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// dynobj.cc -- dynamic object support for gold

// 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.

#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 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_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;

    }

}

// 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;

  if (this->dynsym_shndx_ != -1U)

    {

      // Get the dynamic symbols.

      typename This::Shdr dynsymshdr(pshdrs

                                     + this->dynsym_shndx_ * This::shdr_size);

      gold_assert(dynsymshdr.get_sh_type() == elfcpp::SHT_DYNSYM);

      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>