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

//! Backtrace implementation to track script errors.
//!
//! As of the moment, doesn't support predicates.

use crate::call::CallFrame;
use crate::consts::*;
use crate::interpreter::Interpreter;

use fuel_tx::{CheckedTransaction, ScriptExecutionResult};
use fuel_types::{ContractId, Word};

#[derive(Debug)]
/// Runtime description derived from a VM error.
pub struct Backtrace {
    call_stack: Vec<CallFrame>,
    contract: ContractId,
    registers: [Word; VM_REGISTER_COUNT],
    memory: Vec<u8>,
    result: ScriptExecutionResult,
    tx: CheckedTransaction,
}

impl Backtrace {
    /// Create a backtrace from a vm instance and instruction result.
    ///
    /// This isn't copy-free and shouldn't be provided by default.
    pub fn from_vm_error<S>(vm: &Interpreter<S>, result: ScriptExecutionResult) -> Self {
        let call_stack = vm.call_stack().to_owned();
        let contract = vm.internal_contract_or_default();
        let memory = vm.memory().to_owned();
        let tx = vm.checked_transaction().clone();
        let mut registers = [0; VM_REGISTER_COUNT];

        registers.copy_from_slice(vm.registers());

        Self {
            call_stack,
            contract,
            registers,
            memory,
            result,
            tx,
        }
    }

    /// Call stack of the VM when the error occurred.
    pub fn call_stack(&self) -> &[CallFrame] {
        self.call_stack.as_slice()
    }

    /// Last contract of the context when the error occurred.
    pub const fn contract(&self) -> &ContractId {
        &self.contract
    }

    /// Register set when the error occurred.
    pub const fn registers(&self) -> &[Word] {
        &self.registers
    }

    /// Memory of the VM when the error occurred.
    pub fn memory(&self) -> &[u8] {
        self.memory.as_slice()
    }

    /// [`ScriptExecutionResult`] of the error that caused this backtrace.
    pub const fn result(&self) -> &ScriptExecutionResult {
        &self.result
    }

    /// [`fuel_tx::Transaction`] state when the error occurred.
    pub const fn tx(&self) -> &CheckedTransaction {
        &self.tx
    }

    /// Expose the internal attributes of the backtrace.
    pub fn into_inner(
        self,
    ) -> (
        Vec<CallFrame>,
        ContractId,
        [Word; VM_REGISTER_COUNT],
        Vec<u8>,
        ScriptExecutionResult,
        CheckedTransaction,
    ) {
        let Self {
            call_stack,
            contract,
            registers,
            memory,
            result,
            tx,
        } = self;

        (call_stack, contract, registers, memory, result, tx)
    }
}