/*
Copyright (C) 2001-present by Serge Lamikhov-Center

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

#ifndef ELFIO_VERSYM_HPP
#define ELFIO_VERSYM_HPP

namespace ELFIO {

//------------------------------------------------------------------------------
template <class S> class versym_section_accessor_template
{
  public:
    //------------------------------------------------------------------------------
    explicit versym_section_accessor_template( S* section )
        : versym_section( section )
    {
        if ( section != nullptr ) {
            entries_num = decltype( entries_num )( section->get_size() /
                                                   sizeof( Elf_Half ) );
        }
    }

    //------------------------------------------------------------------------------
    Elf_Word get_entries_num() const
    {
        if ( versym_section ) {
            return entries_num;
        }
        return 0;
    }

    //------------------------------------------------------------------------------
    bool get_entry( Elf_Word no, Elf_Half& value ) const
    {
        if ( versym_section && ( no < get_entries_num() ) ) {
            value = ( (Elf_Half*)versym_section->get_data() )[no];
            return true;
        }

        return false;
    }

    //------------------------------------------------------------------------------
    bool modify_entry( Elf_Word no, Elf_Half value )
    {
        if ( versym_section && ( no < get_entries_num() ) ) {
            ( (Elf_Half*)versym_section->get_data() )[no] = value;
            return true;
        }

        return false;
    }

    //------------------------------------------------------------------------------
    bool add_entry( Elf_Half value )
    {
        if ( !versym_section ) {
            return false;
        }

        versym_section->append_data( (const char*)&value, sizeof( Elf_Half ) );
        ++entries_num;

        return true;
    }

    //------------------------------------------------------------------------------
  private:
    S*       versym_section = nullptr;
    Elf_Word entries_num    = 0;
};

using versym_section_accessor = versym_section_accessor_template<section>;
using const_versym_section_accessor =
    versym_section_accessor_template<const section>;

//------------------------------------------------------------------------------
template <class S> class versym_r_section_accessor_template
{
  public:
    //------------------------------------------------------------------------------
    versym_r_section_accessor_template( const elfio& elf_file,
                                        S*           versym_r_section )
        : elf_file( elf_file ), versym_r_section( versym_r_section ),
          entries_num( 0 )
    {
        // Find .dynamic section
        const section* dynamic_section = elf_file.sections[".dynamic"];

        if ( dynamic_section == nullptr ) {
            return;
        }

        const_dynamic_section_accessor dynamic_section_acc( elf_file,
                                                            dynamic_section );
        Elf_Xword dyn_sec_num = dynamic_section_acc.get_entries_num();
        for ( Elf_Xword i = 0; i < dyn_sec_num; ++i ) {
            Elf_Xword   tag;
            Elf_Xword   value;
            std::string str;

            if ( dynamic_section_acc.get_entry( i, tag, value, str ) &&
                 tag == DT_VERNEEDNUM ) {
                entries_num = (Elf_Word)value;
                break;
            }
        }
    }

    //------------------------------------------------------------------------------
    Elf_Word get_entries_num() const { return entries_num; }

    //------------------------------------------------------------------------------
    bool get_entry( Elf_Word     no,
                    Elf_Half&    version,
                    std::string& file_name,
                    Elf_Word&    hash,
                    Elf_Half&    flags,
                    Elf_Half&    other,
                    std::string& dep_name ) const
    {
        if ( versym_r_section == nullptr || ( no >= get_entries_num() ) ) {
            return false;
        }

        const_string_section_accessor string_section_acc(
            elf_file.sections[versym_r_section->get_link()] );

        Elfxx_Verneed* verneed = (Elfxx_Verneed*)versym_r_section->get_data();
        Elfxx_Vernaux* veraux =
            (Elfxx_Vernaux*)( (char*)verneed + verneed->vn_aux );
        for ( Elf_Word i = 0; i < no; ++i ) {
            verneed = (Elfxx_Verneed*)( (char*)verneed + verneed->vn_next );
            veraux  = (Elfxx_Vernaux*)( (char*)verneed + verneed->vn_aux );
        }

        version   = verneed->vn_version;
        file_name = string_section_acc.get_string( verneed->vn_file );
        hash      = veraux->vna_hash;
        flags     = veraux->vna_flags;
        other     = veraux->vna_other;
        dep_name  = string_section_acc.get_string( veraux->vna_name );

        return true;
    }

    //------------------------------------------------------------------------------
  private:
    const elfio& elf_file;
    S*           versym_r_section = nullptr;
    Elf_Word     entries_num      = 0;
};

using versym_r_section_accessor = versym_r_section_accessor_template<section>;
using const_versym_r_section_accessor =
    versym_r_section_accessor_template<const section>;

//------------------------------------------------------------------------------
template <class S> class versym_d_section_accessor_template
{
  public:
    //------------------------------------------------------------------------------
    versym_d_section_accessor_template( const elfio& elf_file,
                                        S*           versym_d_section )
        : elf_file( elf_file ), versym_d_section( versym_d_section ),
          entries_num( 0 )
    {
        // Find .dynamic section
        const section* dynamic_section = elf_file.sections[".dynamic"];

        if ( dynamic_section == nullptr ) {
            return;
        }

        const_dynamic_section_accessor dynamic_section_acc( elf_file,
                                                            dynamic_section );
        Elf_Xword dyn_sec_num = dynamic_section_acc.get_entries_num();
        for ( Elf_Xword i = 0; i < dyn_sec_num; ++i ) {
            Elf_Xword   tag;
            Elf_Xword   value;
            std::string str;

            if ( dynamic_section_acc.get_entry( i, tag, value, str ) &&
                 tag == DT_VERDEFNUM ) {
                entries_num = (Elf_Word)value;
                break;
            }
        }
    }

    //------------------------------------------------------------------------------
    Elf_Word get_entries_num() const { return entries_num; }

    //------------------------------------------------------------------------------
    bool get_entry( Elf_Word     no,
                    Elf_Half&    flags,
                    Elf_Half&    version_index,
                    Elf_Word&    hash,
                    std::string& dep_name ) const
    {
        if ( versym_d_section == nullptr || ( no >= get_entries_num() ) ) {
            return false;
        }

        const_string_section_accessor string_section_acc(
            elf_file.sections[versym_d_section->get_link()] );

        Elfxx_Verdef*  verdef = (Elfxx_Verdef*)versym_d_section->get_data();
        Elfxx_Verdaux* verdaux =
            (Elfxx_Verdaux*)( (char*)verdef + verdef->vd_aux );
        for ( Elf_Word i = 0; i < no; ++i ) {
            verdef  = (Elfxx_Verdef*)( (char*)verdef + verdef->vd_next );
            verdaux = (Elfxx_Verdaux*)( (char*)verdef + verdef->vd_aux );
        }

        // verdef->vd_version should always be 1
        // see https://refspecs.linuxfoundation.org/LSB_3.0.0/LSB-PDA/LSB-PDA.junk/symversion.html#VERDEFENTRIES
        // verdef->vd_cnt should always be 1.
        // see https://maskray.me/blog/2020-11-26-all-about-symbol-versioning

        flags         = verdef->vd_flags;
        version_index = verdef->vd_ndx;
        hash          = verdef->vd_hash;
        dep_name      = string_section_acc.get_string( verdaux->vda_name );

        return true;
    }

    //------------------------------------------------------------------------------
  private:
    const elfio& elf_file;
    S*           versym_d_section = nullptr;
    Elf_Word     entries_num      = 0;
};

using versym_d_section_accessor = versym_d_section_accessor_template<section>;
using const_versym_d_section_accessor =
    versym_d_section_accessor_template<const section>;

} // namespace ELFIO

#endif // ELFIO_VERSYM_HPP