text: // dynobj.cc -- dynamic object support for gold
  
  // Copyright 2006, 2007, 2008, 2009, 2010 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.
  
  #include "gold.h"
  
  #include <vector>
  #include <cstring>
  
  #include "elfcpp.h"
  #include "parameters.h"
  #include "script.h"
  #include "symtab.h"
  #include "dynobj.h"
  
  namespace gold
  {
  
  // Class Dynobj.
  
  // Sets up the default soname_ to use, in the (rare) cases we never
  // see a DT_SONAME entry.
  
  Dynobj::Dynobj(const std::string& name, Input_file* input_file, off_t offset)
    : Object(name, input_file, true, offset),
      needed_(),
      unknown_needed_(UNKNOWN_NEEDED_UNSET)
  {
    // This will be overridden by a DT_SONAME entry, hopefully.  But if
    // we never see a DT_SONAME entry, our rule is to use the dynamic
    // object's filename.  The only exception is when the dynamic object
    // is part of an archive (so the filename is the archive's
    // filename).  In that case, we use just the dynobj's name-in-archive.
    this->soname_ = this->input_file()->found_name();
    if (this->offset() != 0)
      {
        std::string::size_type open_paren = this->name().find('(');
        std::string::size_type close_paren = this->name().find(')');
        if (open_paren != std::string::npos && close_paren != std::string::npos)
  	{
  	  // It's an archive, and name() is of the form 'foo.a(bar.so)'.
  	  this->soname_ = this->name().substr(open_paren + 1,
  					      close_paren - (open_paren + 1));
  	}
      }
  }
  
  // Class Sized_dynobj.
  
  template<int size, bool big_endian>
  Sized_dynobj<size, big_endian>::Sized_dynobj(
      const std::string& name,
      Input_file* input_file,
      off_t offset,
      const elfcpp::Ehdr<size, big_endian>& ehdr)
    : Dynobj(name, input_file, offset),
      elf_file_(this, ehdr),
      dynsym_shndx_(-1U),
      symbols_(NULL),
      defined_count_(0)
  {
  }
  
  // Set up the object.
  
  template<int size, bool big_endian>
  void
  Sized_dynobj<size, big_endian>::setup()
  {
    const unsigned int shnum = this->elf_file_.shnum();
    this->set_shnum(shnum);
  }
  
  // Find the SHT_DYNSYM section and the various version sections, and
  // the dynamic section, given the section headers.
  
  template<int size, bool big_endian>
  void
  Sized_dynobj<size, big_endian>::find_dynsym_sections(
      const unsigned char* pshdrs,
      unsigned int* pversym_shndx,
      unsigned int* pverdef_shndx,
      unsigned int* pverneed_shndx,
      unsigned int* pdynamic_shndx)
  {
    *pversym_shndx = -1U;
    *pverdef_shndx = -1U;
    *pverneed_shndx = -1U;
    *pdynamic_shndx = -1U;
  
    unsigned int symtab_shndx = 0;
    unsigned int xindex_shndx = 0;
    unsigned int xindex_link = 0;
    const unsigned int shnum = this->shnum();
    const unsigned char* p = pshdrs;
    for (unsigned int i = 0; i < shnum; ++i, p += This::shdr_size)
      {
        typename This::Shdr shdr(p);
  
        unsigned int* pi;
        switch (shdr.get_sh_type())
  	{
  	case elfcpp::SHT_DYNSYM:
  	  this->dynsym_shndx_ = i;
  	  if (xindex_shndx > 0 && xindex_link == i)
  	    {
  	      Xindex* xindex = new Xindex(this->elf_file_.large_shndx_offset());
  	      xindex->read_symtab_xindex<size, big_endian>(this, xindex_shndx,
  							   pshdrs);
  	      this->set_xindex(xindex);
  	    }
  	  pi = NULL;
  	  break;
  	case elfcpp::SHT_SYMTAB:
  	  symtab_shndx = i;
  	  pi = NULL;
  	  break;
  	case elfcpp::SHT_GNU_versym:
  	  pi = pversym_shndx;
  	  break;
  	case elfcpp::SHT_GNU_verdef:
  	  pi = pverdef_shndx;
  	  break;
  	case elfcpp::SHT_GNU_verneed:
  	  pi = pverneed_shndx;
  	  break;
  	case elfcpp::SHT_DYNAMIC:
  	  pi = pdynamic_shndx;
  	  break;
  	case elfcpp::SHT_SYMTAB_SHNDX:
  	  xindex_shndx = i;
  	  xindex_link = this->adjust_shndx(shdr.get_sh_link());
  	  if (xindex_link == this->dynsym_shndx_)
  	    {
  	      Xindex* xindex = new Xindex(this->elf_file_.large_shndx_offset());
  	      xindex->read_symtab_xindex<size, big_endian>(this, xindex_shndx,
  							   pshdrs);
  	      this->set_xindex(xindex);
  	    }
  	  pi = NULL;
  	  break;
  	default:
  	  pi = NULL;
  	  break;
  	}
  
        if (pi == NULL)
  	continue;
  
        if (*pi != -1U)
  	this->error(_("unexpected duplicate type %u section: %u, %u"),
  		    shdr.get_sh_type(), *pi, i);
  
        *pi = i;
      }
  
    // If there is no dynamic symbol table, use the normal symbol table.
    // On some SVR4 systems, a shared library is stored in an archive.
    // The version stored in the archive only has a normal symbol table.
    // It has an SONAME entry which points to another copy in the file
    // system which has a dynamic symbol table as usual.  This is way of
    // addressing the issues which glibc addresses using GROUP with
    // libc_nonshared.a.
    if (this->dynsym_shndx_ == -1U && symtab_shndx != 0)
      {
        this->dynsym_shndx_ = symtab_shndx;
        if (xindex_shndx > 0 && xindex_link == symtab_shndx)
  	{
  	  Xindex* xindex = new Xindex(this->elf_file_.large_shndx_offset());
  	  xindex->read_symtab_xindex<size, big_endian>(this, xindex_shndx,
  						       pshdrs);
  	  this->set_xindex(xindex);
  	}
      }
  }
  
  // Read the contents of section SHNDX.  PSHDRS points to the section
  // headers.  TYPE is the expected section type.  LINK is the expected
  // section link.  Store the data in *VIEW and *VIEW_SIZE.  The
  // section's sh_info field is stored in *VIEW_INFO.
  
  template<int size, bool big_endian>
  void
  Sized_dynobj<size, big_endian>::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)
  {
    if (shndx == -1U)
      {
        *view = NULL;
        *view_size = 0;
        *view_info = 0;
        return;
      }
  
    typename This::Shdr shdr(pshdrs + shndx * This::shdr_size);
  
    gold_assert(shdr.get_sh_type() == type);
  
    if (this->adjust_shndx(shdr.get_sh_link()) != link)
      this->error(_("unexpected link in section %u header: %u != %u"),
  	        shndx, this->adjust_shndx(shdr.get_sh_link()), link);
  
    *view = this->get_lasting_view(shdr.get_sh_offset(), shdr.get_sh_size(),
  				 true, false);
    *view_size = convert_to_section_size_type(shdr.get_sh_size());
    *view_info = shdr.get_sh_info();
  }
  
  // Read the dynamic tags.  Set the soname field if this shared object
  // has a DT_SONAME tag.  Record the DT_NEEDED tags.  PSHDRS points to
  // the section headers.  DYNAMIC_SHNDX is the section index of the
  // SHT_DYNAMIC section.  STRTAB_SHNDX, STRTAB, and STRTAB_SIZE are the
  // section index and contents of a string table which may be the one
  // associated with the SHT_DYNAMIC section.
  
  template<int size, bool big_endian>
  void
  Sized_dynobj<size, big_endian>::read_dynamic(const unsigned char* pshdrs,
  					     unsigned int dynamic_shndx,
  					     unsigned int strtab_shndx,
  					     const unsigned char* strtabu,
  					     off_t strtab_size)
  {
    typename This::Shdr dynamicshdr(pshdrs + dynamic_shndx * This::shdr_size);
    gold_assert(dynamicshdr.get_sh_type() == elfcpp::SHT_DYNAMIC);
  
    const off_t dynamic_size = dynamicshdr.get_sh_size();
    const unsigned char* pdynamic = this->get_view(dynamicshdr.get_sh_offset(),
  						 dynamic_size, true, false);
  
    const unsigned int link = this->adjust_shndx(dynamicshdr.get_sh_link());
    if (link != strtab_shndx)
      {
        if (link >= this->shnum())
  	{
  	  this->error(_("DYNAMIC section %u link out of range: %u"),
  		      dynamic_shndx, link);
  	  return;
  	}
  
        typename This::Shdr strtabshdr(pshdrs + link * This::shdr_size);
        if (strtabshdr.get_sh_type() != elfcpp::SHT_STRTAB)
  	{
  	  this->error(_("DYNAMIC section %u link %u is not a strtab"),
  		      dynamic_shndx, link);
  	  return;
  	}
  
        strtab_size = strtabshdr.get_sh_size();
        strtabu = this->get_view(strtabshdr.get_sh_offset(), strtab_size, false,
  			       false);
      }
  
    const char* const strtab = reinterpret_cast<const char*>(strtabu);
  
    for (const unsigned char* p = pdynamic;
         p < pdynamic + dynamic_size;
         p += This::dyn_size)
      {
        typename This::Dyn dyn(p);
  
        switch (dyn.get_d_tag())
  	{
  	case elfcpp::DT_NULL:
  	  // We should always see DT_NULL at the end of the dynamic
  	  // tags.
  	  return;
  
  	case elfcpp::DT_SONAME:
  	  {
  	    off_t val = dyn.get_d_val();
  	    if (val >= strtab_size)
  	      this->error(_("DT_SONAME value out of range: %lld >= %lld"),
  			  static_cast<long long>(val),
  			  static_cast<long long>(strtab_size));
  	    else
  	      this->set_soname_string(strtab + val);
  	  }
  	  break;
  
  	case elfcpp::DT_NEEDED:
  	  {
  	    off_t val = dyn.get_d_val();
  	    if (val >= strtab_size)
  	      this->error(_("DT_NEEDED value out of range: %lld >= %lld"),
  			  static_cast<long long>(val),
  			  static_cast<long long>(strtab_size));
  	    else
  	      this->add_needed(strtab + val);
  	  }
  	  break;
  
  	default:
  	  break;
  	}
      }
  
    this->error(_("missing DT_NULL in dynamic segment"));
  }
  
  // Read the symbols and sections from a dynamic object.  We read the
  // dynamic symbols, not the normal symbols.
  
  template<int size, bool big_endian>
  void
  Sized_dynobj<size, big_endian>::do_read_symbols(Read_symbols_data* sd)
  {
    this->read_section_data(&this->elf_file_, sd);
  
    const unsigned char* const pshdrs = sd->section_headers->data();
  
    unsigned int versym_shndx;
    unsigned int verdef_shndx;
    unsigned int verneed_shndx;
    unsigned int dynamic_shndx;
    this->find_dynsym_sections(pshdrs, &versym_shndx, &verdef_shndx,
  			     &verneed_shndx, &dynamic_shndx);
  
    unsigned int strtab_shndx = -1U;
  
    sd->symbols = NULL;
    sd->symbols_size = 0;
    sd->external_symbols_offset = 0;
    sd->symbol_names = NULL;
    sd->symbol_names_size = 0;
    sd->versym = NULL;
    sd->versym_size = 0;
    sd->verdef = NULL;
    sd->verdef_size = 0;
    sd->verdef_info = 0;
    sd->verneed = NULL;
    sd->verneed_size = 0;
    sd->verneed_info = 0;
  
    if (this->dynsym_shndx_ != -1U)
      {
        // Get the dynamic symbols.
        typename This::Shdr dynsymshdr(pshdrs
  				     + this->dynsym_shndx_ * This::shdr_size);
  
        sd->symbols = this->get_lasting_view(dynsymshdr.get_sh_offset(),
  					   dynsymshdr.get_sh_size(), true,
  					   false);
        sd->symbols_size =
  	convert_to_section_size_type(dynsymshdr.get_sh_size());
  
        // Get the symbol names.
        strtab_shndx = this->adjust_shndx(dynsymshdr.get_sh_link());
        if (strtab_shndx >= this->shnum())
  	{
  	  this->error(_("invalid dynamic symbol table name index: %u"),
  		      strtab_shndx);
  	  return;
  	}
        typename This::Shdr strtabshdr(pshdrs + strtab_shndx * This::shdr_size);
        if (strtabshdr.get_sh_type() != elfcpp::SHT_STRTAB)
  	{
  	  this->error(_("dynamic symbol table name section "
  			"has wrong type: %u"),
  		      static_cast<unsigned int>(strtabshdr.get_sh_type()));
  	  return;
  	}
  
        sd->symbol_names = this->get_lasting_view(strtabshdr.get_sh_offset(),
  						strtabshdr.get_sh_size(),
  						false, false);
        sd->symbol_names_size =
  	convert_to_section_size_type(strtabshdr.get_sh_size());
  
        // Get the version information.
  
        unsigned int dummy;
        this->read_dynsym_section(pshdrs, versym_shndx, elfcpp::SHT_GNU_versym,
  				this->dynsym_shndx_,
  				&sd->versym, &sd->versym_size, &dummy);
  
        // We require that the version definition and need section link
        // to the same string table as the dynamic symbol table.  This
        // is not a technical requirement, but it always happens in
        // practice.  We could change this if necessary.
  
        this->read_dynsym_section(pshdrs, verdef_shndx, elfcpp::SHT_GNU_verdef,
  				strtab_shndx, &sd->verdef, &sd->verdef_size,
  				&sd->verdef_info);
  
        this->read_dynsym_section(pshdrs, verneed_shndx, elfcpp::SHT_GNU_verneed,
  				strtab_shndx, &sd->verneed, &sd->verneed_size,
  				&sd->verneed_info);
      }
  
    // Read the SHT_DYNAMIC section to find whether this shared object
    // has a DT_SONAME tag and to record any DT_NEEDED tags.  This
    // doesn't really have anything to do with reading the symbols, but
    // this is a convenient place to do it.
    if (dynamic_shndx != -1U)
      this->read_dynamic(pshdrs, dynamic_shndx, strtab_shndx,
  		       (sd->symbol_names == NULL
  			? NULL
  			: sd->symbol_names->data()),
  		       sd->symbol_names_size);
  }
  
  // Return the Xindex structure to use for object with lots of
  // sections.
  
  template<int size, bool big_endian>
  Xindex*
  Sized_dynobj<size, big_endian>::do_initialize_xindex()
  {
    gold_assert(this->dynsym_shndx_ != -1U);
    Xindex* xindex = new Xindex(this->elf_file_.large_shndx_offset());
    xindex->initialize_symtab_xindex<size, big_endian>(this, this->dynsym_shndx_);
    return xindex;
  }
  
  // Lay out the input sections for a dynamic object.  We don't want to
  // include sections from a dynamic object, so all that we actually do
  // here is check for .gnu.warning and .note.GNU-split-stack sections.
  
  template<int size, bool big_endian>
  void
  Sized_dynobj<size, big_endian>::do_layout(Symbol_table* symtab,
  					  Layout*,
  					  Read_symbols_data* sd)
  {
    const unsigned int shnum = this->shnum();
    if (shnum == 0)
      return;
  
    // Get the section headers.
    const unsigned char* pshdrs = sd->section_headers->data();
  
    // Get the section names.
    const unsigned char* pnamesu = sd->section_names->data();
    const char* pnames = reinterpret_cast<const char*>(pnamesu);
  
    // Skip the first, dummy, section.
    pshdrs += This::shdr_size;
    for (unsigned int i = 1; i < shnum; ++i, pshdrs += This::shdr_size)
      {
        typename This::Shdr shdr(pshdrs);
  
        if (shdr.get_sh_name() >= sd->section_names_size)
  	{
  	  this->error(_("bad section name offset for section %u: %lu"),
  		      i, static_cast<unsigned long>(shdr.get_sh_name()));
  	  return;
  	}
  
        const char* name = pnames + shdr.get_sh_name();
  
        this->handle_gnu_warning_section(name, i, symtab);
        this->handle_split_stack_section(name);
      }
  
    delete sd->section_headers;
    sd->section_headers = NULL;
    delete sd->section_names;
    sd->section_names = NULL;
  }
  
  // Add an entry to the vector mapping version numbers to version
  // strings.
  
  template<int size, bool big_endian>
  void
  Sized_dynobj<size, big_endian>::set_version_map(
      Version_map* version_map,
      unsigned int ndx,
      const char* name) const
  {
    if (ndx >= version_map->size())
      version_map->resize(ndx + 1);
    if ((*version_map)[ndx] != NULL)
      this->error(_("duplicate definition for version %u"), ndx);
    (*version_map)[ndx] = name;
  }
  
  // Add mappings for the version definitions to VERSION_MAP.
  
  template<int size, bool big_endian>
  void
  Sized_dynobj<size, big_endian>::make_verdef_map(
      Read_symbols_data* sd,
      Version_map* version_map) const
  {
    if (sd->verdef == NULL)
      return;
  
    const char* names = reinterpret_cast<const char*>(sd->symbol_names->data());
    section_size_type names_size = sd->symbol_names_size;
  
    const unsigned char* pverdef = sd->verdef->data();
    section_size_type verdef_size = sd->verdef_size;
    const unsigned int count = sd->verdef_info;
  
    const unsigned char* p = pverdef;
    for (unsigned int i = 0; i < count; ++i)
      {
        elfcpp::Verdef<size, big_endian> verdef(p);
  
        if (verdef.get_vd_version() != elfcpp::VER_DEF_CURRENT)
  	{
  	  this->error(_("unexpected verdef version %u"),
  		      verdef.get_vd_version());
  	  return;
  	}
  
        const section_size_type vd_ndx = verdef.get_vd_ndx();
  
        // The GNU linker clears the VERSYM_HIDDEN bit.  I'm not
        // sure why.
  
        // The first Verdaux holds the name of this version.  Subsequent
        // ones are versions that this one depends upon, which we don't
        // care about here.
        const section_size_type vd_cnt = verdef.get_vd_cnt();
        if (vd_cnt < 1)
  	{
  	  this->error(_("verdef vd_cnt field too small: %u"),
                        static_cast<unsigned int>(vd_cnt));
  	  return;
  	}
  
        const section_size_type vd_aux = verdef.get_vd_aux();
        if ((p - pverdef) + vd_aux >= verdef_size)
  	{
  	  this->error(_("verdef vd_aux field out of range: %u"),
                        static_cast<unsigned int>(vd_aux));
  	  return;
  	}
  
        const unsigned char* pvda = p + vd_aux;
        elfcpp::Verdaux<size, big_endian> verdaux(pvda);
  
        const section_size_type vda_name = verdaux.get_vda_name();
        if (vda_name >= names_size)
  	{
  	  this->error(_("verdaux vda_name field out of range: %u"),
                        static_cast<unsigned int>(vda_name));
  	  return;
  	}
  
        this->set_version_map(version_map, vd_ndx, names + vda_name);
  
        const section_size_type vd_next = verdef.get_vd_next();
        if ((p - pverdef) + vd_next >= verdef_size)
  	{
  	  this->error(_("verdef vd_next field out of range: %u"),
                        static_cast<unsigned int>(vd_next));
  	  return;
  	}
  
        p += vd_next;
      }
  }
  
  // Add mappings for the required versions to VERSION_MAP.
  
  template<int size, bool big_endian>
  void
  Sized_dynobj<size, big_endian>::make_verneed_map(
      Read_symbols_data* sd,
      Version_map* version_map) const
  {
    if (sd->verneed == NULL)
      return;
  
    const char* names = reinterpret_cast<const char*>(sd->symbol_names->data());
    section_size_type names_size = sd->symbol_names_size;
  
    const unsigned char* pverneed = sd->verneed->data();
    const section_size_type verneed_size = sd->verneed_size;
    const unsigned int count = sd->verneed_info;
  
    const unsigned char* p = pverneed;
    for (unsigned int i = 0; i < count; ++i)
      {
        elfcpp::Verneed<size, big_endian> verneed(p);
  
        if (verneed.get_vn_version() != elfcpp::VER_NEED_CURRENT)
  	{
  	  this->error(_("unexpected verneed version %u"),
  		      verneed.get_vn_version());
  	  return;
  	}
  
        const section_size_type vn_aux = verneed.get_vn_aux();
  
        if ((p - pverneed) + vn_aux >= verneed_size)
  	{
  	  this->error(_("verneed vn_aux field out of range: %u"),
                        static_cast<unsigned int>(vn_aux));
  	  return;
  	}
  
        const unsigned int vn_cnt = verneed.get_vn_cnt();
        const unsigned char* pvna = p + vn_aux;
        for (unsigned int j = 0; j < vn_cnt; ++j)
  	{
  	  elfcpp::Vernaux<size, big_endian> vernaux(pvna);
  
  	  const unsigned int vna_name = vernaux.get_vna_name();
  	  if (vna_name >= names_size)
  	    {
  	      this->error(_("vernaux vna_name field out of range: %u"),
  			  static_cast<unsigned int>(vna_name));
  	      return;
  	    }
  
  	  this->set_version_map(version_map, vernaux.get_vna_other(),
  				names + vna_name);
  
  	  const section_size_type vna_next = vernaux.get_vna_next();
  	  if ((pvna - pverneed) + vna_next >= verneed_size)
  	    {
  	      this->error(_("verneed vna_next field out of range: %u"),
  			  static_cast<unsigned int>(vna_next));
  	      return;
  	    }
  
  	  pvna += vna_next;
  	}
  
        const section_size_type vn_next = verneed.get_vn_next();
        if ((p - pverneed) + vn_next >= verneed_size)
  	{
  	  this->error(_("verneed vn_next field out of range: %u"),
                        static_cast<unsigned int>(vn_next));
  	  return;
  	}
  
        p += vn_next;
      }
  }
  
  // Create a vector mapping version numbers to version strings.
  
  template<int size, bool big_endian>
  void
  Sized_dynobj<size, big_endian>::make_version_map(
      Read_symbols_data* sd,
      Version_map* version_map) const
  {
    if (sd->verdef == NULL && sd->verneed == NULL)
      return;
  
    // A guess at the maximum version number we will see.  If this is
    // wrong we will be less efficient but still correct.
    version_map->reserve(sd->verdef_info + sd->verneed_info * 10);
  
    this->make_verdef_map(sd, version_map);
    this->make_verneed_map(sd, version_map);
  }
  
  // Add the dynamic symbols to the symbol table.
  
  template<int size, bool big_endian>
  void
  Sized_dynobj<size, big_endian>::do_add_symbols(Symbol_table* symtab,
  					       Read_symbols_data* sd,
  					       Layout*)
  {
    if (sd->symbols == NULL)
      {
        gold_assert(sd->symbol_names == NULL);
        gold_assert(sd->versym == NULL && sd->verdef == NULL
  		  && sd->verneed == NULL);
        return;
      }
  
    const int sym_size = This::sym_size;
    const size_t symcount = sd->symbols_size / sym_size;
    gold_assert(sd->external_symbols_offset == 0);
    if (symcount * sym_size != sd->symbols_size)
      {
        this->error(_("size of dynamic symbols is not multiple of symbol size"));
        return;
      }
  
    Version_map version_map;
    this->make_version_map(sd, &version_map);
  
    // If printing symbol counts or a cross reference table, we want to
    // track symbols.
    if (parameters->options().user_set_print_symbol_counts()
        || parameters->options().cref())
      {
        this->symbols_ = new Symbols();
        this->symbols_->resize(symcount);
      }
  
    const char* sym_names =
      reinterpret_cast<const char*>(sd->symbol_names->data());
    symtab->add_from_dynobj(this, sd->symbols->data(), symcount,
  			  sym_names, sd->symbol_names_size,
  			  (sd->versym == NULL
  			   ? NULL
  			   : sd->versym->data()),
  			  sd->versym_size,
  			  &version_map,
  			  this->symbols_,
  			  &this->defined_count_);
  
    delete sd->symbols;
    sd->symbols = NULL;
    delete sd->symbol_names;
    sd->symbol_names = NULL;
    if (sd->versym != NULL)
      {
        delete sd->versym;
        sd->versym = NULL;
      }
    if (sd->verdef != NULL)
      {
        delete sd->verdef;
        sd->verdef = NULL;
      }
    if (sd->verneed != NULL)
      {
        delete sd->verneed;
        sd->verneed = NULL;
      }
  
    // This is normally the last time we will read any data from this
    // file.
    this->clear_view_cache_marks();
  }
  
  template<int size, bool big_endian>
  Archive::Should_include
  Sized_dynobj<size, big_endian>::do_should_include_member(Symbol_table*,
  							 Layout*,
  							 Read_symbols_data*,
  							 std::string*)
  {
    return Archive::SHOULD_INCLUDE_YES;
  }
  
  // Get symbol counts.
  
  template<int size, bool big_endian>
  void
  Sized_dynobj<size, big_endian>::do_get_global_symbol_counts(
      const Symbol_table*,
      size_t* defined,
      size_t* used) const
  {
    *defined = this->defined_count_;
    size_t count = 0;
    for (typename Symbols::const_iterator p = this->symbols_->begin();
         p != this->symbols_->end();
         ++p)
      if (*p != NULL
  	&& (*p)->source() == Symbol::FROM_OBJECT
  	&& (*p)->object() == this
  	&& (*p)->is_defined()
  	&& (*p)->dynsym_index() != -1U)
        ++count;
    *used = count;
  }
  
  // Given a vector of hash codes, compute the number of hash buckets to
  // use.
  
  unsigned int
  Dynobj::compute_bucket_count(const std::vector<uint32_t>& hashcodes,
  			     bool for_gnu_hash_table)
  {
    // FIXME: Implement optional hash table optimization.
  
    // Array used to determine the number of hash table buckets to use
    // based on the number of symbols there are.  If there are fewer
    // than 3 symbols we use 1 bucket, fewer than 17 symbols we use 3
    // buckets, fewer than 37 we use 17 buckets, and so forth.  We never
    // use more than 262147 buckets.  This is straight from the old GNU
    // linker.
    static const unsigned int buckets[] =
    {
      1, 3, 17, 37, 67, 97, 131, 197, 263, 521, 1031, 2053, 4099, 8209,
      16411, 32771, 65537, 131101, 262147
    };
    const int buckets_count = sizeof buckets / sizeof buckets[0];
  
    unsigned int symcount = hashcodes.size();
    unsigned int ret = 1;
    const double full_fraction
      = 1.0 - parameters->options().hash_bucket_empty_fraction();
    for (int i = 0; i < buckets_count; ++i)
      {
        if (symcount < buckets[i] * full_fraction)
  	break;
        ret = buckets[i];
      }
  
    if (for_gnu_hash_table && ret < 2)
      ret = 2;
  
    return ret;
  }
  
  // The standard ELF hash function.  This hash function must not
  // change, as the dynamic linker uses it also.
  
  uint32_t
  Dynobj::elf_hash(const char* name)
  {
    const unsigned char* nameu = reinterpret_cast<const unsigned char*>(name);
    uint32_t h = 0;
    unsigned char c;
    while ((c = *nameu++) != '\0')
      {
        h = (h << 4) + c;
        uint32_t g = h & 0xf0000000;
        if (g != 0)
  	{
  	  h ^= g >> 24;
  	  // The ELF ABI says h &= ~g, but using xor is equivalent in
  	  // this case (since g was set from h) and may save one
  	  // instruction.
  	  h ^= g;
  	}
      }
    return h;
  }
  
  // Create a standard ELF hash table, setting *PPHASH and *PHASHLEN.
  // DYNSYMS is a vector with all the global dynamic symbols.
  // LOCAL_DYNSYM_COUNT is the number of local symbols in the dynamic
  // symbol table.
  
  void
  Dynobj::create_elf_hash_table(const std::vector<Symbol*>& dynsyms,
  			      unsigned int local_dynsym_count,
  			      unsigned char** pphash,
  			      unsigned int* phashlen)
  {
    unsigned int dynsym_count = dynsyms.size();
  
    // Get the hash values for all the symbols.
    std::vector<uint32_t> dynsym_hashvals(dynsym_count);
    for (unsigned int i = 0; i < dynsym_count; ++i)
      dynsym_hashvals[i] = Dynobj::elf_hash(dynsyms[i]->name());
  
    const unsigned int bucketcount =
      Dynobj::compute_bucket_count(dynsym_hashvals, false);
  
    std::vector<uint32_t> bucket(bucketcount);
    std::vector<uint32_t> chain(local_dynsym_count + dynsym_count);
  
    for (unsigned int i = 0; i < dynsym_count; ++i)
      {
        unsigned int dynsym_index = dynsyms[i]->dynsym_index();
        unsigned int bucketpos = dynsym_hashvals[i] % bucketcount;
        chain[dynsym_index] = bucket[bucketpos];
        bucket[bucketpos] = dynsym_index;
      }
  
    unsigned int hashlen = ((2
  			   + bucketcount
  			   + local_dynsym_count
  			   + dynsym_count)
  			  * 4);
    unsigned char* phash = new unsigned char[hashlen];
  
    if (parameters->target().is_big_endian())
      {
  #if defined(HAVE_TARGET_32_BIG) || defined(HAVE_TARGET_64_BIG)
        Dynobj::sized_create_elf_hash_table<true>(bucket, chain, phash,
  						hashlen);
  #else
        gold_unreachable();
  #endif
      }
    else
      {
  #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_64_LITTLE)
        Dynobj::sized_create_elf_hash_table<false>(bucket, chain, phash,
  						 hashlen);
  #else
        gold_unreachable();
  #endif
      }
  
    *pphash = phash;
    *phashlen = hashlen;
  }
  
  // Fill in an ELF hash table.
  
  template<bool big_endian>
  void
  Dynobj::sized_create_elf_hash_table(const std::vector<uint32_t>& bucket,
  				    const std::vector<uint32_t>& chain,
  				    unsigned char* phash,
  				    unsigned int hashlen)
  {
    unsigned char* p = phash;
  
    const unsigned int bucketcount = bucket.size();
    const unsigned int chaincount = chain.size();
  
    elfcpp::Swap<32, big_endian>::writeval(p, bucketcount);
    p += 4;
    elfcpp::Swap<32, big_endian>::writeval(p, chaincount);
    p += 4;
  
    for (unsigned int i = 0; i < bucketcount; ++i)
      {
        elfcpp::Swap<32, big_endian>::writeval(p, bucket[i]);
        p += 4;
      }
  
    for (unsigned int i = 0; i < chaincount; ++i)
      {
        elfcpp::Swap<32, big_endian>::writeval(p, chain[i]);
        p += 4;
      }
  
    gold_assert(static_cast<unsigned int>(p - phash) == hashlen);
  }
  
  // The hash function used for the GNU hash table.  This hash function
  // must not change, as the dynamic linker uses it also.
  
  uint32_t
  Dynobj::gnu_hash(const char* name)
  {
    const unsigned char* nameu = reinterpret_cast<const unsigned char*>(name);
    uint32_t h = 5381;
    unsigned char c;
    while ((c = *nameu++) != '\0')
      h = (h << 5) + h + c;
    return h;
  }
  
  // Create a GNU hash table, setting *PPHASH and *PHASHLEN.  GNU hash
  // tables are an extension to ELF which are recognized by the GNU
  // dynamic linker.  They are referenced using dynamic tag DT_GNU_HASH.
  // TARGET is the target.  DYNSYMS is a vector with all the global
  // symbols which will be going into the dynamic symbol table.
  // LOCAL_DYNSYM_COUNT is the number of local symbols in the dynamic
  // symbol table.
  
  void
  Dynobj::create_gnu_hash_table(const std::vector<Symbol*>& dynsyms,
  			      unsigned int local_dynsym_count,
  			      unsigned char** pphash,
  			      unsigned int* phashlen)
  {
    const unsigned int count = dynsyms.size();
  
    // Sort the dynamic symbols into two vectors.  Symbols which we do
    // not want to put into the hash table we store into
    // UNHASHED_DYNSYMS.  Symbols which we do want to store we put into
    // HASHED_DYNSYMS.  DYNSYM_HASHVALS is parallel to HASHED_DYNSYMS,
    // and records the hash codes.
  
    std::vector<Symbol*> unhashed_dynsyms;
    unhashed_dynsyms.reserve(count);
  
    std::vector<Symbol*> hashed_dynsyms;
    hashed_dynsyms.reserve(count);
  
    std::vector<uint32_t> dynsym_hashvals;
    dynsym_hashvals.reserve(count);
    
    for (unsigned int i = 0; i < count; ++i)
      {
        Symbol* sym = dynsyms[i];
  
        if (!sym->needs_dynsym_value()
  	  && (sym->is_undefined()
  	      || sym->is_from_dynobj()
  	      || sym->is_forced_local()))
  	unhashed_dynsyms.push_back(sym);
        else
  	{
  	  hashed_dynsyms.push_back(sym);
  	  dynsym_hashvals.push_back(Dynobj::gnu_hash(sym->name()));
  	}
      }
  
    // Put the unhashed symbols at the start of the global portion of
    // the dynamic symbol table.
    const unsigned int unhashed_count = unhashed_dynsyms.size();
    unsigned int unhashed_dynsym_index = local_dynsym_count;
    for (unsigned int i = 0; i < unhashed_count; ++i)
      {
        unhashed_dynsyms[i]->set_dynsym_index(unhashed_dynsym_index);
        ++unhashed_dynsym_index;
      }
  
    // For the actual data generation we call out to a templatized
    // function.
    int size = parameters->target().get_size();
    bool big_endian = parameters->target().is_big_endian();
    if (size == 32)
      {
        if (big_endian)
  	{
  #ifdef HAVE_TARGET_32_BIG
  	  Dynobj::sized_create_gnu_hash_table<32, true>(hashed_dynsyms,
  							dynsym_hashvals,
  							unhashed_dynsym_index,
  							pphash,
  							phashlen);
  #else
  	  gold_unreachable();
  #endif
  	}
        else
  	{
  #ifdef HAVE_TARGET_32_LITTLE
  	  Dynobj::sized_create_gnu_hash_table<32, false>(hashed_dynsyms,
  							 dynsym_hashvals,
  							 unhashed_dynsym_index,
  							 pphash,
  							 phashlen);
  #else
  	  gold_unreachable();
  #endif
  	}
      }
    else if (size == 64)
      {
        if (big_endian)
  	{
  #ifdef HAVE_TARGET_64_BIG
  	  Dynobj::sized_create_gnu_hash_table<64, true>(hashed_dynsyms,
  							dynsym_hashvals,
  							unhashed_dynsym_index,
  							pphash,
  							phashlen);
  #else
  	  gold_unreachable();
  #endif
  	}
        else
  	{
  #ifdef HAVE_TARGET_64_LITTLE
  	  Dynobj::sized_create_gnu_hash_table<64, false>(hashed_dynsyms,
  							 dynsym_hashvals,
  							 unhashed_dynsym_index,
  							 pphash,
  							 phashlen);
  #else
  	  gold_unreachable();
  #endif
  	}
      }
    else
      gold_unreachable();
  }
  
  // Create the actual data for a GNU hash table.  This is just a copy
  // of the code from the old GNU linker.
  
  template<int size, bool big_endian>
  void
  Dynobj::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)
  {
    if (hashed_dynsyms.empty())
      {
        // Special case for the empty hash table.
        unsigned int hashlen = 5 * 4 + size / 8;
        unsigned char* phash = new unsigned char[hashlen];
        // One empty bucket.
        elfcpp::Swap<32, big_endian>::writeval(phash, 1);
        // Symbol index above unhashed symbols.
        elfcpp::Swap<32, big_endian>::writeval(phash + 4, unhashed_dynsym_count);
        // One word for bitmask.
        elfcpp::Swap<32, big_endian>::writeval(phash + 8, 1);
        // Only bloom filter.
        elfcpp::Swap<32, big_endian>::writeval(phash + 12, 0);
        // No valid hashes.
        elfcpp::Swap<size, big_endian>::writeval(phash + 16, 0);
        // No hashes in only bucket.
        elfcpp::Swap<32, big_endian>::writeval(phash + 16 + size / 8, 0);
  
        *phashlen = hashlen;
        *pphash = phash;
  
        return;
      }
  
    const unsigned int bucketcount =
      Dynobj::compute_bucket_count(dynsym_hashvals, true);
  
    const unsigned int nsyms = hashed_dynsyms.size();
  
    uint32_t maskbitslog2 = 1;
    uint32_t x = nsyms >> 1;
    while (x != 0)
      {
        ++maskbitslog2;
        x >>= 1;
      }
    if (maskbitslog2 < 3)
      maskbitslog2 = 5;
    else if (((1U << (maskbitslog2 - 2)) & nsyms) != 0)
      maskbitslog2 += 3;
    else
      maskbitslog2 += 2;
  
    uint32_t shift1;
    if (size == 32)
      shift1 = 5;
    else
      {
        if (maskbitslog2 == 5)
  	maskbitslog2 = 6;
        shift1 = 6;
      }
    uint32_t mask = (1U << shift1) - 1U;
    uint32_t shift2 = maskbitslog2;
    uint32_t maskbits = 1U << maskbitslog2;
    uint32_t maskwords = 1U << (maskbitslog2 - shift1);
  
    typedef typename elfcpp::Elf_types<size>::Elf_WXword Word;
    std::vector<Word> bitmask(maskwords);
    std::vector<uint32_t> counts(bucketcount);
    std::vector<uint32_t> indx(bucketcount);
    uint32_t symindx = unhashed_dynsym_count;
  
    // Count the number of times each hash bucket is used.
    for (unsigned int i = 0; i < nsyms; ++i)
      ++counts[dynsym_hashvals[i] % bucketcount];
  
    unsigned int cnt = symindx;
    for (unsigned int i = 0; i < bucketcount; ++i)
      {
        indx[i] = cnt;
        cnt += counts[i];
      }
  
    unsigned int hashlen = (4 + bucketcount + nsyms) * 4;
    hashlen += maskbits / 8;
    unsigned char* phash = new unsigned char[hashlen];
  
    elfcpp::Swap<32, big_endian>::writeval(phash, bucketcount);
    elfcpp::Swap<32, big_endian>::writeval(phash + 4, symindx);
    elfcpp::Swap<32, big_endian>::writeval(phash + 8, maskwords);
    elfcpp::Swap<32, big_endian>::writeval(phash + 12, shift2);
  
    unsigned char* p = phash + 16 + maskbits / 8;
    for (unsigned int i = 0; i < bucketcount; ++i)
      {
        if (counts[i] == 0)
  	elfcpp::Swap<32, big_endian>::writeval(p, 0);
        else
  	elfcpp::Swap<32, big_endian>::writeval(p, indx[i]);
        p += 4;
      }
  
    for (unsigned int i = 0; i < nsyms; ++i)
      {
        Symbol* sym = hashed_dynsyms[i];
        uint32_t hashval = dynsym_hashvals[i];
  
        unsigned int bucket = hashval % bucketcount;
        unsigned int val = ((hashval >> shift1)
  			  & ((maskbits >> shift1) - 1));
        bitmask[val] |= (static_cast<Word>(1U)) << (hashval & mask);
        bitmask[val] |= (static_cast<Word>(1U)) << ((hashval >> shift2) & mask);
        val = hashval & ~ 1U;
        if (counts[bucket] == 1)
  	{
  	  // Last element terminates the chain.
  	  val |= 1;
  	}
        elfcpp::Swap<32, big_endian>::writeval(p + (indx[bucket] - symindx) * 4,
  					     val);
        --counts[bucket];
  
        sym->set_dynsym_index(indx[bucket]);
        ++indx[bucket];
      }
  
    p = phash + 16;
    for (unsigned int i = 0; i < maskwords; ++i)
      {
        elfcpp::Swap<size, big_endian>::writeval(p, bitmask[i]);
        p += size / 8;
      }
  
    *phashlen = hashlen;
    *pphash = phash;
  }
  
  // Verdef methods.
  
  // Write this definition to a buffer for the output section.
  
  template<int size, bool big_endian>
  unsigned char*
  Verdef::write(const Stringpool* dynpool, bool is_last, unsigned char* pb) const
  {
    const int verdef_size = elfcpp::Elf_sizes<size>::verdef_size;
    const int verdaux_size = elfcpp::Elf_sizes<size>::verdaux_size;
  
    elfcpp::Verdef_write<size, big_endian> vd(pb);
    vd.set_vd_version(elfcpp::VER_DEF_CURRENT);
    vd.set_vd_flags((this->is_base_ ? elfcpp::VER_FLG_BASE : 0)
  		  | (this->is_weak_ ? elfcpp::VER_FLG_WEAK : 0)
  		  | (this->is_info_ ? elfcpp::VER_FLG_INFO : 0));
    vd.set_vd_ndx(this->index());
    vd.set_vd_cnt(1 + this->deps_.size());
    vd.set_vd_hash(Dynobj::elf_hash(this->name()));
    vd.set_vd_aux(verdef_size);
    vd.set_vd_next(is_last
  		 ? 0
  		 : verdef_size + (1 + this->deps_.size()) * verdaux_size);
    pb += verdef_size;
  
    elfcpp::Verdaux_write<size, big_endian> vda(pb);
    vda.set_vda_name(dynpool->get_offset(this->name()));
    vda.set_vda_next(this->deps_.empty() ? 0 : verdaux_size);
    pb += verdaux_size;
  
    Deps::const_iterator p;
    unsigned int i;
    for (p = this->deps_.begin(), i = 0;
         p != this->deps_.end();
         ++p, ++i)
      {
        elfcpp::Verdaux_write<size, big_endian> vda(pb);
        vda.set_vda_name(dynpool->get_offset(*p));
        vda.set_vda_next(i + 1 >= this->deps_.size() ? 0 : verdaux_size);
        pb += verdaux_size;
      }
  
    return pb;
  }
  
  // Verneed methods.
  
  Verneed::~Verneed()
  {
    for (Need_versions::iterator p = this->need_versions_.begin();
         p != this->need_versions_.end();
         ++p)
      delete *p;
  }
  
  // Add a new version to this file reference.
  
  Verneed_version*
  Verneed::add_name(const char* name)
  {
    Verneed_version* vv = new Verneed_version(name);
    this->need_versions_.push_back(vv);
    return vv;
  }
  
  // Set the version indexes starting at INDEX.
  
  unsigned int
  Verneed::finalize(unsigned int index)
  {
    for (Need_versions::iterator p = this->need_versions_.begin();
         p != this->need_versions_.end();
         ++p)
      {
        (*p)->set_index(index);
        ++index;
      }
    return index;
  }
  
  // Write this list of referenced versions to a buffer for the output
  // section.
  
  template<int size, bool big_endian>
  unsigned char*
  Verneed::write(const Stringpool* dynpool, bool is_last,
  	       unsigned char* pb) const
  {
    const int verneed_size = elfcpp::Elf_sizes<size>::verneed_size;
    const int vernaux_size = elfcpp::Elf_sizes<size>::vernaux_size;
  
    elfcpp::Verneed_write<size, big_endian> vn(pb);
    vn.set_vn_version(elfcpp::VER_NEED_CURRENT);
    vn.set_vn_cnt(this->need_versions_.size());
    vn.set_vn_file(dynpool->get_offset(this->filename()));
    vn.set_vn_aux(verneed_size);
    vn.set_vn_next(is_last
  		 ? 0
  		 : verneed_size + this->need_versions_.size() * vernaux_size);
    pb += verneed_size;
  
    Need_versions::const_iterator p;
    unsigned int i;
    for (p = this->need_versions_.begin(), i = 0;
         p != this->need_versions_.end();
         ++p, ++i)
      {
        elfcpp::Vernaux_write<size, big_endian> vna(pb);
        vna.set_vna_hash(Dynobj::elf_hash((*p)->version()));
        // FIXME: We need to sometimes set VER_FLG_WEAK here.
        vna.set_vna_flags(0);
        vna.set_vna_other((*p)->index());
        vna.set_vna_name(dynpool->get_offset((*p)->version()));
        vna.set_vna_next(i + 1 >= this->need_versions_.size()
  		       ? 0
  		       : vernaux_size);
        pb += vernaux_size;
      }
  
    return pb;
  }
  
  // Versions methods.
  
  Versions::Versions(const Version_script_info& version_script,
                     Stringpool* dynpool)
    : defs_(), needs_(), version_table_(),
      is_finalized_(false), version_script_(version_script),
      needs_base_version_(parameters->options().shared())
  {
    if (!this->version_script_.empty())
      {
        // Parse the version script, and insert each declared version into
        // defs_ and version_table_.
        std::vector<std::string> versions = this->version_script_.get_versions();
  
        if (this->needs_base_version_ && !versions.empty())
  	this->define_base_version(dynpool);
  
        for (size_t k = 0; k < versions.size(); ++k)
          {
            Stringpool::Key version_key;
            const char* version = dynpool->add(versions[k].c_str(),
                                               true, &version_key);
            Verdef* const vd = new Verdef(
                version,
                this->version_script_.get_dependencies(version),
                false, false, false, false);
            this->defs_.push_back(vd);
            Key key(version_key, 0);
            this->version_table_.insert(std::make_pair(key, vd));
          }
      }
  }
  
  Versions::~Versions()
  {
    for (Defs::iterator p = this->defs_.begin();
         p != this->defs_.end();
         ++p)
      delete *p;
  
    for (Needs::iterator p = this->needs_.begin();
         p != this->needs_.end();
         ++p)
      delete *p;
  }
  
  // Define the base version of a shared library.  The base version definition
  // must be the first entry in defs_.  We insert it lazily so that defs_ is
  // empty if no symbol versioning is used.  Then layout can just drop the
  // version sections.
  
  void
  Versions::define_base_version(Stringpool* dynpool)
  {
    // If we do any versioning at all,  we always need a base version, so
    // define that first.  Nothing explicitly declares itself as part of base,
    // so it doesn't need to be in version_table_.
    gold_assert(this->defs_.empty());
    const char* name = parameters->options().soname();
    if (name == NULL)
      name = parameters->options().output_file_name();
    name = dynpool->add(name, false, NULL);
    Verdef* vdbase = new Verdef(name, std::vector<std::string>(),
                                true, false, false, true);
    this->defs_.push_back(vdbase);
    this->needs_base_version_ = false;
  }
  
  // Return the dynamic object which a symbol refers to.
  
  Dynobj*
  Versions::get_dynobj_for_sym(const Symbol_table* symtab,
  			     const Symbol* sym) const
  {
    if (sym->is_copied_from_dynobj())
      return symtab->get_copy_source(sym);
    else
      {
        Object* object = sym->object();
        gold_assert(object->is_dynamic());
        return static_cast<Dynobj*>(object);
      }
  }
  
  // Record version information for a symbol going into the dynamic
  // symbol table.
  
  void
  Versions::record_version(const Symbol_table* symtab,
  			 Stringpool* dynpool, const Symbol* sym)
  {
    gold_assert(!this->is_finalized_);
    gold_assert(sym->version() != NULL);
  
    Stringpool::Key version_key;
    const char* version = dynpool->add(sym->version(), false, &version_key);
  
    if (!sym->is_from_dynobj() && !sym->is_copied_from_dynobj())
      {
        if (parameters->options().shared())
          this->add_def(sym, version, version_key);
      }
    else
      {
        // This is a version reference.
        Dynobj* dynobj = this->get_dynobj_for_sym(symtab, sym);
        this->add_need(dynpool, dynobj->soname(), version, version_key);
      }
  }
  
  // We've found a symbol SYM defined in version VERSION.
  
  void
  Versions::add_def(const Symbol* sym, const char* version,
  		  Stringpool::Key version_key)
  {
    Key k(version_key, 0);
    Version_base* const vbnull = NULL;
    std::pair<Version_table::iterator, bool> ins =
      this->version_table_.insert(std::make_pair(k, vbnull));
  
    if (!ins.second)
      {
        // We already have an entry for this version.
        Version_base* vb = ins.first->second;
  
        // We have now seen a symbol in this version, so it is not
        // weak.
        gold_assert(vb != NULL);
        vb->clear_weak();
      }
    else
      {
        // If we are creating a shared object, it is an error to
        // find a definition of a symbol with a version which is not
        // in the version script.
        if (parameters->options().shared())
  	gold_error(_("symbol %s has undefined version %s"),
  		   sym->demangled_name().c_str(), version);
        else
  	// We only insert a base version for shared library.
  	gold_assert(!this->needs_base_version_);
  	
        // When creating a regular executable, automatically define
        // a new version.
        Verdef* vd = new Verdef(version, std::vector<std::string>(),
                                false, false, false, false);
        this->defs_.push_back(vd);
        ins.first->second = vd;
      }
  }
  
  // Add a reference to version NAME in file FILENAME.
  
  void
  Versions::add_need(Stringpool* dynpool, const char* filename, const char* name,
  		   Stringpool::Key name_key)
  {
    Stringpool::Key filename_key;
    filename = dynpool->add(filename, true, &filename_key);
  
    Key k(name_key, filename_key);
    Version_base* const vbnull = NULL;
    std::pair<Version_table::iterator, bool> ins =
      this->version_table_.insert(std::make_pair(k, vbnull));
  
    if (!ins.second)
      {
        // We already have an entry for this filename/version.
        return;
      }
  
    // See whether we already have this filename.  We don't expect many
    // version references, so we just do a linear search.  This could be
    // replaced by a hash table.
    Verneed* vn = NULL;
    for (Needs::iterator p = this->needs_.begin();
         p != this->needs_.end();
         ++p)
      {
        if ((*p)->filename() == filename)
  	{
  	  vn = *p;
  	  break;
  	}
      }
  
    if (vn == NULL)
      {
        // Create base version definition lazily for shared library.
        if (this->needs_base_version_)
  	this->define_base_version(dynpool);
  
        // We have a new filename.
        vn = new Verneed(filename);
        this->needs_.push_back(vn);
      }
  
    ins.first->second = vn->add_name(name);
  }
  
  // Set the version indexes.  Create a new dynamic version symbol for
  // each new version definition.
  
  unsigned int
  Versions::finalize(Symbol_table* symtab, unsigned int dynsym_index,
  		   std::vector<Symbol*>* syms)
  {
    gold_assert(!this->is_finalized_);
  
    unsigned int vi = 1;
  
    for (Defs::iterator p = this->defs_.begin();
         p != this->defs_.end();
         ++p)
      {
        (*p)->set_index(vi);
        ++vi;
  
        // Create a version symbol if necessary.
        if (!(*p)->is_symbol_created())
  	{
  	  Symbol* vsym = symtab->define_as_constant((*p)->name(),
  						    (*p)->name(),
  						    Symbol_table::PREDEFINED,
  						    0, 0,
  						    elfcpp::STT_OBJECT,
  						    elfcpp::STB_GLOBAL,
  						    elfcpp::STV_DEFAULT, 0,
  						    false, false);
  	  vsym->set_needs_dynsym_entry();
            vsym->set_dynsym_index(dynsym_index);
  	  vsym->set_is_default();
  	  ++dynsym_index;
  	  syms->push_back(vsym);
  	  // The name is already in the dynamic pool.
  	}
      }
  
    // Index 1 is used for global symbols.
    if (vi == 1)
      {
        gold_assert(this->defs_.empty());
        vi = 2;
      }
  
    for (Needs::iterator p = this->needs_.begin();
         p != this->needs_.end();
         ++p)
      vi = (*p)->finalize(vi);
  
    this->is_finalized_ = true;
  
    return dynsym_index;
  }
  
  // Return the version index to use for a symbol.  This does two hash
  // table lookups: one in DYNPOOL and one in this->version_table_.
  // Another approach alternative would be store a pointer in SYM, which
  // would increase the size of the symbol table.  Or perhaps we could
  // use a hash table from dynamic symbol pointer values to Version_base
  // pointers.
  
  unsigned int
  Versions::version_index(const Symbol_table* symtab, const Stringpool* dynpool,
  			const Symbol* sym) const
  {
    Stringpool::Key version_key;
    const char* version = dynpool->find(sym->version(), &version_key);
    gold_assert(version != NULL);
  
    Key k;
    if (!sym->is_from_dynobj() && !sym->is_copied_from_dynobj())
      {
        if (!parameters->options().shared())
          return elfcpp::VER_NDX_GLOBAL;
        k = Key(version_key, 0);
      }
    else
      {
        Dynobj* dynobj = this->get_dynobj_for_sym(symtab, sym);
  
        Stringpool::Key filename_key;
        const char* filename = dynpool->find(dynobj->soname(), &filename_key);
        gold_assert(filename != NULL);
  
        k = Key(version_key, filename_key);
      }
  
    Version_table::const_iterator p = this->version_table_.find(k);
    gold_assert(p != this->version_table_.end());
  
    return p->second->index();
  }
  
  // Return an allocated buffer holding the contents of the symbol
  // version section.
  
  template<int size, bool big_endian>
  void
  Versions::symbol_section_contents(const Symbol_table* symtab,
  				  const Stringpool* dynpool,
  				  unsigned int local_symcount,
  				  const std::vector<Symbol*>& syms,
  				  unsigned char** pp,
  				  unsigned int* psize) const
  {
    gold_assert(this->is_finalized_);
  
    unsigned int sz = (local_symcount + syms.size()) * 2;
    unsigned char* pbuf = new unsigned char[sz];
  
    for (unsigned int i = 0; i < local_symcount; ++i)
      elfcpp::Swap<16, big_endian>::writeval(pbuf + i * 2,
  					   elfcpp::VER_NDX_LOCAL);
  
    for (std::vector<Symbol*>::const_iterator p = syms.begin();
         p != syms.end();
         ++p)
      {
        unsigned int version_index;
        const char* version = (*p)->version();
        if (version != NULL)
  	version_index = this->version_index(symtab, dynpool, *p);
        else
  	{
  	  if ((*p)->is_defined() && !(*p)->is_from_dynobj())
  	    version_index = elfcpp::VER_NDX_GLOBAL;
  	  else
  	    version_index = elfcpp::VER_NDX_LOCAL;
  	}
        // If the symbol was defined as foo@V1 instead of foo@@V1, add
        // the hidden bit.
        if ((*p)->version() != NULL && !(*p)->is_default())
          version_index |= elfcpp::VERSYM_HIDDEN;
        elfcpp::Swap<16, big_endian>::writeval(pbuf + (*p)->dynsym_index() * 2,
                                               version_index);
      }
  
    *pp = pbuf;
    *psize = sz;
  }
  
  // Return an allocated buffer holding the contents of the version
  // definition section.
  
  template<int size, bool big_endian>
  void
  Versions::def_section_contents(const Stringpool* dynpool,
  			       unsigned char** pp, unsigned int* psize,
  			       unsigned int* pentries) const
  {
    gold_assert(this->is_finalized_);
    gold_assert(!this->defs_.empty());
  
    const int verdef_size = elfcpp::Elf_sizes<size>::verdef_size;
    const int verdaux_size = elfcpp::Elf_sizes<size>::verdaux_size;
  
    unsigned int sz = 0;
    for (Defs::const_iterator p = this->defs_.begin();
         p != this->defs_.end();
         ++p)
      {
        sz += verdef_size + verdaux_size;
        sz += (*p)->count_dependencies() * verdaux_size;
      }
  
    unsigned char* pbuf = new unsigned char[sz];
  
    unsigned char* pb = pbuf;
    Defs::const_iterator p;
    unsigned int i;
    for (p = this->defs_.begin(), i = 0;
         p != this->defs_.end();
         ++p, ++i)
      pb = (*p)->write<size, big_endian>(dynpool,
  				       i + 1 >= this->defs_.size(),
  				       pb);
  
    gold_assert(static_cast<unsigned int>(pb - pbuf) == sz);
  
    *pp = pbuf;
    *psize = sz;
    *pentries = this->defs_.size();
  }
  
  // Return an allocated buffer holding the contents of the version
  // reference section.
  
  template<int size, bool big_endian>
  void
  Versions::need_section_contents(const Stringpool* dynpool,
  				unsigned char** pp, unsigned int* psize,
  				unsigned int* pentries) const
  {
    gold_assert(this->is_finalized_);
    gold_assert(!this->needs_.empty());
  
    const int verneed_size = elfcpp::Elf_sizes<size>::verneed_size;
    const int vernaux_size = elfcpp::Elf_sizes<size>::vernaux_size;
  
    unsigned int sz = 0;
    for (Needs::const_iterator p = this->needs_.begin();
         p != this->needs_.end();
         ++p)
      {
        sz += verneed_size;
        sz += (*p)->count_versions() * vernaux_size;
      }
  
    unsigned char* pbuf = new unsigned char[sz];
  
    unsigned char* pb = pbuf;
    Needs::const_iterator p;
    unsigned int i;
    for (p = this->needs_.begin(), i = 0;
         p != this->needs_.end();
         ++p, ++i)
      pb = (*p)->write<size, big_endian>(dynpool,
  				       i + 1 >= this->needs_.size(),
  				       pb);
  
    gold_assert(static_cast<unsigned int>(pb - pbuf) == sz);
  
    *pp = pbuf;
    *psize = sz;
    *pentries = this->needs_.size();
  }
  
  // Instantiate the templates we need.  We could use the configure
  // script to restrict this to only the ones for implemented targets.
  
  #ifdef HAVE_TARGET_32_LITTLE
  template
  class Sized_dynobj<32, false>;
  #endif
  
  #ifdef HAVE_TARGET_32_BIG
  template
  class Sized_dynobj<32, true>;
  #endif
  
  #ifdef HAVE_TARGET_64_LITTLE
  template
  class Sized_dynobj<64, false>;
  #endif
  
  #ifdef HAVE_TARGET_64_BIG
  template
  class Sized_dynobj<64, true>;
  #endif
  
  #ifdef HAVE_TARGET_32_LITTLE
  template
  void
  Versions::symbol_section_contents<32, false>(
      const Symbol_table*,
      const Stringpool*,
      unsigned int,
      const std::vector<Symbol*>&,
      unsigned char**,
      unsigned int*) const;
  #endif
  
  #ifdef HAVE_TARGET_32_BIG
  template
  void
  Versions::symbol_section_contents<32, true>(
      const Symbol_table*,
      const Stringpool*,
      unsigned int,
      const std::vector<Symbol*>&,
      unsigned char**,
      unsigned int*) const;
  #endif
  
  #ifdef HAVE_TARGET_64_LITTLE
  template
  void
  Versions::symbol_section_contents<64, false>(
      const Symbol_table*,
      const Stringpool*,
      unsigned int,
      const std::vector<Symbol*>&,
      unsigned char**,
      unsigned int*) const;
  #endif
  
  #ifdef HAVE_TARGET_64_BIG
  template
  void
  Versions::symbol_section_contents<64, true>(
      const Symbol_table*,
      const Stringpool*,
      unsigned int,
      const std::vector<Symbol*>&,
      unsigned char**,
      unsigned int*) const;
  #endif
  
  #ifdef HAVE_TARGET_32_LITTLE
  template
  void
  Versions::def_section_contents<32, false>(
      const Stringpool*,
      unsigned char**,
      unsigned int*,
      unsigned int*) const;
  #endif
  
  #ifdef HAVE_TARGET_32_BIG
  template
  void
  Versions::def_section_contents<32, true>(
      const Stringpool*,
      unsigned char**,
      unsigned int*,
      unsigned int*) const;
  #endif
  
  #ifdef HAVE_TARGET_64_LITTLE
  template
  void
  Versions::def_section_contents<64, false>(
      const Stringpool*,
      unsigned char**,
      unsigned int*,
      unsigned int*) const;
  #endif
  
  #ifdef HAVE_TARGET_64_BIG
  template
  void
  Versions::def_section_contents<64, true>(
      const Stringpool*,
      unsigned char**,
      unsigned int*,
      unsigned int*) const;
  #endif
  
  #ifdef HAVE_TARGET_32_LITTLE
  template
  void
  Versions::need_section_contents<32, false>(
      const Stringpool*,
      unsigned char**,
      unsigned int*,
      unsigned int*) const;
  #endif
  
  #ifdef HAVE_TARGET_32_BIG
  template
  void
  Versions::need_section_contents<32, true>(
      const Stringpool*,
      unsigned char**,
      unsigned int*,
      unsigned int*) const;
  #endif
  
  #ifdef HAVE_TARGET_64_LITTLE
  template
  void
  Versions::need_section_contents<64, false>(
      const Stringpool*,
      unsigned char**,
      unsigned int*,
      unsigned int*) const;
  #endif
  
  #ifdef HAVE_TARGET_64_BIG
  template
  void
  Versions::need_section_contents<64, true>(
      const Stringpool*,
      unsigned char**,
      unsigned int*,
      unsigned int*) const;
  #endif
  
  } // End namespace gold.
  