gold/dynobj.h

   1 // dynobj.h -- dynamic object support for gold   -*- C++ -*-
   2
   3 // Copyright 2006, 2007 Free Software Foundation, Inc.
   4 // Written by Ian Lance Taylor <iant@google.com>.
   5
   6 // This file is part of gold.
   7
   8 // This program is free software; you can redistribute it and/or modify
   9 // it under the terms of the GNU General Public License as published by
  10 // the Free Software Foundation; either version 3 of the License, or
  11 // (at your option) any later version.
  12
  13 // This program is distributed in the hope that it will be useful,
  14 // but WITHOUT ANY WARRANTY; without even the implied warranty of
  15 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16 // GNU General Public License for more details.
  17
  18 // You should have received a copy of the GNU General Public License
  19 // along with this program; if not, write to the Free Software
  20 // Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,
  21 // MA 02110-1301, USA.
  22
  23 #ifndef GOLD_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  private:
 225   // For convenience.
 226   typedef Sized_dynobj<size, big_endian> This;
 227   static const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
 228   static const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
 229   static const int dyn_size = elfcpp::Elf_sizes<size>::dyn_size;
 230   typedef elfcpp::Shdr<size, big_endian> Shdr;
 231   typedef elfcpp::Dyn<size, big_endian> Dyn;
 232
 233   // Find the dynamic symbol table and the version sections, given the
 234   // section headers.
 235   void
 236   find_dynsym_sections(const unsigned char* pshdrs,
 237                        unsigned int* pdynshm_shndx,
 238                        unsigned int* pversym_shndx,
 239                        unsigned int* pverdef_shndx,
 240                        unsigned int* pverneed_shndx,
 241                        unsigned int* pdynamic_shndx);
 242
 243   // Read the dynamic symbol section SHNDX.
 244   void
 245   read_dynsym_section(const unsigned char* pshdrs, unsigned int shndx,
 246                       elfcpp::SHT type, unsigned int link,
 247                       File_view** view, section_size_type* view_size,
 248                       unsigned int* view_info);
 249
 250   // Read the dynamic tags.
 251   void
 252   read_dynamic(const unsigned char* pshdrs, unsigned int dynamic_shndx,
 253                unsigned int strtab_shndx, const unsigned char* strtabu,
 254                off_t strtab_size);
 255
 256   // Mapping from version number to version name.
 257   typedef std::vector<const char*> Version_map;
 258
 259   // Create the version map.
 260   void
 261   make_version_map(Read_symbols_data* sd, Version_map*) const;
 262
 263   // Add version definitions to the version map.
 264   void
 265   make_verdef_map(Read_symbols_data* sd, Version_map*) const;
 266
 267   // Add version references to the version map.
 268   void
 269   make_verneed_map(Read_symbols_data* sd, Version_map*) const;
 270
 271   // Add an entry to the version map.
 272   void
 273   set_version_map(Version_map*, unsigned int ndx, const char* name) const;
 274
 275   // General access to the ELF file.
 276   elfcpp::Elf_file<size, big_endian, Object> elf_file_;
 277 };
 278
 279 // A base class for Verdef and Verneed_version which just handles the
 280 // version index which will be stored in the SHT_GNU_versym section.
 281
 282 class Version_base
 283 {
 284  public:
 285   Version_base()
 286     : index_(-1U)
 287   { }
 288
 289   virtual
 290   ~Version_base()
 291   { }
 292
 293   // Return the version index.
 294   unsigned int
 295   index() const
 296   {
 297     gold_assert(this->index_ != -1U);
 298     return this->index_;
 299   }
 300
 301   // Set the version index.
 302   void
 303   set_index(unsigned int index)
 304   {
 305     gold_assert(this->index_ == -1U);
 306     this->index_ = index;
 307   }
 308
 309   // Clear the weak flag in a version definition.
 310   virtual void
 311   clear_weak() = 0;
 312
 313  private:
 314   Version_base(const Version_base&);
 315   Version_base& operator=(const Version_base&);
 316
 317   // The index of the version definition or reference.
 318   unsigned int index_;
 319 };
 320
 321 // This class handles a version being defined in the file we are
 322 // generating.
 323
 324 class Verdef : public Version_base
 325 {
 326  public:
 327   Verdef(const char* name, const std::vector<std::string>& deps,
 328          bool is_base, bool is_weak, bool is_symbol_created)
 329     : name_(name), deps_(deps), is_base_(is_base), is_weak_(is_weak),
 330       is_symbol_created_(is_symbol_created)
 331   { }
 332
 333   // Return the version name.
 334   const char*
 335   name() const
 336   { return this->name_; }
 337
 338   // Return the number of dependencies.
 339   unsigned int
 340   count_dependencies() const
 341   { return this->deps_.size(); }
 342
 343   // Add a dependency to this version.  The NAME should be
 344   // canonicalized in the dynamic Stringpool.
 345   void
 346   add_dependency(const char* name)
 347   { this->deps_.push_back(name); }
 348
 349   // Return whether this definition is weak.
 350   bool
 351   is_weak() const
 352   { return this->is_weak_; }
 353
 354   // Clear the weak flag.
 355   void
 356   clear_weak()
 357   { this->is_weak_ = false; }
 358
 359   // Return whether a version symbol has been created for this
 360   // definition.
 361   bool
 362   is_symbol_created() const
 363   { return this->is_symbol_created_; }
 364
 365   // Write contents to buffer.
 366   template<int size, bool big_endian>
 367   unsigned char*
 368   write(const Stringpool*, bool is_last, unsigned char*) const;
 369
 370  private:
 371   Verdef(const Verdef&);
 372   Verdef& operator=(const Verdef&);
 373
 374   // The type of the list of version dependencies.  Each dependency
 375   // should be canonicalized in the dynamic Stringpool.
 376   typedef std::vector<std::string> Deps;
 377
 378   // The name of this version.  This should be canonicalized in the
 379   // dynamic Stringpool.
 380   const char* name_;
 381   // A list of other versions which this version depends upon.
 382   Deps deps_;
 383   // Whether this is the base version.
 384   bool is_base_;
 385   // Whether this version is weak.
 386   bool is_weak_;
 387   // Whether a version symbol has been created.
 388   bool is_symbol_created_;
 389 };
 390
 391 // A referened version.  This will be associated with a filename by
 392 // Verneed.
 393
 394 class Verneed_version : public Version_base
 395 {
 396  public:
 397   Verneed_version(const char* version)
 398     : version_(version)
 399   { }
 400
 401   // Return the version name.
 402   const char*
 403   version() const
 404   { return this->version_; }
 405
 406   // Clear the weak flag.  This is invalid for a reference.
 407   void
 408   clear_weak()
 409   { gold_unreachable(); }
 410
 411  private:
 412   Verneed_version(const Verneed_version&);
 413   Verneed_version& operator=(const Verneed_version&);
 414
 415   const char* version_;
 416 };
 417
 418 // Version references in a single dynamic object.
 419
 420 class Verneed
 421 {
 422  public:
 423   Verneed(const char* filename)
 424     : filename_(filename), need_versions_()
 425   { }
 426
 427   ~Verneed();
 428
 429   // Return the file name.
 430   const char*
 431   filename() const
 432   { return this->filename_; }
 433
 434   // Return the number of versions.
 435   unsigned int
 436   count_versions() const
 437   { return this->need_versions_.size(); }
 438
 439   // Add a version name.  The name should be canonicalized in the
 440   // dynamic Stringpool.  If the name is already present, this does
 441   // nothing.
 442   Verneed_version*
 443   add_name(const char* name);
 444
 445   // Set the version indexes, starting at INDEX.  Return the updated
 446   // INDEX.
 447   unsigned int
 448   finalize(unsigned int index);
 449
 450   // Write contents to buffer.
 451   template<int size, bool big_endian>
 452   unsigned char*
 453   write(const Stringpool*, bool is_last, unsigned char*) const;
 454
 455  private:
 456   Verneed(const Verneed&);
 457   Verneed& operator=(const Verneed&);
 458
 459   // The type of the list of version names.  Each name should be
 460   // canonicalized in the dynamic Stringpool.
 461   typedef std::vector<Verneed_version*> Need_versions;
 462
 463   // The filename of the dynamic object.  This should be
 464   // canonicalized in the dynamic Stringpool.
 465   const char* filename_;
 466   // The list of version names.
 467   Need_versions need_versions_;
 468 };
 469
 470 // This class handles version definitions and references which go into
 471 // the output file.
 472
 473 class Versions
 474 {
 475  public:
 476   Versions(const Version_script_info&, Stringpool*);
 477
 478   ~Versions();
 479
 480   // SYM is going into the dynamic symbol table and has a version.
 481   // Record the appropriate version information.
 482   void
 483   record_version(const Symbol_table* symtab, Stringpool*, const Symbol* sym);
 484
 485   // Set the version indexes.  DYNSYM_INDEX is the index we should use
 486   // for the next dynamic symbol.  We add new dynamic symbols to SYMS
 487   // and return an updated DYNSYM_INDEX.
 488   unsigned int
 489   finalize(Symbol_table* symtab, unsigned int dynsym_index,
 490            std::vector<Symbol*>* syms);
 491
 492   // Return whether there are any version definitions.
 493   bool
 494   any_defs() const
 495   { return !this->defs_.empty(); }
 496
 497   // Return whether there are any version references.
 498   bool
 499   any_needs() const
 500   { return !this->needs_.empty(); }
 501
 502   // Build an allocated buffer holding the contents of the symbol
 503   // version section (.gnu.version).
 504   template<int size, bool big_endian>
 505   void
 506   symbol_section_contents(const Symbol_table*, const Stringpool*,
 507                           unsigned int local_symcount,
 508                           const std::vector<Symbol*>& syms,
 509                           unsigned char**, unsigned int*) const;
 510
 511   // Build an allocated buffer holding the contents of the version
 512   // definition section (.gnu.version_d).
 513   template<int size, bool big_endian>
 514   void
 515   def_section_contents(const Stringpool*, unsigned char**,
 516                        unsigned int* psize, unsigned int* pentries) const;
 517
 518   // Build an allocated buffer holding the contents of the version
 519   // reference section (.gnu.version_r).
 520   template<int size, bool big_endian>
 521   void
 522   need_section_contents(const Stringpool*, unsigned char**,
 523                         unsigned int* psize, unsigned int* pentries) const;
 524
 525   const Version_script_info&
 526   version_script() const
 527   { return this->version_script_; }
 528
 529  private:
 530   Versions(const Versions&);
 531   Versions& operator=(const Versions&);
 532
 533   // The type of the list of version definitions.
 534   typedef std::vector<Verdef*> Defs;
 535
 536   // The type of the list of version references.
 537   typedef std::vector<Verneed*> Needs;
 538
 539   // Handle a symbol SYM defined with version VERSION.
 540   void
 541   add_def(const Symbol* sym, const char* version, Stringpool::Key);
 542
 543   // Add a reference to version NAME in file FILENAME.
 544   void
 545   add_need(Stringpool*, const char* filename, const char* name,
 546            Stringpool::Key);
 547
 548   // Get the dynamic object to use for SYM.
 549   Dynobj*
 550   get_dynobj_for_sym(const Symbol_table*, const Symbol* sym) const;
 551
 552   // Return the version index to use for SYM.
 553   unsigned int
 554   version_index(const Symbol_table*, const Stringpool*,
 555                 const Symbol* sym) const;
 556
 557   // We keep a hash table mapping canonicalized name/version pairs to
 558   // a version base.
 559   typedef std::pair<Stringpool::Key, Stringpool::Key> Key;
 560
 561   struct Version_table_hash
 562   {
 563     size_t
 564     operator()(const Key& k) const
 565     { return k.first + k.second; }
 566   };
 567
 568   struct Version_table_eq
 569   {
 570     bool
 571     operator()(const Key& k1, const Key& k2) const
 572     { return k1.first == k2.first && k1.second == k2.second; }
 573   };
 574
 575   typedef Unordered_map<Key, Version_base*, Version_table_hash,
 576                         Version_table_eq> Version_table;
 577
 578   // The version definitions.
 579   Defs defs_;
 580   // The version references.
 581   Needs needs_;
 582   // The mapping from a canonicalized version/filename pair to a
 583   // version index.  The filename may be NULL.
 584   Version_table version_table_;
 585   // Whether the version indexes have been set.
 586   bool is_finalized_;
 587   // Contents of --version-script, if passed, or NULL.
 588   const Version_script_info& version_script_;
 589 };
 590
 591 } // End namespace gold.
 592
 593 #endif // !defined(GOLD_DYNOBJ_H)