text: // nacl.h -- Native Client support for gold    -*- C++ -*-
  
  // Copyright (C) 2012-2016 Free Software Foundation, Inc.
  
  // 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 "elfcpp_file.h"
  #include "fileread.h"
  #include "layout.h"
  #include "target-select.h"
  #include "target.h"
  
  #ifndef GOLD_NACL_H
  #define GOLD_NACL_H
  
  namespace gold
  {
  
  class Sniff_file
  {
   public:
    Sniff_file(Input_file* input_file, off_t offset)
      : file_(input_file->file()), offset_(offset)
    { }
  
    class Location
    {
     public:
      Location(off_t file_offset, off_t data_size)
        : offset_(file_offset), size_(data_size)
      { }
  
      inline off_t offset() const
      { return this->offset_; }
  
      inline section_size_type size() const
      { return this->size_; }
  
     private:
      off_t offset_;
      section_size_type size_;
    };
  
    class View
    {
     public:
      View(File_read& file, off_t file_offset, off_t data_size)
        : data_(file.get_view(file_offset, 0, data_size, true, false))
      { }
  
      const unsigned char* data()
      { return this->data_; }
  
     private:
      const unsigned char* data_;
    };
  
    View view(off_t file_offset, off_t data_size)
    {
      return View(this->file_, this->offset_ + file_offset, data_size);
    }
  
    View view(Location loc)
    {
      return this->view(loc.offset(), loc.size());
    }
  
    // Report an error.
    void
    error(const char* format, ...) const ATTRIBUTE_PRINTF_2;
  
   private:
    File_read& file_;
    off_t offset_;
  };
  
  
  template<class base_selector, class nacl_target>
  class Target_selector_nacl : public base_selector
  {
   public:
    Target_selector_nacl(const char* nacl_abi_name,
                         const char* bfd_name, const char* emulation)
      : base_selector(), is_nacl_(false), nacl_abi_name_(nacl_abi_name),
        bfd_name_(bfd_name), emulation_(emulation)
    { }
  
   protected:
    virtual Target*
    do_instantiate_target()
    {
      if (this->is_nacl_)
        return new nacl_target();
      return this->base_selector::do_instantiate_target();
    }
  
    virtual Target*
    do_recognize(Input_file* file, off_t offset,
                 int machine, int osabi, int abiversion)
    {
      this->is_nacl_ = file != NULL && this->recognize_nacl_file(file, offset);
      if (this->is_nacl_)
        return this->instantiate_target();
      return this->base_selector::do_recognize(file, offset,
                                               machine, osabi, abiversion);
    }
  
    virtual Target*
    do_recognize_by_bfd_name(const char* name)
    {
      gold_assert(this->bfd_name_ != NULL);
      this->is_nacl_ = strcmp(name, this->bfd_name_) == 0;
      if (this->is_nacl_)
        return this->instantiate_target();
      return this->base_selector::do_recognize_by_bfd_name(name);
    }
  
    virtual void
    do_supported_bfd_names(std::vector<const char*>* names)
    {
      gold_assert(this->bfd_name_ != NULL);
      this->base_selector::do_supported_bfd_names(names);
      names->push_back(this->bfd_name_);
    }
  
    virtual void
    do_supported_emulations(std::vector<const char*>* emulations)
    {
      gold_assert(this->emulation_ != NULL);
      this->base_selector::do_supported_emulations(emulations);
      emulations->push_back(this->emulation_);
    }
  
    virtual const char*
    do_target_bfd_name(const Target* target)
    {
      return (!this->is_our_target(target)
              ? NULL
              : (this->is_nacl_
                 ? this->bfd_name_
                 : base_selector::do_target_bfd_name(target)));
    }
  
   private:
    bool
    recognize_nacl_file(Input_file* input_file, off_t offset)
    {
      if (this->is_big_endian())
        {
  #if defined(HAVE_TARGET_32_BIG) || defined(HAVE_TARGET_64_BIG)
  # ifdef HAVE_TARGET_32_BIG
          if (this->get_size() == 32)
            return do_recognize_nacl_file<32, true>(input_file, offset);
  # endif
  # ifdef HAVE_TARGET_64_BIG
          if (this->get_size() == 64)
            return do_recognize_nacl_file<64, true>(input_file, offset);
  # endif
  #endif
          gold_unreachable();
        }
      else
        {
  #if defined(HAVE_TARGET_32_LITTLE) || defined(HAVE_TARGET_64_LITTLE)
  # ifdef HAVE_TARGET_32_LITTLE
          if (this->get_size() == 32)
            return do_recognize_nacl_file<32, false>(input_file, offset);
  # endif
  # ifdef HAVE_TARGET_64_LITTLE
          if (this->get_size() == 64)
            return do_recognize_nacl_file<64, false>(input_file, offset);
  # endif
  #endif
          gold_unreachable();
        }
    }
  
    template<int size, bool big_endian>
    bool
    do_recognize_nacl_file(Input_file* input_file, off_t offset)
    {
      Sniff_file file(input_file, offset);
      elfcpp::Elf_file<size, big_endian, Sniff_file> elf_file(&file);
      const unsigned int shnum = elf_file.shnum();
      for (unsigned int shndx = 1; shndx < shnum; ++shndx)
        {
          if (elf_file.section_type(shndx) == elfcpp::SHT_NOTE)
            {
              Sniff_file::Location loc = elf_file.section_contents(shndx);
              if (loc.size() < (3 * 4
                                + align_address(sizeof "NaCl", 4)
                                + align_address(nacl_abi_name_.size() + 1, 4)))
                continue;
              Sniff_file::View view(file.view(loc));
              const unsigned char* note_data = view.data();
              if ((elfcpp::Swap<32, big_endian>::readval(note_data + 0)
                   == sizeof "NaCl")
                  && (elfcpp::Swap<32, big_endian>::readval(note_data + 4)
                      == nacl_abi_name_.size() + 1)
                  && (elfcpp::Swap<32, big_endian>::readval(note_data + 8)
                      == elfcpp::NT_VERSION))
                {
                  const unsigned char* name = note_data + 12;
                  const unsigned char* desc = (name
                                               + align_address(sizeof "NaCl", 4));
                  if (memcmp(name, "NaCl", sizeof "NaCl") == 0
                      && memcmp(desc, nacl_abi_name_.c_str(),
                                nacl_abi_name_.size() + 1) == 0)
                    return true;
                }
            }
        }
      return false;
    }
  
    // Whether we decided this was the NaCl target variant.
    bool is_nacl_;
    // The string found in the NaCl ABI note.
    std::string nacl_abi_name_;
    // BFD name of NaCl target, for compatibility.
    const char* const bfd_name_;
    // GNU linker emulation for this NaCl target, for compatibility.
    const char* const emulation_;
  };
  
  } // end namespace gold
  
  #endif // !defined(GOLD_NACL_H)
  