fuel-vm 0.66.3

FuelVM interpreter.
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 fuel_tx::{
    Chargeable,
    Input,
    Output,
    ValidityError,
    field,
    input::{
        coin::{
            CoinPredicate,
            CoinSigned,
        },
        message::{
            MessageCoinPredicate,
            MessageCoinSigned,
            MessageDataPredicate,
            MessageDataSigned,
        },
    },
};
use fuel_types::{
    AssetId,
    Word,
};

use alloc::collections::BTreeMap;
use fuel_tx::policies::PolicyType;

pub(crate) fn initial_free_balances<T>(
    tx: &T,
    base_asset_id: &AssetId,
) -> Result<AvailableBalances, ValidityError>
where
    T: Chargeable + field::Inputs + field::Outputs,
{
    let (mut non_retryable_balances, retryable_balance) =
        add_up_input_balances(tx, base_asset_id).ok_or(ValidityError::BalanceOverflow)?;

    let max_fee = tx
        .policies()
        .get(PolicyType::MaxFee)
        .ok_or(ValidityError::TransactionMaxFeeNotSet)?;
    deduct_max_fee_from_base_asset(&mut non_retryable_balances, base_asset_id, max_fee)?;

    reduce_free_balances_by_coin_outputs(&mut non_retryable_balances, tx)?;

    Ok(AvailableBalances {
        non_retryable_balances,
        retryable_balance,
    })
}

/// Returns None if any of the balances would overflow.
fn add_up_input_balances<T: field::Inputs>(
    transaction: &T,
    base_asset_id: &AssetId,
) -> Option<(BTreeMap<AssetId, Word>, Word)> {
    let mut non_retryable_balances = BTreeMap::<AssetId, Word>::new();
    // The sum of [`AssetId::Base`] from metadata messages.
    let mut retryable_balance: Word = 0;

    // Add up all the inputs for each asset ID
    for input in transaction.inputs().iter() {
        match input {
            // Sum coin inputs
            Input::CoinPredicate(CoinPredicate {
                asset_id, amount, ..
            })
            | Input::CoinSigned(CoinSigned {
                asset_id, amount, ..
            }) => {
                let balance = non_retryable_balances.entry(*asset_id).or_default();
                *balance = (*balance).checked_add(*amount)?;
            }
            // Sum message coin inputs
            Input::MessageCoinSigned(MessageCoinSigned { amount, .. })
            | Input::MessageCoinPredicate(MessageCoinPredicate { amount, .. }) => {
                let balance = non_retryable_balances.entry(*base_asset_id).or_default();
                *balance = (*balance).checked_add(*amount)?;
            }
            // Sum data messages
            Input::MessageDataSigned(MessageDataSigned { amount, .. })
            | Input::MessageDataPredicate(MessageDataPredicate { amount, .. }) => {
                retryable_balance = retryable_balance.checked_add(*amount)?;
            }
            Input::Contract(_) => {}
        }
    }

    Some((non_retryable_balances, retryable_balance))
}

fn deduct_max_fee_from_base_asset(
    non_retryable_balances: &mut BTreeMap<AssetId, Word>,
    base_asset_id: &AssetId,
    max_fee: Word,
) -> Result<(), ValidityError> {
    let base_asset_balance = non_retryable_balances.entry(*base_asset_id).or_default();
    *base_asset_balance = base_asset_balance.checked_sub(max_fee).ok_or(
        ValidityError::InsufficientFeeAmount {
            expected: max_fee,
            provided: *base_asset_balance,
        },
    )?;

    Ok(())
}

fn reduce_free_balances_by_coin_outputs(
    non_retryable_balances: &mut BTreeMap<AssetId, Word>,
    transaction: &impl field::Outputs,
) -> Result<(), ValidityError> {
    // reduce free balances by coin outputs
    for (asset_id, amount) in
        transaction
            .outputs()
            .iter()
            .filter_map(|output| match output {
                Output::Coin {
                    asset_id, amount, ..
                } => Some((asset_id, amount)),
                _ => None,
            })
    {
        let balance = non_retryable_balances.get_mut(asset_id).ok_or(
            ValidityError::TransactionOutputCoinAssetIdNotFound(*asset_id),
        )?;
        *balance = balance.checked_sub(*amount).ok_or(
            ValidityError::InsufficientInputAmount {
                asset: *asset_id,
                expected: *amount,
                provided: *balance,
            },
        )?;
    }

    Ok(())
}

pub(crate) struct AvailableBalances {
    pub(crate) non_retryable_balances: BTreeMap<AssetId, Word>,
    pub(crate) retryable_balance: Word,
}