neo-decompiler 0.6.2

Minimal tooling for inspecting Neo N3 NEF bytecode
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142

use super::*;
use crate::instruction::Operand;

#[test]
fn decodes_simple_sequence() {
    let bytecode = [0x10, 0x11, 0x9E, 0x40];
    let instructions = Disassembler::new()
        .disassemble(&bytecode)
        .expect("disassembly succeeds");

    let mnemonics: Vec<_> = instructions
        .iter()
        .map(|ins| ins.opcode.mnemonic())
        .collect();
    assert_eq!(mnemonics, vec!["PUSH0", "PUSH1", "ADD", "RET"]);
}

#[test]
fn errors_on_unknown_opcode() {
    let bytecode = [0xFF];
    let err = Disassembler::with_unknown_handling(UnknownHandling::Error)
        .disassemble(&bytecode)
        .unwrap_err();
    assert!(matches!(
        err,
        crate::error::Error::Disassembly(DisassemblyError::UnknownOpcode {
            opcode: 0xFF,
            offset: 0
        })
    ));
}

#[test]
fn permits_unknown_opcode_when_configured() {
    let bytecode = [0xFF, 0x40];
    let instructions = Disassembler::with_unknown_handling(UnknownHandling::Permit)
        .disassemble(&bytecode)
        .expect("disassembly succeeds in tolerant mode");

    assert_eq!(instructions.len(), 2);
    assert!(matches!(instructions[0].opcode, OpCode::Unknown(0xFF)));
    assert_eq!(instructions[1].opcode, OpCode::Ret);
}

#[test]
fn reports_warning_for_unknown_opcode_in_tolerant_mode() {
    let bytecode = [0xFF, 0x40];
    let output = Disassembler::with_unknown_handling(UnknownHandling::Permit)
        .disassemble_with_warnings(&bytecode)
        .expect("disassembly succeeds in tolerant mode");

    assert_eq!(output.instructions.len(), 2);
    assert_eq!(output.warnings.len(), 1);
    assert!(matches!(
        output.warnings[0],
        DisassemblyWarning::UnknownOpcode {
            opcode: 0xFF,
            offset: 0
        }
    ));
}

#[test]
fn fails_on_truncated_operand() {
    let bytecode = [0x01, 0x00];
    let err = Disassembler::new().disassemble(&bytecode).unwrap_err();
    assert!(matches!(
        err,
        crate::error::Error::Disassembly(DisassemblyError::UnexpectedEof { offset: 0 })
    ));
}

#[test]
fn decodes_calla_no_operand() {
    // CALLA (0x36) takes no inline operand — it pops a Pointer from the stack.
    let bytecode = [0x36];
    let instructions = Disassembler::new()
        .disassemble(&bytecode)
        .expect("disassembly succeeds");

    assert_eq!(instructions.len(), 1);
    assert_eq!(instructions[0].opcode, OpCode::CallA);
    assert_eq!(instructions[0].operand, None);
}

#[test]
fn decodes_pushdata2() {
    let bytecode = [0x0D, 0x04, 0x00, 0xDE, 0xAD, 0xBE, 0xEF];
    let instruction = Disassembler::new().disassemble(&bytecode).expect("success")[0].clone();
    assert_eq!(instruction.opcode.mnemonic(), "PUSHDATA2");
    assert_eq!(instruction.offset, 0);
    assert_eq!(
        instruction.operand,
        Some(Operand::Bytes(vec![0xDE, 0xAD, 0xBE, 0xEF]))
    );
    assert_eq!(instruction.opcode, OpCode::Pushdata2);
}

#[test]
fn decodes_jump_long() {
    let bytecode = [0x23, 0x34, 0x12, 0x00, 0x00];
    let instruction = Disassembler::new().disassemble(&bytecode).expect("success")[0].clone();
    assert_eq!(instruction.opcode, OpCode::Jmp_L);
    assert_eq!(instruction.operand, Some(Operand::Jump32(0x1234)));
    assert_eq!(instruction.offset, 0);
}

#[test]
fn decodes_syscall_operand_with_name() {
    // System.Runtime.Platform
    let bytecode = [0x41, 0xB2, 0x79, 0xFC, 0xF6];
    let instruction = Disassembler::new().disassemble(&bytecode).expect("success")[0].clone();
    assert_eq!(instruction.opcode, OpCode::Syscall);
    let operand = instruction.operand.expect("syscall operand");
    assert_eq!(operand.to_string(), "System.Runtime.Platform (0xF6FC79B2)");
}

#[test]
fn pushdata4_excessive_length_returns_operand_too_large() {
    // PUSHDATA4 length is little-endian u32.
    // MAX_OPERAND_LEN is 1_048_576, so request one more than that.
    let bytecode = [0x0E, 0x01, 0x00, 0x10, 0x00];
    let err = Disassembler::new().disassemble(&bytecode).unwrap_err();
    assert!(matches!(
        err,
        crate::error::Error::Disassembly(DisassemblyError::OperandTooLarge {
            offset: 0,
            len: 1_048_577
        })
    ));
}

#[test]
fn pushdata4_truncated_payload_returns_unexpected_eof() {
    // PUSHDATA4 claims a 4-byte payload but only provides 2 bytes.
    let bytecode = [0x0E, 0x04, 0x00, 0x00, 0x00, 0xAA, 0xBB];
    let err = Disassembler::new().disassemble(&bytecode).unwrap_err();
    assert!(matches!(
        err,
        crate::error::Error::Disassembly(DisassemblyError::UnexpectedEof { offset: 0 })
    ));
}