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
  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   Sized_dynobj(const std::string& name, Input_file* input_file, off_t offset,
 160                const typename elfcpp::Ehdr<size, big_endian>&);
 161
 162   // Set up the object file based on the ELF header.
 163   void
 164   setup(const typename elfcpp::Ehdr<size, big_endian>&);
 165
 166   // Read the symbols.
 167   void
 168   do_read_symbols(Read_symbols_data*);
 169
 170   // Lay out the input sections.
 171   void
 172   do_layout(Symbol_table*, Layout*, Read_symbols_data*);
 173
 174   // Add the symbols to the symbol table.
 175   void
 176   do_add_symbols(Symbol_table*, Read_symbols_data*);
 177
 178   // Get the name of a section.
 179   std::string
 180   do_section_name(unsigned int shndx)
 181   { return this->elf_file_.section_name(shndx); }
 182
 183   // Return a view of the contents of a section.  Set *PLEN to the
 184   // size.
 185   Object::Location
 186   do_section_contents(unsigned int shndx)
 187   { return this->elf_file_.section_contents(shndx); }
 188
 189   // Return section flags.
 190   uint64_t
 191   do_section_flags(unsigned int shndx)
 192   { return this->elf_file_.section_flags(shndx); }
 193
 194   // Return section type.
 195   unsigned int
 196   do_section_type(unsigned int shndx)
 197   { return this->elf_file_.section_type(shndx); }
 198
 199   // Return the section link field.
 200   unsigned int
 201   do_section_link(unsigned int shndx)
 202   { return this->elf_file_.section_link(shndx); }
 203
 204   // Return the section link field.
 205   unsigned int
 206   do_section_info(unsigned int shndx)
 207   { return this->elf_file_.section_info(shndx); }
 208
 209  private:
 210   // For convenience.
 211   typedef Sized_dynobj<size, big_endian> This;
 212   static const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
 213   static const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
 214   static const int dyn_size = elfcpp::Elf_sizes<size>::dyn_size;
 215   typedef elfcpp::Shdr<size, big_endian> Shdr;
 216   typedef elfcpp::Dyn<size, big_endian> Dyn;
 217
 218   // Find the dynamic symbol table and the version sections, given the
 219   // section headers.
 220   void
 221   find_dynsym_sections(const unsigned char* pshdrs,
 222                        unsigned int* pdynshm_shndx,
 223                        unsigned int* pversym_shndx,
 224                        unsigned int* pverdef_shndx,
 225                        unsigned int* pverneed_shndx,
 226                        unsigned int* pdynamic_shndx);
 227
 228   // Read the dynamic symbol section SHNDX.
 229   void
 230   read_dynsym_section(const unsigned char* pshdrs, unsigned int shndx,
 231                       elfcpp::SHT type, unsigned int link,
 232                       File_view** view, section_size_type* view_size,
 233                       unsigned int* view_info);
 234
 235   // Read the dynamic tags.
 236   void
 237   read_dynamic(const unsigned char* pshdrs, unsigned int dynamic_shndx,
 238                unsigned int strtab_shndx, const unsigned char* strtabu,
 239                off_t strtab_size);
 240
 241   // Mapping from version number to version name.
 242   typedef std::vector<const char*> Version_map;
 243
 244   // Create the version map.
 245   void
 246   make_version_map(Read_symbols_data* sd, Version_map*) const;
 247
 248   // Add version definitions to the version map.
 249   void
 250   make_verdef_map(Read_symbols_data* sd, Version_map*) const;
 251
 252   // Add version references to the version map.
 253   void
 254   make_verneed_map(Read_symbols_data* sd, Version_map*) const;
 255
 256   // Add an entry to the version map.
 257   void
 258   set_version_map(Version_map*, unsigned int ndx, const char* name) const;
 259
 260   // General access to the ELF file.
 261   elfcpp::Elf_file<size, big_endian, Object> elf_file_;
 262 };
 263
 264 // A base class for Verdef and Verneed_version which just handles the
 265 // version index which will be stored in the SHT_GNU_versym section.
 266
 267 class Version_base
 268 {
 269  public:
 270   Version_base()
 271     : index_(-1U)
 272   { }
 273
 274   virtual
 275   ~Version_base()
 276   { }
 277
 278   // Return the version index.
 279   unsigned int
 280   index() const
 281   {
 282     gold_assert(this->index_ != -1U);
 283     return this->index_;
 284   }
 285
 286   // Set the version index.
 287   void
 288   set_index(unsigned int index)
 289   {
 290     gold_assert(this->index_ == -1U);
 291     this->index_ = index;
 292   }
 293
 294   // Clear the weak flag in a version definition.
 295   virtual void
 296   clear_weak() = 0;
 297
 298  private:
 299   Version_base(const Version_base&);
 300   Version_base& operator=(const Version_base&);
 301
 302   // The index of the version definition or reference.
 303   unsigned int index_;
 304 };
 305
 306 // This class handles a version being defined in the file we are
 307 // generating.
 308
 309 class Verdef : public Version_base
 310 {
 311  public:
 312   Verdef(const char* name, bool is_base, bool is_weak, bool is_symbol_created)
 313     : name_(name), deps_(), is_base_(is_base), is_weak_(is_weak),
 314       is_symbol_created_(is_symbol_created)
 315   { }
 316
 317   // Return the version name.
 318   const char*
 319   name() const
 320   { return this->name_; }
 321
 322   // Return the number of dependencies.
 323   unsigned int
 324   count_dependencies() const
 325   { return this->deps_.size(); }
 326
 327   // Add a dependency to this version.  The NAME should be
 328   // canonicalized in the dynamic Stringpool.
 329   void
 330   add_dependency(const char* name)
 331   { this->deps_.push_back(name); }
 332
 333   // Return whether this definition is weak.
 334   bool
 335   is_weak() const
 336   { return this->is_weak_; }
 337
 338   // Clear the weak flag.
 339   void
 340   clear_weak()
 341   { this->is_weak_ = false; }
 342
 343   // Return whether a version symbol has been created for this
 344   // definition.
 345   bool
 346   is_symbol_created() const
 347   { return this->is_symbol_created_; }
 348
 349   // Write contents to buffer.
 350   template<int size, bool big_endian>
 351   unsigned char*
 352   write(const Stringpool*, bool is_last, unsigned char*
 353         ACCEPT_SIZE_ENDIAN) const;
 354
 355  private:
 356   Verdef(const Verdef&);
 357   Verdef& operator=(const Verdef&);
 358
 359   // The type of the list of version dependencies.  Each dependency
 360   // should be canonicalized in the dynamic Stringpool.
 361   typedef std::vector<const char*> Deps;
 362
 363   // The name of this version.  This should be canonicalized in the
 364   // dynamic Stringpool.
 365   const char* name_;
 366   // A list of other versions which this version depends upon.
 367   Deps deps_;
 368   // Whether this is the base version.
 369   bool is_base_;
 370   // Whether this version is weak.
 371   bool is_weak_;
 372   // Whether a version symbol has been created.
 373   bool is_symbol_created_;
 374 };
 375
 376 // A referened version.  This will be associated with a filename by
 377 // Verneed.
 378
 379 class Verneed_version : public Version_base
 380 {
 381  public:
 382   Verneed_version(const char* version)
 383     : version_(version)
 384   { }
 385
 386   // Return the version name.
 387   const char*
 388   version() const
 389   { return this->version_; }
 390
 391   // Clear the weak flag.  This is invalid for a reference.
 392   void
 393   clear_weak()
 394   { gold_unreachable(); }
 395
 396  private:
 397   Verneed_version(const Verneed_version&);
 398   Verneed_version& operator=(const Verneed_version&);
 399
 400   const char* version_;
 401 };
 402
 403 // Version references in a single dynamic object.
 404
 405 class Verneed
 406 {
 407  public:
 408   Verneed(const char* filename)
 409     : filename_(filename), need_versions_()
 410   { }
 411
 412   ~Verneed();
 413
 414   // Return the file name.
 415   const char*
 416   filename() const
 417   { return this->filename_; }
 418
 419   // Return the number of versions.
 420   unsigned int
 421   count_versions() const
 422   { return this->need_versions_.size(); }
 423
 424   // Add a version name.  The name should be canonicalized in the
 425   // dynamic Stringpool.  If the name is already present, this does
 426   // nothing.
 427   Verneed_version*
 428   add_name(const char* name);
 429
 430   // Set the version indexes, starting at INDEX.  Return the updated
 431   // INDEX.
 432   unsigned int
 433   finalize(unsigned int index);
 434
 435   // Write contents to buffer.
 436   template<int size, bool big_endian>
 437   unsigned char*
 438   write(const Stringpool*, bool is_last, unsigned char*
 439         ACCEPT_SIZE_ENDIAN) const;
 440
 441  private:
 442   Verneed(const Verneed&);
 443   Verneed& operator=(const Verneed&);
 444
 445   // The type of the list of version names.  Each name should be
 446   // canonicalized in the dynamic Stringpool.
 447   typedef std::vector<Verneed_version*> Need_versions;
 448
 449   // The filename of the dynamic object.  This should be
 450   // canonicalized in the dynamic Stringpool.
 451   const char* filename_;
 452   // The list of version names.
 453   Need_versions need_versions_;
 454 };
 455
 456 // This class handles version definitions and references which go into
 457 // the output file.
 458
 459 class Versions
 460 {
 461  public:
 462   Versions()
 463     : defs_(), needs_(), version_table_(), is_finalized_(false)
 464   { }
 465
 466   ~Versions();
 467
 468   // SYM is going into the dynamic symbol table and has a version.
 469   // Record the appropriate version information.
 470   void
 471   record_version(const Symbol_table* symtab, Stringpool*, const Symbol* sym);
 472
 473   // Set the version indexes.  DYNSYM_INDEX is the index we should use
 474   // for the next dynamic symbol.  We add new dynamic symbols to SYMS
 475   // and return an updated DYNSYM_INDEX.
 476   unsigned int
 477   finalize(const Target*, Symbol_table* symtab, unsigned int dynsym_index,
 478            std::vector<Symbol*>* syms);
 479
 480   // Return whether there are any version definitions.
 481   bool
 482   any_defs() const
 483   { return !this->defs_.empty(); }
 484
 485   // Return whether there are any version references.
 486   bool
 487   any_needs() const
 488   { return !this->needs_.empty(); }
 489
 490   // Build an allocated buffer holding the contents of the symbol
 491   // version section (.gnu.version).
 492   template<int size, bool big_endian>
 493   void
 494   symbol_section_contents(const Symbol_table*, const Stringpool*,
 495                           unsigned int local_symcount,
 496                           const std::vector<Symbol*>& syms,
 497                           unsigned char**, unsigned int*
 498                           ACCEPT_SIZE_ENDIAN) const;
 499
 500   // Build an allocated buffer holding the contents of the version
 501   // definition section (.gnu.version_d).
 502   template<int size, bool big_endian>
 503   void
 504   def_section_contents(const Stringpool*, unsigned char**,
 505                        unsigned int* psize, unsigned int* pentries
 506                        ACCEPT_SIZE_ENDIAN) const;
 507
 508   // Build an allocated buffer holding the contents of the version
 509   // reference section (.gnu.version_r).
 510   template<int size, bool big_endian>
 511   void
 512   need_section_contents(const Stringpool*, unsigned char**,
 513                         unsigned int* psize, unsigned int* pentries
 514                         ACCEPT_SIZE_ENDIAN) const;
 515
 516  private:
 517   // The type of the list of version definitions.
 518   typedef std::vector<Verdef*> Defs;
 519
 520   // The type of the list of version references.
 521   typedef std::vector<Verneed*> Needs;
 522
 523   // Handle a symbol SYM defined with version VERSION.
 524   void
 525   add_def(const Symbol* sym, const char* version, Stringpool::Key);
 526
 527   // Add a reference to version NAME in file FILENAME.
 528   void
 529   add_need(Stringpool*, const char* filename, const char* name,
 530            Stringpool::Key);
 531
 532   // Get the dynamic object to use for SYM.
 533   Dynobj*
 534   get_dynobj_for_sym(const Symbol_table*, const Symbol* sym) const;
 535
 536   // Return the version index to use for SYM.
 537   unsigned int
 538   version_index(const Symbol_table*, const Stringpool*,
 539                 const Symbol* sym) const;
 540
 541   // We keep a hash table mapping canonicalized name/version pairs to
 542   // a version base.
 543   typedef std::pair<Stringpool::Key, Stringpool::Key> Key;
 544
 545   struct Version_table_hash
 546   {
 547     size_t
 548     operator()(const Key& k) const
 549     { return k.first + k.second; }
 550   };
 551
 552   struct Version_table_eq
 553   {
 554     bool
 555     operator()(const Key& k1, const Key& k2) const
 556     { return k1.first == k2.first && k1.second == k2.second; }
 557   };
 558
 559   typedef Unordered_map<Key, Version_base*, Version_table_hash,
 560                         Version_table_eq> Version_table;
 561
 562   // The version definitions.
 563   Defs defs_;
 564   // The version references.
 565   Needs needs_;
 566   // The mapping from a canonicalized version/filename pair to a
 567   // version index.  The filename may be NULL.
 568   Version_table version_table_;
 569   // Whether the version indexes have been set.
 570   bool is_finalized_;
 571 };
 572
 573 } // End namespace gold.
 574
 575 #endif // !defined(GOLD_DYNOBJ_H)