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minor optimization to 'to_canonical_json'

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* don't clone hash keys, just use references
* we don't need a String, stick to Vec<u8> and use
  serde_json::to_writer to avoid a temporary strings
  altogether

Signed-off-by: Wolfgang Bumiller <w.bumiller@proxmox.com>
This commit is contained in:
Wolfgang Bumiller 2020-07-09 12:08:00 +02:00
parent 2774566b03
commit 20a4e4e252
1 changed files with 34 additions and 27 deletions
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61
src/backup/manifest.rs
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@ -130,39 +130,47 @@ impl BackupManifest {
}
// Generate cannonical json
fn to_canonical_json(value: &Value, output: &mut String) -> Result<(), Error> {
fn to_canonical_json(value: &Value) -> Result<Vec<u8>, Error> {
let mut data = Vec::new();
Self::write_canonical_json(value, &mut data)?;
Ok(data)
}
fn write_canonical_json(value: &Value, output: &mut Vec<u8>) -> Result<(), Error> {
match value {
Value::Null => bail!("got unexpected null value"),
Value::String(_) => {
output.push_str(&serde_json::to_string(value)?);
},
Value::Number(_) => {
output.push_str(&serde_json::to_string(value)?);
Value::String(_) | Value::Number(_) | Value::Bool(_) => {
serde_json::to_writer(output, &value)?;
}
Value::Bool(_) => {
output.push_str(&serde_json::to_string(value)?);
},
Value::Array(list) => {
output.push('[');
for (i, item) in list.iter().enumerate() {
if i != 0 { output.push(','); }
Self::to_canonical_json(item, output)?;
output.push(b'[');
let mut iter = list.iter();
if let Some(item) = iter.next() {
Self::write_canonical_json(item, output)?;
for item in iter {
output.push(b',');
Self::write_canonical_json(item, output)?;
}
}
output.push(']');
output.push(b']');
}
Value::Object(map) => {
output.push('{');
let mut keys: Vec<String> = map.keys().map(|s| s.clone()).collect();
output.push(b'{');
let mut keys: Vec<&str> = map.keys().map(String::as_str).collect();
keys.sort();
for (i, key) in keys.iter().enumerate() {
let item = map.get(key).unwrap();
if i != 0 { output.push(','); }
output.push_str(&serde_json::to_string(&Value::String(key.clone()))?);
output.push(':');
Self::to_canonical_json(item, output)?;
let mut iter = keys.into_iter();
if let Some(key) = iter.next() {
output.extend(key.as_bytes());
output.push(b':');
Self::write_canonical_json(&map[key], output)?;
for key in iter {
output.push(b',');
output.extend(key.as_bytes());
output.push(b':');
Self::write_canonical_json(&map[key], output)?;
}
}
output.push('}');
output.push(b'}');
}
}
Ok(())
@ -182,10 +190,9 @@ impl BackupManifest {
signed_data.as_object_mut().unwrap().remove("unprotected"); // exclude
let mut canonical = String::new();
Self::to_canonical_json(&signed_data, &mut canonical)?;
let canonical = Self::to_canonical_json(&signed_data)?;
let sig = crypt_config.compute_auth_tag(canonical.as_bytes());
let sig = crypt_config.compute_auth_tag(&canonical);
Ok(sig)
}