From 65efb64cdf91b7cee439ea3dfddff6daa5e23da7 Mon Sep 17 00:00:00 2001 From: Erin Date: Tue, 25 Jul 2023 22:44:08 +0200 Subject: [PATCH] Commented valider --- hbvm/src/validate.rs | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-) diff --git a/hbvm/src/validate.rs b/hbvm/src/validate.rs index d81b2d58..24c042cd 100644 --- a/hbvm/src/validate.rs +++ b/hbvm/src/validate.rs @@ -25,8 +25,8 @@ pub struct Error { /// Perform bytecode validation. If it passes, the program should be /// sound to execute. pub fn validate(mut program: &[u8]) -> Result<(), Error> { - use hbbytecode::opcode::*; - + // Program has to end with 12 zeroes, if there is less than + // 12 bytes, program is invalid. if program.len() < 12 { return Err(Error { kind: ErrorKind::InvalidEnd, @@ -34,6 +34,7 @@ pub fn validate(mut program: &[u8]) -> Result<(), Error> { }); } + // Verify that program ends with 12 zeroes for (index, item) in program.iter().enumerate().skip(program.len() - 12) { if *item != 0 { return Err(Error { @@ -45,9 +46,14 @@ pub fn validate(mut program: &[u8]) -> Result<(), Error> { let start = program; loop { + use hbbytecode::opcode::*; + // Match on instruction types and perform necessary checks program = match program { + // End of program [] => return Ok(()), + + // Memory load/store cannot go out-of-bounds register array [LD..=ST, reg, _, _, _, _, _, _, _, _, count_0, count_1, ..] if usize::from(*reg) * 8 + usize::from(u16::from_le_bytes([*count_1, *count_0])) @@ -58,6 +64,8 @@ pub fn validate(mut program: &[u8]) -> Result<(), Error> { index: (program.as_ptr() as usize) - (start.as_ptr() as usize), }) } + + // Block register copy cannot go out-of-bounds register array [BRC, src, dst, count, ..] if src.checked_add(*count).is_none() || dst.checked_add(*count).is_none() => { @@ -66,6 +74,8 @@ pub fn validate(mut program: &[u8]) -> Result<(), Error> { index: (program.as_ptr() as usize) - (start.as_ptr() as usize), }) } + + // Valid instructions [UN | NOP | ECALL, rest @ ..] | [DIR | DIRF, _, _, _, _, rest @ ..] | [ADD..=CMPU | BRC | ADDF..=MULF, _, _, _, rest @ ..] @@ -74,6 +84,8 @@ pub fn validate(mut program: &[u8]) -> Result<(), Error> { | [ADDI..=XORI | CMPI..=CMPUI | BMC | JAL..=JGTU | ADDFI..=MULFI, _, _, _, _, _, _, _, _, _, _, rest @ ..] | [SLI..=SRSI, _, _, _, _, rest @ ..] | [LD..=ST, _, _, _, _, _, _, _, _, _, _, _, _, rest @ ..] => rest, + + // The rest _ => { return Err(Error { kind: ErrorKind::InvalidInstruction,