table_section.h

#ifndef TABLE_SECTION_H
#define TABLE_SECTION_H
 
#include "../common.h"
#include "reader.h"
#include "section.h"
#include "target.h"
#include "writer.h"
 
namespace Linker
{
    template <typename TableEntryType>
        class TableSection : public Section
    {
    public:
        ::EndianType endian_type = ::UndefinedEndian;
        std::vector<TableEntryType> entries;
 
        TableSection(::EndianType endian_type, std::string name, int flags = Readable)
            : Section(name, flags), endian_type(endian_type)
        {
            assert(!(flags & ZeroFilled));
        }
 
        TableSection(std::string name, int flags = Readable)
            : Section(name, flags)
        {
            assert(!(flags & ZeroFilled));
        }
 
        offset_t Size() const override
        {
            return entries.size() * TableEntryType::EntrySize + data.size();
        }
 
        offset_t SetZeroFilled(bool is_zero_filled) override
        {
            assert(!is_zero_filled);
            return 0;
        }
 
        void ReadFile(std::istream& in) override
        {
            for(auto& entry : entries)
            {
                TableEntryType::ReadFile(in, entry, endian_type);
            }
            Section::ReadFile(in);
        }
 
        void ReadFile(Reader& rd) override
        {
            for(auto& entry : entries)
            {
                TableEntryType::ReadFile(rd, entry, endian_type);
            }
            Section::ReadFile(rd);
        }
 
        template <typename OutputType>
            offset_t WriteTable(OutputType& out, offset_t bytes, offset_t offset) const
        {
            if(offset / TableEntryType::EntrySize >= entries.size())
                return 0;
 
            bytes = std::min(bytes, entries.size() * TableEntryType::EntrySize - offset);
 
            offset_t output_byte_count = 0;
            offset_t offset_in_entry = offset % TableEntryType::EntrySize;
            if(offset_in_entry != 0)
            {
                if(offset + bytes >= TableEntryType::EntrySize)
                {
                    // write first partial entry
                    TableEntryType::WriteFile(out, entries[offset / TableEntryType::EntrySize],
                        endian_type,
                        TableEntryType::EntrySize,
                        offset_in_entry);
                    output_byte_count += TableEntryType::EntrySize - offset_in_entry;
                    offset += TableEntryType::EntrySize - offset_in_entry;
                }
                else
                {
                    // write only partial entry
                    TableEntryType::WriteFile(out, entries[offset / TableEntryType::EntrySize],
                        endian_type,
                        bytes - offset_in_entry,
                        offset_in_entry);
                    output_byte_count += bytes;
                    offset += bytes;
                    bytes = 0;
                }
            }
 
            for(
                offset_t entry_index = offset / TableEntryType::EntrySize;
                entry_index < entries.size() && entry_index < (offset + bytes) / TableEntryType::EntrySize;
                entry_index++)
            {
                // write full entries
                TableEntryType::WriteFile(out, entries[entry_index], endian_type);
                output_byte_count += TableEntryType::EntrySize;
            }
 
            if(offset / TableEntryType::EntrySize < entries.size())
            {
                offset_t bytes_in_entry = bytes % TableEntryType::EntrySize;
                if(bytes_in_entry != 0)
                {
                    // write last partial entry
                    TableEntryType::WriteFile(out, entries[offset / TableEntryType::EntrySize],
                        endian_type,
                        bytes_in_entry,
                        offset);
                    output_byte_count += bytes;
                }
            }
 
            return output_byte_count;
        }
 
        using Section::WriteFile;
 
        offset_t WriteFile(std::ostream& out, offset_t bytes, offset_t offset = 0) const override
        {
            offset_t table_bytes = WriteTable(out, bytes, offset);
            return table_bytes + Section::WriteFile(out, bytes - table_bytes, offset + table_bytes);
        }
 
        offset_t WriteFile(Writer& wr, offset_t bytes, offset_t offset = 0) const override
        {
            offset_t table_bytes = WriteTable(wr, bytes, offset);
            return table_bytes + Buffer::WriteFile(wr, bytes - table_bytes, offset + table_bytes);
        }
 
        void Reset() override
        {
            Section::Reset();
            entries.clear();
        }
    };
 
    template <typename Int>
        struct Word
    {
    public:
        static constexpr offset_t EntrySize = sizeof(Int);
 
        static void ReadFile(std::istream& in, Word& word, ::EndianType endian_type)
        {
            Reader rd(endian_type, &in);
            ReadFile(rd, word);
        }
 
        static void ReadFile(Reader& rd, Word& word, ::EndianType endian_type = ::UndefinedEndian)
        {
            (void) endian_type; // ignored
            word.value = rd.ReadUnsigned(EntrySize); // TODO: ReadSigned for signed words
        }
 
        static void WriteFile(std::ostream& out, const Word& word, ::EndianType endian_type, offset_t bytes = EntrySize, offset_t offset = 0)
        {
            Writer wr(endian_type, &out);
            WriteFile(wr, word, endian_type, bytes, offset);
        }
 
        static void WriteFile(Writer& wr, const Word& word, ::EndianType endian_type = ::UndefinedEndian, offset_t bytes = EntrySize, offset_t offset = 0)
        {
            (void) endian_type; // ignored
            // TODO: not dealing with partial entries for now
            assert(bytes == EntrySize);
            assert(offset == 0);
            wr.WriteWord(EntrySize, word.value);
        }
 
        Int value;
    };
 
    // TODO: uint64_t
    class GOTEntry : public Word<uint32_t>
    {
    public:
        std::optional<Target> target;
 
        GOTEntry()
            : target()
        {
        }
 
        GOTEntry(Target target)
            : target(target)
        {
        }
 
        bool operator ==(const GOTEntry& other) const
        {
            return target == other.target;
        }
    };
 
    class GlobalOffsetTable : public TableSection<GOTEntry>
    {
    public:
        GlobalOffsetTable(::EndianType endian_type, std::string name, int flags = Readable)
            : TableSection<GOTEntry>(endian_type, name, flags)
        {
        }
 
        GlobalOffsetTable(std::string name, int flags = Readable)
            : TableSection<GOTEntry>(name, flags)
        {
        }
 
        void AddEntry(GOTEntry entry)
        {
            if(std::find(entries.begin(), entries.end(), entry) == entries.end())
            {
                entries.push_back(entry);
            }
        }
    };
}
 
#endif /* TABLE_SECTION_H */