// -*- mode: C++; indent-tabs-mode: nil; c-basic-offset: 4 -*-

/*
 * (c) 2016 Vladimír Štill <xstill@fi.muni.cz>
 */

/* Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright notice,
 *    this list of conditions and the following disclaimer.
 *
 * 2. Redistributions in binary form must reproduce the above copyright notice,
 *    this list of conditions and the following disclaimer in the documentation
 *    and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE. */

#ifdef DIVINE_RELAX_WARNINGS
DIVINE_RELAX_WARNINGS
#endif

#include <llvm/Support/ELF.h>

#ifdef DIVINE_RELAX_WARNINGS
DIVINE_UNRELAX_WARNINGS
#endif

#include <brick-assert>
#include <brick-mmap>
#include <memory>
#include <string>

namespace brick {
namespace elf {

struct Section {

    using iterator = char *;

    Section() : _data( nullptr ), _size( 0 ) { }
    Section( const char *data, size_t size ) : _data( data ), _size( size ) { }

    const char *data() const { return _data; }
    size_t size() const { return _size; }

    const char *begin() const { return _data; }
    const char *end() const { return _data + _size; }

    explicit operator bool() const { return _data; }
    explicit operator std::string() const { return std::string( begin(), end() ); }

  private:
    const char *_data;
    size_t _size;
};

struct ElfObject {

    using Ehdr = ::llvm::ELF::Elf64_Ehdr;
    using Shdr = ::llvm::ELF::Elf64_Shdr;

    explicit ElfObject( std::string path, bool validate = true ) :
        _mmap( path ),
        _ehdr( &_mmap.template get< ::llvm::ELF::Elf64_Ehdr >( 0 ) )
    {
        if ( validate )
            _validate();
    }

    explicit ElfObject( const char *data, bool validate = true ) :
        _ehdr( reinterpret_cast< const ::llvm::ELF::Elf64_Ehdr * >( data ) )
    {
        if ( validate )
            _validate();
    }

    bool valid() const {
        return _ehdr
            && _ehdr->checkMagic()
            && _ehdr->getFileClass() == ::llvm::ELF::ELFCLASS64
            && _ehdr->getDataEncoding() == ::llvm::ELF::ELFDATA2LSB;
    }

    const Shdr &sectionHeader( int i ) const {
        ASSERT_LEQ( 0, i );
        ASSERT_LT( i, sectionsCount() );
        return *reinterpret_cast< const Shdr * >( raw() + _ehdr->e_shoff + i * _ehdr->e_shentsize );
    }

    const char *sectionStart( int i ) const { return sectionStart( sectionHeader( i ) ); }
    const char *sectionStart( const Shdr &hdr ) const {
        return raw() + hdr.sh_offset;
    }

    size_t sectionSize( int i ) const { return sectionSize( sectionHeader( i ) ); }
    size_t sectionSize( const Shdr &hdr ) const { return hdr.sh_size; }

    Section section( int i ) const { return section( sectionHeader( i ) ); }
    Section section( const Shdr &hdr ) const {
        return Section( sectionStart( hdr ), sectionSize( hdr ) );
    }

    std::vector< Section > sectionsByName( std::string name ) {
        std::vector< Section > out;
        for ( int i = 0, end = sectionsCount(); i != end; ++i ) {
            if ( sectionName( i ) == name )
                out.emplace_back( section( i ) );
        }
        return out;
    }

    const Shdr &sectionNamesSection() const {
        return sectionHeader( _ehdr->e_shstrndx );
    }

    const char *sectionNames() const {
        return sectionStart( sectionNamesSection() );
    }

    int sectionsCount() const { return _ehdr->e_shnum; }

    std::string sectionName( int i ) const {
        auto idx = sectionHeader( i ).sh_name;
        return sectionNames() + idx;
    }

  private:
    const char *raw() const { return reinterpret_cast< const char * >( _ehdr ); }

    void _validate() {
        ASSERT( _ehdr->checkMagic() );
        ASSERT( _ehdr->getFileClass() == ::llvm::ELF::ELFCLASS64 );
        ASSERT( _ehdr->getDataEncoding() == ::llvm::ELF::ELFDATA2LSB );
    }

    brick::mmap::MMap _mmap;
    const Ehdr *_ehdr;
};

}
}

// vim: syntax=cpp tabstop=4 shiftwidth=4 expandtab ft=cpp