refactor(tvix/nix-compat): cleanup parse_{ca,hash} and fmt structs r/7045

These were used to format to and parse from strings.

Move this to the CAHash and NixHash structs directly, and be explicit in
the name about which encoding for digests is used.

For output path calculation, nix encodes the nixpaths in hex, but for
writing out NARInfos, it's using nixbase32.

Change-Id: Ia585a76a3811b2609e7ce259fda66a29403b7e07
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10079
Reviewed-by: raitobezarius <tvl@lahfa.xyz>
Tested-by: BuildkiteCI
Autosubmit: flokli <flokli@flokli.de>

1 files changed, 6 insertions, 80 deletions

diff --git a/tvix/nix-compat/src/narinfo/mod.rs b/tvix/nix-compat/src/narinfo/mod.rs
index e64fb10d7ac8..3fa73103bde6 100644
--- a/tvix/nix-compat/src/narinfo/mod.rs
+++ b/tvix/nix-compat/src/narinfo/mod.rs
@@ -24,11 +24,7 @@ use std::{
     mem,
 };
 
-use crate::{
-    nixbase32,
-    nixhash::{CAHash, NixHash},
-    store_path::StorePathRef,
-};
+use crate::{nixbase32, nixhash::CAHash, store_path::StorePathRef};
 
 mod fingerprint;
 mod signature;
@@ -249,8 +245,8 @@ impl<'a> NarInfo<'a> {
                     signatures.push(val);
                 }
                 "CA" => {
-                    let val =
-                        parse_ca(val).ok_or_else(|| Error::UnableToParseCA(val.to_string()))?;
+                    let val = CAHash::from_nix_hex_str(val)
+                        .ok_or_else(|| Error::UnableToParseCA(val.to_string()))?;
 
                     if ca.replace(val).is_some() {
                         return Err(Error::DuplicateField(tag.to_string()));
@@ -308,14 +304,14 @@ impl Display for NarInfo<'_> {
         }
 
         if let Some(file_hash) = self.file_hash {
-            writeln!(w, "FileHash: {}", fmt_hash(&NixHash::Sha256(file_hash)))?;
+            writeln!(w, "FileHash: sha256:{}", nixbase32::encode(&file_hash),)?;
         }
 
         if let Some(file_size) = self.file_size {
             writeln!(w, "FileSize: {file_size}")?;
         }
 
-        writeln!(w, "NarHash: {}", fmt_hash(&NixHash::Sha256(self.nar_hash)))?;
+        writeln!(w, "NarHash: sha256:{}", nixbase32::encode(&self.nar_hash),)?;
         writeln!(w, "NarSize: {}", self.nar_size)?;
 
         write!(w, "References:")?;
@@ -341,83 +337,13 @@ impl Display for NarInfo<'_> {
         }
 
         if let Some(ca) = &self.ca {
-            writeln!(w, "CA: {}", fmt_ca(ca))?;
+            writeln!(w, "CA: {}", ca.to_nix_nixbase32_string())?;
         }
 
         Ok(())
     }
 }
 
-pub fn parse_ca(s: &str) -> Option<CAHash> {
-    let (tag, s) = s.split_once(':')?;
-
-    match tag {
-        "text" => {
-            let digest = s.strip_prefix("sha256:")?;
-            let digest = nixbase32::decode_fixed(digest).ok()?;
-            Some(CAHash::Text(digest))
-        }
-        "fixed" => {
-            if let Some(s) = s.strip_prefix("r:") {
-                parse_hash(s).map(CAHash::Nar)
-            } else {
-                parse_hash(s).map(CAHash::Flat)
-            }
-        }
-        _ => None,
-    }
-}
-
-#[allow(non_camel_case_types)]
-struct fmt_ca<'a>(&'a CAHash);
-
-impl Display for fmt_ca<'_> {
-    fn fmt(&self, w: &mut fmt::Formatter) -> fmt::Result {
-        match self.0 {
-            CAHash::Flat(h) => {
-                write!(w, "fixed:{}", fmt_hash(h))
-            }
-            &CAHash::Text(d) => {
-                write!(w, "text:{}", fmt_hash(&NixHash::Sha256(d)))
-            }
-            CAHash::Nar(h) => {
-                write!(w, "fixed:r:{}", fmt_hash(h))
-            }
-        }
-    }
-}
-
-fn parse_hash(s: &str) -> Option<NixHash> {
-    let (tag, digest) = s.split_once(':')?;
-
-    (match tag {
-        "md5" => nixbase32::decode_fixed(digest).map(NixHash::Md5),
-        "sha1" => nixbase32::decode_fixed(digest).map(NixHash::Sha1),
-        "sha256" => nixbase32::decode_fixed(digest).map(NixHash::Sha256),
-        "sha512" => nixbase32::decode_fixed(digest)
-            .map(Box::new)
-            .map(NixHash::Sha512),
-        _ => return None,
-    })
-    .ok()
-}
-
-#[allow(non_camel_case_types)]
-struct fmt_hash<'a>(&'a NixHash);
-
-impl Display for fmt_hash<'_> {
-    fn fmt(&self, w: &mut fmt::Formatter) -> fmt::Result {
-        let (tag, digest) = match self.0 {
-            NixHash::Md5(d) => ("md5", &d[..]),
-            NixHash::Sha1(d) => ("sha1", &d[..]),
-            NixHash::Sha256(d) => ("sha256", &d[..]),
-            NixHash::Sha512(d) => ("sha512", &d[..]),
-        };
-
-        write!(w, "{tag}:{}", nixbase32::encode(digest))
-    }
-}
-
 #[derive(thiserror::Error, Debug)]
 pub enum Error {
     #[error("duplicate field: {0}")]