1 //! Trap codes describing the reason for a trap.
2 
3 use core::fmt::{self, Display, Formatter};
4 use core::str::FromStr;
5 #[cfg(feature = "enable-serde")]
6 use serde_derive::{Deserialize, Serialize};
7 
8 /// A trap code describing the reason for a trap.
9 ///
10 /// All trap instructions have an explicit trap code.
11 #[derive(Clone, Copy, PartialEq, Eq, Debug, Hash)]
12 #[cfg_attr(feature = "enable-serde", derive(Serialize, Deserialize))]
13 pub enum TrapCode {
14     /// The current stack space was exhausted.
15     StackOverflow,
16 
17     /// A `heap_addr` instruction detected an out-of-bounds error.
18     ///
19     /// Note that not all out-of-bounds heap accesses are reported this way;
20     /// some are detected by a segmentation fault on the heap unmapped or
21     /// offset-guard pages.
22     HeapOutOfBounds,
23 
24     /// A wasm atomic operation was presented with a not-naturally-aligned linear-memory address.
25     HeapMisaligned,
26 
27     /// A `table_addr` instruction detected an out-of-bounds error.
28     TableOutOfBounds,
29 
30     /// Indirect call to a null table entry.
31     IndirectCallToNull,
32 
33     /// Signature mismatch on indirect call.
34     BadSignature,
35 
36     /// An integer arithmetic operation caused an overflow.
37     IntegerOverflow,
38 
39     /// An integer division by zero.
40     IntegerDivisionByZero,
41 
42     /// Failed float-to-int conversion.
43     BadConversionToInteger,
44 
45     /// Code that was supposed to have been unreachable was reached.
46     UnreachableCodeReached,
47 
48     /// Execution has potentially run too long and may be interrupted.
49     Interrupt,
50 
51     /// A user-defined trap code.
52     User(u16),
53 
54     /// A null reference was encountered which was required to be non-null.
55     NullReference,
56 
57     /// A null `i31ref` was encountered which was required to be non-null.
58     NullI31Ref,
59 }
60 
61 impl TrapCode {
62     /// Returns a slice of all traps except `TrapCode::User` traps
63     pub const fn non_user_traps() -> &'static [TrapCode] {
64         &[
65             TrapCode::StackOverflow,
66             TrapCode::HeapOutOfBounds,
67             TrapCode::HeapMisaligned,
68             TrapCode::TableOutOfBounds,
69             TrapCode::IndirectCallToNull,
70             TrapCode::BadSignature,
71             TrapCode::IntegerOverflow,
72             TrapCode::IntegerDivisionByZero,
73             TrapCode::BadConversionToInteger,
74             TrapCode::UnreachableCodeReached,
75             TrapCode::Interrupt,
76             TrapCode::NullReference,
77         ]
78     }
79 }
80 
81 impl Display for TrapCode {
82     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
83         use self::TrapCode::*;
84         let identifier = match *self {
85             StackOverflow => "stk_ovf",
86             HeapOutOfBounds => "heap_oob",
87             HeapMisaligned => "heap_misaligned",
88             TableOutOfBounds => "table_oob",
89             IndirectCallToNull => "icall_null",
90             BadSignature => "bad_sig",
91             IntegerOverflow => "int_ovf",
92             IntegerDivisionByZero => "int_divz",
93             BadConversionToInteger => "bad_toint",
94             UnreachableCodeReached => "unreachable",
95             Interrupt => "interrupt",
96             User(x) => return write!(f, "user{x}"),
97             NullReference => "null_reference",
98             NullI31Ref => "null_i31ref",
99         };
100         f.write_str(identifier)
101     }
102 }
103 
104 impl FromStr for TrapCode {
105     type Err = ();
106 
107     fn from_str(s: &str) -> Result<Self, Self::Err> {
108         use self::TrapCode::*;
109         match s {
110             "stk_ovf" => Ok(StackOverflow),
111             "heap_oob" => Ok(HeapOutOfBounds),
112             "heap_misaligned" => Ok(HeapMisaligned),
113             "table_oob" => Ok(TableOutOfBounds),
114             "icall_null" => Ok(IndirectCallToNull),
115             "bad_sig" => Ok(BadSignature),
116             "int_ovf" => Ok(IntegerOverflow),
117             "int_divz" => Ok(IntegerDivisionByZero),
118             "bad_toint" => Ok(BadConversionToInteger),
119             "unreachable" => Ok(UnreachableCodeReached),
120             "interrupt" => Ok(Interrupt),
121             "null_reference" => Ok(NullReference),
122             "null_i31ref" => Ok(NullI31Ref),
123             _ if s.starts_with("user") => s[4..].parse().map(User).map_err(|_| ()),
124             _ => Err(()),
125         }
126     }
127 }
128 
129 #[cfg(test)]
130 mod tests {
131     use super::*;
132     use alloc::string::ToString;
133 
134     #[test]
135     fn display() {
136         for r in TrapCode::non_user_traps() {
137             let tc = *r;
138             assert_eq!(tc.to_string().parse(), Ok(tc));
139         }
140         assert_eq!("bogus".parse::<TrapCode>(), Err(()));
141 
142         assert_eq!(TrapCode::User(17).to_string(), "user17");
143         assert_eq!("user22".parse(), Ok(TrapCode::User(22)));
144         assert_eq!("user".parse::<TrapCode>(), Err(()));
145         assert_eq!("user-1".parse::<TrapCode>(), Err(()));
146         assert_eq!("users".parse::<TrapCode>(), Err(()));
147     }
148 }
149