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author | John Ericson <John.Ericson@Obsidian.Systems> | 2023-03-31T12·27-0400 |
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committer | John Ericson <git@johnericson.me> | 2023-03-31T18·46+0000 |
commit | b932cf2d85af64a383f8020394301889f5df04c5 (patch) | |
tree | 2e392ee1927363ed7728b275829b058da7eb319e /tvix/nix-compat/src/nixhash/with_mode.rs | |
parent | df78a4d24ee88289d979c2068ddf59d949c41004 (diff) |
refactor(nix-compat) Make `nixhash_*` mods hierarchical r/6068
They can go under `nixhash` Change-Id: Ia15835c57130b66d58f5df80ae9595dceee00941 Reviewed-on: https://cl.tvl.fyi/c/depot/+/8408 Reviewed-by: flokli <flokli@flokli.de> Tested-by: BuildkiteCI
Diffstat (limited to 'tvix/nix-compat/src/nixhash/with_mode.rs')
-rw-r--r-- | tvix/nix-compat/src/nixhash/with_mode.rs | 111 |
1 files changed, 111 insertions, 0 deletions
diff --git a/tvix/nix-compat/src/nixhash/with_mode.rs b/tvix/nix-compat/src/nixhash/with_mode.rs new file mode 100644 index 000000000000..e895f0c62704 --- /dev/null +++ b/tvix/nix-compat/src/nixhash/with_mode.rs @@ -0,0 +1,111 @@ +use crate::nixbase32; +use crate::nixhash::{HashAlgo, NixHash}; +use serde::ser::SerializeMap; +use serde::{Deserialize, Deserializer, Serialize, Serializer}; + +/// A Nix Hash can either be flat or recursive. +#[derive(Clone, Debug, Eq, PartialEq)] +pub enum NixHashWithMode { + Flat(NixHash), + Recursive(NixHash), +} + +impl NixHashWithMode { + /// 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 { + match self { + NixHashWithMode::Flat(h) => h.to_nix_hash_string(), + NixHashWithMode::Recursive(h) => format!("r:{}", h.to_nix_hash_string()), + } + } +} + +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))?; + map.serialize_entry("hashAlgo", &h.algo.to_string())?; + } + NixHashWithMode::Recursive(h) => { + map.serialize_entry("hash", &nixbase32::encode(&h.digest))?; + map.serialize_entry("hashAlgo", &format!("r:{}", &h.algo.to_string()))?; + } + }; + map.end() + } +} + +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 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")) + } + } + } + } +} |