gold/dynobj.h

   1 // dynobj.h -- dynamic object support for gold   -*- C++ -*-
   2
   3 // Copyright 2006, 2007, 2008 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   // Get the size of a section.
 181   uint64_t
 182   do_section_size(unsigned int shndx)
 183   { return this->elf_file_.section_size(shndx); }
 184
 185   // Get the name of a section.
 186   std::string
 187   do_section_name(unsigned int shndx)
 188   { return this->elf_file_.section_name(shndx); }
 189
 190   // Return a view of the contents of a section.  Set *PLEN to the
 191   // size.
 192   Object::Location
 193   do_section_contents(unsigned int shndx)
 194   { return this->elf_file_.section_contents(shndx); }
 195
 196   // Return section flags.
 197   uint64_t
 198   do_section_flags(unsigned int shndx)
 199   { return this->elf_file_.section_flags(shndx); }
 200
 201   // Not used for dynobj.
 202   uint64_t
 203   do_section_entsize(unsigned int )
 204   { gold_unreachable(); }
 205
 206   // Return section address.
 207   uint64_t
 208   do_section_address(unsigned int shndx)
 209   { return this->elf_file_.section_addr(shndx); }
 210
 211   // Return section type.
 212   unsigned int
 213   do_section_type(unsigned int shndx)
 214   { return this->elf_file_.section_type(shndx); }
 215
 216   // Return the section link field.
 217   unsigned int
 218   do_section_link(unsigned int shndx)
 219   { return this->elf_file_.section_link(shndx); }
 220
 221   // Return the section link field.
 222   unsigned int
 223   do_section_info(unsigned int shndx)
 224   { return this->elf_file_.section_info(shndx); }
 225
 226   // Return the section alignment.
 227   uint64_t
 228   do_section_addralign(unsigned int shndx)
 229   { return this->elf_file_.section_addralign(shndx); }
 230
 231   // Return the Xindex structure to use.
 232   Xindex*
 233   do_initialize_xindex();
 234
 235   // Get symbol counts.
 236   void
 237   do_get_global_symbol_counts(const Symbol_table*, size_t*, size_t*) const;
 238
 239  private:
 240   // For convenience.
 241   typedef Sized_dynobj<size, big_endian> This;
 242   static const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
 243   static const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
 244   static const int dyn_size = elfcpp::Elf_sizes<size>::dyn_size;
 245   typedef elfcpp::Shdr<size, big_endian> Shdr;
 246   typedef elfcpp::Dyn<size, big_endian> Dyn;
 247
 248   // Adjust a section index if necessary.
 249   unsigned int
 250   adjust_shndx(unsigned int shndx)
 251   {
 252     if (shndx >= elfcpp::SHN_LORESERVE)
 253       shndx += this->elf_file_.large_shndx_offset();
 254     return shndx;
 255   }
 256
 257   // Find the dynamic symbol table and the version sections, given the
 258   // section headers.
 259   void
 260   find_dynsym_sections(const unsigned char* pshdrs,
 261                        unsigned int* pversym_shndx,
 262                        unsigned int* pverdef_shndx,
 263                        unsigned int* pverneed_shndx,
 264                        unsigned int* pdynamic_shndx);
 265
 266   // Read the dynamic symbol section SHNDX.
 267   void
 268   read_dynsym_section(const unsigned char* pshdrs, unsigned int shndx,
 269                       elfcpp::SHT type, unsigned int link,
 270                       File_view** view, section_size_type* view_size,
 271                       unsigned int* view_info);
 272
 273   // Read the dynamic tags.
 274   void
 275   read_dynamic(const unsigned char* pshdrs, unsigned int dynamic_shndx,
 276                unsigned int strtab_shndx, const unsigned char* strtabu,
 277                off_t strtab_size);
 278
 279   // Mapping from version number to version name.
 280   typedef std::vector<const char*> Version_map;
 281
 282   // Create the version map.
 283   void
 284   make_version_map(Read_symbols_data* sd, Version_map*) const;
 285
 286   // Add version definitions to the version map.
 287   void
 288   make_verdef_map(Read_symbols_data* sd, Version_map*) const;
 289
 290   // Add version references to the version map.
 291   void
 292   make_verneed_map(Read_symbols_data* sd, Version_map*) const;
 293
 294   // Add an entry to the version map.
 295   void
 296   set_version_map(Version_map*, unsigned int ndx, const char* name) const;
 297
 298   // General access to the ELF file.
 299   elfcpp::Elf_file<size, big_endian, Object> elf_file_;
 300   // The section index of the dynamic symbol table.
 301   unsigned int dynsym_shndx_;
 302   // The entries in the symbol table for the symbols.  We only keep
 303   // this if we need it to print symbol information.
 304   Symbols* symbols_;
 305   // Number of defined symbols.
 306   size_t defined_count_;
 307 };
 308
 309 // A base class for Verdef and Verneed_version which just handles the
 310 // version index which will be stored in the SHT_GNU_versym section.
 311
 312 class Version_base
 313 {
 314  public:
 315   Version_base()
 316     : index_(-1U)
 317   { }
 318
 319   virtual
 320   ~Version_base()
 321   { }
 322
 323   // Return the version index.
 324   unsigned int
 325   index() const
 326   {
 327     gold_assert(this->index_ != -1U);
 328     return this->index_;
 329   }
 330
 331   // Set the version index.
 332   void
 333   set_index(unsigned int vindex)
 334   {
 335     gold_assert(this->index_ == -1U);
 336     this->index_ = vindex;
 337   }
 338
 339   // Clear the weak flag in a version definition.
 340   virtual void
 341   clear_weak() = 0;
 342
 343  private:
 344   Version_base(const Version_base&);
 345   Version_base& operator=(const Version_base&);
 346
 347   // The index of the version definition or reference.
 348   unsigned int index_;
 349 };
 350
 351 // This class handles a version being defined in the file we are
 352 // generating.
 353
 354 class Verdef : public Version_base
 355 {
 356  public:
 357   Verdef(const char* vname, const std::vector<std::string>& deps,
 358          bool is_base, bool vis_weak, bool vis_symbol_created)
 359     : name_(vname), deps_(deps), is_base_(is_base), is_weak_(vis_weak),
 360       is_symbol_created_(vis_symbol_created)
 361   { }
 362
 363   // Return the version name.
 364   const char*
 365   name() const
 366   { return this->name_; }
 367
 368   // Return the number of dependencies.
 369   unsigned int
 370   count_dependencies() const
 371   { return this->deps_.size(); }
 372
 373   // Add a dependency to this version.  The NAME should be
 374   // canonicalized in the dynamic Stringpool.
 375   void
 376   add_dependency(const char* dname)
 377   { this->deps_.push_back(dname); }
 378
 379   // Return whether this definition is weak.
 380   bool
 381   is_weak() const
 382   { return this->is_weak_; }
 383
 384   // Clear the weak flag.
 385   void
 386   clear_weak()
 387   { this->is_weak_ = false; }
 388
 389   // Return whether a version symbol has been created for this
 390   // definition.
 391   bool
 392   is_symbol_created() const
 393   { return this->is_symbol_created_; }
 394
 395   // Write contents to buffer.
 396   template<int size, bool big_endian>
 397   unsigned char*
 398   write(const Stringpool*, bool is_last, unsigned char*) const;
 399
 400  private:
 401   Verdef(const Verdef&);
 402   Verdef& operator=(const Verdef&);
 403
 404   // The type of the list of version dependencies.  Each dependency
 405   // should be canonicalized in the dynamic Stringpool.
 406   typedef std::vector<std::string> Deps;
 407
 408   // The name of this version.  This should be canonicalized in the
 409   // dynamic Stringpool.
 410   const char* name_;
 411   // A list of other versions which this version depends upon.
 412   Deps deps_;
 413   // Whether this is the base version.
 414   bool is_base_;
 415   // Whether this version is weak.
 416   bool is_weak_;
 417   // Whether a version symbol has been created.
 418   bool is_symbol_created_;
 419 };
 420
 421 // A referened version.  This will be associated with a filename by
 422 // Verneed.
 423
 424 class Verneed_version : public Version_base
 425 {
 426  public:
 427   Verneed_version(const char* ver)
 428     : version_(ver)
 429   { }
 430
 431   // Return the version name.
 432   const char*
 433   version() const
 434   { return this->version_; }
 435
 436   // Clear the weak flag.  This is invalid for a reference.
 437   void
 438   clear_weak()
 439   { gold_unreachable(); }
 440
 441  private:
 442   Verneed_version(const Verneed_version&);
 443   Verneed_version& operator=(const Verneed_version&);
 444
 445   const char* version_;
 446 };
 447
 448 // Version references in a single dynamic object.
 449
 450 class Verneed
 451 {
 452  public:
 453   Verneed(const char* fname)
 454     : filename_(fname), need_versions_()
 455   { }
 456
 457   ~Verneed();
 458
 459   // Return the file name.
 460   const char*
 461   filename() const
 462   { return this->filename_; }
 463
 464   // Return the number of versions.
 465   unsigned int
 466   count_versions() const
 467   { return this->need_versions_.size(); }
 468
 469   // Add a version name.  The name should be canonicalized in the
 470   // dynamic Stringpool.  If the name is already present, this does
 471   // nothing.
 472   Verneed_version*
 473   add_name(const char* name);
 474
 475   // Set the version indexes, starting at INDEX.  Return the updated
 476   // INDEX.
 477   unsigned int
 478   finalize(unsigned int index);
 479
 480   // Write contents to buffer.
 481   template<int size, bool big_endian>
 482   unsigned char*
 483   write(const Stringpool*, bool is_last, unsigned char*) const;
 484
 485  private:
 486   Verneed(const Verneed&);
 487   Verneed& operator=(const Verneed&);
 488
 489   // The type of the list of version names.  Each name should be
 490   // canonicalized in the dynamic Stringpool.
 491   typedef std::vector<Verneed_version*> Need_versions;
 492
 493   // The filename of the dynamic object.  This should be
 494   // canonicalized in the dynamic Stringpool.
 495   const char* filename_;
 496   // The list of version names.
 497   Need_versions need_versions_;
 498 };
 499
 500 // This class handles version definitions and references which go into
 501 // the output file.
 502
 503 class Versions
 504 {
 505  public:
 506   Versions(const Version_script_info&, Stringpool*);
 507
 508   ~Versions();
 509
 510   // SYM is going into the dynamic symbol table and has a version.
 511   // Record the appropriate version information.
 512   void
 513   record_version(const Symbol_table* symtab, Stringpool*, const Symbol* sym);
 514
 515   // Set the version indexes.  DYNSYM_INDEX is the index we should use
 516   // for the next dynamic symbol.  We add new dynamic symbols to SYMS
 517   // and return an updated DYNSYM_INDEX.
 518   unsigned int
 519   finalize(Symbol_table* symtab, unsigned int dynsym_index,
 520            std::vector<Symbol*>* syms);
 521
 522   // Return whether there are any version definitions.
 523   bool
 524   any_defs() const
 525   { return !this->defs_.empty(); }
 526
 527   // Return whether there are any version references.
 528   bool
 529   any_needs() const
 530   { return !this->needs_.empty(); }
 531
 532   // Build an allocated buffer holding the contents of the symbol
 533   // version section (.gnu.version).
 534   template<int size, bool big_endian>
 535   void
 536   symbol_section_contents(const Symbol_table*, const Stringpool*,
 537                           unsigned int local_symcount,
 538                           const std::vector<Symbol*>& syms,
 539                           unsigned char**, unsigned int*) const;
 540
 541   // Build an allocated buffer holding the contents of the version
 542   // definition section (.gnu.version_d).
 543   template<int size, bool big_endian>
 544   void
 545   def_section_contents(const Stringpool*, unsigned char**,
 546                        unsigned int* psize, unsigned int* pentries) const;
 547
 548   // Build an allocated buffer holding the contents of the version
 549   // reference section (.gnu.version_r).
 550   template<int size, bool big_endian>
 551   void
 552   need_section_contents(const Stringpool*, unsigned char**,
 553                         unsigned int* psize, unsigned int* pentries) const;
 554
 555   const Version_script_info&
 556   version_script() const
 557   { return this->version_script_; }
 558
 559  private:
 560   Versions(const Versions&);
 561   Versions& operator=(const Versions&);
 562
 563   // The type of the list of version definitions.
 564   typedef std::vector<Verdef*> Defs;
 565
 566   // The type of the list of version references.
 567   typedef std::vector<Verneed*> Needs;
 568
 569   // Handle a symbol SYM defined with version VERSION.
 570   void
 571   add_def(const Symbol* sym, const char* version, Stringpool::Key);
 572
 573   // Add a reference to version NAME in file FILENAME.
 574   void
 575   add_need(Stringpool*, const char* filename, const char* name,
 576            Stringpool::Key);
 577
 578   // Get the dynamic object to use for SYM.
 579   Dynobj*
 580   get_dynobj_for_sym(const Symbol_table*, const Symbol* sym) const;
 581
 582   // Return the version index to use for SYM.
 583   unsigned int
 584   version_index(const Symbol_table*, const Stringpool*,
 585                 const Symbol* sym) const;
 586
 587   // Define the base version of a shared library.
 588   void
 589   define_base_version(Stringpool* dynpool);
 590
 591   // We keep a hash table mapping canonicalized name/version pairs to
 592   // a version base.
 593   typedef std::pair<Stringpool::Key, Stringpool::Key> Key;
 594
 595   struct Version_table_hash
 596   {
 597     size_t
 598     operator()(const Key& k) const
 599     { return k.first + k.second; }
 600   };
 601
 602   struct Version_table_eq
 603   {
 604     bool
 605     operator()(const Key& k1, const Key& k2) const
 606     { return k1.first == k2.first && k1.second == k2.second; }
 607   };
 608
 609   typedef Unordered_map<Key, Version_base*, Version_table_hash,
 610                         Version_table_eq> Version_table;
 611
 612   // The version definitions.
 613   Defs defs_;
 614   // The version references.
 615   Needs needs_;
 616   // The mapping from a canonicalized version/filename pair to a
 617   // version index.  The filename may be NULL.
 618   Version_table version_table_;
 619   // Whether the version indexes have been set.
 620   bool is_finalized_;
 621   // Contents of --version-script, if passed, or NULL.
 622   const Version_script_info& version_script_;
 623   // Whether we need to insert a base version.  This is only used for
 624   // shared libaries and is cleared when the base version is defined.
 625   bool needs_base_version_;
 626 };
 627
 628 } // End namespace gold.
 629
 630 #endif // !defined(GOLD_DYNOBJ_H)