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use elf_utilities::{
file::ELF64,
};
use std::io::{BufWriter, Write};
use std::os::unix::fs::OpenOptionsExt;
use crate::assembler::resources::{RelaSymbol, Symbol};
use indexmap::map::IndexMap;
pub struct ELFBuilder {
output_filepath: String,
file: ELF64,
}
impl ELFBuilder {
pub fn new(file_path: String) -> Self {
Self {
output_filepath: file_path,
file: ELF64::new(Self::initialize_elf64_header()),
}
}
pub fn generate_elf_file(&self, mode: u32) {
let bytes = self.file.to_le_bytes();
let file = std::fs::OpenOptions::new()
.create(true)
.read(true)
.write(true)
.mode(mode)
.open(&self.output_filepath)
.unwrap();
let mut writer = BufWriter::new(file);
match writer.write_all(&bytes) {
Ok(_) => (),
Err(e) => eprintln!("{}", e),
}
match writer.flush() {
Ok(_) => (),
Err(e) => eprintln!("{}", e),
}
}
pub fn add_section(&mut self, section: elf_utilities::section::Section64) {
self.file.add_section(section);
}
pub fn add_text_section(&mut self, symbols: &IndexMap<String, Symbol>) {
let mut all_symbol_codes: Vec<u8> = Vec::new();
for (_name, sym) in symbols.iter() {
let mut symbol_codes = sym.codes.clone();
all_symbol_codes.append(&mut symbol_codes);
}
let text_shdr =
self.init_text_section_header(all_symbol_codes.len());
let mut text_section =
elf_utilities::section::Section64::new(".text".to_string(), text_shdr);
text_section.bytes = Some(all_symbol_codes);
self.add_section(text_section);
}
pub fn add_symbol_table_section(&mut self, symbols: &IndexMap<String, Symbol>) {
let mut elf_symbols = vec![
elf_utilities::symbol::Symbol64::new_null_symbol(),
self.create_section_symbol(1),
];
let mut symbol_name_index: elf_utilities::Elf64Word = 1;
let mut symbol_offset: elf_utilities::Elf64Addr = 0;
for (symbol_name, symbol_info) in symbols.iter() {
let symbol_code_length = symbol_info.codes.len();
let symbol_name_length = symbol_name.len();
let mut global_symbol = self.create_global_symbol(
symbol_name_index,
symbol_code_length as u64,
symbol_offset,
);
global_symbol.set_symbol_name(symbol_name.to_string());
elf_symbols.push(global_symbol);
symbol_name_index += symbol_name_length as elf_utilities::Elf64Word + 1;
symbol_offset += symbol_code_length as elf_utilities::Elf64Addr;
}
let symbol_table_size = elf_symbols.len() * elf_utilities::symbol::Symbol64::size() as usize;
let symtab_section_header =
self.init_symbol_table_section_header(symbol_table_size as u64);
let mut symtab_section =
elf_utilities::section::Section64::new(".symtab".to_string(), symtab_section_header);
symtab_section.symbols = Some(elf_symbols);
self.add_section(symtab_section);
}
pub fn add_symtab_string_section(&mut self, symbols: &IndexMap<String, Symbol>) {
let symbol_names: Vec<&str> = symbols
.iter()
.map(|(name, _)| name.as_str())
.collect::<Vec<&str>>();
let symbol_string_table = elf_utilities::section::build_string_table(symbol_names);
let strtab_header =
self.init_string_table_header(symbol_string_table.len() as elf_utilities::Elf64Xword);
let mut strtab_section =
elf_utilities::section::Section64::new(".strtab".to_string(), strtab_header);
strtab_section.bytes = Some(symbol_string_table);
self.add_section(strtab_section);
}
pub fn add_relatext_section(&mut self, reloc_syms: &IndexMap<String, Vec<RelaSymbol>>) {
let mut relas = Vec::new();
for (_rela_name, relocs_in_syms) in reloc_syms.iter() {
for rela in relocs_in_syms.iter() {
relas.push(rela.rela64);
}
}
let mut rela_table_binary: Vec<u8> = Vec::new();
for rela in relas.iter() {
let mut rela_entry_binary = rela.to_le_bytes();
rela_table_binary.append(&mut rela_entry_binary);
}
let relatext_hdr = self.init_relatext_header(rela_table_binary.len() as u64);
let mut relatext_section =
elf_utilities::section::Section64::new(".rela.text".to_string(), relatext_hdr);
relatext_section.rela_symbols = Some(relas);
self.add_section(relatext_section);
}
pub fn add_nodata_section(&mut self) {
let nodata_header = self.init_nodata_header();
let mut nodata_section =
elf_utilities::section::Section64::new(".nodata".to_string(), nodata_header);
nodata_section.bytes = Some(Vec::new());
self.add_section(nodata_section);
}
pub fn add_shstrtab_string_section(&mut self) {
let section_names = vec![
".text",
".symtab",
".strtab",
".rela.text",
".nodata",
".shstrtab",
];
let section_string_table = elf_utilities::section::build_string_table(section_names);
let shstrtab_header =
self.init_string_table_header(section_string_table.len() as elf_utilities::Elf64Xword);
let mut shstrtab_section =
elf_utilities::section::Section64::new(".shstrtab".to_string(), shstrtab_header);
shstrtab_section.bytes = Some(section_string_table);
self.add_section(shstrtab_section);
}
pub fn condition_elf_header(&mut self) {
self.file.condition();
}
fn init_text_section_header(
&self,
length: usize,
) -> elf_utilities::section::Shdr64 {
let mut shdr: elf_utilities::section::Shdr64 = Default::default();
shdr.set_type(elf_utilities::section::TYPE::PROGBITS);
shdr.set_size(length as elf_utilities::Elf64Xword);
shdr.set_addralign(1);
shdr.set_flags(elf_utilities::section::SHF_ALLOC | elf_utilities::section::SHF_EXECINSTR);
shdr
}
fn init_symbol_table_section_header(
&self,
length: elf_utilities::Elf64Xword,
) -> elf_utilities::section::Shdr64 {
let mut shdr: elf_utilities::section::Shdr64 = Default::default();
shdr.set_type(elf_utilities::section::TYPE::SYMTAB);
shdr.set_size(length);
shdr.set_addralign(1);
shdr.set_entry_size(elf_utilities::symbol::Symbol64::size());
shdr.set_link(3);
shdr.set_info(2);
shdr
}
fn init_string_table_header(
&self,
length: elf_utilities::Elf64Xword,
) -> elf_utilities::section::Shdr64 {
let mut shdr: elf_utilities::section::Shdr64 = Default::default();
shdr.set_type(elf_utilities::section::TYPE::STRTAB);
shdr.set_size(length);
shdr.set_addralign(1);
shdr
}
fn init_relatext_header(
&self,
length: elf_utilities::Elf64Xword,
) -> elf_utilities::section::Shdr64 {
let mut shdr: elf_utilities::section::Shdr64 = Default::default();
shdr.set_type(elf_utilities::section::TYPE::RELA);
shdr.set_size(length);
shdr.set_flags(elf_utilities::section::section_flag::SHF_INFO_LINK);
shdr.set_addralign(8);
shdr.set_entry_size(elf_utilities::relocation::Rela64::size());
shdr.set_link(2);
shdr.set_info(1);
shdr
}
fn init_nodata_header(&self) -> elf_utilities::section::Shdr64 {
let mut shdr: elf_utilities::section::Shdr64 = Default::default();
shdr.set_type(elf_utilities::section::TYPE::NULL);
shdr
}
fn create_global_symbol(
&self,
st_name: elf_utilities::Elf64Word,
st_size: elf_utilities::Elf64Xword,
st_offset: elf_utilities::Elf64Addr,
) -> elf_utilities::symbol::Symbol64 {
let mut symbol: elf_utilities::symbol::Symbol64 = Default::default();
symbol.set_name(st_name);
symbol.set_size(st_size);
symbol.set_value(st_offset);
symbol.set_shndx(1);
let sym_info = elf_utilities::symbol::symbol_info(
elf_utilities::symbol::STB_GLOBAL,
elf_utilities::symbol::STT_FUNC,
);
symbol.set_info(sym_info);
symbol
}
fn create_section_symbol(&self, shndx: u16) -> elf_utilities::symbol::Symbol64 {
let mut symbol: elf_utilities::symbol::Symbol64 = Default::default();
symbol.set_shndx(shndx);
let sym_info = elf_utilities::symbol::symbol_info(
elf_utilities::symbol::STB_LOCAL,
elf_utilities::symbol::STT_SECTION,
);
symbol.set_info(sym_info);
symbol
}
fn initialize_elf64_header() -> elf_utilities::header::Ehdr64 {
let mut ehdr: elf_utilities::header::Ehdr64 = Default::default();
ehdr.set_machine(elf_utilities::header::ELFMACHINE::EMX8664);
ehdr.set_class(elf_utilities::header::ELFCLASS::CLASS64);
ehdr.set_elf_type(elf_utilities::header::ELFTYPE::REL);
ehdr.set_data(elf_utilities::header::ELFDATA::DATA2LSB);
ehdr.set_version(elf_utilities::header::ELFVERSION::VERSIONCURRENT);
ehdr
}
}