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