refactor(tvix/nix-compat): rename NixHashWithMode -> CAHash r/6871

This specific struct is only used to represent content-addressed paths
(in case a Derivation has a fixed-output hash, for example).
Rename `Output`'s `hash_with_mode` to `ca_hash`.

We now also include `CAHash::Text`, and update the `validate` function
of the `Output` struct to reject text hashes there.

This allows cleaning up the various output path calculation functions
inside nix-compat/src/store_path/utils.rs, as they can now match on
the type.

`make_type` is renamed to `make_references_string`,
`build_regular_ca_path` is renamed to `build_ca_path`, and
`build_text_path` has a disclaimer added, because you might not actually
want to use it.

Change-Id: I674d065f2ed5c804012ddfed56e161ac49d23931
Reviewed-on: https://cl.tvl.fyi/c/depot/+/9814
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>

1 files changed, 0 insertions, 234 deletions

diff --git a/tvix/nix-compat/src/nixhash/with_mode.rs b/tvix/nix-compat/src/nixhash/with_mode.rs
deleted file mode 100644
index 6e6d2e76b4a4..000000000000
--- a/tvix/nix-compat/src/nixhash/with_mode.rs
+++ /dev/null
@@ -1,234 +0,0 @@
-use crate::nixbase32;
-use crate::nixhash::{self, HashAlgo, NixHash};
-use serde::de::Unexpected;
-use serde::ser::SerializeMap;
-use serde::{Deserialize, Deserializer, Serialize, Serializer};
-use serde_json::{Map, Value};
-
-use super::algos::SUPPORTED_ALGOS;
-use super::from_algo_and_digest;
-
-pub enum NixHashMode {
-    Flat,
-    Recursive,
-}
-
-impl NixHashMode {
-    pub fn prefix(self) -> &'static str {
-        match self {
-            Self::Flat => "",
-            Self::Recursive => "r:",
-        }
-    }
-}
-
-/// A Nix Hash can either be flat or recursive.
-#[derive(Clone, Debug, Eq, PartialEq)]
-pub enum NixHashWithMode {
-    Flat(NixHash),
-    Recursive(NixHash),
-}
-
-impl NixHashWithMode {
-    /// Construct a [NixHashWithMode] from a string containing the algo, and
-    /// optionally a `r:` prefix, and a digest (bytes).
-    pub fn from_algo_mode_hash(algo_and_mode: &str, digest: &[u8]) -> super::Result<Self> {
-        Ok(match algo_and_mode.strip_prefix("r:") {
-            Some(algo) => nixhash::NixHashWithMode::Recursive(nixhash::from_algo_and_digest(
-                algo.try_into()?,
-                digest,
-            )?),
-            None => nixhash::NixHashWithMode::Flat(nixhash::from_algo_and_digest(
-                algo_and_mode.try_into()?,
-                digest,
-            )?),
-        })
-    }
-
-    pub fn mode(&self) -> NixHashMode {
-        match self {
-            Self::Flat(_) => NixHashMode::Flat,
-            Self::Recursive(_) => NixHashMode::Recursive,
-        }
-    }
-
-    pub fn digest(&self) -> &NixHash {
-        match self {
-            Self::Flat(ref h) => h,
-            Self::Recursive(ref h) => h,
-        }
-    }
-
-    /// Formats a [NixHashWithMode] in the Nix default hash format,
-    /// which is the algo, followed by a colon, then the lower hex encoded digest.
-    /// In case the hash itself is recursive, a `r:` is added as prefix
-    pub fn to_nix_hash_string(&self) -> String {
-        String::from(self.mode().prefix()) + &self.digest().to_nix_hash_string()
-    }
-
-    /// This takes a serde_json::Map and turns it into this structure. This is necessary to do such
-    /// shenigans because we have external consumers, like the Derivation parser, who would like to
-    /// know whether we have a invalid or a missing NixHashWithMode structure in another structure,
-    /// e.g. Output.
-    /// This means we have this combinatorial situation:
-    /// - no hash, no hashAlgo: no NixHashWithMode so we return Ok(None).
-    /// - present hash, missing hashAlgo: invalid, we will return missing_field
-    /// - missing hash, present hashAlgo: same
-    /// - present hash, present hashAlgo: either we return ourselves or a type/value validation
-    /// error.
-    /// This function is for internal consumption regarding those needs until we have a better
-    /// solution. Now this is said, let's explain how this works.
-    ///
-    /// We want to map the serde data model into a NixHashWithMode.
-    ///
-    /// The serde data model has a `hash` field (containing a digest in nixbase32),
-    /// and a `hashAlgo` field, containing the stringified hash algo.
-    /// In case the hash is recursive, hashAlgo also has a `r:` prefix.
-    ///
-    /// This is to match how `nix show-derivation` command shows them in JSON
-    /// representation.
-    pub(crate) fn from_map<'de, D>(map: &Map<String, Value>) -> Result<Option<Self>, D::Error>
-    where
-        D: Deserializer<'de>,
-    {
-        // If we don't have hash neither hashAlgo, let's just return None.
-        if !map.contains_key("hash") && !map.contains_key("hashAlgo") {
-            return Ok(None);
-        }
-
-        let digest: Vec<u8> = {
-            if let Some(v) = map.get("hash") {
-                if let Some(s) = v.as_str() {
-                    data_encoding::HEXLOWER
-                        .decode(s.as_bytes())
-                        .map_err(|e| serde::de::Error::custom(e.to_string()))?
-                } else {
-                    return Err(serde::de::Error::invalid_type(
-                        Unexpected::Other(&v.to_string()),
-                        &"a string",
-                    ));
-                }
-            } else {
-                return Err(serde::de::Error::missing_field(
-                    "couldn't extract `hash` key but `hashAlgo` key present",
-                ));
-            }
-        };
-
-        if let Some(v) = map.get("hashAlgo") {
-            if let Some(s) = v.as_str() {
-                match s.strip_prefix("r:") {
-                    Some(rest) => Ok(Some(Self::Recursive(
-                        from_algo_and_digest(
-                            HashAlgo::try_from(rest).map_err(|e| {
-                                serde::de::Error::invalid_value(
-                                    Unexpected::Other(&e.to_string()),
-                                    &format!("one of {}", SUPPORTED_ALGOS.join(",")).as_str(),
-                                )
-                            })?,
-                            &digest,
-                        )
-                        .map_err(|e: nixhash::Error| {
-                            serde::de::Error::invalid_value(
-                                Unexpected::Other(&e.to_string()),
-                                &"a digest with right length",
-                            )
-                        })?,
-                    ))),
-                    None => Ok(Some(Self::Flat(
-                        from_algo_and_digest(
-                            HashAlgo::try_from(s).map_err(|e| {
-                                serde::de::Error::invalid_value(
-                                    Unexpected::Other(&e.to_string()),
-                                    &format!("one of {}", SUPPORTED_ALGOS.join(",")).as_str(),
-                                )
-                            })?,
-                            &digest,
-                        )
-                        .map_err(|e: nixhash::Error| {
-                            serde::de::Error::invalid_value(
-                                Unexpected::Other(&e.to_string()),
-                                &"a digest with right length",
-                            )
-                        })?,
-                    ))),
-                }
-            } else {
-                Err(serde::de::Error::invalid_type(
-                    Unexpected::Other(&v.to_string()),
-                    &"a string",
-                ))
-            }
-        } else {
-            Err(serde::de::Error::missing_field(
-                "couldn't extract `hashAlgo` key, but `hash` key present",
-            ))
-        }
-    }
-}
-
-impl Serialize for NixHashWithMode {
-    /// map a NixHashWithMode into the serde data model.
-    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
-    where
-        S: Serializer,
-    {
-        let mut map = serializer.serialize_map(Some(2))?;
-        match self {
-            NixHashWithMode::Flat(h) => {
-                map.serialize_entry("hash", &nixbase32::encode(h.digest_as_bytes()))?;
-                map.serialize_entry("hashAlgo", &h.algo())?;
-            }
-            NixHashWithMode::Recursive(h) => {
-                map.serialize_entry("hash", &nixbase32::encode(h.digest_as_bytes()))?;
-                map.serialize_entry("hashAlgo", &format!("r:{}", &h.algo()))?;
-            }
-        };
-        map.end()
-    }
-}
-
-impl<'de> Deserialize<'de> for NixHashWithMode {
-    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
-    where
-        D: Deserializer<'de>,
-    {
-        let value = Self::from_map::<D>(&Map::deserialize(deserializer)?)?;
-
-        match value {
-            None => Err(serde::de::Error::custom("couldn't parse as map")),
-            Some(v) => Ok(v),
-        }
-    }
-}
-
-#[cfg(test)]
-mod tests {
-    use crate::nixhash::{NixHash, NixHashWithMode};
-    use lazy_static::lazy_static;
-    use test_case::test_case;
-
-    const DIGEST_SHA256: [u8; 32] = [
-        0xa5, 0xce, 0x9c, 0x15, 0x5e, 0xd0, 0x93, 0x97, 0x61, 0x46, 0x46, 0xc9, 0x71, 0x7f, 0xc7,
-        0xcd, 0x94, 0xb1, 0x02, 0x3d, 0x7b, 0x76, 0xb6, 0x18, 0xd4, 0x09, 0xe4, 0xfe, 0xfd, 0x6e,
-        0x9d, 0x39,
-    ];
-    lazy_static! {
-        pub static ref NIXHASH_SHA256: NixHash = NixHash::Sha256(DIGEST_SHA256);
-    }
-
-    #[test_case("sha256", &DIGEST_SHA256, NixHashWithMode::Flat(NIXHASH_SHA256.clone()); "sha256 flat")]
-    #[test_case("r:sha256", &DIGEST_SHA256, NixHashWithMode::Recursive(NIXHASH_SHA256.clone()); "sha256 recursive")]
-    fn from_from_algo_mode_hash(algo_and_mode: &str, digest: &[u8], expected: NixHashWithMode) {
-        assert_eq!(
-            expected,
-            NixHashWithMode::from_algo_mode_hash(algo_and_mode, digest).unwrap()
-        );
-    }
-
-    #[test]
-    fn from_algo_mode_failure() {
-        assert!(NixHashWithMode::from_algo_mode_hash("r:sha256", &[]).is_err());
-        assert!(NixHashWithMode::from_algo_mode_hash("ha256", &DIGEST_SHA256).is_err());
-    }
-}