304 lines
7.6 KiB
Rust
304 lines
7.6 KiB
Rust
use std::io::Read;
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use crate::state::{
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Block,
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Chunk,
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Instruction as Inst,
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};
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/// Invoke `luac` as a subprocess
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/// Luckily luac is single-pass, so we can just pipe in and out
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pub (crate) fn compile_bytecode (source: Vec <u8>) -> Vec <u8> {
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use std::{
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io::Write,
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process::{
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Command,
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Stdio,
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},
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};
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let mut child = Command::new ("luac")
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.arg ("-o") // Output to...
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.arg ("-") // Standard output
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.arg ("-") // Input from standard input
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.stdin (Stdio::piped ())
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.stdout (Stdio::piped ())
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.spawn ()
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.expect ("failed to execute `luac`. Is Lua installed?");
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let mut stdin = child.stdin.take ().expect ("failed to get stdin");
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std::thread::spawn (move || {
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stdin.write_all (&source).expect ("failed to write to stdin");
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});
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let output = child
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.wait_with_output ()
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.expect ("failed to wait on child");
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output.stdout.as_slice ().to_vec ()
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}
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pub fn parse_inst (buf: [u8; 4]) -> Option <Inst>
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{
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let opcode = buf [0] & 0x7f;
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let a = (buf [0] >> 7) | ((buf [1] & 0x7f) << 1);
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let b = buf [2];
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let c = buf [3];
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let bx =
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(((buf [1] >> 7) as u32) << 0) |
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((buf [2] as u32) << 1) |
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((buf [3] as u32) << 9);
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let bx = bx.try_into().ok ()?;
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let sbx = bx - 65535;
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let k = (buf [1] & 0x80) >> 7 == 1;
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let s_j = a as i32 + ((b as i32) << 8) + 1;
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Some (match opcode {
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0x00 => Inst::Move (a, b),
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0x01 => Inst::LoadI (a, sbx),
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0x02 => Inst::LoadF (a, sbx),
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0x03 => Inst::LoadK (a, bx),
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0x05 => Inst::LoadFalse (a),
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0x07 => Inst::LoadTrue (a),
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0x08 => Inst::LoadNil (a),
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0x09 => Inst::GetUpVal (a, b),
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0x0b => Inst::GetTabUp (a, b, c),
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0x0d => Inst::GetI (a, b, c),
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0x0f => Inst::SetTabUp (a, b, c),
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0x22 => Inst::Add (a, b, c),
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0x24 => Inst::Mul (a, b, c),
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0x2e => Inst::MmBin (a, b, c),
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0x33 => Inst::Not (a, b),
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0x3c => Inst::EqK (a, b, c),
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0x38 => Inst::Jmp (s_j),
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0x42 => Inst::Test (a, k),
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0x44 => Inst::Call (a, b, c),
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0x45 => Inst::TailCall (a, b, c, k),
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0x46 => Inst::Return (a, b, c, k),
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0x47 => Inst::Return0,
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0x48 => Inst::Return1 (a),
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0x4f => Inst::Closure (a, bx),
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0x51 => Inst::VarArgPrep (a.into ()),
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_ => return None,
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})
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}
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#[derive (Debug, PartialEq)]
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struct Header {
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inst_count: u8,
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}
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// loadString in PUC Lua. Doesn't work with long strings yet.
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fn parse_string <R: Read> (rdr: &mut R) -> Option <String> {
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let len = match parse_int (rdr)? {
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0 => 0,
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x => x - 1,
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};
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let mut buf = vec! [0u8; len as usize];
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rdr.read_exact (&mut buf).ok ()?;
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Some (String::from_utf8 (buf).ok ()?)
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}
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// loadByte in PUC Lua
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fn parse_byte <R: Read> (rdr: &mut R) -> Option <u8>
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{
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let mut buf = [0u8; 1];
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rdr.read_exact (&mut buf).ok ()?;
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Some (buf [0])
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}
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fn parse_int <R: Read> (rdr: &mut R) -> Option <u32>
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{
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Some ((parse_byte (rdr)? - 0x80) as u32)
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}
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// I'm doing this recursively so it's easy to match with the PUC Lua
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// code, but I don't like recursion in general, and I don't know
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// why PUC wrote it that way.
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pub fn parse_block <R: Read> (rdr: &mut R, blocks: &mut Vec <Block>)
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-> Option <()>
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{
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// Ignore things I haven't implemented yet
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parse_string (rdr)?; // function name
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parse_int (rdr)?; // start line in source code
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parse_int (rdr)?; // last line in source code
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parse_byte (rdr)?; // num params
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parse_byte (rdr)?; // is_vararg
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parse_byte (rdr)?; // maxstacksize, might be same as num slots?
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let inst_count = parse_int (rdr)?;
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let mut instructions = Vec::with_capacity (inst_count as usize);
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for _ in 0..inst_count {
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let mut buf = [0u8; 4];
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rdr.read_exact (&mut buf).ok ()?;
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instructions.push (parse_inst (buf).expect (&format! ("{buf:?}")));
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}
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let constant_count = parse_int (rdr)?;
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let mut constants = Vec::with_capacity (constant_count as usize);
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for _ in 0..constant_count {
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let const_type = parse_byte (rdr)?;
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assert_eq! (const_type, 0x04);
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let s = parse_string (rdr)?;
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constants.push (s.into ());
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}
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let upvalue_count = parse_int (rdr)? as usize;
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for _ in 0..upvalue_count {
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// Just ignore these
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for _ in 0..3 {
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parse_byte (rdr)?;
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}
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}
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blocks.push (Block {
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constants,
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instructions,
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upvalue_count,
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});
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// Recursion
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// Subfunctions. PUC calls them protos.
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let protos_count = parse_int (rdr)?;
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for _ in 0..protos_count {
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parse_block (rdr, blocks)?;
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}
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// Skip over debug stuff
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// I think this is delta line numbers, e.g. most instructions
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// have 0, but when you go to a new source line it's 1+.
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let lineinfo_count = parse_int (rdr)?;
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for _ in 0..lineinfo_count {
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parse_byte (rdr)?;
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}
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// Absolute line info, didn't see that in my test files
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let abslineinfo_count = parse_int (rdr)?;
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assert_eq! (abslineinfo_count, 0);
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let local_count = parse_int (rdr)?;
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for _ in 0..local_count {
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parse_string(rdr)?;
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parse_int (rdr)?;
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parse_int (rdr)?;
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}
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let upvalue_count = parse_int (rdr)?;
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for _ in 0..upvalue_count {
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parse_string (rdr)?;
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}
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Some (())
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}
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pub fn parse_chunk <R: Read> (rdr: &mut R) -> Option <Chunk> {
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// Discard 32 bytes from the start of the file.
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// This is magic number, version number, etc.
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let mut hdr = [0u8; 32];
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rdr.read_exact (&mut hdr).ok ()?;
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let mut blocks = vec![];
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while let Some (_) = parse_block (rdr, &mut blocks) {
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//
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}
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Some (Chunk {
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blocks,
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})
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}
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#[cfg (test)]
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mod tests {
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#[test]
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fn parse_inst () {
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use super::Inst;
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for (input, expected) in [
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([0x51, 0x00, 0x00, 0x00], Inst::VarArgPrep (0)),
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([0x4f, 0x00, 0x00, 0x00], Inst::Closure (0, 0)),
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([0xcf, 0x00, 0x00, 0x00], Inst::Closure (1, 0)),
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([0x8b, 0x00, 0x00, 0x00], Inst::GetTabUp (1, 0, 0)),
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([0x03, 0x81, 0x00, 0x00], Inst::LoadK (2, 1)),
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([0xc4, 0x00, 0x02, 0x01], Inst::Call (1, 2, 1)),
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([0x80, 0x00, 0x00, 0x00], Inst::Move (1, 0)),
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([0xc4, 0x00, 0x01, 0x02], Inst::Call (1, 1, 2)),
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([0x0b, 0x01, 0x00, 0x00], Inst::GetTabUp (2, 0, 0)),
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([0x83, 0x01, 0x01, 0x00], Inst::LoadK (3, 2)),
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([0x44, 0x01, 0x02, 0x01], Inst::Call (2, 2, 1)),
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([0x0b, 0x01, 0x00, 0x00], Inst::GetTabUp (2, 0, 0)),
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([0x80, 0x01, 0x01, 0x00], Inst::Move (3, 1)),
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([0xc4, 0x01, 0x01, 0x00], Inst::Call (3, 1, 0)),
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([0x44, 0x01, 0x00, 0x01], Inst::Call (2, 0, 1)),
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([0x0b, 0x01, 0x00, 0x00], Inst::GetTabUp (2, 0, 0)),
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([0x83, 0x81, 0x01, 0x00], Inst::LoadK (3, 3)),
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([0x44, 0x01, 0x02, 0x01], Inst::Call (2, 2, 1)),
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([0x46, 0x01, 0x01, 0x01], Inst::Return (2, 1, 1, false)),
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([0x01, 0x00, 0x02, 0x80], Inst::LoadI (0, 5)),
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([0xc6, 0x80, 0x02, 0x00], Inst::Return (1, 2, 0, true)),
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([0x09, 0x00, 0x01, 0x00], Inst::GetUpVal (0, 1)),
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([0x48, 0x00, 0x02, 0x00], Inst::Return1 (0)),
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([0x47, 0x00, 0x01, 0x00], Inst::Return0),
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([0x8d, 0x00, 0x01, 0x01], Inst::GetI (1, 1, 1)),
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([0xbc, 0x00, 0x01, 0x00], Inst::EqK (1, 1, 0)),
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([0xb8, 0x02, 0x00, 0x80], Inst::Jmp (6)),
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([0x38, 0x02, 0x00, 0x80], Inst::Jmp (5)),
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] {
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let actual = super::parse_inst (input).unwrap ();
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assert_eq!(actual, expected);
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}
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}
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#[test]
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fn parse_nested_functions () {
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use std::io::Read;
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let bytecode = include_bytes! ("../test_vectors/functions.luac");
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{
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let mut rdr = std::io::Cursor::new (bytecode.clone ());
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let mut buf = [0u8; 32];
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rdr.read_exact (&mut buf).unwrap ();
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let mut blocks = vec! [];
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super::parse_block (&mut rdr, &mut blocks).unwrap ();
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assert_eq! (blocks [0].instructions.len (), 15);
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assert_eq! (blocks [1].instructions.len (), 6);
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assert_eq! (blocks [2].instructions.len (), 4);
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assert_eq! (blocks [3].instructions.len (), 4);
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assert_eq! (blocks [4].instructions.len (), 4);
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}
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if false {
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let mut rdr = std::io::Cursor::new (bytecode.clone ());
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let file = crate::loader::parse_chunk (&mut rdr).unwrap ();
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assert_eq! (file.blocks.len (), 5);
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}
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}
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}
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