use crate::bytecode::format::BytecodeHeader;
use crate::bytecode::instruction::Instruction;
use crate::bytecode::proto::{Constant, Proto, UpvalueDesc};
use crate::bytecode::verify::verify_proto;
use num_bigint::{BigInt, Sign};
pub fn deserialize(bytes: &[u8]) -> Result<Proto, String> {
let (header, mut cursor) = BytecodeHeader::parse(bytes)?;
let payload = &bytes[cursor..];
let actual_checksum = crate::bytecode::format::compute_crc32(payload);
if actual_checksum != header.checksum {
return Err(format!(
"bytecode integrity check failed: checksum mismatch (expected 0x{:08X}, got 0x{:08X})",
header.checksum, actual_checksum
));
}
let proto = read_proto(bytes, &mut cursor, 0, None)?;
verify_proto(&proto).map_err(|e| e.to_string())?;
Ok(proto)
}
fn read_u8(bytes: &[u8], cursor: &mut usize) -> Result<u8, String> {
if *cursor >= bytes.len() {
return Err("unexpected end of bytecode".to_string());
}
let val = bytes[*cursor];
*cursor += 1;
Ok(val)
}
fn read_u16(bytes: &[u8], cursor: &mut usize) -> Result<u16, String> {
if *cursor + 2 > bytes.len() {
return Err("unexpected end of bytecode".to_string());
}
let val = u16::from_le_bytes([bytes[*cursor], bytes[*cursor + 1]]);
*cursor += 2;
Ok(val)
}
fn read_i16(bytes: &[u8], cursor: &mut usize) -> Result<i16, String> {
if *cursor + 2 > bytes.len() {
return Err("unexpected end of bytecode".to_string());
}
let val = i16::from_le_bytes([bytes[*cursor], bytes[*cursor + 1]]);
*cursor += 2;
Ok(val)
}
fn read_u32(bytes: &[u8], cursor: &mut usize) -> Result<u32, String> {
if *cursor + 4 > bytes.len() {
return Err("unexpected end of bytecode".to_string());
}
let val = u32::from_le_bytes([
bytes[*cursor],
bytes[*cursor + 1],
bytes[*cursor + 2],
bytes[*cursor + 3],
]);
*cursor += 4;
Ok(val)
}
fn read_i32(bytes: &[u8], cursor: &mut usize) -> Result<i32, String> {
if *cursor + 4 > bytes.len() {
return Err("unexpected end of bytecode".to_string());
}
let val = i32::from_le_bytes([
bytes[*cursor],
bytes[*cursor + 1],
bytes[*cursor + 2],
bytes[*cursor + 3],
]);
*cursor += 4;
Ok(val)
}
fn read_f64(bytes: &[u8], cursor: &mut usize) -> Result<f64, String> {
if *cursor + 8 > bytes.len() {
return Err("unexpected end of bytecode".to_string());
}
let mut b = [0u8; 8];
b.copy_from_slice(&bytes[*cursor..*cursor + 8]);
*cursor += 8;
Ok(f64::from_le_bytes(b))
}
fn read_string(bytes: &[u8], cursor: &mut usize) -> Result<String, String> {
let len = read_u32(bytes, cursor)? as usize;
if *cursor + len > bytes.len() {
return Err("unexpected end of bytecode in string".to_string());
}
let s = std::str::from_utf8(&bytes[*cursor..*cursor + len])
.map_err(|e| format!("invalid utf-8: {}", e))?
.to_string();
*cursor += len;
Ok(s)
}
fn read_bigint(bytes: &[u8], cursor: &mut usize) -> Result<BigInt, String> {
let sign_byte = read_u8(bytes, cursor)?;
let sign = match sign_byte {
0 => Sign::Minus,
1 => Sign::NoSign,
2 => Sign::Plus,
_ => return Err("invalid bigint sign".to_string()),
};
let len = read_u32(bytes, cursor)? as usize;
if *cursor + len > bytes.len() {
return Err("unexpected end of bytecode in bigint".to_string());
}
let b = BigInt::from_bytes_le(sign, &bytes[*cursor..*cursor + len]);
*cursor += len;
Ok(b)
}
fn read_constant(bytes: &[u8], cursor: &mut usize) -> Result<Constant, String> {
let tag = read_u8(bytes, cursor)?;
match tag {
0 => Ok(Constant::Nil),
1 => {
let b = read_u8(bytes, cursor)? != 0;
Ok(Constant::Bool(b))
}
2 => {
let bi = read_bigint(bytes, cursor)?;
Ok(Constant::Int(bi))
}
3 => {
let f = read_f64(bytes, cursor)?;
Ok(Constant::Float(f))
}
4 => {
let s = read_string(bytes, cursor)?;
Ok(Constant::String(s))
}
_ => Err(format!("invalid constant tag: {}", tag)),
}
}
fn read_instruction(bytes: &[u8], cursor: &mut usize) -> Result<Instruction, String> {
let tag = read_u8(bytes, cursor)?;
match tag {
1 => Ok(Instruction::LoadNil {
dst: read_u8(bytes, cursor)?,
}),
2 => Ok(Instruction::LoadBool {
dst: read_u8(bytes, cursor)?,
val: read_u8(bytes, cursor)? != 0,
}),
3 => Ok(Instruction::LoadInt {
dst: read_u8(bytes, cursor)?,
val: read_i32(bytes, cursor)?,
}),
4 => Ok(Instruction::LoadK {
dst: read_u8(bytes, cursor)?,
k: read_u16(bytes, cursor)?,
}),
5 => Ok(Instruction::Move {
dst: read_u8(bytes, cursor)?,
src: read_u8(bytes, cursor)?,
}),
6 => Ok(Instruction::GetGlobal {
dst: read_u8(bytes, cursor)?,
name_k: read_u16(bytes, cursor)?,
}),
7 => Ok(Instruction::SetGlobal {
src: read_u8(bytes, cursor)?,
name_k: read_u16(bytes, cursor)?,
}),
8 => Ok(Instruction::GetUpval {
dst: read_u8(bytes, cursor)?,
upval_idx: read_u8(bytes, cursor)?,
}),
9 => Ok(Instruction::SetUpval {
src: read_u8(bytes, cursor)?,
upval_idx: read_u8(bytes, cursor)?,
}),
10 => Ok(Instruction::NewTable {
dst: read_u8(bytes, cursor)?,
array_cap: read_u8(bytes, cursor)?,
fields_cap: read_u8(bytes, cursor)?,
}),
11 => Ok(Instruction::GetTable {
dst: read_u8(bytes, cursor)?,
table: read_u8(bytes, cursor)?,
key: read_u8(bytes, cursor)?,
}),
12 => Ok(Instruction::SetTable {
table: read_u8(bytes, cursor)?,
key: read_u8(bytes, cursor)?,
val: read_u8(bytes, cursor)?,
}),
13 => Ok(Instruction::GetTableK {
dst: read_u8(bytes, cursor)?,
table: read_u8(bytes, cursor)?,
key_k: read_u16(bytes, cursor)?,
}),
14 => Ok(Instruction::SetTableK {
table: read_u8(bytes, cursor)?,
key_k: read_u16(bytes, cursor)?,
val: read_u8(bytes, cursor)?,
}),
15 => Ok(Instruction::AppendArray {
table: read_u8(bytes, cursor)?,
src: read_u8(bytes, cursor)?,
}),
16 => Ok(Instruction::Add {
dst: read_u8(bytes, cursor)?,
a: read_u8(bytes, cursor)?,
b: read_u8(bytes, cursor)?,
}),
17 => Ok(Instruction::Sub {
dst: read_u8(bytes, cursor)?,
a: read_u8(bytes, cursor)?,
b: read_u8(bytes, cursor)?,
}),
18 => Ok(Instruction::Mul {
dst: read_u8(bytes, cursor)?,
a: read_u8(bytes, cursor)?,
b: read_u8(bytes, cursor)?,
}),
19 => Ok(Instruction::Div {
dst: read_u8(bytes, cursor)?,
a: read_u8(bytes, cursor)?,
b: read_u8(bytes, cursor)?,
}),
20 => Ok(Instruction::IDiv {
dst: read_u8(bytes, cursor)?,
a: read_u8(bytes, cursor)?,
b: read_u8(bytes, cursor)?,
}),
21 => Ok(Instruction::Mod {
dst: read_u8(bytes, cursor)?,
a: read_u8(bytes, cursor)?,
b: read_u8(bytes, cursor)?,
}),
22 => Ok(Instruction::Pow {
dst: read_u8(bytes, cursor)?,
a: read_u8(bytes, cursor)?,
b: read_u8(bytes, cursor)?,
}),
23 => Ok(Instruction::BitAnd {
dst: read_u8(bytes, cursor)?,
a: read_u8(bytes, cursor)?,
b: read_u8(bytes, cursor)?,
}),
24 => Ok(Instruction::BitOr {
dst: read_u8(bytes, cursor)?,
a: read_u8(bytes, cursor)?,
b: read_u8(bytes, cursor)?,
}),
25 => Ok(Instruction::BitXor {
dst: read_u8(bytes, cursor)?,
a: read_u8(bytes, cursor)?,
b: read_u8(bytes, cursor)?,
}),
26 => Ok(Instruction::Shl {
dst: read_u8(bytes, cursor)?,
a: read_u8(bytes, cursor)?,
b: read_u8(bytes, cursor)?,
}),
27 => Ok(Instruction::Shr {
dst: read_u8(bytes, cursor)?,
a: read_u8(bytes, cursor)?,
b: read_u8(bytes, cursor)?,
}),
28 => Ok(Instruction::Concat {
dst: read_u8(bytes, cursor)?,
a: read_u8(bytes, cursor)?,
b: read_u8(bytes, cursor)?,
}),
29 => Ok(Instruction::Unm {
dst: read_u8(bytes, cursor)?,
src: read_u8(bytes, cursor)?,
}),
30 => Ok(Instruction::Not {
dst: read_u8(bytes, cursor)?,
src: read_u8(bytes, cursor)?,
}),
31 => Ok(Instruction::Len {
dst: read_u8(bytes, cursor)?,
src: read_u8(bytes, cursor)?,
}),
32 => Ok(Instruction::BitNot {
dst: read_u8(bytes, cursor)?,
src: read_u8(bytes, cursor)?,
}),
33 => Ok(Instruction::Coalesce {
dst: read_u8(bytes, cursor)?,
a: read_u8(bytes, cursor)?,
b: read_u8(bytes, cursor)?,
}),
34 => Ok(Instruction::Eq {
a: read_u8(bytes, cursor)?,
b: read_u8(bytes, cursor)?,
jump_if_false: read_i16(bytes, cursor)?,
}),
35 => Ok(Instruction::Ne {
a: read_u8(bytes, cursor)?,
b: read_u8(bytes, cursor)?,
jump_if_false: read_i16(bytes, cursor)?,
}),
36 => Ok(Instruction::Lt {
a: read_u8(bytes, cursor)?,
b: read_u8(bytes, cursor)?,
jump_if_false: read_i16(bytes, cursor)?,
}),
37 => Ok(Instruction::Le {
a: read_u8(bytes, cursor)?,
b: read_u8(bytes, cursor)?,
jump_if_false: read_i16(bytes, cursor)?,
}),
38 => Ok(Instruction::Gt {
a: read_u8(bytes, cursor)?,
b: read_u8(bytes, cursor)?,
jump_if_false: read_i16(bytes, cursor)?,
}),
39 => Ok(Instruction::Ge {
a: read_u8(bytes, cursor)?,
b: read_u8(bytes, cursor)?,
jump_if_false: read_i16(bytes, cursor)?,
}),
40 => Ok(Instruction::Test {
reg: read_u8(bytes, cursor)?,
jump_if_false: read_i16(bytes, cursor)?,
}),
41 => Ok(Instruction::Jump {
offset: read_i16(bytes, cursor)?,
}),
42 => Ok(Instruction::Call {
callee: read_u8(bytes, cursor)?,
argc: read_u8(bytes, cursor)?,
retc: read_u8(bytes, cursor)?,
}),
43 => Ok(Instruction::Return {
base: read_u8(bytes, cursor)?,
count: read_u8(bytes, cursor)?,
}),
44 => Ok(Instruction::Closure {
dst: read_u8(bytes, cursor)?,
proto_idx: read_u16(bytes, cursor)?,
}),
45 => Ok(Instruction::Vararg {
dst: read_u8(bytes, cursor)?,
count: read_u8(bytes, cursor)?,
}),
46 => Ok(Instruction::ForPrep {
base: read_u8(bytes, cursor)?,
jump: read_i16(bytes, cursor)?,
}),
47 => Ok(Instruction::ForLoop {
base: read_u8(bytes, cursor)?,
jump: read_i16(bytes, cursor)?,
}),
48 => Ok(Instruction::SetList {
table: read_u8(bytes, cursor)?,
base: read_u8(bytes, cursor)?,
count: read_u8(bytes, cursor)?,
}),
49 => Ok(Instruction::TForCall {
base: read_u8(bytes, cursor)?,
retc: read_u8(bytes, cursor)?,
}),
50 => Ok(Instruction::TForLoop {
base: read_u8(bytes, cursor)?,
jump: read_i16(bytes, cursor)?,
}),
51 => Ok(Instruction::LShl {
dst: read_u8(bytes, cursor)?,
a: read_u8(bytes, cursor)?,
b: read_u8(bytes, cursor)?,
}),
52 => Ok(Instruction::LShr {
dst: read_u8(bytes, cursor)?,
a: read_u8(bytes, cursor)?,
b: read_u8(bytes, cursor)?,
}),
53 => Ok(Instruction::GetImport {
dst: read_u8(bytes, cursor)?,
mod_k: read_u16(bytes, cursor)?,
field_k: read_u16(bytes, cursor)?,
site: read_u16(bytes, cursor)?,
}),
54 => Ok(Instruction::CloseUpval {
reg: read_u8(bytes, cursor)?,
}),
_ => Err(format!("unknown instruction tag: {}", tag)),
}
}
fn read_proto(
bytes: &[u8],
cursor: &mut usize,
depth: usize,
parent_source: Option<std::rc::Rc<str>>,
) -> Result<Proto, String> {
const MAX_PROTO_DEPTH: usize = 64;
if depth > MAX_PROTO_DEPTH {
return Err(format!(
"bytecode nested prototype depth limit ({}) exceeded",
MAX_PROTO_DEPTH
));
}
let has_name = read_u8(bytes, cursor)? != 0;
let name = if has_name {
Some(read_string(bytes, cursor)?)
} else {
None
};
let source: Option<std::rc::Rc<str>> = match read_u8(bytes, cursor)? {
0 => None,
1 => Some(read_string(bytes, cursor)?.into()),
2 => parent_source,
tag => return Err(format!("invalid source tag {}", tag)),
};
let num_params = read_u8(bytes, cursor)?;
let max_registers = read_u8(bytes, cursor)?;
let is_vararg = read_u8(bytes, cursor)? != 0;
let num_constants = read_u32(bytes, cursor)? as usize;
if num_constants > 65535 {
return Err(format!(
"proto constant pool too large: {} (max 65535)",
num_constants
));
}
let mut constants = Vec::with_capacity(num_constants);
for _ in 0..num_constants {
constants.push(read_constant(bytes, cursor)?);
}
let num_instructions = read_u32(bytes, cursor)? as usize;
if num_instructions > 0x10_0000 {
return Err(format!(
"proto instruction count too large: {} (max 1048576)",
num_instructions
));
}
let mut instructions = Vec::with_capacity(num_instructions);
for _ in 0..num_instructions {
instructions.push(read_instruction(bytes, cursor)?);
}
let num_protos = read_u32(bytes, cursor)? as usize;
if num_protos > 4096 {
return Err(format!(
"proto nested prototype count too large: {} (max 4096)",
num_protos
));
}
let mut protos = Vec::with_capacity(num_protos);
for _ in 0..num_protos {
protos.push(std::rc::Rc::new(read_proto(
bytes,
cursor,
depth + 1,
source.clone(),
)?));
}
let num_upvalues = read_u32(bytes, cursor)? as usize;
if num_upvalues > 255 {
return Err(format!(
"proto upvalue count too large: {} (max 255)",
num_upvalues
));
}
let mut upvalues = Vec::with_capacity(num_upvalues);
let mut upvalue_names = Vec::with_capacity(num_upvalues);
for _ in 0..num_upvalues {
let in_stack = read_u8(bytes, cursor)? != 0;
let index = read_u8(bytes, cursor)?;
upvalues.push(UpvalueDesc { in_stack, index });
upvalue_names.push(read_string(bytes, cursor)?);
}
let num_lines = read_u32(bytes, cursor)? as usize;
if num_lines > 0x10_0000 {
return Err(format!(
"proto line info too large: {} (max 1048576)",
num_lines
));
}
let mut lines = Vec::with_capacity(num_lines);
for _ in 0..num_lines {
lines.push(read_u32(bytes, cursor)?);
}
let num_locals = read_u32(bytes, cursor)? as usize;
if num_locals > 65535 {
return Err(format!(
"proto local variable count too large: {} (max 65535)",
num_locals
));
}
let mut local_names = Vec::with_capacity(num_locals);
for _ in 0..num_locals {
let name = read_string(bytes, cursor)?;
let reg = read_u8(bytes, cursor)?;
let from_pc = read_u32(bytes, cursor)?;
let to_pc = read_u32(bytes, cursor)?;
local_names.push(crate::bytecode::proto::LocalVarInfo {
name,
reg,
from_pc,
to_pc,
});
}
Ok(Proto {
name,
num_params,
max_registers,
is_vararg,
constants,
instructions,
protos,
upvalues,
lines,
local_names,
source,
upvalue_names,
cache: Default::default(),
})
}