Add elf header parsing
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Quentin Legot
parent
703c8e5448
commit
b4b7eb69c2
@ -1,40 +1,11 @@
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use crate::Machine;
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use std::f32::consts::E;
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use std::fs;
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use std::io;
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use std::io::BufRead;
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use std::io::Read;
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/// Load a file into a new machine
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///
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/// `panic!` when size is not 1, 2, 4 or 8
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/// `panic!` when the text does not represents instructions in hexadecimal
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///
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/// ### Parameters
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///
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/// - **path** the path of the file to load
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/// - **size** the number of bytes to write (1, 2, 4 or 8)
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#[deprecated]
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pub fn _load(path : &str, instruction_size: i32) -> Machine {
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let file = fs::File::open(path).expect("Wrong filename");
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let reader = io::BufReader::new(file);
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let mut machine = Machine::init_machine();
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for (i,line) in reader.lines().enumerate() {
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let res = u64::from_str_radix(&line.unwrap(), 16);
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match res {
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Ok(value) => {
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Machine::write_memory(&mut machine, instruction_size, i*instruction_size as usize, value);
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},
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_ => panic!()
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}
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}
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println!("{:x}", Machine::read_memory(& mut machine, 4, 0));
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machine
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}
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/// load a 32-bits binary file into the machine
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///
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/// ### Parameters
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@ -63,3 +34,170 @@ pub fn load(path: &str, machine: &mut Machine, start_index: usize) -> Result<(),
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// println!("{:04x?}", instructions); // only print loaded program in debug build
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Ok(())
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}
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struct Loader {
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bytes: Vec<u8>
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}
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impl Loader {
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pub fn load(path: &str, machine: &mut Machine, start_index: usize) -> Result<Self, std::io::Error> {
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let mut file = fs::File::open(path)?;
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let mut instructions: Vec<u8> = Default::default();
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loop {
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let mut buf: [u8; 1] = [0; 1];
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let res = file.read(&mut buf)?;
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if res == 0 {
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break; // eof
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} else {
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instructions.push(buf[0]);
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}
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}
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// #[cfg(debug_assertions)]
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// println!("{:04x?}", instructions); // only print loaded program in debug build
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Ok(Self { bytes: instructions })
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}
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fn parse(&mut self) -> Result<(), ()> {
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todo!();
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Ok(())
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}
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/// return true if the 4 first bytes constitude the elf magic number
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fn is_elf(&self) -> bool {
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self.bytes.get(0..4) == Option::Some(&[0x7f, 0x45, 0x4c, 0x46])
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}
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/// return true if big endian, false otherwise
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fn check_endianess(&self) -> bool {
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self.bytes.get(5) == Option::Some(&2)
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}
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/// return true if file is 32 bits, false if 64 bits
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fn is_32bits(&self) -> bool {
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self.bytes.get(4) == Option::Some(&1)
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}
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/// return the version of the elf file (should be 1)
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/// Can be None if the file is smaller than 7 bytes -> the file is invalid
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fn get_version(&self) -> Option<u8> {
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self.bytes.get(6).copied() // work as primitives implements Copy
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}
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/// return true if target abi of the binary file is System V, false otherwise
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fn is_system_v_elf(&self) -> bool{
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self.bytes.get(7) == Option::Some(&0)
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}
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/// return true if specified target instruction set architecture is RISCV
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fn is_riscv_isa(&self) -> bool {
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self.bytes.get(0x12) == Option::Some(&0xf7)
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}
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/// memory address of the entry point from where the process starts its execution
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fn get_entrypoint(&self, is_32bits: bool) -> Option<u64> {
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if is_32bits {
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self.get_address_point(0x18, true)
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} else {
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self.get_address_point(0x18, false)
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}
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}
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/// Memory address of the start of the program header table
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fn get_program_header_table_location(&self, is_32bits: bool) -> Option<u64> {
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if is_32bits {
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self.get_address_point(0x1c, true)
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} else {
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self.get_address_point(0x20, false)
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}
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}
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/// Memory address of the start of the section header table
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fn get_section_header_table_location(&self, is_32bits: bool) -> Option<u64> {
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if is_32bits {
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self.get_address_point(0x20, true)
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} else {
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self.get_address_point(0x28, false)
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}
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}
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/// Return the size of the header, normally, 0x40 for 64 bits bin and 0x34 for 32 bits
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fn get_elf_header_size(&self, is_32bits: bool) -> Option<u16> {
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let address = if is_32bits { 0x28 } else { 0x34 };
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self.get_u16_value(address)
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}
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/// return the size of the program header
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fn get_program_header_size(&self, is_32bits: bool) -> Option<u16> {
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let address = if is_32bits { 0x2a } else { 0x34 };
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self.get_u16_value(address)
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}
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/// return the number of entries in the program header
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fn get_number_entries_program_header(&self, is_32bits: bool) -> Option<u16> {
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let address = if is_32bits { 0x2c } else { 0x38 };
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self.get_u16_value(address)
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}
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/// Return the size of the section header
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fn get_section_header_size(&self, is_32bits: bool) -> Option<u16> {
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let address = if is_32bits { 0x2e } else { 0x3a };
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self.get_u16_value(address)
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}
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/// Return the number of entries in the section header
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fn get_section_header_num_entries(&self, is_32bits: bool) -> Option<u16> {
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let address = if is_32bits { 0x30 } else { 0x3c };
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self.get_u16_value(address)
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}
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/// Return a u16 value, usually for the size or the number of entries inside a header
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fn get_u16_value(&self, address: usize) -> Option<u16> {
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let mut bytes: [u8; 2] = [0; 2];
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bytes[0] = self.bytes.get(address).copied()?;
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bytes[1] = self.bytes.get(address + 1).copied()?;
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Option::Some(u16::from_le_bytes(bytes))
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}
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/// return the memory address of something stored at address
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/// Can return None if the file is smaller than adress + 4 (or 7 if 64 bits), in this case, the elf header is incorrect
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fn get_address_point(&self, address: usize, is_32bits: bool) -> Option<u64> {
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if is_32bits {
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let mut bytes: [u8; 4] = [0; 4];
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bytes[0] = self.bytes.get(address).copied()?;
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bytes[0] = self.bytes.get(address + 1).copied()?;
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bytes[0] = self.bytes.get(address + 2).copied()?;
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bytes[0] = self.bytes.get(address + 3).copied()?;
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Option::Some(u32::from_le_bytes(bytes) as u64)
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} else {
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let mut bytes: [u8; 8] = [0; 8];
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bytes[0] = self.bytes.get(address).copied()?;
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bytes[0] = self.bytes.get(address + 1).copied()?;
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bytes[0] = self.bytes.get(address + 2).copied()?;
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bytes[0] = self.bytes.get(address + 3).copied()?;
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bytes[0] = self.bytes.get(address + 4).copied()?;
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bytes[0] = self.bytes.get(address + 5).copied()?;
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bytes[0] = self.bytes.get(address + 6).copied()?;
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bytes[0] = self.bytes.get(address + 7).copied()?;
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Option::Some(u64::from_le_bytes(bytes))
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}
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}
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}
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#[cfg(test)]
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mod test {
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use crate::simulator::{loader::Loader, machine::Machine};
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#[test]
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fn test_parse() {
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let mut machine = Machine::init_machine();
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let loader = Loader::load("./test/riscv_instructions/simple_arithmetics/unsigned_addition", &mut machine, 0).expect("IO Error");
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assert_eq!(true, loader.is_elf());
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assert_eq!(false, loader.is_32bits());
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assert_eq!(false, loader.check_endianess());
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}
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}
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