gold/dynobj.h

   1 // dynobj.h -- dynamic object support for gold   -*- C++ -*-
   2
   3 // Copyright 2006, 2007, 2008, 2009, 2010, 2011  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   // Return a pointer to this object.
 100   virtual Dynobj*
 101   do_dynobj()
 102   { return this; }
 103
 104   // Set the DT_SONAME string.
 105   void
 106   set_soname_string(const char* s)
 107   { this->soname_.assign(s); }
 108
 109   // Add an entry to the list of DT_NEEDED strings.
 110   void
 111   add_needed(const char* s)
 112   { this->needed_.push_back(std::string(s)); }
 113
 114  private:
 115   // Compute the GNU hash code for a string.
 116   static uint32_t
 117   gnu_hash(const char*);
 118
 119   // Compute the number of hash buckets to use.
 120   static unsigned int
 121   compute_bucket_count(const std::vector<uint32_t>& hashcodes,
 122                        bool for_gnu_hash_table);
 123
 124   // Sized version of create_elf_hash_table.
 125   template<bool big_endian>
 126   static void
 127   sized_create_elf_hash_table(const std::vector<uint32_t>& bucket,
 128                               const std::vector<uint32_t>& chain,
 129                               unsigned char* phash,
 130                               unsigned int hashlen);
 131
 132   // Sized version of create_gnu_hash_table.
 133   template<int size, bool big_endian>
 134   static void
 135   sized_create_gnu_hash_table(const std::vector<Symbol*>& hashed_dynsyms,
 136                               const std::vector<uint32_t>& dynsym_hashvals,
 137                               unsigned int unhashed_dynsym_count,
 138                               unsigned char** pphash,
 139                               unsigned int* phashlen);
 140
 141   // Values for the has_unknown_needed_entries_ field.
 142   enum Unknown_needed
 143   {
 144     UNKNOWN_NEEDED_UNSET,
 145     UNKNOWN_NEEDED_TRUE,
 146     UNKNOWN_NEEDED_FALSE
 147   };
 148
 149   // The DT_SONAME name, if any.
 150   std::string soname_;
 151   // The list of DT_NEEDED entries.
 152   Needed needed_;
 153   // Whether this dynamic object has any DT_NEEDED entries not seen
 154   // during the link.
 155   Unknown_needed unknown_needed_;
 156 };
 157
 158 // A dynamic object, size and endian specific version.
 159
 160 template<int size, bool big_endian>
 161 class Sized_dynobj : public Dynobj
 162 {
 163  public:
 164   typedef typename Sized_relobj_file<size, big_endian>::Symbols Symbols;
 165
 166   Sized_dynobj(const std::string& name, Input_file* input_file, off_t offset,
 167                const typename elfcpp::Ehdr<size, big_endian>&);
 168
 169   // Set up the object file based on TARGET.
 170   void
 171   setup();
 172
 173   // Read the symbols.
 174   void
 175   do_read_symbols(Read_symbols_data*);
 176
 177   // Lay out the input sections.
 178   void
 179   do_layout(Symbol_table*, Layout*, Read_symbols_data*);
 180
 181   // Add the symbols to the symbol table.
 182   void
 183   do_add_symbols(Symbol_table*, Read_symbols_data*, Layout*);
 184
 185   Archive::Should_include
 186   do_should_include_member(Symbol_table* symtab, Layout*, Read_symbols_data*,
 187                            std::string* why);
 188
 189   // Iterate over global symbols, calling a visitor class V for each.
 190   void
 191   do_for_all_global_symbols(Read_symbols_data* sd,
 192                             Library_base::Symbol_visitor_base* v);
 193
 194   // Iterate over local symbols, calling a visitor class V for each GOT offset
 195   // associated with a local symbol.
 196   void
 197   do_for_all_local_got_entries(Got_offset_list::Visitor* v) const;
 198
 199   // Get the size of a section.
 200   uint64_t
 201   do_section_size(unsigned int shndx)
 202   { return this->elf_file_.section_size(shndx); }
 203
 204   // Get the name of a section.
 205   std::string
 206   do_section_name(unsigned int shndx)
 207   { return this->elf_file_.section_name(shndx); }
 208
 209   // Return a view of the contents of a section.  Set *PLEN to the
 210   // size.
 211   Object::Location
 212   do_section_contents(unsigned int shndx)
 213   { return this->elf_file_.section_contents(shndx); }
 214
 215   // Return section flags.
 216   uint64_t
 217   do_section_flags(unsigned int shndx)
 218   { return this->elf_file_.section_flags(shndx); }
 219
 220   // Not used for dynobj.
 221   uint64_t
 222   do_section_entsize(unsigned int )
 223   { gold_unreachable(); }
 224
 225   // Return section address.
 226   uint64_t
 227   do_section_address(unsigned int shndx)
 228   { return this->elf_file_.section_addr(shndx); }
 229
 230   // Return section type.
 231   unsigned int
 232   do_section_type(unsigned int shndx)
 233   { return this->elf_file_.section_type(shndx); }
 234
 235   // Return the section link field.
 236   unsigned int
 237   do_section_link(unsigned int shndx)
 238   { return this->elf_file_.section_link(shndx); }
 239
 240   // Return the section link field.
 241   unsigned int
 242   do_section_info(unsigned int shndx)
 243   { return this->elf_file_.section_info(shndx); }
 244
 245   // Return the section alignment.
 246   uint64_t
 247   do_section_addralign(unsigned int shndx)
 248   { return this->elf_file_.section_addralign(shndx); }
 249
 250   // Return the Xindex structure to use.
 251   Xindex*
 252   do_initialize_xindex();
 253
 254   // Get symbol counts.
 255   void
 256   do_get_global_symbol_counts(const Symbol_table*, size_t*, size_t*) const;
 257
 258   // Get the global symbols.
 259   const Symbols*
 260   do_get_global_symbols() const
 261   { return this->symbols_; }
 262
 263  private:
 264   // For convenience.
 265   typedef Sized_dynobj<size, big_endian> This;
 266   static const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
 267   static const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
 268   static const int dyn_size = elfcpp::Elf_sizes<size>::dyn_size;
 269   typedef elfcpp::Shdr<size, big_endian> Shdr;
 270   typedef elfcpp::Dyn<size, big_endian> Dyn;
 271
 272   // Adjust a section index if necessary.
 273   unsigned int
 274   adjust_shndx(unsigned int shndx)
 275   {
 276     if (shndx >= elfcpp::SHN_LORESERVE)
 277       shndx += this->elf_file_.large_shndx_offset();
 278     return shndx;
 279   }
 280
 281   // Find the dynamic symbol table and the version sections, given the
 282   // section headers.
 283   void
 284   find_dynsym_sections(const unsigned char* pshdrs,
 285                        unsigned int* pversym_shndx,
 286                        unsigned int* pverdef_shndx,
 287                        unsigned int* pverneed_shndx,
 288                        unsigned int* pdynamic_shndx);
 289
 290   // Read the dynamic symbol section SHNDX.
 291   void
 292   read_dynsym_section(const unsigned char* pshdrs, unsigned int shndx,
 293                       elfcpp::SHT type, unsigned int link,
 294                       File_view** view, section_size_type* view_size,
 295                       unsigned int* view_info);
 296
 297   // Read the dynamic tags.
 298   void
 299   read_dynamic(const unsigned char* pshdrs, unsigned int dynamic_shndx,
 300                unsigned int strtab_shndx, const unsigned char* strtabu,
 301                off_t strtab_size);
 302
 303   // Mapping from version number to version name.
 304   typedef std::vector<const char*> Version_map;
 305
 306   // Create the version map.
 307   void
 308   make_version_map(Read_symbols_data* sd, Version_map*) const;
 309
 310   // Add version definitions to the version map.
 311   void
 312   make_verdef_map(Read_symbols_data* sd, Version_map*) const;
 313
 314   // Add version references to the version map.
 315   void
 316   make_verneed_map(Read_symbols_data* sd, Version_map*) const;
 317
 318   // Add an entry to the version map.
 319   void
 320   set_version_map(Version_map*, unsigned int ndx, const char* name) const;
 321
 322   // General access to the ELF file.
 323   elfcpp::Elf_file<size, big_endian, Object> elf_file_;
 324   // The section index of the dynamic symbol table.
 325   unsigned int dynsym_shndx_;
 326   // The entries in the symbol table for the symbols.  We only keep
 327   // this if we need it to print symbol information.
 328   Symbols* symbols_;
 329   // Number of defined symbols.
 330   size_t defined_count_;
 331 };
 332
 333 // A base class for Verdef and Verneed_version which just handles the
 334 // version index which will be stored in the SHT_GNU_versym section.
 335
 336 class Version_base
 337 {
 338  public:
 339   Version_base()
 340     : index_(-1U)
 341   { }
 342
 343   virtual
 344   ~Version_base()
 345   { }
 346
 347   // Return the version index.
 348   unsigned int
 349   index() const
 350   {
 351     gold_assert(this->index_ != -1U);
 352     return this->index_;
 353   }
 354
 355   // Set the version index.
 356   void
 357   set_index(unsigned int index)
 358   {
 359     gold_assert(this->index_ == -1U);
 360     this->index_ = index;
 361   }
 362
 363   // Clear the weak flag in a version definition.
 364   virtual void
 365   clear_weak() = 0;
 366
 367  private:
 368   Version_base(const Version_base&);
 369   Version_base& operator=(const Version_base&);
 370
 371   // The index of the version definition or reference.
 372   unsigned int index_;
 373 };
 374
 375 // This class handles a version being defined in the file we are
 376 // generating.
 377
 378 class Verdef : public Version_base
 379 {
 380  public:
 381   Verdef(const char* name, const std::vector<std::string>& deps,
 382          bool is_base, bool is_weak, bool is_info, bool is_symbol_created)
 383     : name_(name), deps_(deps), is_base_(is_base), is_weak_(is_weak),
 384       is_info_(is_info), is_symbol_created_(is_symbol_created)
 385   { }
 386
 387   // Return the version name.
 388   const char*
 389   name() const
 390   { return this->name_; }
 391
 392   // Return the number of dependencies.
 393   unsigned int
 394   count_dependencies() const
 395   { return this->deps_.size(); }
 396
 397   // Add a dependency to this version.  The NAME should be
 398   // canonicalized in the dynamic Stringpool.
 399   void
 400   add_dependency(const char* name)
 401   { this->deps_.push_back(name); }
 402
 403   // Return whether this definition is weak.
 404   bool
 405   is_weak() const
 406   { return this->is_weak_; }
 407
 408   // Clear the weak flag.
 409   void
 410   clear_weak()
 411   { this->is_weak_ = false; }
 412
 413   // Return whether this definition is informational.
 414   bool
 415   is_info() const
 416   { return this->is_info_; }
 417
 418   // Return whether a version symbol has been created for this
 419   // definition.
 420   bool
 421   is_symbol_created() const
 422   { return this->is_symbol_created_; }
 423
 424   // Write contents to buffer.
 425   template<int size, bool big_endian>
 426   unsigned char*
 427   write(const Stringpool*, bool is_last, unsigned char*) const;
 428
 429  private:
 430   Verdef(const Verdef&);
 431   Verdef& operator=(const Verdef&);
 432
 433   // The type of the list of version dependencies.  Each dependency
 434   // should be canonicalized in the dynamic Stringpool.
 435   typedef std::vector<std::string> Deps;
 436
 437   // The name of this version.  This should be canonicalized in the
 438   // dynamic Stringpool.
 439   const char* name_;
 440   // A list of other versions which this version depends upon.
 441   Deps deps_;
 442   // Whether this is the base version.
 443   bool is_base_;
 444   // Whether this version is weak.
 445   bool is_weak_;
 446   // Whether this version is informational.
 447   bool is_info_;
 448   // Whether a version symbol has been created.
 449   bool is_symbol_created_;
 450 };
 451
 452 // A referened version.  This will be associated with a filename by
 453 // Verneed.
 454
 455 class Verneed_version : public Version_base
 456 {
 457  public:
 458   Verneed_version(const char* version)
 459     : version_(version)
 460   { }
 461
 462   // Return the version name.
 463   const char*
 464   version() const
 465   { return this->version_; }
 466
 467   // Clear the weak flag.  This is invalid for a reference.
 468   void
 469   clear_weak()
 470   { gold_unreachable(); }
 471
 472  private:
 473   Verneed_version(const Verneed_version&);
 474   Verneed_version& operator=(const Verneed_version&);
 475
 476   const char* version_;
 477 };
 478
 479 // Version references in a single dynamic object.
 480
 481 class Verneed
 482 {
 483  public:
 484   Verneed(const char* filename)
 485     : filename_(filename), need_versions_()
 486   { }
 487
 488   ~Verneed();
 489
 490   // Return the file name.
 491   const char*
 492   filename() const
 493   { return this->filename_; }
 494
 495   // Return the number of versions.
 496   unsigned int
 497   count_versions() const
 498   { return this->need_versions_.size(); }
 499
 500   // Add a version name.  The name should be canonicalized in the
 501   // dynamic Stringpool.  If the name is already present, this does
 502   // nothing.
 503   Verneed_version*
 504   add_name(const char* name);
 505
 506   // Set the version indexes, starting at INDEX.  Return the updated
 507   // INDEX.
 508   unsigned int
 509   finalize(unsigned int index);
 510
 511   // Write contents to buffer.
 512   template<int size, bool big_endian>
 513   unsigned char*
 514   write(const Stringpool*, bool is_last, unsigned char*) const;
 515
 516  private:
 517   Verneed(const Verneed&);
 518   Verneed& operator=(const Verneed&);
 519
 520   // The type of the list of version names.  Each name should be
 521   // canonicalized in the dynamic Stringpool.
 522   typedef std::vector<Verneed_version*> Need_versions;
 523
 524   // The filename of the dynamic object.  This should be
 525   // canonicalized in the dynamic Stringpool.
 526   const char* filename_;
 527   // The list of version names.
 528   Need_versions need_versions_;
 529 };
 530
 531 // This class handles version definitions and references which go into
 532 // the output file.
 533
 534 class Versions
 535 {
 536  public:
 537   Versions(const Version_script_info&, Stringpool*);
 538
 539   ~Versions();
 540
 541   // SYM is going into the dynamic symbol table and has a version.
 542   // Record the appropriate version information.
 543   void
 544   record_version(const Symbol_table* symtab, Stringpool*, const Symbol* sym);
 545
 546   // Set the version indexes.  DYNSYM_INDEX is the index we should use
 547   // for the next dynamic symbol.  We add new dynamic symbols to SYMS
 548   // and return an updated DYNSYM_INDEX.
 549   unsigned int
 550   finalize(Symbol_table* symtab, unsigned int dynsym_index,
 551            std::vector<Symbol*>* syms);
 552
 553   // Return whether there are any version definitions.
 554   bool
 555   any_defs() const
 556   { return !this->defs_.empty(); }
 557
 558   // Return whether there are any version references.
 559   bool
 560   any_needs() const
 561   { return !this->needs_.empty(); }
 562
 563   // Build an allocated buffer holding the contents of the symbol
 564   // version section (.gnu.version).
 565   template<int size, bool big_endian>
 566   void
 567   symbol_section_contents(const Symbol_table*, const Stringpool*,
 568                           unsigned int local_symcount,
 569                           const std::vector<Symbol*>& syms,
 570                           unsigned char**, unsigned int*) const;
 571
 572   // Build an allocated buffer holding the contents of the version
 573   // definition section (.gnu.version_d).
 574   template<int size, bool big_endian>
 575   void
 576   def_section_contents(const Stringpool*, unsigned char**,
 577                        unsigned int* psize, unsigned int* pentries) const;
 578
 579   // Build an allocated buffer holding the contents of the version
 580   // reference section (.gnu.version_r).
 581   template<int size, bool big_endian>
 582   void
 583   need_section_contents(const Stringpool*, unsigned char**,
 584                         unsigned int* psize, unsigned int* pentries) const;
 585
 586   const Version_script_info&
 587   version_script() const
 588   { return this->version_script_; }
 589
 590  private:
 591   Versions(const Versions&);
 592   Versions& operator=(const Versions&);
 593
 594   // The type of the list of version definitions.
 595   typedef std::vector<Verdef*> Defs;
 596
 597   // The type of the list of version references.
 598   typedef std::vector<Verneed*> Needs;
 599
 600   // Handle a symbol SYM defined with version VERSION.
 601   void
 602   add_def(Stringpool*, const Symbol* sym, const char* version,
 603           Stringpool::Key);
 604
 605   // Add a reference to version NAME in file FILENAME.
 606   void
 607   add_need(Stringpool*, const char* filename, const char* name,
 608            Stringpool::Key);
 609
 610   // Get the dynamic object to use for SYM.
 611   Dynobj*
 612   get_dynobj_for_sym(const Symbol_table*, const Symbol* sym) const;
 613
 614   // Return the version index to use for SYM.
 615   unsigned int
 616   version_index(const Symbol_table*, const Stringpool*,
 617                 const Symbol* sym) const;
 618
 619   // Define the base version of a shared library.
 620   void
 621   define_base_version(Stringpool* dynpool);
 622
 623   // We keep a hash table mapping canonicalized name/version pairs to
 624   // a version base.
 625   typedef std::pair<Stringpool::Key, Stringpool::Key> Key;
 626
 627   struct Version_table_hash
 628   {
 629     size_t
 630     operator()(const Key& k) const
 631     { return k.first + k.second; }
 632   };
 633
 634   struct Version_table_eq
 635   {
 636     bool
 637     operator()(const Key& k1, const Key& k2) const
 638     { return k1.first == k2.first && k1.second == k2.second; }
 639   };
 640
 641   typedef Unordered_map<Key, Version_base*, Version_table_hash,
 642                         Version_table_eq> Version_table;
 643
 644   // The version definitions.
 645   Defs defs_;
 646   // The version references.
 647   Needs needs_;
 648   // The mapping from a canonicalized version/filename pair to a
 649   // version index.  The filename may be NULL.
 650   Version_table version_table_;
 651   // Whether the version indexes have been set.
 652   bool is_finalized_;
 653   // Contents of --version-script, if passed, or NULL.
 654   const Version_script_info& version_script_;
 655   // Whether we need to insert a base version.  This is only used for
 656   // shared libraries and is cleared when the base version is defined.
 657   bool needs_base_version_;
 658 };
 659
 660 } // End namespace gold.
 661
 662 #endif // !defined(GOLD_DYNOBJ_H)