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Convert instruction decoding panics into runtime errors #10

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65952e7
replace panic with err value in instruction decoding
epakskape Jun 14, 2020
ebe6990
remove unimplemented
epakskape Jun 14, 2020
adb4128
cleanup warnings
Jun 16, 2020
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2 changes: 1 addition & 1 deletion Cargo.toml
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Original file line number Diff line number Diff line change
Expand Up @@ -11,5 +11,5 @@ license = "MIT"
[dependencies]
arrayvec = "0.3.23"
byteorder = "1"
lazy_static = "0.2"
lazy_static = "1.4"
matches = "0.1"
83 changes: 45 additions & 38 deletions src/decoding.rs
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Expand Up @@ -226,13 +226,13 @@ impl<T: Read> InstructionReader<T> {

// We can assume that we have a ModR/M byte if we've gotten to this point as it
// would have errored out if we needed one but didn't read one.
Ok(match op_def.encoding {
let res: Result<Operand, InstructionDecodingError> = match op_def.encoding {
OperandEncoding::ModRmReg =>
if let OperandType::Reg(reg_type) = op_def.op_type {
Operand::Direct(Reg::from_code_reg_type(
Ok(Operand::Direct(Reg::from_code_reg_type(
buffer.mod_rm_reg.unwrap(), reg_type, size, buffer.has_rex())
.ok_or(InstructionDecodingError::InvalidInstruction)?)
} else { panic!("Invalid operand definition."); },
.ok_or(InstructionDecodingError::InvalidInstruction)?))
} else { Err(InstructionDecodingError::InvalidOperand) },

OperandEncoding::ModRmRm => { // TODO Handle MIB
let reg_type = if let OperandType::Reg(reg_type) = op_def.op_type { reg_type }
Expand All @@ -241,87 +241,88 @@ impl<T: Read> InstructionReader<T> {
{ Some(reg_type) } else { None }).next().unwrap_or(RegType::General)
} else { RegType::General };
self.rm_helper(buffer, op_def,
|c| Reg::from_code_reg_type(c, reg_type, size, buffer.has_rex()))?
|c| Reg::from_code_reg_type(c, reg_type, size, buffer.has_rex()))
},

OperandEncoding::Vex =>
if let OperandType::Reg(reg_type) = op_def.op_type {
Operand::Direct(Reg::from_code_reg_type(
Ok(Operand::Direct(Reg::from_code_reg_type(
buffer.vex_operand.unwrap(), reg_type, size, buffer.has_rex())
.ok_or(InstructionDecodingError::InvalidInstruction)?)
} else { panic!("Invalid operand definition."); },
.ok_or(InstructionDecodingError::InvalidInstruction)?))
} else { Err(InstructionDecodingError::InvalidOperand) },

OperandEncoding::Imm =>
match op_def.op_type {
OperandType::Reg(reg_type) =>
Operand::Direct(Reg::from_code_reg_type(
Ok(Operand::Direct(Reg::from_code_reg_type(
self.expect_byte()? >> 4, reg_type, size, buffer.has_rex())
.ok_or(InstructionDecodingError::InvalidInstruction)?),
.ok_or(InstructionDecodingError::InvalidInstruction)?)),
OperandType::Imm => match op_def.size {
OperandSize::Byte => self.expect_byte().map(|b| Operand::Literal8(b))?,
OperandSize::Byte => self.expect_byte().map(|b| Operand::Literal8(b)),
OperandSize::Word =>
(0..2).fold(Ok(0), |acc, n| acc.and_then(|a| self.expect_byte().map(
|b| a | ((b as u16) << (8*n) )))).map(|b| Operand::Literal16(b))?,
|b| a | ((b as u16) << (8*n) )))).map(|b| Operand::Literal16(b)),
OperandSize::Dword =>
(0..4).fold(Ok(0), |acc, n| acc.and_then(|a| self.expect_byte().map(
|b| a | ((b as u32) << (8*n) )))).map(|b| Operand::Literal32(b))?,
|b| a | ((b as u32) << (8*n) )))).map(|b| Operand::Literal32(b)),
OperandSize::Far16 => { // 16:16
let addr = (0..2).fold(Ok(0), |acc, n| acc.and_then(|a|
self.expect_byte().map(|b| a | ((b as u16) << (8*n) ))))?;
let segment = (0..2).fold(Ok(0), |acc, n| acc.and_then(|a|
self.expect_byte().map(|b| a | ((b as u16) << (8*n) ))))?;
Operand::MemoryAndSegment16(segment, addr)
Ok(Operand::MemoryAndSegment16(segment, addr))
},
OperandSize::Far32 => { // 16:32
let addr = (0..4).fold(Ok(0), |acc, n| acc.and_then(|a|
self.expect_byte().map(|b| a | ((b as u32) << (8*n) ))))?;
let segment = (0..2).fold(Ok(0), |acc, n| acc.and_then(|a|
self.expect_byte().map(|b| a | ((b as u16) << (8*n) ))))?;
Operand::MemoryAndSegment32(segment, addr)
Ok(Operand::MemoryAndSegment32(segment, addr))
},
_ => unimplemented!()
_ => Err(InstructionDecodingError::NotImplemented)
},
OperandType::Rel(_) =>
Operand::Offset(
Ok(Operand::Offset(
(0..op_def.size.bits() >> 3).fold(Ok(0), |acc, n| acc.and_then(|a|
self.expect_byte().map(|b| a | ((b as u64) << (8*n) ))))?,
None, None),
_ => panic!("Bad instruction definition.")
None, None)),
_ => Err(InstructionDecodingError::InvalidInstruction)
},

OperandEncoding::OpcodeAddend =>
if let OperandType::Reg(reg_type) = op_def.op_type {
Operand::Direct(Reg::from_code_reg_type(
Ok(Operand::Direct(Reg::from_code_reg_type(
buffer.primary_opcode & 0x7, reg_type, size, buffer.has_rex())
.ok_or(InstructionDecodingError::InvalidInstruction)?)
} else { panic!("Invalid operand definition."); },
.ok_or(InstructionDecodingError::InvalidInstruction)?))
} else { Err(InstructionDecodingError::InvalidOperand) },

OperandEncoding::Offset =>
Operand::Offset(match addr_size {
OperandSize::Word => self.read_disp16()? as u64,
OperandSize::Dword => self.read_disp32()? as u64,
// OperandSize::Qword => self.read_disp64()? as u64,
_ => unimplemented!() // TODO?
}, Some(op_def.size), None),
match addr_size {
OperandSize::Word => Ok(Operand::Offset(self.read_disp16()? as u64, Some(op_def.size), None)),
OperandSize::Dword => Ok(Operand::Offset(self.read_disp32()? as u64, Some(op_def.size), None)),
_ => Err(InstructionDecodingError::NotImplemented) // TODO?
},

OperandEncoding::Mib => unimplemented!(),
OperandEncoding::Mib => Err(InstructionDecodingError::NotImplemented),

OperandEncoding::Fixed =>
match op_def.op_type {
OperandType::Fixed(FixedOperand::Reg(reg)) =>
Operand::Direct(reg),
Ok(Operand::Direct(reg)),
OperandType::Fixed(FixedOperand::Constant(v)) =>
match op_def.size {
OperandSize::Unsized |
OperandSize::Byte => Operand::Literal8(v as u8),
OperandSize::Word => Operand::Literal16(v as u16),
OperandSize::Dword => Operand::Literal32(v),
OperandSize::Qword => Operand::Literal64(v as u64),
_ => panic!("Invalid operand definition.")
OperandSize::Byte => Ok(Operand::Literal8(v as u8)),
OperandSize::Word => Ok(Operand::Literal16(v as u16)),
OperandSize::Dword => Ok(Operand::Literal32(v)),
OperandSize::Qword => Ok(Operand::Literal64(v as u64)),
_ => Err(InstructionDecodingError::InvalidOperand)
},
_ => panic!("Invalid operand definition.")
_ => Err(InstructionDecodingError::InvalidOperand)
}
})
};

res
}

fn read_disp8(&mut self) -> Result<u8, InstructionDecodingError> {
Expand Down Expand Up @@ -591,6 +592,12 @@ pub enum InstructionDecodingError {
// InvalidInstruction - Generic error for an invalid instruction.
InvalidInstruction,

// InvalidOperand - Generic error for an invalid operand.
InvalidOperand,

// UnknownOpcode - Indicates that an unrecognized opcode was encountered.
UnknownOpcode
UnknownOpcode,

// NotImplemented - Indicates that the suport required to decode is not implemented.
NotImplemented
}
2 changes: 1 addition & 1 deletion src/instruction_def.rs
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Expand Up @@ -53,7 +53,7 @@ pub fn load_instructions(map: &mut HashMap<Mnemonic, Vec<&'static InstructionDef
let new_list = Vec::new();
map.insert(instr.mnemonic, new_list);
};
let mut list = map.get_mut(&instr.mnemonic).unwrap();
let list = map.get_mut(&instr.mnemonic).unwrap();
list.push(&instr);
}
}
Expand Down