wasmer_cache/
hash.rs

1use crate::DeserializeError;
2use std::string::ToString;
3use std::{
4    fmt::{self, Display, Formatter},
5    str::FromStr,
6};
7
8/// A hash used as a key when loading and storing modules in a
9/// [`crate::Cache`].
10#[derive(Debug, Copy, Clone, PartialEq, Eq, Hash)]
11// Hash is made up of a 32 byte array
12pub struct Hash([u8; 32]);
13
14impl Hash {
15    /// Creates a new instance from 32 raw bytes.
16    /// Does not perform any hashing. In order to create a hash from data,
17    /// use [`Hash::generate()`].
18    pub fn new(bytes: [u8; 32]) -> Self {
19        Self(bytes)
20    }
21
22    /// Creates a new hash from a slice of bytes.
23    pub fn generate(bytes: &[u8]) -> Self {
24        let hash = blake3::hash(bytes);
25        Self::new(hash.into())
26    }
27}
28
29impl Display for Hash {
30    /// Print the hexadecimal representation of the
31    /// stored hash.
32    fn fmt(&self, f: &mut Formatter<'_>) -> fmt::Result {
33        let mut buffer = [0_u8; 64];
34
35        hex::encode_to_slice(self.0, &mut buffer)
36            .expect("Can never fail with a hard-coded buffer length");
37        let s = std::str::from_utf8(&buffer).map_err(|_| fmt::Error)?;
38
39        f.write_str(s)
40    }
41}
42
43impl FromStr for Hash {
44    type Err = DeserializeError;
45    /// Create hash from hexadecimal representation
46    fn from_str(s: &str) -> Result<Self, Self::Err> {
47        let bytes = hex::decode(s).map_err(|e| {
48            DeserializeError::Generic(format!(
49                "Could not decode prehashed key as hexadecimal: {}",
50                e
51            ))
52        })?;
53        if bytes.len() != 32 {
54            return Err(DeserializeError::Generic(
55                "Prehashed keys must deserialze into exactly 32 bytes".to_string(),
56            ));
57        }
58        Ok(Self(bytes[0..32].try_into().map_err(|e| {
59            DeserializeError::Generic(format!("Could not get first 32 bytes: {}", e))
60        })?))
61    }
62}
63
64#[cfg(test)]
65mod tests {
66    use super::*;
67
68    #[test]
69    fn hash_is_displayed_as_hex() {
70        let original = [
71            0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF, 0x12, 0x65, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF,
72            0x12, 0x65, 0xAA, 0xBB, 0xCC, 0xDD, 0xEE, 0xFF, 0x12, 0x65, 0xAA, 0xBB, 0xCC, 0xDD,
73            0xEE, 0xFF, 0x12, 0x65,
74        ];
75        let hash = Hash::new(original);
76        assert_eq!(
77            hash.to_string(),
78            "aabbccddeeff1265aabbccddeeff1265aabbccddeeff1265aabbccddeeff1265"
79        );
80    }
81}
wasmer_cache/hash.rs

wasmer_cache/
hash.rs
