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use crate::nix_hash;
use crate::output::Output;
use crate::write;
use serde::{Deserialize, Serialize};
use sha2::{Digest, Sha256};
use std::{collections::BTreeMap, fmt, fmt::Write, iter::FromIterator};
use tvix_store::nixbase32::NIXBASE32;
use tvix_store::nixpath::STORE_DIR;
#[derive(Serialize, Deserialize)]
pub struct Derivation {
outputs: BTreeMap<String, Output>,
input_sources: Vec<String>,
input_derivations: BTreeMap<String, Vec<String>>,
platform: String,
builder: String,
arguments: Vec<String>,
environment: BTreeMap<String, String>,
}
impl Derivation {
pub fn serialize(&self, writer: &mut impl Write) -> Result<(), fmt::Error> {
writer.write_str(write::DERIVATION_PREFIX)?;
writer.write_char(write::PAREN_OPEN)?;
write::write_outputs(writer, &self.outputs)?;
write::write_input_derivations(writer, &self.input_derivations)?;
write::write_input_sources(writer, &self.input_sources)?;
write::write_platfrom(writer, &self.platform)?;
write::write_builder(writer, &self.builder)?;
write::write_arguments(writer, &self.arguments)?;
write::write_enviroment(writer, &self.environment)?;
writer.write_char(write::PAREN_CLOSE)?;
Ok(())
}
/// Returns the path of a Derivation struct.
///
/// The path is calculated like this:
/// - Write the fingerprint of the Derivation to the sha256 hash function.
/// This is: `text:`,
/// all d.InputDerivations and d.InputSources (sorted, separated by a `:`),
/// a `:`,
/// a `sha256:`, followed by the sha256 digest of the ATerm representation (hex-encoded)
/// a `:`,
/// the storeDir, followed by a `:`,
/// the name of a derivation,
/// a `.drv`.
/// - Write the .drv A-Term contents to a hash function
/// - Take the digest, run hash.CompressHash(digest, 20) on it.
/// - Encode it with nixbase32
/// - Construct the full path $storeDir/$nixbase32EncodedCompressedHash-$name.drv
pub fn calculate_derivation_path(&self, name: &str) -> String {
let mut hasher = Sha256::new();
// collect the list of paths from input_sources and input_derivations
// into a sorted list, and join them by :
hasher.update(write::TEXT_COLON);
let concat_inputs: Vec<String> = {
let mut inputs = self.input_sources.clone();
let input_derivation_keys: Vec<String> =
self.input_derivations.keys().cloned().collect();
inputs.extend(input_derivation_keys);
inputs.sort();
inputs
};
for input in concat_inputs {
hasher.update(input);
hasher.update(write::COLON);
}
// calculate the sha256 hash of the ATerm representation, and represent
// it as a hex-encoded string (prefixed with sha256:).
hasher.update(write::SHA256_COLON);
let digest = {
let mut derivation_hasher = Sha256::new();
derivation_hasher.update(self.to_string());
derivation_hasher.finalize()
};
hasher.update(format!("{:x}", digest));
hasher.update(write::COLON);
hasher.update(STORE_DIR);
hasher.update(write::COLON);
hasher.update(name);
hasher.update(write::DOT_FILE_EXT);
let compressed = {
let aterm_digest = Vec::from_iter(hasher.finalize());
nix_hash::compress_hash(&aterm_digest, 20)
};
format!(
"{}-{}{}",
NIXBASE32.encode(&compressed),
name,
write::DOT_FILE_EXT
)
}
}
impl fmt::Display for Derivation {
/// Formats the Derivation in ATerm representation.
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
self.serialize(f)
}
}
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