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