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author | Florian Klink <flokli@flokli.de> | 2023-02-01T10·32+0100 |
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committer | clbot <clbot@tvl.fyi> | 2023-02-01T13·43+0000 |
commit | 366d2c5e92dd36c3bb81397c8031c6e0227de3ce (patch) | |
tree | 41da409d9013dcbd3c09fc36aedc14eda63ecd30 /tvix/nix-compat/src/derivation/utils.rs | |
parent | 2551adb4f1b127fd5bef4c2bb96fd361e4fcc0df (diff) |
refactor(tvix/nix-compat/derivation): remove module inception r/5805
The module `src/derivation/derivation.rs` is a sign of module inception. Move the Derivation struct definiton up into `src/derivation/mod.rs`, and some of the helpers in a `util.rs`. Change-Id: Ib24a5f8a27bdd45df8b1fa2b3482a79b33cab8d5 Reviewed-on: https://cl.tvl.fyi/c/depot/+/7997 Reviewed-by: tazjin <tazjin@tvl.su> Tested-by: BuildkiteCI Autosubmit: flokli <flokli@flokli.de>
Diffstat (limited to '')
-rw-r--r-- | tvix/nix-compat/src/derivation/utils.rs | 78 |
1 files changed, 78 insertions, 0 deletions
diff --git a/tvix/nix-compat/src/derivation/utils.rs b/tvix/nix-compat/src/derivation/utils.rs new file mode 100644 index 000000000000..77ac94b42462 --- /dev/null +++ b/tvix/nix-compat/src/derivation/utils.rs @@ -0,0 +1,78 @@ +use crate::derivation::DerivationError; +use crate::nixbase32; +use crate::store_path::{self, StorePath}; +use sha2::{Digest, Sha256}; + +/// compress_hash takes an arbitrarily long sequence of bytes (usually +/// a hash digest), and returns a sequence of bytes of length +/// output_size. +/// +/// It's calculated by rotating through the bytes in the output buffer +/// (zero- initialized), and XOR'ing with each byte of the passed +/// input. It consumes 1 byte at a time, and XOR's it with the current +/// value in the output buffer. +/// +/// This mimics equivalent functionality in C++ Nix. +fn compress_hash(input: &[u8], output_size: usize) -> Vec<u8> { + let mut output: Vec<u8> = vec![0; output_size]; + + for (ii, ch) in input.iter().enumerate() { + output[ii % output_size] ^= ch; + } + + output +} + +/// This returns a store path, either of a derivation or a regular output. +/// The string is hashed with sha256, its digest is compressed to 20 bytes, and +/// nixbase32-encoded (32 characters) +pub(super) fn build_store_path( + is_derivation: bool, + fingerprint: &str, + name: &str, +) -> Result<StorePath, DerivationError> { + let digest = { + let mut hasher = Sha256::new(); + hasher.update(fingerprint); + hasher.finalize() + }; + let compressed = compress_hash(&digest, 20); + if is_derivation { + StorePath::from_string(format!("{}-{}.drv", nixbase32::encode(&compressed), name).as_str()) + } else { + StorePath::from_string(format!("{}-{}", nixbase32::encode(&compressed), name,).as_str()) + } + .map_err(|_e| DerivationError::InvalidOutputName(name.to_string())) + // Constructing the StorePath can only fail if the passed output name was + // invalid, so map errors to a [DerivationError::InvalidOutputName]. +} + +/// Build a store path for a literal text file in the store that may +/// contain references. +pub fn path_with_references<S: AsRef<str>, I: IntoIterator<Item = S>, C: AsRef<[u8]>>( + name: &str, + content: C, + references: I, +) -> Result<StorePath, DerivationError> { + let mut s = String::from("text"); + + for reference in references { + s.push(':'); + s.push_str(reference.as_ref()); + } + + let content_digest = { + let mut hasher = Sha256::new(); + hasher.update(content); + hasher.finalize() + }; + + s.push_str(&format!( + ":sha256:{:x}:{}:{}", + content_digest, + store_path::STORE_DIR, + name + )); + + build_store_path(false, &s, name) +} |