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     /// This trap is resumable.
50     Interrupt,
51 
52     /// A user-defined trap code.
53     User(u16),
54 
55     /// A null reference was encountered which was required to be non-null.
56     NullReference,
57 
58     /// A null `i31ref` was encountered which was required to be non-null.
59     NullI31Ref,
60 }
61 
62 impl TrapCode {
63     /// Returns a slice of all traps except `TrapCode::User` traps
64     pub const fn non_user_traps() -> &'static [TrapCode] {
65         &[
66             TrapCode::StackOverflow,
67             TrapCode::HeapOutOfBounds,
68             TrapCode::HeapMisaligned,
69             TrapCode::TableOutOfBounds,
70             TrapCode::IndirectCallToNull,
71             TrapCode::BadSignature,
72             TrapCode::IntegerOverflow,
73             TrapCode::IntegerDivisionByZero,
74             TrapCode::BadConversionToInteger,
75             TrapCode::UnreachableCodeReached,
76             TrapCode::Interrupt,
77             TrapCode::NullReference,
78         ]
79     }
80 }
81 
82 impl Display for TrapCode {
83     fn fmt(&self, f: &mut Formatter) -> fmt::Result {
84         use self::TrapCode::*;
85         let identifier = match *self {
86             StackOverflow => "stk_ovf",
87             HeapOutOfBounds => "heap_oob",
88             HeapMisaligned => "heap_misaligned",
89             TableOutOfBounds => "table_oob",
90             IndirectCallToNull => "icall_null",
91             BadSignature => "bad_sig",
92             IntegerOverflow => "int_ovf",
93             IntegerDivisionByZero => "int_divz",
94             BadConversionToInteger => "bad_toint",
95             UnreachableCodeReached => "unreachable",
96             Interrupt => "interrupt",
97             User(x) => return write!(f, "user{}", x),
98             NullReference => "null_reference",
99             NullI31Ref => "null_i31ref",
100         };
101         f.write_str(identifier)
102     }
103 }
104 
105 impl FromStr for TrapCode {
106     type Err = ();
107 
108     fn from_str(s: &str) -> Result<Self, Self::Err> {
109         use self::TrapCode::*;
110         match s {
111             "stk_ovf" => Ok(StackOverflow),
112             "heap_oob" => Ok(HeapOutOfBounds),
113             "heap_misaligned" => Ok(HeapMisaligned),
114             "table_oob" => Ok(TableOutOfBounds),
115             "icall_null" => Ok(IndirectCallToNull),
116             "bad_sig" => Ok(BadSignature),
117             "int_ovf" => Ok(IntegerOverflow),
118             "int_divz" => Ok(IntegerDivisionByZero),
119             "bad_toint" => Ok(BadConversionToInteger),
120             "unreachable" => Ok(UnreachableCodeReached),
121             "interrupt" => Ok(Interrupt),
122             "null_reference" => Ok(NullReference),
123             "null_i31ref" => Ok(NullI31Ref),
124             _ if s.starts_with("user") => s[4..].parse().map(User).map_err(|_| ()),
125             _ => Err(()),
126         }
127     }
128 }
129 
130 #[cfg(test)]
131 mod tests {
132     use super::*;
133     use alloc::string::ToString;
134 
135     #[test]
136     fn display() {
137         for r in TrapCode::non_user_traps() {
138             let tc = *r;
139             assert_eq!(tc.to_string().parse(), Ok(tc));
140         }
141         assert_eq!("bogus".parse::<TrapCode>(), Err(()));
142 
143         assert_eq!(TrapCode::User(17).to_string(), "user17");
144         assert_eq!("user22".parse(), Ok(TrapCode::User(22)));
145         assert_eq!("user".parse::<TrapCode>(), Err(()));
146         assert_eq!("user-1".parse::<TrapCode>(), Err(()));
147         assert_eq!("users".parse::<TrapCode>(), Err(()));
148     }
149 }
150