Allow find object by prefix

Author: Brooooooklyn

Diff for: libgit2-sys/lib.rs

@@ -2205,6 +2205,13 @@ extern "C" {
         id: *const git_oid,
         kind: git_object_t,
     ) -> c_int;
+    pub fn git_object_lookup_prefix(
+        dest: *mut *mut git_object,
+        repo: *mut git_repository,
+        id: *const git_oid,
+        len: size_t,
+        kind: git_object_t,
+    ) -> c_int;
     pub fn git_object_type(obj: *const git_object) -> git_object_t;
     pub fn git_object_peel(
         peeled: *mut *mut git_object,

Diff for: src/repo.rs

@@ -1459,6 +1459,25 @@ impl Repository {
         }
     }
 
+    /// Lookup a reference to one of the objects by id prefix in a repository.
+    pub fn find_object_by_prefix(
+        &self,
+        prefix_hash: &str,
+        kind: Option<ObjectType>,
+    ) -> Result<Object<'_>, Error> {
+        let mut raw = ptr::null_mut();
+        unsafe {
+            try_call!(raw::git_object_lookup_prefix(
+                &mut raw,
+                self.raw(),
+                Oid::from_str(prefix_hash)?.raw(),
+                prefix_hash.len(),
+                kind
+            ));
+            Ok(Binding::from_raw(raw))
+        }
+    }
+
     /// Create a new direct reference.
     ///
     /// This function will return an error if a reference already exists with
@@ -3678,6 +3697,17 @@ mod tests {
         assert_eq!(repo.head().unwrap().target().unwrap(), main_oid);
     }
 
+    #[test]
+    fn smoke_find_object_by_prefix() {
+        let (_td, repo) = crate::test::repo_init();
+        let head = repo.head().unwrap().target().unwrap();
+        let head = repo.find_commit(head).unwrap();
+        let head_id = head.id();
+        let head_prefix = &head_id.to_string()[..7];
+        let obj = repo.find_object_by_prefix(head_prefix, None).unwrap();
+        assert_eq!(obj.id(), head_id);
+    }
+
     /// create the following:
     ///    /---o4
     ///   /---o3