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   Archive::Should_include
 181   do_should_include_member(Symbol_table* symtab, Layout*, Read_symbols_data*,
 182                            std::string* why);
 183
 184   // Get the size of a section.
 185   uint64_t
 186   do_section_size(unsigned int shndx)
 187   { return this->elf_file_.section_size(shndx); }
 188
 189   // Get the name of a section.
 190   std::string
 191   do_section_name(unsigned int shndx)
 192   { return this->elf_file_.section_name(shndx); }
 193
 194   // Return a view of the contents of a section.  Set *PLEN to the
 195   // size.
 196   Object::Location
 197   do_section_contents(unsigned int shndx)
 198   { return this->elf_file_.section_contents(shndx); }
 199
 200   // Return section flags.
 201   uint64_t
 202   do_section_flags(unsigned int shndx)
 203   { return this->elf_file_.section_flags(shndx); }
 204
 205   // Not used for dynobj.
 206   uint64_t
 207   do_section_entsize(unsigned int )
 208   { gold_unreachable(); }
 209
 210   // Return section address.
 211   uint64_t
 212   do_section_address(unsigned int shndx)
 213   { return this->elf_file_.section_addr(shndx); }
 214
 215   // Return section type.
 216   unsigned int
 217   do_section_type(unsigned int shndx)
 218   { return this->elf_file_.section_type(shndx); }
 219
 220   // Return the section link field.
 221   unsigned int
 222   do_section_link(unsigned int shndx)
 223   { return this->elf_file_.section_link(shndx); }
 224
 225   // Return the section link field.
 226   unsigned int
 227   do_section_info(unsigned int shndx)
 228   { return this->elf_file_.section_info(shndx); }
 229
 230   // Return the section alignment.
 231   uint64_t
 232   do_section_addralign(unsigned int shndx)
 233   { return this->elf_file_.section_addralign(shndx); }
 234
 235   // Return the Xindex structure to use.
 236   Xindex*
 237   do_initialize_xindex();
 238
 239   // Get symbol counts.
 240   void
 241   do_get_global_symbol_counts(const Symbol_table*, size_t*, size_t*) const;
 242
 243   // Get the global symbols.
 244   const Symbols*
 245   do_get_global_symbols() const
 246   { return this->symbols_; }
 247
 248  private:
 249   // For convenience.
 250   typedef Sized_dynobj<size, big_endian> This;
 251   static const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
 252   static const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
 253   static const int dyn_size = elfcpp::Elf_sizes<size>::dyn_size;
 254   typedef elfcpp::Shdr<size, big_endian> Shdr;
 255   typedef elfcpp::Dyn<size, big_endian> Dyn;
 256
 257   // Adjust a section index if necessary.
 258   unsigned int
 259   adjust_shndx(unsigned int shndx)
 260   {
 261     if (shndx >= elfcpp::SHN_LORESERVE)
 262       shndx += this->elf_file_.large_shndx_offset();
 263     return shndx;
 264   }
 265
 266   // Find the dynamic symbol table and the version sections, given the
 267   // section headers.
 268   void
 269   find_dynsym_sections(const unsigned char* pshdrs,
 270                        unsigned int* pversym_shndx,
 271                        unsigned int* pverdef_shndx,
 272                        unsigned int* pverneed_shndx,
 273                        unsigned int* pdynamic_shndx);
 274
 275   // Read the dynamic symbol section SHNDX.
 276   void
 277   read_dynsym_section(const unsigned char* pshdrs, unsigned int shndx,
 278                       elfcpp::SHT type, unsigned int link,
 279                       File_view** view, section_size_type* view_size,
 280                       unsigned int* view_info);
 281
 282   // Read the dynamic tags.
 283   void
 284   read_dynamic(const unsigned char* pshdrs, unsigned int dynamic_shndx,
 285                unsigned int strtab_shndx, const unsigned char* strtabu,
 286                off_t strtab_size);
 287
 288   // Mapping from version number to version name.
 289   typedef std::vector<const char*> Version_map;
 290
 291   // Create the version map.
 292   void
 293   make_version_map(Read_symbols_data* sd, Version_map*) const;
 294
 295   // Add version definitions to the version map.
 296   void
 297   make_verdef_map(Read_symbols_data* sd, Version_map*) const;
 298
 299   // Add version references to the version map.
 300   void
 301   make_verneed_map(Read_symbols_data* sd, Version_map*) const;
 302
 303   // Add an entry to the version map.
 304   void
 305   set_version_map(Version_map*, unsigned int ndx, const char* name) const;
 306
 307   // General access to the ELF file.
 308   elfcpp::Elf_file<size, big_endian, Object> elf_file_;
 309   // The section index of the dynamic symbol table.
 310   unsigned int dynsym_shndx_;
 311   // The entries in the symbol table for the symbols.  We only keep
 312   // this if we need it to print symbol information.
 313   Symbols* symbols_;
 314   // Number of defined symbols.
 315   size_t defined_count_;
 316 };
 317
 318 // A base class for Verdef and Verneed_version which just handles the
 319 // version index which will be stored in the SHT_GNU_versym section.
 320
 321 class Version_base
 322 {
 323  public:
 324   Version_base()
 325     : index_(-1U)
 326   { }
 327
 328   virtual
 329   ~Version_base()
 330   { }
 331
 332   // Return the version index.
 333   unsigned int
 334   index() const
 335   {
 336     gold_assert(this->index_ != -1U);
 337     return this->index_;
 338   }
 339
 340   // Set the version index.
 341   void
 342   set_index(unsigned int index)
 343   {
 344     gold_assert(this->index_ == -1U);
 345     this->index_ = index;
 346   }
 347
 348   // Clear the weak flag in a version definition.
 349   virtual void
 350   clear_weak() = 0;
 351
 352  private:
 353   Version_base(const Version_base&);
 354   Version_base& operator=(const Version_base&);
 355
 356   // The index of the version definition or reference.
 357   unsigned int index_;
 358 };
 359
 360 // This class handles a version being defined in the file we are
 361 // generating.
 362
 363 class Verdef : public Version_base
 364 {
 365  public:
 366   Verdef(const char* name, const std::vector<std::string>& deps,
 367          bool is_base, bool is_weak, bool is_info, bool is_symbol_created)
 368     : name_(name), deps_(deps), is_base_(is_base), is_weak_(is_weak),
 369       is_info_(is_info), is_symbol_created_(is_symbol_created)
 370   { }
 371
 372   // Return the version name.
 373   const char*
 374   name() const
 375   { return this->name_; }
 376
 377   // Return the number of dependencies.
 378   unsigned int
 379   count_dependencies() const
 380   { return this->deps_.size(); }
 381
 382   // Add a dependency to this version.  The NAME should be
 383   // canonicalized in the dynamic Stringpool.
 384   void
 385   add_dependency(const char* name)
 386   { this->deps_.push_back(name); }
 387
 388   // Return whether this definition is weak.
 389   bool
 390   is_weak() const
 391   { return this->is_weak_; }
 392
 393   // Clear the weak flag.
 394   void
 395   clear_weak()
 396   { this->is_weak_ = false; }
 397
 398   // Return whether this definition is informational.
 399   bool
 400   is_info() const
 401   { return this->is_info_; }
 402
 403   // Return whether a version symbol has been created for this
 404   // definition.
 405   bool
 406   is_symbol_created() const
 407   { return this->is_symbol_created_; }
 408
 409   // Write contents to buffer.
 410   template<int size, bool big_endian>
 411   unsigned char*
 412   write(const Stringpool*, bool is_last, unsigned char*) const;
 413
 414  private:
 415   Verdef(const Verdef&);
 416   Verdef& operator=(const Verdef&);
 417
 418   // The type of the list of version dependencies.  Each dependency
 419   // should be canonicalized in the dynamic Stringpool.
 420   typedef std::vector<std::string> Deps;
 421
 422   // The name of this version.  This should be canonicalized in the
 423   // dynamic Stringpool.
 424   const char* name_;
 425   // A list of other versions which this version depends upon.
 426   Deps deps_;
 427   // Whether this is the base version.
 428   bool is_base_;
 429   // Whether this version is weak.
 430   bool is_weak_;
 431   // Whether this version is informational.
 432   bool is_info_;
 433   // Whether a version symbol has been created.
 434   bool is_symbol_created_;
 435 };
 436
 437 // A referened version.  This will be associated with a filename by
 438 // Verneed.
 439
 440 class Verneed_version : public Version_base
 441 {
 442  public:
 443   Verneed_version(const char* version)
 444     : version_(version)
 445   { }
 446
 447   // Return the version name.
 448   const char*
 449   version() const
 450   { return this->version_; }
 451
 452   // Clear the weak flag.  This is invalid for a reference.
 453   void
 454   clear_weak()
 455   { gold_unreachable(); }
 456
 457  private:
 458   Verneed_version(const Verneed_version&);
 459   Verneed_version& operator=(const Verneed_version&);
 460
 461   const char* version_;
 462 };
 463
 464 // Version references in a single dynamic object.
 465
 466 class Verneed
 467 {
 468  public:
 469   Verneed(const char* filename)
 470     : filename_(filename), need_versions_()
 471   { }
 472
 473   ~Verneed();
 474
 475   // Return the file name.
 476   const char*
 477   filename() const
 478   { return this->filename_; }
 479
 480   // Return the number of versions.
 481   unsigned int
 482   count_versions() const
 483   { return this->need_versions_.size(); }
 484
 485   // Add a version name.  The name should be canonicalized in the
 486   // dynamic Stringpool.  If the name is already present, this does
 487   // nothing.
 488   Verneed_version*
 489   add_name(const char* name);
 490
 491   // Set the version indexes, starting at INDEX.  Return the updated
 492   // INDEX.
 493   unsigned int
 494   finalize(unsigned int index);
 495
 496   // Write contents to buffer.
 497   template<int size, bool big_endian>
 498   unsigned char*
 499   write(const Stringpool*, bool is_last, unsigned char*) const;
 500
 501  private:
 502   Verneed(const Verneed&);
 503   Verneed& operator=(const Verneed&);
 504
 505   // The type of the list of version names.  Each name should be
 506   // canonicalized in the dynamic Stringpool.
 507   typedef std::vector<Verneed_version*> Need_versions;
 508
 509   // The filename of the dynamic object.  This should be
 510   // canonicalized in the dynamic Stringpool.
 511   const char* filename_;
 512   // The list of version names.
 513   Need_versions need_versions_;
 514 };
 515
 516 // This class handles version definitions and references which go into
 517 // the output file.
 518
 519 class Versions
 520 {
 521  public:
 522   Versions(const Version_script_info&, Stringpool*);
 523
 524   ~Versions();
 525
 526   // SYM is going into the dynamic symbol table and has a version.
 527   // Record the appropriate version information.
 528   void
 529   record_version(const Symbol_table* symtab, Stringpool*, const Symbol* sym);
 530
 531   // Set the version indexes.  DYNSYM_INDEX is the index we should use
 532   // for the next dynamic symbol.  We add new dynamic symbols to SYMS
 533   // and return an updated DYNSYM_INDEX.
 534   unsigned int
 535   finalize(Symbol_table* symtab, unsigned int dynsym_index,
 536            std::vector<Symbol*>* syms);
 537
 538   // Return whether there are any version definitions.
 539   bool
 540   any_defs() const
 541   { return !this->defs_.empty(); }
 542
 543   // Return whether there are any version references.
 544   bool
 545   any_needs() const
 546   { return !this->needs_.empty(); }
 547
 548   // Build an allocated buffer holding the contents of the symbol
 549   // version section (.gnu.version).
 550   template<int size, bool big_endian>
 551   void
 552   symbol_section_contents(const Symbol_table*, const Stringpool*,
 553                           unsigned int local_symcount,
 554                           const std::vector<Symbol*>& syms,
 555                           unsigned char**, unsigned int*) const;
 556
 557   // Build an allocated buffer holding the contents of the version
 558   // definition section (.gnu.version_d).
 559   template<int size, bool big_endian>
 560   void
 561   def_section_contents(const Stringpool*, unsigned char**,
 562                        unsigned int* psize, unsigned int* pentries) const;
 563
 564   // Build an allocated buffer holding the contents of the version
 565   // reference section (.gnu.version_r).
 566   template<int size, bool big_endian>
 567   void
 568   need_section_contents(const Stringpool*, unsigned char**,
 569                         unsigned int* psize, unsigned int* pentries) const;
 570
 571   const Version_script_info&
 572   version_script() const
 573   { return this->version_script_; }
 574
 575  private:
 576   Versions(const Versions&);
 577   Versions& operator=(const Versions&);
 578
 579   // The type of the list of version definitions.
 580   typedef std::vector<Verdef*> Defs;
 581
 582   // The type of the list of version references.
 583   typedef std::vector<Verneed*> Needs;
 584
 585   // Handle a symbol SYM defined with version VERSION.
 586   void
 587   add_def(const Symbol* sym, const char* version, Stringpool::Key);
 588
 589   // Add a reference to version NAME in file FILENAME.
 590   void
 591   add_need(Stringpool*, const char* filename, const char* name,
 592            Stringpool::Key);
 593
 594   // Get the dynamic object to use for SYM.
 595   Dynobj*
 596   get_dynobj_for_sym(const Symbol_table*, const Symbol* sym) const;
 597
 598   // Return the version index to use for SYM.
 599   unsigned int
 600   version_index(const Symbol_table*, const Stringpool*,
 601                 const Symbol* sym) const;
 602
 603   // Define the base version of a shared library.
 604   void
 605   define_base_version(Stringpool* dynpool);
 606
 607   // We keep a hash table mapping canonicalized name/version pairs to
 608   // a version base.
 609   typedef std::pair<Stringpool::Key, Stringpool::Key> Key;
 610
 611   struct Version_table_hash
 612   {
 613     size_t
 614     operator()(const Key& k) const
 615     { return k.first + k.second; }
 616   };
 617
 618   struct Version_table_eq
 619   {
 620     bool
 621     operator()(const Key& k1, const Key& k2) const
 622     { return k1.first == k2.first && k1.second == k2.second; }
 623   };
 624
 625   typedef Unordered_map<Key, Version_base*, Version_table_hash,
 626                         Version_table_eq> Version_table;
 627
 628   // The version definitions.
 629   Defs defs_;
 630   // The version references.
 631   Needs needs_;
 632   // The mapping from a canonicalized version/filename pair to a
 633   // version index.  The filename may be NULL.
 634   Version_table version_table_;
 635   // Whether the version indexes have been set.
 636   bool is_finalized_;
 637   // Contents of --version-script, if passed, or NULL.
 638   const Version_script_info& version_script_;
 639   // Whether we need to insert a base version.  This is only used for
 640   // shared libaries and is cleared when the base version is defined.
 641   bool needs_base_version_;
 642 };
 643
 644 } // End namespace gold.
 645
 646 #endif // !defined(GOLD_DYNOBJ_H)