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   Dynobj(const std::string& name, Input_file* input_file, off_t offset = 0);
  43
  44   // Return the name to use in a DT_NEEDED entry for this object.
  45   const char*
  46   soname() const;
  47
  48   // Compute the ELF hash code for a string.
  49   static uint32_t
  50   elf_hash(const char*);
  51
  52   // Create a standard ELF hash table, setting *PPHASH and *PHASHLEN.
  53   // DYNSYMS is the global dynamic symbols.  LOCAL_DYNSYM_COUNT is the
  54   // number of local dynamic symbols, which is the index of the first
  55   // dynamic gobal symbol.
  56   static void
  57   create_elf_hash_table(const std::vector<Symbol*>& dynsyms,
  58                         unsigned int local_dynsym_count,
  59                         unsigned char** pphash,
  60                         unsigned int* phashlen);
  61
  62   // Create a GNU hash table, setting *PPHASH and *PHASHLEN.  DYNSYMS
  63   // is the global dynamic symbols.  LOCAL_DYNSYM_COUNT is the number
  64   // of local dynamic symbols, which is the index of the first dynamic
  65   // gobal symbol.
  66   static void
  67   create_gnu_hash_table(const std::vector<Symbol*>& dynsyms,
  68                         unsigned int local_dynsym_count,
  69                         unsigned char** pphash, unsigned int* phashlen);
  70
  71  protected:
  72   // Set the DT_SONAME string.
  73   void
  74   set_soname_string(const char* s)
  75   { this->soname_.assign(s); }
  76
  77  private:
  78   // Compute the GNU hash code for a string.
  79   static uint32_t
  80   gnu_hash(const char*);
  81
  82   // Compute the number of hash buckets to use.
  83   static unsigned int
  84   compute_bucket_count(const std::vector<uint32_t>& hashcodes,
  85                        bool for_gnu_hash_table);
  86
  87   // Sized version of create_elf_hash_table.
  88   template<bool big_endian>
  89   static void
  90   sized_create_elf_hash_table(const std::vector<uint32_t>& bucket,
  91                               const std::vector<uint32_t>& chain,
  92                               unsigned char* phash,
  93                               unsigned int hashlen);
  94
  95   // Sized version of create_gnu_hash_table.
  96   template<int size, bool big_endian>
  97   static void
  98   sized_create_gnu_hash_table(const std::vector<Symbol*>& hashed_dynsyms,
  99                               const std::vector<uint32_t>& dynsym_hashvals,
 100                               unsigned int unhashed_dynsym_count,
 101                               unsigned char** pphash,
 102                               unsigned int* phashlen);
 103
 104   // The DT_SONAME name, if any.
 105   std::string soname_;
 106 };
 107
 108 // A dynamic object, size and endian specific version.
 109
 110 template<int size, bool big_endian>
 111 class Sized_dynobj : public Dynobj
 112 {
 113  public:
 114   Sized_dynobj(const std::string& name, Input_file* input_file, off_t offset,
 115                const typename elfcpp::Ehdr<size, big_endian>&);
 116
 117   // Set up the object file based on the ELF header.
 118   void
 119   setup(const typename elfcpp::Ehdr<size, big_endian>&);
 120
 121   // Read the symbols.
 122   void
 123   do_read_symbols(Read_symbols_data*);
 124
 125   // Lay out the input sections.
 126   void
 127   do_layout(Symbol_table*, Layout*, Read_symbols_data*);
 128
 129   // Add the symbols to the symbol table.
 130   void
 131   do_add_symbols(Symbol_table*, Read_symbols_data*);
 132
 133   // Get the name of a section.
 134   std::string
 135   do_section_name(unsigned int shndx)
 136   { return this->elf_file_.section_name(shndx); }
 137
 138   // Return a view of the contents of a section.  Set *PLEN to the
 139   // size.
 140   Object::Location
 141   do_section_contents(unsigned int shndx)
 142   { return this->elf_file_.section_contents(shndx); }
 143
 144   // Return section flags.
 145   uint64_t
 146   do_section_flags(unsigned int shndx)
 147   { return this->elf_file_.section_flags(shndx); }
 148
 149   // Return section type.
 150   unsigned int
 151   do_section_type(unsigned int shndx)
 152   { return this->elf_file_.section_type(shndx); }
 153
 154   // Return the section link field.
 155   unsigned int
 156   do_section_link(unsigned int shndx)
 157   { return this->elf_file_.section_link(shndx); }
 158
 159  private:
 160   // For convenience.
 161   typedef Sized_dynobj<size, big_endian> This;
 162   static const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
 163   static const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
 164   static const int dyn_size = elfcpp::Elf_sizes<size>::dyn_size;
 165   typedef elfcpp::Shdr<size, big_endian> Shdr;
 166   typedef elfcpp::Dyn<size, big_endian> Dyn;
 167
 168   // Find the dynamic symbol table and the version sections, given the
 169   // section headers.
 170   void
 171   find_dynsym_sections(const unsigned char* pshdrs,
 172                        unsigned int* pdynshm_shndx,
 173                        unsigned int* pversym_shndx,
 174                        unsigned int* pverdef_shndx,
 175                        unsigned int* pverneed_shndx,
 176                        unsigned int* pdynamic_shndx);
 177
 178   // Read the dynamic symbol section SHNDX.
 179   void
 180   read_dynsym_section(const unsigned char* pshdrs, unsigned int shndx,
 181                       elfcpp::SHT type, unsigned int link,
 182                       File_view** view, off_t* view_size,
 183                       unsigned int* view_info);
 184
 185   // Set the SONAME from the SHT_DYNAMIC section at DYNAMIC_SHNDX.
 186   // The STRTAB parameters may have the relevant string table.
 187   void
 188   set_soname(const unsigned char* pshdrs, unsigned int dynamic_shndx,
 189              unsigned int strtab_shndx, const unsigned char* strtabu,
 190              off_t strtab_size);
 191
 192   // Mapping from version number to version name.
 193   typedef std::vector<const char*> Version_map;
 194
 195   // Create the version map.
 196   void
 197   make_version_map(Read_symbols_data* sd, Version_map*) const;
 198
 199   // Add version definitions to the version map.
 200   void
 201   make_verdef_map(Read_symbols_data* sd, Version_map*) const;
 202
 203   // Add version references to the version map.
 204   void
 205   make_verneed_map(Read_symbols_data* sd, Version_map*) const;
 206
 207   // Add an entry to the version map.
 208   void
 209   set_version_map(Version_map*, unsigned int ndx, const char* name) const;
 210
 211   // General access to the ELF file.
 212   elfcpp::Elf_file<size, big_endian, Object> elf_file_;
 213 };
 214
 215 // A base class for Verdef and Verneed_version which just handles the
 216 // version index which will be stored in the SHT_GNU_versym section.
 217
 218 class Version_base
 219 {
 220  public:
 221   Version_base()
 222     : index_(-1U)
 223   { }
 224
 225   virtual
 226   ~Version_base()
 227   { }
 228
 229   // Return the version index.
 230   unsigned int
 231   index() const
 232   {
 233     gold_assert(this->index_ != -1U);
 234     return this->index_;
 235   }
 236
 237   // Set the version index.
 238   void
 239   set_index(unsigned int index)
 240   {
 241     gold_assert(this->index_ == -1U);
 242     this->index_ = index;
 243   }
 244
 245   // Clear the weak flag in a version definition.
 246   virtual void
 247   clear_weak() = 0;
 248
 249  private:
 250   Version_base(const Version_base&);
 251   Version_base& operator=(const Version_base&);
 252
 253   // The index of the version definition or reference.
 254   unsigned int index_;
 255 };
 256
 257 // This class handles a version being defined in the file we are
 258 // generating.
 259
 260 class Verdef : public Version_base
 261 {
 262  public:
 263   Verdef(const char* name, bool is_base, bool is_weak, bool is_symbol_created)
 264     : name_(name), deps_(), is_base_(is_base), is_weak_(is_weak),
 265       is_symbol_created_(is_symbol_created)
 266   { }
 267
 268   // Return the version name.
 269   const char*
 270   name() const
 271   { return this->name_; }
 272
 273   // Return the number of dependencies.
 274   unsigned int
 275   count_dependencies() const
 276   { return this->deps_.size(); }
 277
 278   // Add a dependency to this version.  The NAME should be
 279   // canonicalized in the dynamic Stringpool.
 280   void
 281   add_dependency(const char* name)
 282   { this->deps_.push_back(name); }
 283
 284   // Return whether this definition is weak.
 285   bool
 286   is_weak() const
 287   { return this->is_weak_; }
 288
 289   // Clear the weak flag.
 290   void
 291   clear_weak()
 292   { this->is_weak_ = false; }
 293
 294   // Return whether a version symbol has been created for this
 295   // definition.
 296   bool
 297   is_symbol_created() const
 298   { return this->is_symbol_created_; }
 299
 300   // Write contents to buffer.
 301   template<int size, bool big_endian>
 302   unsigned char*
 303   write(const Stringpool*, bool is_last, unsigned char*
 304         ACCEPT_SIZE_ENDIAN) const;
 305
 306  private:
 307   Verdef(const Verdef&);
 308   Verdef& operator=(const Verdef&);
 309
 310   // The type of the list of version dependencies.  Each dependency
 311   // should be canonicalized in the dynamic Stringpool.
 312   typedef std::vector<const char*> Deps;
 313
 314   // The name of this version.  This should be canonicalized in the
 315   // dynamic Stringpool.
 316   const char* name_;
 317   // A list of other versions which this version depends upon.
 318   Deps deps_;
 319   // Whether this is the base version.
 320   bool is_base_;
 321   // Whether this version is weak.
 322   bool is_weak_;
 323   // Whether a version symbol has been created.
 324   bool is_symbol_created_;
 325 };
 326
 327 // A referened version.  This will be associated with a filename by
 328 // Verneed.
 329
 330 class Verneed_version : public Version_base
 331 {
 332  public:
 333   Verneed_version(const char* version)
 334     : version_(version)
 335   { }
 336
 337   // Return the version name.
 338   const char*
 339   version() const
 340   { return this->version_; }
 341
 342   // Clear the weak flag.  This is invalid for a reference.
 343   void
 344   clear_weak()
 345   { gold_unreachable(); }
 346
 347  private:
 348   Verneed_version(const Verneed_version&);
 349   Verneed_version& operator=(const Verneed_version&);
 350
 351   const char* version_;
 352 };
 353
 354 // Version references in a single dynamic object.
 355
 356 class Verneed
 357 {
 358  public:
 359   Verneed(const char* filename)
 360     : filename_(filename), need_versions_()
 361   { }
 362
 363   ~Verneed();
 364
 365   // Return the file name.
 366   const char*
 367   filename() const
 368   { return this->filename_; }
 369
 370   // Return the number of versions.
 371   unsigned int
 372   count_versions() const
 373   { return this->need_versions_.size(); }
 374
 375   // Add a version name.  The name should be canonicalized in the
 376   // dynamic Stringpool.  If the name is already present, this does
 377   // nothing.
 378   Verneed_version*
 379   add_name(const char* name);
 380
 381   // Set the version indexes, starting at INDEX.  Return the updated
 382   // INDEX.
 383   unsigned int
 384   finalize(unsigned int index);
 385
 386   // Write contents to buffer.
 387   template<int size, bool big_endian>
 388   unsigned char*
 389   write(const Stringpool*, bool is_last, unsigned char*
 390         ACCEPT_SIZE_ENDIAN) const;
 391
 392  private:
 393   Verneed(const Verneed&);
 394   Verneed& operator=(const Verneed&);
 395
 396   // The type of the list of version names.  Each name should be
 397   // canonicalized in the dynamic Stringpool.
 398   typedef std::vector<Verneed_version*> Need_versions;
 399
 400   // The filename of the dynamic object.  This should be
 401   // canonicalized in the dynamic Stringpool.
 402   const char* filename_;
 403   // The list of version names.
 404   Need_versions need_versions_;
 405 };
 406
 407 // This class handles version definitions and references which go into
 408 // the output file.
 409
 410 class Versions
 411 {
 412  public:
 413   Versions()
 414     : defs_(), needs_(), version_table_(), is_finalized_(false)
 415   { }
 416
 417   ~Versions();
 418
 419   // SYM is going into the dynamic symbol table and has a version.
 420   // Record the appropriate version information.
 421   void
 422   record_version(const Symbol_table* symtab, Stringpool*, const Symbol* sym);
 423
 424   // Set the version indexes.  DYNSYM_INDEX is the index we should use
 425   // for the next dynamic symbol.  We add new dynamic symbols to SYMS
 426   // and return an updated DYNSYM_INDEX.
 427   unsigned int
 428   finalize(const Target*, Symbol_table* symtab, unsigned int dynsym_index,
 429            std::vector<Symbol*>* syms);
 430
 431   // Return whether there are any version definitions.
 432   bool
 433   any_defs() const
 434   { return !this->defs_.empty(); }
 435
 436   // Return whether there are any version references.
 437   bool
 438   any_needs() const
 439   { return !this->needs_.empty(); }
 440
 441   // Build an allocated buffer holding the contents of the symbol
 442   // version section (.gnu.version).
 443   template<int size, bool big_endian>
 444   void
 445   symbol_section_contents(const Symbol_table*, const Stringpool*,
 446                           unsigned int local_symcount,
 447                           const std::vector<Symbol*>& syms,
 448                           unsigned char**, unsigned int*
 449                           ACCEPT_SIZE_ENDIAN) const;
 450
 451   // Build an allocated buffer holding the contents of the version
 452   // definition section (.gnu.version_d).
 453   template<int size, bool big_endian>
 454   void
 455   def_section_contents(const Stringpool*, unsigned char**,
 456                        unsigned int* psize, unsigned int* pentries
 457                        ACCEPT_SIZE_ENDIAN) const;
 458
 459   // Build an allocated buffer holding the contents of the version
 460   // reference section (.gnu.version_r).
 461   template<int size, bool big_endian>
 462   void
 463   need_section_contents(const Stringpool*, unsigned char**,
 464                         unsigned int* psize, unsigned int* pentries
 465                         ACCEPT_SIZE_ENDIAN) const;
 466
 467  private:
 468   // The type of the list of version definitions.
 469   typedef std::vector<Verdef*> Defs;
 470
 471   // The type of the list of version references.
 472   typedef std::vector<Verneed*> Needs;
 473
 474   // Handle a symbol SYM defined with version VERSION.
 475   void
 476   add_def(const Symbol* sym, const char* version, Stringpool::Key);
 477
 478   // Add a reference to version NAME in file FILENAME.
 479   void
 480   add_need(Stringpool*, const char* filename, const char* name,
 481            Stringpool::Key);
 482
 483   // Get the dynamic object to use for SYM.
 484   Dynobj*
 485   get_dynobj_for_sym(const Symbol_table*, const Symbol* sym) const;
 486
 487   // Return the version index to use for SYM.
 488   unsigned int
 489   version_index(const Symbol_table*, const Stringpool*,
 490                 const Symbol* sym) const;
 491
 492   // We keep a hash table mapping canonicalized name/version pairs to
 493   // a version base.
 494   typedef std::pair<Stringpool::Key, Stringpool::Key> Key;
 495
 496   struct Version_table_hash
 497   {
 498     size_t
 499     operator()(const Key& k) const
 500     { return k.first + k.second; }
 501   };
 502
 503   struct Version_table_eq
 504   {
 505     bool
 506     operator()(const Key& k1, const Key& k2) const
 507     { return k1.first == k2.first && k1.second == k2.second; }
 508   };
 509
 510   typedef Unordered_map<Key, Version_base*, Version_table_hash,
 511                         Version_table_eq> Version_table;
 512
 513   // The version definitions.
 514   Defs defs_;
 515   // The version references.
 516   Needs needs_;
 517   // The mapping from a canonicalized version/filename pair to a
 518   // version index.  The filename may be NULL.
 519   Version_table version_table_;
 520   // Whether the version indexes have been set.
 521   bool is_finalized_;
 522 };
 523
 524 } // End namespace gold.
 525
 526 #endif // !defined(GOLD_DYNOBJ_H)