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Merged
casey merged 3 commits into from
Feb 1, 2026
+72 −19
Merged

Use compact fingerprint serialization #233

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befb81e
Reform
casey Feb 1, 2026
3443811
Modify
casey Feb 1, 2026
b12ab9b
Amend
casey Feb 1, 2026
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10 changes: 7 additions & 3 deletions src/directory.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -58,9 +58,13 @@ impl Directory {
pub(crate) fn fingerprint(&self) -> Hash {
let mut hasher = FingerprintHasher::new(FingerprintPrefix::Directory);

for (component, entry) in &self.entries {
hasher.field(0, entry.fingerprint(component).as_bytes());
}
let entries = self
.entries
.iter()
.flat_map(|(component, entry)| *entry.fingerprint(component).as_bytes())
.collect::<Vec<u8>>();

hasher.field(0, &entries);

hasher.finalize()
}
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71 changes: 60 additions & 11 deletions src/fingerprint_hasher.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,15 +2,15 @@ use super::*;

pub(crate) struct FingerprintHasher {
hasher: Hasher,
tag: u64,
next: u64,
}

impl FingerprintHasher {
pub(crate) fn field(&mut self, tag: u64, field: &[u8]) {
assert!(tag >= self.tag, "unexpected tag {tag}");
self.tag = tag;
self.hasher.update(&tag.to_le_bytes());
self.hasher.update(&field.len().into_u64().to_le_bytes());
assert!(tag == self.next, "unexpected tag {tag}");
self.next += 1;
self.varint(tag);
self.varint(field.len().into_u64());
self.hasher.update(field);
}

Expand All @@ -19,11 +19,26 @@ impl FingerprintHasher {
}

pub(crate) fn new(context: FingerprintPrefix) -> Self {
let mut hasher = Hasher::new();
let mut hasher = Self {
hasher: Hasher::new(),
next: 0,
};
let prefix = context.prefix();
hasher.update(&prefix.len().into_u64().to_le_bytes());
hasher.update(prefix.as_bytes());
Self { hasher, tag: 0 }
hasher.varint(prefix.len().into_u64());
hasher.hasher.update(prefix.as_bytes());
hasher
}

fn varint(&mut self, mut n: u64) {
loop {
let byte = (n & 0b0111_1111).try_into().unwrap();
n >>= 7;
if n == 0 {
self.hasher.update(&[byte]);
break;
}
self.hasher.update(&[byte | 0b1000_0000]);
}
}
}

Expand All @@ -50,10 +65,44 @@ mod tests {
}

#[test]
#[should_panic(expected = "unexpected tag 0")]
#[should_panic(expected = "unexpected tag 2")]
fn tag_order() {
let mut hasher = FingerprintHasher::new(FingerprintPrefix::File);
hasher.field(1, &[]);
hasher.field(0, &[]);
hasher.field(2, &[]);
}

#[test]
fn varint_encoding() {
#[track_caller]
fn case(len: usize, varint: &[u8]) {
let field = iter::repeat_n(0, len).collect::<Vec<u8>>();

let actual = {
let mut hasher = FingerprintHasher::new(FingerprintPrefix::File);
hasher.field(0, &field);
hasher.finalize()
};

let expected = {
let mut hasher = Hasher::new();
hasher.update(&[13]);
hasher.update("filepack:file".as_bytes());
hasher.update(&[0]);
hasher.update(varint);
hasher.update(&field);
hasher.finalize().into()
};

assert_eq!(actual, expected, "unexpected hash for length {len} field");
}

case(0, &[0]);
case(1, &[1]);
case(127, &[0x7F]);
case(128, &[0x80, 0x01]);
case(129, &[0x81, 0x01]);
case(16383, &[0xFF, 0x7F]);
case(16384, &[0x80, 0x80, 0x01]);
}
}
4 changes: 2 additions & 2 deletions src/test.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,8 +15,8 @@ pub(crate) const PUBLIC_KEY: &str =

pub(crate) const SIGNATURE: &str = concat!(
"signature1a67dndhhmae7p6fsfnj0z37zf78cde6mwqgtms0y87h8ldlvvflyq4uf5nw04lxs6dgzqf",
"h4rdhxffxdukfwf4hq39d7vn2fu4eqlxf3q5j9kf2jslrnmfptk2rsj85tnp4ttqwagu46kkw64uf3dg",
"ffz3juhjnh9us86m2xzugrgxhn87kcn6azkernfruce7qh4mhzfefycuqq7t9j5l"
"h4rdhxffxdukfwf4hq39d7vn2fu4eqlxf3qsvczv268s6lkxtsc0eufqc5xz3g99640gtpwadk349d8f",
"qkjgl3tkp2m95ujz9arxzwt74ggzd3f9vnc6skcns9kn6xnxuqz6v26yrgw3lv6u",
);

pub(crate) const WEAK_PUBLIC_KEY: &str =
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2 changes: 1 addition & 1 deletion tests/fingerprint.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -19,7 +19,7 @@ fn fingerprint() {
)
.success();

let fingerprint = "package1ase89zy0tuschqfzg6ltu87devt2kt8mkr76zsuzf65kkxa4ycg8q0kds50";
let fingerprint = "package1a6mpecnnzja3uzmdxruf87074wy778qra3yn25xuudzgjx49v3tsq9qx6vs";

let path = test.path();

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4 changes: 2 additions & 2 deletions tests/verify.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -663,7 +663,7 @@ fn verify_fingerprint() {
.args([
"verify",
"--fingerprint",
"package1ase89zy0tuschqfzg6ltu87devt2kt8mkr76zsuzf65kkxa4ycg8q0kds50",
"package1a6mpecnnzja3uzmdxruf87074wy778qra3yn25xuudzgjx49v3tsq9qx6vs",
])
.stderr("successfully verified 1 file totaling 0 bytes\n")
.success()
Expand All @@ -676,7 +676,7 @@ fn verify_fingerprint() {
"\
fingerprint mismatch: `.*filepack\\.json`
expected: package1a4uf5nw04lxs6dgzqfh4rdhxffxdukfwf4hq39d7vn2fu4eqlxf3ql7ykr3
actual: package1ase89zy0tuschqfzg6ltu87devt2kt8mkr76zsuzf65kkxa4ycg8q0kds50
actual: package1a6mpecnnzja3uzmdxruf87074wy778qra3yn25xuudzgjx49v3tsq9qx6vs
error: fingerprint mismatch\n",
)
.failure();
Expand Down