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