7f7c1ae7be
Change-Id: I62cbe883afcf3dd0c8d4de0e3b845069eb750c97 Reviewed-on: https://cl.tvl.fyi/c/depot/+/9855 Reviewed-by: flokli <flokli@flokli.de> Tested-by: BuildkiteCI
355 lines
12 KiB
Rust
355 lines
12 KiB
Rust
use crate::nixbase32::{self, Nixbase32DecodeError};
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use data_encoding::BASE64;
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use std::{fmt, path::PathBuf, str::FromStr};
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use thiserror;
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#[cfg(target_family = "unix")]
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use std::os::unix::ffi::OsStringExt;
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mod utils;
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pub use utils::*;
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pub const DIGEST_SIZE: usize = 20;
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// lazy_static doesn't allow us to call NIXBASE32.encode_len(), so we ran it
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// manually and have an assert in the tests.
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pub const ENCODED_DIGEST_SIZE: usize = 32;
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// The store dir prefix, without trailing slash.
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// That's usually where the Nix store is mounted at.
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pub const STORE_DIR: &str = "/nix/store";
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pub const STORE_DIR_WITH_SLASH: &str = "/nix/store/";
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/// Errors that can occur when parsing a literal store path
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#[derive(Debug, PartialEq, Eq, thiserror::Error)]
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pub enum Error {
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#[error("Dash is missing between hash and name")]
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MissingDash(),
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#[error("Hash encoding is invalid: {0}")]
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InvalidHashEncoding(Nixbase32DecodeError),
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#[error("Invalid length")]
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InvalidLength(),
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#[error(
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"Invalid name: \"{}\", character at position {} is invalid",
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std::str::from_utf8(.0).unwrap_or(&BASE64.encode(.0)),
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.1,
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)]
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InvalidName(Vec<u8>, usize),
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#[error("Tried to parse an absolute path which was missing the store dir prefix.")]
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MissingStoreDir(),
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}
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/// Represents a path in the Nix store (a direct child of [STORE_DIR]).
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///
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/// It consists of a digest (20 bytes), and a name, which is a string.
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/// The name may only contain ASCII alphanumeric, or one of the following
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/// characters: `-`, `_`, `.`, `+`, `?`, `=`.
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/// The name is usually used to describe the pname and version of a package.
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/// Derivation paths can also be represented as store paths, their names just
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/// end with the `.drv` prefix.
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///
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/// A [StorePath] does not encode any additional subpath "inside" the store
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/// path.
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#[derive(Clone, Debug, PartialEq, Eq, Hash)]
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pub struct StorePath {
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digest: [u8; DIGEST_SIZE],
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name: String,
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}
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impl StorePath {
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pub fn digest(&self) -> &[u8; DIGEST_SIZE] {
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&self.digest
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}
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pub fn name(&self) -> &str {
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self.name.as_ref()
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}
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}
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impl PartialOrd for StorePath {
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fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
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self.digest.partial_cmp(&other.digest)
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}
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}
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impl Ord for StorePath {
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fn cmp(&self, other: &Self) -> std::cmp::Ordering {
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self.digest.cmp(&other.digest)
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}
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}
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impl FromStr for StorePath {
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type Err = Error;
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/// Construct a [StorePath] by passing the `$digest-$name` string
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/// that comes after [STORE_DIR_WITH_SLASH].
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fn from_str(s: &str) -> Result<Self, Self::Err> {
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Self::from_bytes(s.as_bytes())
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}
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}
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impl StorePath {
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/// Construct a [StorePath] by passing the `$digest-$name` string
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/// that comes after [STORE_DIR_WITH_SLASH].
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pub fn from_bytes(s: &[u8]) -> Result<StorePath, Error> {
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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() < ENCODED_DIGEST_SIZE + 2 {
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Err(Error::InvalidLength())?
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}
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let digest = match nixbase32::decode(&s[..ENCODED_DIGEST_SIZE]) {
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Ok(decoded) => decoded,
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Err(decoder_error) => return Err(Error::InvalidHashEncoding(decoder_error)),
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};
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if s[ENCODED_DIGEST_SIZE] != b'-' {
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return Err(Error::MissingDash());
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}
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Ok(StorePath {
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name: validate_name(&s[ENCODED_DIGEST_SIZE + 1..])?,
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digest: digest.try_into().expect("size is known"),
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})
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}
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/// Construct a [StorePath] from an absolute store path string.
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/// This is equivalent to calling [StorePath::from_bytes], but stripping the
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/// [STORE_DIR_WITH_SLASH] prefix before.
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pub fn from_absolute_path(s: &[u8]) -> Result<StorePath, Error> {
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match s.strip_prefix(STORE_DIR_WITH_SLASH.as_bytes()) {
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Some(s_stripped) => Self::from_bytes(s_stripped),
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None => Err(Error::MissingStoreDir()),
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}
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}
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/// Construct a [StorePath] from a name and digest.
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pub fn from_name_and_digest(name: String, digest: &[u8]) -> Result<StorePath, Error> {
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Ok(Self {
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name: validate_name(name.as_bytes())?,
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digest: digest.try_into().map_err(|_| Error::InvalidLength())?,
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})
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}
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/// Decompose a string into a [StorePath] and a [PathBuf] containing the
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/// rest of the path, or an error.
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#[cfg(target_family = "unix")]
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pub fn from_absolute_path_full(s: &str) -> Result<(StorePath, PathBuf), Error> {
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// strip [STORE_DIR_WITH_SLASH] from s
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match s.strip_prefix(STORE_DIR_WITH_SLASH) {
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None => Err(Error::MissingStoreDir()),
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Some(rest) => {
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// put rest in a PathBuf
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let mut p = PathBuf::new();
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p.push(rest);
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let mut it = p.components();
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// The first component of the rest must be parse-able as a [StorePath]
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if let Some(first_component) = it.next() {
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// convert first component to StorePath
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let first_component_bytes = first_component.as_os_str().to_owned().into_vec();
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let store_path = StorePath::from_bytes(&first_component_bytes)?;
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// collect rest
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let rest_buf: PathBuf = it.collect();
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Ok((store_path, rest_buf))
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} else {
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Err(Error::InvalidLength()) // Well, or missing "/"?
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}
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}
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}
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}
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/// Converts the [StorePath] to an absolute store path string.
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/// That is just the string representation, prefixed with the store prefix
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/// ([STORE_DIR_WITH_SLASH]),
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pub fn to_absolute_path(&self) -> String {
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format!("{}{}", STORE_DIR_WITH_SLASH, self)
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}
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}
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/// Checks a given &[u8] to match the restrictions for [StorePath::name], and
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/// returns the name as string if successful.
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pub(crate) fn validate_name(s: &[u8]) -> Result<String, Error> {
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// Empty or excessively long names are not allowed.
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if s.is_empty() || s.len() > 211 {
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return Err(Error::InvalidLength());
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}
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for (i, c) in s.iter().enumerate() {
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if c.is_ascii_alphanumeric()
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|| (*c == b'.' && i != 0) // can't start with a dot
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|| *c == b'-'
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|| *c == b'_'
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|| *c == b'+'
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|| *c == b'?'
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|| *c == b'='
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{
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continue;
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}
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return Err(Error::InvalidName(s.to_vec(), i));
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}
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Ok(String::from_utf8(s.to_vec()).unwrap())
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}
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impl fmt::Display for StorePath {
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/// The string representation of a store path starts with a digest (20
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/// bytes), [crate::nixbase32]-encoded, followed by a `-`,
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/// and ends with the name.
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fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
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write!(f, "{}-{}", nixbase32::encode(&self.digest), self.name)
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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 std::path::PathBuf;
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use crate::nixbase32;
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use crate::store_path::{DIGEST_SIZE, ENCODED_DIGEST_SIZE};
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use hex_literal::hex;
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use test_case::test_case;
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use super::{Error, StorePath};
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#[test]
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fn encoded_digest_size() {
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assert_eq!(ENCODED_DIGEST_SIZE, nixbase32::encode_len(DIGEST_SIZE));
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}
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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 = StorePath::from_bytes(example_nix_path_str.as_bytes())
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.expect("Error parsing example string");
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let expected_digest: [u8; DIGEST_SIZE] = hex!("8a12321522fd91efbd60ebb2481af88580f61600");
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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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/// This is the store path rejected when `nix-store --add`'ing an
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/// empty `.gitignore` file.
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///
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/// Nix 2.4 accidentally dropped this behaviour, but this is considered a bug.
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/// See https://github.com/NixOS/nix/pull/9095.
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#[test]
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fn starts_with_dot() {
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StorePath::from_bytes(b"fli4bwscgna7lpm7v5xgnjxrxh0yc7ra-.gitignore")
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.expect_err("must fail");
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}
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#[test]
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fn empty_name() {
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StorePath::from_bytes(b"00bgd045z0d4icpbc2yy-").expect_err("must fail");
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}
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#[test]
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fn excessive_length() {
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StorePath::from_bytes(b"00bgd045z0d4icpbc2yy-aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa")
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.expect_err("must fail");
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}
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#[test]
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fn invalid_hash_length() {
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StorePath::from_bytes(b"00bgd045z0d4icpbc2yy-net-tools-1.60_p20170221182432")
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.expect_err("must fail");
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}
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#[test]
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fn invalid_encoding_hash() {
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StorePath::from_bytes(b"00bgd045z0d4icpbc2yyz4gx48aku4la-net-tools-1.60_p20170221182432")
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.expect_err("must fail");
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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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StorePath::from_bytes(
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b"00bgd045z0d4icpbc2yyz4gx48aku4la-net-tools-1.60_p20170221182432/bin/arp",
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)
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.expect_err("must fail");
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}
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#[test]
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fn no_dash_between_hash_and_name() {
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StorePath::from_bytes(b"00bgd045z0d4icpbc2yyz4gx48ak44lanet-tools-1.60_p20170221182432")
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.expect_err("must fail");
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}
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#[test]
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fn absolute_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_expected =
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StorePath::from_bytes(example_nix_path_str.as_bytes()).expect("must parse");
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let nixpath_actual = StorePath::from_absolute_path(
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"/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432".as_bytes(),
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)
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.expect("must parse");
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assert_eq!(nixpath_expected, nixpath_actual);
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assert_eq!(
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"/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432",
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nixpath_actual.to_absolute_path(),
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);
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}
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#[test]
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fn absolute_path_missing_prefix() {
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assert_eq!(
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Error::MissingStoreDir(),
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StorePath::from_absolute_path(b"foobar-123").expect_err("must fail")
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);
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}
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#[test_case(
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"/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432",
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(StorePath::from_bytes(b"00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432").unwrap(), PathBuf::new())
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; "without prefix")]
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#[test_case(
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"/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432/",
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(StorePath::from_bytes(b"00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432").unwrap(), PathBuf::new())
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; "without prefix, but trailing slash")]
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#[test_case(
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"/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432/bin/arp",
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(StorePath::from_bytes(b"00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432").unwrap(), PathBuf::from("bin/arp"))
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; "with prefix")]
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#[test_case(
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"/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432/bin/arp/",
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(StorePath::from_bytes(b"00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432").unwrap(), PathBuf::from("bin/arp/"))
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; "with prefix and trailing slash")]
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fn from_absolute_path_full(s: &str, expected: (StorePath, PathBuf)) {
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let actual = StorePath::from_absolute_path_full(s).expect("must succeed");
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assert_eq!(expected, actual);
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}
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#[test]
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fn from_absolute_path_errors() {
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assert_eq!(
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Error::InvalidLength(),
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StorePath::from_absolute_path_full("/nix/store/").expect_err("must fail")
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);
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assert_eq!(
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Error::InvalidLength(),
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StorePath::from_absolute_path_full("/nix/store/foo").expect_err("must fail")
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);
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assert_eq!(
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Error::MissingStoreDir(),
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StorePath::from_absolute_path_full(
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"00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432"
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)
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.expect_err("must fail")
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);
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}
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}
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