foundry_evm_core/
decode.rs

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1//! Various utilities to decode test results.
2
3use crate::abi::{console, Vm};
4use alloy_dyn_abi::JsonAbiExt;
5use alloy_json_abi::{Error, JsonAbi};
6use alloy_primitives::{hex, map::HashMap, Log, Selector};
7use alloy_sol_types::{
8    ContractError::Revert, RevertReason, RevertReason::ContractError, SolEventInterface,
9    SolInterface, SolValue,
10};
11use foundry_common::SELECTOR_LEN;
12use itertools::Itertools;
13use revm::interpreter::InstructionResult;
14use std::{fmt, sync::OnceLock};
15
16/// A skip reason.
17#[derive(Clone, Debug, PartialEq, Eq)]
18pub struct SkipReason(pub Option<String>);
19
20impl SkipReason {
21    /// Decodes a skip reason, if any.
22    pub fn decode(raw_result: &[u8]) -> Option<Self> {
23        raw_result.strip_prefix(crate::constants::MAGIC_SKIP).map(|reason| {
24            let reason = String::from_utf8_lossy(reason).into_owned();
25            Self((!reason.is_empty()).then_some(reason))
26        })
27    }
28
29    /// Decodes a skip reason from a string that was obtained by formatting `Self`.
30    ///
31    /// This is a hack to support re-decoding a skip reason in proptest.
32    pub fn decode_self(s: &str) -> Option<Self> {
33        s.strip_prefix("skipped").map(|rest| Self(rest.strip_prefix(": ").map(ToString::to_string)))
34    }
35}
36
37impl fmt::Display for SkipReason {
38    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
39        f.write_str("skipped")?;
40        if let Some(reason) = &self.0 {
41            f.write_str(": ")?;
42            f.write_str(reason)?;
43        }
44        Ok(())
45    }
46}
47
48/// Decode a set of logs, only returning logs from DSTest logging events and Hardhat's `console.log`
49pub fn decode_console_logs(logs: &[Log]) -> Vec<String> {
50    logs.iter().filter_map(decode_console_log).collect()
51}
52
53/// Decode a single log.
54///
55/// This function returns [None] if it is not a DSTest log or the result of a Hardhat
56/// `console.log`.
57pub fn decode_console_log(log: &Log) -> Option<String> {
58    console::ds::ConsoleEvents::decode_log(log, false).ok().map(|decoded| decoded.to_string())
59}
60
61/// Decodes revert data.
62#[derive(Clone, Debug, Default)]
63pub struct RevertDecoder {
64    /// The custom errors to use for decoding.
65    pub errors: HashMap<Selector, Vec<Error>>,
66}
67
68impl Default for &RevertDecoder {
69    fn default() -> Self {
70        static EMPTY: OnceLock<RevertDecoder> = OnceLock::new();
71        EMPTY.get_or_init(RevertDecoder::new)
72    }
73}
74
75impl RevertDecoder {
76    /// Creates a new, empty revert decoder.
77    pub fn new() -> Self {
78        Self::default()
79    }
80
81    /// Sets the ABIs to use for error decoding.
82    ///
83    /// Note that this is decently expensive as it will hash all errors for faster indexing.
84    pub fn with_abis<'a>(mut self, abi: impl IntoIterator<Item = &'a JsonAbi>) -> Self {
85        self.extend_from_abis(abi);
86        self
87    }
88
89    /// Sets the ABI to use for error decoding.
90    ///
91    /// Note that this is decently expensive as it will hash all errors for faster indexing.
92    pub fn with_abi(mut self, abi: &JsonAbi) -> Self {
93        self.extend_from_abi(abi);
94        self
95    }
96
97    /// Sets the ABI to use for error decoding, if it is present.
98    ///
99    /// Note that this is decently expensive as it will hash all errors for faster indexing.
100    pub fn with_abi_opt(mut self, abi: Option<&JsonAbi>) -> Self {
101        if let Some(abi) = abi {
102            self.extend_from_abi(abi);
103        }
104        self
105    }
106
107    /// Extends the decoder with the given ABI's custom errors.
108    pub fn extend_from_abis<'a>(&mut self, abi: impl IntoIterator<Item = &'a JsonAbi>) {
109        for abi in abi {
110            self.extend_from_abi(abi);
111        }
112    }
113
114    /// Extends the decoder with the given ABI's custom errors.
115    pub fn extend_from_abi(&mut self, abi: &JsonAbi) {
116        for error in abi.errors() {
117            self.push_error(error.clone());
118        }
119    }
120
121    /// Adds a custom error to use for decoding.
122    pub fn push_error(&mut self, error: Error) {
123        self.errors.entry(error.selector()).or_default().push(error);
124    }
125
126    /// Tries to decode an error message from the given revert bytes.
127    ///
128    /// Note that this is just a best-effort guess, and should not be relied upon for anything other
129    /// than user output.
130    pub fn decode(&self, err: &[u8], status: Option<InstructionResult>) -> String {
131        self.maybe_decode(err, status).unwrap_or_else(|| {
132            if err.is_empty() {
133                "<empty revert data>".to_string()
134            } else {
135                trimmed_hex(err)
136            }
137        })
138    }
139
140    /// Tries to decode an error message from the given revert bytes.
141    ///
142    /// See [`decode`](Self::decode) for more information.
143    pub fn maybe_decode(&self, err: &[u8], status: Option<InstructionResult>) -> Option<String> {
144        if let Some(reason) = SkipReason::decode(err) {
145            return Some(reason.to_string());
146        }
147
148        // Solidity's `Error(string)` (handled separately in order to strip revert: prefix)
149        if let Some(ContractError(Revert(revert))) = RevertReason::decode(err) {
150            return Some(revert.reason);
151        }
152
153        // Solidity's `Panic(uint256)` and `Vm`'s custom errors.
154        if let Ok(e) = alloy_sol_types::ContractError::<Vm::VmErrors>::abi_decode(err, false) {
155            return Some(e.to_string());
156        }
157
158        let string_decoded = decode_as_non_empty_string(err);
159
160        if let Some((selector, data)) = err.split_first_chunk::<SELECTOR_LEN>() {
161            // Custom errors.
162            if let Some(errors) = self.errors.get(selector) {
163                for error in errors {
164                    // If we don't decode, don't return an error, try to decode as a string
165                    // later.
166                    if let Ok(decoded) = error.abi_decode_input(data, false) {
167                        return Some(format!(
168                            "{}({})",
169                            error.name,
170                            decoded.iter().map(foundry_common::fmt::format_token).format(", ")
171                        ));
172                    }
173                }
174            }
175
176            if string_decoded.is_some() {
177                return string_decoded
178            }
179
180            // Generic custom error.
181            return Some({
182                let mut s = format!("custom error {}", hex::encode_prefixed(selector));
183                if !data.is_empty() {
184                    s.push_str(": ");
185                    match std::str::from_utf8(data) {
186                        Ok(data) => s.push_str(data),
187                        Err(_) => s.push_str(&hex::encode(data)),
188                    }
189                }
190                s
191            })
192        }
193
194        if string_decoded.is_some() {
195            return string_decoded
196        }
197
198        if let Some(status) = status {
199            if !status.is_ok() {
200                return Some(format!("EvmError: {status:?}"));
201            }
202        }
203        if err.is_empty() {
204            None
205        } else {
206            Some(format!("custom error bytes {}", hex::encode_prefixed(err)))
207        }
208    }
209}
210
211/// Helper function that decodes provided error as an ABI encoded or an ASCII string (if not empty).
212fn decode_as_non_empty_string(err: &[u8]) -> Option<String> {
213    // ABI-encoded `string`.
214    if let Ok(s) = String::abi_decode(err, true) {
215        if !s.is_empty() {
216            return Some(s);
217        }
218    }
219
220    // ASCII string.
221    if err.is_ascii() {
222        let msg = std::str::from_utf8(err).unwrap().to_string();
223        if !msg.is_empty() {
224            return Some(msg);
225        }
226    }
227
228    None
229}
230
231fn trimmed_hex(s: &[u8]) -> String {
232    let n = 32;
233    if s.len() <= n {
234        hex::encode(s)
235    } else {
236        format!(
237            "{}…{} ({} bytes)",
238            &hex::encode(&s[..n / 2]),
239            &hex::encode(&s[s.len() - n / 2..]),
240            s.len(),
241        )
242    }
243}
244
245#[cfg(test)]
246mod tests {
247    use super::*;
248    #[test]
249    fn test_trimmed_hex() {
250        assert_eq!(trimmed_hex(&hex::decode("1234567890").unwrap()), "1234567890");
251        assert_eq!(
252            trimmed_hex(&hex::decode("492077697368207275737420737570706F72746564206869676865722D6B696E646564207479706573").unwrap()),
253            "49207769736820727573742073757070…6865722d6b696e646564207479706573 (41 bytes)"
254        );
255    }
256}
foundry_evm_core/decode.rs

foundry_evm_core/
decode.rs
