 886   // Base address of the .gnu_incremental_inputs section.
 887   const unsigned char* p_;
 888   // The associated ELF string table.
 889   elfcpp::Elf_strtab strtab_;
 890   // The number of input file entries in this section.
 891   unsigned int input_file_count_;
 892 };
 893
 894 // Reader class for the .gnu_incremental_symtab section.
 895
 896 template<bool big_endian>
 897 class Incremental_symtab_reader
 898 {
 899  public:
 900   Incremental_symtab_reader(const unsigned char* p) : p_(p)
 901   { }
 902
 903   // Return the list head for symbol table entry N.
 904   unsigned int get_list_head(unsigned int n) const
 905   { return elfcpp::Swap<32, big_endian>::readval(this->p_ + 4 * n); }
 906
 907  private:
 908   // Base address of the .gnu_incremental_relocs section.
 909   const unsigned char* p_;
 910 };
 911
 912 // Reader class for the .gnu_incremental_relocs section.
 913
 914 template<int size, bool big_endian>
 915 class Incremental_relocs_reader
 916 {
 917  private:
 918   // Size of each field.
 919   static const unsigned int field_size = size / 8;
 920
 921  public:
 922   typedef typename elfcpp::Elf_types<size>::Elf_Addr Address;
 923   typedef typename elfcpp::Elf_types<size>::Elf_Swxword Addend;
 924
 925   // Size of each entry.
 926   static const unsigned int reloc_size = 8 + 2 * field_size;
 927
 928   Incremental_relocs_reader(const unsigned char* p) : p_(p)
 929   { }
 930
 931   // Return the relocation type for relocation entry at offset OFF.
 932   unsigned int
 933   get_r_type(unsigned int off) const
 934   {
 935     return elfcpp::Swap<32, big_endian>::readval(this->p_ + off);
 936   }
 937
 938   // Return the output section index for relocation entry at offset OFF.
 939   unsigned int
 940   get_r_shndx(unsigned int off) const
 941   {
 942     return elfcpp::Swap<32, big_endian>::readval(this->p_ + off + 4);
 943   }
 944
 945   // Return the output section offset for relocation entry at offset OFF.
 946   Address
 947   get_r_offset(unsigned int off) const
 948   {
 949     return elfcpp::Swap<size, big_endian>::readval(this->p_ + off + 8);
 950   }
 951
 952   // Return the addend for relocation entry at offset OFF.
 953   Addend
 954   get_r_addend(unsigned int off) const
 955   {
 956     return elfcpp::Swap<size, big_endian>::readval(this->p_ + off + 8
 957                                                    + this->field_size);
 958   }
 959
 960  private:
 961   // Base address of the .gnu_incremental_relocs section.
 962   const unsigned char* p_;
 963 };
 964
 965 // Reader class for the .gnu_incremental_got_plt section.
 966
 967 template<bool big_endian>
 968 class Incremental_got_plt_reader
 969 {
 970  public:
 971   Incremental_got_plt_reader(const unsigned char* p) : p_(p)
 972   {
 973     this->got_count_ = elfcpp::Swap<32, big_endian>::readval(p);
 974     this->got_desc_p_ = p + 8 + ((this->got_count_ + 3) & ~3);
 975     this->plt_desc_p_ = this->got_desc_p_ + this->got_count_ * 4;
 976   }
 977
 978   // Return the GOT entry count.
 979   unsigned int
 980   get_got_entry_count() const
 981   {
 982     return this->got_count_;
 983   }
 984
 985   // Return the PLT entry count.
 986   unsigned int
 987   get_plt_entry_count() const
 988   {
 989     return elfcpp::Swap<32, big_endian>::readval(this->p_ + 4);
 990   }
 991
 992   // Return the GOT type for GOT entry N.
 993   unsigned int
 994   get_got_type(unsigned int n)
 995   {
 996     return this->p_[8 + n];
 997   }
 998
 999   // Return the GOT descriptor for GOT entry N.
1000   unsigned int
1001   get_got_desc(unsigned int n)
1002   {
1003     return elfcpp::Swap<32, big_endian>::readval(this->got_desc_p_ + n * 4);
1004   }
1005
1006   // Return the PLT descriptor for PLT entry N.
1007   unsigned int
1008   get_plt_desc(unsigned int n)
1009   {
1010     return elfcpp::Swap<32, big_endian>::readval(this->plt_desc_p_ + n * 4);
1011   }
1012
1013  private:
1014   // Base address of the .gnu_incremental_got_plt section.
1015   const unsigned char* p_;
1016   // GOT entry count.
1017   unsigned int got_count_;
1018   // Base address of the GOT descriptor array.
1019   const unsigned char* got_desc_p_;
1020   // Base address of the PLT descriptor array.
1021   const unsigned char* plt_desc_p_;
1022 };
1023
1024 } // End namespace gold.
1025
1026 #endif // !defined(GOLD_INCREMENTAL_H)