gold/dynobj.h

   1 // dynobj.h -- dynamic object support for gold   -*- C++ -*-
   2
   3 #ifndef GOLD_DYNOBJ_H
   4 #define GOLD_DYNOBJ_H
   5
   6 #include <vector>
   7
   8 #include "stringpool.h"
   9 #include "object.h"
  10
  11 namespace gold
  12 {
  13
  14 class General_options;
  15
  16 // A dynamic object (ET_DYN).  This is an abstract base class itself.
  17 // The implementations is the template class Sized_dynobj.
  18
  19 class Dynobj : public Object
  20 {
  21  public:
  22   Dynobj(const std::string& name, Input_file* input_file, off_t offset = 0)
  23     : Object(name, input_file, true, offset), soname_()
  24   { }
  25
  26   // Return the name to use in a DT_NEEDED entry for this object.
  27   const char*
  28   soname() const;
  29
  30   // Compute the ELF hash code for a string.
  31   static uint32_t
  32   elf_hash(const char*);
  33
  34   // Create a standard ELF hash table, setting *PPHASH and *PHASHLEN.
  35   // DYNSYMS is the global dynamic symbols.  LOCAL_DYNSYM_COUNT is the
  36   // number of local dynamic symbols, which is the index of the first
  37   // dynamic gobal symbol.
  38   static void
  39   create_elf_hash_table(const Target*, const std::vector<Symbol*>& dynsyms,
  40                         unsigned int local_dynsym_count,
  41                         unsigned char** pphash,
  42                         unsigned int* phashlen);
  43
  44   // Create a GNU hash table, setting *PPHASH and *PHASHLEN.  DYNSYMS
  45   // is the global dynamic symbols.  LOCAL_DYNSYM_COUNT is the number
  46   // of local dynamic symbols, which is the index of the first dynamic
  47   // gobal symbol.
  48   static void
  49   create_gnu_hash_table(const Target*, const std::vector<Symbol*>& dynsyms,
  50                         unsigned int local_dynsym_count,
  51                         unsigned char** pphash, unsigned int* phashlen);
  52
  53  protected:
  54   // Set the DT_SONAME string.
  55   void
  56   set_soname_string(const char* s)
  57   { this->soname_.assign(s); }
  58
  59  private:
  60   // Compute the GNU hash code for a string.
  61   static uint32_t
  62   gnu_hash(const char*);
  63
  64   // Compute the number of hash buckets to use.
  65   static unsigned int
  66   compute_bucket_count(const std::vector<uint32_t>& hashcodes,
  67                        bool for_gnu_hash_table);
  68
  69   // Sized version of create_elf_hash_table.
  70   template<bool big_endian>
  71   static void
  72   sized_create_elf_hash_table(const std::vector<uint32_t>& bucket,
  73                               const std::vector<uint32_t>& chain,
  74                               unsigned char* phash,
  75                               unsigned int hashlen);
  76
  77   // Sized version of create_gnu_hash_table.
  78   template<int size, bool big_endian>
  79   static void
  80   sized_create_gnu_hash_table(const std::vector<Symbol*>& hashed_dynsyms,
  81                               const std::vector<uint32_t>& dynsym_hashvals,
  82                               unsigned int unhashed_dynsym_count,
  83                               unsigned char** pphash,
  84                               unsigned int* phashlen);
  85
  86   // The DT_SONAME name, if any.
  87   std::string soname_;
  88 };
  89
  90 // A dynamic object, size and endian specific version.
  91
  92 template<int size, bool big_endian>
  93 class Sized_dynobj : public Dynobj
  94 {
  95  public:
  96   Sized_dynobj(const std::string& name, Input_file* input_file, off_t offset,
  97                const typename elfcpp::Ehdr<size, big_endian>&);
  98
  99   // Set up the object file based on the ELF header.
 100   void
 101   setup(const typename elfcpp::Ehdr<size, big_endian>&);
 102
 103   // Read the symbols.
 104   void
 105   do_read_symbols(Read_symbols_data*);
 106
 107   // Lay out the input sections.
 108   void
 109   do_layout(const General_options&, Symbol_table*, Layout*,
 110             Read_symbols_data*);
 111
 112   // Add the symbols to the symbol table.
 113   void
 114   do_add_symbols(Symbol_table*, Read_symbols_data*);
 115
 116   // Get the name of a section.
 117   std::string
 118   do_section_name(unsigned int shndx)
 119   { return this->elf_file_.section_name(shndx); }
 120
 121   // Return a view of the contents of a section.  Set *PLEN to the
 122   // size.
 123   Object::Location
 124   do_section_contents(unsigned int shndx)
 125   { return this->elf_file_.section_contents(shndx); }
 126
 127   // Return section flags.
 128   uint64_t
 129   do_section_flags(unsigned int shndx)
 130   { return this->elf_file_.section_flags(shndx); }
 131
 132  private:
 133   // For convenience.
 134   typedef Sized_dynobj<size, big_endian> This;
 135   static const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;
 136   static const int sym_size = elfcpp::Elf_sizes<size>::sym_size;
 137   static const int dyn_size = elfcpp::Elf_sizes<size>::dyn_size;
 138   typedef elfcpp::Shdr<size, big_endian> Shdr;
 139   typedef elfcpp::Dyn<size, big_endian> Dyn;
 140
 141   // Find the dynamic symbol table and the version sections, given the
 142   // section headers.
 143   void
 144   find_dynsym_sections(const unsigned char* pshdrs,
 145                        unsigned int* pdynshm_shndx,
 146                        unsigned int* pversym_shndx,
 147                        unsigned int* pverdef_shndx,
 148                        unsigned int* pverneed_shndx,
 149                        unsigned int* pdynamic_shndx);
 150
 151   // Read the dynamic symbol section SHNDX.
 152   void
 153   read_dynsym_section(const unsigned char* pshdrs, unsigned int shndx,
 154                       elfcpp::SHT type, unsigned int link,
 155                       File_view** view, off_t* view_size,
 156                       unsigned int* view_info);
 157
 158   // Set the SONAME from the SHT_DYNAMIC section at DYNAMIC_SHNDX.
 159   // The STRTAB parameters may have the relevant string table.
 160   void
 161   set_soname(const unsigned char* pshdrs, unsigned int dynamic_shndx,
 162              unsigned int strtab_shndx, const unsigned char* strtabu,
 163              off_t strtab_size);
 164
 165   // Mapping from version number to version name.
 166   typedef std::vector<const char*> Version_map;
 167
 168   // Create the version map.
 169   void
 170   make_version_map(Read_symbols_data* sd, Version_map*) const;
 171
 172   // Add version definitions to the version map.
 173   void
 174   make_verdef_map(Read_symbols_data* sd, Version_map*) const;
 175
 176   // Add version references to the version map.
 177   void
 178   make_verneed_map(Read_symbols_data* sd, Version_map*) const;
 179
 180   // Add an entry to the version map.
 181   void
 182   set_version_map(Version_map*, unsigned int ndx, const char* name) const;
 183
 184   // General access to the ELF file.
 185   elfcpp::Elf_file<size, big_endian, Object> elf_file_;
 186 };
 187
 188 // A base class for Verdef and Verneed_version which just handles the
 189 // version index which will be stored in the SHT_GNU_versym section.
 190
 191 class Version_base
 192 {
 193  public:
 194   Version_base()
 195     : index_(-1U)
 196   { }
 197
 198   virtual
 199   ~Version_base()
 200   { }
 201
 202   // Return the version index.
 203   unsigned int
 204   index() const
 205   {
 206     gold_assert(this->index_ != -1U);
 207     return this->index_;
 208   }
 209
 210   // Set the version index.
 211   void
 212   set_index(unsigned int index)
 213   {
 214     gold_assert(this->index_ == -1U);
 215     this->index_ = index;
 216   }
 217
 218   // Clear the weak flag in a version definition.
 219   virtual void
 220   clear_weak() = 0;
 221
 222  private:
 223   Version_base(const Version_base&);
 224   Version_base& operator=(const Version_base&);
 225
 226   // The index of the version definition or reference.
 227   unsigned int index_;
 228 };
 229
 230 // This class handles a version being defined in the file we are
 231 // generating.
 232
 233 class Verdef : public Version_base
 234 {
 235  public:
 236   Verdef(const char* name, bool is_base, bool is_weak, bool is_symbol_created)
 237     : name_(name), deps_(), is_base_(is_base), is_weak_(is_weak),
 238       is_symbol_created_(is_symbol_created)
 239   { }
 240
 241   // Return the version name.
 242   const char*
 243   name() const
 244   { return this->name_; }
 245
 246   // Return the number of dependencies.
 247   unsigned int
 248   count_dependencies() const
 249   { return this->deps_.size(); }
 250
 251   // Add a dependency to this version.  The NAME should be
 252   // canonicalized in the dynamic Stringpool.
 253   void
 254   add_dependency(const char* name)
 255   { this->deps_.push_back(name); }
 256
 257   // Return whether this definition is weak.
 258   bool
 259   is_weak() const
 260   { return this->is_weak_; }
 261
 262   // Clear the weak flag.
 263   void
 264   clear_weak()
 265   { this->is_weak_ = false; }
 266
 267   // Return whether a version symbol has been created for this
 268   // definition.
 269   bool
 270   is_symbol_created() const
 271   { return this->is_symbol_created_; }
 272
 273   // Write contents to buffer.
 274   template<int size, bool big_endian>
 275   unsigned char*
 276   write(const Stringpool*, bool is_last, unsigned char*
 277         ACCEPT_SIZE_ENDIAN) const;
 278
 279  private:
 280   Verdef(const Verdef&);
 281   Verdef& operator=(const Verdef&);
 282
 283   // The type of the list of version dependencies.  Each dependency
 284   // should be canonicalized in the dynamic Stringpool.
 285   typedef std::vector<const char*> Deps;
 286
 287   // The name of this version.  This should be canonicalized in the
 288   // dynamic Stringpool.
 289   const char* name_;
 290   // A list of other versions which this version depends upon.
 291   Deps deps_;
 292   // Whether this is the base version.
 293   bool is_base_;
 294   // Whether this version is weak.
 295   bool is_weak_;
 296   // Whether a version symbol has been created.
 297   bool is_symbol_created_;
 298 };
 299
 300 // A referened version.  This will be associated with a filename by
 301 // Verneed.
 302
 303 class Verneed_version : public Version_base
 304 {
 305  public:
 306   Verneed_version(const char* version)
 307     : version_(version)
 308   { }
 309
 310   // Return the version name.
 311   const char*
 312   version() const
 313   { return this->version_; }
 314
 315   // Clear the weak flag.  This is invalid for a reference.
 316   void
 317   clear_weak()
 318   { gold_unreachable(); }
 319
 320  private:
 321   Verneed_version(const Verneed_version&);
 322   Verneed_version& operator=(const Verneed_version&);
 323
 324   const char* version_;
 325 };
 326
 327 // Version references in a single dynamic object.
 328
 329 class Verneed
 330 {
 331  public:
 332   Verneed(const char* filename)
 333     : filename_(filename), need_versions_()
 334   { }
 335
 336   ~Verneed();
 337
 338   // Return the file name.
 339   const char*
 340   filename() const
 341   { return this->filename_; }
 342
 343   // Return the number of versions.
 344   unsigned int
 345   count_versions() const
 346   { return this->need_versions_.size(); }
 347
 348   // Add a version name.  The name should be canonicalized in the
 349   // dynamic Stringpool.  If the name is already present, this does
 350   // nothing.
 351   Verneed_version*
 352   add_name(const char* name);
 353
 354   // Set the version indexes, starting at INDEX.  Return the updated
 355   // INDEX.
 356   unsigned int
 357   finalize(unsigned int index);
 358
 359   // Write contents to buffer.
 360   template<int size, bool big_endian>
 361   unsigned char*
 362   write(const Stringpool*, bool is_last, unsigned char*
 363         ACCEPT_SIZE_ENDIAN) const;
 364
 365  private:
 366   Verneed(const Verneed&);
 367   Verneed& operator=(const Verneed&);
 368
 369   // The type of the list of version names.  Each name should be
 370   // canonicalized in the dynamic Stringpool.
 371   typedef std::vector<Verneed_version*> Need_versions;
 372
 373   // The filename of the dynamic object.  This should be
 374   // canonicalized in the dynamic Stringpool.
 375   const char* filename_;
 376   // The list of version names.
 377   Need_versions need_versions_;
 378 };
 379
 380 // This class handles version definitions and references which go into
 381 // the output file.
 382
 383 class Versions
 384 {
 385  public:
 386   Versions()
 387     : defs_(), needs_(), version_table_(), is_finalized_(false)
 388   { }
 389
 390   ~Versions();
 391
 392   // SYM is going into the dynamic symbol table and has a version.
 393   // Record the appropriate version information.
 394   void
 395   record_version(const General_options*, Stringpool*, const Symbol* sym);
 396
 397   // Set the version indexes.  DYNSYM_INDEX is the index we should use
 398   // for the next dynamic symbol.  We add new dynamic symbols to SYMS
 399   // and return an updated DYNSYM_INDEX.
 400   unsigned int
 401   finalize(const Target*, Symbol_table* symtab, unsigned int dynsym_index,
 402            std::vector<Symbol*>* syms);
 403
 404   // Return whether there are any version definitions.
 405   bool
 406   any_defs() const
 407   { return !this->defs_.empty(); }
 408
 409   // Return whether there are any version references.
 410   bool
 411   any_needs() const
 412   { return !this->needs_.empty(); }
 413
 414   // Build an allocated buffer holding the contents of the symbol
 415   // version section (.gnu.version).
 416   template<int size, bool big_endian>
 417   void
 418   symbol_section_contents(const Stringpool*, unsigned int local_symcount,
 419                           const std::vector<Symbol*>& syms,
 420                           unsigned char**, unsigned int*
 421                           ACCEPT_SIZE_ENDIAN) const;
 422
 423   // Build an allocated buffer holding the contents of the version
 424   // definition section (.gnu.version_d).
 425   template<int size, bool big_endian>
 426   void
 427   def_section_contents(const Stringpool*, unsigned char**,
 428                        unsigned int* psize, unsigned int* pentries
 429                        ACCEPT_SIZE_ENDIAN) const;
 430
 431   // Build an allocated buffer holding the contents of the version
 432   // reference section (.gnu.version_r).
 433   template<int size, bool big_endian>
 434   void
 435   need_section_contents(const Stringpool*, unsigned char**,
 436                         unsigned int* psize, unsigned int* pentries
 437                         ACCEPT_SIZE_ENDIAN) const;
 438
 439  private:
 440   // The type of the list of version definitions.
 441   typedef std::vector<Verdef*> Defs;
 442
 443   // The type of the list of version references.
 444   typedef std::vector<Verneed*> Needs;
 445
 446   // Handle a symbol SYM defined with version VERSION.
 447   void
 448   add_def(const General_options*, const Symbol* sym, const char* version,
 449           Stringpool::Key);
 450
 451   // Add a reference to version NAME in file FILENAME.
 452   void
 453   add_need(Stringpool*, const char* filename, const char* name,
 454            Stringpool::Key);
 455
 456   // Return the version index to use for SYM.
 457   unsigned int
 458   version_index(const Stringpool*, const Symbol* sym) const;
 459
 460   // We keep a hash table mapping canonicalized name/version pairs to
 461   // a version base.
 462   typedef std::pair<Stringpool::Key, Stringpool::Key> Key;
 463
 464   struct Version_table_hash
 465   {
 466     size_t
 467     operator()(const Key& k) const
 468     { return k.first + k.second; }
 469   };
 470
 471   struct Version_table_eq
 472   {
 473     bool
 474     operator()(const Key& k1, const Key& k2) const
 475     { return k1.first == k2.first && k1.second == k2.second; }
 476   };
 477
 478   typedef Unordered_map<Key, Version_base*, Version_table_hash,
 479                         Version_table_eq> Version_table;
 480
 481   // The version definitions.
 482   Defs defs_;
 483   // The version references.
 484   Needs needs_;
 485   // The mapping from a canonicalized version/filename pair to a
 486   // version index.  The filename may be NULL.
 487   Version_table version_table_;
 488   // Whether the version indexes have been set.
 489   bool is_finalized_;
 490 };
 491
 492 } // End namespace gold.
 493
 494 #endif // !defined(GOLD_DYNOBJ_H)