gold/dynobj.h

   1 // dynobj.h -- dynamic object support for gold   -*- C++ -*-
   2
   3 // Copyright 2006, 2007, 2008 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_DYNOBJ_H
  24 #define GOLD_DYNOBJ_H
  25
  26 #include <vector>
  27
  28 #include "stringpool.h"
  29 #include "object.h"
  30
  31 namespace gold
  32 {
  33
  34 class Version_script_info;
  35
  36 // A dynamic object (ET_DYN).  This is an abstract base class itself.
  37 // The implementations is the template class Sized_dynobj.
  38
  39 class Dynobj : public Object
  40 {
  41  public:
  42   // We keep a list of all the DT_NEEDED entries we find.
  43   typedef std::vector<std::string> Needed;
  44
  45   Dynobj(const std::string& name, Input_file* input_file, off_t offset = 0);
  46
  47   // Return the name to use in a DT_NEEDED entry for this object.
  48   const char*
  49   soname() const
  50   { return this->soname_.c_str(); }
  51
  52   // Return the list of DT_NEEDED strings.
  53   const Needed&
  54   needed() const
  55   { return this->needed_; }
  56
  57   // Return whether this dynamic object has any DT_NEEDED entries
  58   // which were not seen during the link.
  59   bool
  60   has_unknown_needed_entries() const
  61   {
  62     gold_assert(this->unknown_needed_ != UNKNOWN_NEEDED_UNSET);
  63     return this->unknown_needed_ == UNKNOWN_NEEDED_TRUE;
  64   }
  65
  66   // Set whether this dynamic object has any DT_NEEDED entries which
  67   // were not seen during the link.
  68   void
  69   set_has_unknown_needed_entries(bool set)
  70   {
  71     gold_assert(this->unknown_needed_ == UNKNOWN_NEEDED_UNSET);
  72     this->unknown_needed_ = set ? UNKNOWN_NEEDED_TRUE : UNKNOWN_NEEDED_FALSE;
  73   }
  74
  75   // Compute the ELF hash code for a string.
  76   static uint32_t
  77   elf_hash(const char*);
  78
  79   // Create a standard ELF hash table, setting *PPHASH and *PHASHLEN.
  80   // DYNSYMS is the global dynamic symbols.  LOCAL_DYNSYM_COUNT is the
  81   // number of local dynamic symbols, which is the index of the first
  82   // dynamic gobal symbol.
  83   static void
  84   create_elf_hash_table(const std::vector<Symbol*>& dynsyms,
  85                         unsigned int local_dynsym_count,
  86                         unsigned char** pphash,
  87                         unsigned int* phashlen);
  88
  89   // Create a GNU hash table, setting *PPHASH and *PHASHLEN.  DYNSYMS
  90   // is the global dynamic symbols.  LOCAL_DYNSYM_COUNT is the number
  91   // of local dynamic symbols, which is the index of the first dynamic
  92   // gobal symbol.
  93   static void
  94   create_gnu_hash_table(const std::vector<Symbol*>& dynsyms,
  95                         unsigned int local_dynsym_count,
  96                         unsigned char** pphash, unsigned int* phashlen);
  97
  98  protected:
  99   // Set the DT_SONAME string.
 100   void
 101   set_soname_string(const char* s)
 102   { this->soname_.assign(s); }
 103
 104   // Add an entry to the list of DT_NEEDED strings.
 105   void
 106   add_needed(const char* s)
 107   { this->needed_.push_back(std::string(s)); }
 108
 109  private:
 110   // Compute the GNU hash code for a string.
 111   static uint32_t
 112   gnu_hash(const char*);
 113
 114   // Compute the number of hash buckets to use.
 115   static unsigned int
 116   compute_bucket_count(const std::vector<uint32_t>& hashcodes,
 117                        bool for_gnu_hash_table);
 118
 119   // Sized version of create_elf_hash_table.
 120   template<bool big_endian>
 121   static void
 122   sized_create_elf_hash_table(const std::vector<uint32_t>& bucket,
 123                               const std::vector<uint32_t>& chain,
 124                               unsigned char* phash,
 125                               unsigned int hashlen);
 126
 127   // Sized version of create_gnu_hash_table.
 128   template<int size, bool big_endian>
 129   static void
 130   sized_create_gnu_hash_table(const std::vector<Symbol*>& hashed_dynsyms,
 131                               const std::vector<uint32_t>& dynsym_hashvals,
 132                               unsigned int unhashed_dynsym_count,
 133                               unsigned char** pphash,
 134                               unsigned int* phashlen);
 135
 136   // Values for the has_unknown_needed_entries_ field.
 137   enum Unknown_needed
 138   {
 139     UNKNOWN_NEEDED_UNSET,
 140     UNKNOWN_NEEDED_TRUE,
 141     UNKNOWN_NEEDED_FALSE
 142   };
 143
 144   // The DT_SONAME name, if any.
 145   std::string soname_;
 146   // The list of DT_NEEDED entries.
 147   Needed needed_;
 148   // Whether this dynamic object has any DT_NEEDED entries not seen
 149   // during the link.
 150   Unknown_needed unknown_needed_;
 151 };
 152
 153 // A dynamic object, size and endian specific version.
 154
 155 template<int size, bool big_endian>
 156 class Sized_dynobj : public Dynobj
 157 {
 158  public:
 159   Sized_dynobj(const std::string& name, Input_file* input_file, off_t offset,
 160                const typename elfcpp::Ehdr<size, big_endian>&);
 161
 162   // Set up the object file based on the ELF header.
 163   void
 164   setup(const typename elfcpp::Ehdr<size, big_endian>&);
 165
 166   // Read the symbols.
 167   void
 168   do_read_symbols(Read_symbols_data*);
 169
 170   // Lay out the input sections.
 171   void
 172   do_layout(Symbol_table*, Layout*, Read_symbols_data*);
 173
 174   // Add the symbols to the symbol table.
 175   void
 176   do_add_symbols(Symbol_table*, Read_symbols_data*);
 177
 178   // Get the size of a section.
 179   uint64_t
 180   do_section_size(unsigned int shndx)
 181   { return this->elf_file_.section_size(shndx); }
 182
 183   // Get the name of a section.
 184   std::string
 185   do_section_name(unsigned int shndx)
 186   { return this->elf_file_.section_name(shndx); }
 187
 188   // Return a view of the contents of a section.  Set *PLEN to the
 189   // size.
 190   Object::Location
 191   do_section_contents(unsigned int shndx)
 192   { return this->elf_file_.section_contents(shndx); }
 193
 194   // Return section flags.
 195   uint64_t
 196   do_section_flags(unsigned int shndx)
 197   { return this->elf_file_.section_flags(shndx); }
 198
 199   // Return section address.
 200   uint64_t
 201   do_section_address(unsigned int shndx)
 202   { return this->elf_file_.section_addr(shndx); }
 203
 204   // Return section type.
 205   unsigned int
 206   do_section_type(unsigned int shndx)
 207   { return this->elf_file_.section_type(shndx); }
 208
 209   // Return the section link field.
 210   unsigned int
 211   do_section_link(unsigned int shndx)
 212   { return this->elf_file_.section_link(shndx); }
 213
 214   // Return the section link field.
 215   unsigned int
 216   do_section_info(unsigned int shndx)
 217   { return this->elf_file_.section_info(shndx); }
 218
 219   // Return the section alignment.
 220   uint64_t
 221   do_section_addralign(unsigned int shndx)
 222   { return this->elf_file_.section_addralign(shndx); }
 223
 224   // Return the Xindex structure to use.
 225   Xindex*
 226   do_initialize_xindex();
 227
 228  private:
 229   // For convenience.
 230   typedef Sized_dynobj<size, big_endian> This;
 231   static const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
 232   static const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
 233   static const int dyn_size = elfcpp::Elf_sizes<size>::dyn_size;
 234   typedef elfcpp::Shdr<size, big_endian> Shdr;
 235   typedef elfcpp::Dyn<size, big_endian> Dyn;
 236
 237   // Adjust a section index if necessary.
 238   unsigned int
 239   adjust_shndx(unsigned int shndx)
 240   {
 241     if (shndx >= elfcpp::SHN_LORESERVE)
 242       shndx += this->elf_file_.large_shndx_offset();
 243     return shndx;
 244   }
 245
 246   // Find the dynamic symbol table and the version sections, given the
 247   // section headers.
 248   void
 249   find_dynsym_sections(const unsigned char* pshdrs,
 250                        unsigned int* pversym_shndx,
 251                        unsigned int* pverdef_shndx,
 252                        unsigned int* pverneed_shndx,
 253                        unsigned int* pdynamic_shndx);
 254
 255   // Read the dynamic symbol section SHNDX.
 256   void
 257   read_dynsym_section(const unsigned char* pshdrs, unsigned int shndx,
 258                       elfcpp::SHT type, unsigned int link,
 259                       File_view** view, section_size_type* view_size,
 260                       unsigned int* view_info);
 261
 262   // Read the dynamic tags.
 263   void
 264   read_dynamic(const unsigned char* pshdrs, unsigned int dynamic_shndx,
 265                unsigned int strtab_shndx, const unsigned char* strtabu,
 266                off_t strtab_size);
 267
 268   // Mapping from version number to version name.
 269   typedef std::vector<const char*> Version_map;
 270
 271   // Create the version map.
 272   void
 273   make_version_map(Read_symbols_data* sd, Version_map*) const;
 274
 275   // Add version definitions to the version map.
 276   void
 277   make_verdef_map(Read_symbols_data* sd, Version_map*) const;
 278
 279   // Add version references to the version map.
 280   void
 281   make_verneed_map(Read_symbols_data* sd, Version_map*) const;
 282
 283   // Add an entry to the version map.
 284   void
 285   set_version_map(Version_map*, unsigned int ndx, const char* name) const;
 286
 287   // General access to the ELF file.
 288   elfcpp::Elf_file<size, big_endian, Object> elf_file_;
 289   // The section index of the dynamic symbol table.
 290   unsigned int dynsym_shndx_;
 291 };
 292
 293 // A base class for Verdef and Verneed_version which just handles the
 294 // version index which will be stored in the SHT_GNU_versym section.
 295
 296 class Version_base
 297 {
 298  public:
 299   Version_base()
 300     : index_(-1U)
 301   { }
 302
 303   virtual
 304   ~Version_base()
 305   { }
 306
 307   // Return the version index.
 308   unsigned int
 309   index() const
 310   {
 311     gold_assert(this->index_ != -1U);
 312     return this->index_;
 313   }
 314
 315   // Set the version index.
 316   void
 317   set_index(unsigned int index)
 318   {
 319     gold_assert(this->index_ == -1U);
 320     this->index_ = index;
 321   }
 322
 323   // Clear the weak flag in a version definition.
 324   virtual void
 325   clear_weak() = 0;
 326
 327  private:
 328   Version_base(const Version_base&);
 329   Version_base& operator=(const Version_base&);
 330
 331   // The index of the version definition or reference.
 332   unsigned int index_;
 333 };
 334
 335 // This class handles a version being defined in the file we are
 336 // generating.
 337
 338 class Verdef : public Version_base
 339 {
 340  public:
 341   Verdef(const char* name, const std::vector<std::string>& deps,
 342          bool is_base, bool is_weak, bool is_symbol_created)
 343     : name_(name), deps_(deps), is_base_(is_base), is_weak_(is_weak),
 344       is_symbol_created_(is_symbol_created)
 345   { }
 346
 347   // Return the version name.
 348   const char*
 349   name() const
 350   { return this->name_; }
 351
 352   // Return the number of dependencies.
 353   unsigned int
 354   count_dependencies() const
 355   { return this->deps_.size(); }
 356
 357   // Add a dependency to this version.  The NAME should be
 358   // canonicalized in the dynamic Stringpool.
 359   void
 360   add_dependency(const char* name)
 361   { this->deps_.push_back(name); }
 362
 363   // Return whether this definition is weak.
 364   bool
 365   is_weak() const
 366   { return this->is_weak_; }
 367
 368   // Clear the weak flag.
 369   void
 370   clear_weak()
 371   { this->is_weak_ = false; }
 372
 373   // Return whether a version symbol has been created for this
 374   // definition.
 375   bool
 376   is_symbol_created() const
 377   { return this->is_symbol_created_; }
 378
 379   // Write contents to buffer.
 380   template<int size, bool big_endian>
 381   unsigned char*
 382   write(const Stringpool*, bool is_last, unsigned char*) const;
 383
 384  private:
 385   Verdef(const Verdef&);
 386   Verdef& operator=(const Verdef&);
 387
 388   // The type of the list of version dependencies.  Each dependency
 389   // should be canonicalized in the dynamic Stringpool.
 390   typedef std::vector<std::string> Deps;
 391
 392   // The name of this version.  This should be canonicalized in the
 393   // dynamic Stringpool.
 394   const char* name_;
 395   // A list of other versions which this version depends upon.
 396   Deps deps_;
 397   // Whether this is the base version.
 398   bool is_base_;
 399   // Whether this version is weak.
 400   bool is_weak_;
 401   // Whether a version symbol has been created.
 402   bool is_symbol_created_;
 403 };
 404
 405 // A referened version.  This will be associated with a filename by
 406 // Verneed.
 407
 408 class Verneed_version : public Version_base
 409 {
 410  public:
 411   Verneed_version(const char* version)
 412     : version_(version)
 413   { }
 414
 415   // Return the version name.
 416   const char*
 417   version() const
 418   { return this->version_; }
 419
 420   // Clear the weak flag.  This is invalid for a reference.
 421   void
 422   clear_weak()
 423   { gold_unreachable(); }
 424
 425  private:
 426   Verneed_version(const Verneed_version&);
 427   Verneed_version& operator=(const Verneed_version&);
 428
 429   const char* version_;
 430 };
 431
 432 // Version references in a single dynamic object.
 433
 434 class Verneed
 435 {
 436  public:
 437   Verneed(const char* filename)
 438     : filename_(filename), need_versions_()
 439   { }
 440
 441   ~Verneed();
 442
 443   // Return the file name.
 444   const char*
 445   filename() const
 446   { return this->filename_; }
 447
 448   // Return the number of versions.
 449   unsigned int
 450   count_versions() const
 451   { return this->need_versions_.size(); }
 452
 453   // Add a version name.  The name should be canonicalized in the
 454   // dynamic Stringpool.  If the name is already present, this does
 455   // nothing.
 456   Verneed_version*
 457   add_name(const char* name);
 458
 459   // Set the version indexes, starting at INDEX.  Return the updated
 460   // INDEX.
 461   unsigned int
 462   finalize(unsigned int index);
 463
 464   // Write contents to buffer.
 465   template<int size, bool big_endian>
 466   unsigned char*
 467   write(const Stringpool*, bool is_last, unsigned char*) const;
 468
 469  private:
 470   Verneed(const Verneed&);
 471   Verneed& operator=(const Verneed&);
 472
 473   // The type of the list of version names.  Each name should be
 474   // canonicalized in the dynamic Stringpool.
 475   typedef std::vector<Verneed_version*> Need_versions;
 476
 477   // The filename of the dynamic object.  This should be
 478   // canonicalized in the dynamic Stringpool.
 479   const char* filename_;
 480   // The list of version names.
 481   Need_versions need_versions_;
 482 };
 483
 484 // This class handles version definitions and references which go into
 485 // the output file.
 486
 487 class Versions
 488 {
 489  public:
 490   Versions(const Version_script_info&, Stringpool*);
 491
 492   ~Versions();
 493
 494   // SYM is going into the dynamic symbol table and has a version.
 495   // Record the appropriate version information.
 496   void
 497   record_version(const Symbol_table* symtab, Stringpool*, const Symbol* sym);
 498
 499   // Set the version indexes.  DYNSYM_INDEX is the index we should use
 500   // for the next dynamic symbol.  We add new dynamic symbols to SYMS
 501   // and return an updated DYNSYM_INDEX.
 502   unsigned int
 503   finalize(Symbol_table* symtab, unsigned int dynsym_index,
 504            std::vector<Symbol*>* syms);
 505
 506   // Return whether there are any version definitions.
 507   bool
 508   any_defs() const
 509   { return !this->defs_.empty(); }
 510
 511   // Return whether there are any version references.
 512   bool
 513   any_needs() const
 514   { return !this->needs_.empty(); }
 515
 516   // Build an allocated buffer holding the contents of the symbol
 517   // version section (.gnu.version).
 518   template<int size, bool big_endian>
 519   void
 520   symbol_section_contents(const Symbol_table*, const Stringpool*,
 521                           unsigned int local_symcount,
 522                           const std::vector<Symbol*>& syms,
 523                           unsigned char**, unsigned int*) const;
 524
 525   // Build an allocated buffer holding the contents of the version
 526   // definition section (.gnu.version_d).
 527   template<int size, bool big_endian>
 528   void
 529   def_section_contents(const Stringpool*, unsigned char**,
 530                        unsigned int* psize, unsigned int* pentries) const;
 531
 532   // Build an allocated buffer holding the contents of the version
 533   // reference section (.gnu.version_r).
 534   template<int size, bool big_endian>
 535   void
 536   need_section_contents(const Stringpool*, unsigned char**,
 537                         unsigned int* psize, unsigned int* pentries) const;
 538
 539   const Version_script_info&
 540   version_script() const
 541   { return this->version_script_; }
 542
 543  private:
 544   Versions(const Versions&);
 545   Versions& operator=(const Versions&);
 546
 547   // The type of the list of version definitions.
 548   typedef std::vector<Verdef*> Defs;
 549
 550   // The type of the list of version references.
 551   typedef std::vector<Verneed*> Needs;
 552
 553   // Handle a symbol SYM defined with version VERSION.
 554   void
 555   add_def(const Symbol* sym, const char* version, Stringpool::Key);
 556
 557   // Add a reference to version NAME in file FILENAME.
 558   void
 559   add_need(Stringpool*, const char* filename, const char* name,
 560            Stringpool::Key);
 561
 562   // Get the dynamic object to use for SYM.
 563   Dynobj*
 564   get_dynobj_for_sym(const Symbol_table*, const Symbol* sym) const;
 565
 566   // Return the version index to use for SYM.
 567   unsigned int
 568   version_index(const Symbol_table*, const Stringpool*,
 569                 const Symbol* sym) const;
 570
 571   // We keep a hash table mapping canonicalized name/version pairs to
 572   // a version base.
 573   typedef std::pair<Stringpool::Key, Stringpool::Key> Key;
 574
 575   struct Version_table_hash
 576   {
 577     size_t
 578     operator()(const Key& k) const
 579     { return k.first + k.second; }
 580   };
 581
 582   struct Version_table_eq
 583   {
 584     bool
 585     operator()(const Key& k1, const Key& k2) const
 586     { return k1.first == k2.first && k1.second == k2.second; }
 587   };
 588
 589   typedef Unordered_map<Key, Version_base*, Version_table_hash,
 590                         Version_table_eq> Version_table;
 591
 592   // The version definitions.
 593   Defs defs_;
 594   // The version references.
 595   Needs needs_;
 596   // The mapping from a canonicalized version/filename pair to a
 597   // version index.  The filename may be NULL.
 598   Version_table version_table_;
 599   // Whether the version indexes have been set.
 600   bool is_finalized_;
 601   // Contents of --version-script, if passed, or NULL.
 602   const Version_script_info& version_script_;
 603 };
 604
 605 } // End namespace gold.
 606
 607 #endif // !defined(GOLD_DYNOBJ_H)