feat: add compute_stream_hash method as lower-level way of hashing objects.

Author: Byron

gix-object/Cargo.toml

@@ -28,7 +28,7 @@ serde = ["dep:serde", "bstr/serde", "smallvec/serde", "gix-hash/serde", "gix-act
 verbose-object-parsing-errors = []
 
 [dependencies]
-gix-features = { version = "^0.35.0", path = "../gix-features", features = ["rustsha1"] }
+gix-features = { version = "^0.35.0", path = "../gix-features", features = ["rustsha1", "progress"] }
 gix-hash = { version = "^0.13.0", path = "../gix-hash" }
 gix-validate = { version = "^0.8.0", path = "../gix-validate" }
 gix-actor = { version = "^0.27.0", path = "../gix-actor" }

gix-object/src/lib.rs

@@ -364,7 +364,8 @@ pub mod decode {
     }
 }
 
-/// A standalone function to compute a hash of kind `hash_kind` for an object of `object_kind` and its `data`.
+/// A function to compute a hash of kind `hash_kind` for an object of `object_kind` and its `data`.
+#[doc(alias = "hash_object", alias = "git2")]
 pub fn compute_hash(hash_kind: gix_hash::Kind, object_kind: Kind, data: &[u8]) -> gix_hash::ObjectId {
     let header = encode::loose_header(object_kind, data.len() as u64);
 
@@ -374,3 +375,23 @@ pub fn compute_hash(hash_kind: gix_hash::Kind, object_kind: Kind, data: &[u8]) -
 
     hasher.digest().into()
 }
+
+/// A function to compute a hash of kind `hash_kind` for an object of `object_kind` and its data read from `stream`
+/// which has to yield exactly `stream_len` bytes.
+/// Use `progress` to learn about progress in bytes processed and `should_interrupt` to be able to abort the operation
+/// if set to `true`.
+#[doc(alias = "hash_file", alias = "git2")]
+pub fn compute_stream_hash(
+    hash_kind: gix_hash::Kind,
+    object_kind: Kind,
+    stream: &mut dyn std::io::Read,
+    stream_len: u64,
+    progress: &mut dyn gix_features::progress::Progress,
+    should_interrupt: &std::sync::atomic::AtomicBool,
+) -> std::io::Result<gix_hash::ObjectId> {
+    let header = encode::loose_header(object_kind, stream_len);
+    let mut hasher = gix_features::hash::hasher(hash_kind);
+
+    hasher.update(&header);
+    gix_features::hash::bytes_with_hasher(stream, stream_len, hasher, progress, should_interrupt)
+}

gix-object/tests/object.rs

@@ -1,4 +1,5 @@
 use std::path::PathBuf;
+use std::sync::atomic::AtomicBool;
 
 use gix_hash::ObjectId;
 
@@ -21,6 +22,35 @@ fn compute_hash() {
     );
 }
 
+#[test]
+fn compute_stream_hash() {
+    let hk = gix_hash::Kind::Sha1;
+    assert_eq!(
+        gix_object::compute_stream_hash(
+            hk,
+            gix_object::Kind::Blob,
+            &mut &[][..],
+            0,
+            &mut gix_features::progress::Discard,
+            &AtomicBool::default()
+        )
+        .expect("in-memory works"),
+        gix_hash::ObjectId::empty_blob(hk)
+    );
+    assert_eq!(
+        gix_object::compute_stream_hash(
+            hk,
+            gix_object::Kind::Tree,
+            &mut &[][..],
+            0,
+            &mut gix_features::progress::Discard,
+            &AtomicBool::default()
+        )
+        .expect("in-memory works"),
+        gix_hash::ObjectId::empty_tree(hk)
+    );
+}
+
 use gix_testtools::Result;
 
 #[cfg(not(windows))]