gold/dynobj.h

   1 // dynobj.h -- dynamic object support for gold   -*- C++ -*-
   2
   3 // Copyright 2006, 2007, 2008, 2009, 2010 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   typedef typename Sized_relobj<size, big_endian>::Symbols Symbols;
 160
 161   Sized_dynobj(const std::string& name, Input_file* input_file, off_t offset,
 162                const typename elfcpp::Ehdr<size, big_endian>&);
 163
 164   // Set up the object file based on TARGET.
 165   void
 166   setup();
 167
 168   // Read the symbols.
 169   void
 170   do_read_symbols(Read_symbols_data*);
 171
 172   // Lay out the input sections.
 173   void
 174   do_layout(Symbol_table*, Layout*, Read_symbols_data*);
 175
 176   // Add the symbols to the symbol table.
 177   void
 178   do_add_symbols(Symbol_table*, Read_symbols_data*, Layout*);
 179
 180   // Get the size of a section.
 181   uint64_t
 182   do_section_size(unsigned int shndx)
 183   { return this->elf_file_.section_size(shndx); }
 184
 185   // Get the name of a section.
 186   std::string
 187   do_section_name(unsigned int shndx)
 188   { return this->elf_file_.section_name(shndx); }
 189
 190   // Return a view of the contents of a section.  Set *PLEN to the
 191   // size.
 192   Object::Location
 193   do_section_contents(unsigned int shndx)
 194   { return this->elf_file_.section_contents(shndx); }
 195
 196   // Return section flags.
 197   uint64_t
 198   do_section_flags(unsigned int shndx)
 199   { return this->elf_file_.section_flags(shndx); }
 200
 201   // Not used for dynobj.
 202   uint64_t
 203   do_section_entsize(unsigned int )
 204   { gold_unreachable(); }
 205
 206   // Return section address.
 207   uint64_t
 208   do_section_address(unsigned int shndx)
 209   { return this->elf_file_.section_addr(shndx); }
 210
 211   // Return section type.
 212   unsigned int
 213   do_section_type(unsigned int shndx)
 214   { return this->elf_file_.section_type(shndx); }
 215
 216   // Return the section link field.
 217   unsigned int
 218   do_section_link(unsigned int shndx)
 219   { return this->elf_file_.section_link(shndx); }
 220
 221   // Return the section link field.
 222   unsigned int
 223   do_section_info(unsigned int shndx)
 224   { return this->elf_file_.section_info(shndx); }
 225
 226   // Return the section alignment.
 227   uint64_t
 228   do_section_addralign(unsigned int shndx)
 229   { return this->elf_file_.section_addralign(shndx); }
 230
 231   // Return the Xindex structure to use.
 232   Xindex*
 233   do_initialize_xindex();
 234
 235   // Get symbol counts.
 236   void
 237   do_get_global_symbol_counts(const Symbol_table*, size_t*, size_t*) const;
 238
 239   // Get the global symbols.
 240   const Symbols*
 241   do_get_global_symbols() const
 242   { return this->symbols_; }
 243
 244  private:
 245   // For convenience.
 246   typedef Sized_dynobj<size, big_endian> This;
 247   static const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
 248   static const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
 249   static const int dyn_size = elfcpp::Elf_sizes<size>::dyn_size;
 250   typedef elfcpp::Shdr<size, big_endian> Shdr;
 251   typedef elfcpp::Dyn<size, big_endian> Dyn;
 252
 253   // Adjust a section index if necessary.
 254   unsigned int
 255   adjust_shndx(unsigned int shndx)
 256   {
 257     if (shndx >= elfcpp::SHN_LORESERVE)
 258       shndx += this->elf_file_.large_shndx_offset();
 259     return shndx;
 260   }
 261
 262   // Find the dynamic symbol table and the version sections, given the
 263   // section headers.
 264   void
 265   find_dynsym_sections(const unsigned char* pshdrs,
 266                        unsigned int* pversym_shndx,
 267                        unsigned int* pverdef_shndx,
 268                        unsigned int* pverneed_shndx,
 269                        unsigned int* pdynamic_shndx);
 270
 271   // Read the dynamic symbol section SHNDX.
 272   void
 273   read_dynsym_section(const unsigned char* pshdrs, unsigned int shndx,
 274                       elfcpp::SHT type, unsigned int link,
 275                       File_view** view, section_size_type* view_size,
 276                       unsigned int* view_info);
 277
 278   // Read the dynamic tags.
 279   void
 280   read_dynamic(const unsigned char* pshdrs, unsigned int dynamic_shndx,
 281                unsigned int strtab_shndx, const unsigned char* strtabu,
 282                off_t strtab_size);
 283
 284   // Mapping from version number to version name.
 285   typedef std::vector<const char*> Version_map;
 286
 287   // Create the version map.
 288   void
 289   make_version_map(Read_symbols_data* sd, Version_map*) const;
 290
 291   // Add version definitions to the version map.
 292   void
 293   make_verdef_map(Read_symbols_data* sd, Version_map*) const;
 294
 295   // Add version references to the version map.
 296   void
 297   make_verneed_map(Read_symbols_data* sd, Version_map*) const;
 298
 299   // Add an entry to the version map.
 300   void
 301   set_version_map(Version_map*, unsigned int ndx, const char* name) const;
 302
 303   // General access to the ELF file.
 304   elfcpp::Elf_file<size, big_endian, Object> elf_file_;
 305   // The section index of the dynamic symbol table.
 306   unsigned int dynsym_shndx_;
 307   // The entries in the symbol table for the symbols.  We only keep
 308   // this if we need it to print symbol information.
 309   Symbols* symbols_;
 310   // Number of defined symbols.
 311   size_t defined_count_;
 312 };
 313
 314 // A base class for Verdef and Verneed_version which just handles the
 315 // version index which will be stored in the SHT_GNU_versym section.
 316
 317 class Version_base
 318 {
 319  public:
 320   Version_base()
 321     : index_(-1U)
 322   { }
 323
 324   virtual
 325   ~Version_base()
 326   { }
 327
 328   // Return the version index.
 329   unsigned int
 330   index() const
 331   {
 332     gold_assert(this->index_ != -1U);
 333     return this->index_;
 334   }
 335
 336   // Set the version index.
 337   void
 338   set_index(unsigned int index)
 339   {
 340     gold_assert(this->index_ == -1U);
 341     this->index_ = index;
 342   }
 343
 344   // Clear the weak flag in a version definition.
 345   virtual void
 346   clear_weak() = 0;
 347
 348  private:
 349   Version_base(const Version_base&);
 350   Version_base& operator=(const Version_base&);
 351
 352   // The index of the version definition or reference.
 353   unsigned int index_;
 354 };
 355
 356 // This class handles a version being defined in the file we are
 357 // generating.
 358
 359 class Verdef : public Version_base
 360 {
 361  public:
 362   Verdef(const char* name, const std::vector<std::string>& deps,
 363          bool is_base, bool is_weak, bool is_info, bool is_symbol_created)
 364     : name_(name), deps_(deps), is_base_(is_base), is_weak_(is_weak),
 365       is_info_(is_info), is_symbol_created_(is_symbol_created)
 366   { }
 367
 368   // Return the version name.
 369   const char*
 370   name() const
 371   { return this->name_; }
 372
 373   // Return the number of dependencies.
 374   unsigned int
 375   count_dependencies() const
 376   { return this->deps_.size(); }
 377
 378   // Add a dependency to this version.  The NAME should be
 379   // canonicalized in the dynamic Stringpool.
 380   void
 381   add_dependency(const char* name)
 382   { this->deps_.push_back(name); }
 383
 384   // Return whether this definition is weak.
 385   bool
 386   is_weak() const
 387   { return this->is_weak_; }
 388
 389   // Clear the weak flag.
 390   void
 391   clear_weak()
 392   { this->is_weak_ = false; }
 393
 394   // Return whether this definition is informational.
 395   bool
 396   is_info() const
 397   { return this->is_info_; }
 398
 399   // Return whether a version symbol has been created for this
 400   // definition.
 401   bool
 402   is_symbol_created() const
 403   { return this->is_symbol_created_; }
 404
 405   // Write contents to buffer.
 406   template<int size, bool big_endian>
 407   unsigned char*
 408   write(const Stringpool*, bool is_last, unsigned char*) const;
 409
 410  private:
 411   Verdef(const Verdef&);
 412   Verdef& operator=(const Verdef&);
 413
 414   // The type of the list of version dependencies.  Each dependency
 415   // should be canonicalized in the dynamic Stringpool.
 416   typedef std::vector<std::string> Deps;
 417
 418   // The name of this version.  This should be canonicalized in the
 419   // dynamic Stringpool.
 420   const char* name_;
 421   // A list of other versions which this version depends upon.
 422   Deps deps_;
 423   // Whether this is the base version.
 424   bool is_base_;
 425   // Whether this version is weak.
 426   bool is_weak_;
 427   // Whether this version is informational.
 428   bool is_info_;
 429   // Whether a version symbol has been created.
 430   bool is_symbol_created_;
 431 };
 432
 433 // A referened version.  This will be associated with a filename by
 434 // Verneed.
 435
 436 class Verneed_version : public Version_base
 437 {
 438  public:
 439   Verneed_version(const char* version)
 440     : version_(version)
 441   { }
 442
 443   // Return the version name.
 444   const char*
 445   version() const
 446   { return this->version_; }
 447
 448   // Clear the weak flag.  This is invalid for a reference.
 449   void
 450   clear_weak()
 451   { gold_unreachable(); }
 452
 453  private:
 454   Verneed_version(const Verneed_version&);
 455   Verneed_version& operator=(const Verneed_version&);
 456
 457   const char* version_;
 458 };
 459
 460 // Version references in a single dynamic object.
 461
 462 class Verneed
 463 {
 464  public:
 465   Verneed(const char* filename)
 466     : filename_(filename), need_versions_()
 467   { }
 468
 469   ~Verneed();
 470
 471   // Return the file name.
 472   const char*
 473   filename() const
 474   { return this->filename_; }
 475
 476   // Return the number of versions.
 477   unsigned int
 478   count_versions() const
 479   { return this->need_versions_.size(); }
 480
 481   // Add a version name.  The name should be canonicalized in the
 482   // dynamic Stringpool.  If the name is already present, this does
 483   // nothing.
 484   Verneed_version*
 485   add_name(const char* name);
 486
 487   // Set the version indexes, starting at INDEX.  Return the updated
 488   // INDEX.
 489   unsigned int
 490   finalize(unsigned int index);
 491
 492   // Write contents to buffer.
 493   template<int size, bool big_endian>
 494   unsigned char*
 495   write(const Stringpool*, bool is_last, unsigned char*) const;
 496
 497  private:
 498   Verneed(const Verneed&);
 499   Verneed& operator=(const Verneed&);
 500
 501   // The type of the list of version names.  Each name should be
 502   // canonicalized in the dynamic Stringpool.
 503   typedef std::vector<Verneed_version*> Need_versions;
 504
 505   // The filename of the dynamic object.  This should be
 506   // canonicalized in the dynamic Stringpool.
 507   const char* filename_;
 508   // The list of version names.
 509   Need_versions need_versions_;
 510 };
 511
 512 // This class handles version definitions and references which go into
 513 // the output file.
 514
 515 class Versions
 516 {
 517  public:
 518   Versions(const Version_script_info&, Stringpool*);
 519
 520   ~Versions();
 521
 522   // SYM is going into the dynamic symbol table and has a version.
 523   // Record the appropriate version information.
 524   void
 525   record_version(const Symbol_table* symtab, Stringpool*, const Symbol* sym);
 526
 527   // Set the version indexes.  DYNSYM_INDEX is the index we should use
 528   // for the next dynamic symbol.  We add new dynamic symbols to SYMS
 529   // and return an updated DYNSYM_INDEX.
 530   unsigned int
 531   finalize(Symbol_table* symtab, unsigned int dynsym_index,
 532            std::vector<Symbol*>* syms);
 533
 534   // Return whether there are any version definitions.
 535   bool
 536   any_defs() const
 537   { return !this->defs_.empty(); }
 538
 539   // Return whether there are any version references.
 540   bool
 541   any_needs() const
 542   { return !this->needs_.empty(); }
 543
 544   // Build an allocated buffer holding the contents of the symbol
 545   // version section (.gnu.version).
 546   template<int size, bool big_endian>
 547   void
 548   symbol_section_contents(const Symbol_table*, const Stringpool*,
 549                           unsigned int local_symcount,
 550                           const std::vector<Symbol*>& syms,
 551                           unsigned char**, unsigned int*) const;
 552
 553   // Build an allocated buffer holding the contents of the version
 554   // definition section (.gnu.version_d).
 555   template<int size, bool big_endian>
 556   void
 557   def_section_contents(const Stringpool*, unsigned char**,
 558                        unsigned int* psize, unsigned int* pentries) const;
 559
 560   // Build an allocated buffer holding the contents of the version
 561   // reference section (.gnu.version_r).
 562   template<int size, bool big_endian>
 563   void
 564   need_section_contents(const Stringpool*, unsigned char**,
 565                         unsigned int* psize, unsigned int* pentries) const;
 566
 567   const Version_script_info&
 568   version_script() const
 569   { return this->version_script_; }
 570
 571  private:
 572   Versions(const Versions&);
 573   Versions& operator=(const Versions&);
 574
 575   // The type of the list of version definitions.
 576   typedef std::vector<Verdef*> Defs;
 577
 578   // The type of the list of version references.
 579   typedef std::vector<Verneed*> Needs;
 580
 581   // Handle a symbol SYM defined with version VERSION.
 582   void
 583   add_def(const Symbol* sym, const char* version, Stringpool::Key);
 584
 585   // Add a reference to version NAME in file FILENAME.
 586   void
 587   add_need(Stringpool*, const char* filename, const char* name,
 588            Stringpool::Key);
 589
 590   // Get the dynamic object to use for SYM.
 591   Dynobj*
 592   get_dynobj_for_sym(const Symbol_table*, const Symbol* sym) const;
 593
 594   // Return the version index to use for SYM.
 595   unsigned int
 596   version_index(const Symbol_table*, const Stringpool*,
 597                 const Symbol* sym) const;
 598
 599   // Define the base version of a shared library.
 600   void
 601   define_base_version(Stringpool* dynpool);
 602
 603   // We keep a hash table mapping canonicalized name/version pairs to
 604   // a version base.
 605   typedef std::pair<Stringpool::Key, Stringpool::Key> Key;
 606
 607   struct Version_table_hash
 608   {
 609     size_t
 610     operator()(const Key& k) const
 611     { return k.first + k.second; }
 612   };
 613
 614   struct Version_table_eq
 615   {
 616     bool
 617     operator()(const Key& k1, const Key& k2) const
 618     { return k1.first == k2.first && k1.second == k2.second; }
 619   };
 620
 621   typedef Unordered_map<Key, Version_base*, Version_table_hash,
 622                         Version_table_eq> Version_table;
 623
 624   // The version definitions.
 625   Defs defs_;
 626   // The version references.
 627   Needs needs_;
 628   // The mapping from a canonicalized version/filename pair to a
 629   // version index.  The filename may be NULL.
 630   Version_table version_table_;
 631   // Whether the version indexes have been set.
 632   bool is_finalized_;
 633   // Contents of --version-script, if passed, or NULL.
 634   const Version_script_info& version_script_;
 635   // Whether we need to insert a base version.  This is only used for
 636   // shared libaries and is cleared when the base version is defined.
 637   bool needs_base_version_;
 638 };
 639
 640 } // End namespace gold.
 641
 642 #endif // !defined(GOLD_DYNOBJ_H)