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