feat(tvix/eval): implement `builtins.hashFile` r/7625

The primary addition is the `builtin_hashFile` function which attempts
value-path coercion and on success reads the file to a nix_string.
Similar to the `builtins_hashString` implementation, the hash is then
derived using the `hash_nix_string` function in the introduced hash
module which has extracted hashing functionality initially specified in
cl/11005.

Change-Id: I5e3ef0317223af99488ebb79efc2fb49b4cbc1b6
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11007
Tested-by: BuildkiteCI
Reviewed-by: flokli <flokli@flokli.de>

1 files changed, 3 insertions, 22 deletions

diff --git a/tvix/eval/src/builtins/mod.rs b/tvix/eval/src/builtins/mod.rs
index 119c0bda2dc3..0e0890f7cd28 100644
--- a/tvix/eval/src/builtins/mod.rs
+++ b/tvix/eval/src/builtins/mod.rs
@@ -5,14 +5,9 @@
 
 use bstr::{ByteSlice, ByteVec};
 use builtin_macros::builtins;
-use data_encoding::HEXLOWER;
 use genawaiter::rc::Gen;
 use imbl::OrdMap;
-use md5::Md5;
 use regex::Regex;
-use sha1::Sha1;
-use sha2::digest::Output;
-use sha2::{Digest, Sha256, Sha512};
 use std::cmp::{self, Ordering};
 use std::collections::VecDeque;
 use std::collections::{BTreeMap, HashSet};
@@ -24,12 +19,14 @@ use crate::vm::generators::{self, GenCo};
 use crate::warnings::WarningKind;
 use crate::{
     self as tvix_eval,
+    builtins::hash::hash_nix_string,
     errors::{CatchableErrorKind, ErrorKind},
     value::{CoercionKind, NixAttrs, NixList, NixString, Thunk, Value},
 };
 
 use self::versions::{VersionPart, VersionPartsIter};
 
+mod hash;
 mod to_xml;
 mod versions;
 
@@ -692,23 +689,7 @@ mod pure_builtins {
     #[builtin("hashString")]
     #[allow(non_snake_case)]
     async fn builtin_hashString(co: GenCo, algo: Value, s: Value) -> Result<Value, ErrorKind> {
-        fn hash<D: Digest>(b: &[u8]) -> Output<D> {
-            let mut hasher = D::new();
-            hasher.update(b);
-            hasher.finalize()
-        }
-
-        let s = s.to_str()?;
-
-        let encoded_hash = match algo.to_str()?.as_bytes() {
-            b"md5" => HEXLOWER.encode(hash::<Md5>(&s).as_bstr()),
-            b"sha1" => HEXLOWER.encode(hash::<Sha1>(&s).as_bstr()),
-            b"sha256" => HEXLOWER.encode(hash::<Sha256>(&s).as_bstr()),
-            b"sha512" => HEXLOWER.encode(hash::<Sha512>(&s).as_bstr()),
-            _ => return Err(ErrorKind::UnknownHashType(s.into())),
-        };
-
-        Ok(Value::from(encoded_hash))
+        hash_nix_string(algo.to_str()?, s.to_str()?).map(Value::from)
     }
 
     #[builtin("head")]