diff options
Diffstat (limited to 'tvix/nix-compat/src/nixhash')
| -rw-r--r-- | tvix/nix-compat/src/nixhash/algos.rs | 5 | ||||
| -rw-r--r-- | tvix/nix-compat/src/nixhash/with_mode.rs | 149 |
2 files changed, 97 insertions, 57 deletions
diff --git a/tvix/nix-compat/src/nixhash/algos.rs b/tvix/nix-compat/src/nixhash/algos.rs index d6b0bf47bdb7..45cc242dc330 100644 --- a/tvix/nix-compat/src/nixhash/algos.rs +++ b/tvix/nix-compat/src/nixhash/algos.rs @@ -24,6 +24,11 @@ impl Display for HashAlgo { } } +/// TODO(Raito): this could be automated via macros, I suppose. +/// But this may be more expensive than just doing it by hand +/// and ensuring that is kept in sync. +pub const SUPPORTED_ALGOS: [&str; 4] = ["md5", "sha1", "sha256", "sha512"]; + impl TryFrom<&str> for HashAlgo { type Error = Error; diff --git a/tvix/nix-compat/src/nixhash/with_mode.rs b/tvix/nix-compat/src/nixhash/with_mode.rs index 1908f27b4759..344322046614 100644 --- a/tvix/nix-compat/src/nixhash/with_mode.rs +++ b/tvix/nix-compat/src/nixhash/with_mode.rs @@ -1,7 +1,11 @@ use crate::nixbase32; use crate::nixhash::{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; pub enum NixHashMode { Flat, @@ -45,6 +49,90 @@ impl NixHashWithMode { 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(NixHash::new( + 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, + )))), + None => Ok(Some(Self::Flat(NixHash::new( + 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, + )))), + } + } 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 { @@ -69,68 +157,15 @@ impl Serialize for NixHashWithMode { } impl<'de> Deserialize<'de> for NixHashWithMode { - /// 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. fn deserialize<D>(deserializer: D) -> Result<Self, D::Error> where D: Deserializer<'de>, { - // TODO: don't use serde_json here? - // TODO: serde seems to simply set `hash_with_mode` to None if hash - // and hashAlgo fail, but that should be a proper deserialization error - // that should be propagated to the user! + let value = Self::from_map::<D>(&Map::deserialize(deserializer)?)?; - let json = serde_json::Value::deserialize(deserializer)?; - match json.as_object() { - None => Err(serde::de::Error::custom("couldn't parse as map"))?, - Some(map) => { - 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::custom( - "couldn't parse 'hash' as string", - )); - } - } else { - return Err(serde::de::Error::custom("couldn't extract 'hash' key")); - } - }; - - if let Some(v) = map.get("hashAlgo") { - if let Some(s) = v.as_str() { - match s.strip_prefix("r:") { - Some(rest) => Ok(NixHashWithMode::Recursive(NixHash::new( - HashAlgo::try_from(rest).map_err(|e| { - serde::de::Error::custom(format!("unable to parse algo: {}", e)) - })?, - digest, - ))), - None => Ok(NixHashWithMode::Flat(NixHash::new( - HashAlgo::try_from(s).map_err(|e| { - serde::de::Error::custom(format!("unable to parse algo: {}", e)) - })?, - digest, - ))), - } - } else { - Err(serde::de::Error::custom( - "couldn't parse 'hashAlgo' as string", - )) - } - } else { - Err(serde::de::Error::custom("couldn't extract 'hashAlgo' key")) - } - } + match value { + None => Err(serde::de::Error::custom("couldn't parse as map")), + Some(v) => Ok(v), } } } |