86 lines
2.8 KiB
Rust
86 lines
2.8 KiB
Rust
//! Validate if program is sound to execute
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/// Program validation error kind
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#[derive(Clone, Copy, Debug, PartialEq, Eq)]
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pub enum ErrorKind {
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/// Unknown opcode
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InvalidInstruction,
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/// VM doesn't implement this valid opcode
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Unimplemented,
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/// Attempted to copy over register boundary
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RegisterArrayOverflow,
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/// Program is not validly terminated
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InvalidEnd,
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}
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/// Error
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#[derive(Clone, Copy, Debug, PartialEq, Eq)]
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pub struct Error {
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/// Kind
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pub kind: ErrorKind,
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/// Location in bytecode
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pub index: usize,
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}
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/// Perform bytecode validation. If it passes, the program should be
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/// sound to execute.
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pub fn validate(mut program: &[u8]) -> Result<(), Error> {
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use hbbytecode::opcode::*;
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if program.len() < 12 {
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return Err(Error {
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kind: ErrorKind::InvalidEnd,
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index: 0,
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});
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}
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for (index, item) in program.iter().enumerate().skip(program.len() - 12) {
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if *item != 0 {
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return Err(Error {
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kind: ErrorKind::InvalidEnd,
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index,
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});
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}
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}
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let start = program;
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loop {
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// Match on instruction types and perform necessary checks
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program = match program {
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[] => return Ok(()),
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[LD..=ST, reg, _, _, _, _, _, _, _, _, count_0, count_1, ..]
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if usize::from(*reg) * 8
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+ usize::from(u16::from_le_bytes([*count_0, *count_1]))
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> 2048 =>
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{
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return Err(Error {
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kind: ErrorKind::RegisterArrayOverflow,
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index: (program.as_ptr() as usize) - (start.as_ptr() as usize),
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})
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}
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[BRC, src, dst, count, ..]
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if src.checked_add(*count).is_none() || dst.checked_add(*count).is_none() =>
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{
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return Err(Error {
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kind: ErrorKind::RegisterArrayOverflow,
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index: (program.as_ptr() as usize) - (start.as_ptr() as usize),
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})
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}
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[UN | NOP | ECALL, rest @ ..]
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| [DIR | DIRF, _, _, _, _, rest @ ..]
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| [ADD..=CMPU | BRC | ADDF..=MULF, _, _, _, rest @ ..]
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| [NEG..=NOT | CP..=SWA | NEGF..=FTI, _, _, rest @ ..]
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| [LI, _, _, _, _, _, _, _, _, _, rest @ ..]
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| [ADDI..=XORI | CMPI..=CMPUI | BMC | JAL..=JGTU | ADDFI..=MULFI, _, _, _, _, _, _, _, _, _, _, rest @ ..]
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| [SLI..=SRSI, _, _, _, _, rest @ ..]
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| [LD..=ST, _, _, _, _, _, _, _, _, _, _, _, _, rest @ ..] => rest,
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_ => {
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return Err(Error {
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kind: ErrorKind::InvalidInstruction,
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index: (program.as_ptr() as usize) - (start.as_ptr() as usize),
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})
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}
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}
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}
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}
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