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
145
146
147
148
149
150
151
152
153
154
155
156

use std::fmt::Debug;
use thiserror::Error;

use super::region_validation_error::RegionValidationError;
use crate::memory::Region;

/// An error in the communcation between contract and host. Those happen around imports and exports.
#[derive(Error, Debug)]
#[non_exhaustive]
pub enum CommunicationError {
    #[error(
        "The Wasm memory address {} provided by the contract could not be dereferenced: {}",
        offset,
        msg
    )]
    DerefErr {
        /// the position in a Wasm linear memory
        offset: u32,
        msg: String,
    },
    #[error("Got an invalid value for iteration order: {}", value)]
    InvalidOrder { value: i32 },
    #[error("Got an invalid region: {}", source)]
    InvalidRegion {
        #[from]
        source: RegionValidationError,
    },
    /// Whenever UTF-8 bytes cannot be decoded into a unicode string, e.g. in String::from_utf8 or str::from_utf8.
    #[error("Cannot decode UTF8 bytes into string: {}", msg)]
    InvalidUtf8 { msg: String },
    #[error("Region length too big. Got {}, limit {}", length, max_length)]
    // Note: this only checks length, not capacity
    RegionLengthTooBig { length: usize, max_length: usize },
    #[error("Region too small. Got {}, required {}", size, required)]
    RegionTooSmall { size: usize, required: usize },
    #[error("Tried to access memory of region {:?} in Wasm memory of size {} bytes. This typically happens when the given Region pointer does not point to a proper Region struct.", region, memory_size)]
    RegionAccessErr {
        region: Region,
        /// Current size of the linear memory in bytes
        memory_size: usize,
    },
    #[error("Got a zero Wasm address")]
    ZeroAddress {},
}

impl CommunicationError {
    pub(crate) fn deref_err(offset: u32, msg: impl Into<String>) -> Self {
        CommunicationError::DerefErr {
            offset,
            msg: msg.into(),
        }
    }

    #[allow(dead_code)]
    pub(crate) fn invalid_order(value: i32) -> Self {
        CommunicationError::InvalidOrder { value }
    }

    #[allow(dead_code)]
    pub(crate) fn invalid_utf8(msg: impl ToString) -> Self {
        CommunicationError::InvalidUtf8 {
            msg: msg.to_string(),
        }
    }

    pub(crate) fn region_length_too_big(length: usize, max_length: usize) -> Self {
        CommunicationError::RegionLengthTooBig { length, max_length }
    }

    pub(crate) fn region_too_small(size: usize, required: usize) -> Self {
        CommunicationError::RegionTooSmall { size, required }
    }

    pub(crate) fn region_access_err(region: Region, memory_size: usize) -> Self {
        CommunicationError::RegionAccessErr {
            region,
            memory_size,
        }
    }

    pub(crate) fn zero_address() -> Self {
        CommunicationError::ZeroAddress {}
    }
}

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

    // constructors

    #[test]
    fn deref_err() {
        let error = CommunicationError::deref_err(345, "broken stuff");
        match error {
            CommunicationError::DerefErr { offset, msg, .. } => {
                assert_eq!(offset, 345);
                assert_eq!(msg, "broken stuff");
            }
            e => panic!("Unexpected error: {e:?}"),
        }
    }

    #[test]
    fn invalid_order() {
        let error = CommunicationError::invalid_order(-745);
        match error {
            CommunicationError::InvalidOrder { value, .. } => assert_eq!(value, -745),
            e => panic!("Unexpected error: {e:?}"),
        }
    }

    #[test]
    fn invalid_utf8() {
        let error = CommunicationError::invalid_utf8("broken");
        match error {
            CommunicationError::InvalidUtf8 { msg, .. } => assert_eq!(msg, "broken"),
            e => panic!("Unexpected error: {e:?}"),
        }
    }

    #[test]
    fn region_length_too_big_works() {
        let error = CommunicationError::region_length_too_big(50, 20);
        match error {
            CommunicationError::RegionLengthTooBig {
                length, max_length, ..
            } => {
                assert_eq!(length, 50);
                assert_eq!(max_length, 20);
            }
            e => panic!("Unexpected error: {e:?}"),
        }
    }

    #[test]
    fn region_too_small_works() {
        let error = CommunicationError::region_too_small(12, 33);
        match error {
            CommunicationError::RegionTooSmall { size, required, .. } => {
                assert_eq!(size, 12);
                assert_eq!(required, 33);
            }
            e => panic!("Unexpected error: {e:?}"),
        }
    }

    #[test]
    fn zero_address() {
        let error = CommunicationError::zero_address();
        match error {
            CommunicationError::ZeroAddress { .. } => {}
            e => panic!("Unexpected error: {e:?}"),
        }
    }
}