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
143
144

//! Trap codes describing the reason for a trap.

use core::fmt::{self, Display, Formatter};
use core::str::FromStr;
#[cfg(feature = "enable-serde")]
use serde_derive::{Deserialize, Serialize};

/// A trap code describing the reason for a trap.
///
/// All trap instructions have an explicit trap code.
#[derive(Clone, Copy, PartialEq, Eq, Debug, Hash)]
#[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
pub enum TrapCode {
    /// The current stack space was exhausted.
    StackOverflow,

    /// A `heap_addr` instruction detected an out-of-bounds error.
    ///
    /// Note that not all out-of-bounds heap accesses are reported this way;
    /// some are detected by a segmentation fault on the heap unmapped or
    /// offset-guard pages.
    HeapOutOfBounds,

    /// A wasm atomic operation was presented with a not-naturally-aligned linear-memory address.
    HeapMisaligned,

    /// A `table_addr` instruction detected an out-of-bounds error.
    TableOutOfBounds,

    /// Indirect call to a null table entry.
    IndirectCallToNull,

    /// Signature mismatch on indirect call.
    BadSignature,

    /// An integer arithmetic operation caused an overflow.
    IntegerOverflow,

    /// An integer division by zero.
    IntegerDivisionByZero,

    /// Failed float-to-int conversion.
    BadConversionToInteger,

    /// Code that was supposed to have been unreachable was reached.
    UnreachableCodeReached,

    /// Execution has potentially run too long and may be interrupted.
    /// This trap is resumable.
    Interrupt,

    /// A user-defined trap code.
    User(u16),

    /// A null reference was encountered which was required to be non-null.
    NullReference,
}

impl TrapCode {
    /// Returns a slice of all traps except `TrapCode::User` traps
    pub const fn non_user_traps() -> &'static [TrapCode] {
        &[
            TrapCode::StackOverflow,
            TrapCode::HeapOutOfBounds,
            TrapCode::HeapMisaligned,
            TrapCode::TableOutOfBounds,
            TrapCode::IndirectCallToNull,
            TrapCode::BadSignature,
            TrapCode::IntegerOverflow,
            TrapCode::IntegerDivisionByZero,
            TrapCode::BadConversionToInteger,
            TrapCode::UnreachableCodeReached,
            TrapCode::Interrupt,
            TrapCode::NullReference,
        ]
    }
}

impl Display for TrapCode {
    fn fmt(&self, f: &mut Formatter) -> fmt::Result {
        use self::TrapCode::*;
        let identifier = match *self {
            StackOverflow => "stk_ovf",
            HeapOutOfBounds => "heap_oob",
            HeapMisaligned => "heap_misaligned",
            TableOutOfBounds => "table_oob",
            IndirectCallToNull => "icall_null",
            BadSignature => "bad_sig",
            IntegerOverflow => "int_ovf",
            IntegerDivisionByZero => "int_divz",
            BadConversionToInteger => "bad_toint",
            UnreachableCodeReached => "unreachable",
            Interrupt => "interrupt",
            User(x) => return write!(f, "user{}", x),
            NullReference => "null_reference",
        };
        f.write_str(identifier)
    }
}

impl FromStr for TrapCode {
    type Err = ();

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        use self::TrapCode::*;
        match s {
            "stk_ovf" => Ok(StackOverflow),
            "heap_oob" => Ok(HeapOutOfBounds),
            "heap_misaligned" => Ok(HeapMisaligned),
            "table_oob" => Ok(TableOutOfBounds),
            "icall_null" => Ok(IndirectCallToNull),
            "bad_sig" => Ok(BadSignature),
            "int_ovf" => Ok(IntegerOverflow),
            "int_divz" => Ok(IntegerDivisionByZero),
            "bad_toint" => Ok(BadConversionToInteger),
            "unreachable" => Ok(UnreachableCodeReached),
            "interrupt" => Ok(Interrupt),
            "null_reference" => Ok(NullReference),
            _ if s.starts_with("user") => s[4..].parse().map(User).map_err(|_| ()),
            _ => Err(()),
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use alloc::string::ToString;

    #[test]
    fn display() {
        for r in TrapCode::non_user_traps() {
            let tc = *r;
            assert_eq!(tc.to_string().parse(), Ok(tc));
        }
        assert_eq!("bogus".parse::<TrapCode>(), Err(()));

        assert_eq!(TrapCode::User(17).to_string(), "user17");
        assert_eq!("user22".parse(), Ok(TrapCode::User(22)));
        assert_eq!("user".parse::<TrapCode>(), Err(()));
        assert_eq!("user-1".parse::<TrapCode>(), Err(()));
        assert_eq!("users".parse::<TrapCode>(), Err(()));
    }
}