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