feat(tvix/store): add nixpath
This implements the NixPath structure. NixPath allow to parse a string to a nix path. If the parsing fails, a DecodeError will be raised. Change-Id: I28363cdcfb27f04bf21a11c0d130b461667e3720 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7706 Tested-by: BuildkiteCI Reviewed-by: tazjin <tazjin@tvl.su>
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mod nixbase32;
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mod nixpath;
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mod proto;
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#[cfg(test)]
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142
tvix/store/src/nixpath.rs
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142
tvix/store/src/nixpath.rs
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use crate::nixbase32::NIXBASE32;
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use data_encoding::DecodeError;
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use std::fmt;
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use thiserror::Error;
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const PATH_HASH_SIZE: usize = 20;
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/// Errors that can occur during the validation of name characters.
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#[derive(Debug, PartialEq, Eq, Error)]
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pub enum ParseNixPathError {
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#[error("Dash is missing")]
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MissingDash(),
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#[error("Hash encoding is invalid {0}")]
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InvalidHashEncoding(DecodeError),
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#[error("Invalid name {0}")]
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InvalidName(String),
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}
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#[derive(Debug, PartialEq, Eq)]
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pub struct NixPath {
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digest: [u8; PATH_HASH_SIZE],
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name: String,
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}
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impl NixPath {
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pub fn from_string(s: &str) -> Result<NixPath, ParseNixPathError> {
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let encoded_path_hash_size = NIXBASE32.encode_len(PATH_HASH_SIZE);
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let name_offset = encoded_path_hash_size + 1;
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// the whole string needs to be at least:
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//
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// - 32 characters (encoded hash)
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// - 1 dash
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// - 1 character for the name
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if s.len() < name_offset + 1 {
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return Err(ParseNixPathError::InvalidName("".to_string()));
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}
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let digest = match NIXBASE32.decode(s[..encoded_path_hash_size].as_bytes()) {
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Ok(decoded) => decoded,
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Err(decoder_error) => {
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return Err(ParseNixPathError::InvalidHashEncoding(decoder_error))
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}
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};
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if s.as_bytes()[encoded_path_hash_size] != b'-' {
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return Err(ParseNixPathError::MissingDash());
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}
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NixPath::validate_characters(&s[name_offset..])?;
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// copy the digest:Vec<u8> to a [u8; PATH_HASH_SIZE]
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let mut buffer: [u8; PATH_HASH_SIZE] = [0; PATH_HASH_SIZE];
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buffer[..PATH_HASH_SIZE].copy_from_slice(&digest[..PATH_HASH_SIZE]);
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Ok(NixPath {
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name: s[name_offset..].to_string(),
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digest: buffer,
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})
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}
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fn validate_characters(s: &str) -> Result<(), ParseNixPathError> {
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for c in s.chars() {
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if c.is_ascii_alphanumeric()
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|| c == '-'
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|| c == '_'
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|| c == '.'
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|| c == '+'
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|| c == '?'
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|| c == '='
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{
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continue;
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}
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return Err(ParseNixPathError::InvalidName(s.to_string()));
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}
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Ok(())
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}
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}
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impl fmt::Display for NixPath {
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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write!(
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f,
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"{}-{}",
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crate::nixbase32::NIXBASE32.encode(&self.digest),
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self.name
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)
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}
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}
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#[cfg(test)]
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mod tests {
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use crate::nixpath::PATH_HASH_SIZE;
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use super::NixPath;
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#[test]
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fn happy_path() {
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let example_nix_path_str =
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"00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432";
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let nixpath =
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NixPath::from_string(&example_nix_path_str).expect("Error parsing example string");
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let expected_digest: [u8; PATH_HASH_SIZE] = [
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0x8a, 0x12, 0x32, 0x15, 0x22, 0xfd, 0x91, 0xef, 0xbd, 0x60, 0xeb, 0xb2, 0x48, 0x1a,
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0xf8, 0x85, 0x80, 0xf6, 0x16, 0x00,
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];
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assert_eq!("net-tools-1.60_p20170221182432", nixpath.name);
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assert_eq!(nixpath.digest, expected_digest);
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assert_eq!(example_nix_path_str, nixpath.to_string())
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}
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#[test]
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fn invalid_hash_length() {
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NixPath::from_string("00bgd045z0d4icpbc2yy-net-tools-1.60_p20170221182432")
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.expect_err("No error raised.");
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}
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#[test]
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fn invalid_encoding_hash() {
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NixPath::from_string("00bgd045z0d4icpbc2yyz4gx48aku4la-net-tools-1.60_p20170221182432")
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.expect_err("No error raised.");
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}
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#[test]
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fn more_than_just_the_bare_nix_store_path() {
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NixPath::from_string(
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"00bgd045z0d4icpbc2yyz4gx48aku4la-net-tools-1.60_p20170221182432/bin/arp",
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)
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.expect_err("No error raised.");
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}
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#[test]
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fn no_dash_between_hash_and_name() {
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NixPath::from_string("00bgd045z0d4icpbc2yyz4gx48ak44lanet-tools-1.60_p20170221182432")
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.expect_err("No error raised.");
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}
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}
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