diff options
| -rw-r--r-- | tvix/nix-compat/src/derivation/mod.rs | 130 |
1 files changed, 54 insertions, 76 deletions
diff --git a/tvix/nix-compat/src/derivation/mod.rs b/tvix/nix-compat/src/derivation/mod.rs index 06b7ba02f4..d5857c1a69 100644 --- a/tvix/nix-compat/src/derivation/mod.rs +++ b/tvix/nix-compat/src/derivation/mod.rs @@ -236,86 +236,64 @@ impl Derivation { name: &str, derivation_or_fod_hash: &NixHash, ) -> Result<(), DerivationError> { - // Check if the Derivation is fixed output, because they cause - // different fingerprints to be hashed. - match self.get_fixed_output() { - None => { - // The fingerprint and hash differs per output - for (output_name, output) in self.outputs.iter_mut() { - // Assert that outputs are not yet populated, to avoid using this function wrongly. - // We don't also go over self.environment, but it's a sufficient - // footgun prevention mechanism. - assert!(output.path.is_empty()); - - // calculate the output_name_path, which is the part of the NixPath after the digest. - let mut output_path_name = name.to_string(); - if output_name != "out" { - output_path_name.push('-'); - output_path_name.push_str(output_name); - } - - let fp = &format!( - "output:{}:{}:{}:{}", - output_name, - derivation_or_fod_hash.to_nix_hash_string(), - store_path::STORE_DIR, - output_path_name, - ); - - let abs_store_path = - utils::build_store_path(false, fp, &output_path_name)?.to_absolute_path(); - - output.path = abs_store_path.clone(); - self.environment - .insert(output_name.to_string(), abs_store_path); + let num_outputs = self.outputs.len(); + // The fingerprint and hash differs per output + for (output_name, output) in self.outputs.iter_mut() { + // Assert that outputs are not yet populated, to avoid using this function wrongly. + // We don't also go over self.environment, but it's a sufficient + // footgun prevention mechanism. + assert!(output.path.is_empty()); + + // calculate the output_name_path, which is the part of the NixPath after the digest. + // It's the name, and (if it's the non-out output), the output name after a `-`. + let output_path_name = { + let mut output_path_name = name.to_string(); + if output_name != "out" { + output_path_name.push('-'); + output_path_name.push_str(output_name); } - } - Some((fixed_output_path, fixed_output_hash)) => { - // Assert that outputs are not yet populated, to avoid using this function wrongly. - // We don't also go over self.environment, but it's a sufficient - // footgun prevention mechanism. - assert!(fixed_output_path.is_empty()); - - let fp = { - let mut fp = String::new(); - // Fixed-output derivation. - // There's two different hashing strategies in place, - // depending on whether the hash is recursive AND sha256 or anything else. - // This code is _weird_ but it is what Nix is doing. See: - // https://github.com/NixOS/nix/blob/1385b2007804c8a0370f2a6555045a00e34b07c7/src/libstore/store-api.cc#L178-L196 - if let NixHashWithMode::Recursive(recursive_hash) = fixed_output_hash { - if recursive_hash.algo == HashAlgo::Sha256 { - fp.push_str(&format!("source:{}", recursive_hash.to_nix_hash_string())); - } else { - // This is similar to the FOD case, with an empty fixed_output_path. - fp.push_str(&format!( - "output:out:{}", - derivation_or_fod_hash.to_nix_hash_string(), - )); - } - } else { - // This is similar to the FOD case, with an empty fixed_output_path. - fp.push_str(&format!( - "output:out:{}", - derivation_or_fod_hash.to_nix_hash_string(), - )); + output_path_name + }; + + // In the case this is a fixed-output derivation AND the + // hash mode is recursive AND the hash algo is sha256, a + // custom fingerprint is used to calculate the output path. + // + // In all other cases, the fingerprint is derived from the + // derivation_or_fod_hash. + let custom_fp: Option<String> = + if num_outputs == 1 && output_name == "out" && output.hash_with_mode.is_some() { + match &output.hash_with_mode { + Some(NixHashWithMode::Recursive(NixHash { + digest, + algo: HashAlgo::Sha256, + })) => Some(format!( + "source:sha256:{}:{}:{}", + data_encoding::HEXLOWER.encode(digest), + store_path::STORE_DIR, + output_path_name + )), + _ => None, } - fp.push_str(&format!(":{}:{}", store_path::STORE_DIR, name)); - fp + } else { + None }; - let abs_store_path = utils::build_store_path(false, &fp, name)?.to_absolute_path(); - - self.outputs.insert( - "out".to_string(), - Output { - path: abs_store_path.clone(), - hash_with_mode: Some(fixed_output_hash.clone()), - }, - ); - self.environment.insert("out".to_string(), abs_store_path); - } - }; + // If no custom_fp has been determined, use the default one. + let fp = custom_fp.unwrap_or(format!( + "output:{}:{}:{}:{}", + output_name, + derivation_or_fod_hash.to_nix_hash_string(), + store_path::STORE_DIR, + output_path_name, + )); + let abs_store_path = + utils::build_store_path(false, &fp, &output_path_name)?.to_absolute_path(); + + output.path = abs_store_path.clone(); + self.environment + .insert(output_name.to_string(), abs_store_path); + } Ok(()) } |