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// dynobj.h -- dynamic object support for gold   -*- C++ -*-

// Copyright 2006, 2007, 2008 Free Software Foundation, Inc.

// Written by Ian Lance Taylor <iant@google.com>.

// This file is part of gold.

// This program is free software; you can redistribute it and/or modify

// it under the terms of the GNU General Public License as published by

// the Free Software Foundation; either version 3 of the License, or

// (at your option) any later version.

// This program is distributed in the hope that it will be useful,

// but WITHOUT ANY WARRANTY; without even the implied warranty of

// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License

// along with this program; if not, write to the Free Software

// Foundation, Inc., 51 Franklin Street - Fifth Floor, Boston,

// MA 02110-1301, USA.

#ifndef GOLD_DYNOBJ_H

#define GOLD_DYNOBJ_H

#include <vector>

#include "stringpool.h"

#include "object.h"

namespace gold

{

class Version_script_info;

// A dynamic object (ET_DYN).  This is an abstract base class itself.

// The implementations is the template class Sized_dynobj.

class Dynobj : public Object

{

 public:

  // We keep a list of all the DT_NEEDED entries we find.

  typedef std::vector<std::string> Needed;

  Dynobj(const std::string& name, Input_file* input_file, off_t offset = 0);

  // Return the name to use in a DT_NEEDED entry for this object.

  const char*

  soname() const

  { return this->soname_.c_str(); }

  // Return the list of DT_NEEDED strings.

  const Needed&

  needed() const

  { return this->needed_; }

  // Return whether this dynamic object has any DT_NEEDED entries

  // which were not seen during the link.

  bool

  has_unknown_needed_entries() const

  {

    gold_assert(this->unknown_needed_ != UNKNOWN_NEEDED_UNSET);

    return this->unknown_needed_ == UNKNOWN_NEEDED_TRUE;

  }

  // Set whether this dynamic object has any DT_NEEDED entries which

  // were not seen during the link.

  void

  set_has_unknown_needed_entries(bool set)

  {

    gold_assert(this->unknown_needed_ == UNKNOWN_NEEDED_UNSET);

    this->unknown_needed_ = set ? UNKNOWN_NEEDED_TRUE : UNKNOWN_NEEDED_FALSE;

  }

  // Compute the ELF hash code for a string.

  static uint32_t

  elf_hash(const char*);

  // Create a standard ELF hash table, setting *PPHASH and *PHASHLEN.

  // DYNSYMS is the global dynamic symbols.  LOCAL_DYNSYM_COUNT is the

  // number of local dynamic symbols, which is the index of the first

  // dynamic gobal symbol.

  static void

  create_elf_hash_table(const std::vector<Symbol*>& dynsyms,

                        unsigned int local_dynsym_count,

                        unsigned char** pphash,

                        unsigned int* phashlen);

  // Create a GNU hash table, setting *PPHASH and *PHASHLEN.  DYNSYMS

  // is the global dynamic symbols.  LOCAL_DYNSYM_COUNT is the number

  // of local dynamic symbols, which is the index of the first dynamic

  // gobal symbol.

  static void

  create_gnu_hash_table(const std::vector<Symbol*>& dynsyms,

                        unsigned int local_dynsym_count,

                        unsigned char** pphash, unsigned int* phashlen);

 protected:

  // Set the DT_SONAME string.

  void

  set_soname_string(const char* s)

  { this->soname_.assign(s); }

  // Add an entry to the list of DT_NEEDED strings.

  void

  add_needed(const char* s)

  { this->needed_.push_back(std::string(s)); }

 private:

  // Compute the GNU hash code for a string.

  static uint32_t

  gnu_hash(const char*);

  // Compute the number of hash buckets to use.

  static unsigned int

  compute_bucket_count(const std::vector<uint32_t>& hashcodes,

                       bool for_gnu_hash_table);

  // Sized version of create_elf_hash_table.

  template<bool big_endian>

  static void

  sized_create_elf_hash_table(const std::vector<uint32_t>& bucket,

                              const std::vector<uint32_t>& chain,

                              unsigned char* phash,

                              unsigned int hashlen);

  // Sized version of create_gnu_hash_table.

  template<int size, bool big_endian>

  static void

  sized_create_gnu_hash_table(const std::vector<Symbol*>& hashed_dynsyms,

                              const std::vector<uint32_t>& dynsym_hashvals,

                              unsigned int unhashed_dynsym_count,

                              unsigned char** pphash,

                              unsigned int* phashlen);

  // Values for the has_unknown_needed_entries_ field.

  enum Unknown_needed

  {

    UNKNOWN_NEEDED_UNSET,

    UNKNOWN_NEEDED_TRUE,

    UNKNOWN_NEEDED_FALSE

  };

  // The DT_SONAME name, if any.

  std::string soname_;

  // The list of DT_NEEDED entries.

  Needed needed_;

  // Whether this dynamic object has any DT_NEEDED entries not seen

  // during the link.

  Unknown_needed unknown_needed_;

};

// A dynamic object, size and endian specific version.

template<int size, bool big_endian>

class Sized_dynobj : public Dynobj

{

 public:

  typedef typename Sized_relobj<size, big_endian>::Symbols Symbols;

  Sized_dynobj(const std::string& name, Input_file* input_file, off_t offset,

               const typename elfcpp::Ehdr<size, big_endian>&);

  // Set up the object file based on TARGET.

  void

  setup();

  // Read the symbols.

  void

  do_read_symbols(Read_symbols_data*);

  // Lay out the input sections.

  void

  do_layout(Symbol_table*, Layout*, Read_symbols_data*);

  // Add the symbols to the symbol table.

  void

  do_add_symbols(Symbol_table*, Read_symbols_data*, Layout*);

  // Get the size of a section.

  uint64_t

  do_section_size(unsigned int shndx)

  { return this->elf_file_.section_size(shndx); }

  // Get the name of a section.

  std::string

  do_section_name(unsigned int shndx)

  { return this->elf_file_.section_name(shndx); }

  // Return a view of the contents of a section.  Set *PLEN to the

  // size.

  Object::Location

  do_section_contents(unsigned int shndx)

  { return this->elf_file_.section_contents(shndx); }

  // Return section flags.

  uint64_t

  do_section_flags(unsigned int shndx)

  { return this->elf_file_.section_flags(shndx); }

  // Not used for dynobj.

  uint64_t

  do_section_entsize(unsigned int )

  { gold_unreachable(); }

  // Return section address.

  uint64_t

  do_section_address(unsigned int shndx)

  { return this->elf_file_.section_addr(shndx); }

  // Return section type.

  unsigned int

  do_section_type(unsigned int shndx)

  { return this->elf_file_.section_type(shndx); }

  // Return the section link field.

  unsigned int

  do_section_link(unsigned int shndx)

  { return this->elf_file_.section_link(shndx); }

  // Return the section link field.

  unsigned int

  do_section_info(unsigned int shndx)

  { return this->elf_file_.section_info(shndx); }

  // Return the section alignment.

  uint64_t

  do_section_addralign(unsigned int shndx)

  { return this->elf_file_.section_addralign(shndx); }

  // Return the Xindex structure to use.

  Xindex*

  do_initialize_xindex();

  // Get symbol counts.

  void

  do_get_global_symbol_counts(const Symbol_table*, size_t*, size_t*) const;

 private:

  // For convenience.

  typedef Sized_dynobj<size, big_endian> This;

  static const int shdr_size = elfcpp::Elf_sizes<size>::shdr_size;

  static const int sym_size = elfcpp::Elf_sizes<size>::sym_size;

  static const int dyn_size = elfcpp::Elf_sizes<size>::dyn_size;

  typedef elfcpp::Shdr<size, big_endian> Shdr;

  typedef elfcpp::Dyn<size, big_endian> Dyn;

  // Adjust a section index if necessary.

  unsigned int

  adjust_shndx(unsigned int shndx)

  {

    if (shndx >= elfcpp::SHN_LORESERVE)

      shndx += this->elf_file_.large_shndx_offset();

    return shndx;

  }

  // Find the dynamic symbol table and the version sections, given the

  // section headers.

  void

  find_dynsym_sections(const unsigned char* pshdrs,

                       unsigned int* pversym_shndx,

                       unsigned int* pverdef_shndx,

                       unsigned int* pverneed_shndx,

                       unsigned int* pdynamic_shndx);

  // Read the dynamic symbol section SHNDX.

  void

  read_dynsym_section(const unsigned char* pshdrs, unsigned int shndx,

                      elfcpp::SHT type, unsigned int link,

                      File_view** view, section_size_type* view_size,

                      unsigned int* view_info);

  // Read the dynamic tags.

  void

  read_dynamic(const unsigned char* pshdrs, unsigned int dynamic_shndx,

               unsigned int strtab_shndx, const unsigned char* strtabu,

               off_t strtab_size);

  // Mapping from version number to version name.

  typedef std::vector<const char*> Version_map;

  // Create the version map.

  void

  make_version_map(Read_symbols_data* sd, Version_map*) const;

  // Add version definitions to the version map.

  void

  make_verdef_map(Read_symbols_data* sd, Version_map*) const;

  // Add version references to the version map.

  void

  make_verneed_map(Read_symbols_data* sd, Version_map*) const;

  // Add an entry to the version map.

  void

  set_version_map(Version_map*, unsigned int ndx, const char* name) const;

  // General access to the ELF file.

  elfcpp::Elf_file<size, big_endian, Object> elf_file_;

  // The section index of the dynamic symbol table.

  unsigned int dynsym_shndx_;

  // The entries in the symbol table for the symbols.  We only keep

  // this if we need it to print symbol information.

  Symbols* symbols_;

  // Number of defined symbols.

  size_t defined_count_;

};

// A base class for Verdef and Verneed_version which just handles the

// version index which will be stored in the SHT_GNU_versym section.

class Version_base

{

 public:

  Version_base()

    : index_(-1U)

  { }

  virtual

  ~Version_base()

  { }

  // Return the version index.

  unsigned int

  index() const

  {

    gold_assert(this->index_ != -1U);

    return this->index_;

  }

  // Set the version index.

  void

  set_index(unsigned int index)

  {

    gold_assert(this->index_ == -1U);

    this->index_ = index;

  }

  // Clear the weak flag in a version definition.

  virtual void

  clear_weak() = 0;

 private:

  Version_base(const Version_base&);

  Version_base& operator=(const Version_base&);

  // The index of the version definition or reference.

  unsigned int index_;

};

// This class handles a version being defined in the file we are

// generating.

class Verdef : public Version_base

{

 public:

  Verdef(const char* name, const std::vector<std::string>& deps,

         bool is_base, bool is_weak, bool is_symbol_created)

    : name_(name), deps_(deps), is_base_(is_base), is_weak_(is_weak),

      is_symbol_created_(is_symbol_created)

  { }

  // Return the version name.

  const char*

  name() const

  { return this->name_; }

  // Return the number of dependencies.

  unsigned int

  count_dependencies() const

  { return this->deps_.size(); }

  // Add a dependency to this version.  The NAME should be

  // canonicalized in the dynamic Stringpool.

  void

  add_dependency(const char* name)

  { this->deps_.push_back(name); }

  // Return whether this definition is weak.

  bool

  is_weak() const

  { return this->is_weak_; }

  // Clear the weak flag.

  void

  clear_weak()

  { this->is_weak_ = false; }

  // Return whether a version symbol has been created for this

  // definition.

  bool

  is_symbol_created() const

  { return this->is_symbol_created_; }

  // Write contents to buffer.

  template<int size, bool big_endian>

  unsigned char*

  write(const Stringpool*, bool is_last, unsigned char*) const;

 private:

  Verdef(const Verdef&);

  Verdef& operator=(const Verdef&);

  // The type of the list of version dependencies.  Each dependency

  // should be canonicalized in the dynamic Stringpool.

  typedef std::vector<std::string> Deps;

  // The name of this version.  This should be canonicalized in the

  // dynamic Stringpool.

  const char* name_;

  // A list of other versions which this version depends upon.

  Deps deps_;

  // Whether this is the base version.

  bool is_base_;

  // Whether this version is weak.

  bool is_weak_;

  // Whether a version symbol has been created.

  bool is_symbol_created_;

};

// A referened version.  This will be associated with a filename by

// Verneed.

class Verneed_version : public Version_base

{

 public:

  Verneed_version(const char* version)

    : version_(version)

  { }

  // Return the version name.

  const char*

  version() const

  { return this->version_; }

  // Clear the weak flag.  This is invalid for a reference.

  void

  clear_weak()

  { gold_unreachable(); }

 private:

  Verneed_version(const Verneed_version&);

  Verneed_version& operator=(const Verneed_version&);

  const char* version_;

};

// Version references in a single dynamic object.

class Verneed

{

 public:

  Verneed(const char* filename)

    : filename_(filename), need_versions_()

  { }

  ~Verneed();

  // Return the file name.

  const char*

  filename() const

  { return this->filename_; }

  // Return the number of versions.

  unsigned int

  count_versions() const

  { return this->need_versions_.size(); }

  // Add a version name.  The name should be canonicalized in the

  // dynamic Stringpool.  If the name is already present, this does

  // nothing.

  Verneed_version*

  add_name(const char* name);

  // Set the version indexes, starting at INDEX.  Return the updated

  // INDEX.

  unsigned int

  finalize(unsigned int index);

  // Write contents to buffer.

  template<int size, bool big_endian>

  unsigned char*

  write(const Stringpool*, bool is_last, unsigned char*) const;

 private:

  Verneed(const Verneed&);

  Verneed& operator=(const Verneed&);

  // The type of the list of version names.  Each name should be

  // canonicalized in the dynamic Stringpool.

  typedef std::vector<Verneed_version*> Need_versions;

  // The filename of the dynamic object.  This should be

  // canonicalized in the dynamic Stringpool.

  const char* filename_;

  // The list of version names.

  Need_versions need_versions_;

};

// This class handles version definitions and references which go into

// the output file.

class Versions

{

 public:

  Versions(const Version_script_info&, Stringpool*);

  ~Versions();

  // SYM is going into the dynamic symbol table and has a version.

  // Record the appropriate version information.

  void

  record_version(const Symbol_table* symtab, Stringpool*, const Symbol* sym);

  // Set the version indexes.  DYNSYM_INDEX is the index we should use

  // for the next dynamic symbol.  We add new dynamic symbols to SYMS

  // and return an updated DYNSYM_INDEX.

  unsigned int

  finalize(Symbol_table* symtab, unsigned int dynsym_index,

           std::vector<Symbol*>* syms);

  // Return whether there are any version definitions.

  bool

  any_defs() const

  { return !this->defs_.empty(); }

  // Return whether there are any version references.

  bool

  any_needs() const

  { return !this->needs_.empty(); }

  // Build an allocated buffer holding the contents of the symbol

  // version section (.gnu.version).

  template<int size, bool big_endian>

  void

  symbol_section_contents(const Symbol_table*, const Stringpool*,

                          unsigned int local_symcount,

                          const std::vector<Symbol*>& syms,

                          unsigned char**, unsigned int*) const;

  // Build an allocated buffer holding the contents of the version

  // definition section (.gnu.version_d).

  template<int size, bool big_endian>

  void

  def_section_contents(const Stringpool*, unsigned char**,

                       unsigned int* psize, unsigned int* pentries) const;

  // Build an allocated buffer holding the contents of the version

  // reference section (.gnu.version_r).

  template<int size, bool big_endian>

  void

  need_section_contents(const Stringpool*, unsigned char**,

                        unsigned int* psize, unsigned int* pentries) const;

  const Version_script_info&

  version_script() const

  { return this->version_script_; }

 private:

  Versions(const Versions&);

  Versions& operator=(const Versions&);

  // The type of the list of version definitions.

  typedef std::vector<Verdef*> Defs;

  // The type of the list of version references.

  typedef std::vector<Verneed*> Needs;

  // Handle a symbol SYM defined with version VERSION.

  void

  add_def(const Symbol* sym, const char* version, Stringpool::Key);

  // Add a reference to version NAME in file FILENAME.

  void

  add_need(Stringpool*, const char* filename, const char* name,

           Stringpool::Key);

  // Get the dynamic object to use for SYM.

  Dynobj*

  get_dynobj_for_sym(const Symbol_table*, const Symbol* sym) const;

  // Return the version index to use for SYM.

  unsigned int

  version_index(const Symbol_table*, const Stringpool*,

                const Symbol* sym) const;

  // Define the base version of a shared library.

  void

  define_base_version(Stringpool* dynpool);

  // We keep a hash table mapping canonicalized name/version pairs to

  // a version base.

  typedef std::pair<Stringpool::Key, Stringpool::Key> Key;

  struct Version_table_hash

  {

    size_t

    operator()(const Key& k) const

    { return k.first + k.second; }

  };

  struct Version_table_eq

  {

    bool

    operator()(const Key& k1, const Key& k2) const

    { return k1.first == k2.first && k1.second == k2.second; }

  };

  typedef Unordered_map<Key, Version_base*, Version_table_hash,

                        Version_table_eq> Version_table;

  // The version definitions.

  Defs defs_;

  // The version references.

  Needs needs_;

  // The mapping from a canonicalized version/filename pair to a

  // version index.  The filename may be NULL.

  Version_table version_table_;

  // Whether the version indexes have been set.

  bool is_finalized_;

  // Contents of --version-script, if passed, or NULL.

  const Version_script_info& version_script_;

  // Whether we need to insert a base version.  This is only used for

  // shared libaries and is cleared when the base version is defined.

  bool needs_base_version_;

};

} // End namespace gold.

#endif // !defined(GOLD_DYNOBJ_H)