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