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converter.h
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converter.h
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#ifndef ZAD1_ELF_CONVERTER_CONVERTER_H
#define ZAD1_ELF_CONVERTER_CONVERTER_H
#include <elf.h>
#include <fstream>
#include <memory>
#include <utility>
#include <vector>
#include <set>
#include <deque>
#include <optional>
#include <map>
#define read_to_field(ifstream, field) ifstream.read(reinterpret_cast<char*>(&(field)), sizeof(field))
#define write_from_field(elf_stream, field) elf_stream.write(reinterpret_cast<char const*>(&(field)), sizeof(field))
namespace converter {
struct UnsupportedFileContent : public std::invalid_argument {
explicit UnsupportedFileContent(std::string const& what) : std::invalid_argument(what) {}
};
namespace func_spec {
enum struct ArgType {
int_t,
uint_t,
long_t,
ulong_t,
longlong_t,
ulonglong_t,
ptr_t,
};
struct Arg {
ArgType type;
static ArgType parse_arg_type(char const* argtype);
Arg(const std::string& argtype) : type{parse_arg_type(argtype.c_str())} {} // NOLINT(google-explicit-constructor)
[[nodiscard]] bool is_signed() const {
return type == ArgType::int_t || type == ArgType::long_t || type == ArgType::longlong_t;
}
[[nodiscard]] size_t bytes_32() const;
[[nodiscard]] size_t bytes_64() const;
[[nodiscard]] bool size_differs() const;
};
struct Ret {
std::optional<ArgType> const ret;
static std::optional<ArgType> parse_ret_type(char const* argtype);
explicit Ret(char const* argtype) : ret{parse_ret_type(argtype)} {}
};
struct Function {
std::string const name;
Ret const ret;
std::vector<Arg> const args;
explicit Function(std::string name, Ret ret, std::vector<Arg> args) : name{std::move(name)}, ret{std::move(ret)}, args{std::move(args)} {}
static Function from_line_decl(std::string const& decl);
struct order {
using is_transparent = void;
bool operator()(Function const& x, Function const& y) const {
return x.name < y.name;
}
bool operator()(std::string const& x, Function const& y) const {
return x < y.name;
}
bool operator()(Function const& x, std::string const& y) const {
return x.name < y;
}
};
};
struct Functions {
std::set<Function, Function::order> functions;
explicit Functions(std::ifstream& func_stream);
[[nodiscard]] decltype(functions.find("")) find(std::string const& name) const {
return functions.find(name);
}
[[nodiscard]] decltype(functions.end()) end() const {
return functions.end();
}
};
}
namespace stubs {
struct ThunkPreRel32 {
bool local_symbol;
Elf32_Addr offset;
Elf32_Sword addend;
explicit ThunkPreRel32(Elf64_Rela const& rela64);
};
struct Stub {
std::vector<uint8_t> code;
std::vector<ThunkPreRel32> relocations;
Stub(Stub const&) = delete;
Stub(Stub&&) = default;
private:
explicit Stub(std::ifstream& stub_elf);
static Stub from_assembly(std::string const& assembly);
public:
static std::string asmin(func_spec::Function const& func_spec);
static std::string asmout(func_spec::Function const& func_spec);
static Stub stubin(func_spec::Function const& func_spec);
static Stub stubout(func_spec::Function const& func_spec);
};
}
namespace elf64 {
struct Elf64;
struct Header64;
struct Rela64;
struct Symbol64;
struct Section64;
struct Section64WithoutData;
struct Section64WithGenericData;
struct Section64Strtab;
struct Section64Symtab;
struct Section64Rela;
}
namespace elf32 {
struct Section32;
struct Section32WithoutData;
struct Section32WithFixedSizeData;
struct Section32Symtab;
struct Section32Strtab;
struct Section32Rel;
struct Section32Rela;
struct Section32Thunk;
struct Section32Thunkin;
struct Section32Thunkout;
// deque prevents iterator invalidation after pushing to the back
using sections32_t = std::deque<std::unique_ptr<Section32>>;
struct Header32 : Elf32_Ehdr {
explicit Header32(elf64::Header64 const& header64);
[[nodiscard]] static constexpr size_t size() {
return sizeof(Elf32_Ehdr);
}
void write_out(std::ofstream& ofstream, size_t& offset) const;
};
struct Rela32 : Elf32_Rela {
explicit Rela32(elf64::Rela64 const& rela64);
};
struct Rel32 : Elf32_Rel {
private:
explicit Rel32(Elf32_Addr offset, Elf32_Word type, Elf32_Word symbol_idx);
public:
explicit Rel32(Rela32 const& rela32, Section32Rela const& section32_rela, sections32_t& sections);
static Rel32 thunk_self_ref(Elf32_Addr offset, Elf32_Word self_symbol_idx);
static Rel32 func_ref(Elf32_Addr offset, Elf32_Word func_symbol_idx);
void write_out(std::ofstream& elf_file, size_t& i) const;
};
struct Symbol32 : Elf32_Sym {
private:
explicit Symbol32(Symbol32 const& symbol, Elf32_Word type, Elf32_Word binding,
Elf32_Word thunk_section_idx);
explicit Symbol32(Section32 const& section, Elf32_Word section_idx,
Elf32_Word section_name_idx);
public:
explicit Symbol32(elf64::Symbol64 const& symbol64);
static Symbol32 global_stub(Symbol32 const& local_symbol, Elf32_Word thunkin_section_idx);
static Symbol32 global_ref(Symbol32 const& global_symbol);
static Symbol32 for_section(Section32 const& section, Elf32_Word section_idx, Elf32_Word section_name_idx);
void write_out(std::ofstream& elf_file, size_t& i) const;
};
struct Thunk {
std::vector<uint8_t> code;
std::vector<Rel32> relocations;
explicit Thunk(stubs::Stub stub, size_t thunk_symbol_idx, size_t func_symbol_idx);
void lay_to_sections(Section32Thunk& thunk_section, Section32Rel& rel_thunk_section, Symbol32& thunk_symbol);
};
struct Thunkin final : public Thunk {
explicit Thunkin(func_spec::Function const& func_spec, size_t thunk_symbol_idx, size_t local_symbol_idx);
};
struct Thunkout final : public Thunk {
explicit Thunkout(func_spec::Function const& func_spec, size_t thunk_symbol_idx, size_t global_symbol_idx);
};
struct Section32 {
Elf32_Shdr header{};
explicit Section32(elf64::Section64 const §ion64);
explicit Section32(Elf32_Shdr const& header);
Section32(Section32&& section) = default;
virtual ~Section32() = default;
[[nodiscard]] virtual std::string to_string() const {
return "Section32 generic";
}
[[nodiscard]] char const* type() const;
static std::unique_ptr<Section32> convert_section(elf64::Section64 const& section64, Header32 const& elf_header);
virtual size_t size() = 0;
[[nodiscard]] size_t alignment() const {
return header.sh_addralign == 0 ? 1 : header.sh_addralign;
}
void set_offset(Elf32_Addr const offset) {
header.sh_offset = offset;
}
virtual void write_out_data(std::ofstream& elf_file, size_t& offset);
void write_out_header(std::ofstream& elf_file, size_t& offset) const;
void align_offset(size_t& offset) const;
void align_offset(size_t& offset, std::ofstream& elf_file) const;
};
struct Section32WithoutData : public Section32 {
Section32WithoutData(Section32WithoutData&& section) = default;
~Section32WithoutData() override = default;
explicit Section32WithoutData(elf64::Section64WithoutData const& section64);
size_t size() override;
[[nodiscard]] std::string to_string() const override {
return "Section32WithoutData";
}
};
struct Section32WithFixedSizeData : public Section32 {
std::unique_ptr<char[]> data;
~Section32WithFixedSizeData() override = default;
Section32WithFixedSizeData(Section32WithFixedSizeData&& section) = default;
explicit Section32WithFixedSizeData(elf64::Section64WithGenericData const& section64);
size_t size() override;
void write_out_data(std::ofstream& elf_file, size_t& offset) override;
[[nodiscard]] std::string to_string() const override {
return "Section32WithFixedSizeData";
}
};
struct Section32WithGrowableData : public Section32 {
std::vector<uint8_t> data;
~Section32WithGrowableData() override = default;
Section32WithGrowableData(Section32WithGrowableData&& section) = default;
explicit Section32WithGrowableData(Elf32_Shdr const& header);
explicit Section32WithGrowableData(elf64::Section64WithGenericData const& section64);
[[nodiscard]] size_t size() override;
void write_out_data(std::ofstream& elf_file, size_t& offset) override;
};
struct Section32Strtab final : public Section32WithGrowableData {
~Section32Strtab() override = default;
Section32Strtab(Section32Strtab&& section) = default;
explicit Section32Strtab(elf64::Section64Strtab const& strtab64);
[[nodiscard]] char const* name_of(Elf32_Word i) const {
return reinterpret_cast<char const*>(data.data() + i);
}
[[nodiscard]] Elf32_Word append_name(std::string const& name);
[[nodiscard]] std::string to_string() const override {
return "Section32Strtab";
}
};
struct Section32Symtab final : public Section32 {
std::deque<Symbol32> symbols;
~Section32Symtab() override = default;
Section32Symtab(Section32Symtab&& section) = default;
explicit Section32Symtab(elf64::Section64Symtab const& symtab);
[[nodiscard]] decltype(header.sh_link) strtab() const {
return header.sh_link;
}
Elf32_Word add_symbol(Symbol32 symbol);
Elf32_Word register_section(Section32 const& section, Elf32_Word section_idx, Elf32_Word section_name_idx);
[[nodiscard]] std::string to_string() const override {
return "Section32Symtab";
}
void write_out_data(std::ofstream& elf_file, size_t& offset) override;
size_t size() override;
};
struct Section32Rela final : public Section32 {
std::vector<Rela32> relocations;
~Section32Rela() override = default;
Section32Rela(Section32Rela&& section) = default;
explicit Section32Rela(elf64::Section64Rela const& rela64);
[[nodiscard]] std::string to_string() const override {
return "Section32Rela";
}
size_t size() override;
};
struct Section32Rel final : public Section32 {
std::vector<Rel32> relocations;
~Section32Rel() override = default;
Section32Rel(Section32Rel&& section) = default;
[[nodiscard]] std::string to_string() const override {
return "Section32Rel";
}
explicit Section32Rel(Section32Rela const& rela32, sections32_t& sections, Section32Strtab& shstrtab);
private:
explicit Section32Rel(Elf32_Shdr const& header) : Section32{header} {}
public:
static Section32Rel make_for_thunk(const Section32Thunk& thunk_section, Elf32_Word thunk_section_idx,
Section32Strtab& strtab, Elf32_Word symtab_idx);
void write_out_data(std::ofstream& elf_file, size_t& offset) override;
size_t size() override;
};
struct Section32Thunk : public Section32WithGrowableData {
~Section32Thunk() override = default;
Section32Thunk(Section32Thunk&& section) = default;
private:
explicit Section32Thunk(Elf32_Shdr const& header)
: Section32WithGrowableData{header} {}
public:
static Section32Thunk make_thunk(std::string const& thunk_section_name, size_t symtab_idx,
Section32Strtab& strtab, std::string const& name);
[[nodiscard]] size_t add_thunk(const std::vector<uint8_t>& stub);
};
struct Section32Thunkin final : public Section32Thunk {
~Section32Thunkin() override = default;
Section32Thunkin(Section32Thunkin&& section) = default;
explicit Section32Thunkin(std::string const& thunked_section_name, size_t const symtab_idx, Section32Strtab& strtab)
: Section32Thunk{make_thunk(thunked_section_name, symtab_idx, strtab, ".thunkin")} {}
};
struct Section32Thunkout final : public Section32Thunk {
~Section32Thunkout() override = default;
Section32Thunkout(Section32Thunkout&& section) = default;
explicit Section32Thunkout(std::string const& thunked_section_name, size_t const symtab_idx, Section32Strtab& strtab)
: Section32Thunk{make_thunk(thunked_section_name, symtab_idx, strtab, ".thunkout")} {}
};
struct Elf32 {
Header32 header;
sections32_t sections;
Section32Strtab*const shstrtab;
struct GlobalSymbolsStorage {
// (symbol_number -> symbol)
std::map<Elf32_Word, Symbol32> symbols;
// (section_number, relocation_number)
std::vector<std::pair<Elf32_Word, Elf32_Word>> relocations;
} storage;
explicit Elf32(elf64::Elf64 const& elf64, func_spec::Functions const& functions);
void add_new_section(std::unique_ptr<Section32> section);
void convert_relocations();
void store_and_move_global_symbols(func_spec::Functions const& functions);
void convert_symbols(func_spec::Functions const& functions);
void restore_global_symbols();
void correct_offsets();
void write_out(std::ofstream& elf_file) const;
};
}
namespace elf64 {
struct Header64 : Elf64_Ehdr {
explicit Header64(std::ifstream &elf_stream);
};
struct Symbol64 : Elf64_Sym {
explicit Symbol64(std::ifstream &elf_stream);
};
struct Rela64 : Elf64_Rela {
explicit Rela64(std::ifstream &elf_stream);
};
struct Section64 {
Elf64_Shdr header{};
explicit Section64(std::ifstream &elf_stream);
Section64(Section64&& section) = default;
virtual ~Section64() = default;
static std::unique_ptr<Section64> parse_section(std::ifstream& elf_stream, Elf64_Ehdr const& elf_header);
};
struct Section64WithoutData : public Section64 {
explicit Section64WithoutData(Section64 section64) : Section64(std::move(section64)) {}
~Section64WithoutData() override = default;
Section64WithoutData(Section64WithoutData&&) = default;
};
struct Section64WithGenericData : public Section64 {
std::unique_ptr<char[]> data;
explicit Section64WithGenericData(Section64 section64, std::ifstream& elf_stream);
~Section64WithGenericData() override = default;
Section64WithGenericData(Section64WithGenericData&&) = default;
};
struct Section64Strtab final : public Section64WithGenericData {
explicit Section64Strtab(Section64WithGenericData section64_with_data) : Section64WithGenericData(std::move(section64_with_data)) {}
~Section64Strtab() final = default;
Section64Strtab(Section64Strtab&&) = default;
[[nodiscard]] char const* name_of(Elf64_Word i) const {
return &data.get()[i];
}
};
struct Section64Rela final : public Section64 {
std::vector<Rela64> relocations;
explicit Section64Rela(Section64 section64, std::ifstream& elf_stream);
~Section64Rela() final = default;
Section64Rela(Section64Rela&&) = default;
};
struct Section64Symtab final : public Section64 {
std::vector<Symbol64> symbols;
explicit Section64Symtab(Section64 section64, std::ifstream& elf_stream);
~Section64Symtab() final = default;
Section64Symtab(Section64Symtab&&) = default;
};
struct Elf64 {
Header64 header;
std::vector<std::unique_ptr<Section64>> sections;
explicit Elf64(std::ifstream &elf_stream);
};
}
using elf64::Elf64;
using elf32::Elf32;
}
#endif //ZAD1_ELF_CONVERTER_CONVERTER_H