diff options
Diffstat (limited to 'tvix/nix-compat/src/store_path/mod.rs')
| -rw-r--r-- | tvix/nix-compat/src/store_path/mod.rs | 635 |
1 files changed, 635 insertions, 0 deletions
diff --git a/tvix/nix-compat/src/store_path/mod.rs b/tvix/nix-compat/src/store_path/mod.rs new file mode 100644 index 0000000000..ff7ede77e1 --- /dev/null +++ b/tvix/nix-compat/src/store_path/mod.rs @@ -0,0 +1,635 @@ +use crate::nixbase32; +use data_encoding::{DecodeError, BASE64}; +use serde::{Deserialize, Serialize}; +use std::{ + fmt, + path::PathBuf, + str::{self, FromStr}, +}; +use thiserror; + +#[cfg(target_family = "unix")] +use std::os::unix::ffi::OsStringExt; + +mod utils; + +pub use utils::*; + +pub const DIGEST_SIZE: usize = 20; +pub const ENCODED_DIGEST_SIZE: usize = nixbase32::encode_len(DIGEST_SIZE); + +// 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(#[from] DecodeError), + #[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>, u8), + #[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 { + digest: [u8; DIGEST_SIZE], + name: String, +} + +impl StorePath { + pub fn digest(&self) -> &[u8; DIGEST_SIZE] { + &self.digest + } + + pub fn name(&self) -> &str { + self.name.as_ref() + } + + pub fn as_ref(&self) -> StorePathRef<'_> { + StorePathRef { + digest: self.digest, + name: &self.name, + } + } +} + +impl PartialOrd for StorePath { + fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> { + Some(self.cmp(other)) + } +} + +/// `StorePath`s are sorted by their reverse digest to match the sorting order +/// of the nixbase32-encoded string. +impl Ord for StorePath { + fn cmp(&self, other: &Self) -> std::cmp::Ordering { + self.as_ref().cmp(&other.as_ref()) + } +} + +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> { + Ok(StorePathRef::from_bytes(s)?.to_owned()) + } + + /// 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 "/"? + } + } + } + } + + /// Returns 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 { + let sp_ref: StorePathRef = self.into(); + sp_ref.to_absolute_path() + } +} + +impl<'de> Deserialize<'de> for StorePath { + fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> + where + D: serde::Deserializer<'de>, + { + let r = <StorePathRef<'de> as Deserialize<'de>>::deserialize(deserializer)?; + Ok(r.to_owned()) + } +} + +impl Serialize for StorePath { + fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> + where + S: serde::Serializer, + { + let r: StorePathRef = self.into(); + r.serialize(serializer) + } +} + +/// Like [StorePath], but without a heap allocation for the name. +/// Used by [StorePath] for parsing. +/// +#[derive(Debug, Eq, PartialEq, Clone, Copy, Hash)] +pub struct StorePathRef<'a> { + digest: [u8; DIGEST_SIZE], + name: &'a str, +} + +impl<'a> From<&'a StorePath> for StorePathRef<'a> { + fn from(&StorePath { digest, ref name }: &'a StorePath) -> Self { + StorePathRef { + digest, + name: name.as_ref(), + } + } +} + +impl<'a> PartialOrd for StorePathRef<'a> { + fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> { + Some(self.cmp(other)) + } +} + +/// `StorePathRef`s are sorted by their reverse digest to match the sorting order +/// of the nixbase32-encoded string. +impl<'a> Ord for StorePathRef<'a> { + fn cmp(&self, other: &Self) -> std::cmp::Ordering { + self.digest.iter().rev().cmp(other.digest.iter().rev()) + } +} + +impl<'a> StorePathRef<'a> { + pub fn digest(&self) -> &[u8; DIGEST_SIZE] { + &self.digest + } + + pub fn name(&self) -> &'a str { + self.name + } + + pub fn to_owned(&self) -> StorePath { + StorePath { + digest: self.digest, + name: self.name.to_owned(), + } + } + + /// Construct a [StorePathRef] from a name and digest. + /// The name is validated, and the digest checked for size. + pub fn from_name_and_digest(name: &'a str, digest: &[u8]) -> Result<Self, Error> { + let digest_fixed = digest.try_into().map_err(|_| Error::InvalidLength)?; + Self::from_name_and_digest_fixed(name, digest_fixed) + } + + /// Construct a [StorePathRef] from a name and digest of correct length. + /// The name is validated. + pub fn from_name_and_digest_fixed( + name: &'a str, + digest: [u8; DIGEST_SIZE], + ) -> Result<Self, Error> { + Ok(Self { + name: validate_name(name.as_bytes())?, + digest, + }) + } + + /// Construct a [StorePathRef] from an absolute store path string. + /// This is equivalent to calling [StorePathRef::from_bytes], but stripping + /// the [STORE_DIR_WITH_SLASH] prefix before. + pub fn from_absolute_path(s: &'a [u8]) -> Result<Self, 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 [StorePathRef] by passing the `$digest-$name` string + /// that comes after [STORE_DIR_WITH_SLASH]. + pub fn from_bytes(s: &'a [u8]) -> Result<Self, 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 = nixbase32::decode_fixed(&s[..ENCODED_DIGEST_SIZE])?; + + if s[ENCODED_DIGEST_SIZE] != b'-' { + return Err(Error::MissingDash); + } + + Ok(StorePathRef { + digest, + name: validate_name(&s[ENCODED_DIGEST_SIZE + 1..])?, + }) + } + + /// Returns 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) + } +} + +impl<'de: 'a, 'a> Deserialize<'de> for StorePathRef<'a> { + fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> + where + D: serde::Deserializer<'de>, + { + let string: &'de str = Deserialize::deserialize(deserializer)?; + let stripped: Option<&str> = string.strip_prefix(STORE_DIR_WITH_SLASH); + let stripped: &str = stripped.ok_or_else(|| { + serde::de::Error::invalid_value( + serde::de::Unexpected::Str(string), + &"store path prefix", + ) + })?; + StorePathRef::from_bytes(stripped.as_bytes()).map_err(|_| { + serde::de::Error::invalid_value(serde::de::Unexpected::Str(string), &"StorePath") + }) + } +} + +impl Serialize for StorePathRef<'_> { + fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error> + where + S: serde::Serializer, + { + let string: String = self.to_absolute_path(); + string.serialize(serializer) + } +} + +/// NAME_CHARS contains `true` for bytes that are valid in store path names. +static NAME_CHARS: [bool; 256] = { + let mut tbl = [false; 256]; + let mut c = 0; + + loop { + tbl[c as usize] = matches!(c, b'a'..=b'z' | b'A'..=b'Z' | b'0'..=b'9' | b'+' | b'-' | b'_' | b'?' | b'=' | b'.'); + + if c == u8::MAX { + break; + } + + c += 1; + } + + tbl +}; + +/// 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: &(impl AsRef<[u8]> + ?Sized)) -> Result<&str, Error> { + let s = s.as_ref(); + + // Empty or excessively long names are not allowed. + if s.is_empty() || s.len() > 211 { + return Err(Error::InvalidLength); + } + + let mut valid = true; + for &c in s { + valid = valid && NAME_CHARS[c as usize]; + } + + if !valid { + for (i, &c) in s.iter().enumerate() { + if !NAME_CHARS[c as usize] { + return Err(Error::InvalidName(s.to_vec(), i as u8)); + } + } + + unreachable!(); + } + + // SAFETY: We permit a subset of ASCII, which guarantees valid UTF-8. + Ok(unsafe { str::from_utf8_unchecked(s) }) +} + +impl fmt::Display for StorePath { + fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result { + StorePathRef::from(self).fmt(f) + } +} + +impl fmt::Display for StorePathRef<'_> { + /// 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 super::Error; + use std::cmp::Ordering; + use std::path::PathBuf; + + use crate::store_path::{StorePath, StorePathRef, DIGEST_SIZE}; + use hex_literal::hex; + use pretty_assertions::assert_eq; + use rstest::rstest; + use serde::Deserialize; + + #[derive(Deserialize)] + /// An example struct, holding a StorePathRef. + /// Used to test deserializing StorePathRef. + struct Container<'a> { + #[serde(borrow)] + store_path: StorePathRef<'a>, + } + + #[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()) + } + + #[test] + fn store_path_ordering() { + let store_paths = [ + "/nix/store/0lk5dgi01r933abzfj9c9wlndg82yd3g-psutil-5.9.6.tar.gz.drv", + "/nix/store/1xj43bva89f9qmwm37zl7r3d7m67i9ck-shorttoc-1.3-tex.drv", + "/nix/store/2gb633czchi20jq1kqv70rx2yvvgins8-lifted-base-0.2.3.12.tar.gz.drv", + "/nix/store/2vksym3r3zqhp15q3fpvw2mnvffv11b9-docbook-xml-4.5.zip.drv", + "/nix/store/5q918awszjcz5720xvpc2czbg1sdqsf0-rust_renaming-0.1.0-lib", + "/nix/store/7jw30i342sr2p1fmz5xcfnch65h4zbd9-dbus-1.14.10.tar.xz.drv", + "/nix/store/96yqwqhnp3qya4rf4n0rcl0lwvrylp6k-eap8021x-222.40.1.tar.gz.drv", + "/nix/store/9gjqg36a1v0axyprbya1hkaylmnffixg-virtualenv-20.24.5.tar.gz.drv", + "/nix/store/a4i5mci2g9ada6ff7ks38g11dg6iqyb8-perl-5.32.1.drv", + "/nix/store/a5g76ljava4h5pxlggz3aqdhs3a4fk6p-ToolchainInfo.plist.drv", + "/nix/store/db46l7d6nswgz4ffp1mmd56vjf9g51v6-version.plist.drv", + "/nix/store/g6f7w20sd7vwy0rc1r4bfsw4ciclrm4q-crates-io-num_cpus-1.12.0.drv", + "/nix/store/iw82n1wwssb8g6772yddn8c3vafgv9np-bootstrap-stage1-sysctl-stdenv-darwin.drv", + "/nix/store/lp78d1y5wxpcn32d5c4r7xgbjwiw0cgf-logo.svg.drv", + "/nix/store/mf00ank13scv1f9l1zypqdpaawjhfr3s-python3.11-psutil-5.9.6.drv", + "/nix/store/mpfml61ra7pz90124jx9r3av0kvkz2w1-perl5.36.0-Encode-Locale-1.05", + "/nix/store/qhsvwx4h87skk7c4mx0xljgiy3z93i23-source.drv", + "/nix/store/riv7d73adim8hq7i04pr8kd0jnj93nav-fdk-aac-2.0.2.tar.gz.drv", + "/nix/store/s64b9031wga7vmpvgk16xwxjr0z9ln65-human-signals-5.0.0.tgz-extracted", + "/nix/store/w6svg3m2xdh6dhx0gl1nwa48g57d3hxh-thiserror-1.0.49", + ]; + + for w in store_paths.windows(2) { + if w.len() < 2 { + continue; + } + let (pa, _) = StorePath::from_absolute_path_full(w[0]).expect("parseable"); + let (pb, _) = StorePath::from_absolute_path_full(w[1]).expect("parseable"); + assert_eq!( + Ordering::Less, + pa.cmp(&pb), + "{:?} not less than {:?}", + w[0], + w[1] + ); + } + } + + /// This is the store path *accepted* when `nix-store --add`'ing an + /// empty `.gitignore` file. + /// + /// Nix 2.4 accidentally permitted this behaviour, but the revert came + /// too late to beat Hyrum's law. It is now considered permissible. + /// + /// https://github.com/NixOS/nix/pull/9095 (revert) + /// https://github.com/NixOS/nix/pull/9867 (revert-of-revert) + #[test] + fn starts_with_dot() { + StorePath::from_bytes(b"fli4bwscgna7lpm7v5xgnjxrxh0yc7ra-.gitignore") + .expect("must succeed"); + } + + #[test] + fn empty_name() { + StorePath::from_bytes(b"00bgd045z0d4icpbc2yy-").expect_err("must fail"); + } + + #[test] + fn excessive_length() { + StorePath::from_bytes(b"00bgd045z0d4icpbc2yy-aaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaaa") + .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 = + StorePathRef::from_bytes(example_nix_path_str.as_bytes()).expect("must parse"); + + let nixpath_actual = StorePathRef::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, + StorePathRef::from_absolute_path(b"foobar-123").expect_err("must fail") + ); + } + + #[test] + fn serialize_ref() { + let nixpath_actual = StorePathRef::from_bytes( + b"00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432", + ) + .expect("can parse"); + + let serialized = serde_json::to_string(&nixpath_actual).expect("can serialize"); + + assert_eq!( + "\"/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432\"", + &serialized + ); + } + + #[test] + fn serialize_owned() { + let nixpath_actual = StorePath::from_bytes( + b"00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432", + ) + .expect("can parse"); + + let serialized = serde_json::to_string(&nixpath_actual).expect("can serialize"); + + assert_eq!( + "\"/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432\"", + &serialized + ); + } + + #[test] + fn deserialize_ref() { + let store_path_str_json = + "\"/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432\""; + + let store_path: StorePathRef<'_> = + serde_json::from_str(store_path_str_json).expect("valid json"); + + assert_eq!( + "/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432", + store_path.to_absolute_path() + ); + } + + #[test] + fn deserialize_ref_container() { + let str_json = "{\"store_path\":\"/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432\"}"; + + let container: Container<'_> = serde_json::from_str(str_json).expect("must deserialize"); + + assert_eq!( + "/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432", + container.store_path.to_absolute_path() + ); + } + + #[test] + fn deserialize_owned() { + let store_path_str_json = + "\"/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432\""; + + let store_path: StorePath = serde_json::from_str(store_path_str_json).expect("valid json"); + + assert_eq!( + "/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432", + store_path.to_absolute_path() + ); + } + + #[rstest] + #[case::without_prefix( + "/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432", + StorePath::from_bytes(b"00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432").unwrap(), PathBuf::new())] + #[case::without_prefix_but_trailing_slash( + "/nix/store/00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432/", + StorePath::from_bytes(b"00bgd045z0d4icpbc2yyz4gx48ak44la-net-tools-1.60_p20170221182432").unwrap(), PathBuf::new())] + #[case::with_prefix( + "/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"))] + #[case::with_prefix_and_trailing_slash( + "/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/"))] + fn from_absolute_path_full( + #[case] s: &str, + #[case] exp_store_path: StorePath, + #[case] exp_path: PathBuf, + ) { + let (actual_store_path, actual_path) = + StorePath::from_absolute_path_full(s).expect("must succeed"); + + assert_eq!(exp_store_path, actual_store_path); + assert_eq!(exp_path, actual_path); + } + + #[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") + ); + } +} |